Critical areas / floodplains
Call the DNRP River and Floodplain Management Section at 206-477-4727 and they can provide you with instructions on how to obtain the information you are looking for.
The actual presence or absence of critical areas on the ground, as defined in Title 21A of the King County Code (KCC), determines permit requirements for property in unincorporated King County, regardless of what is contained in maps and other documents.
King County has not mapped all critical areas on all property within King County. Customers may contact the Permitting Department Customer Information at 206-296-6600 to discuss the process of finding out whether a property contains critical areas. Please have the Tax Parcel Number available.
Options for determining the presence of critical areas include:
- Briefly discuss a proposed project with Permitting Center staff on the phone (206-296-6600) or in-person at our offices.
- Set up a Critical Areas Inquiry or Designation to have a parcel investigated for critical areas. While the Permitting Department does charge by the hour for this service, a Critical Areas Inquiry or Designation can save the property owner unanticipated expense during the permit review process by providing information about potential site constraints affecting a proposed project in advance of preparing detailed construction plans. A Critical Areas Designation is now required for any site in the rural area proposing to install a new well or on-site septic system.
- Complete a formal building or development permit application, which may be followed by a Critical Areas Review.
The Permitting Department staff will ask several questions, such as:
- Is there a stream, lake, wetland or steep slope on or adjacent to the specified property? (Buffers may extend across property lines.)
- Are there areas on the specified property where coal mining activities were previously conducted, or areas with easily eroded soils?
- Are you aware of any wildlife such as red-tailed hawks or eagle nests in the vicinity?
Property research is available through the Permitting Department Web site at www.kingcounty.gov/property/permits/gis.aspx, where customers also may access a variety of parcel-specific information. For maps and descriptions of individual parcels, go to www.kingcounty.gov/operations/GIS/PropResearch.aspx. Please note that Web-based information is a guide only; it does not accurately show all critical areas on a parcel. For those critical areas that are shown, precise boundaries are not indicated.
Please also refer to the Permitting Department Customer information Bulletin #21, Critical Areas Review (PDF*, 142KB).