Beware of cyanobacteria blooms this summer

As summer approaches, and more communities and recreational areas around the state begin reopening amid the COVID-19 outbreak, Oregon Health Authority (OHA) reminds people heading outdoors to be on the look-out for cyanobacteria blooms that can produce toxins when recreating in Oregon lakes, rivers and reservoirs.

Cyanobacteria are beneficial bacteria found in all freshwater, worldwide. Under the right conditions—when weather, sunlight, water temperature, nutrients and water chemistry are ideal—cyanobacteria can multiply into blooms in any water body. Many blooms are harmless, but some can produce cyanotoxins that make people and animals sick.

Exposure to cyanotoxins occurs when water is swallowed while swimming, or when water droplets are inhaled during high-speed activities such as water-skiing or wakeboarding. Symptoms of exposure to cyanotoxins include diarrhea, cramps, vomiting, numbness, dizziness and fainting. Although cyanotoxins are not absorbed through the skin, people with sensitive skin can develop a red, raised rash when wading, playing, or swimming in or around a bloom.

Children and pets are particularly sensitive to illness because of their size and activity levels. Dogs can get extremely ill and even die within minutes to hours of exposure to cyanotoxins by drinking the water, licking their fur, or eating the toxins from floating mats or dried crust along the shore.

Only a fraction of freshwater bodies in Oregon are monitored for cyanotoxins. Due to continued safety concerns related to COVID-19, OHA expects visual monitoring and sampling of affected water bodies to be less than normal. For this reason, it will be even more important as more recreational areas open and the summer recreation season begins, for people to visually observe any water body they choose to recreate in before taking the plunge.

OHA recommends that everyone stay out of water that looks foamy, scummy, thick like pea-green or blue-green paint, or where brownish-red mats are present. If you are unsure, follow OHA’s guidance of “When in doubt, stay out.”

To learn if an advisory has been issued or lifted for a specific water body, visit the Harmful Algae Bloom website or call the Oregon Public Health Division toll-free information line at 877-290-6767.