Critical areas are lands with natural hazards or lands that support certain unique, fragile or valuable resource areas.
Lands designated by King County as critical include areas at high risk for erosion, landslides, earthquakes or flooding; coal mines; or wetlands or lands adjoining streams, rivers and other water bodies.
The King County Code protects critical areas as well as their buffers in order to protect public health and safety, and to promote environmental health in the region. Buffers are areas adjacent to a critical area that are also restricted from specific building and development activities.
When a development proposal occurs near wetlands, lakes, wildlife habitat or streams, an applicant may be asked to provide additional information with the permit application in order to enable the Department of Local Services, Permitting Division (Permitting) staff to better assess potential impacts the development might have on these critical areas.
A reasonable use exception is used only when all reasonable uses of a site, as allowed by adopted zoning, is denied as result of critical areas.
Critical area reports
When a development proposal occurs near wetlands, lakes, wildlife habitat or streams, an applicant may be asked to provide additional information with the permit application in order to enable Permitting Department staff to better assess potential impacts the development might have on these critical areas. Reports commonly requested are a Wetland Delineation Report and/or a Stream Survey Report.
In addition, some development proposals may encroach into the stream or wetland or buffer. If this occurs, a Critical Area Mitigation Plan will be required. For small projects, typically on single-family residential lots involving less than 1,000 square feet of buffer enhancement, a Basic Restoration and Enhancement Plan may be required. These mitigation and enhancement plans are also used when there has been unpermitted activity, such as clearing and grading, in a critical area or buffer to help get the property owner back into compliance with code and the critical area better protected.
The following report guidelines are available to assist in preparing these reports:
- Critical Areas, Wetland Delineation Report Criteria (191KB) The purpose of a wetland delineation report is to convey an objective, factual picture of the extent and location of wetlands at a given site.
- Critical Areas Restoration and Enhancement (614KB) This document is intended to assist property owners in the restoration or enhancement of critical areas and their buffers. They include instructions on how to determine the number and types of plants to use, how to prepare a basic planting plan, and how to monitor and maintain the project.
- Stream Survey Report Criteria -- This document is not currently available in electronic format. It can be obtained by contacting Customer Service at 206-296-6600 or by email at dperwebInquiries@kingcounty.gov. These guidelines address the appropriate scope and methods of stream and fisheries studies, and recommend 3 progressive levels of detail based on stream system classification and fish utilization.