Stormwater runoff from construction sites can carry muddy water, debris, and chemicals into local waterways. Sediments, chemicals, and debris can harm aquatic life and reduce water quality.
We require regulated construction sites to get coverage under the Construction Stormwater General Permit (CSWGP). Following the requirements in this permit helps control and reduce water pollution. If water on your construction site is contaminated see this guidance for contaminated water on construction sites.
Operators of regulated construction sites are required to:
- Develop stormwater pollution prevention plans.
- Implement sediment, erosion, and pollution prevention control measures.
- Obtain coverage under this permit.
The current modified permit went into effect May 5, 2017, and expires Dec. 31, 2020.
To receive updates about this permit, sign up for our listserv
I've got permit coverage. Now what?
Check out our eCoverage packet for more information about your requirements.
What do I do with contaminated water?
See contaminated water on construction sites for guidance.
Not finding what you're looking for?
See our regional contacts
page to help find a person to answer to your questions.
For Permittees in the following cities and counties:
City of Seattle, Skagit, or Whatcom county
Thurston, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Skamania, or Wahkiakum County
Clallam, Kitsap or King County (with the exception of the City of Seattle)
San Juan, Island, Pierce, Kittitas, Yakima, Benton, or Klickitat County
Adams, Asotin, Chelan, Columbia, Douglas, Ferry, Franklin, Garfield, Grant, Lincoln, Okanogan, Pend Oreille, Snohomish, Spokane, Stevens, Walla Walla, Whatcom, Whitman, or Yakima County
Construction Stormwater General Permit Questions