Updates to the surface water quality standards

We update the surface water quality standards to incorporate the latest science and to meet our priorities and commitments regarding the standards.

Current actions 

The following information highlights the most recent actions related to the water quality standards in Washington.

Human health criteria

On June 30, 2021, the Environmental Protection Agency (EPA) filed a motion with the federal court requesting a legal “time out” so that:

  • EPA can propose a rule establishing protective federal human health criteria applicable to Washington’s surface waters.
  • Put that rule out for public comment.
  • Finalize a rule for Washington in 18 months.

While EPA cannot commit to what would be in this final rule, we expect that the criteria will reflect standards put into effect by EPA in 2016.

Until a new federal rule is in place the criteria that are in place are listed in WAC 173-201A-240, Toxic Substances Criteria. With the exception for the following chemicals: arsenic, methylmercury, and bis (2-chloro-1-methylethyl) ether, which continue to have federal criteria


  • Nov. 15, 2016 – EPA partially approved and partially disapproved certain human health criteria that Ecology submitted to EPA on Aug. 1, 2016
  • May 10, 2019 – EPA released a statement that they are reversing their 2016 decision and approving the human health criteria standards Washington submitted in 2016.
  • July 23, 2019 – EPA announced a draft rule to withdraw the federal water quality standards for certain human health criteria in Washington (40 CFR 131.45).  
  • April 16, 2020 – EPA announced their final rule to withdraw the federal water quality standards for certain human health criteria in Washington (40 CFR 131.45), no effective date stated.
  • May 13, 2020 – EPA published the final rule in the Federal Register to withdraw the federal water quality standards for certain human health criteria in Washington (40 CFR 131.45). The final rule went into effect on June 12, 2020.
  • June 30, 2021 – EPA files a motion with federal court to provide time to propose new human health criteria for Washington.

The following are responses to EPA's actions from Ecology and other state agencies along with our press releases and formal comments on the rulemaking. 

Current rulemaking

We use the rulemaking process to meet our priorities and commitments regarding the standards.

Recently completed rulemaking

Triennial review 

Federal regulations require that we periodically hold public hearings to review surface water quality standards. This process is called a triennial review. This review gives us an opportunity to discuss priorities and commitments to update surface water quality standards. 

2021 Triennial Review

We have continually updated the water quality standards since the last triennial review in 2010. More details in the draft work plan.

From July 20 until Sept. 16, 2021, we accepted comments on our draft work plan of actions we expect to take related to Washington surface water quality standards between 2022 – 2024. Learn more about this Triennial Review in our focus sheet.

We have not conducted a triennial review since 2010 because we have been in continual rulemaking efforts for the water quality standards since then.

We held an online public hearing on Sept. 9, 2021.​

Next steps

After reviewing the comments received, we will provide a responsiveness summary and final work plan, which we will submit to the Environmental Protection Agency for review. 

Rulemaking process

When it is necessary to update the standards we go through the rulemaking process. We select the topics for rulemaking based on which actions will make the greatest environmental and/or administrative benefits.

Topics are prioritized based on:

  • The expected environmental benefits.
  • Changes in science
  • Federal mandates or legal requirements.
  • Requests for specific updates.
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