Chapter 173-201A WAC – Harmful Algal Blooms
Ecology is considering adding new freshwater recreational criteria to Chapter 173-201A WAC, Water quality standards in surface waters of the State of Washington. The criteria are 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 to protect people while swimming or doing other activities in and on water.
Following the U.S. Environmental Protection Agency (EPA) recommendations, we plan to consider freshwater criteria for two cyanotoxins: microcystins and cylindrospermopsin. We may also consider developing criteria for other toxins, including anatoxin-a and saxitoxin.
Rulemaking timeline
Announcement phase (CR-101)
Filing date:
Nov. 19, 2025
Announcement documents
Rule development phase
Nov. 19, 2025 - Fall 2026Public 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 harmful algal blooms rulemaking and the lake nutrient criteria 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.