The National Coastal Assessment (NCA) of US EPA conducted the first probability based assessment of the condition of estuarine intertidal wetland resources of the West Coast of the U.S. in 2002. The study results constitute a baseline estimate of condition of coastal resources that will allow determination of trends in future condition. The dominant types of estuarine intertidal habitat varied among the three states, although unvegetated sand or mud flats were the dominant habitat types for all three states. Shellfish beds (oysters), gravel bottom, and intertidal seagrasses were recorded only in Washington and Oregon. San Francisco Bay and the rest of California tended to have finer sediments, higher Total Organic Carbon, higher concentrations of sediment nitrogen and phosphorus, and higher average Effects Range-Median Quotient (ERM-Q) values than estuarine intertidal areas in Washington and Oregon. Levels of sediment contamination west wide were low, with only 0.21% of the intertidal area of West Coast estuaries having >5 exceedances of Effects Range Low (ERL) concentrations. The single most abundant polychaete in the West Coast intertidal was a nonindigenous species introduced from the Northeast Atlantic. Vegetation was present at two thirds of the sites sampled and included 28 emergent macrophytes, 2 seagrasses, and macroalgal taxa. Findings confirm results from previous National Coastal Assessment studies of west coast estuaries that have indicated sediment contamination issues are limited in extent, but that west coast estuaries have been broadly invaded by nonindigenous species.

"September 2007." "EPA 620-R-07-002." Cover title. Includes bibliographical references (pages 60-62).