Science services
Explore the science of King County
Toxic chemical assessment
Learn how King County scientists track toxic chemicals, assess risks to humans and wildlife, and guide efforts to support healthier communities and ecosystems.
Lake swim beach monitoring
During the summer, we test the water for bacteria at many lake beaches in King County. Explore this page to learn about where, how, and why we monitor and to find a health beach near you!
Lake services and monitoring
King County provides an array of services and information to facilitate lake management, monitoring, and enjoyment.
Water quality monitoring data
Use this map to find water quality data from across King County, including biological, chemical, and hydrologic data.
Benthic macroinvertebrate (stream bug) monitoring
Learn why aquatic insect counts provide insight about the health of streams, and look up measures for many streams in King County, Washington.
Stream monitoring
Learn about our stream monitoring program and look up water quality data and graphs for streams and rivers including temperature, dissolved oxygen, pH, turbidity, conductivity, total suspended solids, phosphorus, nitrogen, bacteria, metals, precipitation, overall water quality index, and toxicity and pesticide studies
Puget Sound marine monitoring
Get water quality, plankton, fish and crab tissue, and sediment data sampled from the marine waters in Puget Sound.
Groundwater management and data
Learn how King County manages aquifers for drinking water and look up water quality sample data and well levels using a map.
Hydrologic Information Center
Look up records for over 500 sites for stream gages on rivers and streams, rain gages, gages in wetlands, lakes and detention facilities, groundwater wells, and water quality samples.
Wildlife
Learn about biodiversity, stream bugs, fish and shellfish, beavers, and creatures that live in Puget Sound.
Science document search
Find local scientific documents going back decades on topics such as natural features, water quality, wastewater, ecology and biodiversity, modeling and analysis.
Technical Document and Research Center
King County's science library curating local scientific publications going back to the 1800's.
Projects - environment, ecology and conservation
Environmental projects that restore fish and wildlife habitat, improve water quality, reduce flood risk and manage stormwater.
PFAS/forever chemicals
Actions to protect the people, fish, and wildlife from human-made toxic chemicals.
Headwaters: Stories from the Science Section
Visit our blog to get science straight from the source. You'll find stories about King County's environmental research and the people behind the work.
News and announcements
December 8, 2025
VIDEO: 'A healthy lake sends a powerful message’: Landmark King County study of Lake Washington finds that cities can grow without harming water quality
A study by King County scientists – recently published in a national scientific journal – found surprising improvements in Lake Washington’s water quality this century, even as the watershed’s population increased by 350,000 people.
April 21, 2025
VIDEO: One year later, King County’s largest-ever floodplain restoration project is improving salmon health
One year after completing the largest floodplain restoration project in King County's history, ecologists report young Chinook salmon are growing considerably well in the newly restored habitats along the Snoqualmie River, validating the county’s approach to improving habitat and offering a blueprint for future salmon recovery work.
March 27, 2025
VIDEO: King County scientists identify a potential breakthrough for treating salmon-killing tire chemical
Research by King County's Water and Land Resources Division confirmed the effectiveness of soil mixture that treats 6PPDQ, a toxic chemical found in tire dust that causes coho salmon to die before they return to their spawning grounds.
Translate