1. High Rock Lake TMDL Development
Michelle Woolfolk, NC DWQ
May 24, Stakeholder Meeting

2. Topics to cover Regulatory basis Process for strategy development
Timeline
Monitoring and modeling
Questions and discussion

3. Acronyms, acronyms Environmental Management Commission (EMC)
North Carolina List of Impaired Waters (303(d) List)
National Pollutant Discharge Elimination System (NPDES)
Division of Environmental Management (DEM)
Total nitrogen (TN)
Total phosphorus (TP)
Total Maximum Daily Load (TMDL)
US Environmental Protection Agency (EPA)
US Geological Survey (USGS)
Alcoa Power (APGI)

4. Regulatory basis
High Rock Lake appears on the 2004 North Carolina 303(d) list
acres impaired due to chlorophyll a
11,305 acres impaired due to turbidity
Clean Water Act requires TMDLs for waters impaired by a pollutant

5. 40CFR130.7(c)
States (and EPA) shall establish TMDLs for the water quality limited segments (identified in the 303(d) list)
TMDLs shall be established at levels necessary to attain and maintain the applicable narrative and numerical water quality standards, with seasonal variations and a margin of safety …
Determinations of TMDLs shall take into account critical conditions for stream flow, loading, and water quality parameters

6. 40CFR103.7(c) cont.
All TMDLs for water quality limited segments (303(d) list) will be submitted to EPA for review and approval.

7. What does TMDL stand for?
Total Maximum Daily Load
TMDLs are written plans for attaining and maintaining water quality standards, in all seasons, for a specific waterbody and pollutant.

8. Elements of a TMDL 1. Problem identification 2. Target analysis
3. Source assessment
4. Linkage of source and target
5. Determine maximum allowable load
6. Allocation of load/wasteload
7. Public participation

9. Federal regulatory authority
EPA Region IV oversight
Modeling
Target setting
Allocations (Reasonable assurance)
NPDES permitting
Compliance schedules
Approval/Disapproval of final TMDL

10. Strategy development process
Step 1
Build the tools (models)
Systematic planning
Monitoring
Modeling
Step 2
Develop the strategy
Target setting
Allocations
Point and nonpoint strategies
Environmental Management Commission

11. Systematic planning Based on EPA guidance for environmental projects
Development of a monitoring and modeling study plan
Outlines project responsibility
Describes project goals
Describes modeling approaches
Outlines monitoring plan
Step 1. Build the tools

12. Describe the impairment
What is the water quality standard?
Addressing duration and frequency
At what location was the reason for listing determined?
DWQ ambient monitoring location(s)
Coalition/Basin Association monitoring
Step 1. Build the tools

13. Supporting Information
Data availability
Ambient monitoring (DWQ or coalition)
NPDES instream monitoring
USGS flow stations
Special studies (DWQ, discharger, coalition, USGS, university, other?)
Rarely have all of the data listed above.
Step 1. Build the tools

14. Monitoring
Monitoring plan and data needs in monitoring and modeling study document
Monitoring plan for scoping study available on internet as stand-alone memorandum.
Step 1. Build the tools

15. Modeling: Linking causes and sources
Model selection
Data availability
Watershed and reservoir characteristics
EPA guidance (e.g., Nutrient TMDL Protocol)
Experience (personally and as a unit)
Schedule
Model calibration
Critical conditions
Step 1. Build the tools

16. OK, now we have a calibrated nutrient response model, what next?
Figure out how to use it!!!!

17. Addressing the standard
What are the critical conditions? How are they determined?
Frequency of violations, magnitude of violations
Temporal averaging
Spatial averaging
Step 2. Develop strategy

18. Target setting Assimilative capacity determination
Reduction needed? (TMDL needed) Loading cap? Remaining capacity?
How much can I pour without going over?
Step 2. Develop strategy

19. Target setting, cont. Water quality standards
Chlorophyll a
Turbidity
Dissolved oxygen pH
Control of TN and/or TP may be needed
Step 2. Develop strategy

20. Allocations
Typically allocated the allowable load between point sources (wasteload) and nonpoint sources (load)
Who gets the biggest piece of the pie?
Equity versus efficiency
Step 2. Develop strategy

21. How are targets achieved?
Point source allocations
Each discharger assigned a mass loading allocation
Provisions for another compliance group
May require rulemaking
Nonpoint source management
May include buffers, stormwater controls on existing and/or new development, agriculture
Step 2. Develop strategy

22. State regulatory authority
The NC Environmental Management Commission
NPDES permitting
Nonpoint source management
Rulemaking
Step 2. Develop strategy

23. Strawman schedule

24. Questions? Michelle Woolfolk or George Hunt
NCDWQ – Modeling & TMDL Unit
1617 Mail Service Center
Raleigh, NC
(919) ext. 505