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

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

  • Amending WAC 173-201A-240, Toxic substances, specifically aquatic life criteria, including, but not limited to, Table 240 and footnotes
  • Minor, non-substantive edits to rule language in WAC 173-201A-240 to correct typographical, calculation, and formatting errors

We may amend other sections of Chapter 173-201A WAC as necessary to support any revisions to the sections noted above.

We are considering revisions to aquatic life toxics criteria to provide additional water quality protection for organisms that live in water. We will:

  • Review 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)
  • Evaluate pollutant protection levels for endangered species in Washington waters
  • Evaluate new scientific data, methods, and modeling tools to update protection levels necessary for aquatic life in Washington’s surface waters
  • Consider 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)

Additional languages

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