1. Comparative Analysis of Loads of Mercury in Coyote Creek and Guadalupe River Lester McKee RMP SPLWG Chair San Francisco Estuary Institute lester@sfei.org

2. Acknowledgements and Data Sources Coyote Creek USGS discharge –WY 1999 – 2006 (ongoing) USGS suspended sediment –WY 2005 –WY 2006 Regional Board TMDL laboratory funding ($10k) –WY 2005 PCB, PBDE, HgT, SSC, organic carbon Data –SFEI field team able to grab 7 samples during wading stage only during breaks from Guadalupe R. sampling Guadalupe River USGS discharge –WY 1929 – 2006 (ongoing) USGS/SFEI suspended sediment –WY 2003 – 2006 (ongoing) Funding –WY 2003 CEP –WY 2004 CEP / RMP –WY 2005 RMP / SCVWD / USACE / SCVURPPP Data –HgT, HgD, MeHgT, MeHgD, Bedload HgT

3. Land Use Comparisons Area (below Dams)IndustrialCommercialResidential Open/ Agricultural Coyote Ck. (km 2 )335151683222 Percentage (%)100452566 Guadalupe R. (km 2 )23630 13738 Percentage (%)10013 5816

4. Field Locations Coyote Ck. at Hwy 237 USGS 11172175 Area: 826 km 2 Guadalupe R. at Hwy 101 USGS 11169026 Area: 414 km 2 Guadalupe R. Coyote Ck.

5. Methods Sampling Location USGS Gage Shelter

6. Results – Coyote Creek Sample NumberDate / time Suspended Sediment (mg/L) Total Mercury (ng/L) CC4012/7/04 9:05-40 CC7012/27/04 12:22 5111 CC8012/31/04 14:51 22854 CC901/7/05 8:38 7721 CC911/7/05 16:35 11039 CC921/9/05 11:55 7018 CC1001/11/05 17:04 33859 CC100 Dup1/11/05 17:06 33557

7. Total Mercury v Suspended Sediment (All data)

8. Total Mercury v Suspended Sediment (Runoff from Upper and Lower Watershed)

9. Loads Calculation Methods (WY 2005) USGS 15 minute discharge USGS 15 minute SSC estimates from GCLASS based on rating relationships between flow and about 100 real measurements of SSC Regression between instantaneous SSC and Total Mercury concentrations –All data –Separate regressions for water derived from Lower and Upper watershed

10. Maximum Daily and Flood Loads Total Mercury Wet Season (Oct 2004 - Apr 2005) (kg)2.5 Maximum Daily (2/15/05) Load (kg)0.23 Load (% wet season)9 Largest Flood (2/15/05 14:30) Load (kg)0.28 Load (% wet season)12

11. Why so little during the largest flood?

12. Results – Monthly Loads 2004 2005 OctNovDecJanFebMarAprTotal Flow (Mm 3 )3.31.34.96.910.313.17.547 Total Mercury (kg)0.40.020.50.20.70.60.12.5

13. Estimated Average - Methods Average = 41 Mm 3 Measured Estimated

14. Estimated Average Coyote Loads Using the range in flow experienced from WY 1971 to WY 2006 we estimate the following: Flow (Mm 3 ) Total Mercury (Estimated using separate regressions) (kg) Total Mercury (Estimated using A single regression) (kg) Minimum2.00.001 Maximum173.95544 Average40.676

15. Coyote Creek versus Guadalupe River Coyote Creek HgT (ng/L) HgT (mg/kg) Load (kg) Export (µg/m 2 /yr) 11-580.17-0.36 7 (0.001 - 55)20 Guadalupe River HgT (ng/L) HgT (mg/kg) Load (kg) Export (µg/m 2 /yr) DL - 18,6730.41 - 95 140 (0.03 - 1,000)600

16. Particle Concentrations Coyote Ck, Guadalupe R. and Sacramento R.

17. Applicable Management Questions B. Loads of mercury and methylmercury Are current estimates about loading to San Francisco Bay from watersheds, wastewater treatment facilities, and atmosphere valid? What is the contribution of atmospheric deposition to urban storm water?

18. Applicable Management Questions C. Processes of mercury methylation What is the relative bioavailability of mercury entering the Bay from various loading sources (e.g., wastewater treatment facilities, atmosphere, urban runoff, tributaries, newly eroded historic sediments, etc)?

19. Applicable Management Questions D. Given what we currently understand about processes, loads, and impacts (Sections A, B, and C), what are the management implications? Given that rivers, creeks, and storm drains discharge methyl mercury, what can be done to manage production in the watershed and urban environments, and to manage downstream impacts as it passes through wetlands to the Bay margin and Bay?