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Cyanobacteria Season

As temperatures heat up during spring and summer, be on the watch for cyanobacteria blooms when recreating in Oregon lakes, rivers and reservoirs.

When a cyanobacteria bloom is detected and lab results show that cyanobacteria or cyanotoxins are present at levels over OHA recreational use values, OHA issues a recreational use health advisory warning people to stay out of affected water to avoid illness.

We send recreational use health advisories via the media and email, and we post this information on the website. Sign up to receive email alerts.


Exposure to cyanobacteria and cyanotoxins can be serious and result in a range of symptoms including skin rash, diarrhea, cramps, vomiting, numbness, dizziness and fainting. Children, people with weakened immune systems and pets are most vulnerable to illness.

Pets are at risk, too

Due to their size and level of activity, dogs are very susceptible to the affects of cyanotoxins. In the past, we’ve had reports of dog deaths due to exposure to bloom-affected water. OHA and Douglas County Health Department conducted specific outreach efforts along the South Umpqua River and mainstem Umpqua River following widespread publicity of dog deaths in the area. The concern triggered by this event has increased awareness among pet owners who are taking additional action to protect their pets. 

When to avoid water contact

Because only a fraction of Oregon’s fresh waters are visually monitored and sampled, the public can’t count on being notified about all cyanobacteria blooms, so there are certain conditions you can identify to stay safe and healthy. If the water smells bad or looks foamy, scummy, thick like paint and pea-green, blue-green or brownish-red in color, it’s best to stay out.

Funding for the program through the U.S. Centers for Disease Control and Prevention ended as of September 2013. Although work performed in this program has no funding source, staff continue to provide core program elements necessary to alert the public about blooms in order to protect public health.

Be safe,

Curtis Cude
Program Manager
Environmental Public Health
Public Health Division
Oregon Health Authority

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