Municipal Stormwater General Permit - NPDES

What is the purpose of this permit?
This permit is required for municipalities and other public entities that collect stormwater runoff in municipal separate storm sewer systems (MS4s) that discharge to surface waters. The permit requires development and implementation of a stormwater management program to reduce the contamination of stormwater runoff and prohibit illicit discharges.
Who issues this permit?
Department of Ecology
What activities require this permit?
Generally this permit is required of all municipalities within U.S. Census Bureau-defined urban areas and for designated cities with a population over 10,000 located outside of urban areas. Urbanized areas are population centers with greater than 50,000 people and densities of at least 1,000 people per square mile, with surrounding areas having densities of at least 500 people per square mile. The urbanized areas in this permit are based on the 2000 population census. The Washington State Department of Transportation is also required to have coverage within permitted municipalities.

Other public entities (such as ports, prison complexes, parks and drainage districts, and universities) that own or operate a storm sewer system and are located within a permitted municipality may require coverage. Ecology uses the term Secondary Permittees to refer to these entities. The MS4s of Secondary Permittees are publicly owned or operated and serve more than 1,000 people on an average day. For ports, schools, colleges and universities the population figures include commuters as well as residents.
How much will this permit cost?
Permit fees are set by rule and are found in Washington Administrative Code (WAC) Chapter 173-224. Fee amounts can change, so please consult the WAC or contact your Ecology Regional Office for current fees.
Where can I get the application for this permit?
The application is called 'Notice of Intent (NOI) for Coverage under a National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater General Permit' is online and can be accessed at
Do I need to include anything with my application?
Potential permittees should contact their regional office contact to discuss additional information that may be required to process the application.
Is the decision on my permit dependent on anything besides the information in my application?
When making the decision on your permit, Ecology will consider the applicable laws and rules, the contents of your application, and the background environmental conditions.

In addition, updates to U.S. Census Bureau-defined urban areas and/or existing permittee boundaries may affect Ecology's decision on the need for permit coverage.

Lastly, the application for coverage has a public review requirement. This means that the public may submit comments to Ecology during the 30 day public comment period to support or oppose your proposed activity. If any comments are received, Ecology must review and respond to the comments and take them into consideration when making the decision to issue or deny permit coverage.
How long will it take to review my application?
Ecology will work with applicants to develop a permit issuance schedule that recognizes the applicant's needs. A public notice must be published at least once each week for two consecutive weeks in a single newspaper of general circulation in the county or city in which the district or entity is located. See the NOI instructions for the public notice language requirements. Permit coverage will not be granted sooner than 31 days after the date of the second public notice.
Where do I submit my application?
The application is submitted to the address listed in the NOI:
    Department of Ecology Water Quality Program Municipal Stormwater Permits P.O. Box 47696 Olympia, WA 98504-7696
How long is my permit valid?
Your General Permit is valid for up to 5 years. Coverage for a facility begins at time of application approval and ends when the General Permit expires or your coverage is revoked. The current term of the Western Washington Municipal Stormwater General Permits will expire on July 31, 2018; the Eastern Washington Municipal Stormwater Permit will expire on July 31, 2019. However, Ecology may administratively extend the General Permit past 5 years until the agency has completed the permit renewal process.
What is the appeal process for the permit?
You have a right to appeal this permit coverage to the Pollution Control Hearings Board (PCHB) within 30 days of the date of permit issuance. The appeal process is governed by Chapter 43.21B RCW and Chapter 371-08 WAC. "Date of receipt" is defined in RCW 43.21B.001(2). To appeal you must do the following within 30 days of the date of receipt of permit issuance notice:
  • File your appeal and a copy of this notice with the PCHB (see addresses below). Filing means actual receipt by the PCHB during regular business hours.
  • Serve a copy of your appeal and this notice on Ecology in paper form - by mail or in person. (See addresses below.) E-mail is not accepted.
            Physical Addresses:             Department of Ecology             Attn: Appeals Processing Desk             300 Desmond Drive SE             Lacey, WA 98503             Pollution Control Hearings Board             1111 Israel Road SW, Suite 301             Tumwater, WA 98501             Mailing Addresses:             Department of Ecology             Attn: Appeals Processing Desk             P.O. Box 47608             Olympia, WA 98504-7608             Pollution Control Hearings Board             P.O. Box 40903             Olympia, WA 98504-0903
Notes / Comments:
Contact the appropriate regional office or the statewide contact listed below if you have any questions about municipal stormwater permit coverage.
Legal Authority:
Department of Ecology
Water Quality Program
300 Desmond Drive
PO Box 47600
Olympia, WA 98504-7600
Fax: (360) 407-6426
Telephone: (360) 407-6600
Triggering Questions:
  • Does your municipality have a separate storm sewer system that discharges to surface waters?
* Permit information last updated 8/21/2023