Water quality in the Puget Sound basin, Washington and British Columbia, 1996-98

Puget Sound basin streams during 1995-98 met most guidelines and criteria. Seventy-four manmade compounds were detected and different mixtures linked to land use. Urban expansion into forested areas is changing stream habitats--urban and agricultural streams are warmer and support less diverse insect populations than streams in forested areas. Elevated nitrate concentrations and the presence of manmade organic compounds indicated shallow ground water in urban and agricultural settings is vulnerable to contamination.