Skip to main content

Marine Moorings

King County’s marine moorings continuously measure water quality parameters, offering insight into how Puget Sounds ecosystem is changing in real time. These autonomous data-gathering platforms help identify environmental changes in the previous hour to the previous several years, filling in data when we are unable to sample for the offshore monitoring program.
A marine buoy in Puget Sound.
If data from the offshore monitoring program is like a high-quality landscape photograph, moorings are like a video camera pointed at a single bush. While moorings don’t capture all of the details around them, they continuously monitor how that bush is changing, tracking what’s climbing through the branches, and capturing the small events that happen between photographs.

Marine moorings continuously measure data in a single location, providing updated water quality data every 15 minutes. This automated sampling fills in gaps between our offshore monitoring program’s sampling events and provides real-time updates on current conditions. Moorings provide a robust data record that allows scientists to track how water quality parameters are changing over short and long time scales, from hour-by-hour to year-by-year, with minimal effort from field scientists. 

King County currently maintains four active moorings in Puget Sound’s Central Basin. In November 2007, we partnered with the Seattle Aquarium to deploy its first automated water quality data collection system in Elliott Bay. Three additional systems are currently deployed: a piling-mounted system at Dockton Park in outer Quartermaster Harbor (Vashon Island), a dock-mounted system at the Yacht Club in inner Quartermaster Harbor, and a buoy-mounted system off Point Williams in Central Puget Sound.

More Information

The goals of this monitoring are to: 

  • Collect and maintain a long-term dataset of conditions within Puget Sound’s Central Basin. 

  • Characterize water quality within King County’s marine ecosystem. 

  • Evaluate spatial and seasonal variation of water quality parameters from year-to-year. 

  • Determine physical, chemical, and biological dynamics that influence water quality. 

  • Assess long-term trends in water quality parameters. 

  • Monitor water quality near King County marine wastewater outfalls. 

  • Support regional marine monitoring and modeling efforts. 

  • Evaluate data with regard to Washington State water quality guidelines. 

Sensor Range Resolution Accuracy Mooring
HC-EP Temperature (°C) -5 to 45 0.0001 ± 0.002 All
HC-EP Conductivity (mS/cm) 0 to 70 0.001 0.003 All
HC-EP Salinity (psu) 0 to 42 0.001 0.005 psu All
HC-EP Dissolved Oxygen (mg/L) 0 to 25 0.007 ± 0.1 mg/L or 2%, whichever is greater All
HC-EP Turbidity (NTU) 0 to 3,000 0.06 - 0.17 ±1% All
Sonde pH (HC-EP) 0 to 14 0.01 ± 0.1 All
HC-EP Chlorophyll (µg/L) 0 to 400 0.007 -0.037 ±3% All
pH (SeaFET, recalculated, total scale) 6.5 to 9.0 0.004 ± 0.02 Point Williams, Quartermaster Harbor Yacht Club
pH initial (not recalculated) 6.5 to 9.0 0.0001 Requires validation Point Williams, Quartermaster Harbor Yacht Club
Nitrite+Nitrate-Nitrogen (mg/L) 0.007 to 56 0.01 ± 0.028 or 10% Point Williams
Wind Direction (degrees) 0 to 360 1 ± 3° Point Williams, Dockton
Vaisala Wind Speed (m/sec) 0 to 60 0.1 ± 0.3 or ± 3% Point Williams, Dockton
RM Young HD Wind Speed (m/sec) 0 to 100 0.1 ± 0.3 or ± 1% Point Williams, Dockton
Air Temperature (°F) -60 to 140 0.1 ± 0.3 Point Williams, Dockton
Pressure (in Hg) 17.7 to 32.5 0.01 ± 0.015 Point Williams, Dockton
Relative Humidity (%) 0 to 100 0.1 ± 5% Point Williams, Dockton
Rain Fall (in) NA 0.001 ± 5% Point Williams, Dockton
Photosynthetically Active Radiation (µmol/s/sq meter) NA 1 ± 5% Point Williams, Dockton

Obsolete Sensors

Sensor Range Resolution Accuracy
YSI Depth (m) 0 to 61 0.001 ± 0.12
YSI Temperature (°C) -5 to 50 0.01 ± 0.15
YSI Conductivity (mS/cm) 0 to 100 0.001 to 0.1 ± 0.5% of reading
YSI Salinity (psu) 0 to 42 0.01 0.1 psu or 1%, whichever is greater
YSI Dissolved Oxygen (mg/L) 0 to 50 0.01 ± 0.1 mg/L or 1%, whichever is greater
YSI Turbidity (NTU) 0 to 1,000 0.1 0.3 NTU or 2%, whichever is greater
YSI Chlorophyll (µg/L) 0 to 400 0.1 ~0.1 µg/L detection limit
Sonde pH (YSI) 0 to 14 0.01 ± 0.2

Download Data

Use our online data visualization tools or download data.

Note: some data may be provisional. Contact MarineWQ@kingcounty.gov for information about the most recent quality control of data. 

Documentation

Learn more about our program by reading relevant reports and presentations.

Contact us with any questions or access additional resources in the Science Section Library.

expand_less