Watershed Monitoring and Modeling in Switzer, Chollas, and Paleta Creek Watersheds

1. Watershed Monitoring and Modeling in Switzer, Chollas, and Paleta Creek Watersheds Kenneth Schiff Southern California Coastal Water Research Project www.sccwrp.org

2. By The End Of Today • Overview from previous meetings • Review wet season empirical results • Demonstrate success at building watershed models • Assessment guidance so SCCWRP can write final report

3. At Our Previous Meetings • Sediments at the mouth of several urban creeks draining to SD Bay are listed as impaired • - chemistry, toxicity, benthic community • Two questions for this study • What are the loads of COPC to the creek mouth? • How much of the total load deposits in the creek mouth? • Several COPC • Chlordane, PAHs, PCBs, Cu, Pb, Zn, • As, Hg

4. Sources of COPC • Chollas Creek watershed • - Paleta and Switzer Creek watersheds • Runoff directly to the Chollas Creek mouth • Navy, NASSCO • Atmospheric deposition to the creek mouth • San Diego Bay • - tidal inputs

5. Watershed Inputs • Break into two parts • Use combination of empirical data and wet weather modeling • TSS, metals, PAHs • Can we predict changes in loads and concentrations? • Use empirical data • Chlorinated hydrocarbons • Can we detect loads or concentrations?

6. Sampling Design for Wet Weather • Four sites • - North and South Fork Chollas, Switzer, Paleta • Three storms each • - continuous flow data • Pollutograph for model validation • 10 to 12 samples per site event • TSS, metals, and PAH • Flow weighted composites for non-modeled components • - large volume samples for low detection limits

7. Insert maps….

8. * Sampled event * * *

9. (mg/L)

10. Annual Flow Weighted Mean

11. By The End Of Today • Overview from previous meetings • Review wet season empirical results • Demonstrate success at building watershed models • Assessment guidance so SCCWRP can write final report

12. Approach to Building a Watershed Model • Physical data for the model domain • - watershed delineation, stream properties, land use, etc. • Calibrate flow and water quality at small homogeneous land uses • utilize land use data from Los Angeles • Validate flow and water quality at the end of the watershed • - cumulative of all land uses

15. Sampling Design for Wet Weather • Four sites • - North and South Fork Chollas, Switzer, Paleta • Three storms each • - continuous flow data • Pollutograph for model validation • 10 to 12 samples per site event • TSS, metals, and PAH • Flow weighted composites for non-modeled components • - large volume samples for low detection limits

16. Paleta Creek

18. Hydrologic Calibration and Validation • Modeled at hourly time steps • Hourly averages • Hydrographs • Hydrograph simulations • Assess accuracy, bias, precision

19. South Chollas Creek

20. Runoff Volume

21. Peak Flow Mean Flow

22. Water QualityCalibration and Validation • Modeled at hourly time steps • Hourly averages • Pollutographs • - simulations • Event mean concentrations • Accuracy, bias, precision

23. South Chollas Creek

24. South Chollas Creek TSS

25. South Chollas Creek Lead

26. North Chollas Creek Lead

27. Lead Copper Zinc

28. Modeled versus Measured EMCs

29. Long Term Model Runs • Decadal simulation • 1996 to 2006 • All four watersheds • All constituents • Example output • what other simulations do we want?

30. Chollas Ck Switzer Ck Paleta Ck

31. Average Annual Pollutant Loads 1996-2005

32. Percent Landuse Loadings for Copper Switzer Creek Chollas Creek Paleta Creek

33. Load Reduction Scenarios Assumed BMP Storage 22% Reduction 44% Reduction

34. Sources of COPC • Chollas Creek watershed • - Paleta and Switzer Creek watersheds • Runoff directly to the Chollas Creek mouth • Navy, NASSCO • Atmospheric deposition to the creek mouth • San Diego Bay • - tidal inputs

35. Sampling Design for Atmospheric Deposition • Focus was deposition onto the water surface of creek mouth • One site as close to creek mouth as possible • Minimum of 8 sample events • Use surrogate surfaces for metals • Use high volume samplers for organics • Supplement with water samples for diffusion estimates

38. Comparison Among Sources Copper

39. Wet Weather of Summary • Successfully completed wet weather sampling from last season • Empirical data for all constituents at all watersheds • Developed a dynamic model • flow and water quality • Accuracy, bias, and precision near expectations • EMCs versus pollutographs • Modeled long term pollutant loads • - additional model runs?

40. Atmospheric Dry Deposition Summary • Successfully completed dry deposition sampling from last summer • San Diego > other harbors in So Cal • direct dep of metals small relative to wet weather at Chollas Ck mouth • Estimates of dry deposition for organic constituents is nearly finished

41. Upcoming Work • Focused goal on creek mouth modeling • - How much of the total load deposits in the creek mouth? • Designed study plan last year • - SCCWRP and Navy collaboration • Enhance existing Bay model for Chollas Creek mouth • Use our new watershed model for inputs • Increased spatial resolution • Concentrate on particle (and associated COPCs) dynamics • Deposition is mostly a function of settling

42. Wet Season Sampling • Wet weather runoff from Chollas Ck • Large volume samples for particle separation and COPC analysis • Creek mouth sampling for hydrodynamics • Three dimensional plume mapping • Creek mouth sampling for particle dynamics • in situ particle size measurements • Creek mouth sampling for COPCs • Large volume samples for low detection limits

43. Next Steps • Final watershed model runs • Complete atmospheric deposition analysis • Draft Loading Report by March • Creek mouth sampling • one dry weather, two storm events

45. Annual Flow Weighted Mean

46. Percent Landuse Loadings for Lead Switzer Creek Chollas Creek Paleta Creek

47. Percent Landuse Loadings for Zinc Switzer Creek Chollas Creek Paleta Creek