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

Stormwater, drainage, and land disturbing regulations are updated from time to time. Projects are vested to a particular version of the regulations depending upon when they are submitted. Projects may be vested to one of three different codes:

Note: Significant Change in Vesting of Stormwater Regulations Will Impact Developers and Others in Snohomish County

A recent Washington State Supreme Court decision related to stormwater will have significant impact on development in Snohomish County. The greatest impact will be on property developers. The Snohomish County Department of Planning and Development Services (PDS) is assessing the Supreme Court’s decision and determining ways to work with permit applicants to address the new requirements


On December 29, 2016, the Washington State Supreme Court (Court) issued a decision in Snohomish County et al v. Pollution Control Hearings Board related to the County’s compliance with its Phase I Permit. The Court held the County’s updated stormwater regulations are not “land use control ordinances” subject to state vesting statutes. This is a significant change in the law for developments across the state. Read the Court's decision here.

Snohomish County is a Phase I jurisdiction under the federal Clean Water Act National Pollutant Discharge and Elimination System (NPDES) program. The County must comply with its Phase I Municipal Stormwater NPDES Permit. One aspect of the County’s compliance with its Phase I Permit is the adoption of updated stormwater drainage regulations, which the County accomplished effective January 22, 2016. The following regulations constitute the County’s updated stormwater regulations:

For more information on the permitting process for the County's stormwater regulations, please visit the Stormwater and Drainage Regulations webpage.


Contact Us

Phone: 425-388-3311
Fax: 425-388-3872

PDS's Response to the Court's Decision

At this time, PDS is assessing the impacts of the Court's decision and determining ways to work with permit applicants to implement the decision. PDS recognizes this recent Supreme Court decision may have a significant impact on some development projects, and is evaluating ways to facilitate the permitting process to minimize that impact.

As PDS weighs the impacts of the Court's decision, it may consider process changes or code changes as a means to respond to the decision.

In the meantime, if you have specific questions about your project please use the contact information provided below:

  • 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 at this on our Postcard page.
  • If you are preparing to submit an application for a permit, you can request an appointment at this Permits and Forms page or 425-388-3311. 
  • For general information about the County's stormwater regulations and impacts on developments, please email Ken Crossman, and 425-262-2227. 

 PDS will update this page as more information becomes available.