Grading, Drainage, and Clearing Requirements (Land Disturbing Activity)

Why is regulation of stormwater runoff important?

Stormwater runoff is rain that runs off hard surfaces, rooftops, streets, parking lots, and landscaped areas. As water runs off these surfaces, it can pick up pollutants such as oils, dirt, and fertilizers. Polluted stormwater runoff is a leading contributor to water pollution in the Puget Sound region.

Runoff can also cause and contribute to flooding. When runoff is uncontrolled, it could result in the destruction of property, harm to fish and wildlife, damage to aquatic habitats, loss in aesthetic values, and cause threats to public health due to contaminated food, drinking water supplies, and recreational waterways.

Snohomish County is committed to complying with federal and state requirements to provide effective and efficient stormwater management in our community. As part of our work, we maintain stormwater regulations that guide new development and redevelopment to minimize pollution and harmful effects of stormwater.


Where can I find the County’s Stormwater regulations?

Please visit the Stormwater and Drainage Regulations webpage for more information on the permitting process and links to associated checklists and assistance bulletins.

The County’s current stormwater and drainage requirements are found in:

Contact Us

  • If you have questions about a specific application already submitted to PDS, please contact your project manager/contact. To locate your project manager/contact, enter your project file number on our Postcard page.
  • If you are preparing to submit an application for a permit, see information on the Permits, Applications, and Forms page or visit
  • For general information about the County’s stormwater regulations and impacts on development, please email Ken Crossman or call 425-262-2227.