Chapter 173-201A WAC – Lake Nutrient Criteria

Ecology is considering revising Chapter 173-201A WAC, Water Quality Standards for Surface Waters of the State of Washington 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 will review the U.S Environmental Protection Agency’s final recommended criteria for total nitrogen, total phosphorus, and chlorophyll a, in addition to any other up-to-date information, to develop protective criteria for Washington’s lakes and reservoirs.

Rulemaking timeline

Timeline

Announcement phase (CR-101)

Filing date:
Nov. 19, 2025


Announcement documents

Rule development phase

Nov. 19, 2025 - Fall 2027

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Accessibility

To request ADA accommodation for disabilities, or printed materials in a format for the visually impaired, contact Ecology's ADA Coordinator by email at ecyadacoordinator@ecy.wa.gov, 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.