Resizing a river Resizing a river : using experimental management : using experimental management to develop a downscaled environmental flow to develop a downscaled environmental flow

regime for the Lower Bridge Riverregime for the Lower Bridge Riverregime for the Lower Bridge Riverregime for the Lower Bridge Riveroror

DoesDoes more water mean more fish?more water mean more fish?Does Does more water mean more fish?more water mean more fish?

Mike BradfordMike Bradford

Paul Higgins

Josh Korman

Alternative Perspectives on Alternative Perspectives on Flow Flow M tM tManagement: Management:

Natural Flow ParadigmNatural Flow Paradigm “Nature knows best”“Nature knows best”

Designer FlowsDesigner Flows Flows for target species Flows for target species

Flows for ecosystem Flows for ecosystem healthhealth

or management goalsor management goals River resizingRiver resizing

The magnitude of the The magnitude of the impact is related to the impact is related to the “degree of hydrologic“degree of hydrologic

More water ≠ more fish More water ≠ more fish degree of hydrologic degree of hydrologic

alteration”alteration” More water = more fishMore water = more fish

Experimental Management as a Experimental Management as a p gp gmanagement paradigmmanagement paradigm

Substantial uncertainty in instream flow Substantial uncertainty in instream flow methodologies, most are not testedmethodologies, most are not tested

Variable and unpredictable responses of the Variable and unpredictable responses of the ecosystem to flow changesecosystem to flow changes

Instead of flow modelling, empirically determine Instead of flow modelling, empirically determine response of the river to flow by testing a range of response of the river to flow by testing a range of flow regimes flow regimes

Bridge River, southwestern BC

Present location of Terzaghi Dam

MAD ~100 m3s

Fish production in tributaries

Terzaghi Dam, ca 1958g ,

Antoine Creek

30.4 km

26.4 km

23.6 km

20 km

Reach 2Reach 3

Michelmoon Creek

36.5 km

33.3 km

Reach 1Yankee Creek 

Hell Creek

Camoo CreekTerzaghi 

D

R4 MAD = 0cms

R3 MAD ~ 0.6 cms36.5 km

39.5 km

Reach 4 

Mission CreekDam

CarpenterReservoir 

R2 MAD ~ 5.6 cms

100% diversion for power

Terzaghi DamReach 4

Reach 2Reach 3

Mid 1990s: the reintroduction of flow Mid 1990s: the reintroduction of flow d 990 odu o o od 990 odu o o ofrom from TerzaghiTerzaghi DamDam

Modification of the damModification of the dam How much water to How much water to

release?release? Water is worth 2Water is worth 2--3 M$ per 3 M$ per

annualized mannualized m33/s for power /s for power generationgeneration

At the time, juvenile salmon At the time, juvenile salmon were the primary were the primary environmental performanceenvironmental performanceenvironmental performance environmental performance measuremeasure

Standard physical Standard physical habitat simulation in habitat simulation in Reach 3 predicted Reach 3 predicted that a large flow that a large flow release would reducerelease would reduce 0 4

0.5

release would reduce release would reduce juvenile fish habitatjuvenile fish habitat

0.3

0.4ParrParr

FFUW

)This is counter to

S lh d

0.1

0.2 FryFry

P(W

Ustandard setting approaches used by agencies

Steelhead0.00 4 8 12 16 20

River discharge (cms)

More water ≠ more fish! Prediction: Optimal flows at Prediction: Optimal flows at 11 33 cmscms (1(1 3%3% MAD)MAD)11--3 3 cmscms (1(1--3% 3% MAD)MAD)

A flow experiment was recommended to A flow experiment was recommended to arbitrate between competing hypothesesarbitrate between competing hypothesesarbitrate between competing hypothesesarbitrate between competing hypotheses

HH11: : “More flow “More flow produces more fish”produces more fish” 75produces more fishproduces more fish

Fish production Fish production is direct is direct function of the relationship function of the relationship between wetted area and between wetted area and flfl

50('000

)

flowflow

25

Smol

ts

HH22: : “More flow will not “More flow will not produce more fish”produce more fish”

Habitat quality changes with Habitat quality changes with

00 1 2 3 4 5

Ri Di h ( )q y gq y gflow, and after some flow, and after some threshold point this causes threshold point this causes a net reduction in fish a net reduction in fish production production

River Discharge (cms)

pp

Recommended planned flow 12

14

16

s)

3 cms WUP6 cms WUP6 cms modified

planned flow treatments:

6

8

10

Rel

ease

(cm

Seasonal flow variation “semi- 2

4

6

Dam

natural flow”

4-year 7ud

get

0

Jan

Feb

Mar Apr

May Ju

nJu

l

Aug

Sep Oct

Nov

Dec

4-year treatment blocks 4

5

6

se W

ater

Bu

/y)

PlannedRealized

blocks

1

2

3

Dam

Rel

eas

(cm

s

0

1

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014A

nnua

l

Reintroduction of continuous flowscontinuous flows began August 1, 2000

Hall et al 2009

Before Afterch

4

Rea

ch

3R

each

Monitoring Design Monitoring Design

PrePre--release: 1996release: 1996--19991999 Release year: 2000Release year: 2000 Post release: 2001Post release: 2001--20082008 Post release: 2001Post release: 2001--20082008 Basic unitBasic unit-- 3 pass backpack E/f 3 pass backpack E/f 1212--18 sites in each of 3 reaches18 sites in each of 3 reaches Additional indicators:Additional indicators:

Fish conditionFish condition Lower Lower trophictrophic levelslevelspp Physical and chemical monitoringPhysical and chemical monitoring

Hierarchical model for analyzing electrofishing data

mr hrLoop over reaches (r)

wr r Nucr

l Nus Nss

Ntotr Ntot

lr Nusr Nssr

l ,r l ,r

ai i

lLoop over passes (j)

li ci,j

Ni,1 Ni,j Ni,j+1

Loop over sites (i)

300

All Reaches Reach 3 Age-0 rainbow

150

200

250

danc

e ('0

00s)

100

150

danc

e ('0

00s)

Median

trout

0

50

100Abu

nd

0

50Abu

nd

abundance and 95% credible

1996 2000 2004 2008

60

Reach 2

1996 2000 2004 2008

Reach 4

credible intervals of abundance by

d

40

50

60

e ('0

00s)

100

150

e ('0

00s)

year and reach.Dashed horizontal li h th

10

20

30

Abu

ndan

ce

50

100

Abu

ndan

ce lines show the average abundance pre- and post-flow release

1996 2000 2004 2008

0

1996 2000 2004 2008

0

120

All Reaches

80

Reach 3 Age-1 rainbow trout

60

80

100

danc

e ('0

00s)

40

60

danc

e ('0

00s) Median

abundance d 95%

0

20

40

Abu

nd

0

20Abu

nd and 95% credible intervals of

1996 2000 2004 2008

Reach 2

1996 2000 2004 2008

Reach 4

abundance by year and reach

10

15

e ('0

00s)

30

40

50

e ('0

00s)

reach.

Dashed horizontal lines show the

5Abu

ndan

ce

10

20

Abu

ndan

ce average abundance pre- and post-flow release

1996 2000 2004 2008

0

1996 2000 2004 2008

0

120

All Reaches

100

Reach 3 Age-0 Coho salmon

60

80

100

danc

e ('0

00s)

60

80

danc

e ('0

00s)

0

20

40

Abu

nd

0

20

40

Abu

nd

Posterior distributions of abundance of

1996 2000 2004 2008

35

Reach 2

1996 2000 2004 2008

70

Reach 4

abundance of pre- and post-flow release

20

25

30

35

e ('0

00s)

40

50

60

e ('0

00s)

5

10

15

Abu

ndan

ce

10

20

30

Abu

ndan

ce

1996 2000 2004 2008

0

1996 2000 2004 2008

0

140

All Reaches

120

Reach 3 Age-0 chinook

60

80

100

120

ance

('00

0s)

60

80

100

ance

('00

0s)

Median

salmon

0

20

40

60

Abu

nd

0

20

40Abu

nd

Median abundance and 95% credible

1996 2000 2004 2008

0

Reach 2

1996 2000 2004 2008

0

Reach 4

credible intervals of abundance by

30

40

50

e ('0

00s)

4

6

e ('0

00s)

year and reach.

10

20

30

Abu

ndan

ce

2

4

Abu

ndan

ce

1996 2000 2004 2008

0

1996 2000 2004 2008

0

Is the Is the chinookchinook salmon decline caused by the impact salmon decline caused by the impact of of the altered thermal the altered thermal regime on regime on abundance?abundance?gg

0+ Chinook0+ Chinook

Site 30.4 Mean Temperature

14

0+ Chinook abundance: decline due to change in life

0+ Chinook abundance: decline due to change in life6

8

10

12

ter T

emp

(C)

0 cms3 cms6 cms change in life

history caused by increased larval development

change in life history caused by increased larval development

0

2

4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Wat

prates

prates

Site 30.4 Estimated Chinook Emergence Dates

0 cms3 cms

Wat

er B

udge

t 3 cmsOption 1Option 2Option 3Option 4O ti 5

3-N

ov10

-Nov

17-N

ov24

-Nov

1-D

ec8-

Dec

15-D

ec22

-Dec

29-D

ec5-

Jan

12-J

an19

-Jan

26-J

an2-

Feb

9-Fe

b16

-Feb

23-F

eb2-

Mar

9-M

ar16

-Mar

23-M

ar30

-Mar

6-A

pr13

-Apr

Est. Earliest Emergence Date

Option 5aOption 5b

Summary of change over all 4 fish taxaSummary of change over all 4 fish taxa

R tt dLittle change 3x increase Rewetted

Is habitat in the Bridge River too complex to model or predict?

What have we learned?

1. Biology

P i t th fl l th B id Ri• Prior to the flow release the Bridge River was a productive salmon river

• Increasing the flow to the wetted reach had no effect on salmon abundance- this was contrary to

di ti b d h bit t d h d lipredictions based on habitat and hydraulic modelling

•Each fish taxa responded differently

• Possible to “resize the river”- a smaller flow release would likely provide similar benefits

What have we learned, con’t2. Resource management

• The river is not a “scientist’s sandbox”s o a s s s sa dbo

• We did not capture the important values to stakeholdersstakeholders

• Esthetic and cultural values strongly support higher flowshigher flows

5

6

7

Wat

er B

udge

t

PlannedRealized

1

2

3

4

Dam

Rel

ease

W(c

ms/

y)

0

1

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014An

nual

D

Is monitoring and adaptive management an Is monitoring and adaptive management an ffi i t th d f tffi i t th d f tefficient method of resource management efficient method of resource management

decision making?decision making?

Long trials are difficult to sustain in today’s world ($$, time, shifting social environment)

Key questions may be less relevant by the end Lower requirement for accurate biological

information in complex decision environments where many factors are in play.

Value of information analysis at local and regional scales

See you in 2016 for the final See you in 2016 for the final yychapter!chapter!