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King County

Location of King County in Washington StateKing County is located on Puget Sound in Washington State.  It is bordered on the north by Snohomish County, the northeast by Chelan County, the southeast by Kittitas County, the south by Pierce County and across the Puget Sound on the west by Kitsap County.  As of the 2010 U.S. Census, King County has a total land area of 2,115.57 square miles and a population of 1,931,249.  Seattle is its largest city with a population of 608,660. Also of interest:

  • The intersecting watershed sub-basins(9):  Puyallup, Naches, Upper Yakima, Wenatchee, Puget Sound, Lake Washington, Duwamish, Skykomish and Snoqualmie.
  • Major lakes:  Lake Washington, Lake Sammamish and Chester Morse Lake.
  • Major rivers:  Green River, White River, Snoqualmie River, Cedar River, Taylor River, Tolt River, Sammamish River and Skykomish River.
  • Mount Daniel (7,960 feet) is part of the Cascade Range and the highest point in King County.

U.S. Census Bureau QuickFacts for King County, WA

King County Biodiversity Report

Office of Financial Management (OFM) county data for King County, WA

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Related articles

Pat Collier walking along the restored beach in front of her Maury Island home. Photo: Christopher Dunagan/PSI

By removing bulkheads where they can, property owners are improving shoreline habitat, one piece at a time. Officials from county and nonprofit groups have been offering assistance and finding new ways to connect with property owners.

Nearshore habitat , King County
Returning sockeye salmon packed gill-to-gill in the viewing windows at the Ballard Locks fish ladder. Photo: Ingrid Taylar (CC BY-NC 2.0) https://www.flickr.com/photos/taylar/7511895940

Chinook, coho and sockeye salmon, along with steelhead trout, live in the Lake Washington watershed and navigate a treacherous route through the Ballard Locks on their way to Puget Sound.

Water quantity , Species and food webs , Fishes , Freshwater habitat , King County
Appendix 5. Map of Skykomish/Tye River Control Locations 2014

The final report on a knotweed removal and native plant project from grant PO-00J08401 to King County DNR for the grant entitled: Protection and enhancement of the riparian buffers in WRIA 7 through restoration and stewardship.

Water quality , Plants , Terrestrial habitat , Freshwater habitat , Skykomish Watershed, Snoqualmie Watershed, King County
Report cover photo by Victor Mesny.

A 2014 report by the North Cascadia Adaptation Partnership identifies climate change issues relevant to resource management in the North Cascades, and recommends solutions that will facilitate the transition of the diverse ecosystems of this region into a warmer climate.

Water quality , Species and food webs , Plants, Mammals, Birds, Fishes , Freshwater habitat , Terrestrial habitat , Clallam County, King County, Skagit County, Snohomish County, Whatcom County, Puget Sound Watershed, Snohomish Watershed, Stillaguamish Watershed, Upper Skagit Watershed

A 2014 King County report projects the capital and maintenance costs of the stormwater treatment facilities that would be needed, within WRIA 9 and the Puget Sound region, to fully comply with the Clean Water Act. 

Water quantity , Water quality , Healthy human population , Marine habitat , Estuarine habitat , Nearshore habitat , Freshwater habitat , King County
Seattle's central waterfront at sunset. Photo: Michael Matti (CC BY-NC 2.0) https://www.flickr.com/photos/michaelmattiphotography/9090323308/

The decaying seawall along Seattle’s waterfront is providing scientists with an opportunity to improve long-lost habitat for migrating salmon. It could also show the way for habitat enhancements to crumbling infrastructure worldwide. One University of Washington researcher describes the project.

Species and food webs , Fishes , Marine habitat , Nearshore habitat , Shoreline Habitats , King County, Puget Sound Watershed, Puget Sound Main Basin
Ribbon seal sighted on January 11th, 2012 a dock on the Duwamish River, Seattle, Washington (credit Matt Cleland)

Can Puget Sound claim a new species? Ribbon seals were not previously thought to venture into the Salish Sea, but a series of sightings in Puget Sound in 2012 expands their potential range. Scientists are keeping an eye out for future sightings. 

Species and food webs , Mammals , King County, Snohomish County, Duwamish Watershed
Beach near the Olympic Scuplture Park before restoration. Photo by Jason Toft

This paper describes a multi-year effort testing whether shoreline enhancements at the Olympic Sculpture Park in Seattle have improved conditions for fish and invertebrates as compared to armored shorelines.

Marine habitat , Nearshore habitat , Shoreline Habitats , King County
Moss Lake, part of a bog wetland complex in Moss Lake Natural Area. Photo by Jennifer Vanderhoof.

Wetlands are recognized as critical ecosystems for biodiversity because of their disproportional use by wildlife and exceptional habitats for plants. It is their unique combination of shallow aquatic habitats and adjacent terrestrial conditions extending over a wide range of geomorphic and elevational settings that accounts for their ecological complexity and resultant richness. Because of their landscape setting, each wetland tends to exhibit unique habitat types and characteristic arrays of species adapted to idiosyncratic conditions, products of each wetland’s ecological and evolutionary history.

Estuarine habitat , Freshwater habitat , King County
Mountain goats are commonly found in alpine habitat. Photo by Jennifer Vanderhoof.

Except for a very small area in the SE corner of the County, the subalpine and alpine habitats are located in the North Cascades Ecoregion that occupies the NE quarter of King County. This ecoregion is composed of steeply dissected valleys that rise precipitously to the subalpine (montane) forests, meadows, and parklands and, in a short distance more, to the alpine ridges and peaks of the Cascade Crest. The habitats that typify this high-elevation zone are among the most undisturbed habitats remaining in King County.

Terrestrial habitat , King County
The Snoqualmie River. Photo copyright King County.

The diversity of streams in the county is a reflection of the diversity of its geography. From the small rivulets that begin high in the Cascade Mountains, to the brooks that flow gently across the lowlands, to the five major rivers of the county, there are over 4,800 kilometers (3,000 miles) of perennial streamcourses in King County.

Freshwater habitat , King County, Duwamish Watershed, Lake Washington Watershed, Puyallup Watershed, Skokomish Watershed, Snoqualmie Watershed
A section of Griffin Creek. Photo copyright King County.

Riparian habitats are often characterized by particular trees and shrub species that line the banks of most rivers and streams in the lowlands and foothills of King County.

Freshwater habitat , King County
Seagrass meadows provide valuable habitat. Photo by Randy Shuman.

King County contains four major marine habitats: backshore, intertidal and shallow subtidal, deep subtidal, and riverine/sub-estuarine. Descriptions of each of these habitats and the types of flora and fauna associated with them are provided below.

Marine habitat , Estuarine habitat , Nearshore habitat , King County
Red alder, a deciduous species that often grows in disturbed areas. Photo copyright King County.

The history of land use in King County has produced a lowland and foothill landscape of bewildering variety. The once continuous forest of western hemlock, Douglas-fir, and redcedar has given way to a patchwork of lawns, parks, playgrounds, woodlots, greenbelts, old fields, croplands, tree farms, and remnant forests set amid a landscape of urban, suburban, rural, and commercial uses, all joined and, at the same time, separated by a vast network of roads and communication corridors. Despite this apparent richness and variety of patches, this landscape is clearly human-dominated, and habitats for native species have generally been marginalized by the scale and pace of land conversion and resource extraction. This pattern is not, of course, unusual in the history of development.

Terrestrial habitat , King County
Canada geese, commonly seen in Lake Washington. Photo by Jennifer Vanderhoof.

The natural biodiversity of the lakes of King County is strongly influenced by geography. The county runs from the Cascade mountain crest to the shores of Puget Sound, covering all three different Level III ecoregions (Puget Lowland, North Cascade, and Cascade). The geology, elevation, climate, and ecology in these three ecoregions are all different, and these differences in environmental factors determine the natural biodiversity of the lakes and also influence the risks, vulnerability, and impacts to that biodiversity.

Freshwater habitat , King County
Aerial view of the Vashon Island shoreline.

Ecoregions provide a useful framework and background for the discussion of marine, freshwater, and terrestrial environs of the county. The discussion of ecoregions is based on U.S. Environmental Protection Agency (EPA) ecoregion conventions, which result in units similar to European biogeographical regions because they denote areas of general similarity in ecosystems.

King County
King County map, showing incorporated land and major water bodies. Copyright King County.

Ecoregions provide a useful framework and background for the discussion of marine, freshwater, and terrestrial environs of the county. The discussion of ecoregions is based on U.S. Environmental Protection Agency (EPA) ecoregion conventions, which result in units similar to European biogeographical regions because they denote areas of general similarity in ecosystems.

King County
King County map, showing incorporated land and major water bodies. Copyright King County.

Ecoregions provide a useful framework and background for the discussion of marine, freshwater, and terrestrial environs of the county. The discussion of ecoregions is based on U.S. Environmental Protection Agency (EPA) ecoregion conventions, which result in units similar to European biogeographical regions because they denote areas of general similarity in ecosystems.

King County

Learn more about demographics in King County, Washington.  The U.S. Census Bureau published the following quick facts.

Counties, King County