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Puget Sound Marine Monitoring

The best decisions are based on Sound information

For questions about the King County Puget Sound Marine Monitoring Program, please contact

Routine Marine Monitoring Programs

photo of scientist with sampling equipment photo of scientist sampling beach water column photo of scientist with sediment sampling equipment photo of scientist with digging for shellfish photo of scientist with digging for shellfish

The King County Department of Natural Resources and Parks has a long history of environmental monitoring in Puget Sound. As part of an ongoing effort to maintain and improve Puget Sound's water quality, the King County Wastewater Treatment Division oversees regional sewerage collection, treatment processes, and disposal systems that discharge wastewater to the Central Puget Sound Basin and waters flowing into the Sound. King County's Marine and Sediment Assessment Group supports a comprehensive long-term marine monitoring program that assesses water, sediment, and tissue quality in the Central Puget Sound Basin on behalf of and in coordination with the Wastewater Treatment Division.

King County’s routine marine monitoring program is part of an intergovernmental monitoring effort, the Puget Sound Assessment and Monitoring Program (PSAMP), with the County's program focusing primarily on water quality within King County’s borders. The main distinction between other PSAMP programs and King County’s monitoring program is that the County has a larger number of stations within a concentrated area, which are targeted near wastewater treatment plant discharges. Although other agencies have monitoring stations within King County, the stations do not overlap with the County's stations, which allows a broader area of Puget Sound marine waters to be monitored.

The goal of the routine monitoring program is to identify sources of water pollution, provide water quality information for management decisions, and evaluate status and trends of marine waters within King County. To meet this goal, the objectives of the monitoring program are to:

  • implement a long term program to characterize water quality within King County;
  • comply with NPDES monitoring requirements;
  • gather sufficient data to determine both short and long term water quality conditions;
  • determine physical and chemical dynamics that influence water quality;
  • support coordinated regional monitoring effores; and
  • collect scientific data of high quality to inform water quality management decisions.

King County’s routine marine monitoring program includes five major components.

  • The offshore water column monitoring program assesses both nonpoint and point source pollution in nearshore and offshore environments, as well as assessing ambient (background) conditions. Water column measurements and samples are collected monthly to evaluate physical, chemical, and biological parameters throughout the water column.
  • The marine beaches monitoring program water quality at King County’s marine beaches by collecting monthly samples for analysis of bacterial and nutrient concentrations.
  • The subtidal sediment monitoring program measures chemical concentrations in ambient Puget Sound sediments, with a focused effort on sediment quality in Elliott Bay. Subtidal sediment samples are analyzed for trace organic compounds, metals, and conventional parameters.
  • The shellfish monitoring program uses butter clams as a bio-indicator of nearshore water and sediment quality by collecting semiannual measurements of chemical concentrations in their soft tissues. Butter clam tissues are analyzed for trace metals and brominated flame retardants.
  • The marine moorings are automated, high-frequency, water quality data collection systems that allow continuous measurements of physical, chemical, and biological water quality parameters as well as meteorological parameters.