Critical Areas – Floodplain
Call King County’s River and Floodplain Management Section (Department of Natural Resources and Parks) at 206-477-4727. They can tell you how to get this information.
The actual presence or absence of critical areas on the ground, as defined in Title 21A of the King County Code, determines permit requirements for property in unincorporated King County, regardless of what is shown on maps or listed in other documents.
King County has not mapped all critical areas on all property within its boundaries. See the Property Research and Maps web page for information and tools for researching your property.
Options for finding out if critical areas are present
- Briefly discuss a proposed project with Permitting Center staff on the phone (206-296-6600) or in person at our offices.
- Apply for a Critical Areas Designation to have a parcel investigated for critical areas. There is a charge for this service, but a Critical Areas Designation can prevent unexpected expenses during the permit review process by providing information about potential site constraints affecting a proposed project before detailed construction plans are drawn up.
- A Critical Areas Designation is required for any site in the rural area where a new well or on-site septic system is proposed.
Permitting staff will ask several questions, such as the following:
- Is there a stream, lake, wetland, or steep slope on or next to the property? (Buffers may extend across property lines.)
- Are there areas on the property where coal mining was done in the past, or areas with easily eroded soils?
- Are you aware of any wildlife—such as red-tailed hawks or eagle nests—near the property?
See our Property Research Guide for wide range of information on available property information resources. Please note that web-based information is a guide only; it does not accurately show all critical areas on a parcel, or the precise boundaries of those areas that are shown.
Please also refer to our Critical Areas Designation Handout.