Updates to the surface water quality standards

Visit the rulemaking page and read our blog for more information.

We are considering adding new freshwater recreational criteria for toxins produced during harmful algal blooms. Some algal blooms have cyanobacteria that produce toxins that are particularly harmful to humans.  

We are considering setting recreational criteria for toxins produced during harmful algal blooms (HABs) to protect people while swimming or doing other activities in and on water. 

Visit our rulemaking webpage and read our blog for more information.

We are considering revisions in our standards to develop water quality criteria that will protect aquatic life, recreation, and drinking water sources in lakes and reservoirs from nutrient pollution. Excess nutrients can contribute to harmful algal blooms, which can lower oxygen levels in the water, negatively impact recreation, and overall reduce the health of people and the environment. 

We adopted revisions to address the Environmental Protection Agency’s 2021 disapproval of Washington's natural condition provisions in our standards, including for fresh and marine dissolved oxygen and temperature (excluding lakes). Visit the rulemaking page for more information.

These rule amendments have not yet been approved by EPA for use in Clean Water Act programs.

Also, we added a new section in the rule to define a method called a “performance-based approach” to determine natural conditions criteria values.  We have published the final methods document that provides the information and process we must follow to calculate natural conditions site-specific criteria.

This document is not rule language, but it supports the rulemaking on natural conditions. This document currently covers marine dissolved oxygen natural conditions. We anticipate future chapters to address other conventional pollutants. We accepted comments on the on the revised draft document from March 25 until May 22, 2025.

You can view:

• Our response to comments received on the second draft methods document
• Comments we received on the second draft methods document
• Public hearing presentation slides (May 15, 2025)

We submitted the natural conditions rulemaking packet and final performance-based approach methods document to EPA for review on Sept. 30, 2025.

On Nov. 19, 2021, EPA notified Ecology of a disapproval on our previously approved natural condition provisions in our Surface Water Quality Standards. The natural conditions provisions recognize that some water bodies have poorer water quality due to natural (not human caused) conditions like climate or landscape. Although these provisions have been a part of state water quality standards since 1967, EPA agreed to reconsider whether this part of our standards are currently sufficient. As a result, EPA disapproved the following sections of our surface water quality standards:

• A general provision that allows a water body’s natural conditions to serve as the water quality standard. [WAC 173-201A-260(1)(a)] 

• A specific provision that sets the temperature requirement of how cool a water body would be without human alterations. This provision also limits temperature increases caused by human activity to less than 0.3 degrees Celsius. [WAC 173-201A-200(1)(c)(i); -210(1)(c)(i))]

• A specific provision that sets the dissolved oxygen requirement to be at the highest levels a water body can achieve without human alterations. This provision also states that human activity cannot cumulatively cause dissolved oxygen in a water body to decrease more than 0.2 mg/L. [WAC 173-201A-200(1)(d)(i); -210(1)(d)(i)]

The numeric water quality criteria for temperature, dissolved oxygen, and all other parameters still remain in place. This disapproval only removes our ability to include the natural variations of water conditions in some of our water quality decisions.

We are considering revisions to address EPA's 2021 disapproval of Washington's natural condition provisions in our standards, including for fresh and marine dissolved oxygen and temperature (excluding lakes).

In addition, on Sept. 30, 2021, EPA notified Ecology of a disapproval on our previously approved water quality standards provision that allows short-term modifications of the standards for some qualifying activities in WAC 173-201A-410. In 2006, we added additional options to allow the standards to be modified during major watershed restoration activities that may take a longer amount of time than previously defined as short-term, this is no longer allowed using the short-term modification provision.

In this action, EPA also disapproved water quality temperature limits on discharges that create a thermal plume in the receiving water body [WAC 173-201A-200(1)(c)(vii)(C); -200(1)(c)(v)(C)]. Although this limit is used for some discharges, protective numeric temperature limits still apply. 

Visit the rulemaking page for more information.

We adopted revisions to the aquatic life toxics criteria to provide additional water quality protection for organisms that live in water. 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.

These rule amendments have not yet been approved by EPA for use in Clean Water Act programs.

Read our blog and news release to learn more about aquatic life toxics criteria.

Visit the rulemaking page for more information.

We adopted changes to Washington's surface water quality standards. These changes better protect water quality and physical habitat for incubating eggs and young salmon in rivers and streams. The changes will further ensure salmon nests, called redds, have enough oxygen to support early life stages of salmon. We also added better protection to these early life stages of salmon from the harmful effects of too much fine sediment that can clog important spawning gravels where redds are located.

These rule amendments have not yet been approved by EPA for use in Clean Water Act programs.

Read our blog to find out more about how this rulemaking better protects salmon.

Visit our rulemaking page for more information.

We made changes to the aquatic life designated use of salmonid spawning, rearing, and migration on the Chelan River through a use attainability analysis (UAA) and rulemaking process. These adopted changes to the designated uses and criteria for the Chelan River were in response to a rulemaking request from the Public Utility District No. 1 of Chelan County (Chelan PUD).

Chelan PUD returned year-round flows to the Chelan River and established habitat along the river, and conducted a 10-year monitoring and adaptive management program to meet spawning, survival, and habitat use objectives for Chinook salmon, steelhead, and resident fish. Following this work, Chelan PUD submitted a request for a Use Attainability Analysis rulemaking for the aquatic life designated use on the Chelan River to better reflect current and historical uses.

A UAA is an approved water quality tool in Washington’s surface water quality standards (WAC 173-201A-440) and is used for removing or revising a designated use for a water body only if that use is not existing or attainable. A UAA is a scientific assessment of the physical, chemical, biological, and economic factors that may affect the attainment of the use.

These rule amendments have not yet been approved by EPA for use in Clean Water Act programs.

See our rulemaking page for more information.

Ecology adopted amendments to the human health criteria and associated footnotes in Table 240 of WAC 173-201A-240, to incorporate existing federal human health criteria for Washington into the state water quality standards.

Read our news release to find out more about this rule update.

On Nov. 14, 2022, the Environmental Protection Agency (EPA) announced a final rule to adopt human health criteria for the state of Washington's waters. On Nov. 18, 2022, EPA published the final rule in the Federal Register. The rule goes into effect on Dec. 19, 2022.

This rulemaking returns the human health criteria to what EPA had originally approved in 2016, before they changed in 2020. EPA took comments on a draft rule from March 28, 2022 until May 31, 2022.

Timeline of EPA actions:

• 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.
• March 28, 2022 – EPA proposed a rule to promulgate human health criteria for the state of Washington’s waters that EPA had originally promulgated in 2016 but later removed in 2020.
• Nov. 18, 2022 – EPA published the final rule in the Federal Register to promulgate human health criteria for Washington's waters. The final rule goes into effect on Dec. 19, 2022.

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.

• July 2, 2021 Director Watson statement 
• April 17, 2020 Director Watson statement
• Oct. 6, 2019 Director Bellon written comments
• Sept. 25, 2019 Director Bellon's testimony at EPA public hearing
• Aug. 28, 2019 webinar public hearing testimony
• July 22, 2019 Director Bellon letter about EPA public hearings
• June 12, 2019 Director Bellon letter to EPA
• June 6, 2019 Attorney General news release
• May 10, 2019 Governor and Attorney General response 
• May 7, 2019 Director Bellon letter to EPA
• April 10, 2019 Ecology news release 

Read the Outstanding Resource Waters rulemaking for more information.

We adopted outstanding resource water designations for the following water bodies under WAC 173-201A-330 (Antidegradation Tier III – Protection of Outstanding Resource Waters):

• Soap Lake (Grant County)
• Napeequa River (Chelan County)
• Green River (Lewis and Skamania counties)
• Cascade River (Skagit County)

Read our blog to learn more about outstanding resource water designations.

Visit the rulemaking page for more information. 

This rulemaking adopted multiple revisions including changes to the numeric criteria for total dissolved gas in the Snake and Columbia rivers. We adopted changes to the total dissolved gas criteria to allow more water to spill over dams to help salmon migrate. Read our blog to learn about the environmental impacts of allowing more water over the dams.

The Triennial Review is a public involvement opportunity that helps inform and prioritize revisions to the surface water quality standards for the next three years. This is not a rulemaking process; rather, it is a planning process to help guide actions necessary to keep the standards current.

During the Triennial Review, we:

• Review the water quality standards to identify needed updates based on the Environmental Protection Agency recommendations, new scientific information, and agency priorities
• Draft a workplan that outlines our priority actions for the next three years
• Get feedback on the plan and make revisions based on comments we receive
• Send the final plan to the EPA
• Begin rulemakings and other actions as listed in our workplan

Each rulemaking project identified as a priority will have its own public process to formally comment on proposed rule changes, in accordance with Washington’s Administrative Procedure Act (APA) at Chapter 34.05 Revised Code of Washington (RCW) and the Code of Federal Regulations (CFR) at 40 CFR part 25. Priorities identified in a triennial review will be incorporate as commitments in Ecology's Performance Partnership Agreement with EPA.

View our 2022 Triennial Review report that outlined actions we planned for 2022 through 2024.