As the weather warms up, state agencies are keeping an eye on Oregon’s lakes, rivers, and reservoirs for toxic cyanobacteria blooms, also known as harmful algae blooms.
Cyanobacteria are natural and found in many freshwater places. Most of the time they’re harmless, but sometimes they can grow quickly and make toxins that can make people and animals sick.
When the water gets warm and sunny, blooms are more likely. This is also when many of us head outside to swim, boat, and cool off. That’s why Oregon Health Authority (OHA) and the Department of Environmental Quality (DEQ) are starting their yearly monitoring.
People can get sick if they swallow water with toxins or breathe in water spray during activities like water‑skiing. Symptoms can include diarrhea, cramps, vomiting, numbness, dizziness, and fainting.
Although the toxins are not absorbed through the skin, people with sensitive skin can develop a rash when wading, playing, or swimming in or around a bloom.
Children, pets, livestock, and wildlife are at higher risk. Dogs can get very sick or even die quickly after drinking or licking water with toxins. Get your pet to a vet right away if they show signs like vomiting, trouble breathing, or trouble walking.
Only a few places in Oregon are tested for toxins, so it’s important to look at the water before you go in. Stay out of water that looks foamy, scummy, pea‑green, blue‑green, or has brown or red mats. Blooms can also wash up on shore, so avoid those areas too.
If you are looking for visual examples, you can find pictures of algae blooms in the Algae Bloom Photo Gallery or watch an explainer video on blooms at OHA’s official YouTube channel. If you are unsure, follow OHA’s guidance of:
“When in doubt, stay out.”
You can still enjoy the outdoors—camping, hiking, picnicking, and bird‑watching are safe. Activities like kayaking, canoeing, fishing, and boating are usually okay as long as you avoid creating spray. Fish are safe to eat if you clean them well and remove the fat, skin, and organs.
To see if a water advisory is in place, visit the Harmful Algae Bloom website or call OHA at 877‑290‑6767. To report an illness, call OHA at 971‑673‑0440. For campground or lake information, contact the local management agency.