CANADA- BRITISH COLUMBIA OKANAGAN BASIN ......2.1 Basic Data on Okanagan Valley Drainage Basin 7 3.1...
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CANADA- BRITISH COLUMBIA OKANAGAN BASIN AGREEMENT
Transcript of CANADA- BRITISH COLUMBIA OKANAGAN BASIN ......2.1 Basic Data on Okanagan Valley Drainage Basin 7 3.1...
CANADA- BRITISH COLUMBIA
OKANAGAN BASIN AGREEMENT
FINAL PUBLICATIONS IN THIS SERIES
1. SUMMARY REPORT OF THE CONSULTATIVE BOARD
2. THE MAIN REPORT OF THE CONSULTATIVE BOARD
3. TECHNICAL SUPPLEMENTS TO THE MAIN REPORT
I Water Quantity in the Okanagan Basin
II Water Quantity Computer Models
III Water Quantity Alternatives and Supporting Water Quantity Data
IV Water Quality and Waste Loadings in the Okanagan Basin
V The Limnology of the Major Okanagan Basin Lakes
VI Review and Evaluation of Wastewater Treatment in the Okanagan Basin
VII Value and Demand for Water in the Okanagan Basin
VIII Water-Based Recreation in the Okanagan Basin
IX Fisheries and Wildlife in the Okanagan Basin
X Economic Growth Projections
XI Public Involvement
XII Planning, Administration and Institutional Considerations
Cover Photos by Tom W. Hall –
Enquiries for copies of these publications should be directed to --
B.C. Water Resources Service,
Parliament Buildings,
VICTORIA, B.C.
CANADA-BRITISH COLUMBIA OKANAGAN BASIN AGREEMENT
TECHNICAL SUPPLEMENT V
TO THE
FINAL REPORT
THE LIMNOLOGY
OF THE
MAJOR OKANAGAN BASIN LAKES
PUBLISHED BY
OFFICE OF THE STUDY DIRECTOR
BOX 458, PENTICTON, B.C.
APRIL, 1974
THE CONSULTATIVE BOARD WISH TO ACKNOWLEDGE
THE CONTRIBUTION OF THE FOLLOWING PEOPLE IN
THE PREPARATION OF THIS TECHNICAL SUPPLEMENT
COMPILATION
MORLEY E. PINSENT B.C. FISH & WILDLIFE BRANCH
DEPARTMENT OF RECREATION & CONSERVATION VICTORIA, B.C.
JOHN G. STOCKNER PACIFIC ENVIRONMENT INSTITUTE
DEPARTMENT OF THE ENVIRONMENT, CANADA NORTH VANCOUVER, B.C.
CONTRIBUTING AUTHORS
T.G. NORTHCOTE, GORDON HALSEY AND S. MACDONALD
(MAINSTEM FISHERIES)
B.C. FISH AND WILDLIFE BRANCH, VICTORIA, B.C.
B. ST. JOHN (LIMNOGEOLOGICAL STUDIES)
C.C.I.W., I.W.D., ENVIRONMENT CANADA
J. BLANTON AND H.Y.F. NG, (PHYSICAL LIMNOLOGY)
C.C.I.W., I.W.D., ENVIRONMENT CANADA
D. WILLIAMS AND A. LERMAN, (CHEMICAL LIMNOLOGY)
C.C.I.W., I.W.D., ENVIRONMENT CANADA
K. PATALAS, O. SAETHER, J.G. STOCKNER,
MARGARET P. MCLEAN, AND A. SALKI,
(BIOLOGICAL STUDIES)
F.R.B, I.W.D., ENVIRONMENT CANADA
TYPIST
L.W. JACKSON, STUDY OFFICE
EDITORIAL REVIEW
JOHN G. STOCKNER PACIFIC ENVIRONMENT INSTITUTE
R.J. BUCHANAN B.C. WATER INVESTIGATIONS BRANCH
A. MURRAY THOMSON STUDY DIRECTOR
THE OKANAGAN BASIN IN
BRITISH COLUMBIA - CANADA Figure A
FOREWORD
This Technical Supplement describes and presents the results
of limnological research on the main valley lakes as carried out
under the Canada-British Columbia Okanagan Basin Agreement. The
results of associated studies on water quality, and waste
treatment for the control of nutrient discharges, are covered in
Technical Supplements IV and VI respectively. The presentation
and discussion of alternatives concerning limnology is confined
to the main report.
The material presented in this supplement supercedes that of
all earlier preliminary reports or publications prepared under
the terms of reference of the Agreement.
A. Murray Thomson
Study Director
TABLE OF CONTENTS
FOREWORD iii
TABLE OF CONTENTS v
LIST OF TABLES viii
LIST OF FIGURES x
GLOSSARY OF TERMS xii
CONTENTS
CHAPTER 1 INTRODUCTION 1
1 .1 Rationale 1
1 .2 Approach 1
1 .3 Scope 3
CHAPTER 2 STUDY AREA DESCRIPTION 5
CHAPTER 3 METHODS AND APPROACH 9
3.1 Geological Studies 9
3.2 Physical Studies 11
3.3 Chemical Studies 14
3.4 Biological Studies 15
3.4.1 Nutrient Bioassay 15
3.4.2 Periphyton and Rooted Aquatic Vegetation 22
3.4.3 Bottom Fauna 25
3.4.4 Zooplankton 26
3.4.5 Fishes 26
CHAPTER 4 GEOLOGY OF THE MAIN VALLEY LAKES 31
4.1 Previous Work 31
4.2 Results 31
CHAPTER 5 PHYSICAL CHARACTERISTICS OF THE MAIN VALLEY LAKES 45
5.1 Previous Work 45
5.2 Results 45
CHAPTER 6 CHEMICAL CHARACTERISTICS OF THE MAIN VALLEY LAKES 55
6.1 Previous Work 55
6.2 Results 55
6.2.1 Dissolved Oxygen 55
6.2.2 Nutrients 58
6.2.3 Major Ions 60
PAGE
CHAPTER 7 BIOLOGICAL CHARACTERISTICS OF THE MAIN VALLEY LAKES 63
7.1 Nutrient Bioassay 63 7.1.1 Nutrient Enrichment Bioassay 63 7.1.2 Pure Culture Bioassay 67 7.1.3 Sewage Enrichment Experiments 72 7.1.4 Trace Metal Experiments 81 7.1.5 General Discussion 89
7.2 Phytoplankton 91 7.3 Attached Algae and Rooted Aquatic Vegetation 93 7.4 Bottom Fauna 98 7.4.1 Okanagan Lake 98 7.4.2 Skaha Lake 101 7.4.3 Osoyoos Lake 102 7.4.4 Kalamalka Lake 102 7.4.5 Wood Lake 103
7.5 Zooplankton 103 7.5.1 Okanagan Lake 104 7.5.2 Skaha Lake 107 7.5.3 Osoyoos Lake 107 7.5.4 Kalamalka Lake 107 7.5.5 Wood Lake 108 7.5.6 General Discussion 108
7.6 Fishes 109 7.6.1 Within-Lake Comparisons of Relative Abundance 111 7.6.2 Comparisons of Selected Fish Population Parameters 111
Amongst Lakes 7.6.3 Summary 118
CHAPTER 8 NUTRIENT LOADING AND THE TROPHIC STATE OF THE MAIN 121
VALLEY LAKES
8.1 General 121
8.2 Nutrient Sources 125
8.2.1 Osoyoos Lake 125 8.2.2 Vaseux Lake 125 8.2.3 Skaha Lake 125 8.2.4 Okanagan Lake 125 8.2.5 Kalamalka Lake 125 8.2.6 Wood Lake 127
CHAPTER 9 ESTABLISHMENT OF LOADING CRITERIA FOR THE OKANAGAN 129 MAIN VALLEY LAKES
9.1 Standards and Benefits for the Control of Algal and 129
Other Aquatic Plant Growth in the Main Valley Lakes 9.2 Role of Nutrients in Biological Production 129 9.3 Phosphorus forms and Budgets 130 9.4 Criteria for Phosphorus Loadings 131 9.4.1 Okanagan Lake 132 9.4.2 Skaha Lake 135 9.4.3 Osoyoos Lake 135 9.4.4 Kalamalka Lake 135 9.4.5 Wood Lake 136 9.4.6 Vaseux Lake 136
9.5 Costs and Benefits Associated with Lake Water Quality 136
PAGE
CHAPTER 10 DISCUSSION 137
10.1 Osoyoos Lake 137
10.2 Vaseux Lake 137
10.3 Skaha Lake 140
10.4 Okanagan Lake 142
10.5 Wood Lake 142
10.6 Kalamalka Lake 145
10.7 General Discussion 147
ACKNOWLEDGEMENTS 149
REFERENCES 151
APPENDICES 159
APPENDIX A MAJOR LIMNOLOGICAL STUDIES AND RESPONSIBLE 161
PERSONNEL AND AGENCIES
APPENDIX B GEOLIMNOLOGY RESULTS 163
APPENDIX C CHEMICAL LIMNOLOGY DATA FOR THE OKANAGAN MAIN 183
VALLEY LAKES
APPENDIX D PHYSICAL LIMNOLOGY DATA 197
APPENDIX E BIOASSAY PROGRAM 221
APPENDIX F CRUSTACEAN PLANKTON AND ASSOCIATED DATA 227
APPENDIX G BENTHIC (BOTTOM) FAUNA DATA 241
APPENDIX H PERIPHYTON 257
261
MAP SECTION
Map 1 Plan and Profile of Okanagan Main Valley Lakes
Map 2 The Distribution of Sampling Stations and the Horizontal
Distribution of Net Plankton Settled Volumes in Okanagan,
Skaha and Osoyoos Lakes on September 9-11, 1969 and August
24-27, 1971; and in Kalamalka and Wood Lakes on August 25,
1971
Map 3 Some Limnological Characteristics of Osoyoos Lake
Map 4 Some Limnological Characteristics of Vaseux Lake
Map 5 Some Limnological Characteristics of Skaha Lake
Map 6 Some Limnological Characteristics of the Southern Section of
Okanagan Lake
Map 7 Some Limnological Characteristics of the Central Section of
Okanagan Lake
Map 8 Some Limnological Characteristics of the Northern Section of
Okanagan Lake
Map 9 Some Limnological Characteristics of Kalamalka Lake
Map 10 Some Limnological Characteristics of Wood Lake
LIST OF TABLES TABLE NUMBER TITLE PAGE
2.1 Basic Data on Okanagan Valley Drainage Basin 7
3.1 Sampling Dates, Okanagan Basin Lakes Chemistry Program 16
3.2 Concentrations of NO3(N) and PO4(P) and CO2 Used in Nutrient 18
Enrichment Bioassay
3.3 Concentrations of PO4(P) and NO3(N) Used in Sewage Enrich- 21
ment Experiments.
3.4 Trace Metal, Chelator and Nutrient Additions, 1971 23
4.1 Minimum Thickness of Unconsolidated Material under the 33
Centers of the Main Valley Okanagan Lakes
4.2 Sediment-Size Distribution in Main Valley Okanagan Lakes 33
4.3 Depth to Man's Influence and Net Accumulation Rate of 34
Sediment in Each of the Okanagan Main Valley Lakes
4.4 Mean Concentrations of Major Elements in Surface Sediment 37
Samples from Okanagan Main Valley Lakes
4.5 Mean Carbon Content of Surface Sediments and Mean Carbon 39
Accumulation Rates for Okanagan Main Valley Lakes
4.6 Acid Extractable Inorganic Phosphorus in Sediments from 41
the Okanagan Main Valley Lakes
5.1 Morphometry of the Six Main Valley Lakes in the Okanagan Basin 46
5.2 Mean Annual Outflow and Theoretical Water Replacement Time, 46
(Residence Time), Okanagan Main Valley Lakes
5.3 Period of Maximum Surface Temperatures for Each Lake where 49
Moored Thermographs were Located
5.4 Summer Heat Incomes for the Main Valley Lakes in 1971 49
5.5 Transmission Meter Values for the Five Main Valley Lakes 51
5.6 General Details of the Skaha Lake Diffusion Experiments 51
6.1 Concentrations of Dissolved Oxygen in the Okanagan Main 56
Valley Lakes, Expressed in Parts Per Million
6.2 Daily Oxygen Depletion Rates, Areal Depletion Rates and 57
Trophic Indices for the Okanagan Main Valley Lakes
6.3 Average Concentrations of Nitrogen, Phosphorus and 57
Chlorophyll-a in the Okanagan Main Valley Lakes
6.4 Average Seasonal Concentration and Lake Average of Major 61
Anions/Cations in Okanagan Main Valley Lakes
7.1 Results of Trace Metal Experiments 1971 - Osoyoos Lake 85
7.2 Results of Trace Metal Experiments 1971 - Skaha Lake 85
7.3 Results of Trace Metal Experiments 1971 - Okanagan Lake 88
7.4 Results of Trace Metal Experiments 1971 - Wood Lake 88
7.5 Phytoplankton by Seasons 92
7.6 Lake Area, Littoral Area, and Percent of Lake Area Comprised 94
of Littoral
TABLE NUMBER TITLE PAGE
7.7 Tentative Identification of Aquatic Macrophytes in the 96
Okanagan Main Valley Lakes
7.8 Average Net Production Rate of Periphyton from April 19 to 97
September 17 (152 Days) on Glass Slides in the Okanagan Lakes
7.9 Seasonal Succession of Dominant Algae in the Periphyton of 99
the Okanagan Main Valley Lakes
7.10 The Average Number of Fauna per Square Meter in the Okanagan 100
Main Valley Lakes, from all Depths Sampled
7.11 List of Species Found in Net Plankton of Lakes Okanagan, and 105
Kalamalka in the Period from 1935 to 1971.
7.12 Number per cm2 and Percent of Total Composition of Zooplankton 106
Species in Five Okanagan Main Valley Lakes
7.13 Average Numbers of Zooplankton Crustaceans in the Great 109
and Okanagan Basin Lakes
7.14 Species of Fish from Okanagan Basin Lakes at Designated 110
Stations during the 1971 Survey
7.15 Number of Fish Taken in Combined Spring, Summer and Autumn 112
(Standard) Net Sets at Designated Stations in Kalamalka,
Okanagan and Skaha Lakes
7.16 Number of Fish Taken in Standard Summer Net Sets near Desig- 116
nated Stations in Skaha Lake, 1948 and 1971.
7.17 Number of Fish Taken in Standard Summer Net Sets near Desig- 116
nated Stations in Wood and Okanagan Lakes, 1935 and 1971.
8.1 Major Nutrient Loading to the Main Valley Lakes 122
8.2 Values of the Total Phosphorus Loadings to the Okanagan 124
Lakes and Other Parameters of Importance in the
Calculation of the Total Load
9.1 Forms of Phosphorus Present in Surface and Wastewaters 131
9.2 Total Phosphorus Concentrations and Loading Criteria - Main 134
Valley Lakes
10.1 Summary of Limnological Data – Osoyoos Lake 138
10.2 Summary of Limnological Data – Vaseux Lake 139
10.3 Summary of Limnological Data – Skaha Lake 141
10.4 Summary of Limnological Data – Okanagan Lake 143
10.5 Summary of Limnological Data – Wood Lake 144
10.6 Summary of Limnological Data – Kalamalka Lake 146
LIST OF FIGURES
FIGURE NUMBER TITLE PAGE
1.1 Schematic Representation of Human Factors Affecting 2 (Inputs) and Affected by (Outputs) the Trophic State
of the Okanagan Main Valley Lakes
2.1 Key Map of the Okanagan Drainage Basin 6
3.1 Okanagan Basin Showing Bottom Sample Stations and Core 10 Locations
3.2 Map of Skaha Lake Showing Short Core Sampling Locations 12
3.3 Apparatus Used to Collect Periphyton in the Okanagan 24 Main Valley Lakes
3.4 Net Setting Locations-Gill Nets and Depth Profiles for 28 the Standard Netting Stations - Okanagan Main Valley Lakes
4.1 Abundance of Diatoms in Lake Sediments as a Function of 35 Depth for Wood, Kalamalka, Okanagan and Osoyoos Lakes
4.2 Profiles of Carbon Content of Cores from the Okanagan 40 Main Valley Lakes
4.3 Profile of Mercury Content of Sediments in the Okanagan 43 Lakes System Along the Deepest Part of Each Lake.
5.1 Volumes Associated with Given Temperature Ranges Observed 47 During the 1971 Monitor Cruises in Osoyoos, Skaha and Okanagan Lakes
5.2 Volumes Associated with Given Temperature Ranges Observed 48 During the 1971 Monitor Cruises in Wood and Kalamalka
Lakes.
5.3 Synoptic Maps of Dye Distribution for Skaha Lake, 52 3-6 April, 1971
5.4 Schematic Zones of Influence by the Okanagan River as it 53 Enters Skaha Lake
7.1 Results of the Nutrient Enrichment Bioassay Experiments, 64 Okanagan Main Valley Lakes, 1971.
7.2 Results of Pure Culture Bioassay Experiments from Three 68 Osoyoos Lake Stations (1971).
7.3 Results of Pure Culture Bioassay Experiments from One 70 Vaseux Lake Station (1971).
7.4 Results of Pure Culture Bioassay Experiments from Four 71 Skaha Lake Stations (1971).
7.5 Results of Pure Culture Bioassay Experiments from Four 73 North Okanagan Lake Stations (1971).
7.6 Results of Pure Culture Bioassay Experiments from Six 74 South Okanagan Lake Stations (1971).
7.7 Results of Pure Culture Bioassay Experiments from Five 75 Kalamalka Lake Stations (1971).
7.8 Results of Pure Culture Bioassay Experiments from Three 76 Wood Lake Stations (1971).
FIGURE NUMBER TITLE PAGE
7.9 Bioassay Results, Sewage Enrichment Experiments after 78 Nine Days' Growth on Osoyoos Lake Water, 1971
7.10 Bioassay Results, Sewage Enrichment Experiments after 79 Nine Days' Growth on Skaha Lake Water, 1971
7.11 Bioassay Results, Sewage Enrichment Experiments after 80 Nine Days' Growth on Okanagan Lake Mater, 1971.
7.12 Bioassay Results, Sewage Enrichment Experiments after 82 Nine Days' Growth on Kalamalka Lake Mater, 1971
7.13 Bioassay Results, Sewage Enrichment Experiments after 83 Nine Days' Growth on Mood Lake Mater, 1971
7.14 Total Catch of Fish in Standard Gill Net Sets at Desig- 114 nated Stations of the Okanagan Main Valley Lakes
7.15 Number of Fish Caught in Standard Net Sets at Designated 115 Stations of the Okanagan Main Valley Lakes
7.16 Typical Weight-Length Regressions for Selected Species 119 of Fish from the Okanagan Main Valley Lakes
8.1 Relation Between Chlorophyll Concentration and Total 123 Phosphorus Content of Water from the Okanagan Main Valley Lakes
8.2 The Annual Total Phosphorus Load to the Main Valley Lakes 126 of the Okanagan Basin, 1969 - 1971
9.1 Schematic Drawing of Relationship Between Nutrient Load- 133 ings and Biological Production, and Range for Selecting Loading Criteria for Main Valley Lakes
GLOSSARY OF TERMS
Algae Chlorophyll-bearing plants – some are planktonic and others are filamentous and attached
Aquatic Living in Water
Benthos Plants or animals living on the lake bottom
B.P. Before Present time
Chironomids Aquatic benthic insects (midges)
Epilimnion Upper region of warm circulating lake water during summer period
Eutrophic Nutrient-rich lake, high biological production
Fauna Animals Flora Plants
Hypolimnion Deep, cold and relatively undisturbed region of lake in summer period
Lake overturn Period of complete mixing, in most lakes occurring in winter and spring
Limnology The study of bodies of fresh water in all their aspects
Littoral zone The submerged shoreline of lakes supporting plant growth
Lock-in nutrients Nutrient elements which have formed a bond with bottom sediments and which prevents their recycling (occurs only in well-oxygenated lakes).
Macrophytes Aquatic rooted vegetation
Mesotrophic Moderate nutrient concentration and production
Metalimnion (Thermocline) Water layer of rapidly decreasing temperature between the epilimnion and the hypolimnion
NO3 (N) Nitrate Nitrogen
Nutrient elements Elements essential for the growth and reproduction of plant and other simple forms of aquatic life. The most critical nutrient elements (those most often in short supply) are nitrogen and phosphorus
Oligochaetes Benthic Segmented worms
Oligotrophic Nutrient-poor lake, low biological production
Periphyton Attached aquatic algae
Photic zone Limit of light penetration, zone of biological production
Phytobenthic Communities Plant populations at bottom of lakes
Plankton Microscopic floating or drifting plant and animal life of the sea or lakes
PO4 (P) Phosphate Phosphorus
Salmonids Any fish of the Trout-Salmon family
Secchi Depth Lake transparency as measured by extinction of a 22 cm. (8”) white disc.
Zoobenthic Communities Animal populations at bottom of lakes
CHAPTER 1
Introduction
1.1 RATIONALE
It would seem fitting, and necessary that Limnology: "the study of
physical, chemical, meteorological and biological conditions in fresh
waters" (Grove, 1973), should play a role in the Okanagan Basin Study.
Limnology is an essential part of most water body examinations in that
it is the tool needed to determine the present trophic state of waters, a
basis for future planning and management.
Many attributes and functions, of life in the Okanagan Basin affect and
are affected by the trophic state of the basin lakes (Figure 1.1).
Limnological study then, is in this case a descriptive exercise to provide
a firm data base for water planning and management in the Okanagan main
valley lakes. It provides a historical perspective of the lakes as well as
an analysis of the dynamic state of the lakes.
The general objective of the limnology program was to provide a broad
characterization of the main valley lakes with a view to determining the
cause of apparent water quality deteriorations. Based on the knowledge
gained from this study, standards were also established with respect to the
annual phosphorus load each of the main valley lakes can assimilate.
1.2 APPROACH
As with the entire study, the limnology program was carried out
through a series of defined tasks. Major limnology tasks, agency and
personnel responsibilities are outlined in Appendix A, Data summaries for
each of the major fields of study are detailed in Appendices B to H.
This technical supplement is an attempt to integrate the separate
tasks and manuscript reports pertaining to limnology into an overview of
the trophic state of each lake and situations pertaining thereto. Due to
the organization of tasks and specialities of sundry investigators, it has
been necessary to first organize the supplement in a way which presents
specific aspects (i.e. geology, chemistry, etc.) of all lakes and then
integrate these in the final chapters.
1.3 SCOPE
The limnology program adopted a wide scope in an attempt to get as
complete an impression as possible of the limnological state, trophic
condition and factors affecting the main valley lakes.
Geological studies centered on basin structure, sedimentation rates and
paleolimnological survey. These studies present the history of the main
valley lakes on a geologic time scale as well as giving valuable
indications of more recent man influenced changes in the lakes.
Physical studies provided data on lake morphometry, temperature series,
heat content, light transmittance and water transparency. Character of the
Okanagan River plume as it enters Skaha Lake was also examined. Chemical
studies measured oxygen, nutrient and major ion concentrations in the lake
waters.
Biological studies involved nutrient bioassay; phytoplankton,
periphyton and aquatic macrophyte studies as well as zooplankton, bottom
fauna and fish studies. Biological studies actually represent an
examination of the end product of the physics, chemistry, geology and
meteorology of waters since the trophic state of a lake as expressed by
densities and varieties of biota, is dependent upon these non-living
aspects of a particular water. The expression of a particular trophic
state in a lake by its biota is usually the factor most affecting people's
use of that water. By understanding the flora and fauna of a lake and the
critical factors regulating its life processes, the key to controlling it
for man's benefit is provided.
The Okanagan main valley lakes have been subject to limnological study
prior to the inception of the Canada-British Columbia Okanagan Basin
Agreement. Specifically oriented studies are referred to in the
appropriate sections where a more detailed review can be accorded them. In
1935, Rawson conducted a general limnological survey of Okanagan, Wood,
Ellison and Kalamalka Lakes, which provided a basis for later studies.
This study was part of a more extensive survey conducted to determine the
condition of some of the lakes as a scientific basis for development of a
comprehensive fish culture program (Clemens, et al, 1939). Sismey (1921)
collected algae from a number of Okanagan Valley lakes as part of a
floristic survey of central interior B.C.
(h) greatest oxygen deficit of any basin lake
(I) lowest average transparency
Wood Lake in 1935 was at about the same trophic state as Skaha Lake is
today. Some of the largest kokanee found in the basin were caught in Wood
Lake in the 1940's, but today few are caught at all and most are small. The
paucity of benthos fauna may be related to the presence of a toxic
substance.
Wood Lake is being loaded with phosphorus at a rate at least equivalent
to the recommended maximum and probably in excess of it. Due to the poor
water quality of Wood Lake at present, a reduction of from 30 to 40% of
total annual phosphorus loading is recommended to at least maintain and,
hopefully, improve water quality.
10.6 KALAMALKA LAKE (Table 10.6)
Kalamalka Lake is the most oligotrophic lake in the basin and lies in
juxtaposition to Wood Lake. the most eutrophic. Many hypotheses have been
advanced to explain the persistent oligotrophic condition displayed by this
lake, the most credible being a co-precipitation mechanism involving PO4 and
CaCO3. Most nutrients enter Kalamalka Lake from Coldstream Creek. Present
evidence points to little change over conditions observed by Clemens and
Rawson in 1935:
(a) no oxygen deficit in hypolimnion (b) lowest PO4(P) concentrations at spring overturn and throughout the
summer (c) lowest average chlorophyll-a concentration (10 ug/liter) (d) lowest phytoplankton density (e) dominance of diatoms and phytoflagellates (f) lowest daily periphyton growth (g) low Zooplankton settled volume (h) low oligochaetes/chironomid ratio (i) small populations of coarse fish (j) highest salmonid relative abundance
The benthic fauna composition has shown changes since 1935 which can
be interpreted as a gradual response to an increased nutrient load over
the past 2 to 3 decades.
Kalamalka Lake is receiving phosphorus at below the recommended
maximum level. It is presently assimilating all incoming phosphorus and no
deterioration of water quality has occurred to date, except in localized
shoreline areas.
TABLE 10.6
SUMMARY OF LIMNOLOGICAL DATA - KALAMALKA LAKE
10.7 GENERAL DISCUSSION
From the above discussion some salient points emerge with regard to the
Okanagan Basin main valley lakes, their inter-relationships to each other and
of the use and misuse made of them by man. With these points identified, the
current trophic state of the lakes is established as well as some of the
mechanisms responsible for current water quality problems.
As mentioned previously, Okanagan Lake is the "master lake" in the system.
The ability of this lake to cushion effects from all its inflows and moderate
them with age is a crucial point in the water management of the basin. With
Okanagan Lake acting as a giant nutrient trap or repository, the effects of the
Okanagan River on downstream lakes will be less abrupt and decisive than would
be the case if Okanagan Lake were non-existant or much smaller.
Okanagan Lake, if loaded with nutrients heavily in excess of its capacity
to assimilate them, will build up an excess nutrient load with time. If this
should take place, then this enrichment would cause downstream as well as
within-lake problems for decades before a water renewal and sedimentation could
begin to ameliorate conditions. Thus, Okanagan Lake cannot be thought of as a
permanent repository for excess nutrients. The massive volume and long
exchange time of Okanagan Lake is a short-term boon, but a long term bane if it
is not properly understood and used by man.
Skaha Lake and Vaseux Lake are very directly affected by the water quality
of the Okanagan River. This effect is evident in Skaha Lake with the localized
problems that occur in the influence of the river plume. This is not a
reflection of present river water quality as it leaves Okanagan Lake, but is
instead due to the effluent from the Penticton Sewage Treatment Plant being
added to the river prior to its entry into Skaha Lake. Nonetheless it provides
an example of the dependence of Skaha Lake on good water quality from upstream.
Vaseux Lake, being in essence a widening and slowing of the Okanagan River,
merely reflects river water quality (Skaha Lake water) in a short term
lacustrine environment.
Osoyoos Lake is affected to a degree by the quality of the Okanagan
River, however river water quality is considerably modified by the time it
reaches the lake, thus the effects of Okanagan Lake are no longer of the same
magnitude.
The carbonate chemistry of Kalamalka Lake indicates it will maintain its
oligotrophic nature within the foreseeable future. Its ability to co-
precipitate phosphorus indicates that perhaps Kalamalka Lake provides something
of a small net downstream benefit, however it is suggested this may not be
highly significant.
From their beginning, lakes move independently toward eutrophy as part of
an aging process. This is an inherent happening which occurs irrespective of
outside
influence. It is also a momentum gathering process, in that the rate of
eutrophication increases with increasing degree of eutrophy. When the
activities of man are injected into such a system, generally the stage of
eutrophy is advanced unnaturally, thus the rate of eutrophication is
increased and a multiplier effect occurs. Wood Lake is an example of such
a case. Thirty years ago water quality was good and salmonid fishes large
and abundant. Due primarily to excessive nutrient additions from a number
of land sources, and a substantial increase in exchange time due to
headwater storage establishment, Wood Lake has become a problem area.
Excessive production of undesirable biota has made the lake essentially
unavailable to man for a number of potential uses. Fortunately, this
occurrence has had limited downstream effects, since Wood Lake flows into
the very oligotrophic Kalamalka Lake.
In summary, the Okanagan main valley lakes presently vary in trophic
state from the extremely oligotrophic Kalamalka Lake through Okanagan,
Skaha, Osoyoos, Vaseux to Wood Lake, the most eutrophic. All lakes are
being "hurried" toward eutrophy by the influence of man's activities.
Man's influence was first noted about 70 years ago, and is attributed to
agricultural activity. Urban and residential activities have been the
primary influences in the last two or three decades.
ACKNOWLEDGEMENTS
The authors in this case had the task of compiling into an overall
format, all the field studies pertaining to limnology which were part of
the Okanagan Basin Study. Thus, most of the original work and data is
that of other investigators. The major manuscript reports used in this
compilation are listed in a section of the References portion of the
supplement.
This supplement could not have been compiled without the
cooperation, support and hard work of all involved in the Okanagan Basin
study limnology program as well as the Study Office staff in Penticton.
The assistance of those listed below as well as many others too numerous
to mention, is here most gratefully acknowledged.
Freshwater Institute - Fisheries Research Board of Canada
Dr. K. Patalas Mr. A. Saiki Dr. 0. Saether Miss M. McLean Mr. G.D. Koshinsky* Mr. G. Girman Mr. R. Robarts Mr. P. Findlay Mr. B. Carney
Canada Centre for Inland Waters
Dr. J. Blanton Mr. H. Ng Dr. B. St. John Mr. D. Williams Dr. A. Lerman*
B.C. Fish and Wildlife Branch
Dr. T.G. Northcote*
Mr. T.G. Halsey Mr. S.J. MacDonald
Okanagan Basin Study Office
Mr. A. Murray Thomson Mr. G. McKenzie
*Affiliation shown is for the period 1969-72.
REFERENCES
REFERENCES A. MANUSCRIPT REPORTS
Manuscript reports prepared as part of the Canada-British Columbia
Okanagan Basin Agreement study which were used extensively in the
preparation of Technical Supplement V
Blanton, J.O. 1972, Relationships Between Heat Bontent and Thermal Structure in the Mainstem Lakes of the Okanagan Valley, British Columbia, 17pp
Blanton, J.O., and H.Y.F. Ng. 1971. Okanagan Basin Studies; Data Report on the Fall Survey, 1970. 125pp.
Blanton, J.O., and H.Y.F. Ng. 1972. The Physical Limnology of the Mainstem Lakes in the Okanagan Basin, 2 Volumes, 34pp, 24 figures, 2 appendices.
Blanton, J.O., and H.Y.F. Ng. 1972. The Circulation of the Effluent from the Okanagan River as it enters Skaha Lake. 23pp.
Lerman, A. 1972. Chemical Limnology of the Major Lakes in the Okanagan Basin:
Nutrient Budgets at Present and in the Future. 41pp.
Northcote, T.G., T.G. Halsey and S.J. MacDonald. 1972. Fish as Indicators of
Water Quality in the Okanagan Basin Lakes, British Columbia. 80pp.
Patalas, K and A. Saiki, 1973. Crustacean Plankton and the Eutrophication of Lakes in the Okanagan Valley, British Columbia. 34pp.
Saether, O.A., and M.P. McLean. 1972. A Survey of the Bottom Fauna in Wood,
Kalamalka and Skaha Lakes in the Okanagan Valley, British Columbia. 20pp
St. John, B.E. 1972. The Limnogeology of the Okanagan Mainstem Lakes, 46 pp.
Stockner, J.G. 1971. Preliminary Evaluation; Water Quality, 4pp.
1972. Diatom Succession in the Recent Sediments of Skaha Lake,
British Columbia. 17pp. 1972. Nutrient Loadings and Lake Management Alternatives. 13pp.
Stockner, N.J., G.R. Girman and R.D. Roberts. 1972. Algal Nutrient Addition and Pure Culture Bioassay Studies on Six Lakes in the Okanagan Basin, British Columbia. 52pp.
Stockner, J.G., M. Pomeroy, W. Carney and D.L. Findlay. 1972. Studies of Periphyton in Lakes of the Okanagan Valley, British Columbia. 19pp.
Stockner, J.G., W. Carney and G. McKenzie. 1972. Task 122: Phytobenthos, Littoral Mapping Supplement. 10pp. 16 plates
Williams, D.J. 1972. General Limnology of the Mainstem Lakes in the Okanagan Valley, British Columbia. 12pp.
REFERENCES
(Continued)
B. CITED LITERATURE
Alcock, F.R., and D.A. Clarke. MS 1968. Report to Pollution Control Board, South Okanagan Health Unit. 1-13.
American Public Health Association. 1965. Methods for the Examination of Water and Wastewater, 12th Ed., APHA, New York.
Anderson, T.W. 1972. Historical Evidence of Land Use in Pollen Stratigraphies from Okanagan Mainstem Lakes, B.C.; in preparation
Armstrong, F.A.J. and D.W. Schindler. 1971. Preliminary Chemical Characterization of Maters in the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. Canada 28: 171-187.
Armstrong, J.E., D.R. Crandell, D.J. Easterbrook, and J.B. Noble. 1965. Late Pleistocene Stratigraphy and Chronology in Southwestern British Columbia and Western Washington: Geol. Soc. Am. Bull., v.79; 321-330
Booth, D.M., T.J. Coulthard and J.R. Stein. 1969. Water Quality Deterioration in Osoyoos Lake, British Columbia: Paper presented at CSAE Annual Meeting, Saskatoon; August 24-28, 1969.
Burton, W. and J.F. Flannagan. In press. An improved Ekman-type garb.
Cairnes, C.E. 1932. Mineral Resources of Northern Okanagan Valley, British Columbia: Geol.Surv. Canada, Sum. Rept. 1931: Pt A, pp 66-109.
Cairnes, C.E. 1937. Kettle River Map Area, West Half, British Columbia: Geol. Surv. Canada; Paper 37-21.
Cairnes, C.E. 1939. The Shuswap Rocks of Southern British Columbia: Proc. Sixth Pacific Science Congress, Vol. I, pp. 259-272.
Clarke, D.A., South Okanagan Health Unit: Submarine Photometry Study, 1972.
Clemens, W.A., D.S. Rawson and J.L. McHugh. 1939. A biological survey of Okanagan Lake, British Columbia. Fish. Res. Bd., Canada; Bull. 56: 70p
Cleve-Euler, A. 1971. Die Deatomeen von Schewedn und Funnland. Almquist and Wiksells Boktrycheri, Stockholm, Sweden. 1171p
Coulthard, T.L., and J.R. Stein. 1969. Water Quality Deterioration in Osoyoos Lake, British Columbia. Unpublished report for Water Investigations Branch, B.C. Water Resources Service.
Daly, R.A. 1912. North American Cordillera, Forty-ninth Parallel: Geol. Surv. Canada. Mem. 38. Pts. 1, 2 and 3; 1912.
Dawson, G.M. 1878. Explorations in British Columbia: Geol. Surv. Canada, Rept. Prog. 1876-77: pp 16-149.
Dawson, G.M. 1879. Preliminary Report of the Physical and Geological Features of the Southern Portion of the Interior of British Columbia: Geol. Surv. Canada. Rept. of Prog. 1877-78; pp. 96B-101B.
Dobson, H. 1972. Nutrients in Lake Huron (unpublished manuscript. C.C.I.W., Burlington, Ontario).
Ferguson, R.G. 1949. The Interrelations Among the Fish Populations of Skaha
Lake, B.C., and their Significance in the Production of Kamloops Trout (Salmo gairdnerii kamloops jordan). B.A. thesis, Dept. Zool., Univ. Brit. Col., 84 pp. + 6 appendices.
Flannagan, J.F. 1970. Efficiencies of Various Grabs and Corers in Sampling Freshwater Benthos. J. Fish. Res. Bd. , Canada, 27: 1691=1700.
Flint, R.F. 1935a. Glacial Features of the Southern Okanagan: Geol. Soc.. Amer. Bull., Vol: 46; pp 169-193
Flint, R.F. 1935b. White Silt: Deposits in the Okanagan Valley, B.C.: Roy. Soc. Canada, Trans., Series 3. Vol. 29; Sec. 4.
Fulton, R.J. 1965. Silt Deposition in Late-Glacial Lakes of Southern British Columbia: Am. J. Sci., Vol 263; p 553-570
Fulton, R.J. 1969. Glacial Lake History, Southern Interior Plateau, British Columbia: Geol. Surv. Can., Paper 69-37; 14pp.
Grove, P.C. (ed), 1965. Webster's Third New International Dictionary. Merriam & Co., Springfield, Mass. 2662pp.
Hansen, H.P. 1955. Post-Glacial Forests in South Central and Central British Columbia: Am. J. Sci. , Vol 253; No. 11, p 640
Holland, S.S. 1964. Land Forms of British Columbia, a Physiographic Outline: B.C. Dept. Mines and Petroleum Resources Bull. No. 48; 138pp.
Hustedt, F. 1930. Bacillariophyta (Diatomeae), p. 1-466. In A. Pascher (ed.). Die Susswasserflora Mitteleuropas, Bd. 10. Gustave Fisher, Jena.
Hutchinson, G.E. 1957. A Treatise on Limnology, Vol. I; Geography, Physics and Chemistry. John Wiley and Sons Inc., New York; 1015p.
Hyndman, D.W. 1968. Med-Mesozoic Multiphase folding along the Border of the Shuswap Metamorphic Complex: Bull. Geol. Soc. Am., Vol 79; pp 575-588.
Jones, A.G. 1959. Vernon Map-Area, British Columbia: Geol. Surv. Can. Mem. 296.
Kelley, C.C., and R.H. Spilsbury. 1949. Soil Surve of the Okanagan and Similkameen Valley, British Columbia. Rept. 3 of B.C. Survey. The B.C. Dept. Agriculture in cooperation with Experimental Farms Service, Dominion Dept. of Agriculture: 1-88.
Kemp, A.L.W. 1971. Organic Carbon and Nitrogen in the Surface sediments of Lake Ontario, Erie and Huron: J. Sed. Pet.. Vol 41; No. 2, p 537-548.
Larkin, P.A. and T.G. Northcote. 1969. Fish as Indices of Eutrophication, p 256-273 in: Eutrophication: Causes, Consequences, Correctives. Nat. Acad. Sci ., Washington, D.C.
Liebman, H. 1960. Handbuch der Frischwasser und Abwasser-Biologie. Biologie des Trinkwassers, Badewassers, Tischwassers, Vorftuters und Abwasser. II R. Oldenbourg, Munchen, 1149 -.
Livingstone, D.A. 1963. Chemical Composition of Rivers and Lakes. Data of Geochemistry, 6th ed. Chapt. G.; Geological Survey Professional Paper 440-G. Govt. Printing Office, Washington 25, D.C. 61pp.
Mackereth, F.J.M. 1969. A short core sampler for subaqueous deposits. Limnol. & Oceanogr. 14: 145-151.
McHugh, J.L. 1936. The Whitefishes (Coregonus clupeaforms [Mitchill], and Propsopium Williamsoni [Girard] of the Lakes of the Okanagan Valley, B.C. B.A. thesis, Dept. Zool . , Univ. Brit. Col., 84- + 5 figures, 22 plates.
Mathews, W.H. 1944. Clacial Lakes and Ice Retreat in South Central British Columbia: Roy. Soc. Canada, Trans. Vol. 38; Sec. 4, pp 39-57.
Meyer, C. and K. Yenne, 1940. Notes on the Mineral Assemblage of the "White Silt" Terraces in the Okanagan Valley, British Columbia: J. Sed. Petrology: Vol. 10; No. 1, pp 8-11.
Nasmith, H. 1962. Late Glacial History and Surficial Deposits of the Okanagan Valley, British Columbia: B.C. Dept. Mines and Petroleum Resources Bull. 46; 46p.
Nicholson, H.F. 1970. The Chlorophyll-a Content of the Surface Waters of Lake Ontario, June to November, 1967. Fish. Res. Bd. of Canada. Techn. Rept. No. 186; 31pp.
Northcote, T.G. and P.A. Larkin. 1956. Indices of Productivity in British Columbia Lakes. British Columbia Game Commission & University of British Columbia; Vancouver. J. Fish. Res. Bd. Canada 13 (4), pp 515-540.
Papp, 1969. Provisional Algal Assay Procedure, Joint Industry/Government Task Force on Eutrophication. P.O. Box 3011, Grand Central Station, New York, N.Y. 10017; 62p.
Patrick. R. and E.W. Reimer. 1966. The Diatoms of the United States; Vol. 1, Monogr. Acad. Natur. Sci., Phila. 13: 688p.
Reineike, L. 1915. Physiography of Beaverdell Area: Geol. Surv. Canada, Mus. Bull. No. 11 .
Rigg, G.B. and H.R. Goud. 1957. Age of Glacier Peak Eruption and Chronology of Post-Glacial Peat Deposits in Washington and Surrounding Areas: Am. J. Sci.; Vol. 255. pp 341-363.
Saether, O.A. 1970. A Survey of the Bottom Fauna in Lakes of the Okanagan Valley, British Columbia. Techn. Rep. Fish Res. Bd. Canada; 196. 1-26 and 1-17
Sakamoto, M., 1971. Chemical Factors Involved in the Control of Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. Canada 28: 203-213
Schindler. D.W. and S.K. Holmgren, 1971. Primary Production of Phytoplankton in the Experimental Lakes Area, Northwestern Ontario and Other Low-carbonate Waters, and a Liquid Scintillation Method for Determining C Activity in Photosynthesis. J. Fish. Res. Bd. Canada 28: 189-301.
Shah, R., J.K. Syers, J.D.H. Williams and T.W. Walker, 1968. The Forms of Inorganic Phosphorus Extracted from Solids by N Sulfuric Acid: N.Z. Journal of Agricultural Res., Vol. 11; No. 1, 184-192.
Sismey, E.D. 1921. A Contribution to the Algae Flora of the Okanagan (British Columbia). Canadian Field Nature. 35: 112-114
Sladeckova, A. 1963. Aquatic Deuteromycetes as Indicators of Starch Campaign Pollution. Intern. Rev. Hydrobiol. 48: 35-42.
Stein, J.R., and T.L. Coulthard, 1971. Water Quality Deterioration in Osoyoos Lake, British Columbia. Unpublished report for Water Investigations Branch, B.C. Water Resources Service.
Stockner, J.G. and F.A.J. Armstrong. 1971. Periphyton of the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. of Canada, 28: pp 215-229.
Stockner, J.G. and T.G. Northcote, 1974. (in press). Recent Limnological Studies of Okanagan Basin Lakes and their Contribution to Comprehensive Water Resource Planning.
Sverdrup, H.V., M.W. Johnson and R.H. Fleming, 1942. The Oceans; their Physics, Chemistry and General Biology. Prentice-Hall, Englewood Cliffs, N.J., U.S.A. 1098 pp.
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Vollenweider, R.A., 1969. Mogiichkeiten und Grenzen Elementarer Modelle der Stoffbitanz von Seen. Arch. Hydrobiol. 66: 1:1-36.
Westgate, J.A., D.G.W. Smaith and M. Tomlinson, 1970. Late Quaternary Tephra Layers in Southwestern Canada: In Early Man and Environments in Northwest North America: Univ. of Calgary Archaeol. Assoc., The Students Press; Calgary; pp 13-34.
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Williams, J.D.H., J.K. Syers, and T.W. Walker, 1967. Fractionation of Soil Inorganic Phosphorus by a Modification of Chang and Jackson's Procedure: Soil Science of America Proceedings: Vol 31; No. 6, 736-739pp.
Woodridge, C.G. 1940. The Boron Content of some Okanagan Soils: Sci. Agr. XX:5.
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Yentsch, C.S. and D.W. Menzel. 1973. A Method for Determination of Phytoplankton Chlorophyll and Phaeophytin by Fluorescene. Deep See Res.; 10:
221-231.
CHAPTER 2 Study Area Description
The Okanagan River Basin extends from north latitude 59° 50' in close
proximity to Shuswap Lake. Flow is in a southerly direction for 127 miles in
Canada and 73 miles in the United States to its confluence with the Columbia
River. The main valley lake system is comprised of six lakes interconnected by
river flow (Figure 2.1). Wood-Kalamalka Lakes sub-basin discharges via Vernon
Creek to Vernon Arm of Okanagan Lake. The outflow of Okanagan Lake becomes
Okanagan River which flows south, connecting Skaha, Vaseux and Osoyoos Lakes
(Figure 2.1). From Wood Lake to Osoyoos Lake the elevation drops 371 feet from
1,284 to 913 feet (MSL).
Basic data pertaining to drainage basin area, major land use practice,
climate, hydrology and population are supplied in Table 2.1. In general, the
Okanagan Valley is - shaped, with mountains rising 4,000 to 7,000 feet on
both sides. Bench lands 100-200 feet above the lakes are a conspicuous feature
of valley topography. The soil of the bench lands is good for fruit crops. The
bottom lands adjacent to the Okanagan River are used for dairy farming and grow-
ing fruits and vegetables. The higher, open forest lands are grass covered,
providing open range land for cattle and ungulate grazing as well as timber
production.
While the entire valley lies in a dry belt, there is a gradual change in
climatic conditions from south to north (Table 2.1). At Oliver in the extreme
southern part of the Valley, average rainfall is 10.8 inches per year, while at
Armstrong in the extreme north, it is 17.2 inches per year. Maximum temperatures
in July/August may reach 11O°F, while minimums of -20°F are not uncommon in
January. There are approximately 152 frost-free days at Oliver, but only 114 at
Armstrong.
Most of the main valley lakes are ice-covered in winter, generally from late
December to the middle of March. Okanagan Lake seldom has a complete ice cover,
but the bays and shallow inlets are often frozen over for long periods,
The majority of inflow water to the lakes comes during a three month period
from April to June. Except for major tributary streams, most small streambeds
are dry from July to November, due chiefly to upstream storage and irrigation
demands. It is estimated that of an average annual gross inflow of 664,000 acre
feet to Okanagan Lake Basin, up to 1/3 is lost by evaporation and transpiration
from Okanagan Lake. About 15% of the mean annual surface runoff to Okanagan Lake
is used for irrigation.
There are three major population centers in the Basin: Vernon, Kelowna and
Penticton (Figure 2.1). The major industrial developments in the valley are
associated with the agricultural, tourist and forest industries. Current
population (1971 census) in the Valley is about 114,500 people.
TABLE 2.1
BASIC DATA ON OKANAGAN VALLEY DRAINAGE BASIN
CHAPTER 3 Methods and Approach
3.1 GEOLOGICAL STUDIES
Information pertaining to basic geologic formation, sediment
characteristics of lake bottoms, sedimentation rate arid basin contours was
required for numerous portions of the study as basic background data. Much
information, particularly basic geology, is available from other
investigators. This was used where applicable. Where documentation was
lacking, studies were carried out - particularly with regard to contour
mapping, sediment core sampling, element analysis and paleolimnological
examination.
Field work was carried out during the summer and fall of 1971. An
acoustic sounding program took place on the main valley lakes. In
addition, a transit sounder survey of the near-shore areas of Skaha and
Southern Okanagan Lakes was performed. Over 150 surface samples (0-3 cm.)
were collected with a Skipek grab sampler (Figure 3.1). About 50 one meter
cores were taken with a benthos corer. All sediment samples were freeze
dried in the field after observations of color, texture and general
characteristics were noted. Water depth and position of each sample was
recorded. Measurements of hydrogen ion concentration (pH), oxidation-
reduction potential (Eh), and water content of cores were made in August of
1971.
Samples collected were subjected to a variety of laboratory
procedures, and methods employed are detailed below.
Total major element analysis of samples was done by X-ray fluorescence
using a Phillips PW1220C semi-automatic X-ray fluorescence spectrometer on
pelletized samples. Ca, Na, Fe, Mg, P, Mn, Si, K, S, Al and Ti were
determined with this system. HCl, extractable Pb, Fe, Mn, Cu, Zn, Ni, Co,
Cr, Cd, Be, V, K, Mg and Ca, were measured by a Techtron AA-5 Atomic
Absorption Spectrophotometer. The freeze dried sediment samples were
subjected to attack by hot concentrated HCl for 30 minutes and the leachate
was analysed.
Additional trace element results were obtained under contract to the
Commercial Products laboratory of the Atomic Energy Commission, Ottawa.
This laboratory analysed perchloric acid leaches from the sediments of Cu,
Mn, As, Sc, Eu and Sm using instrumental neutron activation analysis.
Mercury analyses of the sediment were made by Barringer Research of
Toronto, using their patented mercury spectrometer. Differential thermal
mercury analysis of selected samples were done by Barringer Research to
assist in characterizing the forms of mercury in the sediments.
Organic carbon and carbonate carbon contents of the sediment were
measured using a Leco induction furnace according to the method described
by Kemp, 1971.
Acid extractable phosphorus was determined by a modification of the
method of Shah et al, 1968. The modification consisted of the use of HCl
in place of H2S04.
The grain size fractionation of the sediments was measured by standard
long pipette analysis. X-ray diffraction studies were undertaken on the
mineralogical composition of each size fraction, and this work was assisted
by microscopic investigation.
Two short cores were obtained from Skaha Lake for diatom
paleolimnological analysis (Figure 3.2). Core SK2 was obtained with a
Mackereth corer (Mackereth 1969) in 1970, at a water depth of 6 meters, and
Core SK1 was obtained with a gravity corer in 1971 at the area of maximum
water depth - 60 meters. Both cores were sectioned within a week of
obtaining them. Core SK2 was 45 cm. long and was sectioned at 0.5 cm.
intervals to 10 cm., and at 1.0 cm. intervals for the remainder. Core SK1
was 105 cm. long and was sectioned at 1.0 cm. intervals to a depth of 20
cm. and at 5.0 cm. intervals for the remainder. Samples were obtained from
the non-smeared inner portion of each section. Loss of weight on ignition
(L.O.I.) values were determined for Core SK1 by burning oven-dried samples
in a muffle furnace at 500°C for two hours.
Approximately 1 gram of fresh sediment from each core was macerated in
concentrated, diluted nitric acid. Samples were boiled until they reached
half the original volume, then K2Cr2O7 was added for final oxidation. The
samples were repeatedly decanted, rinsed, and allowed to resettle until no
trace of acid remained. Permanent slides were made. Approximately 300 to
400 diatom frustules per slide were examined microscopically. The
monographs of Hustedt 1930, Cleve-Euler 1951 and Patrick and Reimer 1966
were used for identification, the more common diatoms being identified to
species, other to genera.
Data were processed on an IBM 360 computer at the University of
Manitoba Computer Center. Output gave percentage composition of the total
diatom populations for all species, the Order Centrales, and the four
Pennate tribes represented. Computer output data for the relative
abundance of each species, genus, and group enumerated from the sediment
cores were plotted by a Calcomp digital plotter as a function of sediment
depth.
3.2 PHYSICAL STUDIES
Data pertaining to temperature, heat content and light transmittance
of lake waters are essential to adequately determine the trophic state of
lakes. By comparison with established criteria, the dynamics of
eutrophication rate
can be assessed. Physical studies involved data collection from the main valley
lakes with regard to temperature, heat content and light transmittance and a
study of the dispersion of the Okanagan River plume into Skaha Lake. Lake temp-
eratures and light penetration was monitored in 1971, based on sampling stations
established by study personnel. Numbers of stations, shown in Maps 3 to 10* in
the Map Section at the back of this report, varied with lake size and complexity.
(i.e. - 4 stations in Wood Lake, 19 in Okanagan Lake).
Temperature data were obtained with bathythermographs which were accurate to
within ± 0.5°C for temperature and ± 1% of the scale used for depth. Monitor
cruise data were supplemented with information from Ryan 15-day continuously
recording thermographs in each lake (Maps 3 to 10). Ryan accuracies were ± 1°C
and ± 1 to 3 hours in 15 days, depending upon the individual instrument.
Light transmittance data were collected on all lakes in September 1970 and
May 1971 with submarine photometers. In 1970, a Model C-10 Irradiance and Depth
Meter, manufactured by Marine Advisors, Inc., was used. A set of three Kodak
Wratten filters (Red #29, Green #58 and Blue #47) were used with maximum trans-
mission as suggested by Vollenweider (1969). In May 1971, a Kahl Scientific
Instrument submarine photometer, Model 368 WA310 was used.
To calculate heat content and synthesize bathythermograph data, a Fortran
IV program was used to calculate:
1) the average value of temperatures in the hypolimnion, meso-
limnion and epilimnion
2) volumes of thermal layers, and
3) heat content of the layers.
The three heat contents were summed to give lake totals.
The input data consisted of:
1) cards punched in the format presently prescribed for
digitized bathythermograph data at C.C.I.W., and
2) digitized mean depths of a system of grid squares super-
imposed on each lake.
The table below compares digitized lake volumes with volumes determined from a
hyposometric curve.
Okanagan Lake data were synthesized manually because the long shoreline
development would have required a subdivision of the lake into segments, thereby
sacrificing efficiency gained by using the Fortran IV program.
* Maps 1 and 2 are called up later in text.
To calculate light transmission values, the percent attenuation of
light versus depth were plotted on semi-log paper, placing depth on the
linear scale (Vollenweider, 1969). The extinction coefficient, (m-1) was
then converted to transmission of light, T (%/m) by the formula:
T = 100 e-•
where: • is the slope of the line connecting the percent attenuation versus depth points.
During September, 1970, when Red, Green and Blue filters were used, T was
calculated according to the formula:
T = 1/3 (T630 + T530 + T450)
where: T530, T530, T450 are the transmission values in %/m for
the Red, Green and Blue filters respectively.
The effluent from the Penticton sewage treatment plant is discharged
into the Okanagan River above Skaha Lake. It was thus considered of value
to determine the fate of this river plume as it enters the lake, since
nutrient dispersal may follow a similar pattern. Water soluble Rhodamine B
dye was used to tag the river water. After determining the natural
degradation rate of the dye in Okanagan River water, solutions were
adjusted to specific gravity 1.00 and released into the midstream, 400 feet
upstream from the river mouth.
Dye diffusion was monitored in the lake vertically and horizontally.
Fluorometers were used to measure dye concentrations. Tracking drogues at
a variety of depths measured currents. Wind data were obtained from the
Penticton Airport, adjacent to the study site.
3.3 CHEMICAL STUDIES
Knowledge of the chemical characteristics of lake waters are required
to determine the trophic state and potential productivity of a water body.
Okanagan main valley lakes were chemically examined from 45 stations during
1971, (Maps 3 - 10). Temperature, Secchi disc measurements and lake water
samples for chemical and biological analyses were collected at 23 "chemical
stations" while
temperature and Secchi disc measurements only were made at the remaining
22. Sampling dates were approximately bi-monthly, with two extra samplings
in May and July, (Table 3.1). Sampling dates included spring and fall
overturns and full summer stratification.
Water samples were collected during isothermy with a 3 liter Van Dorn
sampler at 5, 10, 25, 50, 100 meter depths, and at two meters from the
lake bottom. If stratification was noted, samples were taken at two
depths in the epilimnion, two or three depths in the mesolimnion
(depending on steepness of gradient) and three depths in the hypolimnion.
Samples for chlorophyll-a analysis were taken one meter below the surface
and one meter above and below the mesolimnion if stratification prevailed.
During isothermy only the one meter below surface sample was collected.
Upon retrieval; dissolved oxygen content, conductivity and pH were
determined. One liter samples in plastic bottles were then forwarded in
ice to the Mater Quality Division Laboratory in Calgary where chemical
analysis took place within 24 hours of sampling. These samples were
analyzed for: nutrients, NO3(N), Total Kjeldahl -N, Ortho-PO4, Total P
(reported as PO4), SiO2 major ions; Ca, Mg, K, Na, CO3, HCO3, S04, Cl, F;
total dissolved Iron and heavy metals Cu, Zn, Pb, Mn; total organic carbon;
total inorganic carbon; pH, alkalinity, total hardness, conductivity,
turbidity, and color. The water Quality Division's field laboratory in
Kelowna analyzed another liter sample for pH, conductivity, alkalinity, BOD
-5, suspended solids and turbidity . All the above analyses were done
using methods outlined in APHA Standard Methods (1965).
Chlorophyll-a analysis was carried out in the laboratory in the Basin
Study office in Penticton. Samples were filtered, dried in a dessicator
and analysed fluorimetrically after tissue grinding and acetone
extraction(Yentsch and Menzel, 1963).
3.4 BIOLOGICAL STUDIES
Because the quantitative and qualitative aspects of lake biology
represent the results of physical, chemical, meteorological and geological
factors and interactions, the biological aspects of the main valley lakes
were examined in some detail. Nutrient bioassay, macrophytes, periphyton
studies, bottom fauna, zooplankton and fish studies were all undertaken.
The purpose and methodology for each biological facet examined are outlined
below.
3.4.1 Nutrient Bioassay
Photosynthetic production, while providing a "food base" for other
Okanagan main valley lakes biota, can become a nuisance factor to man and
accelerate eutrophication if not maintained in check. An adequate
understanding of the role
TABLE 3.1
SAMPLING DATES, OKANAGAN BASIN LAKES CHEMISTRY PROGRAM
of various nutrients in regulating algal growth in the lakes was therefore
considered essential to the limnology program and studies were designed to
test the effects of PO4(P), NO3,(N) and CO2 on stimulating algal growth in the
Okanagan main valley lake waters.
(a) Nutrient Enrichment
Nutrient enrichment experiments were carried out using Okanagan main
valley lakes water and natural phytoplankton populations during spring and
fall of 1970 and 1971. Surface water samples were collected from mid-lake
stations in Skaha, Osoyoos, Okanagan, Wood and Kalamalka Lakes in 1970, (Maps
3 - 10). Vaseux Lake was added to the series in 1971. An additional 500 ml.
sample was collected and preserved (Lugol's solution) for phytoplankton
identification. In 1970 a further sample was taken and analysed for
alkalinity, conductivity, nutrients, pH, T.O.C., and turbidity, as this was
prior to the inception of the chemical limnology program.
Upon returning to the laboratory a 6 liter water sample was filtered
through an 87 micro-mesh net to remove zooplankton. The sample was then div-
ided into 100 ml. aliquots, each of which was placed in a 250 ml. Erlenmeyer
flask. Nutrient additions were then made with sterile micropipettes in
concentrations outlined in Table 3.2. One micro-curie of Na14CO3 was added to
each flask to monitor relative photosynthetic carbon uptake. The cultures
were illuminated by a light bank (1750 foot candles, 18,830 lux) from below
for 15 days. During the spring of 1970 temperature was not kept constant,
varying between 25° and 33° C.
Starting on August 12, 1970, incubation took place under more closely
controlled conditions. Temperature was a constant 24° +°C. Flasks #2, 6, 7,
8, 9, 10, 12, 17 and 22 (Table 3.2) were eliminated and only Okanagan, Skaha
and Kalamalka Lakes were sampled. All samples were accommodated over one
light bank of 400 foot candles (4,304 lux) intensity.
The cultures were gently swirled twice daily and a 10 ml. sub-sample
taken every 5 days. The sub-sample was filtered through a 45 micro-millipore
filter and washed with distilled water. The filters were placed in
scintillation vials containing 20 ml. of scintillation fluid (Schindler and
Holmgren, 1971).
Photosynthetic carbon uptake for each culture was recorded as counts per
minute (cpm) by means of the Packard Tricarb Scintillation counter at FRB
Laboratories, Vancouver, B.C. The relative growth rates monitored in this
way provided a measure of activity for comparison among cultures in each
experiment.
After 15 days' growth the experiments were terminated and the remaining
portion of the cultures were sampled as follows: 10 ml. for measurements of
carbon uptake as cpm; 20 ml. filtered through a glass filter for chlorophyll-
a.
TABLE 3.2
CONCENTRATIONS OF NO3(N) and PO4(P) and CO2 USED
IN NUTRIENT ENRICHMENT BIOASSAY
analysis; 20 ml. placed in a vial with Lugol's solution for algal
identification; and the remaining 30 ml. filtered through a 0.45
Millipore filter and dried between Parafilm sheets. These filters were later
photographed for a pictorial representation of the relative effects of the
various nutrient additions on algal growth.
Results of C14 measurements were calculated using the following
formula:
T.C.P.M. = cpm x (10-x) + cumulative cpm.
As the sub-sample was 10 ml. the cpm was multiplied by 10 to give the total
cpm of the culture (TCPM). However, after the first subsample (10-x) was
used, x being the total number of 10 ml. samples removed. The cumulative cpm
was the total of all radioactivity removed from the culture in earlier
samples.
During 1971, further procedural modifications were made. The six liter
sample was subdivided into 150 ml. aliquots and duplicate series were run.
Nutrient concentrations differed in some respects (Table 3.2). Slightly more
(1.5 micro-curie) C14 was added to compensate for increased volume of water.
The experimental period was shortened to 9 days since 1970 studies showed
growth reached optimal levels after 7-9 days. Subsamples were withdrawn at
2-day intervals containing 15 ml. of Aquasol scintillation fluid. On the
ninth day, the experiments were terminated as follows: 90 ml. for
chlorophyll-a. determination, 20 ml. for algal determination and 70 ml.
filtered for photographic interpretation.
(b) Pure Culture Bioassay
By removing all phytoplankton from take waters and introducing a known
species at a known concentration to lake water under controlled conditions,
it is possible to determine, at least on a comparative basis, the latent
productive capacity of the waters examined. It was assumed this experiment
would yield some insight into what specific regions or water masses within
lakes contained residual nutrients stimulatory to test algae.
The following organisms were used to inoculate lake waters:
1. Selenas capricornutum (Chlorophyta).
2. Anabaena flos-aquae (nitrogen fixing Cyanophyta).
3. Microcystis aeruginosa (non-nitrogen fixing Cyanophyta).
The inocula were produced and maintained by transferring them every seven
days to defined algal nutrient media (Paap, 1969). These cultures were kept
at constant temperature (24 ±l°C, 1970; 21±°C, 1971) on a light bank (400
foot candles, 1971) and swirled at least four times daily.
In preparation for the experiments, water samples were collected from
five main valley lakes in 1979 (Vaseux excluded) and from all main valley
lakes in
1971. One liter samples were collected from stations indicated in Maps
3 to 10.
Upon return to the laboratory, water samples were filtered through 0.45
micro-millipore filters to remove all plankton. Six 100 ml, sub-samples of
filtered water were placed in six 250 ml. sterilized Erlenmeyer flasks. Two
ml. of synchronous 7 day old Selenastrum inocula plus 1.0 micro-curie of
Na14CO3, was added to each of two flasks. Additives of Microcystis plus Na14CO3
and Anabaena plus Na14CO3 in the same amounts were added to two other pairs of
flasks. Thus, a monoculture growth series was established in duplicate.
Similar flasks for each test organism were prepared, but instead of lake
water a defined algal nutrient medium was used. These flasks, containing 50
ml. of nutrient medium, 1.0 ml. of culture inocula and 1.0 micro-curie of
Na14CO3 were used as controls.
The cultures were placed on a light bank (400 foot candles) and either
swirled 4 times daily or shaken continuously at 80 oscillations per minute.
In 1970, the experiments were of 9 days' duration, while in 1971 a seven day
experimental period was used. Every second day, light absorbance and trans-
mittance at 600 mu was measured. Photosynthetic carbon uptake was monitored
every second day in 1971. In 1971, sub-sampling included chlorophyll-a
analysis.
(c) Sewage Effluent Experiments
In 1971 a sewage effluent experiment was conducted in an attempt to gain
insight into effects sewage enrichment might have on natural phytoplankton
populations of five (Vaseux Lake excluded) Okanagan main valley lakes. It
was also designed to test the effectiveness of tertiary treatment facilities
currently in operation at the Penticton sewage treatment plant.
Surface water from each lake was obtained from an area free of the direct
effluent influence (Maps 3 to 10). Sewage was collected from the Penticton
sewage treatment plant in the following states:
1. raw sewage
2. after primary treatment
3. mixed liquor
4. non-chlorinated post secondary
5. chlorinated post secondary
6. chlorinated post tertiary
Removal of PO4(P) at the time of sampling was estimated to be between 40% and
50%.
Laboratory procedure was identical to that of the 1971 nutrient
enrichment experiment, except that varying amounts of sewage were added to
each flask instead of defined nutrients (Table 3.3).
TABLE 3.3
CONCENTRATIONS OF PO4(P) AND NO3(N) USED
IN SEWAGE ENRICHMENT EXPERIMENTS
1. Values of Raw and Secondary from Penticton Sewage Treatment Plant
laboratory, other from Mr. Archie Pick, Winnipeg Metro Sewage works. All
NO3(N) values from Metro Winnipeg STP.
2. Assumes 45% reduction at Penticton Plant which was the case at time of
sampling.
(d) Trace Metal Experiments
These experiments were designed to test the effects of the nutrients NO3(N)
and PO4(P) in combination with some trace metals and the chelator EDTS on the
growth of natural phytoplankton populations in five of the Okanagan Basin Lakes.
Samples were obtained from the surface waters of the five major lakes,
Vaseux Lake excluded (Maps 3-10). These samples formed the basis for sixty-three
flasks, which included seven for the fall run of the nutrient bioassay. The
procedure was identical to that of the 1971 spring nutrient enrichment experiment
except that nutrients and trace metals were added in different concentrations and
combinations (Table 3.4).
3.4.2 Periphyton and Rooted Aquatic Vegetation
The trophic state of the lake often manifests itself in the density and
variety of rooted aquatic vegetation that grows in the littoral area and the
algae that in turn uses the macrobenthos and other littoral substrate for attach-
ment. In lakes which are abundantly supplied with nutrients and a suitable sub-
strate, these plant forms may reach nuisance densities and restrict water use in
a number of ways. The extent of this growth in the Okanagan main valley lakes
was examined in 1972, as was the determination of biomass and relative growth
rate of periphyton. Four glass slides were suspended on a plexiglass tray
(Figure 3.3) at 1.5 meter depth in selected stations in each lake. (Maps 3 to
10). Slides were removed from the trays at biweekly intervals, placed in glass
jars with distilled water and transported to the laboratory. Two slides were
scraped onto a preweighed Sartorius membrane filter (o.45 microns) and dried in a
desiccator overnight. A third slide was scraped, filtered onto a Whatman GFC
glass fiber filter, and macerated in a tissue grinder with 10 ml. of acetone.
The extract was measured for chlorophyll-a. content using fluorometic methods
(Nicholson, 1970). The last slide was scraped, filtered onto a Whatman filter,
dried overnight and frozen. Total phosphorus was determined at the FRB-FI,
Winnipeg laboratory using methods described by Stockner and Armstrong (1971). A
few stations were chosen for a complete chemical tissue analysis -including total
carbon and total nitrogen, as well as total phosphorus.
A strip of periphyton was removed from the plexiglass tray at each sampling
period and analyzed for species composition. The same strip was repeatedly sam-
pled, thereby reducing the likelihood of sampling more advanced stages of succ-
ession. At the laboratory, Lugol's solution was added and the samples were
stored in small glass vials to await microscopic analysis. Upon examination, up
to four glass slide mounts were made of each sample. If little variation was
observed on two successive slides, no further examination was carried out.
However, if considerable variation was encountered on the first two slides, an
additional two were examined. The percentage composition of the major algal
phyla, together with a list of dominant species was prepared. Absolute counts
were not performed. Since species composition and growth on glass slides may be
different than on
TABLE 3.4
TRACE METAL, CHELATOR AND NUTRIENT ADDITIONS, 1971
APPARATUS USED TO COLLECT PERIPHYTON IN THE OKANAGAN
MAIN VALLEY LAKES Figure 3.3
plexiglass (Sladeckova, 1963), later in the summer a fifth slide was attached
to the tray to allow this comparison to be made. The extent of the littoral
zone was estimated using Secchi disc measurements and direct underwater
photometer light readings. Air color photos of each lake were also used to
better define the littoral zone. The substrata were identified by
observation from a boat or with an Ekman grab. Macrophytic vegetation was
collected by hand, placed in jars with 10% formalin, and later tentatively
identified. By midsummer it was apparent that extensive collections from
each lake could not be completed in the time allotted and the major aquatic
vegetation was therefore lumped into three groups for mapping: Floating
leafed, submergent vegetation, and emergent vegetation. The size of weed
beds was estimated first with a range-finder, followed by several transects
through the beds by boat. Small patches of vegetation were noted by visual
observation as the boat followed the shoreline of each lake at a very slow
speed. All observations were recorded on a rough base-map and later
transferred to a field notebook. Some vegetation was sampled by diving.
Base maps with major substrates were drawn to scale at the Study Office.
Separate maps designating the dominant vegetation were drawn to the same
scale as the base maps to serve as overlays.
3.4.3 Bottom Fauna
Bottom fauna (bottom living invertebrate animals) serve as valuable
indicators of trophic conditions in lakes. For several decades limnologists
have studied the relation between density and species composition of
invertebrates living in the bottom sediments of lakes exhibiting a wide
variety of trophic as well as morphological characteristics. Because bottom
fauna tend to be sedimentry organisms, they often integrate temporal,
environmental change thus serving as sensitive barometers of lake change.
Benthos samples were collected September 9 to 11, 1969 and May 10 to 12
in 1971 from the main valley lakes (Maps 3 to 10). In Skaha Lake the
sampling sites were essentially the same as those taken during the 1969
survey (Saether, 1970), with the addition of one sampling site in the south
basin. In Kalamalka and Wood Lakes, the sample sites were chosen near inlets
and outlets with additional samples taken from the deep parts.
A new improved Ekman sampler (Burton and Flannagan, 1973) was used. The
samples were sieved through an 0.2 mm. mesh size whenever possible, and in
selected samples, through a 0.6 mm. mesh size sieve. In most cases the
sediments filled up the samplers to about 2.5 inches from the top, the
preferred level mentioned by Flannagan (1970). Some littoral samples
contained only a couple of inches of sediment, mostly of sand and/or
vegetation. All samples were preserved with 4% formalin and examined in the
laboratory where animals were identified and densities calculated.
3.4.4 Zooplankton
Zooplankton populations, while highly variable seasonally, are nonetheless
dependent on lake trophic character for their expression. Zooplankton species
and densities can be used to typify the trophic status of lakes and also
monitor changes in productive capacity. Zooplankton analyses in the Okanagan
main valley lakes was carried out with a view to providing basic data and
providing a comparison with the data collected by earlier workers.
Okanagan Lake was sampled on September 9 and 10, 1969 and August 26 and 27
of 1971 at three points on each of 10 transects, (Map 2). In Skaha lake, three
stations were sampled on both September 11, 1969 and August 24, 1971.
representing the northern, central and southern parts of the lake. On the same
days, one station was sampled in the middle of each of the north and central
basins of Osoyoos Lake. Kalamalka and Wood Lakes were sampled only once on
August 25, 1971 at five and two stations, respectively. A Wisconsin type
plankton net (mesh opening 77 microns) with a 25 cm. diameter mouth was used at
each station to obtain vertical hauls from a depth of 50 meters to the surface,
or from just above the bottom to the surface at stations shallower than 50
meters. In addition, 0-5 meter hauls were made on August 25-26, 1971 on
Okanagan Lake to study the differences between inshore and offshore plankton.
At each of the inshore stations, four 0-5 meter vertical hauls were made
perpendicularly to the shoreline spaced at 50 meter intervals beginning from
the point with a water depth of 5 meters. One 0-5 meter haul was made at each
offshore station located in the middle of the west-east lake transect. Samples
were collected at 5 meter intervals within 4 separate layers: 0-25, 25-50, 50-
75 and 75-100 meters, using a transparent 5 liter van Dorn bottle. The samples
within each layer were combined and filtered through a No. 20 plankton net,
preserved in a 2% formaldehyde solution and analysed using a subsampling
technique with at least 200 specimens per subsample being counted. Zooplankton
abundance was expressed as the number of 2 specimens per 1 cm2 of lake area,
assuming the filtration efficiency of the net to be 100%. The counts of
rotifers do not include all forms due to a loss of smaller specimens through
the 77 micron mesh size netting. The plankton volume collected at each station
was measured by settling in Imhoff sedimentation cones prior to specimen
enumeration. In addition, at all stations temperature profiles were recorded
and dissolved oxygen, TDS, Ca, Mg, Na, K, Cl and water transparency were
measured.
3.4.5 Fishes
Fishes are often the top of the aquatic food web in fresh water lakes and
as such can serve as convenient indicators of trophic lake state. While
variability is high, due to the vast number of factors acting upon higher level
consumers, data derived from a standard approach can elucidate valuable trends
and trophic status. It was with this in mind that the main valley lakes
fishing sampling project was undertaken.
Standard netting stations were established on the study lakes (Figure 3.4),
early in April, 1971. For the smaller lakes one or two stations were located
near the deeper basins but for Okanagan Lake they were spread out to cover the
northwest arm (1 station), and the northern area (2 stations), the central area
(3 stations) and the southern area (2 stations). Despite attempts to place
stations over only moderately sloping bottom, there was wide variation in bottom
profiles between stations (Figure 3.4). Often other considerations (marinas,
swimming beaches, shipping, and boating lanes, etc), dictated station location.
At each station standard series of gill net sets were made (Figure 3,4). All
gangs were set approximately parallel to shore, following the designated depth
contours. At the 2.5 and 7.5 meters (8 and 25 feet) contours, nets of those
respective depths were set; at the 15 meter contour (ca 50 feet), surface and
bottom gangs each 7.5 meters deep fished the whole depth zone. At the 30 meter
contour (ca 100 feet), floating and bottom gangs each 7.5 meters deep, left a 15
meter midwater stratum unfished. Further offshore at 7.5 meters deep, gang was
set at the surface to fish the upper layer only. Each gang consisted of 6 mesh
sizes - 38, 51, 63, 76, 102 and 127 mm. stretched mesh (1.5, 2, 2.5, 3.4 and 5
inch) with 15 meter (50 feet) of each mesh size. The webbing was made of 0.20
mm. diameter monofilament nylon (Grylon fiber). The nets were set in the evening
and lifted in the morning, fishing for about a 12 hour overnight period. A spring
(May 2-23), summer (July 19-August 10) and autumn (October 2-November 3) series
was run, each station received the complete standard net set once during the
seasonal period indicated. Other sets were made periodically over the year to
obtain additional samples.
An echo sounder tracing was usually made around the whole netting area
(Figure 3.4) in the evening after the nets were set, and again in the morning
before they were lifted. A 50 Kc/second Furuno F701 sounder was used. In con-
junction with each standard netting station (spring and autumn only), one or two
beach hauls were made in late evening with a 32 mm. seine. The seine had a
central panel of 6 mm. stretched mesh 6 meters in length and depth joined at each
end by a 2.4 meter length (6 meter deep) of 12 mm. stretched mesh and a 10 meter
"wing" section of 25 mm. mesh which tapered to 0.9 meters in depth at the bridle
end. All webbing was knotless green nylon.
Fish were left gilled in the nets when lifted and were removed onshore later
in the morning, the catch from each gang (but not each mesh size) being recorded
separately. Usually the total net catch of each species was measured (fork
length in mm.), and many were weighed to the nearest gram. Sex was recorded
routinely where it was obvious from the state of maturation and occasionally by
internal examination. Scales were taken for aging from most species as described
by McHugh (Ms 1936) and Clemens et al (1939). Otoliths were taken from burbot as
well as from a few other species (lake trout, kokanee).
Fish captured by seining were usually preserved in a 10% formalin solution,
although large individuals often were sampled similarly to netted fish. Small
fish (•150 mm.) made up the bulk of the seine catch and these were measured,
weighed and scale samples (where feasible) obtained in the laboratory. No ad-
justments in length or weight were made for changes, which might have occurred
during the preservation period (<9 months at the most).
The survey was conducted entirely in 1971, starting in April and ending in
December. Information from recent years was available from files of the British
Columbia Fish and Wildlife Branch. Earlier data were obtained from a summer
study on Skaha Lake (Ferguson, MS 1949), and from the work of Clemens and others
on the basin in 1935 (Clemens et al 1939; McHugh, MS 1936).
All data were transferred from original field sheets or earlier reports to
Fortran coding forms and then single computer cards were punched for each indiv-
idual fish to maximize flexibility of analysis. A total of 23,288 fish were
analyzed; 1,257 from 1935; 2,406 from 1948; 755 from 1949 to 1970 and 18,870 from
1971.
CHAPTER 4 Geology of the Main Valley Lakes
4.1 PREVIOUS WORK
The earliest publications concerned with the geology of the Okanagan
Valley are those of Dawson (1878, 1879) and Daly (1912). More recent work
on bedrock geology has been reported in Cairns (1932, 1937, 1949); Jones
(1959); Hyndman (1968); and on the maps (annotated) GSC (1940); (1960 and 1961).
Surficial geology and Pleistocene history has been discussed in Flint
(1935 a,b), Meyer and Yenne (1940), Mathews (1944), Nasmith (1962), Wright
and Frey, (1965); Armstrong et al, (1965), and Fulton (1965, 1969, and
1971). The works of Nasmith (op. cit), and Fulton (op. cit)provide the
most complete discussions of the Pleistocene history of the area.
Soil types of the Okanagan Valley have been discussed by Woodridge
(1940) and Kelly and Spilsbury (1949). Hansen (1955) published valuable
work on pollen geochronologies in peat deposits from southern B.C., and his
work provides a background for present Okanagan Valley pollen studies.
Volcanic explosion ash bands have been used with success in geologic
studies in the B.C.-Washington border area. Information on these ash bands
has been published in Rigg and Gould (1957), Wilcox (1965), and Westgate,
et al (1970). Publications on ash band chronology have been reviewed by
Fulton (1971).
Geomorphological aspects of the Okanagan area have been
discussed in Reinecke (1959), Holland (1964), and Tipper (1971).
4.2 RESULTS
The Okanagan Valley is a structural trench overlying a system of
subparallel, linked faults that separate the late Paleozoic or early
Mesozoic Monashee group of metamorphic rocks of differing lithology, but of
similar age. This trench is partially filled by several hundred feet of
unconsolidated material. The thickness of this unconsolidated material
varies, but typical minimum thickness under the centers of the lakes are
presented in Table 4.1. The trench is apparently continuous under the
Okanagan River between Skaha and Okanagan Lakes as well as under Vernon
Creek between Wood and Kalamalka Lakes.
It is likely that the unconsolidated material in the trench was
deposited in association with the earlier glaciations of the Pleistocene
Epoch. The nature of the deposits is uncertain from seismic records alone,
but it seems
probable that during the Pleistocene, the Valley was the site of deposition
resulting from glacial outwash, direct glaciation and Lacustrine fluvial
sedimentation. During deglaciation, a number of terraces were formed as the
lowering of post-glacial lake levels was repeatedly arrested. A previously
undiscovered terrace 50 feet below the present lake level appears to be a
remnant of a low stand of Okanagan and Skaha Lakes.
The prominent silt and clay cliffs that border Skaha Lake and southern
Okanagan Lake were formed during this period of glacial downwashing and degrad-
ation (Flint, 1935). Fulton (1969) has estimated that the deglaciation of the
interior plateau of British Columbia was well advanced by 9,750 B.P. (Before
Present), and by 8,900 B.P. all ice was melted and glacial lakes had been
drained. From this time to the present day, the main valley lakes of the
Okanagan have been in existence. Data from these studies do not allow a direct
calculation of the total accumulation of recent lake sediment, but if one uses a
sedimentation rate of 1 mm. of compacted sediment per year, this would yield an
accumulation of 8.9 meters of sediment in 8,900 years.
Bathymetric charts have been constructed from soundings gathered as part of
the geological study (Maps 3 to 10). Wood Lake is the smallest of the main
valley lakes and consists of a single shallow basin, with a maximum depth of 100
feet (34 meters). Kalamalka Lake contains two distinct basins separated by a
ridge in the unconsolidated material filling the structural trench (Map 9). The
most unusual feature of Kalamalka Lake is the presence of flat terraces of CaCO3
in the littoral zone that are found chiefly at the southern end of the lake.
These terraces are formed by the precipitation of CaCO3 during the summer from
the water of the epilimnion. The bottom of Okanagan Lake is characterized by
irregular undulations that presumably reflect glacial modifications in the
Valley from the last ice age. A large drumlinoid structure exists under 200
feet (61 meters) of water off Squally Point and a point 700 feet (213 meters)
deep was discovered south of Trepanier (Map 7). Skaha Lake is comprised of two
distinct basins that are separated by a bedrock sill at a depth of about 80 feet
(24 meters - Map 5). Osoyoos Lake is in fact three lakes with sand deposits
dividing them (Map 3). The northern-most of these "lakes" has three distinct
basins and attains a maximum depth in excess of 200 feet (61 meters). The
central and southern basins are not as deep, and are partially shielded from
significant input of terrigenous sediments by the northern-most basin.
Approximately 150 surface sediment and core samples from the Okanagan main
valley lakes were analyzed for particle size distribution. The mean particle
size analysis of the surface sediments of the main valley lakes are presented in
Table 4.2. The highest silt content was noted in Wood Lake, while the highest
clay content was observed in the deep water sediments of Okanagan Lake. The
sediment of Skaha and Osoyoos Lakes had very similar particle size
distributions. The terraces of Kalamalka Lake contained close to 16% sand and
57% silt.
TABLE 4.1
MINIMUM THICKNESS OF UNCONSOLIDATED MATERIAL UNDER
THE CENTERS OF THE MAIN VALLEY OKANAGAN LAKES
TABLE 4.2
SEDIMENT-SIZE DISTRIBUTION IN MAIN VALLEY OKANAGAN LAKES
Sedimentation rates for the main valley lakes were calculated by
pollen studies conducted by Anderson (1972). He concluded that ranching,
and other man-induced disturbances of the natural flora of the Okanagan
Valley dates back to around 1860 as large ranches were established to
supply beef and horses to miners attracted to the Caribou gold rush. His
pollen diagrams indicate a depletion of grass pollen in the near-surface
sediments of most lakes examined. For the purposes of this study, a
measure of 100 years is assumed for the basis of calculating man's
influence on the pollen distribution in cores from the valley lakes. The
mean annual sedimentation rate in each of the main valley lakes is
presented in Table 4.3.
TABLE 4.3
DEPTH TO MAN'S INFLUENCE AND NET ACCUMULATION RATE OF
SEDIMENT IN EACH OF THE OKANAGAN MAIN VALLEY LAKES1
1. St. John (1972)
2. Values for Osoyoos Lake based on a core taken in the south basin only.
Paleolimnological studies of the distribution of algal microfossils
(diatoms) were carried out on cores from all the main valley lakes except
Vaseux. Total counts of diatoms per microscope field correlated to
sediment depth are presented for Wood, Kalamalka, Okanagan and Osoyoos
Lakes in Figure 4.1.
Skaha Lake cores were analysed in a different manner and cannot be
directly compared with other lake data. However, spot checks using the
same techniques indicate a pattern of diatom abundance very similar to
that of Okanagan Lake:
The similarity of Skaha and Okanagan values might be expected due to
their close positions in the chain and the fact that Skaha Lake is rinsed
almost annually with Okanagan Lake water.
The entire artificially enriched period for Skaha Lake would only
involve the top 2-3 cm. of sediment, thus it is unlikely that any highly
revealing data would be presented in the limited comparisons made. The
generally lower values for diatoms in the upper sediments might be
indicative of a shift to a dominance of blue-green algae (indicators of
more eutrophic conditions) during July and August.
ABUNDANCE OF DIATOMS IN LAKE SEDIMENTS AS A FUNCTION
OF DEPTH FOR WOOD, KALAMALKA, OKANAGAN AND OSOYOOS LAKES.
Figure 4.1
The other lake values presented in Figure 4.1 reveals some interesting
trends. Kalamalka and Okanagan Lakes, despite considerable variation which is
probably due to annual in-lake differences, i.e. very dry year or very wet
year, vacillate around a fairly constant mid-point throughout the length of
core studied. Mean values of 4 per field and 24 per field for Okanagan and
Skaha Lakes respectively are not significantly altered throughout the core
length, an indication of little if any advancement toward a more eutrophic
state. Osoyoos Lake shows a gradual increase in diatom numbers over a long
period of time, indicating a generally steady advance toward eutrophy. Lower
numbers of diatoms near the surface could be indicative of a lake shift to the
blue-green algae dominance with more enriched conditions or a lack of compact-
ion in the near-surface sediments. The data from Wood Lake is most revealing
with regard to understanding its eutrophication. At a depth of 18-20 cm. the
lake rapidly increases in diatom production and then falls again, an indication
of a predominance of blue-green algae in recent years. This is an excellent
example of a lake turning eutrophic in a short period of time.
The mean concentrations of major elements found in the surficial sediments
of the main valley lakes are presented in Table 4.4. The more salient points
in this table are discussed below:
1) Wood Lake
Calcium content is closely associated with inorganic carbon content, due to
association as calcite. CaCO3 content is increased in the upper sediment
layer, probably due to increased carbon loading in more recent times and
the mineralization of this carbon to carbonate.
2) Kalamalka Lake
The dominant process in the sedimentary cycle of Kalamalka Lake is the pre-
cipitation of calcium carbonate. CaCO3 concentrations of 95% have been re-
corded in sediments from the terraces at the south end of the lake. The
terrace sediments represent the greatest concentration of this material
however, thus calcium content decreases with increasing depth.
3) Okanagan Lake
Calcium concentrations in Okanagan Lake sediments is strongly linked to in-
organic carbon content, probably linked as calcite. The importance of the
carbonate cycle in this lake is unknown.
4) Skaha Lake
Calcium in the sediments of Skaha Lake appear to be essentially unrelated
to inorganic carbon. This is at variance with the situation in Wood,
Kalamalka and Okanagan Lakes. Instead, calcium content appears to be
partitioned between silicon and phosphorus.
5) Osoyoos Lake
Variances of sodium, potassium and aluminum are largely accounted for by a
TABLE 4.4
MEAN CONCENTRATIONS OF MAJOR ELEMENTS IN SURFACE SEDIMENT
SAMPLES FROM OKANAGAN MAIN VALLEY LAKES
single variance vector, while the bulk of the calcium variance and part of
the aluminum variance is accounted for by an independent variance vector.
It seems probable that these distinctions reflect the mixing of at least
two silicate mineral populations.
The results of surface sediment analyses for carbon are presented in
Table 4.5. Percent inorganic, organic and total carbon is also presented
in Figure 4.2. The highest organic carbon contents occurred in Wood Lake
and the north arm of Okanagan Lake, (Table 4.5). The highest inorganic
carbon content occurs in the terraces of Kalamalka Lake which are primarily
composed of CaCO3.
On the basis of carbon content of sediments over time, some insight
into the trophic history of the main valley lakes can be gained (Figure
4.2). The lakes can be divided into three groups on the basis of carbon
content:
1) Osoyoos, Wood and Okanagan Lakes that have manifested a significant
increase in carbon accumulation over the past 100 years;
2) Skaha Lake that has registered a sharp increase in organic carbon
accumulation over the past 25 years, but little change before that;
3) Kalamalka Lake, that has shown an increase in CO3 accumulation over
the past 10 to 15 years.
From the above it is apparent that Osoyoos, Okanagan and Wood Lakes
have been subjected to some considerable increase in rate of change (as
indicated by carbon accumulation) over the same period of time as man's
development in an intensive agricultural community. In fact these lakes
drain the areas of most intense rural agricultural activity.
The lake most affected by urban development is Skaha Lake, by virtue
of being immediately downstream of the Penticton Sewage Treatment Plant.
It is likely that sewage discharge over the last 25 years has contributed
substantially to the rapid increase in sediment carbon accumulations. The
same parallel can be drawn between carbon accumulation in the Vernon Arm of
Okanagan Lake and sewage outfalls of the Vernon area. The unique carbonate
cycle of Kalamalka Lake has thus far effectively prevented any noticable
increase in organic carbon accumulation in the sediments.
The acid-soluble phosphorus content of the surface sediments has been
calculated for each of the main valley lakes (Table 4.6). These data have
made it possible to estimate the mean annual phosphorus accumulation to the
sediments. Statistical analysis and selective extraction on the sediments
from Skaha Lake suggest that hydroxyapitite (or related phases) may be
undergoing a rapid inorganic removal from the biologically available state
in this lake, thus limiting to a degree, the productive capacities.
TABLE 4.5
MEAN CARBON CONTENT OF SURFACE SEDIMENTS AND MEAN CARBON
ACCUMULATION RATES FOR OKANAGAN MAIN VALLEY LAKES
PROFILES OF CARBON CONTENT OF CORES FROM
THE OKANAGAN MAIN VALLEY LAKES. Figure 4.2
TABLE 4.6
ACID EXTRACTABLE INORGANIC PHOSPHORUS IN SEDIMENTS
FROM THE OKANAGAN MAIN VALLEY LAKES
Mercury content of the sediments of the Okanagan main valley lakes
have been determined. Surficial sediments of Wood Lake have the highest
mercury content (Figure 4.3). Most of this mercury occurs as a sulphide
and indications are that methylation, and hence its entry into the food
chain, is unlikely to occur. The mercury content of Kalamalka Lake is also
high, and presents a potential danger if it enters the food chain. The
mercury content in the sediments of roost of Okanagan, Skaha and Osoyoos
Lakes was considerably lower than values noted in Wood and Kalamalka Lakes.
In conclusion, the sedimentary evidence of long term (one century)
water quality degradation in Wood, Okanagan and Osoyoos Lakes - the lakes
draining the watersheds most affected by agricultural activity - suggests
that various agricultural practices have affected their water quality. In
addition to the carbon evidence, the surface distribution of mercury in the
Vernon Creek drainage, the Armstrong Arm of Okanagan Lake and in Osoyoos
Lake, provides strong circumstantial evidence that rural practices may have
resulted in the accumulation of this toxic element in the lake environment.
Skaha Lake appears to have undergone rather sudden changes in water
quality, contemporaneous with the initiation of sewage input from Penticton
some 25 years past. This resulted in an increased accumulation rate for
organic carbon. The carbonate cycle in Kalamalka Lake may have "protected"
this lake from significant water quality degradation since man settled in
the Okanagan Valley some 120 years ago.
PROFILE OF MERCURY CONTENT OF SEDIMENTS IN THE
OKANAGAN LAKES SYSTEM ALONG THE DEEPEST PART OF EACH LAKE.
MERCURY IN PARTS PER BILLION.
CHAPTER 5 Physical Characteristics of the Main
Valley Lakes.
5.1 PREVIOUS WORK
Clemens et al (1939) collected some basic physical data pertaining to
morphometry, temperature and Secchi disc transparency as parts of the
survey work they carried out. Stein and Coulthard (1971) also made some
limited physical measurements as a part of their more encompassing study.
Aside from the above general work, little was known of the physical
limnology of the Okanagan main valley lakes prior to the inception of the
Okanagan Basin Study.
5.2 RESULTS
Morphometric parameters for the six main valley lakes are summarised
in Table 5.1. The main valley lakes present a wide variety of basins,
with Okanagan Lake the largest in both volume and surface area and Vaseux
Lake the smallest. Kalamalka Lake is the second largest lake, while Wood,
Skaha and Osoyoos Lakes are of more similar size and volume. The greatest
maximum depth occurs in Okanagan and Kalamalka Lakes, 794 and 466 feet
(242 and 142 meters) respectively, while the remainder of the lakes have
maximum depths of about 169 feet (50 meters). The mean depth of the lakes
range from 250 feet (76 meters) for Okanagan Lake, to 21 feet (6.5 meters)
for Vaseux Lake (Table 5.1). The theoretical water replacement time
(residence time) of the lakes varies from 65 years for Kalamalka Lake to
1.5 weeks for Vaseux Lake (Table 5.2).
The temporal changes in selected thermal layers (epilimnion,
mesolimnion and hypolimnion), have been calculated for the main valley
Okanagan lakes (Figures 5.1 and 5.2). From these observations, the lakes
of the mainstem were classified as dimictic; that is, two circulation
periods per year. Temperature data from moored thermographs in each lake
indicated that the lakes reached their maximum temperature in 1971 between
the end of July and the middle of August (Table 5.3). The time of maximum
lake temperature occurred at the approximate time of the highest air
temperatures recorded at Penticton. The rate of warming of the hypo-
limnions of the five main lakes were as follows:
Osoyoos 0.54 °C/month Skaha 0.37 Wood 0.26 Kalamalka 0.18 Okanagan 0.06
Wood Lake, for its size and mean depth should have had the highest rate of
hypolimnetic warming. These data strongly support the theory that cold
groundwater
TABLE 5.1
MORPHOMETRY OF THE SIX MAIN VALLEY LAKES IN THE OKANAGAN BASIN
(Blanton and Ng, 1972)
1. Osoyoos (N) is the basin north of the highway bridge. Osoyoos (S) is the
basin between the highway bridge and the U.S. border
2. Data compiled from charts of the Fish and Wildlife Branch,
Department of Recreation and Conservation, B.C.
3. Data compiled from a chart by A.M. Thomson, Study Director
4. These data were obtained from maps of the Canadian National Topographic
System, 1960. Scale 1:126,720.
TABLE 5.2
MEAN ANNUAL OUTFLOW AND THEORETICAL WATER REPLACEMENT TIME
(RESIDENCE TIME), OKANAGAN MAIN VALLEY LAKES
VOLUMES ASSOCIATED WITH GIVEN TEMPERATURE RANGES
OBSERVED DURING THE 1971 MONITOR CRUISES IN OSOYOOS,
SKAHA AND OKANAGAN LAKES. Figure 5.1
KALAMALKA LAKE
1971
VOLUMES ASSOCIATED WITH GIVEN TEMPERATURE RANGES
OBSERVED DURING THE 1971 MONITOR CRUISES IN WOOD AND
KALAMALKA LAKES. Figure 5.2
TABLE 5.3
PERIOD OF MAXIMUM SURFACE TEMPERATURES FOR EACH LAKE
WHERE MOORED THERMOGRAPHS MERE LOCATED
TABLE 5.4
SUMMER HEAT INCOMES FOR THE MAIN VALLEY LAKES IN 1971
inflow plays an important role in the limnology and hydrologic cycle of
this lake.
The heat content in g cal/cm2 was computed for each lake from 1971
cruise temperature data. These data were used to compute the summer heat
income. Okanagan Lake had the highest heat income of the five main valley
lakes (excluding Vaseux) and Wood Lake had the lowest (Table 5.4). Two
values for heat content were computed for Vaseux Lake from limited data,
since it was not sampled as intensively as the other lakes. It appears that
it has the lowest heat content of the main valley lakes because it is the
smallest.
Secchi disc and light transmittance data were gathered during the
monitor cruise program in 1971. The lakes are listed in Table 5.5, in order
of increasing transparency. The tendency of increased transmission in the
blue light range is characteristic of dear and unproductive water masses
(Sverdup, Johnson and Fleming, 1942). If one compares the ratio of blue to
green transmission value, the ratio is lowest for Mood Lake and highest for
Kalamalka Lake.
water transparency as determined by measurements of the Secchi disc
produced results similar to the transmission data with Okanagan and
Kalamalka Lakes being the clearest (highest mean Secchi reading) while Wood
and Osoyoos Lakes were the least transparent (Table 5.5). These data, when
compared with past records, indicate no significant decrease in transparency
from measurements taken over the past five years (South Okanagan Health
Unit, unpublished data and B.C. Fish and Wildlife Branch, unpublished data)
in Okanagan, Wood and Kalamalka Lakes. However, Skaha and Osoyoos Lakes have
shown some diminishment of water transparency during this period.
The study tracking Okanagan River water as it entered Skaha Lake
consisted of four experiments; two in the spring of 1971 during homogeneous
lake conditions and two in the fall when Skaha Lake was highly stratified
with a strong thermo-cline at about 10 meters. General details of the
experimental series are provided in Table 5.6.
During the spring experiments, it was noted that dye generally mixed
homogeneously throughout the water mass, although detailed vertical sampling
series were not taken. A synoptic series for dye distribution during the
spring experiments is presented in Figure 5.3. It is noted that the dye
(and presumably the Okanagan River outfall) moves quickly to the northwest
corner of the lake and from there tends to diffuse in a generally south
direction, over time. Tracking drogues set at 1, 2 and 3 meters during the
spring experiments moved southwest, generally consistent with the dye
movements.
During the fall experiments, modifications were made to allow vertical
sampling to 20 meters. Sampling showed no dye below the thermocline,
indicating no
TABLE 5.5
TRANSMISSION METER VALUES FOR FIVE MAIN VALLEY LAKES*
TABLE 5.6 GENERAL DETAILS OF THE SKAHA LAKE
DIFFUSION EXPERIMENTS
SYNOPTIC MAPS OF DYE DISTRIBUTION FOR SKAHA LAKE
3-6 APRIL, 1971. Figure 5.3
mixing of river and hypolimnetic waters. Horizontal dye movements in the fall
were essentially identical for those during the spring (Figure 5.3).
Southerly winds tended to slow the spreading of the dye, while northerly winds
tended to hasten it.
The general horizontal fate of the Okanagan River plume is schematically
presented in Figure 5.4. This basic movement consists of a main flow directed
to the northwest corner of the lake by the small dyke at the river mouth.
This is followed by a well-defined southerly current along the west shore.
Complete mixing is assumed during homothermic conditions. During summer
stratification, the river plume mixes only with the epilimnion.
More detailed results of the physical limnology studies on the main
valley lakes are included in Appendix D.
CHAPTER 6 Chemical Characteristics of the Main
Valley Lakes. 6.1 PREVIOUS WORK
In 1936, Rawson collected surface water samples of Okanagan Lake for
chemical analyses (Clemens et al 1939). Measurement of oxygen concentrations
and pH in Okanagan, Kalamalka and Wood Lakes were taken in July and August
1935 as part of Rawson's survey. Coulthard and Stein (1968, 1969), Stein and
Coulthard (1971) and Booth collected numerous samples for chemical analyses
from all major lakes, including one of the first measurements of phosphorus
concentrations. Clarke and Alcock (1968) measured nutrient input to some
Okanagan Valley lakes to construct a preliminary nutrient budget based
chiefly on sewage plant effluent.
6.2 RESULTS
6.2.1 Dissolved Oxygen
Hutchinson (1957) indicated probably more can be determined about the
nature of a lake from a series of oxygen determinations than from any other
kind of chemical data. These important data for spring, summer and fall are
presented in Table 6.1. Epilimnetic oxygen concentrations remained near
saturation levels in all lakes throughout the summer months. Dissolved
oxygen in the hypolimnia of Osoyoos, Wood and Skaha Lakes was well below
saturation for much of the summer. The hypolimnia of Kalamalka and Okanagan
lakes remained well oxygenated.
Calculation of the rate of oxygen depletion of hypolimnetic water during
the summer stratification provided an estimate of annual biological
production. These data (Table 6.2) indicate Skaha Lake had the most rapid
depletion rate, followed by Wood and Osoyoos Lakes. No attempt was made for
computing areal depletion rates for Okanagan and Kalamalka Lakes since they
are subject to limitations for such calculations imposed by Hutchinson
(1957); i.e., maximum depths greater than 75 meters. Based on the trophic
index of Dobson (1972) where mesotrophy equals 1.0, both Skaha and Wood Lakes
are on the eutrophic side of the scale from a consideration of oxygen
depletion rate. There has been little change in hypolimnetic dissolved
oxygen concentration of Okanagan Lake since Rawson's measurements taken in
1935; however, Skaha Lake has exhibited an increase in it's hypolimnetic
oxygen deficit over the past 25 years. Ferguson (1949) in July 1948, noted
values of 10.35 mg/l or 85% saturation, while the current survey noted 8.55
mg/l or 70% saturation. The oxygen content of the hypolimnetic water of Wood
Lake has not changed appreciably from the values noted by Rawson in 1936.
TABLE 6.1
CONCENTRATIONS OF DISSOLVED OXYGEN IN THE OKANAGAN MAIN VALLEY LAKES.
EXPRESSED IN PARTS PER MILLION
(PERCENT SATURATION IN BRACKETS)
TABLE 6.2
DAILY OXYGEN DEPLETION RATES, AREAL DEPLETION RATES AND TROPHIC INDICES
FOR THE OKANAGAN MAIN VALLEY LAKES
TABLE 6.3
AVERAGE CONCENTRATIONS OF NITROGEN. PHOSPHORUS AND CHLOROPYLL-
a IN THE OKANAGAN MAIN VALLEY LAKES*
(EXPRESSED IN MICROGRAMS PER LITER)
On the basis of oxygen data, the lakes of the main valley system
can be ranked as follows:
1. Skaha Eutrophic
2. Wood Eutrophic
3. Osoyoos Mesotrophic
4. Okanagan Oligotrophic
5. Kalamalka Extremely Oligotrophic
6.2.2 Nutrients
The main valley lakes exhibited considerable seasonal and valley-wide
variation in nutrient content. A representation of these data from a
variety of sources are presented in Table 6.3. These data indicated
general conditions. The data collected during the study is presented in
Appendix C. These data were not presented in a concentrated form in the
text since any condensation would result in losing some of the trends
within lakes and/or time periods. The following discussions then refer to
data in Appendix C.
(a) Wood Lake
Wood Lake had the highest observed concentrations of NO3(N) and PO4(P)
of the five main valley lakes sampled during spring turnover - 20 ug/1 and
80 ug/1 respectively. Epilimnetic concentrations decreased throughout the
summer, reaching the lower range of sensitivity of the analytical method
used, by midsummer. The large NO3(N) and PO4(P) decrease with time, relates
inversely to chlorophyll-a concentrations which increased from 9 to 100
ug/1 between April and June. Decrease in surface silica concentrations is
likely linked to diatom periphyton dominance, (Gonophonema ventricosums
and Synedra sp.), which accounted for 60 to 80% of the total numbers.
(Chapter 7.3).
Depletion of epilimnetic nutrients was accompanied by increased PO4(P)
and NO3(N) in the hypolimnion. PO4 content of the sediments of Wood Lake
was also comparatively high.
The depletion of NO3(N) in the hypolimnion toward the end of summer
stratification was likely due to its reduction to NH3 or N2. The
considerably lower concentrations of NO3(N) as compared to PO4(P) would
indicate that NO3(N) is probably presently the limiting nutrient in
phytoplankton growth in this lake.
(b) Skaha Lake
Mean concentrations of NO3(N) and PO4(P) at spring turnover were 10
ug/1 and 16 ug/1 respectively. Low epilimnetic NO3(N) concentrations
throughout the summer tend to indicate this is the factor limiting
phytoplankton production. The extremely high PO4(P) values in surface
waters in June are attributed to surface runoff.
Horizontal PO4(P) distribution showed a general north-to-south decrease
in concentration throughout the sampling period, indicating that the main
nutrient source was the Okanagan River. Station 1 on the east side of the
lake (not directly influenced by the river plume - Section 5.2), showed the
lowest phosphate concentration of the entire lake surface.
The rapid decrease of epilimnetic PO4(P) from 51 to 0.005 ug/l between
August and October correlates well with an increase in chlorophyll-a
concentrations from 20 to 214 ug/l and a bloom of anabaena flos-aquae. The
depletion of epilimnetic PO4(P) and NO3(N) also correlates with their
increase in the hypolimnion during the August to October period.
(c) Osoyoos Lake
In the north basin, epilimnetic PO4(P) levels were about 13 ug/1 from
April to June, but had increased to 213 ug/1 by August. The general north-
to-south decrease in concentration indicates the Okanagan River as the
probable major source. The sharp decrease by October was probably due to an
algal bloom, although no chlorophyll-a. data is available for October to
corroborate this.
The central and southern basins developed only weak thermal
stratification throughout the summer, thus nutrient concentrations were
generally similar throughout the entire water column. These two basins
showed similar nutrient concentrations and seasonal patterns to those of the
north basin epilimnion, except that no peak PO4(P) concentration was observed
in the south basin in August.
The weak thermal stability observed has two important effects: First,
the absence of a thermocline means that any organic matter produced on the
surface falls freely to the bottom of the lake. Second, no thermocline means
greater warming of the bottom waters, which results in an increased rate of
oxidation of organic material.
(d) Okanagan and Kalamalka Lakes
The fact that the nutrient values over most of the lakes' surface were
so low PO4(P) values in the epilimnion and hypolimnion of both lakes falling
below the detection level of the analytical method employed), attests to the
Oligotrophic nature of both these bodies of water. Both lakes exhibited well
defined orthograde oxygen curves with relatively poorer oxygen conditions
being observed only in the Armstrong arm of Okanagan Lake. In Kalamalka, the
analysis for chlorophyll-a. content showed a seasonal average of only 2.5
ug/l and only in the Armstrong and Vernon arms of Okanagan Lake did the
values get above 15 ug/l with the main body of this lake averaging 5.0 ug/l
Both lakes exhibited peak concentrations of PO4(P) in June with the 1m
values in Kalamalka Lake averaging 90 ug/l and the 1m values in Okanagan
Lake averaging
260 g/l in the north and 70 g/l in the south. It is interesting to note
that during this period, the Vernon Arm of Okanagan Lake had a surface
concentration of PO4(P) of 10 ug/l (the lowest on the lake's surface). While
there was a three-fold increase in surface chlorophyll-a from 6 to 18 ug/l,
this alone could not account for such a low value. It is quite probable that
the main portion of the nutrient input from Vernon Creek (which is noted as a
major source of PO4(P) input into the lake), was taken up by the aquatic
macrophytic vegetation that showed a tremendous increase at this time. The
high PO4(P) concentrations off Lambly (Bear) Creek (690 ug/l) indicate this
as a rich source of nutrient input into the lake during spring runoff.
NO3(N) concentrations in the epilimnia of both lakes decreased from a mean of
22 ug/l in the spring to below detection level. Concentrations in the
hypolimnia increased to a mean value of 30 ug/l.
(e) Discussion
On the basis of nutrient availability, the lakes would have to be ranked in
order of decreasing fertility:
1. Wood 2. Skaha 3. Osoyoos 4. Okanagan 5. Kalamalka.
The point of interest from the present study which should be emphasized, is
that a11 the lakes (with the exception of Wood Lake) received "spike" inputs
of PO4(P) which have been attributed to runoff, at some time during the
seasonal cycle. This puts increasing importance on the value of NO3(N) or
some other factor such as trace metals in having a limiting influence on
algal growth. This (1971) was an atypical year for meteorological conditions,
and time and amount of surface spring runoff, so that it might prove
difficult to extrapolate the findings of the present study with any
conclusiveness to those of previous or subsequent years.
6.2.3 Major Ions
The relative abundance of major ions is a reflection of natural aquatic
chemical processes modified by regional geochemistry. The distribution
within a given lake or among lakes is a result of biological activity,
surface runoff, groundwater, precipitation and most importantly, the internal
factor of sediment-water interaction.
Concentrations of major ions in the main valley lakes varied from lake
to lake, but showed little seasonal variation (Table 6.4). An anion-cation
balance sheet for all lakes appears in Table 6.4. The relative abundance of
major ions within a particular lake was similar to the curve for the average
of the world's freshwater, with HCO3 >Ca >Na >Mg >SO4 >F, on a molar basis.
When compared with other major lake districts, the concentration of
major ions in the lakes of the Okanagan drainage basin are quite high, an
order of magnitude higher than lakes on the Canadian Shield (Armstrong
and Schindler, 1971), and higher than the world average for freshwater
(Livingstone, 1963). These high concentrations are the result of an array
of soluble geological materials in the watershed, including limestones,
glacial drift, clay-silt terraces, and conglomerate rock or basaltic
areas.
TABLE 6.4
AVERAGE SEASONAL CONCENTRATION AND LAKE AVERAGE OF MAJOR
ANIONS/CATIONS IN OKANAGAN MAIN VALLEY LAKES
CHAPTER 7 Biological Characteristics of the Main
Valley Lakes. 7.1 NUTRIENT BIOASSAY
The nutrient bioassay program involved a number of different approaches.
Nutrient enrichment bioassay, pure culture bioassay, sewage enrichment and
trace metal enrichment studies were all a part of the program. In this
section, the results of each aspect are reported independently and an attempt
to link them meaningfully is made at the conclusion.
It should be noted that the nutrient bioassay program went through an
ongoing developmental process, thus the experiments of 1970 were of a "survey
nature" in an effort, primarily, to define the problems and develop adequate
techniques. To this end, methodology both in the field and laboratory, varied
in the two years of the study. Only the data of the 1971 portion of the pro-
gram is presented here to avoid duplication and confusion. Results of 1970
and 1971 showed general agreement within bounds expected when one considers
the developmental nature of the 1970 program. Trends from both years
experiments were very similar and it is in that context that the 1970 results
are discussed.
7.1.1 Nutrient Enrichment Bioassay
(a) Osoyoos Lake
Phytoplankton growth in this lake was stimulated by addition of a small
amount of phosphorus (0.09 mg/l), as PO4(P) and increasing nitrogen
concentration from 0.90 to 30.5 mg/l (NO3(N)). Growth tended to be
proportional to amount of nitrogen added, although increasing phosphorus
alone or with low NO3, alone there was no notable stimulation. The highest
growth rate was achieved (Figure 7.1), when 9.3 mg/l of NO3(N) and 0.28 mg/l
of PO4(P) were added. Increasing CO2 concentrations also increased the growth
rate with the greatest yield at 44 mg/l CO2.
(b) Vaseux Lake
Additions of NO3(N) alone at both concentrations produced algal growth
slightly greater than observed in the control (Figure 7.1). PO4(P) when added
alone promoted more growth than NO3(N) alone, with a yield about twice that
noted in the control. NO3(N) and PO4(P) added together at the lowest
concentrations had little stimulatory effect, but at the highest
concentrations, growth was about ten times that of the control (Figure 7.1).
(c) Skaha Lake
Water samples from one station (mouth of Okanagan River) in 1970, and two
stations (mouth of Okanagan River and near Okanagan Falls), in 1971 were used
RESULTS OF THE NUTRIENT ENRICHMENT BIOASSAY EXPERIMENTS,
OKANAGAN MAIN VALLEY LAKES, 1971. Figure 7.1
in the nutrient enrichment bioassay. Results from 1970 and 1971 at
Station 1 showed similar results, so only the 1971 data are discussed
here.
In the Station 1, (Okanagan River mouth) sample, additions of NO3(N) at
three concentrations - 0.9, 3.1, and 9.3 mg/l - were stimulatory, while a
single PO4(P) addition was not (Figure 7.1). Additions of NO3(N) and PO4(P)
together at low concentrations had little effect, but at higher
concentrations stimulated growth to about three times that of the control
(Figure 7.1).
Samples from Okanagan Falls (Station 2) grew up to four times as
quickly as the control when NO3(N) at either of the two concentrations was
added (Figure 7.1). Addition of PO4(P) did not stimulate growth.
(d) Okanagan Lake
Two nutrient enrichment bioassays were performed in 1970 on water
samples taken from one station; mid-lake off Summerland Trout Hatchery.
Results of both bioassays in 1970 showed similar trends and are therefore
discussed as a single experiment.
Additions of NO3(N) and PO4(P) alone had no stimulatory effect on the
growth of algae in test samples. Flasks given constant amounts of PO4(P)
but varying amount of NO3(N), showed an increase of algal growth with an
increase in the amount of nitrogen added. When concentrations of NO3(N)
were held constant and the amounts of PO4(P) varied, growth remained
constant throughout the series. Bicarbonate additions produced results
similar to those discussed for Osoyoos Lake.
Six stations were selected for the nutrient enrichment bioassay
experiment in 1971. In samples from Station 1; Vernon Arm, additions of
NO3(N) and PO4(P) alone at two concentrations had little effect on the
growth of algae. Nutrient additions of NO3(N) and PO4(P) together in lowest
concentrations promoted growth to three times that of the controls, whereas
NO3(N) and PO4(P) together at the highest concentrations stimulated growth
to approximately fifteen times that of the controls (Figure 7.1).
Addition of NO3(N) in the lowest concentrations to the Station 2,
Armstrong Arm sample had no effect on the growth of test samples, whereas
the addition of NO3(N) at the highest concentration stimulated growth beyond
that of the highest concentration of NO3(N) and PO4(P) together. The growth
with NO3(N) alone was equivalent to ten times that of the controls (Figure
7.1). Addition of PO4(P) alone and NO3(N) and PO4(P) together at both
concentrations, stimulated growth to only two times that of the controls
(Figure 7.1).
In the Station 3, Kelowna Bridge samples, NO3(N) and PO4(P) additions
by themselves, growth of algae was in most cases below that of the
controls.
NO3(N) and PO4(P) additions together at the lowest concentrations, stimulated
growth to about twice that of the controls; while with additions at the
highest concentrations, growth was greater than five times the controls
(Figure 7.1).
Station 4 (off Peachland) sample, flasks with NO3(N) and PO4(P) additions
alone at both concentrations showed less growth than seen in the controls.
Flasks with NO3(N) and PO4(P) additions together at both concentrations,
stimulated growth to from ten to fifteen times that of the control flasks
(Figure 7.1).
Growth inhibition was observed with additions of NO3(N) at both concentra-
tions to Station 5 samples, whereas stimulation of growth to a little beyond
that of the control was evident with PO4(P) additions alone. Additions of
nitrogen and phosphorus together at both concentrations promoted growth of
algae to three and ten times that of the control flasks (Figure 7.1).
In samples from Station 6 (off Penticton), only a little growth beyond
that observed in the controls was evinced when NO3(N) and PO4(P) were added
alone. Additions of NO3(N) and PO4(P) together in the lowest and highest
concentrations, showed similar trends to the other stations tested; namely,
stimulation up to two and ten times respectively, the growth of the control
flasks (Figure 7.1).
(e) Kalamalka Lake
Two nutrient enrichment experiments were performed on water samples taken
from one mid-lake station; off Crystal Waters Resort in 1970. Both sets of
experiments showed similar trends, thus are treated as one for discussion.
Addition of NO3(N) and PO4(P) alone, as well as with the addition of a constant
amount of NO3(N) and varying amounts of PO4(P) together, showed essentially the
same growth as seen in the controls. When PO4(P) additions were kept constant
but NO3(N) varied, growth was up to three times greater than the controls.
Two stations were selected for the nutrient enrichment water sample
sources in 1971. Station 1, located in the southern region, showed inhibition
when NO3(N) was added alone, and only slight growth with PO4(P) alone (Figure
7.1). Similarly, when NO3(N) and PO4(P) were added together at the lowest
concentration,
growth was only slightly more than that of the controls, whereas NO3(N) and
PO4(P) added together at the highest concentration promoted growth to twelve
times that of the controls (Figure 7.1).
The other station, located in the northern region, showed growth of algae
three times higher than the controls when NO3(N) was added alone, while the
addition of PO4(P) at both concentrations had little effect on growth (Figure
7.1). At the lowest concentration of NO3(N) and PO4(P) together, growth was
promoted to six times that of the controls, but at the highest concentration
it was stimulated to twenty-five times the controls (Figure 7.1).
(f) Wood Lake
Two stations were used in Wood Lake. Station 1 located in the northern
region showed a growth of algae twice that of the controls with NO3(N) additions
(Figure 7.1). At the lowest concentration of PO4(P), no growth was observed
beyond that of the controls, whereas growth doubled at the higher concentration
of PO4(P). In both cases, with the addition of nitrogen and phosphorus together,
growth was only twice the controls, a phenomenon quite different from that
observed in the other Okanagan Lakes.
Station 2, located in the southern region of the lake, showed stimulation
of growth twice that of the controls with additions of both concentrations of
NO3(N), whereas additions of PO4(P) only stimulated growth slightly above the
controls (Figure 7.1). Addition of NO3(N) and PO4(P) together at the lowest
concentration, showed stimulation of growth similar to the addition of PO4(P)
alone, whereas at the highest concentration of NO3(N) and PO4(P), growth was
promoted to three times that of the controls (Figure 7.1).
7.1.2 Pure Culture Bioassay
Three test organisms were used in the experiments; Selenastrum capricornutum,
Anabaena flos-aquae and Microcystis aeruginosa. These species were used because
they represented a good cross-section of the various types of algae likely to be
found in lakes of different nutritional status. Selenastrum is a unicellular or
loosely aggregated colonial green alga (Chlorophyceae), and the two remaining
species are blue-green algae (Chlorophyceae). Anabaena is a filamentous species
that is capable of fixing nitrogen. Microcystis is either unicellular or loosely
aggregated colonial and cannot fix nitrogen. As far as is known, only Anabaena
occurs commonly in lakes of the Okanagan Basin. Some Microcystis, has been noted,
but its specific identity is uncertain. To our knowledge, Selenastrum does not
occur in the main valley lakes. Intra and inter lake comparisons are made on the
basis of yield of maximum growth as measured by total radioactive counts per
minute (TCPM). Chlorophyll-a. determinations were also made in 1971, but the
sample size was small (35 ml.) and results so variable they could not be used.
(a) Osoyoos Lake
Results of a single pure culture bioassay conducted in 1970 on mid-lake
water near the city of Osoyoos, produced the highest yield of Anabaena of any of
the five lakes tested. Growth of Microcystis, and Selenastrum was relatively low.
Available nutrients at the time of the test run were 0.01 mg/l for both NO3(N) and
PO4(P) respectively. The excellent response of Anabaena in Osoyoos Lake at this
time may be related to its ability to fix nitrogen in the presence of
insufficient external supply. In 1971 the pure culture bioassay was repeated
using three stations (Figure 7.2). Growth of Anabaena and Microcystis was high at
Station 2, but relatively low at Stations 1 and 3. Selenastrum showed moderate
growth at all stations with little variability in growth among stations. Anabaena
exhibited comparatively low growth but was most abundant in the mid-basin sample,
as was the case with Microcystis.
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM THREE OSOYOOS
LAKE STATIONS.(1971) Figure 7.2
(b) Vaseux Lake
A single pure culture bioassay experiment was performed in 1971 using
surface water obtained from a mid-lake station (Figure 7.3). Growth of all
three species was very similar to that generally observed in Osoyoos Lake
waters.
(c) Skaha Lake
In 1970, two pure culture bioassay experiments were performed with
samples from each of two stations. The greatest yield of Selenastrum was
obtained in the first test station just off the mouth of the Okanagan River.
Growth of the other test algae was low at both stations. Chemical analysis of
the water showed nutrient concentrations of 0.01 NO3(N) and 0.01 PO4(P) mg/l,
which substantiates, to some degree, the results obtained in the bioassay.
Despite the apparent low nutrient concentrations, there was obviously
sufficient nutrients to support the observed heavy growth of Selenastrum noted
at this station. In the second test, a high yield of all three algae was
observed at Station 1, just off the mouth of the Okanagan River. Growth of
the test algae at Station 2 off Okanagan Falls was good, but not exceptional.
Available nutrients at Station 1 were very high at the time of this test; 0.11
NO3(N) and 0.16 PO4(P) mg/liter, while at Station 2, concentrations of NO3(N)
and PO4(P) were 0.01 and 0.01 mg/ liter respectively. The observed algal
yield at each of the stations is in agreement with the noted nutrient levels.
In the 1971 pure-culture bioassay, water from four stations was tested.
The results are presented graphically in Figure 7.4. Stations 1, 2 and 3
were similar in yield with Anabaena growing best at Station 3, and
Selenastrum at Station 2. Station 2 at the mouth of the Okanagan River,
tended to promote the highest algal growth, further substantiating results
obtained in the 1970 experiment, and indicating considerable nutrient
availability at this station located in the plume of the Okanagan River.
(d) Okanagan Lake
In 1970, two pure culture bioassay experiments were conducted on water
obtained from three stations: Vernon Arm, Kelowna Bridge and off Summerland
Trout Hatchery. In the first experiment, water from the Vernon Arm
and off Summerland Hatchery promoted good growth of all test algae. Results
of chemical analyses of water from these stations showed low nutrient levels
at all stations; 0.01 mg/liter NO3(N) and PO4(P), with the exception of 0.08
mg/liter NO3(N) at the Kelowna Bridge Station. The high rankings of algal
growth at these Okanagan Lake stations does not correlate well with the
chemical analyses, but this is not surprising when one considers the
sensitivity levels of these nutrient determinations.
Results of the second experiment conducted in August were very
similar to results of the first test, with water in the Vernon Arm and off
Summerland
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM ONE VASEUX
LAKE STATION. (1971) Figure 7.3
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM FOUR SKAHA
LAKE STATIONS. (1971) Figure 7.4
Hatchery exhibiting higher yields than water off the Kelowna Bridge. Nutrients
were again at low levels; 0.01 mg/liter, but total P values were high in the
Vernon Arm; 0.08 mg/liter.
In 1971, one pure culture bioassay experiment was performed on water samples
from 10 stations. The data presented in Figure 7.5 and 7.6 indicate there was
little variability in growth among stations, and a very low growth of all test
algae. Among the six lakes tested in 1971, Okanagan Lake ranked lowest in yield.
(e) Kalamalka Lake
A surface water sample from mid-lake served as the medium for two pure culture
bioassay experiments conducted in 1970. In the first run, Anabaena and Microcystis
exhibited moderate growth, while the growth of Selenastrum among the lowest re-
corded in any lake. In the second test, results were similar to those just
described. Available nutrients were low at both periods; 0.03 mg/liter in NO3(N) and
0.01 mg/liter in PO4(P) in the first experiment; and 0.01 mg/liter for both
nutrients in the second experiment. In 1971, five stations in Kalamalka Lake were
tested (Figure 7.7). There was little difference in yield among stations for the
alga Selenastrum and next to Okanagan Lake, its yield was one of the lowest
recorded. Growth of Anabaena and Microcystis was moderate, ranking fourth among six
lakes tested in 1971 (Figure 7.7).
(f) Wood Lake
In 1970, only one pure culture bioassay experiment was performed on a surface
sample from mid-lake. Yield of Microcystis was the highest recorded in any of the
five lakes tested, and very similar to the algal yield obtained in Okanagan Lake
off Summerland hatchery. Growth of Anabaena was high. Growth of Selenastrum was the
lowest observed in any lake. Chemical analysis showed low nutrient availability;
0.01 mg/liter for both NO3(N) and PO4(P). In 1971, water from three stations was
tested (Figure 7.8). and the yield of Selenastrum was second only to Skaha Lake.
Growth of the other species was moderate, but not exceptional. There was little
difference in yield among the three stations tested. At the time of the 1971 sam-
pling, Wood Lake was between blooms and available nutrients low.
7.1.3 Sewage Enrichment Experiments
Since a chief source of PO4(P) in the basin lakes is municipal sewage, a series
of experiments were designed to demonstrate the fertilizing capacity of both raw
and treated sewage when added to the uncontaminated lake water. It was also
interesting to note the short term response of phytoplankton and the shift of
dominant species in the algal assemblage. Results from the five lakes tested were
similar with respect to growth, but different in absolute yield and final species
succession. These differences are not surprising since the standing stock of
phytoplankton in each lake differed at the time of sampling.
It is noted that these laboratory experiments were not designed to duplicate
the actual lake situation and certain differences did exist. For example, the
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM
FOUR NORTH OKANAGAN LAKE STATIONS. (1971) Figure 7.5
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM SIX
SOUTH OKANAGAN LAKE STATIONS.(1971) Figure 7.6
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM FIVE
KALAMALKA LAKE STATIONS. (1971) Figure 7.7
RESULTS OF PURE CULTURE BIOASSAY EXPERIMENTS FROM THREE
WOOD LAKE STATIONS. (1971) Figure 7.8
flasks were shaken regularly and there was no stratification or settling in the
flasks, thus the nutrients were constantly available to algae. This is not
necessarily the case in the lake where several physical forces may separate
nutrients and algae. These experiments were intended to be informative examples
rather than definitive extrapolations to the natural situation.
The general effects of the sewage enrichment experiments on the phytoplankton
of each lake are discussed below.
(a) Osoyoos Lake (Figure 7.9)
The control flasks, after nine days incubation, contained a mixture of the
blue-green alga Lyngbya sp. and the diatom Fragilaria crotonesis. With the
addition of raw sewage, the succession changed to green algal dominance;
Chlorella spp. with the remainder being several genera of diatoms. With primary
treated sewage addition, the succession changed to diatom dominance, chiefly
Navicula sp., Nitzschia sp., and Fragilaria spp. The addition of mixed liquor to
flasks produced results similar to that of primary treated sewage except the
production of algae was much greater. Addition of secondary, non-chlorinated
sewage showed similar trends and species composition to the above, but algal
production was reduced. The addition of final chlorinated effluent led to a
mixture dominated by the diatom Fragilaria crotonesis , and the green alga
Scenedesmus sp. Tertiary treated sewage additions gave way to a final succession
of almost exclusively Scenedesmus sp.
(b) Skaha Lake (Figure 7.10)
The controls after nine days contained almost exclusively the diatoms
Fragilaria crotonesis , Asterionella formosa, and Tabellaria fenstrata, and the
blue-green Anabaena sp. The flasks receiving raw sewage after nine days
contained considerably more Anabaena sp., with Fragilaria crotonesis and Synedra
sp. being the dominant diatoms. Additions of primary treated sewage showed
similar results to that of the flasks with raw sewage additions, except that
Anabaena sp. was more abundant, 60%. Mixed liquor additions decreased the amount
of Anabaena sp. and Fragilaria crotonesis , but stimulated the growth of
Navicula sp. Flasks receiving secondary non-chlorinated and final chlorinated
sewage, had an increased growth of Anabaena sp. of 50% and 75% respectively.
Flasks with tertiary treated sewage additions contained a heavy growth of
Anabaena sp. with some Fragilaria crotonesis still present.
(c) Okanagan Lake (Figure 7.11)
The control flasks after nine days growth contained mostly the diatoms
Asterionella formosa and Synedra sp. With the addition of raw sewage, species
composition changed from diatoms to that of green algal dominance, Shorella sp.
and Scenedesmus sp. With the addition of primary treated sewage, Scenedesmus sp.
became the dominant alga, but with some Navicula sp. present. With the
BIOASSAY RESULTS, SEWAGE ENRICHMENT EXPERIMENTS AFTER NINE
DAYS GROWTH ON OSOYOOS LAKE WATER, 1971. Figure 7.9
BIOASSAY RESULTS, SEWAGE ENRICHMENT EXPERIMENTS AFTER NINE
DAYS GROWTH ON SKAHA LAKE WATER, 1971. Figure 7.10
BIOASSAY RESULTS, SEWAGE ENRICHMENT EXPERIMENTS AFTER NINE
DAYS GROWTH ON OKANAGAN LAKE WATER, 1971. Figure 7.11
addition of mixed liquor, Navicula sp. became dominant (90%). Secondary non-
chlorinated sewage additions promoted the dominance of Navicula sp. again, but to
a lesser degree than that of mixed liquor additions. A slight increase in the
yield of the green alga Scenedesmus sp. was also noted in flasks with secondary
non-chlorinated sewage additions. Enrichment of flasks with final chlorinated and
tertiary treated sewage led to a green algal dominance, mainly Scenedesmus sp.
and Chlorine sp., with some Navicula sp. present.
(d) Kalamalka Lake (Figure 7.12)
The controls after nine days contained almost exclusively diatoms, chiefly
Synedra spp. and Navicula spp. Flasks receiving raw sewage promoted a complete
species shift to that of green algal dominance, mainly Scenedesmus sp. and
Chlorine sp. Primary treated sewage additions gave similar results to that of raw
sewage additions, but with less algal growth. With the addition of mixed liquor
and secondary non-chlorinated sewage, the diatoms remained dominant, chiefly
Navicula spp. but with some Scenedesmus sp. present. Flasks with final
chlorinated and tertiary treated sewage showed a diatom dominance again, but this
time consisting of Synedra sp. in final chlorinated sewage, and Synedra sp.
again, along with Fragilaria crotonesis, in flasks with primary treated sewage.
(e) Wood Lake (Figure 7.13)
The controls after nine days were made up chiefly of Cyanophyta species,
mainly Lyngbya sp. and Oscillatoria spp. Flasks inoculated with raw sewage showed
a succession of green algal dominance, chiefly Scenedesmus sp. and Chlorella sp.
Flasks receiving primary treated sewage again showed Cyanophyta dominance, mostly
Oscillatoria spp. Mixed liquor additions promoted more growth of diatoms, chiefly
Navicula spp., but still had a high dominance of Oscillatoria spp. Flasks
enriched with secondary non-chlorinated sewage again promoted total dominance of
diatoms, mainly Navicula spp. whereas the addition of final chlorinated and
tertiary treated sewage, perpetuated a Cyanophyta dominance, chiefly Oscillatoria
spp.
7.1.4 Trace Metal Experiments
The fall run of the nutrient enrichment bioassay was incorporated into the
trace metal experiments. The first seven flasks of each series received nutrient
additions equivalent to those in the spring nutrient enrichment bioassay, 1971.
The remaining flasks received combinations of nutrients [NO3(N) and PO4(P)];
trace metals; boron, iron and molybdenum, and the chelator, EDTA. The results
obtained from the trace metal experiments will be discussed on the basis of up-
take of radioactive carbon, because samples allotted for chlorophyll analysis
were too small to yield accurate growth trends. Results will be discussed on a
comparative basis, that is the effect of the addition of a nutrient and trace
metal or chelator, will be compared to that of the nutrient addition alone.
BIOASSAY RESULTS, SEWAGE ENRICHMENT EXPERIMENTS AFTER NINE
DAYS GROWTH ON KALAMALKA LAKE WATER,1971. Figure 7.12
BIOASSAY RESULTS, SEWAGE ENRICHMENT EXPERIMENTS AFTER NINE
DAYS GROWTH ON WOOD LAKE WATER,1971. Figure 7.13
(a) Osoyoos Lake
The fall run of the nutrient enrichment bioassay showed similar growth
trends to that seen in the spring run. NO3(N) additions of 0.7 mg/liter showed
growth equal to that of the control, whereas at the higher concentration of 1.2
mg/liter, growth was observed to be less than that of the control. Phosphorus
addition at the lowest concentration (0.03 mg/liter) showed growth inhibition,
whereas at the higher concentration (0.09 mg/liter) growth was stimulated beyond
that of the control. Addition of NO3(N) and PO4(P) together at both concentrat-
ions, showed the greatest growth.
Stimulation of algal growth was evident with boron additions at the lowest
concentration, whereas at higher concentrations growth was inhibited (Table 7.1)
An increase in algal growth was noted when boron and NO3(N) were added to test
samples. Additions of PO4(P) at the lower concentration with boron at both con-
centrations, 10 and 100 g/l, stimulated growth beyond that of phosphorus addit-
ions alone, but to a lesser degree than with nitrogen and boron additions. Phos-
phorus additions at the highest concentration and nitrogen and phosphorus addit-
ions together at both concentrations, together with boron at both concentrations,
all showed algal growth less than that of the controls (Table 7.1).
Addition of EDTA at the lowest concentration showed growth less than the
control, whereas at the highest concentration algal growth was much higher than
the control (Table 7.1). Nitrate additions at both concentrations along with
both levels of EDTA showed stimulation of algal growth when compared with flasks
with NO3(N) additions alone. Flasks receiving PO4(P) at the lower concentration
along with EDTA at both concentrations, showed growth stimulation, but to a less-
er degree than that of NO3(N) and boron additions. Phosphorus additions at the
highest concentration along with both concentrations of EDTA proved to be inhib-
itory to algal growth (Table 7.1). Addition of NO3(N) and PO4(P) together at the
lowest concentration and with EDTA at the lowest concentration showed no increase
in algal growth, whereas the highest concentration of NO3(N) and PO4(P) together
and EDTA showed marked increases in growth (Table 7.1).
Additions of EDTA and iron, stimulated growth in all flasks, with the
greatest response noted with the addition of higher concentrations of EDTA and
iron and NO3(N) and PO4(P) together (Table 7.1).
Growth was stimulated in most flasks with the addition of molybdenum. The
greatest response occurred with the addition of the highest concentration of
molybdenum along with the addition of the higher concentration of NO3(N) and
PO4(P) together (Table 7.1).
(b) Skaha Lake
The fail run of the nutrient enrichment bioassay on one mid-lake station in
Skaha Lake showed similar results to that of the spring run, except that the
TABLE 7.1
RESULTS OF TRACE METAL EXPERIMENTS 1971 - OSOYOOS LAKE
TABLE 7.2
RESULTS OF TRACE METAL EXPERIMENTS 1971 - SKAHA LAKE
Results of Trace Metal Experiments, 1971.
+ ( 1.0) growth greater than controls.
- ( 1.0) growth less than controls.
e (=1.0) growth equal to controls.
addition of nitrogen at the highest concentration (2.1 mg/liter) showed the
greatest production of algae (Table 7.2),
With the addition of boron at the lowest concentration, algal growth was
stimulated beyond that of the control, whereas with the higher addition of
boron, growth was inhibited (Table 7.2). Nitrate additions at the lowest
concentration with boron at both concentrations and NO3(N) and PO4(P) together
at higher concentration of boron were all stimulatory to algal growth. All
other nutrient additions with boron additions were inhibitory to algal growth
(Table 7.2).
With the addition of EDTA at the lowest concentration, growth was less
than the control, whereas at the highest concentration, growth was stimulated
beyond that of the control (Table 7.2). Nitrate addition at both
concentrations with EDTA additions, were inhibitory to algal growth, whereas
growth was stimulated with all other NO3(N) and EDTA additions. Phosphate
and EDTA additions together in the lower concentrations showed growth less
than that of PO4(P) additions alone. Addition of the lowest concentrations
of phosphate along with the higher concentration of EDTA promoted growth
slightly above that of PO4(P) addition alone. The opposite trend occurred
for the highest addition of phosphorus with slight growth stimulation and
inhibition with the lower and the higher concentrations of EDTA respectively.
Additions of NO3(N) and PO4(P) together at the highest concentrations along
with EDTA at the higher concentration, produced the greatest production of
algae as compared to all other nutrient additions with boron (Table 7.2).
The controls and flasks receiving additions of PO4(P) at the lowest
concentration, and EDTA and iron at higher concentration, together with
flasks inoculated with PO4(P) highest concentration and iron at both
concentrations, all produced algal growth less than the flasks without EDTA
and iron. In all other flasks. Growth was greater than the controls, with
the greatest response being with the additions of the highest concentration
of NO3(N) and both concentrations of NO3(N) and PO4(P) together, along with
EDTA and iron at both concentrations (Table 7.2).
In all cases, the addition of Molybdenum was inhibitory to algal growth,
except for the addition of NO3(N) and PO4(P) together at the highest
concentration along with the lowest concentration of molybdenum. In this
instance, growth was stimulated a little beyond the flask with NO3(N) and
PO4(P) alone (Table 7.2)
(c) Okanagan Lake
The fall run of the nutrient enrichment bioassay, 1971, showed
stimulation of growth with all nutrient additions. Nitrate additions at the
highest concentration showed the greatest production of algae. Flasks
inoculated with PO4(P) at the lowest concentration showed the next highest
production of algae. Nitrate
additions at the lowest concentration produced good growth, but to a lesser
degree than PO4(P) additions at the lowest concentration (Table 7.3). Addition
of PO4(P) at the highest concentration and additions of NO3(N) and PO4(P)
together at both concentrations, all showed equal growth promotion to slightly
above that of the controls (Table 7.3).
Some stimulatory effect on algal growth was evident with boron additions
alone at both concentrations (Table 7.3). Growth inhibition was observed with
the additions of NO3(N) and boron in all combinations. PO4(P) additions in the
lowest concentration and the highest concentration along with additions of
boron in the lowest and highest concentrations were stimulatory to growth,
whereas all other PO4(P) and boron additions were inhibitory to algal growth.
Additions of NO3(N) and PO4(P) together at both concentrations along with both
concentrations of boron, all promoted the greatest algal growth (Table 7.3),
Addition of EDTA in most all cases showed greater growth than that of the
controls. EDTA additions alone showed increased growth with the increased
concentration of EDTA. NO3(N) additions along with both concentrations of EDTA
showed growth stimulation with the greatest response with the addition of the
lowest concentration of NO3(N) along with the highest concentration of EDTA. All
PO4(P) additions along with EDTA showed approximately the same amount of growth
stimulation except for the addition of PO4(P) at the highest concentration along
with EDTA at highest concentration, which was only slightly above the others
Flasks receiving additions of NO3(N) and PO4(P) together showed a similar trend
to other flasks with the addition of EDTA (Table 7.3).
Additions of EDTA and iron alone showed growth stimulation with the great-
est response being the addition at the highest concentration. In all cases,
NO3(N) additions alone with EDTA and iron were inhibitory to algal production,
except for the addition of NO3(N) at the highest concentration along with the
lowest concentration of EDTA and iron (Table 7.3). PO4(P) additions along with
EDTA and iron showed growth inhibition whereas additions of NO3(N) and PO4(P)
together, along with EDTA in all combinations showed the greatest growth
stimulation (Table 7.3).
(d) Kalamalka Lake
The effects of trace metals on algal growth could not be observed on the
sample taken from Kalamalka Lake as initial phytoplankton populations were too
low to yield distinguishable effects. These results lend support to the state-
ment that Kalamalka Lake is the most Oligotrophic lake in the Okanagan Basin.
(e) Wood Lake
The fall run of the nutrient enrichment bioassay, 1971 showed growth stim-
ulation with all nutrient additions, with the greatest algal growth in flasks
with NO3(N) at highest concentrations, and NO3(N) and PO4(P) together at highest
concentrations (Table 7.3).
TABLE 7.3
RESULTS OF TRACE METAL EXPERIMENTS 1971 - OKANAGAN LAKE
TABLE 7.4
RESULTS OF TRACE METAL EXPERIMENTS 1971 - WOOD LAKE
Results of Trace Metal Experiments, 1971.
+ ( 1.0) growth greater than controls.
- ( 1.0) growth less than controls.
e (=1.0) growth equal to controls.
All additions of boron, alone or in combination with nutrients, showed growth
equal to or less than that of the controls (Table 7.4).
Growth patterns with EDTA and nutrients followed different trends from
those observed with boron additions. In this case, growth increased with all
EDTA additions except for PO4(P) at the highest concentration and EDTA at the
lowest concentration. Additions of NO3(N) and PO4(P), together at the highest
concentration, along with EDTA both concentrations showed the greatest algal
growth (Table 7.4).
Similar growth patterns were observed with the addition of EDTA and iron
to that of additions of EDTA, except there was greater production of algae in
this series. Every flask was stimulated beyond that of a nutrient addition
alone, except for the addition of PO4(P) at the lowest concentration along with
EDTA at the lowest concentration, and PO4(P) at the highest concentration along
with EDTA at the highest concentration, which were slightly below the control
(Table 7.4).
The highest yield of algae was produced with the addition of nutrients
and molybdenum as compared to all other trace metal and chelator additions in
Wood Lake (Table 7.4). The greatest growth response was observed in flasks
with additions of NO3(N) at highest concentration and NO3(N) and PO4(P) together
at the highest concentration along with both concentrations of molybdenum.
7.1.5 General Discussion
Results from four different experiments conducted on the six main lakes in
the Okanagan Basin permitted an evaluation of the role of nutrients in
regulating algal growth. Further information was gained on the causes of
eutrophication of localized areas within lakes that are currently exhibiting
nuisance conditions.
Kalamalka Lake and the main water mass of Okanagan Lake are currently in a
nutrient deficient state. This was indicated by results from both the
nutrient enrichment and pure culture bioassay experiments. In these lakes,
NO3(N) and PO4(P) when added together, stimulated the greatest algal growth.
When each nutrient was added alone, little algal growth occurred. Results
from the pure culture bioassay experiments indicated a paucity of available
nutrients, since little growth of the test algae was noted when added to
filtered water.
Certain localities of Okanagan Lake exhibited nutrient-rich
characteristics, namely in the Vernon Arm, Armstrong Arm and the near-shore
water mass in the vicinity of Kelowna and Summerland. At these localities,
NO3(N) when added alone was in most instances, stimulatory to algal growth,
while PO4(P) additions were not. These results indicate a sufficient supply of
PO4(P) and a deficiency of NO3(N). The growth of test algae in the pure
culture bioassay experiments was moderate to high at all these localities,
again indicating a 'residual' nutrient supply.
Skaha Lake appeared to be limited more by NO3(N) than PO4(P), for most
additions of NO3(N) were stimulatory while PO4(P) additions were not. Curr-
ently, the most productive region of Skaha Lake is in the north end off the
mouth of Okanagan River, where yields of test algae were the highest among
lakes tested. Much of the main water mass of Skaha Lake exhibited
nutrient-rich characteristics with no apparent PO4(P) limitation.
Vaseux and Osoyoos Lakes appeared to be limited by both NO3(N) and
PO4(P), for the addition of both nutrients together, produced the greatest
algal yield. The noted yield was considerably higher than that observed in
Kalamalka and Okanagan Lakes, largely attributable to a much higher
standing stock of phytoplankton in Vaseux and Osoyoos Lakes. The station
located off the mouth of the Okanagan River in Osoyoos was more productive
than the station located in the central portion of the lake, showing a
greater response to NO3(N) than to PO4(P) additions. Results of the pure
culture bioassay experiments also indicated that the most productive region
of Osoyoos Lake was off the mouth of the Okanagan River, where moderate to
high yields of the test algae were obtained. Vaseux Lake showed moderate
yields of algae, indicating some nutrient availability at the time of the
experiments.
Results from experiments conducted on Wood Lake water indicate it is
one of the most productive (eutrophic) lakes in the valley. Additions of
PO4(P) had no effect whatsoever, while NO3(N) additions promoted an
excellent algal growth response. Results from the Pollution Control Branch
experiments showed that an ample supply of available nutrients are present
in Wood Lake throughout much of the growing season.
Historically, sewage treatment has been carried out primarily for
community health reasons, and has not been concerned with aesthetic values
such as increased plant growth. Only the water quality deterioration of
many of the larger lakes to a point of aesthetic unacceptability has
created the demand for research and control in this area.
Results from the sewage enrichment experiments strikingly illustrated
the fertilizing capacity of domestic wastes when discharged to lakes in the
Okanagan Valley. Preliminary results indicated that biological treatment
of wastes often only increases the availability of plant nutrients, and
hence does very little to ameliorate an algal nuisance problem. Increasing
the amount of sewage added to lake water simply changed the direction of
algal succession toward a blue-green algae dominance.
The trace metal experiments gave some dues as to the possible role of
trace metals and a chelator in regulating phytoplankton growth, but no
definitive conclusions can be drawn at this time from these preliminary
experiments.
7.2 PHYTOPLANKTON
No detailed phytoplankton enumeration was conducted as part of the
present study. Fortunately, the work of Stein and Coulthard (1971) included
some enumeration data of dominant and sub-dominant phytoplankton in each of
the main valley lakes (Table 7.5).
The phytoplankton populations in Wood Lake are characterized by the
dominance of blue-green algae in most samples, at all depths, throughout
the season. Oscillatoria sp. was the dominant species, while Aphanaizomenon
was common during the summer. A few diatoms occur in early spring in Wood
Lake, but these are quickly replaced by a blue-green algae dominated
assemblage. The populations were among the largest recorded, averaging
7,900 cells per milliliter.
In Kalamalka Lake, phytoplankton populations are sparce - 700 cells
per milliliter, and diatoms are the dominant form, chiefly Asterionella
formosa, Fragilaria crotonesis, and Synedra acus. Green algae are not too
prevalent in Kalamalka. However, the phytoflagellates comprise over 51%
of the total population in early summer and early fall. The more important
species are Cryptomonas ovata, Chromulina spp and Dinobryon certularia.
Okanagan Lake phytoplankton is dominated chiefly by diatoms with some
blue-green algae, but there is considerable variation from station-to-
station. Phytoplankton density is generally low, averaging approximately
1,500 cells per milliliter as compared to 7,000 to 8,000 cells in Wood and
Osoyoos Lakes respectively (Table 7.5). Currently, the dominant diatoms in
Okanagan Lake are Fragilaria crotonesis , Asterionella formosa and Melosira
italica. The blue-green algae common in mid-summer and in the fall are
chiefly Aphanotheca nidulans, Anabaena flos-aquae and Lyngbya limnetica.
The dominant phytoflagellate is Cryptomonas ovata.
Phytoplankton of Skaha Lake is composed chiefly of diatoms with a blue-
green algal pulse in late August and early September. Average phytoplankton
density is about 3,700 cells per milliliter. The dominant diatoms in Skaha
Lake are Asterionella formosa, Fragilaria crotonesis and Cyclotella comta.
In the summer these diatom species are replaced by Melosira italica, and
Tabellaria spp. The dominant blue-green algae are Aphanizomenon flos-
aquae, Aphanotheca microscopica and Anabaena circinalis.
The phytoplankton succession in Osoyoos Lake is characterized by a
spring pulse of diatoms, a summer bloom of blue-greens and phytoflagellates
and a return to diatoms in the fall. The principal diatom species in
Osoyoos Lake are Asterionella formosa, Fragilaria crotonesis, Cyclotella
comta and Melosira italica. The dominant phytoflagellate was Cryptomonas
ovata. The blue-green algae recorded commonly are Oscillatoria spp.,
Lyngbya limnetica and Aphanizomenon flos-aquae.
TABLE 7.5
PHYTOPLANKTON BY SEASONS*
* Phytoplankton density, seasonal succession by group, and dominant phytoplankton species in the Okanagan main valley lakes (after Stein and Coulthard, 1971).
NOTE: Dominant group listed first: = means equal numbers of each.
BG - bluegreen algae: D - diatoms: Ph - phytoflagellates
DOMINANT PHYTOPLANKTON SPECIES
The previous paragraphs have outlined in some detail the more common
phytoplankton species in the main valley Okanagan lakes. In those lakes
exhibiting eutrophic characteristics, i.e. Wood, Osoyoos Lakes; blue-green
algae tend to be dominant throughout much of the summer and fall periods. In
those lakes exhibiting less eutrophic conditions, diatoms and phytoflagellates
were the most abundant groups. In Skaha, Wood and Osoyoos Lakes, where a
moderately high concentration of PO4(P) occurs at spring overturn, there was a
rapid growth of diatoms followed by a pulse of blue-green algae, whose density
appeared to a large extent dependent upon the initial concentration of
available PO4(P). In Wood Lake where there was an over-abundance of PO4(P) at
spring overturn (80 ug/ liter), blue-green algae tended to dominate the
phytoplankton assemblage from spring to early fall. In Okanagan and Kalamalka
Lakes, where the concentration of PO4(P) at spring overturn is low ( <10
ug/liter), diatoms dominate the spring pulse, with phytoflagellates common
during summer and with a return to diatom dominance in the fall. The observed
seasonal succession of phytoplankton provides further evidence of the trophic
character of the Okanagan main valley lakes.
7.3 ATTACHED ALGAE AND ROOTED AQUATIC VEGETATION
Since lake water quality changes are often reflected in growth of rooted
aquatic vegetation and periphyton, which can in turn have a notable effect on
people's use of the water body; the extent and magnitude of this growth was
studied in 1972. Attention was focused upon the determination of biomass and
relative growth rate of attached algae (periphyton). Also included in the
study was a cursory examination of the nature of the substratum (sand, rock,
gravel) of the littoral zone of the main valley lakes and documentation of the
extent of use of this zone by aquatic macrophytes.
Vaseux Lake is most affected by littoral development, with approximately
50% of the lake area included in the 0 to 6 meter contour (Table 7.6).
Okanagan Lake, North and Vernon Arms, had about 28% of their surface area
comprised of littoral zone, and in Osoyoos Lake approximately 23% of its area
was included in the 0 to 6 meter contour of the littoral zone. Skaha Lake had
extensive littoral benches along the eastern shoreline which comprised
approximately 15% of total lake area. The remaining basins of Okanagan, Wood
and Kalamalka Lakes are steep sided and have a negligible littoral region,
comprising about 5 to 9% of the total lake surface area. Emergent and
submergent vegetation covers almost the entire littoral zone in Vaseux Lake,
but in the other main valley lakes, epilithic and epipetic benthic diatoms are
the dominant vegetation.
The dominant emergent macrophyte in all lakes was Scirpus validus.
Nymphaea odorata and Nuphar luteum were dominant floating leaved plants,
commonly found in the littoral zones of Vaseux and Osoyoos Lakes. The dominant
submergent plants,
TABLE 7.6
LAKE AREA, LITTORAL AREA. AND PERCENT OF LAKE AREA
COMPRISED OF LITTORAL
often causing nuisance conditions were Myriophyllum exalbescens, Potomogeton
richardsonii and Potomogeton crispus. Areas currently exhibiting extensive
weed beds, where harvesting has either been carried out or has been
proposed, are Vernon Arm and Kelowna shoreline south of the floating bridge
in Okanagan Lake; the south end of Wood Lake; patches along the east shore
of Skaha Lake; Vaseus Lake, and along the west shore, north and middle
basins of Osoyoos Lake (Table 7.7).
Results of periphyton studies indicate that Wood Lake produces the
greatest yield of periphyton per meter squared of littoral zone, and the
Vernon Arm of Okanagan Lake produces the second highest yield (Table 7.8).
Yield of periphyton at both stations in Vaseux Lake and off the mouth of the
Okanagan River in Skaha Lake, and in Osoyoos Lake were also high, ranking
third and fourth respectively (Table 7.8). (See Maps 3 to 10). The
average periphyton growth at other lake stations was substantially less than
the above noted, with values varying from 0.3 to 0.8 mgm/cm2. The heavy
periphyton growth noted in Wood, Skaha, Vaseux and Osoyoos Lakes was, in
most cases, at stations located either in the vicinity of direct known
sewage effluent discharges, or very close to the plume of the Okanagan
River. The lowest average yield of periphyton was noted in Kalamalka Lake
and at 6 of the 8 stations in Okanagan Lake (Table 7.8). Low growth was
also noted at stations along the east shore of Skaha Lake. This was thought
to be due to a paucity of nutrients along the eastern shoreline, as the main
flow of the Okanagan River is directed to the western shoreline by a small
training dyke. The situation noted in Skaha Lake, where one station
exhibits high growth and others very low growth, is similar to that noted in
Okanagan Lake where 6 of the 8 stations showed very low growth, while those
in more eutrophic situations, i.e. located adjacent to the Kelowna and
Vernon Arm areas, showed much higher growth.
There were general trends observed in the seasonal growth and succession
of periphyton assemblages in all main valley lakes (Maps 3 to 10).
1. The maximum growth occurred in May or early June and consisted chiefly of diatoms.
2. A second, smaller growth pulse occurred in late August and was dominated by green or blue-green algae.
3. Dominant species in spring algal assemblages tended also to be dominants in the fall assemblage.
4. Most peaks in the plot of chlorophyll-a values coincided with the second growth peak in mid-August.
5. The lowest periphyton production occurred in most lakes in the period from mid-July to early August
6. The summer algal assemblages at highly productive stations were generally dominated by Cladophora glomerata or oscillatoria spp.
7. There was a high rate of occurrence of blue-green algae at all stations located in nutrient-rich areas. In more Oligotrophic areas, diatoms were the principal group throughout the growing season.
TABLE 7.7
TENTATIVE IDENTIFICATION OF AQUATIC MACROPHYTES
IN THE OKANAGAN MAIN VALLEY LAKES
TABLE 7.8
AVERAGE NET PRODUCTION RATE OF PERIPHYTON FROM APRIL 19 TO SEPTEMBER 17 (152 DAYS)
ON GLASS SLIDES IN THE OKANAGAN LAKES.
(SOME SELECTED VALUES FROM THE LITERATURE ARE GIVEN FOR COMPARISON)
A summary of dominant algal species and the annual succession of periphyton in
lakes appears in Table 7.9.
Attempts were made to relate the concentrations of N and P contained in
attached algal cells to available external supplies. Results indicated that
the ratio of N:P in periphyton growing in eutrophic waters was half that found
in less productive stations; 5:1 compared to 14:1 in more Oligotrophic
stations. Highest phosphorus values were noted in the spring samples in
eutrophic locations, while nitrogen concentrations tended to be higher in late
summer and early fall in all lakes.
7.4 BOTTOM FAUNA
When assessing the relation between bottom fauna, lake enrichment and poll-
ution, one must bear in mind that the distribution of benthic invertebrates cannot
be explained completely without taking temperature regime, lake morphology, and
zoogeographical distribution into consideration. Furthermore, among benthic
animals, midges (chironomids) are better indicators of the oxygen level than of
the trophic level. The oxygen level is not absolutely dependent on the primary
production in the upper waters, but is strongly influenced by, (among others) the
relative volume of the deep water in the hypolimnion to that in the epilimnion.
This means that lakes with nearly identical communities of bottom organisms may be
at different trophic levels. A strong correlation between trophic levels and
bottom fauna composition thus cannot always be expected, especially in mesotrophic
lakes. In such lakes, the number and weight of animals per area and the
distribution with depth both of total bottom fauna and of forms characteristic for
different trophic communities, may be more important.
Rawson (Clemens, et al, 1939) conducted a preliminary survey of the bottom
fauna of Okanagan Lake in 1935, concluding that the lake was Oligotrophic, per-
haps even ultra-oligotrophic. Northcote and Larkin (1956) included benthic
grab samples from Kalamalka Lake in their survey of 100 B.C. lakes. Ferguson
(1949) took grab samples from Skaha Lake. Apart from these three brief
surveys, the bottom fauna of the Okanagan main valley lakes has not been
studied in any detail.
7.4.1 Okanagan Lake
A total of 32 stations were sampled in Okanagan Lake in 1969. Species
composition and average number of bottom organisms per square meter of sediment
are presented in Table 7.10. When these data are compared with Rawson's
findings, it is obvious that the lake has become more productive over the past
34 years. Rawson found only 15% of the bottom fauna comprised of oligochaetes,
whereas currently they account for over 50% of the total fauna. There has also
been a significant increase in the total number of chironomids, Iridium, and
other miscellaneous groups. The increase in abundance of oligochaetes together
with the occurrence of deformed chironomids in certain regions of Okanagan Lake
is suggestive of some degree of insecticide pollution (Saether, 1970).
TABLE 7.9
SEASONAL SUCCESSION OF DOMINANT ALGAE IN THE PERIPHYTON OF THE
OKANAGAN MAIN VALLEY LAKES
TABLE 7.10
THE AVERAGE NUMBER OF FAUNA PER SQUARE. METER IN THE OKANAGAN MAIN
VALLEY LAKES. _FROM ALL DEPTHS SAMPLED
The northern region (Vernon, Armstrong Arms), is presently mesotrophic,
based on the distribution and abundance of benthic organisms. Evidence of the
pollution of the Vernon Arm by the Vernon Sewage Treatment Plant effluent was
obtained in a series of stations taken from the mouth of Vernon Creek west to the
vicinity of Okanagan Landing. The character of the fauna changed from one
dominated by oligochaetes; Limnodrilus hoffmeisterii (eutrophic), to more meso-
trophic indicators in the station just adjacent to Okanagan Landing. The mid-
portion of the north basin between Okanagan Landing and Kelowna showed little
change from the condition observed by Rawson nearly 40 years ago, and can still
be considered Oligotrophic. It is interesting that one station adjacent to the
mouth of Shorts Creek, (See Map 8), contained a predominance of mesotrophic
indicator species, as opposed to other stations nearby that showed Oligotrophic
forms. It was Shorts Creek that contributed up to 40% of the total phosphorus
loadings to Okanagan Lake in 1970-71. This high load was largely particulate
matter, and was attributed to extensive logging carried out in this watershed
over the past few years. The relationship seen here is suggestive of moderate
nutrient pollution because of poor land-use practices.
Stations 1 to 6 in Okanagan Lake were close to the pipe which discharges
sewage from the City of Kelowna to Okanagan Lake. One station located very close
to the pipe contained no organisms. Other stations in the immediate vicinity of
the pipe, contained few organisms, but in stations further removed from the pipe,
there was a tremendously large number of organisms of the Oligotrophic type.
Station 29, situated off the boat landing in Summerland, contained a high
number of Limnodrilus hoffmeisterii and together with a presence of Chironomus
thummi type and Procladius indicated a source of pollution to Okanagan Lake at
this station. Stations further south in the basin adjacent to Penticton, the
deeper waters, were typically Oligotrophic in faunal composition.
The bottom fauna of Okanagan Lake has shown considerable change since
Rawson's investigation some 38 years ago. However, the fauna in the deeper water
sediments show no apparent change over the 1935 condition, and the lake as a
whole must still be classified as Oligotrophic in terms of the distribution and
abundance of benthic organisms.
7.4.2 Skaha Lake
The bottom fauna in Skaha Lake is complicated by the presence of both oli-
grotrophic and eutrophic indicator species. This type of distribution of benthic
fauna is not unusual for formerly Oligotrophic lakes, which by the sudden intro-
duction of nutrients, are rapidly eutrophicating. The perplexing occurrence of
Oligotrophic forms may be explained by the high flushing rate from Okanagan Lake
water with the possibility of re-colonization from this lake. This, in combin-
ation with relatively high oxygen levels in the hypolimnion, may account for the
somewhat varied faunal distributions noted in Skaha Lake.
There was a predominance of oligochaetes in Skaha Lake, with
Limnodrilus hoffmeisterii as the dominant species. There were over 9,000
invertebrates per square meter in 1971, which was the highest density
recorded for all lakes sampled in 1971 (Table 7.10). In 1969, the density
was 3,892 per square meter, which was second only to Osoyoos Lake (Table
7.10). Of six chironomid species found, very few were indicative of
eutrophic conditions. The absence of more eutrophic-indicating species may
be the result of currents near the bottom which wash away some potential
food such as detritus, thus creating a situation where food content is not
high enough to support chironomid populations. Hence, forms adapted to
less nutrient-rich sediments predominate.
7.4.3 Osoyoos Lake
The north and central basins of Osoyoos Lake are, according to the
composition of the bottom fauna, moderately eutrophic and strongly
eutrohpic, respectively. The central basin appears to have been enriched
by surrounding communities. The northern basin is divided into two sub-
basins with a pronounced underwater ridge between. This ridge may explain
the difference between samples taken between the two northern sub-basins.
The average number of bottom fauna per square meter of sediment surface in
Osoyoos Lake was the highest recorded in the main valley lake system in
1969 (Table 7.10).
7.4.4 Kalamalka Lake
In 1935 Rawson found Kalamalka Lake to be a typical Oligotrophic lake,
slightly richer than Okanagan Lake. He also noted that chironomids made
up over 95% of the benthic fauna in the lake. In 1971, chironomids made
up only 55% of the fauna. Thus, a significant shift in the faunal
composition has taken place over the past 38 years.
The abundance of organisms per square meter in 1935 was of the same
order of magnitude as those found during the current survey. One station
situated about 50 meters from the mouth of Coldstream Creek in the northern
part of Kalamalka Lake, showed some degree of mild pollution. Chironomus
f.l. flumosus and C.f.l. anthracinus together with oligochaetes at a
density of over 1,000 per square meter, indicated some enrichment from this
stream. This finding correlates well with observations of nuisance rooted
aquatic plant growths off the mouth of Coldstream Creek in 1971-72.
Coldstream Creek drains an extensive cattle range area and is currently
under intensive agricultural development.
Kalamalka Lake, on the basis of the distribution and abundance of
benthic invertebrates, remains a typical Oligotrophic lake. The changes
that have occurred in Kalamalka Lake since Rawson's investigations in
1935, are of much smaller magnitude than those found in Okanagan Lake.
7.4.5 Wood Lake
In 1935, Rawson found the benthic fauna of Wood Lake to be characteristic
of a eutrophic lake; very high densities of oligochaetes and chironomids. He
noted that in all 8 samples he collected, there were always more than 1,000
oligochaetes per square meter, and at a depth of 23 meters he found as many as
23,000 per square meter. Today the lake has very few organisms in the
sediment (Table 7.10). In most areas no oligochaetes occur at all, and only a
few specimens of Chironomus attenuatus. Two stations located near the outlet
are obviously influenced by water entering the lake from Kalamalka Lake, but
never-the-less have fauna typical of a eutrophic lake. However, even at these
stations the number of oligochaetes was very much less than 1,000 per square
meter (Table 7.10). The current limnological condition of Wood Lake does not
alone explain the disappearance of what was undoubtedly a formerly rich fauna.
The rate and duration of oxygen depletion is not so high as to explain the
apparent paucity of invertebrates in Wood Lake. Saether and MacLean (1972)
conclude that the only explanation must be the existence of some toxic
compound in the sediments.
The arthropods are much more resistant to toxic compounds than most soft-
bodied invertebrates, with the exception of insecticides which have little in-
fluence on worms and molluscs (Liebmann, 1960). Thus, it is suggested that
the alleged toxic compound is not an insecticide, thus giving chironomids
something of a comparative ecological advantage. High levels of mercury in
the sediments do not alone seem to be of sufficient toxicity to cause the
apparent decline.
7.4.6 General Summary
In summary, the distribution and abundance of benthic invertebrates has
provided a trophic characterization of the main valley lakes that is
consistent with current understanding of the overall biological production in
these lakes. On the basis of benthic invertebrate abundance and species
composition, the lakes can be ranked as follows:
Species Composition
Abundance________(% Eutrophic Indicator Species)
1. Skaha HIGH
2. Osoyoos
3. Okanagan
4. Kalamalka
5. Wood LOW
7.5 ZOOPLANKTON
The varying nutrient load to the Okanagan main valley lakes and wide spec-
trum of trophic conditions offer an excellent opportunity to assess the response
of certain Zooplankton populations to varying trophic states. Rawson studied the
Zooplankton in Okanagan Lake in 1935. Northcote and Larkin (1956) reported
1. Wood
2. Osoyoos
3. Skaha
4. Okanagan-Kalamalka
on collections from Kalamalka Lake and Ferguson (1949) from Skaha Lake. Little
or no work has been done on the remaining main valley lakes. Zooplankton studies
as a part of the Okanagan Basin Study program consisted of a survey of Okanagan,
Skaha and Osoyoos Lakes in September of 1959, and of these three plus Wood and
Kalamalka Lakes, in August/September of 1971. The salient findings of these
studies are reported below. Details of the survey results are listed in Appendix
F and summarized in Tables 7.11 and 7.12.
7.5.1 Okanagan Lake
In total, thirteen species of crustacean plankton were found in the main
valley lakes, and all of them were presented in Okanagan Lake (Table 7.11). Of
four copepod species found, Cyclops bicuspidatus thomasi and Diaptomus ashlandi
were the most abundant, contributing to about 60 and 30 % respectively of the
total number of plankton species. Out of nine cladoceran Zooplankton species,
Daphnia thorata was the most abundant, but its contribution to the total number
of crustaceans was no greater than 1 to 2%. The second most abundant cladoceran
was Daphnia longiremis. The remaining cladoceran species were in low number and
as a rule less than 0.3% of the total (Table 7.12).
On the basis of vertical series taken in September 1969, it was found that
most species of Zooplankton were distributed in the upper-most 25 meter layer.
The most abundant species, Diaptomus ashlandi and Cyclops bicuspidatus thomasi
were distributed throughout the 0 to 50 meter layer. The only exceptions were
the nauplii of C. bicuspidatus thomasi which showed a maximum density in the 25
to 50 meter layer of water. Of the total plankters, 89% were located above the
50 meter depth contour.
The horizontal distribution of plankton in Okanagan Lake was more or less
uniform throughout the central and most of the northern part of the lake in
1969, with densities of between 100 to 200 individuals per square centimeter
(Table 7.12). The lowest amount of Zooplankton was found in the north arm of
Okanagan Lake and this may be explained by the shallow depth at this station. A
significantly higher number of Zooplankton were found in the south end of
Okanagan Lake in 1969, but not in 1971.
The wide variation of the horizontal distribution of plankton as measured
by settled volume (mm3/cm2) can be seen in Map 2. The highest plankton volume
were found in September 1969, in the southern basin transects 1 to 3, with 14-20
mm3/cm2. In the vicinity of Kelowna, there were between 9 to 17 mm3/cm2 settled
volume of Zooplankton, while in the northern basin there were over 21 mm3/cm2.
In most of the remaining lake area, the average volume of plankton was between 5
and 11 mm3/cm2. The very high density of settled plankton in the southern basin
in 1969 was due, mainly, to the number of copepodids of C. bicuspidatus thomasi
and D. ashlandi. In August 1971, the greatest density of settled plankton was,
as in 1969, located in the vicinity of Kelowna, and in the most
TABLE 7.11
LIST OF SPECIES FOUND IN NET PLANKTON OF LAKES OKANAGAN AND KALAMALKA
IN THE PERIOD FROM 1935 TO 1971. (1935 DATA TAKEN FROM RAWSON (1939)
Identifications by Dr. G.C. Carl; 1951 Data, Identifications by Present
Authors From Samples Kindly Provided by Dr. T.G. Northcote)
TABLE 7.12
NUMBER PER cm2 AND PERCENT OF TOTAL COMPOSITION OF ZOOPLANKTON SPECIES
IN FIVE OKANAGAN MAIN VALLEY LAKES
northern basin (Map 2). No above average volumes of Zooplankton were
found in the southern basin, as in September 1969. In both 1969 and in
1971, the higher number of adults and lower number of copepodids in the
northern end of the lake indicated a more advanced stage of population
development in this region.
There were significant differences between the density of plankton in
the 0 to 5 meter layer between inshore and offshore waters. The
concentration of planktonic crustaceans in the inshore waters was, on the
average, only 50% of that found in offshore waters in Okanagan Lake.
7.5.2 Skaha Lake
No significant difference was found in species composition and relative
abundance of these species between Skaha and Okanagan Lakes. of the
thirteen crustacean plankton found in Okanagan Lake, twelve were present in
Skaha Lake with C. bicuspidatus and D. ashlandi being the dominant species
(Table 7.12). Among the cladoceran plankton, D. leuchtenbergianum and D.
longiremis were the most abundant. Between 15 to 19% of the population of
Zooplankton consisted of adults in Skaha Lake, while only 0.7 to 1.0 were
adults in the population in Okanagan Lake, (Table 7.12). Because of this,
there were high settled plankton volumes found in Skaha Lake in both years,
explainable in part by structural differences in the population. In
addition to more adults in the population, there were a greater number of
individuals per square cm. in Skaha Lake in both years (Table 7.12).
7.5.3 Osoyoos Lake
The crustacean plankton of Osoyoos Lake resembled that found in Skaha
Lake, both in species composition and in population structure (Table 7.12).
The total number of zooplankters averages 161 individuals per square cm. in
September 1969, and only 76 per square cm. in August 1971, (Table 7.12).
These densities were much lower than the numbers found in Skaha Lake and
even lower than those found
in Okanagan Lake. The corresponding settled volumes of plankton were
much higher (Map 2), approximately 25.9 and 10.9 mm3/cm2 in 1969 and 1971
respectively.
This difference in density and settled volume is related to the high
percentage of copepodids and adults in the populations of C. bicuspidatus
and thomasi, and D. ashlandi in Osoyoos Lake.
7.5.4 Kalamalka Lake
Nine species of crustacean plankton were found in Kalamalka Lake with
C. bicuspidatus thomasi and D. ashlandi the dominant species, representing
56.3 and 31.3% of the population respectively (Tables 7.11 and 7.12) Very
few C. bisucpidatus adults were found in Kalamalka Lake. 98% of the
population of D. ashlandi was composed of copepodids. This age structure
was very similar to that found in Okanagan Lake.
The number of cladocerans found in Kalamalka Lake were much more numerous
here than in Okanagan Lake. Daphnia longiremis was the most abundant cladoceran
in Kalamalka Lake.
The distribution of crustacean plankton throughout the lake was uniform,
ranging from 101 to 169 individuals per square cm., with a lake average of 136
per square cm. (Table 7.12). Correspondingly, the settled volume ranged from 7.8
to 13.3 mm3/cm2 with a lake average of 10.9 (Map 2).
7.5.5. Wood Lake
Only six Zooplankton species were found in Wood Lake with C. bicuspidatus
thomasi and D. ashlandi being dominant. Their percentage contribution to the
total population were 55.6 and 41.5% respectively. Only three species of clad-
ocerans were encountered in this lake, and together constituted no more than 2.2%
of the total crustacean population. The average number of individuals per square cm. was 139 in 1971 (Table 7.12). The high settled plankton volume of 31.3 mm3/cm2, when compared to the low number of adults in the population and to the large amount of phytoplankton that could not be removed (Map 2).
7.5.6 General Discussion
It is interesting to compare the present study findings with those of Rawson
in 1935. Additional data gathered in 1951 about the crustacean Zooplankton of
Okanagan Lake is presented for comparison (Table 7.11). Diaptomus ashlandi and
C. bicuspidatus thomasi, currently the dominant forms in both Okanagan and
Kalamalka Lakes were also dominant forms in both 1951 and 1935 (Table 7.11). By
perusal of this table, it can be seen that little change has occurred since 1935
in the species composition of crustacean plankton. The only significant
difference between 1935 and 1969/71 samples seems to involve Zooplankton
abundance.
The average volume of settled plankton from eleven vertical hauls taken by Rawson between July and August 1935 in the southern, central and northern regions of Okanagan Lake was 1.4 cm /haul or 2.8 mm3/cm2. Samples taken in September 1969 and in August 1971 using a comparable net showed an average density of 13.3 and 7.8 mm3/cm2, respectively, or approximately 4.8 and 2.8 times more Zooplankton now than were present in 1935. Even assuming some sampling error or incompatability
of methods, these values are a valid indication that there has been an increase
in the abundance of Zooplankton in Okanagan Lake since Rawson's 1935 studies. As
noted previously, this increase in the density of Zooplankton is paralleled by an
eight-fold increase in the total abundance of bottom organisms from 1935 to 1969
(Saether, 1970). (See also Section 7.4.1).
It is also interesting to compare the number of crustacean Zooplankton in
the Okanagan Lakes to those of several Laurentian Great Lakes (Table 7.13).
Lakes of the Okanagan Valley appear richer in plankton than Lake Superior, but
certainly poorer than Lakes Erie and Ontario. Figures for Skaha, Osoyoos and
Wood Lakes can
be interpreted as being quite high if one bears in mind that the very
high flushing rate of Skaha and Osoyoos Lakes do not favor the
accumulation of poankton produced in the lake. In addition, very low
oxygen concentrations in the hypolimnion of Osoyoos and Wood Lakes
restricts the inhabitable layer to approximately the upper 20 meters as
compared to 50 meters in the remaining lakes.
TABLE 7.13
AVERAGE NUMBERS OF ZOOPLANKTONIC CRUSTACEANS IN THE
GREAT LAKES AND OKANAGAN BASIN LAKES
7.6
FISHES
Fish serve as convenient indicators, both temporally and spatially,
of the sum of general effects of eutrophication in lakes. It has been
known for some time that fishes respond to changes in the trophic nature
of lakes, but their use as indices of eutrophication has only recently
been considered (Larkin and Northcote, 1969). One of the objectives of
the fishery program was to examine the present state of eutrophication
using fish as indices, and to check selected species of fish for
chlorinated hydrocarbons, heavy metals and other possible contaminants.
Only aspects pertaining to the current state of eutrophication of these
lakes is reviewed in this report. The heavy metal content of fish flesh
and consideration of the abundance of kokanee spawning stocks will be
part of two other technical supplements; Water Quality (VI) and
Fisheries (IX) respectively.
A total of 26 species of fish were taken during the 1971 sampling
program on Okanagan Basin lakes (Table 7.14). Nine of the 26 species
were caught in all lakes sampled. These nine include mountain whitefish,
rainbow trout, kokanee, largescale sucker, carp, squawfish, peamouth
chub, chiselmouth, and prickly sculpin. Representatives of the catfish,
perch, bass and sunfish families were confined to the lower two lakes in
the system - Vaseux and Osoyoos, with the exception of the pumpkinseed,
which were found in Skaha Lake as well.
TABLE 7.14
SPECIES1 OF FISH FROM OKANAGAN BASIN LAKES AT DESIGNATED STATIONS2 DURING THE 1971 SURVEY
1 Listed as given in Carl et al.(1967) except for kokanee which herein is recognized as a distinct form. 2 See Figure 1 for name and location.
7.6.1 Within-Lake Comparisons of Relative Abundance
In larger lakes where a number of sampling stations were established, some
interesting intra-lake differences were noted pertaining to relative abundance of
fishes. These data (Table 7.15), point out some of the intra-lake variations of
productive capacity, particularly in the larger lakes, as illustrated by fishes
which provide a good total view of the effects of trophic level. Kalamalka,
Okanagan and Osoyoos Lakes are discussed below in this regard.
(a) Kalamalka Lake
Two stations were sampled in Kalamalka Lake (Figure 3.4). The south station
consistently showed larger catches than did the northern station for each of the
seasons and most of the species, especially peamouth chub (Table 7.15). Statist-
ical analysis (Chi-square) indicated that the differences in relative abundance
between stations was highly significant in Kalamalka Lake (p < 0:001)
(b) Okanagan Lake
Eight stations (Figure 3.4), were sampled in the spring, summer and fall in
Okanagan Lake. The north station had the highest total catch (Table 7.15) which
was chiefly the result of large kokanee catches in the autumn and lake whitefish
throughout the netting period. Centre, Kelowna and Peachland stations were among
the lowest in total catch. Catches of rainbow trout, mountain whitefish and lake
whitefish were generally higher in the southern stations than in the northern or
central stations.
After excluding kokanee and peamouth chub (schooling species, probably not
caught in gill nets as independent individuals), a series of Chi-square and F.
tests (by Chi-square ratios; p = 0.05) were run on Okanagan Lake stations to
determine validity within lake groupings. The results indicated combinations of
northern (N,W,C), central (K,M,P) and southern (H,S) - (see Figure 3.4), gave the
best representation of the varying trophic areas within Okanagan Lake.
(c) Skaha Lake
Although there were not large differences in total catch between north and
south stations in Skaha Lake, catches of rainbow trout, largescale sucker and
squawfish were higher in the north while in the south there was a greater pre-
ponderance of mountain whitefish and lake whitefish (Table 7.15). Relative abun-
dance of species was significantly different between the two stations.
7.6.2 Comparisons of Selected Fish Population Parameters Amongst Lakes
Throughout previous chapters, attempts have been made to discuss the data
from each lake individually and avoid between-lake comparisons wherever possible
during presentation of results. However, fishes - being summators of trophic
level as discussed previously, have a vast number of variables acting upon them -
thus the level of sensitivity in the culminatory role is much lower. It was there
fore decided that results from this program could be most meaningfully discussed
TABLE 7.15
NUMBER OF FISH TAKEN IN COMBINED SPRING. SUMMER AND AUTUMN (STANDARD) NET SETS AT DESIGNATED
STATIONS IN KALAMALKA, OKANAGAN AND SKAHA LAKES.
in a comparative or 'ranking amonst lakes' manner. With the above in mind, the
relative abundance of numbers and species, average length, weight-length relat-
ionship and growth rate are discussed.
(a) Total Catch
There were marked differences among lakes in the total number of fish
caught in the standard net sets (Figure 7.14). The lowest total catch was from
Wood Lake, followed by the catch noted at the south Kalamalka Lake station.
Catches at Kalamalka north station and at stations C and K in Okanagan Lake
were only slightly higher than those previously noted, while the highest
catches in Okanagan Lake itself came from the northerly and southerly stations
(Figure 7.14). Catches at both stations in Skaha Lake were among the highest in
the system, with the exception of Vaseux Lake. Catches in Skaha and Vaseux
Lakes were nearly double those from most of the other Okanagan main valley lake
stations. Catches in Osoyoos Lake were lower than those noted in Skaha or
Osoyoos Lakes, but were considerably higher than most from Okanagan Lake.
The seasonal distribution showed some variation in catch with summer
catches tending to be much lower than those in either spring or autumn. In
some cases, notably from central Okanagan stations, autumn catches far exceeded
those in spring and summer combined, chiefly because of the domination of
mature kokanee in the catch.
(b) Relative Catch
It is of ecological interest to compare the relative abundance of salmonids
(rainbow trout, kokanee and mountain whitefish) and coarse fish (castomids and
cyprinids) in the Okanagan main valley lakes. The highest and second highest
catches of salmonids invariably were taken in either Okanagan or Kalamalka
Lake, where the highest catches of coarse fish always came from Vaseux, Skaha
and Osoyoos Lake (Figure 7.15). Whitefish were scarce in catches from Wood or
Kalamalka Lakes, but in the other takes ranged from between to 8 to 25% of the
total catch. This trend of salmonids in Kalamalka and Okanagan Lakes and a
greater abundance of coarse fish in the lower lakes, applied also to catches
from each of the three seasons, even when considered separately.
It is informative to compare the relative abundance of species found in
the present study to that of data collected by Ferguson (1948) from Skaha Lake
in the summer of 1948 (Table 7.16). Chi-square analysis showed the difference
between years (1948 to 1971) to be highly significant even though data were
sparce. Numbers of mountain whitefish appear to be much lower in 1971 than in
1948. Also, no carp were taken in any of the lake net sets in 1948, although
several were caught by lake netting in 1971. The combined catch was somewhat
lower in 1971 than in 1948 (adjusted catches). Furthermore, the contribution
of salmonids to the catch was considerably lower in 1971 compared to 1948
(Table 7.16).
TOTAL CATCH OF FISH IN STANDARD GILL NET SETS AT
DESIGNATED STATIONS OF THE OKANAGAN MAIN VALLEY
LAKES. Figure 7.14
NUMBER OF FISH CAUGHT IN STANDARD NET SETS AT
DESIGNATED STATIONS OF THE OKANAGAN MAIN VALLEY
LAKES. Figure 7.15
TABLE 7.16
NUMBER OF FISH TAKEN IN STANDARD SUMMER NET SETS NEAR DESIGNATED
STATIONS IN SKAHA LAKE, 1948 and 1971.
TABLE 7.17
NUMBER OF
FISH TAKEN IN STANDARD SUMMER NET SETS NEAR DESIGNATED
STATIONS IN WOOD AND OKANAGAN LAKES. 1935 and 1971.
The data of Clemens et al (1939) from Wood and Okanagan Lakes affords
another interesting comparison of catch statistics over a 36 year period
(Table 7.17). There were marked differences in the relative abundance of fish
in Wood Lake between the two years. No carp were netted in the summer of 1935
(although they were in the lake) but 12 were caught in 1971. The contribution
of salmonids to the total catch in Wood Lake in each of the years was about
the same (Table 7.17).
More reliable comparisons of relative abundance are possible between 1935
and 1971 catches for Okanagan Lake. There appeared to be little difference in
total catch (combined stations) between the two years (Table 7.17). No carp
were netted in any of the stations in 1935, whereas single summer sets in 1971
took carp at three of the four 1971 stations shown (Table 7.17). Otherwise,
relative abundance between each of the stations for 1935 and 1971 were
similar. Apparently change in trophic structure has not yet affected the fish
populations in Okanagan Lake. This is to some extent borne out by the fact
that many of the eutrophication problems of Okanagan Lake are localized,
affecting mostly shoreline. areas.
(c) Length Analyses
There were differences in the average length of species captured when com-
parisons were made among the six main valley lakes. Rainbow trout, of the
same age, in Kalamalka Lake were significantly smaller than those from
Okanagan Lake, but not significantly smaller than those from Skaha or Osoyoos
Lakes. Kokanee from Wood and Kalamalka Lakes were significantly smaller than
those from any other lake in this system except Osoyoos Lake. Kokanee from
Skaha were the largest in the system. The average length of whitefish from
Okanagan Lake increased towards the south. Except for Vaseux Lake, a distinct
trend for increasing average length toward the south was evident in lake
whitefish from the basin lakes. Those from Skaha Lake were significantly
larger than any other, followed by Osoyoos Lake.
It is informative to compare length estimates of several species from
Skaha Lake between 1948 and 1971. Although few kokanee were netted in 1948,
even the largest of these did not attain the average length of those netted in
1971. Lake whitefish were also much larger in 1971 as were the largescale
suckers. It should be kept in mind that the sewage treatment plant at
Penticton did not commence operation until 1948, hence an increased rate of
eutrophication cannot be considered to be prevalent in this lake at the time
of the 1948 sampling. The increase in average size of these species between
1948 and 1971 is likely a real indication of the effects of lake enrichment by
sewage.
(d) Length-Weight Analyses
Wood Lake salmonids and coarse fish either had a lower weight-length regression
slope or were distinctly lighter in weight over most of the length range
considered (negative displacement). In no case did Wood Lake fish show
higher regression slopes or positive displacement compared with other lakes
(Figure 7.16). Weight-length regressions for Kalamalka Lake fish were either
lower than those in other lakes or showed no significant difference (Figure
7.16). Regressions for Okanagan Lake fish were the same or higher than
those for all lakes except Skaha. Fish from Skaha Lake generally had the
highest weight-length regression slope or positive displacement, lake
whitefish showed this most clearly (Figure 7.16). Species in Osoyoos Lake
showed the same trend as Okanagan Lake. Vaseux Lake fish tended to fall
below those for Okanagan, Skaha and Osoyoos Lakes.
Weight-length regressions for many Skaha Lake fish in 1971 had
significantly higher slopes or displacement than those in 1948. There has
been little or no change in weight-length regression for Okanagan Lake
rainbow trout between 1935 and 1971.
7.6.3 Summary
Based on the above data pertaining to fish population parameters, it
was possible to assess the present trophic state of the main valley lakes.
Although present data does not indicate a significant shift in species
composition, attributable to rapid eutrophication, such a change is
predicted if there is not a reversal in the current rate of
eutrophication, especially in Wood Lake.
Using a matrix canonical analysis to sort out various population
attributes for comparisons among lakes and using other information gathered
during the survey, it was possible to rank the lakes on an arbitrary trophic
scale. Most fisheries data indicated Skaha to be the most eutrophic lake
followed by Osoyoos and Vaseux Lakes. Kalamalka Lake was the least
eutrophic, with Okanagan Lake in an intermediate position. Wood Lake - in
terms of fish population parameters -ranked low, but evidence suggests that
it has reached this position after passing through a more eutrophic stage.
In other features discussed in earlier chapters, Wood Lake is considered
highly eutrophic.
TYPICAL WEIGHT-LENGTH REGRESSIONS FOR SELECTED
SPECIES OF FISH FROM THE OKANAGAN MAIN VALLEY
LAKES. Figure 7.16
CHAPTER 8 Nutrient Loading and the Trophic State
of the Main Valley Lakes. 8.1 GENERAL
The classic terms of Oligotrophic, mesotrophic and eutrophic are useful
for describing the character of lakes, but they do not allow quantitative
comparisons to be made. The rate at which nutrients enter a lake allows for
direct comparison among lakes from widely scattered geographical regions and
provides a more quantitative basis for evaluating the trophic state of lakes
(Vollenweider, 1969).
The total phosphorus load to each Okanagan main valley lake was considered
the most reliable indicator of current trophic state, for there was a strong
relationship between the concentrations of total phosphorus in lake water at
spring overturn and the amount of chlorophyll-a. in the photic zone in mid-
summer (Figure 8.1). This relationship of phosphorus load to lake primary
productivity will, in most cases, extend to alt trophic levels.
While total phosphorus load is a reliable trophic state indicator,
gathering valid data to use is by no means a simple task. The large volume of
most of the main valley lakes and the comparatively short length of the study
period further hampered the collection of precise data. The extreme
variations of tributary streamflows from year to year in the basin make any
single years' data questionable, if long term mean values are to be used in
planning. This is particularly the case in Okanagan Lake where values may
vary by a factor of several times annually (see Technical Supplement IV).
Several different approaches were used to gain an indication of phosphorus
loading rates to the main valley lakes. Actual field measurements were
obtained during the period 1969 to 1972. The length of time the various
sources were monitored varied. Streams and outfalls, the two major sources,
were monitored continuously. These data are presented in Table 8.1. A second
method used was based on theoretical soil characteristics and population-
dependent-phosphorus-export (Vollenweider, 1969), to calculate the total
phosphorus loads to all main valley lakes except Vaseux. As a check on this
method, the chemical nutrient data of Clarke and Alcock (1968) were used to
compute loads. A comparison of these data and other research data is
summarized in Table 8.2.
The data from actual measurement and that calculated according to
Vollenweider's
criteria were computed on an areal basis (gTP/m2) for the years of data and
plotted as a function of lake mean depth over water residence time (Figure
8.2). This provides a basis for determining the current trophic state of the
Okanagan main valley lakes.
TABLE 8.1
MAJOR NUTRIENT LOADINGS TO THE MAIN VALLEY LAKES
RELATION BETWEEN CHLOROPHYLL CONCENTRATION
AND TOTAL PHOSPHORUS CONTENT OF WATER FROM
THE OKANAGAN MAIN VALLEY LAKES.
Figure 8.1
TABLE 8.2
VALUES OF THE TOTAL PHOSPHORUS LOADINGS TO THE OKANAGAN LAKES AND OTHER PARAMETERS
OF IMPORTANCE IN THE CALCULATION OF THE TOTAL LOAD.*1
NOTE: The estimates shown in the above table, particularly that of Corrigan, Lerman, Stockner and Koshinsky, was based on early data interpretation, much of which was later revised. (See Table 8.1 and Technical Supplement IV).
In all cases (Figure 8.2) the values calculated are higher than those
estimated from study measurements. It is suggested that in this regard a
conservative approach, which means considering the maximums as perhaps a
high extreme, is most appropriate. With this attitude in mind, all the main
valley lakes are receiving phosphorus at excessive levels. Even using the
lower estimates, all main valley lakes - with the possible exception of
Kalamalka Lake - are receiving phosphorus inputs at or near dangerous
levels, thus unnaturally speeding the process of eutrophication.
8.2 NUTRIENT SOURCES
8.2.1 Osoyoos Lake
Almost 60 percent of the total annual phosphorus load comes from the
Okanagan River which drains Skaha and Vaseux Lakes above. Only about 30-35%
of the river load comes from Skaha or Vaseux Lakes, while the remainder
apparently comes from surface and sub-surface agricultural return flows and
from septic tanks located near the river. The Oliver Sewage Treatment Plant
contributes about 1,500 to 2,000 kg/year to Osoyoos Lake. Present evidence
indicates that the remainder comes from sub-surface flows from agricultural
lands and septic tank fields surrounding the lake. Hence, a large part of
the load to Osoyoos Lake is from sources which are difficult to control.
8.2.2 Vaseux Lake
The average total phosphorus load comes from the Okanagan River which
drains Skaha Lake above. Any reduction of phosphorus load in Skaha Lake
will accordingly reduce loads to Vaseux Lake, and as such represents the
only feasible means of nutrient control for this lake.
8.2.3 Skaha Lake
The average annual total phosphorus load to Skaha Lake is about 22,000
kg/year About 60 percent of this total comes from the Penticton Sewage
Treatment Plant and the remainder from the Okanagan River draining Okanagan
Lake, and from other surface and sub-surface flows to the south of the City
of Penticton.
8.2.4 Okanagan Lake
The average annual phosphorus load to Okanagan Lake is 85,000
kg/year. About 45% of this total is attributable to sewage treatment
plant effluent; 35% to tributary streams draining a variety of
landuse regions; and the balance to septic tanks (6%), dustfall and
precipitation (10%), and other sources (3%).
8.2.5 Kalamalka Lake
The average annual load to Kalamalka Lake is about 2,500 kg/year. No in-
dustrial or municipal outfalls enter this lake. The majority of the phosphorus
THE ANNUAL TOTAL PHOSPHORUS LOAD TO THE MAIN VALLEY LAKES OF
THE OKANAGAN BASIN, 1969-1971. Figure 8.2
load is from Coldstream Creek and sub-surface return flows. About 20% of
the total phosphorus load comes from Wood Lake, which has a small inflow
to the lake in the south basin.
8.2.6 Wood Lake
The average annual load to Wood Lake is about 1,500 kg/year. Recent
estimates indicate that about 25% of this total comes from Vernon Creek,
while the remainder comes from sub-surface return flows from septic tanks
(50%) and from agricultural lands (20%), which represent the predominant
landuse practice on the watershed. Two fruit packing plants with
outfalls discharging to the lake also contribute a small amount of
phosphorus to this lake.
CHAPTER 9 Establishment of Loading Criteria for the
Okanagan Main Valley Lakes.
9.1 STANDARDS AND BENEFITS FOR THE CONTROL OF ALGAL AND OTHER AQUATIC
PLANT GROWTH IN THE MAIN VALLEY LAKES
To provide a basis for projecting the effect of nutrient loadings on
each of the main valley lakes over the next 50 years, the maximum
desirable concentration of phosphorus in each lake at spring overturn has
been related to lake water quality and annual phosphorus loadings. Thus,
tentative standards are provided for the control of algal and aquatic
plant growth in each of the main valley lakes.
9.2 ROLE OF NUTRIENTS IN BIOLOGICAL PRODUCTION
Photosynthetic plants require light and a number of elements for their
maintenance and reproduction. The more important requirements are carbon
(C), hydrogen (H), oxygen (0) and nitrogen (N), since these elements make up
the predominant mass of cellular substance. Of most interest however, are
the essential elements that limit plant (algal) growth when in short supply.
Present and past studies indicate overwhelmingly that phosphorus (P) and
nitrogen (N) are of particular importance in lakes. Phosphorus is
considered to be the more easily controlled element in north temperate
lakes, for the following reasons:
1. The element nitrogen accounts for approximately 75% of our atmosphere by weight, whereas the element phosphorus is a trace element accounting for less than .1% of the earth's composition. The control of the element nitrogen would therefore appear to be far more difficult than the control of trace elements such as phosphorus.
2. Certain bacteria and algae are capable of obtaining their nitrogen requirements directly from the atmosphere by the process of nitrogen fixation. Limiting nitrogen therefore, would not control the growth of these organisms. Nitrogen fixing algae are one of the main types which have produced nuisance blooms in the Okanagan lakes.
3. Nitrogen is considered a transient element which travels readily through a soil column to groundwater and eventually to surface waters. Conversely, phosphorus is readily bonded into a soil column and leaching or movement of this element occurs only when the amount of phosphorus exceeds the bonding capability of the soil.
4. Invasion of atmospheric nitrogen is constantly occurring in lakes at the air-water interface.
While the control of phosphorus is currently considered to be the most
feasible method of controlling biological productivity in a lake, other
elements and compounds may still cause specific problems if amounts exceed
certain levels. Mercury and the pesticide DDT are two materials which have
adversely affected certain Okanagan lakes. Mercury levels in fish,
particularly trout, have reached levels in Kalamalka and Okanagan Lakes
which are affecting the reproductive capability of this species. High DDT
levels have apparently been detrimental to certain animal communities
within a lake, while allowing other less desirable species to flourish.
The effect of all elements must therefore be considered in assessing the
condition of a lake as well as the overall biological productivity that the
control of phosphorus may provide.
9.3 PHOSPHORUS FORMS AND BUDGETS
Phosphorus compounds in water are normally classified on the basis of
separation techniques. Data reported in these investigations are presented
as "orthophosphates" (P04) and "total phosphorus (TP). Total phosphorus is
a measure of all the phosphorus in the water whether in a soluble form or
contained in plant and animal cellular matter (insoluble). Orthophosphorus
is that portion of total phosphorus which is in a soluble form and
immediately available to plant life for synthesis (Table 9.1). While it
would have been desirable to use orthophorphorus to establish criteria for
acceptable lake loadings, this was not possible because of the following
factors:
1. In lakes, orthophosphorus is in a perpetual state of flux, with release or uptake occurring in minutes, and hence it is difficult to know what percentage of the available Orthophosphorus one is measuring at any given time.
2. The concentrations of phosphorus required for optimum growth vary with species and environmental conditions. In lakes, optimum growth may occur at levels below 0.01 milligrams per liter. This figure corresponds closely to the limit of available analytical procedures used in this study to measure phosphorus. In most instances, values of orthophosphorus in the lakes and streams discharging into the Okanagan lakes were below this level of sensitivity. Total phosphorus has therefore been used as an indicator of the biological productivity of each lake, and has been used to establish loading criteria which may achieve, within limits, an optimum level of biological production for multiple water use.
In some of the lakes there is presently an overabundance of phosphorus
(Chapter 7.1, 8) and other nutrients such as nitrogen are actually
limiting biological production. In these cases however, phosphorus is
still considered the key element and measures must be taken to reduce the
supply of phosphorus to these lakes to levels where it again exerts a
controlling influence on plant (algal) growth.
TABLE 9.1
FORMS OF PHOSPHORUS PRESENT IN SURFACE AND WASTEWATERS
9.4 CRITERIA FOR PHOSPHORUS LOADINGS
The 'assimilative capacity' of a lake may be defined as the percent of
total energy intake required for the growth, respiration and reproduction
of plant life. This relationship may be expressed as:
Nutrients required for plant growth,
Assimilative Capacity = respiration and reproduction/t
Total Nutrient Input/t
Where t = times in years.
For each nutrient, trace element and organic factor required for plant
growth, there is a relationship between supply and demand that can be
expressed by the assimilative capacity. In oligotrophic lakes, the
nutrient supply is so low that the input limits plant populations and
seasonal growth is balance by loss. In these cases, the input is equal to
the amount required to sustain existing plant life and the assimilative
capacity approaches 1. In eutrophic lakes, supplies of must nutrients are
in excess of demand and values of the assimilative capacity are less than
1. In these cases, factors such as available light, competition or
predation often limit growth to a greater extent than available nutrient
supply. Wood Lake is an excellent example of this condition, where
phosphorus is super-abundant and other nutrients, or the above mentioned
controls, regulate plant populations before the external supply is
exhausted. Unfortunately this type of control is not imposed until
nuisance levels of algal blooms and weed growth have been reached.
By limiting annual loadings of phosphorus to a lake to that which can be
assimilated within an acceptable level of biological production, high water
quality can be maintained and future quality predicted, based on annual
loadings. This approach has been used in establishing acceptable loading
objectives for each of the main valley lakes. Since each lake will respond
differently to a given nutrient load because of differences in mean depth,
water renewal rates and other factors, these loading objectives will vary from
lake to lake.
Values were set so as to achieve, within limits, an optimum level of
biological production for multiple water use without the occurrence of
nuisance algal blooms and extensive aquatic plant growth (Figure 9.1). These
objectives apply primarily to macro-sources of nutrients and the lake as a
whole, rather than to localized micro-sources of nutrients.
The values selected were based on information gained over the period 1969 to
1972, including the following:
1. Current average load of total phosphorus to each lake. 2. Present mean concentration of total phosphorus and orthophosphorus
at spring overturn. 3. The sediment retention of phosphorus and internal loading where
applicable. 4. Average algal biomass based on chlorophyll-a. determinations 5. Average biomass of zoobenthos and Zooplankton in relation to 1 and 4
above. The present (1970) average concentrations of phosphorus at spring
overturn, and suggested objectives for multiple water use are shown in Table
9.2. The rationale for establishing specific objectives for each of the main
valley lakes is summarized below:
9.4.1 Okanagan Lake
Because certain areas of this lake exhibit eutrophic characteristics while
the main body of the lake is oligotrophic, Okanagan Lake has been considered as
three separate basins and loading objectives computed for each section. It
should be recognized that this separation is not based on the natural state, but
was introduced to facilitate water quality evaluations for this lake.
(a) North Basin
Loading objectives for this basin were set at 55,000 to 75,000 pounds of
phosphorus per year. These loadings were considered to be approximately equal
to the assimilative capacity of existing plant biomass in the central portion
of the basin, which still exhibits excellent water quality. A loading of
66,000 pounds per year should be considered the maximum, recognizing that in
any given year the load may reach 75,000 pounds due to uncontrollable sources
of phosphorus. These values apply to the entire north basin and should not be
confused with point source loadings to small regions which may exhibit local
effects of nutrient enrichment. The shallow North and Vernon Arms will
continue to exhibit some aquatic
TABLE 9.2
TOTAL PHOSPHORUS CONCENTRATIONS AND LOADING CRITERIA - MAIN VALLEY LAKES
plant growth due to basin characteristics and continuing diffuse loadings
from the Armstrong and Vernon areas respectively.
(b) Central Basin
Objectives for the central basin are the same as for the north basin
and the same comments apply. Localized problems are expected to continue
along the Kelowna foreshore.
(c) South Basin
Values for this basin have been set lower than the previous two basins
so that this relatively large section of Okanagan Lake can act as a buffer
for lakes below. Positive point sources are few in this section of the lake
and the very large volume of excellent quality water should protect Penticton
beaches from any nuisance aquatic plant growths and insure a low nutrient
discharge from Okanagan Lake to Skaha Lake. Any proposed point sources
should be kept out of this basin to maintain a sizeable reservoir of good
quality water between Kelowna and the lake outlet at Penticton. A loading of
35,000 pounds per year should be considered an absolute maximum, again
recognizing that values below this will further ensure the maintenance of
good water quality.
9.4.2 Skaha Lake
Proposed criteria of phosphorus loadings to Skaha Lake range from 30,000
to 40,000 pounds per year. These somewhat high values take into account the
very short retention time of water in this lake (one year) and the excellent
source of good quality water flowing into the lake from Okanagan Lake.
If values remain within these established limits, good water quality
should be achieved. Sporadic algal blooms may continue to occur along with
moderate aquatic plant growth on the eastern shoreline, however the annual
occurrence of heavy blue-green blooms should be eliminated.
9.4.3 Osoyoos Lake
Phosphorus loading criteria established for this lake range from 26,000
to 37,000 pounds per year. These values allow for the very rapid water
renewal rate (residence time) which prevents the accumulation of large
amounts of nutrients. The maintenance of phosphorus loads below 37,000
pounds per year should prevent extensive algal blooms and control aquatic
plant growth to within manageable limits. Osoyoos Lake is largely dependent
on the quality of water in Skaha Lake and in Okanagan River, and improvement
in the quality of these lake and river waters will also benefit Osoyoos Lake.
9.4.4 Kalamalka Lake
Loading objectives for Kalamalka Lake range from 6,600 to 8,800 pounds per year.
This is much lower than for the other lakes because of the small volume
of inflow and the long retention time of water in this lake. Its calcium
carbonate cycle may partially buffer it from nutrient overload, but any large
increase in phosphorus loadings may cause this carbonate system to collapse.
The lake is already an effective plankton producer as evidenced in bioassay
studies, and recent paleolimnological investigations. If phosphorus loadings
can be curtailed to within these proposed limits, the lake should maintain
its present excellent condition.
9.4.5 Wood Lake
The loading objectives set for Wood Lake are 2,000 to 3,000 pounds of
phosphorus per year. These annual rates are no doubt above historical, but
below present levels. If the objectives are met and a continual source of
good quality water reaches this lake, the occurrence of annual blue-green
algal problems should be eliminated as well as the need for periodic aquatic
plant harvest. The lake will continue to be a productive lake, but not in
the sense of objectionable nuisance organisms. Clarity and oxygen levels
will be improved and sport fisheries rejuvenated if these objectives are met.
Because of the existing high internal loading of phosphorus to this lake, a
significant decrease in phosphorus loadings will be required initially to
affect any change in its condition. The lower loading objective of 2,000
pounds should therefore be used until a significant improvement in the water
quality of Wood Lake has been achieved.
The higher inflows and reduced retention time of water in this lake due
to industrial cooling water discharges, should speed the recovery of the
lake, but will have no immediate effect on its water quality.
9.4.6 Vaseux Lake
Proposed objectives for this lake range between 17,500 and 22,000 pounds
of phosphorus per year. The achievement of these objectives depends
primarily on improving the quality of Skaha Lake and Okanagan River water.
Extensive aquatic plant growth will always be an integral part of this lake
due to its shallowness and rich bottom sediments. This habitat is considered
suitable for this lake as it has been established as a wildlife sanctuary.
9.5 COSTS AND BENEFITS ASSOCIATED WITH LAKE MATER QUALITY
The costs associated with lake water quality maintenance and/or
improvement involve the expenses incurred with the construction of waste
treatment facilities which reduce nutrient contributions. These costs are
dealt with at length in Technical Supplement VI.
The benefits of water quality involve evaluation of many social and
economic values; i.e. beach recreation, aesthetics, beach oriented tourist
expenditures. These benefits are explained and evaluated in relation to water
quality control in Technical Supplement VIII.
MAP SECTION
FILE of OKANAGAN MAIN VALLEY LAKES Ma
The Di
and th
Plankt
Skaha
11,196
Kalama
25,197
Drawn By: G.S.Mc Nov
CHA
SOME LIMNOLOGICAL CHARACTERISTICS OF VASEUX LAKE
Map 4
SOME
LIMNOLOG
CHARACTE
OF SKAHA
SOME LIMNOLOGICAL
CHARACTERISTICS
OF THE SOUTHERN
SECTION OF
OKANAGAN LAKE
Map 6
SOME LIMNOLOG
CHARACTERISTI
THE NORTHERN
OF OKANAGAN L
SOME LIMNOLOGICAL
CHARACTERISTICS OF
KALAMALKA LAKE
Map 9
SOME LIMNOLOGICAL CHARACTERISTICS OF WOOD LAKE
Map 10
ACKNOWLEDGEMENTS
The authors in this case had the task of compiling into an overall
format, all the field studies pertaining to limnology which were part of
the Okanagan Basin Study. Thus, most of the original work and data is
that of other investigators. The major manuscript reports used in this
compilation are listed in a section of the References portion of the
supplement.
This supplement could not have been compiled without the
cooperation, support and hard work of all involved in the Okanagan Basin
study limnology program as well as the Study Office staff in Penticton.
The assistance of those listed below as well as many others too numerous
to mention, is here most gratefully acknowledged.
Freshwater Institute - Fisheries Research Board of Canada
Dr. K. Patalas Mr. A. Saiki Dr. 0. Saether Miss M. McLean Mr. G.D. Koshinsky* Mr. G. Girman Mr. R. Robarts Mr. P. Findlay Mr. B. Carney
Canada Centre for Inland Waters
Dr. J. Blanton Mr. H. Ng Dr. B. St. John Mr. D. Williams Dr. A. Lerman*
B.C. Fish and Wildlife Branch
Dr. T.G. Northcote*
Mr. T.G. Halsey Mr. S.J. MacDonald
Okanagan Basin Study Office
Mr. A. Murray Thomson Mr. G. McKenzie
*Affiliation shown is for the period 1969-72.
REFERENCES
REFERENCES A. MANUSCRIPT REPORTS
Manuscript reports prepared as part of the Canada-British Columbia
Okanagan Basin Agreement study which were used extensively in the
preparation of Technical Supplement V
Blanton, J.O. 1972, Relationships Between Heat Bontent and Thermal Structure in the Mainstem Lakes of the Okanagan Valley, British Columbia, 17pp
Blanton, J.O., and H.Y.F. Ng. 1971. Okanagan Basin Studies; Data Report on the Fall Survey, 1970. 125pp.
Blanton, J.O., and H.Y.F. Ng. 1972. The Physical Limnology of the Mainstem Lakes in the Okanagan Basin, 2 Volumes, 34pp, 24 figures, 2 appendices.
Blanton, J.O., and H.Y.F. Ng. 1972. The Circulation of the Effluent from the Okanagan River as it enters Skaha Lake. 23pp.
Lerman, A. 1972. Chemical Limnology of the Major Lakes in the Okanagan Basin:
Nutrient Budgets at Present and in the Future. 41pp.
Northcote, T.G., T.G. Halsey and S.J. MacDonald. 1972. Fish as Indicators of
Water Quality in the Okanagan Basin Lakes, British Columbia. 80pp.
Patalas, K and A. Saiki, 1973. Crustacean Plankton and the Eutrophication of Lakes in the Okanagan Valley, British Columbia. 34pp.
Saether, O.A., and M.P. McLean. 1972. A Survey of the Bottom Fauna in Wood,
Kalamalka and Skaha Lakes in the Okanagan Valley, British Columbia. 20pp
St. John, B.E. 1972. The Limnogeology of the Okanagan Mainstem Lakes, 46 pp.
Stockner, J.G. 1971. Preliminary Evaluation; Water Quality, 4pp.
1972. Diatom Succession in the Recent Sediments of Skaha Lake,
British Columbia. 17pp. 1972. Nutrient Loadings and Lake Management Alternatives. 13pp.
Stockner, N.J., G.R. Girman and R.D. Roberts. 1972. Algal Nutrient Addition and Pure Culture Bioassay Studies on Six Lakes in the Okanagan Basin, British Columbia. 52pp.
Stockner, J.G., M. Pomeroy, W. Carney and D.L. Findlay. 1972. Studies of Periphyton in Lakes of the Okanagan Valley, British Columbia. 19pp.
Stockner, J.G., W. Carney and G. McKenzie. 1972. Task 122: Phytobenthos, Littoral Mapping Supplement. 10pp. 16 plates
Williams, D.J. 1972. General Limnology of the Mainstem Lakes in the Okanagan Valley, British Columbia. 12pp.
REFERENCES
(Continued)
B. CITED LITERATURE
Alcock, F.R., and D.A. Clarke. MS 1968. Report to Pollution Control Board, South Okanagan Health Unit. 1-13.
American Public Health Association. 1965. Methods for the Examination of Water and Wastewater, 12th Ed., APHA, New York.
Anderson, T.W. 1972. Historical Evidence of Land Use in Pollen Stratigraphies from Okanagan Mainstem Lakes, B.C.; in preparation
Armstrong, F.A.J. and D.W. Schindler. 1971. Preliminary Chemical Characterization of Maters in the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. Canada 28: 171-187.
Armstrong, J.E., D.R. Crandell, D.J. Easterbrook, and J.B. Noble. 1965. Late Pleistocene Stratigraphy and Chronology in Southwestern British Columbia and Western Washington: Geol. Soc. Am. Bull., v.79; 321-330
Booth, D.M., T.J. Coulthard and J.R. Stein. 1969. Water Quality Deterioration in Osoyoos Lake, British Columbia: Paper presented at CSAE Annual Meeting, Saskatoon; August 24-28, 1969.
Burton, W. and J.F. Flannagan. In press. An improved Ekman-type garb.
Cairnes, C.E. 1932. Mineral Resources of Northern Okanagan Valley, British Columbia: Geol.Surv. Canada, Sum. Rept. 1931: Pt A, pp 66-109.
Cairnes, C.E. 1937. Kettle River Map Area, West Half, British Columbia: Geol. Surv. Canada; Paper 37-21.
Cairnes, C.E. 1939. The Shuswap Rocks of Southern British Columbia: Proc. Sixth Pacific Science Congress, Vol. I, pp. 259-272.
Clarke, D.A., South Okanagan Health Unit: Submarine Photometry Study, 1972.
Clemens, W.A., D.S. Rawson and J.L. McHugh. 1939. A biological survey of Okanagan Lake, British Columbia. Fish. Res. Bd., Canada; Bull. 56: 70p
Cleve-Euler, A. 1971. Die Deatomeen von Schewedn und Funnland. Almquist and Wiksells Boktrycheri, Stockholm, Sweden. 1171p
Coulthard, T.L., and J.R. Stein. 1969. Water Quality Deterioration in Osoyoos Lake, British Columbia. Unpublished report for Water Investigations Branch, B.C. Water Resources Service.
Daly, R.A. 1912. North American Cordillera, Forty-ninth Parallel: Geol. Surv. Canada. Mem. 38. Pts. 1, 2 and 3; 1912.
Dawson, G.M. 1878. Explorations in British Columbia: Geol. Surv. Canada, Rept. Prog. 1876-77: pp 16-149.
Dawson, G.M. 1879. Preliminary Report of the Physical and Geological Features of the Southern Portion of the Interior of British Columbia: Geol. Surv. Canada. Rept. of Prog. 1877-78; pp. 96B-101B.
Dobson, H. 1972. Nutrients in Lake Huron (unpublished manuscript. C.C.I.W., Burlington, Ontario).
Ferguson, R.G. 1949. The Interrelations Among the Fish Populations of Skaha
Lake, B.C., and their Significance in the Production of Kamloops Trout (Salmo gairdnerii kamloops jordan). B.A. thesis, Dept. Zool., Univ. Brit. Col., 84 pp. + 6 appendices.
Flannagan, J.F. 1970. Efficiencies of Various Grabs and Corers in Sampling Freshwater Benthos. J. Fish. Res. Bd. , Canada, 27: 1691=1700.
Flint, R.F. 1935a. Glacial Features of the Southern Okanagan: Geol. Soc.. Amer. Bull., Vol: 46; pp 169-193
Flint, R.F. 1935b. White Silt: Deposits in the Okanagan Valley, B.C.: Roy. Soc. Canada, Trans., Series 3. Vol. 29; Sec. 4.
Fulton, R.J. 1965. Silt Deposition in Late-Glacial Lakes of Southern British Columbia: Am. J. Sci., Vol 263; p 553-570
Fulton, R.J. 1969. Glacial Lake History, Southern Interior Plateau, British Columbia: Geol. Surv. Can., Paper 69-37; 14pp.
Grove, P.C. (ed), 1965. Webster's Third New International Dictionary. Merriam & Co., Springfield, Mass. 2662pp.
Hansen, H.P. 1955. Post-Glacial Forests in South Central and Central British Columbia: Am. J. Sci. , Vol 253; No. 11, p 640
Holland, S.S. 1964. Land Forms of British Columbia, a Physiographic Outline: B.C. Dept. Mines and Petroleum Resources Bull. No. 48; 138pp.
Hustedt, F. 1930. Bacillariophyta (Diatomeae), p. 1-466. In A. Pascher (ed.). Die Susswasserflora Mitteleuropas, Bd. 10. Gustave Fisher, Jena.
Hutchinson, G.E. 1957. A Treatise on Limnology, Vol. I; Geography, Physics and Chemistry. John Wiley and Sons Inc., New York; 1015p.
Hyndman, D.W. 1968. Med-Mesozoic Multiphase folding along the Border of the Shuswap Metamorphic Complex: Bull. Geol. Soc. Am., Vol 79; pp 575-588.
Jones, A.G. 1959. Vernon Map-Area, British Columbia: Geol. Surv. Can. Mem. 296.
Kelley, C.C., and R.H. Spilsbury. 1949. Soil Surve of the Okanagan and Similkameen Valley, British Columbia. Rept. 3 of B.C. Survey. The B.C. Dept. Agriculture in cooperation with Experimental Farms Service, Dominion Dept. of Agriculture: 1-88.
Kemp, A.L.W. 1971. Organic Carbon and Nitrogen in the Surface sediments of Lake Ontario, Erie and Huron: J. Sed. Pet.. Vol 41; No. 2, p 537-548.
Larkin, P.A. and T.G. Northcote. 1969. Fish as Indices of Eutrophication, p 256-273 in: Eutrophication: Causes, Consequences, Correctives. Nat. Acad. Sci ., Washington, D.C.
Liebman, H. 1960. Handbuch der Frischwasser und Abwasser-Biologie. Biologie des Trinkwassers, Badewassers, Tischwassers, Vorftuters und Abwasser. II R. Oldenbourg, Munchen, 1149 -.
Livingstone, D.A. 1963. Chemical Composition of Rivers and Lakes. Data of Geochemistry, 6th ed. Chapt. G.; Geological Survey Professional Paper 440-G. Govt. Printing Office, Washington 25, D.C. 61pp.
Mackereth, F.J.M. 1969. A short core sampler for subaqueous deposits. Limnol. & Oceanogr. 14: 145-151.
McHugh, J.L. 1936. The Whitefishes (Coregonus clupeaforms [Mitchill], and Propsopium Williamsoni [Girard] of the Lakes of the Okanagan Valley, B.C. B.A. thesis, Dept. Zool . , Univ. Brit. Col., 84- + 5 figures, 22 plates.
Mathews, W.H. 1944. Clacial Lakes and Ice Retreat in South Central British Columbia: Roy. Soc. Canada, Trans. Vol. 38; Sec. 4, pp 39-57.
Meyer, C. and K. Yenne, 1940. Notes on the Mineral Assemblage of the "White Silt" Terraces in the Okanagan Valley, British Columbia: J. Sed. Petrology: Vol. 10; No. 1, pp 8-11.
Nasmith, H. 1962. Late Glacial History and Surficial Deposits of the Okanagan Valley, British Columbia: B.C. Dept. Mines and Petroleum Resources Bull. 46; 46p.
Nicholson, H.F. 1970. The Chlorophyll-a Content of the Surface Waters of Lake Ontario, June to November, 1967. Fish. Res. Bd. of Canada. Techn. Rept. No. 186; 31pp.
Northcote, T.G. and P.A. Larkin. 1956. Indices of Productivity in British Columbia Lakes. British Columbia Game Commission & University of British Columbia; Vancouver. J. Fish. Res. Bd. Canada 13 (4), pp 515-540.
Papp, 1969. Provisional Algal Assay Procedure, Joint Industry/Government Task Force on Eutrophication. P.O. Box 3011, Grand Central Station, New York, N.Y. 10017; 62p.
Patrick. R. and E.W. Reimer. 1966. The Diatoms of the United States; Vol. 1, Monogr. Acad. Natur. Sci., Phila. 13: 688p.
Reineike, L. 1915. Physiography of Beaverdell Area: Geol. Surv. Canada, Mus. Bull. No. 11 .
Rigg, G.B. and H.R. Goud. 1957. Age of Glacier Peak Eruption and Chronology of Post-Glacial Peat Deposits in Washington and Surrounding Areas: Am. J. Sci.; Vol. 255. pp 341-363.
Saether, O.A. 1970. A Survey of the Bottom Fauna in Lakes of the Okanagan Valley, British Columbia. Techn. Rep. Fish Res. Bd. Canada; 196. 1-26 and 1-17
Sakamoto, M., 1971. Chemical Factors Involved in the Control of Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. Canada 28: 203-213
Schindler. D.W. and S.K. Holmgren, 1971. Primary Production of Phytoplankton in the Experimental Lakes Area, Northwestern Ontario and Other Low-carbonate Waters, and a Liquid Scintillation Method for Determining C Activity in Photosynthesis. J. Fish. Res. Bd. Canada 28: 189-301.
Shah, R., J.K. Syers, J.D.H. Williams and T.W. Walker, 1968. The Forms of Inorganic Phosphorus Extracted from Solids by N Sulfuric Acid: N.Z. Journal of Agricultural Res., Vol. 11; No. 1, 184-192.
Sismey, E.D. 1921. A Contribution to the Algae Flora of the Okanagan (British Columbia). Canadian Field Nature. 35: 112-114
Sladeckova, A. 1963. Aquatic Deuteromycetes as Indicators of Starch Campaign Pollution. Intern. Rev. Hydrobiol. 48: 35-42.
Stein, J.R., and T.L. Coulthard, 1971. Water Quality Deterioration in Osoyoos Lake, British Columbia. Unpublished report for Water Investigations Branch, B.C. Water Resources Service.
Stockner, J.G. and F.A.J. Armstrong. 1971. Periphyton of the Experimental Lakes Area, Northwestern Ontario. J. Fish. Res. Bd. of Canada, 28: pp 215-229.
Stockner, J.G. and T.G. Northcote, 1974. (in press). Recent Limnological Studies of Okanagan Basin Lakes and their Contribution to Comprehensive Water Resource Planning.
Sverdrup, H.V., M.W. Johnson and R.H. Fleming, 1942. The Oceans; their Physics, Chemistry and General Biology. Prentice-Hall, Englewood Cliffs, N.J., U.S.A. 1098 pp.
Tipper, H.W. 1971. Glacial Geomorphology and Pleistocene History of Central British Columbia: Geol. Surv. Canada Bull: 196.
Vollenweider, R.A., 1969. Mogiichkeiten und Grenzen Elementarer Modelle der Stoffbitanz von Seen. Arch. Hydrobiol. 66: 1:1-36.
Westgate, J.A., D.G.W. Smaith and M. Tomlinson, 1970. Late Quaternary Tephra Layers in Southwestern Canada: In Early Man and Environments in Northwest North America: Univ. of Calgary Archaeol. Assoc., The Students Press; Calgary; pp 13-34.
Wilcox, R.E. 1965. Volcanic Ash Chronology: The Quaternary of the United States: H.E. Wright, Jr. and D.G. Frey (eds.), Princeton University Press, pp 807-816.
Williams, J.D.H., J.K. Syers, and T.W. Walker, 1967. Fractionation of Soil Inorganic Phosphorus by a Modification of Chang and Jackson's Procedure: Soil Science of America Proceedings: Vol 31; No. 6, 736-739pp.
Woodridge, C.G. 1940. The Boron Content of some Okanagan Soils: Sci. Agr. XX:5.
Wright, H.E., Jr. and D.G. Frey, (eds) 1965. The quaternary of the United States. University Press, Princeton University, New Jersey. pp922.
Yentsch, C.S. and D.W. Menzel. 1973. A Method for Determination of Phytoplankton Chlorophyll and Phaeophytin by Fluorescene. Deep See Res.; 10:
221-231.
APPENDICES
APPENDIX A
MAJOR LIMNOLOGICAL STUDIES AND RESPONSIBLE
PERSONNEL AND AGENCIES
APPENDIX A
MAJOR LIMNOLOGICAL STUDIES AND RESPONSIBLE PERSONNEL AND AGENCIES
APPENDIX B
GEOLIMNOLOGY RESULTS
B-l Sample Station Depths; Sample Colors; and Percentage
Gravel-Sand-Silt and Clay
B-2 Total Major Element Content of Samples from Okanagan
Main Valley Lakes
B-3 Acid-Extractable Major Elements and Total Mercury
Content of Samples from Okanagan Main Valley Lakes
B-4 Acid-Extractable Phosphorus in Samples from the Okanagan
Main Valley Lakes
B-5 Organic and Inorganic Carbon Content of Samples from
Okanagan Main Valley Lakes
B-6 Carbon Content of Sub-samples from Cores from Deepest
Points of Each of the Okanagan Main Valley Lakes
B-7 Diatom Succession in Cores from Skaha Lake
APPENDIX B-1
SAMPLE STATION DEPTHS: SAMPLE COLORS: AND PERCENTAGE
GRAVEL-SAND-SILT AND CLAY
APPENDIX B-l . . . CONTINUED
APPENDIX B-l . . . CONTINUED
APPENDIX B-2: TOTAL MAJOR ELEMENT CONTENT OF SAMPLES FROM OKANAGAN MAIN VALLEY LAKES
APPENDIX B-2 . . . CONTINUED
APPENDIX B-2 . . . CONTINUED
APPENDIX B-2 . . . CONTINUED
APPENDIX B-2 . . . CONTINUED
APPENDIX B-2 . . . CONTINUED
APPENDIX B-3
ACID-EXTRACTABLE MAJOR ELEMENTS AND TOTAL MERCURY CONTENT OF SAMPLES FROM
OKANAGAN MAIN VALLEY LAKES
APPENDIX B-3 . . . CONTINUED
APPENDIX B-5 . . . CONTINUED
APPENDIX B-5 . . . CONTINUED
APPENDIX B-4
ACID-EXTRACTABLE PHOSPHORUS IN SAMPLES FROM THE OKANAGAN MAIN VALLEY LAKES
(Parts per Million)
APPENDIX B-5
ORGANIC AND INORGANIC CARBON CONTENT OF SAMPLES FROM
OKANAGAN MAIN VALLEY LAKES
APPENDIX B-5 . . . CONTINUED
APPENDIX B-6
CARBON CONTENT OF SUBSAMPLES FROM CORES FROM DEEPEST POINTS OF
EACH OF THE OKANAGAN MAIN VALLEY LAKES
APPENDIX B-7
DIATOM SUCCESSION IN CORES FROM SKAHA LAKE
APPENDIX C
CHEMICAL LIMNOLOGY DATA FOR THE OKANAGAN MAIN VALLEY LAKES
C-l Data Listing of Nutrient Analyses for the Okanagan Main
Valley Lakes, 1971
C-2 Data Listing of the Major Cation Species for the Okanagan
Main Valley Lakes, 1971
C-3 Data Listing of the Major Anion Species for the Okanagan
Main Valley Lakes
APPENDIX C-l
DATA LISTING OF NUTRIENT ANALYSES FOR THE OKANAGAN MAIN VALLEY LAKES. 1971
(Parts Per Million)
APPENDIX C-l . . . CONTINUED
APPENDIX C-l . . . CONTINUED
APPENDIX C-2
DATA LISTING OF THE MAJOR CATION SPECIES FOR THE OKANAGAN MAIN VALLEY LAKES, 1971.
(Parts Per Million)
APPENDIX C-2 . . . CONTINUED
APPENDIX C-2 . . . CONTINUED
APPENDIX C-2 . . . CONTINUED
APPENDIX C-3
DATA LISTING OF THE MAJOR ANION SPECIES FOR THE OKANAGAN MAIN VALLEY LAKES
(Parts Per Million)
APPENDIX C-3 . . . CONTINUED
APPENDIX C-3 . . . CONTINUED
APPENDIX C-3 . . . CONTINUED
APPENDIX C-3 . . . CONTINUED
APPENDIX D
PHYSICAL LIMNOLOGY DATA
D-1 Parameters Used for Calculation of Hypolimnetic Areal Oxygen Deficits of
Lakes Skaha, Osoyoos and Wood.
D-2 Mean Concentrations of Oxygen in the Okanagan Main Valley Lakes
D-3 Daily Oxygen Depletion Rates, Areal Depletion Rates and Trophic Indices
for the Main Valley Lakes
D-4 Field Measurements for Temperature, Conductivity, Dissolved Oxygen and
pH for the Main Valley Lakes.
D-5 Period of Maximum Surface Temperatures, Summer Heat Incomes and
Transmission Values for Main Valley Lakes.
APPENDIX D-l
THE PARAMETERS USED FOR CALCULATION OF HYPOLIMNETIC AREAL OXYGEN DEFICIT OF LAKES SKAHA, OSOYOOS AND WOOD
APPENDIX D-2
MEAN CONCENTRATIONS OF OXYGEN IN THE OKANAGAN MAIN VALLEY LAKES, 1972
(Parts per million - Percent Saturation in Brackets)
APPENDIX D-3
DAILY OXYGEN DEPLETION RATES. AREAL DEPLETION RATES AND TROPHIC
INDICES FOR THE MAIN VALLEY LAKES, 1972
APPENDIX D-4
FIELD MEASUREMENTS FOR TEMPERATURE. CONDUCTIVITY. DISSOLVED OXYGEN AND pH FOR THE MAIN VALLEY LAKES.
APPENDIX D-4 . . . CONTINUED
APPENDIX D-4 . . . CONTINUED
FIELD MEASUREMENTS - KALAMALKA LAKE TEMPERATURE,
* pH recorded from samples in Kelowna Field Laboratory
* Turbidity recorded from sampler in Kelowna Field Laboratory
CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - KALAMALKA LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENT - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE TEMPERATURE,
CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OKANAGAN LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - SKAHA LAKE TEMPERATURE,
CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - SKAHA LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - SKAHA LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - SKAHA LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OSOYOOS LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OSOYOOS LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OSOYOOS LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
FIELD MEASUREMENTS - OSOYOOS LAKE
TEMPERATURE, CONDUCTIVITY, DISSOLVED OXYGEN AND pH
APPENDIX D-5
PERIOD OF MAXIMUM SURFACE TEMPERATURES, SUMMER HEAT INCOMES AND TRANSMISSION VALUES
FOR THE MAIN VALLEY LAKES, 1972
SURFACE TEMPERATURES
APPENDIX E
BIOASSAY PROGRAM
E-l Type, Station, Location and Duration of Experiments, 1970 and 1971 E-2 Ranking of Okanagan Lakes Based on Yield, Pure
Culture Bioassay Experiments, 1970. E-3 Ranking of Okanagan Lakes Based on Yield, Pure
Culture Bioassay Experiments, 1971.
APPENDIX E-l
BIOASSAY PROGRAM
TYPE, STATION, LOCATION AND DURATION OF EXPERIMENTS, 1970 and 1971
APPENDIX E-l . . . CONTINUED
APPENDIX E-1 . . . CONTINUED
APPENDIX E-2
RANKING OF OKANAGAN LAKES BASED ON YIELD. PURE CULTURE
BIOASSAY EXPERIMENTS, 1970
APPENDIX E-3
RANKING OF OKANAGAN LAKES BASED ON YIELD, PURE CULTURE BIOASSAY
EXPERIMENTS, 1971
APPENDIX F
CRUSTACEAN PLANKTON AND ASSOCIATED DATA
F-1 Lake Area, Littoral Area, Zooplankton Abundance and Average Number of
Zooplankton Crustaceans in the Main Valley Lakes.
F-2 Chemical Analysis of Water at One Water Depth for Main Valley Lakes,
1969 to 1971.
F-3 Species Composition of Crustacean Plankton in Okanagan Lake, 1969 and
1971
F-4 The Distribution of Species in the Upper 5 Meters of Inshore and
Offshore Water for Okanagan Lake, 1971
F-5 Species Composition of Crustacean Plankton in Skaha and Osoyoos Lakes,
1969 and 1971.
F-6 Some Limnological Characteristics and Parameters used for Calculation
of the Total Phosphorus Load to the Lakes of the Okanagan, According to
Vollenweider's Criteria (1968).
F-7 Comparison of Several Limnological Characteristics of Okanagan Valley
Lakes with Lakes Ontario, Mendota, and Washington.
F-8 List of Species Found in Net Plankton of Okanagan and Kalamalka Lake,
1935 to 1971.
F-9 Vertical and Horizontal Distribution of Temperature in Okanagan Lake,
September 1969 and August 1971.
F-10 Graphical Presentation of Horizontal Distribution of Secchi Disc Vis-
ibility, Dissolved Oxygen, Total Solids, Electrical Conductivity and
Calcium in Okanagan Lake in September 1969 and August 1971.
F-ll Graphical Presentation of Vertical Distribution of Temperature and
Dissolved Oxygen in the Okanagan Main Valley Lakes, September 1969 and
August 1971.
F-12 Graphical Presentation of Vertical Distribution of Zooplankton in
Okanagan Lake, September 1969
F-13 Graphical Presentation of Horizontal Distribution of Particular
Species of Zooplankton in Okanagan Lake, September 1969 and August
1971.
APPENDIX F-l LAKE AREA, LITTORAL AREA, AND PERCENT OF LAKE AREA
COMPRISED OF LITTORAL
ZOOPLANKTON ABUNDANCE IN THE OKANAGAN MAINSTEM LAKES
(Data of Patalas & Salki, 1972)
AVERAGE NUMBERS OF ZOOPLANKTONIC CRUSTACEANS IN THE GREAT LAKES AND
OKANAGAN BASIN LAKES (from Patalas 1972, Patalas and Salki 1972)
APPENDIX F-2
CHEMICAL ANALYSIS OF WATER FROM LAKES OKANAGAN, SKAHA, OSOYOOS,
WOOD AND KALAMALKA. SAMPLES TAKEN AT 1 m DEPTH
APPENDIX F-3
SPECIES COMPOSITION OF CRUSTAEAN PLANKTON (INDIVIDUALS PER CM2) IN LAKE OKANAGAN SEPTEMBER 9-10, 1969, AND AUGUST 24-26, 1971
(First row for station is 1969 data - second row for station is 1971 data)*
APPENDIX F-4
THE DISTRIBUTION OF SPECIES IN THE UPPER 5 m LAYER OF INSHORE
AND OFFSHORE WATERS OF LAKE OKANAGAN. AUGUST 25-26,1971 (indiv./l)
APPENDIX F-5 SPECIES COMPOSITION OF CRUSTACEAN PLANKTON (INDIVIDUALS PER CM2) IN LAKES SKAHA AND OSOYOOS,
ON SEPTEMBER 11. 1969 AND AUGUST 24. 1971 AND IN LAKES WOOD AND KALAMALKA ON AUGUST 26, 1971
(First row for station is 1969 data - second row for station is 1971 data)*
APPENDIX F-6 SOME LIMNOLOGICAL CHARACTERISTICS AND PARAMETERS USED FOR CALCULATION OF THE TOTAL PHOSPHORUS LOAD TO
THE LAKES OF THE OKANAGAN VALLEY ACCORDING TO VOLLEHWEIDER'S CRITERIA (1968).
NOTES: Morphometric data of the lakes taken from the bathymetric mpas prepared by the Fish and Wildlife Branch, Dept. of Recreation and Conservation in 1966 (J.A. Balkwill).
Area of the drainage basin according to Coulthard and Stein (1967). Discharge from Alcock and Clarke (1968). Populations estimated 1850-1990 according to Government of British Columbia (1971). Phosphorus retention (R) estimates based on Vollenwieder (1968). Predicted P load estimates in 1990 based on the assumptions: a) no phosphorus removal; b) 80 per cent phosphorus removed in controllable sources.
APPENDIX F-7
A COMPARISON OF SEVERAL LIMNOLOGICAL CHARACTERISTICS OF LAKES OF OKANAGAN VALLEY, AND LAKES ONTARIO,
MENDOTA AND WASHINGTON, LAKE MEANS, EXCEPT WHERE INDICATED. 1935 and 1936 DATA TAKEN FROM RAWSON (1939).
APPENDIX F-8
List of species found in net plankton of Lakes Okanagan and Kalamalka in the
period from 1935 to 1971. (1935 data taken from Rawson (1939),
identifications by Dr. G.C. Carl; 1951 data, identifications by present
authors from samples kindly provided by Dr. T.G. Northcote). (from Patalas
and Salki, 1972).
APPENDIX F.9
APPENDIX F.1O
APPENDIX F.11
APPENDIX F.12
APPENDIX F.13
APPENDIX G
BENTHIC (BOTTOM) FAUNA DATA
G-l Average Numbers of Bottom Organisms per Square Meter for Main
Valley Lakes, 1935, 1969 and 1971.
G-2 Number of Specimens Collected per Sample in Okanagan, Skaha and
Osoyoos Lakes (1969).
G-3 Number of Specimens Collected per Triplicate Sample in Wood,
Kalamalka and Skaha Lakes, 1971.
G-4 Pictoral Presentation of Degree of Enrichment as Indicated by
Distribution of Oligochaeta and Chironomidae in Main Valley
Lakes. 1969 and 1971.
APPENDIX G-l
AVERAGE NUMBER OF BOTTOM ORGANISMS PER SQUARE METER FOR THE
MAIN VALLEY LAKES, 1936, 1969 and 1971.
APPENDIX G-l . . . CONTINUED
APPENDIX G-l . . . CONTINUED
THE AVERAGE NUMBER OF BOTTOM ORGANISMS PER M2 IN WOOD, KALAMALKA AND SKAHA LAKES
APPENDIX G-2
NUMBER OF SPECIMENS COLLECTED PER SAMPLE IN OKANAGAN, SKAHA AND OSOYOOS LAKES
(1969) (Stations 1 to 42)
APPENDIX G-2 . . . CONTINUED
APPENDIX G-2 . . . CONTINUED
APPENDIX G-2 . . . CONTINUED
APPENDIX G-2 . . . CONTINUED
APPENDIX G-3
NUMBER OF SPECIMENS COLLECTED IN TRIPLICATE SAMPLES (675CM2)
IN WOOD, KALAMALKA AND SKAHA LAKES, (1971)
APPENDIX G-3 . . . CONTINUED
APPENDIX G-3 . . . CONTINUED
APPENDIX G-4
PICTORIAL PRESENTATION OF DEGREE OF ENRICHMENT AS INDICATED BY
DISTRIBUTION OF OLIGOCAETA AND CHIRONOMIDAE IN MAIN
VALLEY LAKES, 1969 and 1971
APPENDIX G-4 . . . CONTINUED
APPENDIX G-4 . . . CONTINUED
APPENDIX G-4 . . . CONTINUED
APPENDIX H
PERIPHYTON
Phosphorus, Nitrogen and Carbon Content
of Periphyton from Selected Sub-Samples
APPENDIX H PHOSPHORUS, NITROGEN AND CARBON CONTENT OF PERIPHYTON
FROM SELECTED SUB-SAMPLES
APPENDIX H . . . CONTINUED
APPENDIX H . . . CONTINUED
