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.

The current permit went into effect Jan. 2, 2015, and expires Dec. 31, 2019. The new permit is effective on Jan. 1, 2020, and expires on Dec. 31, 2024.

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Current permit and related documents

Permit Reissuance

We accepted public comments on the draft permit documents from May 1, 2019, to June 29, 2019. We held six public workshops and hearings across the state, including an online webinar. During the workshops, we explained the proposed changes to the permit and answered questions. The public hearings provided the opportunity for the public to give formal comments on the draft permit. See our Response to Comments document that address comments submitted during the public comment period. 

Previous permit documents

Permit applications and forms