Water Treatment Plant General Permit

Water treatment facilities produce water for drinking and for industrial businesses. The Washington State Department of Health makes sure that drinking water is safe and reliable for people. Our role is to ensure any byproducts from water treatment that are released from these facilities do not harm the environment.

Treatment can involve:

  • Filtering and settling out sediment and disease-causing organisms.
  • Using chemicals to kill organisms or remove excess minerals and other contaminants.
  • Adjusting disinfection and chemicals to reduce scaling or corrosion within the delivery system.

We have developed the Water Treatment Plant General Permit to help treatment facilities comply with state laws and the Federal Water Pollution Control Act. This permit contains specific requirements and conditions for permittees to protect rivers and other waterbodies that receive wastewater discharges.

For a short explanation of the permit, please read the Water Treatment Plant General Permit Focus Sheet

The current permit went into effect on Sept. 1, 2019, and expires on Aug. 31, 2024.

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Current permit documents

Permit reissuance

We are pleased to announce that the draft Water Treatment Plant General Permit is available for public comment. We invite comments on the draft permit documents beginning March 20, 2024 until May 3, 2024, 11:59 p.m. After the close of the comment period, we will publish a Response to Comments as an appendix to the fact sheet to address comments submitted during the public comment period.

Changes to the permit we are considering include:

  • Removing temporary groundwater discharge data collection requirements.
  • Adding an option for reduced monitoring following a consistent attainment of limits.
  • Requiring facilities to notify us when they start to use PFAS treatment technologies.
  • Administrative changes to improve clarity and readibility.
Anacortes Water Treatment Plant at night

Anacortes Water Treatment Plant

Draft permit documents

Public input 

We accepted comments from March 20 to May 3, 2024. You can view the comments we recieved through our online comment form. We held workshops/hearings on April 22 and 23. During the workshops, we explained the proposed changes to the permit and answered questions. The hearings began after the public workshop and ended when public testimony was complete. We are currently reviewing the comments we received and will respond to comments in an appendix to the permit fact sheet


March 2024 – May 2024: Formal public comment period on the draft permit
April 2024: Public workshops and hearings
August 2024: Decision on reissuance
August 31, 2024: Current permit expires

Water treatment plant reports 

Between 2014 and 2018, we reviewed data concerning water treatment plants in Washington, including:

  • Arsenic monitoring data provided by permittees.
  • Data about raw water sources, finished water production rates, volumes of wastewater discharged, and populations served for more than 900 water treatment plants statewide.

The two reports identified below summarize that work and our findings and conclusions.

Red building at Anacortes Water Treatment Plant

Anacortes Water Treatment Plant

Does my facility need this permit?

You need this general permit if your water treatment plant discharges wastewater to surface waters and:

  • Produces 35,000 gallons per day or more (monthly total divided by the number of days in the month) of finished drinking and industrial water.
  • The primary function of the facility is treatment and distribution of potable or industrial water.
  • Produces wastewater by filtration processes.
  • Is not a part of a larger permitted facility.

Operations not covered by this permit include discharge of wastewater that is:

  1. Produced by one of the following processes:
    • Ion exchange
    • Reverse osmosis
    • Slow sand filtration
  2. Sent to a publicly-owned treatment works delegated by Ecology.
  3. Released to land where runoff or overflow is impossible.

If any of these are the case, you may need an individual permit.

Permit application, forms, and resources

Contacts for more information

For permittees located in the following counties:

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

Marcia Porter
Permit Manager

For permittees located in the following counties:

Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, and Whitman

Whitney Richardson
General Permit Manager

For permittees located in the following counties:

Island, King, Kitsap, San Juan, Skagit, Snohomish, and Whatcom

Madison Diaz
Permit Manager

For permittees located in the following counties:

Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Kitsap, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, and Wahkiakum

Alisha Mckittrick 
Permit Administrator and Data Compliance Professional
564 999-3587