2 – TMDL Development Essentials

1. 2 – TMDL Development Essentials Virginia Tech Biological Systems Engineering Department 2013

2. Overview/Objectives • Watershed Management – Understand watershed management concept with focus on adaptive management • TMDL Development Process - Identify the steps taken during development of a TMDL • TMDL Project Participants– Identify the groups and individuals involved in developing a TMDL

3. What is a Watershed? • The land area that drains to a common waterway, such as a stream, lake, estuary, wetland, or ultimately the ocean.

4. What is Watershed Management? • Watershed management recognizes that the water quality of our streams, lakes, and estuaries results from … • Human activities • Watershed characteristics in upstream areas • The goal of watershed management is … • An environmentally and economically healthy watershed • One that benefits all stakeholders (water quality and living resources) • Each watershed management plan includes • Unique goals • Site-specific management strategies to achieve those goals

5. Effective Watershed Planning is … • Iterative and adaptive • Holistic • Geographically defined • Integrated with other planning efforts • A collaborative and participatory process

6. Three Tiers of TMDL Program • TMDL Study • Development of an Implementation Plan • Implementation of Pollutant Control Measures

7. What is a TMDL? • A Total Maximum Daily Load (TMDL) quantifies the amount of a particular pollutant a waterbody can receive and still meet water quality standards (pollutant budget). TMDL = WLA + LA + MOS Where: WLA = waste load allocation (point sources) LA = load allocation (nonpoint sources) MOS = Margin of safety

8. 8 Existing Condition TMDL Scenario Conceptual TMDL Concentration Water Quality Standard Concentration, C (mg/L) Time

9. TMDL Target Margin of Safety Concentration or Load Time Margin of Safety • MOS can be explicit or implicit

10. TMDL Development Process • Identify the extent/degree of the impairment • Pollutant identification, endpoint definition/comparison • Characterize watershed and pollutant sources • Determine existing and potential future pollutant loads (model inputs) • Watershed characterization (model inputs) • Link pollutant sources to waterbody water quality • Pollutant fate and transport modeling • Existing and future conditions • Use model to quantify the TMDL • Define the pollutant load reductions required to achieve applicable water quality criteria

11. 1. Identify Extent of Impairment Assessment Period Water Quality Criterion

12. Identify Extent of Impairment

13. 2. Characterize Watershed and Pollutant Sources • Gather and analyze existing data • Identify data gaps and, if possible, collect additional data • Identify and characterize pollutant sources • Assess unique features • Assess existing management measures • Tour the watershed

14. GIS Analysis

15. Pollutant Source Types • Nonpoint Sources (NPS) • Driven by rainfall-runoff • Agriculture, construction, forest harvesting, urban runoff • Direct input to water bodies • Independent of rainfall • Household sewage • Aquaculture and mariculture • Direct deposit • Point Sources (PS) • Independent of rainfall • Industrial and municipal sources

16. Wildlife Livestock Crops Forest Pasture Residential Stream Humans and Pets Sources and Distribution of Bacteria

17. Pollutant Source Load Inventory • Different source categories (e.g. by land use) • Loading mechanism • To the land surface (e.g. fertilizer) • Direct to stream • Point sources (e.g. industry) • Direct diffuse sources (e.g. household sewage) • Load estimates • Distributed spatially (e.g. by sub-watershed) • Distributed temporally (e.g. monthly)

18. 3. Link Pollutant Sources to Water Quality • Watershed model • Watershed characterization • Source characterization • Climate variability • Fate and transport • Allocation analysis Models are used to predict how watersheds respond, and to evaluate pollutant reduction options = X Land use and Management Stream Network Source: EPA 841-B-05-005

19. Load at the Watershed Outlet Load Delivered to Edge-of-Stream The Role of Models in TMDLs Fate, Transformation, and Delivery Load Applied to the Land Direct Inputs

20. TMDL Modeling • Computer-based water quality simulation models used extensively to develop TMDLs • Many models have the capability to simulate watershed-scale processes over range of flow conditions and can evaluate effectiveness of proposed control measures (best management practices, BMPs) • Preferred models used in Virginia • HSPF – Hydrological Simulation Program-FORTRAN • GWLF – Generalized Watershed Loading Function

21. 4. Use Model to Determine TMDL = X Land use and Management Stream Network Source: EPA 841-B-05-005 Identify reductions needed to meet water quality standards Alternative combinations of reductions from different sources Starting Load – Reductions = Allocated Load

22. TMDL Pollutant Budget Guidelines TMDL meets water quality standards Includes point and nonpoint sources Considers background contributions Considers critical conditions Considers seasonal variations Considers future growth Includes a margin of safety Includes public participation

23. Successful TMDL Allocation

24. Calculate Load Allocations by Source Example for bacteria

25. TMDL Report • Basis for the impairment • Watershed characterization • Model development • TMDL quantification • TMDL allocations • Next steps toward implementation • Reasonable assurance • Public participation

26. The TMDL Project Participants • TMDL Project Manager • Regional Biologist/Monitoring Staff • Permitting Staff • Contractor • Watershed Liaison • Technical Advisory Committee (TAC) • Stakeholders

27. TMDL Project Manager • Facilitates overall project progress • Coordinates DEQ data delivery to contractors (AWQM, DMR, SIR, VPDES, WWTP, fish advisories, consent decrees, etc.) • Manages schedule for interim product delivery • Evaluates and provides feedback on products http://media1.break.com/breakstudios/2013/7/18/The-Most-Interesting-Man-in-the-World-LARGE.jpg El Jefe “The Boss”

28. Regional Biologist/Monitoring Staff • Provides all monitoring data to TMDL Project Manager for delivery to Contractors • Provides a detailed basis for impairment • Responds to questions regarding impairment • Assists with interpretation of benthic metrics in light of local stream conditions

29. Permitting Staff • Reviews permit-related data and provides feedback to TMDL Project Manager for delivery to Contractors as needed • Provide interpretation/ clarification of permit as needed • Provides input on development of existing WLAs and WLAFG as needed

30. Contractor • Provides data analysis • Recommends TMDL endpoint and modeling approach as needed • Performs TMDL modeling • Creates alternative TMDL allocation scenarios • Writes the TMDL study report = X Land use and Management Stream Network Source: EPA 841-B-05-005

31. Watershed Liaison • Coordinates watershed visits • Identifies local issues • Arranges introductions to knowledgeable and vocal stakeholders • Helps arrange local public hearings

32. Technical Advisory Committee • Provides local insight on watershed issues, characteristics, etc. • Evaluates and provides feedback on interim data and results presented at TAC meetings • Evaluates and provides feedback on allocation scenarios

33. Stakeholders • Provide additional data (e.g. land use, future conditions, historical loads, local ag. practices) • Actively engage additional stakeholders – peer to peer outreach • Identify technical/data resources

34. Questions / Comments