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:
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
Many construction sites will need to apply for coverage under the CSWGP. Construction site operators are required to be covered if both of these apply:
*Count the cumulative acreage of the whole project, whether it's single or multiphase. Include off-site disturbance acreage from support activities related to the construction site. This applies if your project is a portion (less than one acre) of a larger project planned over time.
You will need to set up an account to use our WQWebPortal to apply for coverage:
You will need to set up an account to use our WQWebPortal to submit a DMR:
Check out our eCoverage packet for more information about your requirements.
See contaminated water on construction sites for guidance.
Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, and Yakima
Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County
Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Mason, Lewis, Pacific,
Skamania, and Wahkiakum
Pierce and Thurston Counties
King (except for the cities of Seattle and Kent) Skagit, Snohomish, and Whatcom
Island or San Juan counties
City of Kent, City of Seattle, Kitsap, Pierce, or Thurston County
Construction Stormwater General Permit Writer