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

Timeline

Announcement phase (CR-101)

Filing date:
Nov. 19, 2025


Announcement documents

Rule development phase

Nov. 19, 2025 - Fall 2026

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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.