Offshore Water Quality

King County’s marine environment supports a rich ecosystem that ranges from microscopic plankton to iconic orcas. These creatures depend on an ecological balance that is threatened by environmental challenges like pollution, habitat degradation, and climate change. To better understand and safeguard the health of Puget Sound, King County monitors offshore waters by conducting laboratory analysis of water quality. We look at parameters such as bacteria and nutrients and take physical, chemical, and biological measurements with a multi-sensor device called a CTD (conductivity, temperature, and depth) at 14 offshore locations in the Central Basin and 4 locations in the marine water-influenced area of the Duwamish River. These locations include sampling near wastewater outfalls as well as sampling located further away from outfalls. We collect these samples twice monthly during most of the year (monthly in December and January).

The laboratory and CTD data we collect offer insights into Puget Sound’s ecosystems, such as the distribution of nutrients and amount of dissolved oxygen in the water, the influence of regional climate and freshwater input on water properties, and the influence of incoming water from the Pacific Ocean. These data allow scientists to track changes and make informed decisions for ecosystem management and conservation.