Modeling Status & Criteria Development Andy Thuman

1. Modeling Status &Criteria DevelopmentAndy Thuman Murderkill River StudyMarch 2, 2010

2. Data Needs to Complete Modeling • Algal production study data • Algal production data by station/date (raw data also) • Areal (depth averaged) & volumetric (by light level) • Marsh loading data • Dissolved & particulate raw data w/ tide info • Loading summary by sampling event • Wetland inundation data • Wetland area by river mile & for Webbs Marsh • At high tide or based on tidal species distribution

3. Marsh InfluencesWebbs Landing 2008 Continuous Data

4. Modeling Overview (Current Status) • HSPF model flow calibration/validation • Time-series • HSPF water quality calibration/validation • Time-series for 2007-2008 • Still need to add in septic loads and adjust groundwater concentrations • Continue calibration/validation work on chl-a levels in lakes/ponds

5. Flow Calibration/Validation (2007-2008)

6. McGinnis Pond (206461)

7. Coursey Pond (206451)

8. McGinnis Pond (206461)

9. Coursey Pond (206451)

10. Where we are now & going to be? • Data collection has been used to define: • Marsh loads/impacts • Algal production (role of phytoplankton) • Sediment role in nutrient/DO dynamics • Develop water quality models of watershed/river • Use calibrated/validated models to: • Determine load reductions required to meet DO standards in the tidal river • Determine DO levels due to natural background loadings (upstream, marsh, bay)

11. What do we do next? • Are the load reductions feasible to meet DO standards? • Are the low DO levels due to natural background conditions? • DNREC DO & nutrient standards: • Daily average >= 5 mg/L, min of 4 mg/L • Policy is to minimize nutrient input from PS & NPS as determined on a site-specific basis • ** Use DO as response variable for nutrient effect since no nutrient endpoint criteria (e.g., chl-a) **

12. EPA Proposed Nutrient Criteria for FL • Streams: • No strong cause-effect relationships to biological health (SCI) or benthic algae • Select biologically healthy reference streams & determine 75th percentile N & P concentrations • No cause & effect • Lakes: • Set nutrient response criteria (chl-a based on different types of lakes) • But then determine N & P concentrations from nutrient-algal relationships

13. EPA Proposed Nutrient Criteria for FL

14. EPA Proposed Nutrient Criteria for FL • Estuaries: • Definitely no cause & effect • Assume all FL estuaries are nutrient impaired • Use SE nutrient loading model (SPARROW) to determine current & “pristine” nutrient loads • Set protective TN load between the two loads • Result is 50% reduction in man-made loads • FDEP is currently requesting assistance in proposing alternate estuary criteria to EPA • Based on cause & effect, some instances current loads are safe since not all estuaries are impaired

15. What do we do next? • If DO naturally below the WQS: • Develop site-specific DO standard (e.g., 90% of time > 2 mg/L, recruitment curve) • Determine natural background DO & allow some additional level of change for man-induced sources (e.g., 0.1 mg/L or 10% of natural DO)

16. Site-Specific Water Quality Criteria • Based on scientifically reasonable method • Murderkill River Study • Use DO as response variable for nutrient loading & for developing SSAC for DO • Set nutrient loads for Murderkill River to meet the DO SSAC developed through TMDL process

17. Andrews Lake (206071)

18. Spring Creek, Pratt Branch (206641)

19. Murderkill River at Confluence of Black Swamp Creek (206011)

20. McColley Pond (206361)

21. Browns Branch at Milford Harrington Hwy. (206041)

22. Browns Branch at Killens Pond (206051)

23. Andrews Lake (206071)

24. Spring Creek, Pratt Branch at Canterbury Rd. (206641)

25. Murderkill River at Confluence of Black Swamp Creek (206011)

26. McColley Pond (206361)

27. Browns Branch at Milford-Harrington Hwy. (206041)

28. Browns Branch at Killens Pond Rd. (206051)