Chapter 173-201A WAC (Aquatic Life Toxics Criteria)

Ecology is proposing revisions to chapter 173-201A WAC, Water Quality Standards for Surface Waters of the State of Washington. We are proposing the following revisions in this rulemaking:

  • Amending WAC 173-201A-240, Toxic substances, specifically updating aquatic life criteria in Table 240 and footnotes
  • Minor, non-substantive edits to rule language in WAC 173-201A-240 to correct typographical, calculation, and formatting errors, and to cite federal regulations for human health criteria where they apply for Clean Water Act purposes. 

We propose revisions to aquatic life toxics criteria to provide additional water quality protection for organisms that live in water. As part of this rulemaking, we:

  • Reviewed all of Washington’s current aquatic life toxics criteria to ensure they are consistent with nationally recommended water quality criteria issued by the Environmental Protection Agency (EPA)
  • Evaluated pollutant protection levels for endangered species in Washington waters
  • Evaluated new scientific data, methods, and modeling tools to update protection levels necessary for aquatic life in Washington’s surface waters
  • Propose adding new toxic substances to the water quality standards that EPA has recommended or that the state of Washington designates as high priority for the protection of aquatic life

Rulemaking timeline


Announcement phase (CR-101)

Filing date:
June 22, 2022

Announcement documents

Rule development phase

June 22, 2022 - Fall 2023

Public input & involvement

Oct. 10, 2023 - Preliminary rule webinar

We hosted a public webinar to discuss our current strategy to update the aquatic life toxics criteria. This is an opportunity to hear updates on the rulemaking and provide informal feedback to us.

During this webinar, we:

  • Discussed rule progress and timeline
  • Discussed the strategy for each aquatic life toxics criteria
  • Provided a preliminary view of aquatic life criteria values
  • Received feedback on preliminary proposal

View presentation slides (pdf)

April 20, 2023 - Informational webinar

We hosted a public webinar on our approach to this rulemaking and how we calculate new criteria. 

Topics we covered during this webinar:

  • How we calculate aquatic life toxics criteria, including using models
  • Evaluating protective criteria under the Clean Water Act and Endangered Species Act
  • Preliminary approach to developing criteria for pollutants with Endangered Species Act jeopardy calls
  • Preliminary rule strategy and updates on rule progress

View presentation slides (pdf)

Oct. 27, 2022 - Informational webinar

We held an informational webinar for the rulemaking. During this webinar, we provided an overview of:

  • Aquatic life toxics criteria – what they are and what they protect
  • History of the criteria in Washington
  • Strategy and scope of the rulemaking
  • Timeline and opportunities for public participation

View the presentation slides (pdf)

Rule proposal phase (CR-102)

Filing date:
Feb. 15, 2024

Rule proposal documents:


Comment period

Comments due May 7, 2024 at 11:59 p.m. (extended)

We accepted comments from 12:00 a.m. on Feb. 15, 2024, 11:59 p.m. on May 7, 2024. Ecology will review all comments received and plans to make a decision on rule adoption by Aug. 2024. See above for documents related to the Proposal Phase of the rulemaking.

View comments

Public workshop

At this workshop we gave a short presentation about the proposed rule, followed by a question and answer session. We did not take oral testimony at the workshop. Formal comments can be submitted online or during one of the hearings.

  • March 26, 2024, 1:30 p.m.

Public hearings

The hearings began with a short presentation and question and answer session, followed by the opportunity to provide testimony. The hearing concluded once everyone who wanted to provide testimony had the opportunity to do so. Written comments receive the same consideration as oral testimony.

  • April 4, 2024, 1:30 p.m.
  • April 10, 2024, 5:30 p.m.

View the public hearing presentation (pdf)

Webinars are an online meeting forum that you can attend from any computer using internet access.

Any information (e.g., personal or contact) you provide may be publicly disclosed and posted on the Internet.

To request ADA accommodations, contact Ecology’s ADA Coordinator by April 1, 2024, at:

Continuance filing (CR-102)

Filing date:
March 13, 2024

Continuance documents:

Comment period

Comments are due by May 7, 2024 (originally April 17, 2024). 

Additional languages

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To request ADA accommodation for disabilities, or printed materials in a format for the visually impaired, contact Ecology's ADA Coordinator by email at, or call 360-407-6831. People with impaired hearing may call Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.