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King County wetlands

Learn about wetlands in King County such as their value to clean water and healthy habitat, reducing floods and supporting biodiversity and find wetland maps, regulations and studies.

Riverine wetland along Green River

Wetland permits, guidelines and regulations

Introduction to wetlands

Wetlands are overflowing with life. In all, some 212 species of wildlife and many species of plant life depend on western Washington's wetlands for survival.

Permits–customer services

Submit your questions online, email or call to pursue permits.

Wetlands - identification of and delineation of boundaries - categories

King County code describing King County's wetland regulations. As of 2024, reference sections include 21A.24.318 through 21A.24.345.

Code violations

Notify the Department of Local Services code enforcement of wetlands getting filled, drained or cleared, 24 hours a day, 7 days a week.

Mitigation Reserves Program

Unavoidable damage to wetlands can be mitigated through this permit program, which enables applicants to pay King County to complete wetland related projects in other places.

Wetland maps and data

iMap interactive map

Open the layer list and select "Environmentally Sensitive Areas" to view wetlands and sensitive area notices on property titles, which include King County wetlands.

1990 King County Wetlands Inventory Notebooks

King County's original wetland survey includes known wetlands in 1990 unincorporated area with aerial photos showing estimated wetland edge, measurements and animal and plant survey data. Scanned notebooks are provided in Adobe Acrobat format:

Wetland science

Beavers in King County

Find the latest on beavers in King County including biology and life history, environmental benefits beavers provide, challenges and solutions, and resources for beaver management such as scientific papers and illustrations.

Characteristics of the low-elevation Sphagnum-dominated peatlands of western Washington: a community profile

Also known as "the bog book", this publication provides a compilation of data and findings about local sphagnum-dominated peatlands.

Wetland documents

Results of search for King County's wetland-related science documents published 1997 to present.

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