Washington State Department of Health has developed guidelines for microcystins, anatoxin-a, cylindrospermopsin, and saxitoxin for those who manage recreational water bodies. The recommended recreational guidance values for those four cyanotoxins are 8 μg/L, 1 μg/L, 15 μg/L, and 75 μg/L, respectively.
See the complete report, Recreational Guidance for Microcystins, Anatoxin-a, Cylindrospermopsin and Saxitoxin (PDF).
Tier I. A WARNING sign is posted if microcystins levels are 8 μg/L or higher, anatoxin-a levels are 1 μg/L or higher, cylindrospermopsin levels are 15 μg/L or higher, and/or saxitoxin levels are 75 μg/L or higher. DOH recommends that lakes are sampled weekly, at a minimum, with the WARNING sign posted as long as toxin concentrations remain above thresholds.
Tier II. Under certain circumstances, a local health jurisdiction may close a lake with unusually high microcystins, anatoxin-a, cylindrospermopsin, or saxitoxin concentrations. At the discretion of the local health jurisdiction or appropriate agency, a water body can be posted as DANGER – Closed. Examples include very dense blooms covering an entire lake, confirmed animal illnesses or death, and reported human illness.
Search to see which water bodies have toxic algae blooms or report and have blooms tested through the Washington State Toxic Algae Website.