skip to main content

Department of Permitting and Environmental Review

Department of Permitting and Environmental Review
35030 SE Douglas St., Ste. 210
Snoqualmie, WA 98065-9266

Phone: 206-296-6600
TTY Relay: 711

Service Center Hours

Critical Areas, Stormwater, and Clearing and Grading Ordinances (CAO)

*New CAO Effectiveness Study 

Results, conclusions and background information from a comprehensive five-year (2007-2012) US EPA-grant funded study of land use and regulations in rural King County.

Adopted ordinances

King County's updated Critical Areas Ordinance ("CAO") went into effect on January 1, 2005.  March 2009 update:  See questions and answers regarding Court rulings on King County's clearing limits in the CAO for recent developments.

The CAO has been incorporated into the King County Code. The King County Code is available online at The CAO has been codified as follows:

How does the CAO affect me?

King County has developed informational materials at different levels of detail to assist property owners, builders, consultants, and the general public in understanding the provisions of the CAO:

  • Fact Sheets briefly describe the different elements of the CAO and its provisions to different types of critical areas and in different situations.
  • Answers to Frequently Asked Questions.
  • PowerPoint slide show presented at a Permitting Department CAO Workshop provides a general overview of the entire CAO.
  • The CAO User's Manual provides detailed information on the CAO in a more easily understandable format to assist property owners and permit applicants in understanding how the CAO will be applied.
  • Best Available Science provides background information that was used by King County in developing the CAO.

Fact sheets

Questions & answers

CAO educational presentations

the Permitting Department has presented free workshops on the Critical Areas Ordinance. For those unable to attend, the workshop is available for viewing online, on KCTV, or by DVD. See DDES Workshops and Events for more information.

A PowerPoint presentation from the CAO workshop also is available in the following formats:

CAO user's manual

Part One - Administration
Part Two - Critical Areas
Part Three - Surface Water
Part Four - Clearing and Grading

CAO User's Manual as one document (entire file, PDF*, 2.1MB)

Best available science

Volume I: Review of Science Literature
Volume II: Assessment of Proposed Ordinances
Literature References

*Note: To view PDFs, free software from Adobe is required. PowerPoint documents require Microsoft software.  See helpful hints for assistance.

To request this information in alternate formats for people with disabilities, call 206-296-6600 or TTY Relay:  711.