When in Doubt, Stay Out!

Cyanobacteria Harmful Algae Blooms (CyanoHABs)

Cyanobacteria blooms happen naturally in Oregon lakes and rivers. However, some blooms produce toxins that can make people and animals sick - these are called cyanobacteria harmful algae blooms (cyanoHABs).

OHA reviews available information on cyanoHABs in the state. If a bloom poses a health risk, we can issue a recreational advisory or precation.

Most waterbodies in Oregon are not monitored for cyanoHABs. Know the signs of a bloom before you take the plunge! If you are not sure if a lake or river has a cyanoHAB, it is best to stay out and keep pets away.

When in doubt, stay out!

Current Recreational CyanoHAB Advisories

The most current information on recreational advisories issued and lifted throughout the season.

View a map and table of current recreational use health advisories for cyanobacteria and cyanotoxins

Recreational CyanoHAB Advisory Archive

A record of recreational use health advisories issued in Oregon since 2007.

Browse the summaries and view the data for each year

Education and Outreach

Brochures, posters, fact sheets and journal articles that cover basic information, human and animal health, fish consumption and environmental concerns.