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What is a Critical Areas Designation?

A Critical Areas Designation is a process that allows a property owner to define the limits of critical areas on or near the project site, establish buffers and other required mitigation measures and, when coupled with the Consolidated Review option, address all related site issues such as access and drainage control.  Critical Area Designation Handout

What are the advantages of a Critical Areas Designation?

A Critical Area Designation

  • offers customers consistency and predictability in decision-making as applied to critical areas and associated buffers.

  • puts critical area review at the beginning of the permit review process. This means that customers will know where they can and cannot build on their property. In the case of wells, septic tanks and drain fields, customers will know prior to hiring an engineer or critical areas consultant where these systems can be located.

  • can save time and money associated with plan changes or redesigns that might occur in the middle of the permit review process, if critical area issues have not been addressed prior to Seattle - King County Public Health Department review.

  • allows customers who wish to sell property an opportunity to identify critical areas and their buffers on site. The designation helps identify buildable areas and offers the associated predictability and reliability for five years after the determination.

  • allows for critical areas issues beyond location and classification to be addressed. For example, wetland buffer widths or a mitigation plan for driveway crossing impacts could be included within the designation.

When is a Critical Areas Designation required?

A Critical Areas Designation is required before submitting an application to Seattle-King County Public Health for septic system or well approval for residential projects.

As of January 1, 2007, customers are required to complete the Critical Areas Designation (CAD) process prior to filing an application for a new subdivision. Prior to January 2007, customers initiating the permit process for a new subdivision were encouraged to use the CAD program voluntarily.

How much will a Critical Areas Designation cost?

Please refer to the Department of Local Services, Permitting Division (Permitting) current fee schedule for more information.

Under some circumstances, performance and maintenance financial guarantees may be required for restoration and mitigation activities. See the Permitting Customer Information Bulletin #40, Financial Guarantees, or call 206-296-6600 for more information.

Where can I get the application for a Critical Areas Designation?

The Critical Areas Designation application is available online through If you have questions or would like to inquire about alternatives, please email

What is the timeline for processing a Critical Areas Designation?

Permitting will determine a Critical Areas Designation within 120 days after the application for a Critical Areas Designation is complete.

How long is a Critical Areas Designation valid?

A Critical Areas Designation is valid for five years from the date of the completed CAD letter.

What is the appeal process for a Critical Areas Designation?

Except as provided in King County Code 21A.24.500(E), the determination by Permitting is final.

Legal authority

Title 21A.24 of the King County Code.


Critical areas specialists are available to assist walk-in customers at the Permitting Department Customer Service Center in Snoqualmie - see customer services for more information. You may also direct questions to us at 206-296-6600.

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