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Focused Studies - Sequim Bay

To further assess water quality problems in Washington State, the Washington Department of Ecology conducted a seasonal study of Sequim Bay, a semi-enclosed estuary during 1993. This study was prompted by indications of low dissolved oxygen (DO) in the sediments and water column and possible sewage effluent entering the bay during flood tide. Four monthly surveys were conducted from June through September; sediment and benthic samples were collected in September. Results showed strong seasonal density stratification and high phytoplankton concentrations (> 25 mg/l) throughout the bay, especially in the southern extremity, where DO concentrations as low as 3.8 mg/l were observed. Benthic infauna species composition and distribution showed a marked gradient, with lowest abundance and number of species seen in the southern bay as well.