Pre-RES TP Watershed Modeling/Review

1. Pre-RES TP Watershed Modeling/Review Kaufenberg, Wasley and Lindon

2. Outline • Background • Historic TP Limits • New River Eutrophication Criteria • New Process • WQ Analysis • Modeling • Watershed Assessment Status • Examples • Challenges

3. TP limits over the past 14 years

4. Watersheds of eutrophication impaired lakes

5. Process

6. Previous Analysis Memo

7. River eutrophication standards (RES)

8. RES • Region TPChl-a DO flux BOD5 • mg/L μg/L mg/L mg/L • North ≤0.050 ≤7 ≤3.0 ≤1.5 • Central ≤0.100 ≤18 ≤3.5 ≤2.0 • South ≤0.150 ≤35 ≤4.5 ≤3.0

9. RES: TP + response = impaired

10. Test run

11. New River Evaluation Decision Tree

12. New Pre-TMDL Analysis

14. Example Montevideo WWTP Chippewa Watershed

15. North Fork Crow Example

16. Sauk River Watershed Example • Sauk River Chain of Lakes TMDL • Recent point source reductions

17. TP Loading

18. Meeting Standards

19. WWTPs in the Rum Watershed

20. Rum River • Mixed landuse • Urban • Forest and wetlands • Agriculture • Outstanding resource value water • Excellent smallmouth bass fishery

21. Potential eutrophication status in Rum R. Proposed RES: TP: 0.100 mg/L, Chl-a: 18 µg/L Rum (2002-2011): TP: 0.116 mg/L, Chl-a: 21 µg/L

22. Concentration varies with flow

23. Little improvement in WWTP loads

24. WWTPs • 11% of annual TP load on average year (WWTPs = 11,402 kg/yr) • Cambridge is 9,062 kg/yr (79% of wastewater load) • Lake Pepin WQBEL for Cambridge 2,122 kg/yr • Compliance: no later than by May 31, 2015

25. Permitted vs actual loads • Permitted Lake Pepin loads: 9,866 kg/yr • Based on AWWDF or MDF and concentration multiplier • All facilities above Lake Pepin in entire basin are already only 60% of Lake Pepin allocations • Expected load from WWTPs in the Rum (3,500- 4,000 kg/yr) • This will reduce concentration during critical flows in the Rum River • Full discharge of Lake Pepin WQBELs??

26. Phosphorus Loading Assessment Status

27. Summary • Look at lakes, rivers and WWTPs in HUC 8 watershed • Use models if possible to look at all point and non-point sources at once similar to a TMDL or WRAP • This does not exist for all watersheds • Multiple scenarios may not be available • Look at existing monitoring data during critical flow of 80% exceeds (i.e. Low flow) • Each watershed has unique characteristics • Consider downstream needs if local HUC does not respond to elevated TP

28. Integrating Lakes and Rivers by watershed Assessing the impact of WWTPs in each watershed

29. Critical data needs coordination • Flow and water-quality data of rivers and lakes • TP and response variables • Allows for detailed assessment of watersheds • Downstream tracking tool to integrate data • Estimated concentration/load data (Load monitoring unit has already calculated) • Quality TP and flow data from WWTPs • Database already exists • Monitoring has increased for some low flow WWTPS • Spreadsheet/database to document limits • Already exists for Lake Pepin database, DELTA? • Critical when looking at multiple WWTPs

30. One more detail: Averaging periods for limits

31. Annual limits vs monthly limits • Monthly limits • WLA x 2.0 EPA calculated multiplier • WLA = 10 kg/day (3,650 kg/yr) • Limit = 20 kg/day as a monthly average (7,300 kg/yr) • Anticipated performance = 10 kg/day (3,650 kg/yr) • Annual Limits • WLA = 3,650 kg/yr (10 kg/yr) • Limit = 3,650 kg/yr as 12 month moving total or 10 kg/day as 12 month moving average • Anticipated performance: 1,825 – 3,650 kg/yror 5-10 kg/day