Total Maximum Daily Load Development for Unnamed Tributary to Pitts Creek. Public Meeting March 26, Why Are We Here

Transcription

1 Total Maximum Daily Load Development for Unnamed Tributary to Pitts Creek Public Meeting March, Why Are We Here. Learn about water quality of the stream. Discuss the Total Maximum Daily Load (TMDL) development. Gather comments and encourage public participation

2 The TMDL Process DEQ routinely monitors the quality of waters across the state and publishes a list of impaired waters every years Virginia is required by law to establish a TMDL for each pollutant causing an impairment A TMDL is the amount of a particular pollutant that a stream can receive and still meet Water Quality Standards Water Quality Standards Designated Uses Water Quality Criteria Recreation Aquatic life Fishing Shellfishing Drinking water Wildlife Dissolved Oxygen (DO) TMDL for the Unnamed Tributary to Pitts Creek Pitts Creek Maryland Unnamed Tributary to Pitts Creek Chesapeake Bay Virginia Eastern Shore Virginia Station 7-XAE. Designated Use: Aquatic Life Aquatic Life Intended to protect the propagation and growth of a balanced, indigenous population of aquatic life, including game fish, which might reasonably be expected to inhabit them.

3 Assess DO Attainment of Aquatic A Life Use Water Type Class III Nontidal Criteria Minimum: mg/l; Daily Average: 5 mg/l Listing Year 99 DO Observations in Unnamed Tributary to Pitts Creek DO(mg/L) 5 mg/l mg/l Sep-9 Sep-99 Sep- Sep- Sep- Sep- Sep- Sep-5 Sep- Sep-7 Unnamed Tributary to Pitts Creek Maryland Unnamed Tributary to Pitts Creek Virginia Station 7-XAE.

4 Land Use Distribution Crops 7.% Pasture/Hay.9% Urban.7% Commercial.% Transitional.% Water.% Wetland.7% Forest 7.% Data Analysis BOD mg/l Chla ug/l Oct -9 Oct -9 Oct-9 Oct-95 Oct -9 Oct -97 Oct-9 Oct-99 Oct - Nov- Jan- Mar- May- Jul- Sep- Nov- Jan- Mar- May-..5 Total NO-N mg/l.. Total Phosphate-P mg/l Oct-9 Oct -9 Oct -9 Oct -9 Oct- Oct- Oct - Oct - Oct-9 Oct -9 Oct -9 Oct -9 Oct- Oct- Oct - Oct -

5 Monthly DO distribution Dissolved Oxygen mg/l Month Causes of the Problem DO TN NH NO TP PO BOD 5 Chl ph (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (ug/l) Duration Count Mean Stand Deviation Background value for assessing. <. <. < natural condition EPA recommend nutrient values.7. Water Quality Assessment Guidance Manual, VA DEQ,, 5

6 Causes of the Problem Low flow High temperature High carbon deposition Low surface exchanges Caused by both natural condition and human impact TMDL Development Source analysis Use linked watershed and in-stream modeling approach Simulate daily nutrients and carbon loadings from watershed Discharge loads to in-stream model Use in-stream water quality model to simulate DO dynamics Calibrate water quality model Compute allowable loads and determine load reduction

7 Sources Agricultural Human Pets Livestock Wildlife Approach Source Analysis GIS land use data (land use, population, pets, septic system) Wildlife survey data (animal density, animal habitat) Shoreline survey data Sources N-fertilizer applied to the cropland is 5 lb/acre/year Lawn fertilizer loading is lbs/acre/year Nutrient contribution from atmospheric deposition TN =. lb/acre/year TP =.7 lb/acre/year 7

8 Source Analysis Results Sub-watershed 5 7 Human Dog Cattle Swine 7 7 Livestock Horse Sheep Chicken*,,7 5,,7 9,,,77, Duck Geese Wildlife Deer Raccoon 57 7 * The current data is not available. The number does not include new chicken farms be added in the watershed in recent years. Modeling Approach Conduct source analysis Analysis nutrients and carbon inputs from different sources Use LSPC to simulate watershed processes Use a spatially varying water quality model (EFDC) to simulate in-stream DO processes Tide Temperature Salinity Solar radiation Model Linking Structure Watershed model Hydrodynamic Model Organic matter Flow Nutrient and carbon loads Water column WQ model Sediment process model Algae Nitrogen Phosphorus Carbon DO Sediment fluxes (nutrients and SOD)

9 Model Results... Standard Observation. 7.. Observation DO (mg/l)... TKN (mg/l) //999 5/5/ 9/7/ /9/ // //999 5/5/ 9/7/ /9/ //.. Observation.. Observation NO (mg/l).... TP(mg/L) //999 5/5/ 9/7/ /9/ //. //999 5/5/ 9/7/ /9/ // TMDL Endpoint The Creek is influenced by both natural condition and human impact Use in-stream nutrient criteria to set the target of nutrient reduction Endpoint Virginia Screening level: TN=. mg/l and TP =. mg/l EPA recommended level: TN=.7 mg/l and TP =. mg/l 9

10 Allowable Load Calculation Conduct -year simulation Reduce load until in-stream averaged nutrient concentrations (TN and TP) meet the criteria (endpoint) Establish TMDL and load reduction Model Scenario Runs Existing 5% reduction 7% reduction Criteria (mg/l) Name Con. Load Con. Load Con. Load VA EPA mg/l (lb/day) mg/l (lb/day mg/l (lb/day) Screening TN TP TMDL Nutrient TMDL (lb per day) Based on EPA Recommend Criteria Nutrient TN TP TMDL 5.5. = = = LA.9.5 WLA N/A N/A FA N/A N/A MOS.. TMDL = Total Maximum Daily Load LA = Load Allocation (Nonpoint Source) WLA = Waste Load Allocation (Point Source) FA = Future Allocation MOS = Margin of Safety (5%)

11 DO Distribution After Load Reduction DO (mg/l) 5% reduction of TN, TP, and OC. Observationa. Standard //999 5/5/ 9/7/ /9/ // DO (mg/l) Standard 7% Reduction of TN,TP, and OC Observationa //999 5/5/ 9/7/ /9/ // Questions?