High Rock Lake TMDL Development Michelle Woolfolk, NC DWQ May 24, 2005 Stakeholder Meeting

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

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)

Regulatory basis High Rock Lake appears on the 2004 North Carolina 303(d) list 5568.8 acres impaired due to chlorophyll a 11,305 acres impaired due to turbidity Clean Water Act requires TMDLs for waters impaired by a pollutant

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

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

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Strawman schedule

Questions? Michelle Woolfolk or George Hunt NCDWQ – Modeling & TMDL Unit 1617 Mail Service Center Raleigh, NC 27699-1617 (919) 733-5083 ext. 505 Michelle.Woolfolk@ncmail.net George.Hunt@ncmail.net