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* Farm no longer active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

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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