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Lester McKee, John Oram and, Jon Leatherbarrow Sources Pathways and Loadings Workgroup

San Francisco Estuary Institute. Item #3. PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries Loads. Lester McKee, John Oram and, Jon Leatherbarrow Sources Pathways and Loadings Workgroup November 13 th 2006. San Francisco Estuary Institute.

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Lester McKee, John Oram and, Jon Leatherbarrow Sources Pathways and Loadings Workgroup

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  1. San Francisco Estuary Institute Item #3 PCB and PBDE Loads in Coyote Creek:Conceptual models and Estimates of Regional Small Tributaries Loads Lester McKee, John Oram and, Jon Leatherbarrow Sources Pathways and Loadings Workgroup November 13th 2006

  2. San Francisco Estuary Institute Item #3 History • USGS discharge • WY 1999 – 2006 (ongoing) • USGS suspended sediment data • WY 2005 • WY 2006 • Regional Board TMDL laboratory funding ($10k) • WY 2005 PCB, PBDE, HgT, SSC, organic carbon • SFEI field team able to grab 7 samples during wading stage only during breaks from Guadalupe R. sampling

  3. Coyote Ck. at Hwy 237 USGS 11172175 San Francisco Estuary Institute Item #3 Field Location Guadalupe R. at Hwy 101 USGS 11169026

  4. Sampling Location USGS Gage Shelter Item #3 Methods

  5. San Francisco Estuary Institute Item #3 Methods • Grab samples from mid depth at wading stages • Regression between instantaneous SSC and PCB/PBDE concentrations • USGS 15 minute discharge • USGS 15 minute SSC estimates from GCLASS

  6. San Francisco Estuary Institute Item #3 Results - Concentrations * Based on annual load

  7. San Francisco Estuary Institute Item #3 Regression EstimatorsPCBs

  8. San Francisco Estuary Institute Item #3 Regression EstimatorsPBDEs

  9. San Francisco Estuary Institute Problem • How to we apply the two populations of data (regression estimators) to published USGS daily sediment records? • Solution: Obtain 15 minute records • Errors • USGS accurately measures 15-minute discharge • USGS only estimates 15 minute SSC based on rating relationships between flow and about 100 real measurements of SSC

  10. San Francisco Estuary Institute Item #3 Results - Loads

  11. San Francisco Estuary Institute Item #3 Historic Flow Measured Estimated Average = 41 Mm3

  12. San Francisco Estuary Institute Item #3 Average Load Estimate – MethodPCB

  13. San Francisco Estuary Institute Item #3 Average Load Estimate – MethodPBDE

  14. San Francisco Estuary Institute Item #3 Estimated Average Loads • Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following:

  15. San Francisco Estuary Institute Item #3 Guadalupe R. Estimate of Average Loads

  16. San Francisco Estuary Institute Item #3 Methods • Develop a regression estimator using monthly flow and monthly load • Obtain historic monthly flow records for the period 1971 – 2006 • Estimate monthly loads • Calculate average

  17. San Francisco Estuary Institute Item #3 Guadalupe Regression Estimators

  18. San Francisco Estuary Institute Item #3 Estimated Average Loads • Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following:

  19. San Francisco Estuary Institute Item #3 Coyote – Guadalupe ComparisonAre the estimates reasonable? (mg/kg)

  20. San Francisco Estuary Institute Item #3 Estuary Interface Pilot Study Leatherbarrow et al., 2002

  21. San Francisco Estuary Institute Item #3 Estimating Total Regional Small Tributaries Loads:Extrapolation methods in the absence of hydrologic models

  22. San Francisco Estuary Institute Item #3 Methods(PCBs and PBDEs) 1. Add Guadalupe and Coyote estimated average annual loads together and scale by area a) Total area b) Excluding area above reservoirs 2. Assume most load is associated with urban area and scale the sum of Guadalupe and Coyote estimated average annual loads by an urban land use factor.

  23. San Francisco Estuary Institute Item #3 Methods(PCBs only) 3. Use the sum of Coyote+Guadalupe average loads to scale (calibrate) land use specific estimates of PCB export derived by an extensive literature review and mass balance model (SFEI Prop 13). Apply these to land use statistics below reservoirs for the Bay Area (Davis et al., 2000).

  24. San Francisco Estuary Institute Item #3 Methods(PBDEs only) 4. Scale PBDE loads to PCB loads using a ratio of 3:1

  25. San Francisco Estuary Institute Item #3 Statistics for Calculations

  26. San Francisco Estuary Institute Item #3 Prop 13 export estimates(Ref: Mangarella et al., 2006)

  27. San Francisco Estuary Institute Item #3 Scaled (Calibrated) Unit Exports

  28. San Francisco Estuary Institute Item #3 Results Annual Average Loads Estimates for Total Bay Area Small Tributaries * Assumed - 50% error + 100% error based author’s hypothesis that Coyote and Guadalupe are not representative of other Bay Area urban watersheds due to large size and relatively low connectivity / drainage density ** Authors judgment

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