A Cooperative Program Managed and Administeredby the

San Francisco Estuary Institute

1995 Annual Report

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Regional Monitoring Program for Trace Substances

Printed on recycled paper

Regional Monitoring Program Participants

Municipal Dischargers Industrial DischargersCity of Benicia C & H SugarBurlingame Waste Water Treatment Plant Chevron USACity of Calistoga Dow Chemical CompanyCentral Contra Costa Sanitation District EXXON Company, USACentral Marin Sanitation Agency General ChemicalDelta Diablo Sanitation District Pacific Refining CompanyEast Bay Dischargers Authority Rhone-PoulencEast Bay Municipal Utility District Shell Martinez RefiningFairfield-Suisun Sewer District TOSCO Refining CompanyCity of Hercules UNOCAL-San Francisco RefineryLas Gallinas Valley Sanitation District USS-POSCOMillbrae Waste Water Treatment PlantMountain View Sanitary District Cooling WaterNapa Sanitation District Pacific Gas & ElectricNovato Sanitation DistrictCity of Palo Alto Storm WaterCity of Petaluma Alameda Countywide Clean Water ProgramCity of Pinole CALTRANSRodeo Sanitary District Contra Costa Clean Water ProgramCity of Saint Helena Fairfield-Suisun Sewer DistrictCity and County of San Francisco Marin County Stormwater PollutionCity of San Jose/Santa Clara Prevention ProgramCity of San Mateo City and County of San FranciscoSausalito-Marin City Sanitation District San Mateo County Stormwater PollutionSewerage Agency of Southern Marin Prevention ProgramSan Francisco International Airport Santa Clara Valley Nonpoint Source PollutionSonoma County Water Agency Control ProgramSouth Bayside System Authority Vallejo Sanitation and Flood Control DistrictCity of South San Francisco/San BrunoCity of Sunnyvale DredgersMarin County Sanitary District #5, Tiburon Benicia Terminal IndustriesUnion Sanitary District Port of OaklandVallejo Sanitation and Flood Control Port of Redwood CityWest County Agency Port of RichmondTown of Yountville Port of San Francisco

US Army Corps of EngineersUS Navy, Western Division

Executive Summary

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The 1995 Regional Monitoring Program(RMP) Annual Report includes monitoringresults from the Base Program, Pilot and SpecialStudies, and summary and perspective articlescontributed by RMP investigators and otherscientists.

The purpose of the RMP is to provide infor-mation on the status and trends of contamina-tion in San Francisco Estuary water, sediment,and bivalve tissue, and to assess the potential forbiological effects from exposure to those contami-nants. The objectives, background, and rationalefor the RMP are described in the Introduction(Chapter 1).

The 1995 RMP Base Program was essen-tially the same as in 1994. Water monitoring wasconducted in February, April, and August at 24stations throughout the Estuary. Aquatic bioas-says were conducted in February and August at13 of those stations. Sediment monitoring wasconducted in February andAugust at all 24 stations, andsediment bioassays wereconducted at 12 of those sta-tions. Bioaccumulation ofcontaminants by transplantedbivalves was monitored at 15stations during two 90 day sampling periods:January to April and July to September.

Pilot Studies on benthic fauna and tidalwetlands were conducted and Special Studies ontrends in trace elements and development ofsediment indicators were also included.

Water MonitoringWater Quality

Monthly water quality monitoring wasconducted by the US Geological Survey (USGS).This component of the RMP describes waterquality (e.g., salinity, suspended sediments,dissolved oxygen, etc.) throughout the Estuary(Chapter 2). Their monthly samples providesupplementary information about water qualityat the times between RMP Base Program sam-pling periods.

In general, the patterns of salinity in 1995reflected the effects of river flow on the distri-bution of dissolved constituents. Salinitydecreased from the Golden Gate into northernSan Francisco Estuary during most of the year,whereas salinity in the South Bay was usuallyhomogeneous. This reflects the role of Deltaoutflow as a continual source of freshwater intothe North Bay. The North Bay salinity gradientchanged rapidly in response to changing flowsduring the year. Salinity in the South Bay maybe diluted by freshwater arriving from thenorthern connection to Delta-derived flows, aswell as by runoff from the local watershed.

The patterns of total suspended sediments(TSS) showed that strong freshwater flowsdeliver new sediments to the Estuary. This isimportant because concentrations of TSS aredirectly related to concentrations of manycontaminants. TSS was generally lowest in theCentral Bay, far from the riverine supplies of

sediments and far fromthe shallow habitatswhere wind-waveresuspension creates highturbidity.

The potential forbiological transformations of dissolved chemi-cals in water into organic forms was monitoredby measuring chlorophyll. Phytoplanktoncomprise one of the largest components of livingbiomass in San Francisco Bay. Phytoplanktonbiomass, as measured by chlorophyll, wasusually low in the Bay-Delta. However, duringspring blooms in the South Bay, biomassincreased rapidly. During these blooms, dis-solved inorganic carbon, nitrogen, phosphorus,and silicon, as well as some trace elements(cadmium, nickel, zinc) were removed fromwater and transformed into organic forms. Asthe 1995 RMP sampling in April occurred at theend of a two-month bloom, reduced concentra-tions of those dissolved trace elements wereobserved in the South Bay samples (pages 15,20, and 23).

Executive Summary

Salinity patterns reflected theeffects of river flow on dissolvedconstituent distributions.

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Regional Monitoring Program 1995 Annual Report

Contaminants in Water

Different contaminants exhibited differentpatterns of distribution in the Estuary. In 1995,overall, the South Bay had the highest concen-trations of both trace elements and traceorganic contaminants (Chapter 2). However,concentrations of dissolved copper and nickelwere much higher at the Petaluma Riversuggesting the presence of a source of theseelements near that station. The distribution oftotal (or near-total) concentrations of chro-mium, copper, lead, mercury, nickel, silver, andzinc reflected the distribution of TSS, with thehighest concentrations in the Southern Sloughsand at the Petaluma River, intermediateconcentrations at the North-ern Estuary and Riverstations, and lowest concen-trations in the Central Bay.Analysis by USGS showedthat seven trace elementswere well-correlated with TSS in the Estuary(page 53). Concentrations of trace organiccontaminants that tend to be associated withparticles, such as PAHs, PCBs, DDTs, andchlordanes, also displayed the same basicpattern as TSS; the highest concentrationsoccurred in the South Bay, lower concentrationsin the Central Bay, higher concentrations in theNorthern Estuary, and intermediate concentra-tions in the Rivers. Most dissolved trace organiccontaminants, including PCBs, chlordanes,DDTs, HCHs (hexachlorocyclohexanes) anddiazinon, were elevated in the South Bayrelative to other reaches of the Estuary, withconcentrations progressively decreasing fromCoyote Creek to the Golden Gate. Diazinonconcentrations were highest at nearly allstations in February, reflecting its seasonalusage.

Seasonal variation was also observed inmany other contaminants. Total arsenic, near-total cadmium, and dissolved silver, arsenic,cadmium and PAHs were highest in August.Total concentrations of chromium, copper, lead,mercury, nickel, silver, PAHs, PCBs, chlor-danes, and DDTs tend to be associated with

particles and were often highest in April,coinciding with high concentrations of TSS.

Long-term trends in total trace elementconcentrations were examined in detail usingdata collected from April 1989 to April 1995under the RMP and Pilot Studies that precededthe RMP (pages 7884). There were no obviousincreasing or decreasing trends in trace ele-ment concentrations. For certain persistenttrace organics, the long-term rate of decline inconcentrations appears to be very slow. Data forwater organics from the mid-1970s and early1980s compared to RMP data showed thatconcentrations of PCBs have generally notdeclined appreciably, although they have been

been banned for decades.Neither have PAHs declined, ascontinuous sources still exist.DDTs and chlordanes appear tohave declined since beingbanned in the 1970s.

Comparisons to Water Quality Objectivesand Criteria

Concentrations of many contaminants wereabove applicable water quality objectives orcriteria. Of the 10 trace elements measured,concentrations of chromium, copper, lead,mercury, and nickel were above applicablewater quality objectives or criteria on one ormore occasions. Copper, mercury, and nickelwere most frequently above objectives orcriteria. PCBs were always above EPA criteria,PAHs were frequently above criteria, andDDTs, chlordanes, dieldrin, and diazinon wereoccasionally above water quality objectives orcriteria. The stations with the largest numberof concentrations above guidelines were CoyoteCreek, the Dumbarton Bridge, and the Peta-luma River. The overall pattern of exceedanceswas very similar in 1994 and 1995.

In water, the South Bay hadthe highest concentrations ofmost trace elements andtrace organic contaminants.

Copper, mercury, and nickel were mostfrequently above water quality objectives orcriteria. PCBs were always above criteria,PAHs were frequently above criteria, andDDTs, chlordanes, dieldrin, and diazinon wereoccasional