1. Complexities of the Carters Lake TMDL Presented by: Jeremy Wyss, H.I.T. Tetra Tech Presented by: Jeremy Wyss, H.I.T. Tetra Tech 26th Annual Alabama Water Resources Conference September 6, 2012 26th Annual Alabama Water Resources Conference September 6, 2012

2. USACE Peak Power Pump Storage Operation ≈450 feet deep Tallest Earthen Dam East of Mississippi River ≈520 Square Miles Headwaters of Coosa River Carters Lake System

3. Year Coosawattee River at Georgia Highway 5 near Ellijay Mountaintown Creek at State Road 282 (US Hwy 76) near Ellijay Regulatory Limit (lb/year) 151,5008,000 200293,0362,734 2003106,62210,029 2004173,7487,006 2005248,49327,383 200685,3585,704 2007127,5772,714 2008127,5954,698 2009265,94819,658 TP – 8,000 pounds/year Mountaintown Creek at State Road 282 (US Hwy 76) near Ellijay TP – 151,500 pounds/year Coosawattee River at Georgia Highway 5 near Ellijay Watershed Standards

4. Chlorophyll a 5 µg/L (growing season average) Mid Lake - Upstream from Woodring Branch Chlorophyll a 10 µg/L (growing season average) Upper Lake - Coosawattee River Embayment Mouth pH 6.0 – 9.5 TN 4.0 mg/L in photic zone TP 172,500 lbs or 0.46 lb/acft DO 5.0 mg/L (daily average) not less than 4 mg/L pH 6.0 – 9.5 TN 4.0 mg/L in photic zone TP 172,500 lbs or 0.46 lb/acft DO 5.0 mg/L (daily average) not less than 4 mg/L Whole Lake (Elevation 1072) Lake Standards

5. Carters Modeling Models Outputs Water Surface Elevation Temperature and Dissolved Oxygen profiles Lake Concentrations (Chl-a, TN, NH3, NOx, OrgN, TP, PO4, OrgP, BOD5, DO, Temp) Subwatershed Flows Subwatershed Concentrations (Chl-a, TN, NH3, NOx, OrgN, TP, PO4, OrgP, BOD5, DO, Temp, TSS) EFDC Flows Temperatures Concentrations Carters Watershed Carters Lake LSPC Re-Reg Lake Re-Reg Watershed EFDC

6. Watershed Hydrology Calibration

7. Watershed Water Quality Calibration

8. Lake Hydrodynamics Calibration

9. Lake Water Quality Calibration

10. Model Scenarios Baseline  Model Calibration Full Permit  Point Sources and Water withdrawals at full permit No Point Sources  Point Sources and Water withdrawals removed All Forest (natural)  All land use area converted to Forest Future Land use  Land use processed with GLUT 2040 Reductions  Land use and point source % reductions Baseline  Model Calibration Full Permit  Point Sources and Water withdrawals at full permit No Point Sources  Point Sources and Water withdrawals removed All Forest (natural)  All land use area converted to Forest Future Land use  Land use processed with GLUT 2040 Reductions  Land use and point source % reductions

11. TMDL Status  Modeling and scenario runs are completed (GAEPD reviewing)  GAEPD/EPA looking into standard modifications Mountaintown Creek Total Phosphorus Lake Total Nitrogen Chlorophyll a  GAEPD looking into standard establishment Talking Rock Creek Reregulation Reservoir  Georgia Department of Natural Resources Board this fall  Modeling and scenario runs are completed (GAEPD reviewing)  GAEPD/EPA looking into standard modifications Mountaintown Creek Total Phosphorus Lake Total Nitrogen Chlorophyll a  GAEPD looking into standard establishment Talking Rock Creek Reregulation Reservoir  Georgia Department of Natural Resources Board this fall

12. Next Steps  Get TMDL approved  Incorporate modeling results into Georgia State Water Plan  Link Carters modeling to the GSWP Coosa River Basin model Investigate impacts on Coosa and Lake Weiss TMDL’s  Get TMDL approved  Incorporate modeling results into Georgia State Water Plan  Link Carters modeling to the GSWP Coosa River Basin model Investigate impacts on Coosa and Lake Weiss TMDL’s

13. Comments/Questions? Complexities of the Carters Lake TMDL Acknowledgements Dr. Elizabeth Booth, GAEPD Acknowledgements Dr. Elizabeth Booth, GAEPD