1. 1 Small Tributaries Loading Study #2: Zone 4 Line A, Cabot Blvd. Hayward Year 1 – Draft FINAL report Lester McKee and Alicia Gilbreath Sources Pathways and Loadings Workgroup December 8, 2008 Item #2a

2. 2 Choice of watershed to study TMDL reports encourage further development of loading information Z4LA chosen because it: –Contrasts in size to Guadalupe River –Land use –Climate –Geology and slope Item #2a

3. 3 Location Area: 4.47 km 2 Industrial: 38% Commercial: 26%Residential: 33% Item #2a Sampling location

4. 4 Channel Item #2a

5. 5 Field equipment Item #2a

6. 6 Field sampling for contaminants Item #2a

7. 7 Measurement of discharge Item #2a

8. 8 Results – Rainfall and runoff 21 storm events cumulative rainfall = 270 mm (10.6 in) 1.6 year return %77 % of average (45 y record at 50dly to the south Item #2a

9. 9 Results – Suspended sediment Item #2a

10. 10 Scatter plots Item #2a

11. 11 Spearman partial correlations – effect of SSC removed Item #2a Hg not correlated with Cr, Ni, Se despite common geologic origins

12. 12 Comparisons to CA soils Item #2a 5 0 7%

13. 13 Results – Trace organics All <10% PCB 110/115, 129/138/160/16 3, 153/168, 180/193 Item #2a

14. 14 PBDEs Item #2a BDE 47, 99, 209 (73-88%)

15. 15 Loads of Organics Organic carbon: <1% SSC (Guadalupe 0.5-1.1%) PCB concentrations normalized to sediments (0.13 mg/kg) were 10x greater than found in the Bay PBDE loads were 2.8 x PCB loads PAH loads, despite abundant sources lower than PCBs/PBDEs, DDT and similar to chlordanes Item #2a

16. 16 Z4LA concentration comparisons Local concentration data –Guadalupe, Coyote, San Pedro storm drain Hg: Z4LA = Coyote within range of San Pedro << Guadalupe PCB: Z4LA = Guadalupe >Coyote (*dry year) PBDE / DDT / chlordane, dieldrin similar trends to PCBs Item #2a

17. 17 MeHg SSC proxy to flow Dilution during high flows More production during low flows Similar particle concentrations to wetlands (Heim et al., 2007) Item #2a

18. 18 Which and how many watersheds should be sampled? Area (km 2 ) SS (t/km 2 ) Hg MeHg AgCd Cr Cu Ni Pb Zn PCB PBDE DDT Chlordane Dieldrin Hayward Urban watershed (Z4LA WY 2007)4.5245.60.168.0431,4002,5001,800 21,0003.29.03.71.3 0.30 Guadalupe River (WY 2004)23636640.08812.6412,7123,0085,0852,20312,7123.36.73.32.5 0.26 Statistically significant?yes maybeno yesnoyesnoyesno maybe no Export of POC during climatic years with ~70% mean annual runoff (units: micrograms per square meter (µg/m 2 ) unless otherwise specified San Francisco Estuary Institute Item #2a

19. 19 Regional loads estimates (Flow method)

20. 20 Regional loads estimates (Sediment method) Discount estimate based on Davis et al. (2000) sediment load: we are quite certain it is too low. Hg: 84 – 91 kg is less than TMDL estimate (160 kg) PCB: 13 – 26 kg is similar to TMDL estimate (20 kg) PBDE: 37 – 79 kg is similar to Oram et al (2008) estimate (60 kg)

21. 21 Recommendations Given Z4LA was sampled under dry conditions in the first year sampling continue for either 3-4 years or until storms of <5 year return are sampled Given regional load estimates are crude at best, effort should be made to: –Develop regional modeling capability –Gather sample a greater variety of land types specifically as input into models Improve regional data set for MeHg and HgR in the context of “high leverage watersheds” Given the unexpected similarity between watersheds for the trace organics, effort should be made to reject the hypothesis that imperviousness is more important than sources –An alternative hypothesis is that watershed scale is masking the source issue