Post on 02-Jan-2016
Chowan River TMDL Development
Tidewater Area
08/26/04
TMDL Development
Historical data analysis Source assessment
Bacterial source tracking Modeling Allocation
Fecal Coliform ImpairmentsImpaired Stream Segments in the Back Bay and North Landing River watersheds
Water Quality Data AnalysisLocation of VADEQ water quality monitoring stations in the Back Bay and North Landing River watersheds
Water Quality Data Analysis
Fecal Coliform Concentrations
Impairment Station Id Sampled Dates Count Minimum Maximum Mean Median % Violations
1000 % Violations
400
Milldam Creek 5BMLD001.92 9/95-3/04 83 49 8,000 406 100 11 17 Nawney Creek 5BNWN000.00 6/93-3/04 100 25 4,700 589 200 17 34 Nawney Creek 5BNWN001.84 6/93-3/04 100 25 2,900 528 210 18 38
West Neck Creek 5BWNC006.64 6/72-5/79 70 19 8,000 953 105 21 27 West Neck Creek 5BWNC010.02 9/95-3/04 86 22 2,000 715 350 31 49
Water Quality Data Analysis
E. coli concentrations for period July 2002 through March 2004
Impairment Station Id Count Minimum Maximum Mean Median
% Violations 235
Milldam Creek 5BMLD001.92 10 10 620 184 75 30 Nawney Creek 5BNWN000.00 10 10 750 159 60 20 Nawney Creek 5BNWN001.84 9 10 420 139 90 22 West Neck Creek 5BWNC010.02 11 10 800 264 200 45
Water Quality Data Analysis Statistical Analysis of Water Quality Measurements
versus Precipitation to determine the relationship between rainfall and water quality
Summary of the Mood Median Test on mean monthly precipitation at station 444101 (p=0.013).
Month Mean (in)
Minimum (in)
Maximum (in)
Median Groups
January 3.93 0.54 8.06 A B February 3.15 0.54 5.63 A B March 4.36 1.34 8.27 A B April 3.40 0.64 7.64 A B May 3.95 1.02 7.93 B June 3.15 0.35 5.78 A B July 4.48 0.04 8.17 B August 4.35 0.44 12.49 A B September 4.77 0.58 16.85 A B October 3.52 0.00 9.53 A November 3.29 0.42 7.00 A B December 3.22 0.56 7.03 A B
Source Assessment
Identification of Sources DEQ/DCR/Locality records Ag Census Habitat Analysis Stakeholders, local knowledge BST
Source Characterization Fecal production / densities / distribution
Delivery Mechanisms Direct Land-applied Exported Out of Watershed
Temporal Variation
Permitted Discharges
Facility Permit No. Type Fecal Control
MS4 VAR040043 Storm water No
Barry D Knight Hog Farm* VPG150001 CAFO No
* Farm no longer active
Two permitted dischargers – one in West Neck, one in Nawney Creek.
Only one is currently active.
Human (2004)
ImpairmentPopulatio
n
Housing Units (HU)
HU with Sewer
HU with Septic
HU with Other
Milldam Creek 151 57 1 51 5Nawney Creek 703 264 0 260 4West Neck Creek 45,465 15,189 13,597 1,572 20
Human
Sanitary sewer Overflows - reported to DEQ Exfiltration – rate from literature
Failing septic systems Rate based on age of house
Straight pipes U.S. Census and VDH consultation
Reported Sewer Overflows
Frequent overflows in West Neck Creek Drainage.
55 events reported between July 1999 and May 2004.
Uncertainty as to whether all overflows are reported/observed.
Mean overflow volume of 109 gallons.
Pets (2004)
Impairment Dogs CatsMilldam Creek 30 34Nawney Creek 141 158West Neck Creek 8,111 9,083
Estimated Livestock - 1997
Impairment Beef Dairy Horse Sheep Poultry Swine
Nawney Creek 8 1 267 20 0 5187*
West Neck Creek 11 0 425 32 0 8280*
Milldam Creek 0 0 25 2 0 494*
Estimated Livestock - 2002
Impairment Beef Dairy Horse Sheep Poultry Swine
Nawney Creek 8 1 267 20 0 3705*
West Neck Creek 11 0 425 32 0 377*
Milldam Creek 0 0 25 2 0 23*
Livestock
Average percentage of collected livestock waste applied throughout year
Month Applied % of Total Land use Dairy Beef Swine Poultry January 1.50 8.33 0.00 N/A Cropland February 1.75 8.33 0.00 N/A Cropland March 17.00 8.34 20.00 N/A Cropland April 17.00 8.34 20.00 N/A Cropland May 17.00 8.33 20.00 N/A Cropland June 1.75 8.33 0.00 N/A Pasture July 1.75 8.33 0.00 N/A Pasture August 1.75 8.33 0.00 N/A Pasture September 5.00 8.34 0.00 N/A Cropland October 17.00 8.34 20.00 N/A Cropland November 17.00 8.33 20.00 N/A Cropland December 1.50 8.33 0.00 N/A Cropland
Wildlife Population
Impairment Deer Goose Duck Muskrat Raccoon Beaver Seagull
Milldam Creek 23 8 21 5124 1304 42 TBD
Nawney Creek 49 17 44 2557 332 34 TBD
West Neck Creek194 66 175 13327 167 118 TBD
Wildlife
Animal Type Portion of Day in Stream Access Areas
Direct Deposition
Time of Day Loads Produced
(%) (%) (hr) Deer 5 1 6PM – 6AM Raccoon 5 5 6PM – 6AM Muskrat 90 5 6AM – 6PM Beaver 100 100 6AM – 6PM Turkey 5 1 6AM – 6PM Goose 50 5 6AM – 6PM Duck 75 5 6AM – 6PM Seagull 50 5 6AM – 6PM
Source AssessmentAnimal Waste Load
(lb/an-day) Fecal Coliform Density
(cfu/lb) # Dairy Cow Equivalents
Dairy 120.4 1.23E+08 1 Beef 46.4 4.58E+07 7
Horse 51.0 4.26E+07 7 Swine 11.3 1.81E+08 7 Sheep 2.4 1.95E+07 316 Goat 5.7 6.80E+06 382
Broiler 0.2 2.66E+08 328 Layer 0.3 2.66E+08 214
Human 0.9 2.91E+08 58 Dog 1.0 2.18E+08 69 Cat 0.0 4.08E+03 84,765,882
Raccoon 1.0 9.53E+08 16 Muskrat 0.2 8.62E+08 78 Beaver 0.4 4.54E+05 74,001 Deer 1.7 1.72E+08 50
Goose 0.5 1.13E+08 263 Mallard 0.3 1.59E+06 28,191 Seagull 0.002 1.68E+11 40
Bacterial Source Tracking
Location of BST stations in the Back Bay and North Landing River watersheds
Modeling
Hydrologic model Runoff model HSPF
Water Quality model Tidal/Estuary model CE-QUAL-W2
Model Calibration and Validation Based on data availability, period of
interest
Modeling
$
Modeling
$
Modeling
VADEQ Station 5BWNC010.02 and USGS Station #02043200
1
10
100
1,000
10,000
100,000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fec
al C
olif
orm
(cf
u/1
00m
l)
Listing Standard New Instantaneous Standard Observed FC
High Flow Moist Conditions Mid-Range Flow Dry Conditions Low Flow
Modeling
VADEQ Station 5BMLD001.92 and USGS Station #02043200
1
10
100
1,000
10,000
100,000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fec
al C
olif
orm
(cf
u/1
00m
l)
Listing Standard New Instantaneous Standard Observed FC
High Flow Moist Conditions Mid-Range Flow Dry Conditions Low Flow
Modeling
1
10
100
1,000
10,000
100,000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fec
al C
olif
orm
(cf
u/1
00m
l)
Listing Standard New Instantaneous Standard Observed FC
High Flow Moist Conditions Mid-Range Flow Dry Conditions Low Flow
VADEQ Station 5BNWN001.84 and USGS Station #02043200
Modeling
1
10
100
1,000
10,000
100,000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fec
al C
olif
orm
(cf
u/1
00m
l)
Listing Standard New Instantaneous Standard Observed FC
High Flow Moist Conditions Mid-Range Flow Dry Conditions Low Flow
VADEQ Station 5BNWN000.00 and USGS Station #02043200
Hydrologic CalibrationSample
$
0
2,000
4,000
6,000
8,000
10,000
12,000
Oct
-88
Dec
-88
Mar
-89
Jun-
89
Sep
-89
Dec
-89
Mar
-90
Jun-
90
Sep
-90
Dec
-90
Mar
-91
Jun-
91
Sep
-91
Dec
-91
Mar
-92
Jun-
92
Sep
-92
Dec
-92
Mar
-93
Jun-
93
Sep
-93
Flo
w (
cfs)
Observed Modeled
Hydrologic CalibrationSample
$
Observed Modeled Error Target
(in) (in) (%) (%)
68.84 66.87 -2.9 1028.98 26.98 -6.9 1512.25 11.93 -2.6 1028.05 24.73 -11.8 3019.94 23.18 16.3 308.66 8.16 -5.9 3012.20 10.80 -11.4 3055.14 59.57 8.0 2024.66 22.92 -7.0 3016.52 21.36 29.3 305.21 6.34 21.6 308.76 8.96 2.3 30
Total In-stream FlowUpper 10% Flow Values
Total Storm Volume (in)Winter Storm Volume (in)Spring Storm Volume (in)
Lower 50% Flow ValuesWinter Flow Volume (cfs)Spring Flow Volume (cfs)Summer Flow Volume (cfs)
Criterion
Summer Storm Volume (in)Fall Storm Volume (in)
Fall Flow Volume (cfs)
Allocation
Develop reduction scenarios that will meet water quality standards 100% reduction in straight pipes, 25%
reduction in failed septic systems 100% reduction in straight pipes, 50%
reduction in livestock direct deposition Allocate loads to each source
Allocation
Time, (days)
FC
Con
c., (
cfu/
100m
l)
Historical Data
TMDL