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
Announcement phase (CR-101)
Filing date:
Nov. 19, 2025
Announcement documents
Rule development phase
Nov. 19, 2025 - Fall 2027Public input & involvement
Feb. 24 & 25, 2026 - Information webinar
During this webinar, we presented on our plan to update the surface water quality standards to address freshwater nutrient pollution and harmful algal blooms. This webinar covered the lake nutrient criteria rulemaking and the harmful algal blooms rulemaking. Topics we presented on included:
- An overview of the rulemaking process
- Harmful algal blooms: what they are and why they are an issue
- How humans and aquatic life are affected by nutrient problems in lakes and reservoirs
- Possible ways we will use science, including models, to develop water quality criteria to protect humans and aquatic life from these pollution issues
- Timeline and opportunities for future participation
Related links
Contact information
Marla Koberstein
Rulemaking Lead
marla.koberstein@ecy.wa.gov
360-789-3610
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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.