Industrial Stormwater General Permit

Stormwater can pick up pollution from factories and businesses. Those contaminants are carried into waterways and harm fish and other aquatic life. The Industrial Stormwater General Permit (ISGP) helps industrial facilities comply with federal regulations that reduce pollution. We require most industrial sites in Washington to monitor, measure, and reduce stormwater pollution leaving their site.

Find the types of facilities that require coverage under the ISGP in Table 1 of the current permit.

The current permit went into effect Jan. 2, 2015, and expires Dec. 31, 2019.

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Current permit and related documents

Permit reissuance - 2019

The current permit expires on Dec. 31, 2019. We plan to reissue an updated general permit in Nov. 2019.

What's changing:

We are updating the current permit language to make the following changes:

  • Adding two new industry groups that require coverage:
    • Marine construction
    • Construction, transportation, and mining equipment rental and leasing
  • Changing the timing of first flush
  • Revising requirements for consistent attainment

We will provide draft permit documents for review and instructions on how to comment on May 1, 2019.


Spring 2019: Formal public comment period on the draft permit
Nov. 2019: Issue final permit
Early 2020: Permit effective

Public outreach and listening sessions

We held listening sessions throughout the state in fall of 2018. The statewide webinar was recorded and is available below. The webinar goes through the proposed changes to the permit.

Download and view the webinar (35 MB)

If you have specific questions about the permit reissuance, please contact Travis Porter.

Previous permit documents

Permit applications and forms


Contacts for assistance

Central Region

For permittees located in the following counties:

Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, and Yakima

Clay Keown
Permit Administrator

Eastern Region Northwest Region Southwest Region