Advances in Understanding Pollutant Mass Loadings Lester McKee Jon Konnan, Richard Looker, Nicole David, Jay Davis Article on Page 77 of the Pulse

Why Measure Loadings? Fish consumption advisories since 1993 –San Francisco Bay is listed as impaired for a range of contaminants Initially loadings information was generated to develop TMDL project reports written by the Water Board –More loadings information –Measurement of progress towards targets

What are the priority contaminants? SubstancePriority Mercury and PCBsTop Polybrominated diphenylethers (PBDEs)High Current use pesticides (pyrethroids), dioxins, selenium, OC pesticides, copper, nickel, PAHsMedium Silver, arsenic, cadmium, chromium, lead, zinc, organophosphate pesticides, nutrientsLow

What are the Main Sources and Pathways? Guadalupe River Urban StormwaterIn-Bay contaminated sites Focus is on the larger pathways that are deemed potentially controllable

Sacramento River Guadalupe River Zone 4 Line A What Stormwater Loading Studies are ongoing?

Sacramento River at Mallard Island near Pittsburg

Concentration on particles (Low – moderate flow)

Concentration on particles (Large storms)

Mean = 1 million metric t Loadings per year - Sediment Journal of Hydrology: McKee et al., 2006

Loadings per year – Mercury Mean = 210 kg ET&C: David et al., in review

Loadings per year - PCBs Mean = 9.6 kg

Guadalupe River at Hwy 101 in San Jose

Mercury on Particles

PCBs on Particles Urban stormwater Non-urban stormwater

Loadings per year - Sediment Mean = 14,000 metric t

Loadings per year - Mercury Mean = 130 kg Methylmercury <<1%

Loadings per year - PCBs Mean = 0.9 kg PBDEs = 2.5x greater

Zone 4 Line A Tributary at Cabot Blvd. in Hayward

Loadings normalized per unit area per year Area (km 2 ) Suspended Sediment (t/km 2 ) Total Mercury (  g/m 2 ) Methyl- Mercury (  g/m 2 ) Sum of PCBs (  g/m 2 ) Sum of PBDEs (  g/m 2 ) DDT (  g/m 2 ) Z4LA (WY 2007) Guadalupe River (WY 2004) Statistically different?Yes No

What have we learned? Mercury

What have we learned? PCBs

Mercury Which watersheds are most contaminated? What are the loadings from specific watersheds and the region as a whole –Currently based on sediment Hg concentrations and out-dated estimates of regional sediment loads Little information on mercury speciation –Methylmercury –Reactive mercury Remaining Questions and Progress

PCBs Little information on loadings from small heavily industrialized watersheds –Mainly near the Bay margin –Focus on “old industrial” Which watersheds are most contaminated? What are the sources and processes of release? Remaining Questions and Progress

PBDEs and OC pesticides –One box model paper published in Environment International (Oram et al 2008) –Penta and Octa banned – when will the loads go down - will the Bay recover? Dioxins and pyrethroid pesticides –No information on urban loadings –Little to no information on other pathways Selenium, Copper, Nickel, PAHs –Not recently discussed

All contaminants Are there “high leverage” areas or processes on the Bay margin where contaminants impact the base of the food web What is the linkage between watershed loadings and “hotspots” or “high leverage” areas on the Bay margin What are the remaining questions?

Small Tributaries Loadings Strategy –Being developed now Mercury Strategy (page 4 of the Pulse) –First strategy to be developed Dioxin Strategy –Priorities vary by stakeholder – very expensive so still debate over funding Modeling Strategy –Being developed now Planning efforts to prioritize and address data gaps

1) Impairment Which are the “high-leverage” small tributaries that contribute most to Bay impairment? 2) Loading What are the concentrations and average annual loads of pollutants of concern from small tributaries? 3) Trends How are concentrations or loads of pollutants of concern from small tributaries changing on a decadal scale? 4) Support for Management Actions What are the projected impacts of management actions and where should management actions be implemented? Small Tributaries Loading Strategy A three page document that includes: Key questions and priorities Guiding principles A timeline Recommended methods

Summary Our understanding of pollutant mass loads has changed considerably –We now have accurate measurements of loads in three watersheds But there are still many questions Through time the needs for information are becoming more explicit and the RMP is adapting to new needs –Constant re-evaluation of the management questions –5-year plans for the workgroups and the program as a whole –Focus strategy documents (contaminant or issue specific)

Acknowledgements Mercury labs –MLML –UCSC –Brooks Rand Trace organics lab : AXYS Sediment studies –USGS –USDA –RiverMetrics Field staff –SFEI –UCSC –Water Board