Hells Canyon Reservoir algae bloom status

Hells Canyon Reservoir algae bloom history

The Oregon Health Authority has issued 5 advisories and precautions for Hells Canyon Reservoir since 2019, covering 5 of the 7 years from 2019 to 2025.

5 were recreational use health advisories, issued when toxins or cyanobacteria are above Oregon's guideline values for people.

Blooms have been recorded every year for the last 4 years in the data.

Reports have risen in the last three years compared with the three before.

Recent Hells Canyon Reservoir algae reports

What the Oregon results mean

The Oregon Health Authority issues two kinds of notice for waterbodies it monitors.

Health advisory

Toxins or cyanobacteria are above Oregon's recreational guideline values for people. Avoid swimming and water activities that could make you swallow water, and keep pets and children out.

Precaution

Toxins are below the guidelines for people but still above Oregon's guideline values for dogs. Keep pets away from blooms and avoid foamy, scummy or paint-like water.

Is Hells Canyon Reservoir safe for dogs?

Dogs are at the greatest risk from toxic algae. They swallow water while swimming, eat scum on the shore and lick algae off their fur afterwards, and a small amount can kill a dog within hours. With blooms recorded in 5 different years here, take particular care at Hells Canyon Reservoir.

• Keep your dog on a lead near water that looks green, scummy, foamy or discoloured, and away from algae washed up on the shore.
• If your dog gets in, rinse it straight away with clean water and don't let it lick its coat.
• Call a vet immediately if your dog vomits, drools, has diarrhoea, staggers, shakes or seems weak after being near the water.

Read the full guide to toxic algae and dogs: symptoms, what to do in the first minutes and how vets treat it.

Health effects of toxic algae

Blue-green algae (cyanobacteria) can produce toxins that affect the liver, nervous system and skin. Swallowing water during a bloom can cause stomach pain, vomiting and diarrhoea. Skin contact can cause rashes, and breathing spray from the water can irritate the eyes, nose and throat. Children are at higher risk because they are smaller and more likely to swallow water.

How to spot a bloom

Toxic blooms can look like pea soup, spilled paint or green streaks on the surface, and they can also be blue, brown, white or red. Scum often collects along the shore downwind. If you can't see your feet in knee-deep water, or you aren't sure, stay out.

Don't drink untreated lake water, and don't boil it to make it safe: boiling doesn't destroy algal toxins. If you feel unwell after contact with the water, contact a doctor or Poison Control on 1-800-222-1222.

Nearby lakes with algae reports

• Brownlee Reservoir31 km away, 8 reports, last in 2025

All Baker County lakes with algae reports

Questions about Hells Canyon Reservoir

Is there algae in Hells Canyon Reservoir right now?

Oregon issued a health advisory for Hells Canyon Reservoir in 2025, listed on 18 November 2025. Oregon publishes its data once a year, so for today's conditions check the OHA current advisories page and the signs at the shore.

When was the last algae bloom at Hells Canyon Reservoir?

The most recent entry in Oregon's data is from 18 November 2025: a health advisory.

Has Hells Canyon Reservoir had toxic algae before?

Yes. Blooms are recorded in 5 of the 7 years from 2019 to 2025.

Can dogs swim in Hells Canyon Reservoir?

Keep dogs out of the water whenever a bloom is reported or the water looks green, scummy or discoloured. Dogs are the animals most often killed by algal toxins because they swallow water and lick their fur. If your dog swims in water that might have algae, rinse it with clean water and call a vet if it vomits, drools, staggers or seems weak.

Can you eat fish caught in Hells Canyon Reservoir during a bloom?

If you keep fish caught during a bloom, health agencies advise removing the guts and liver and rinsing the fillets in clean water before cooking, because toxins collect most in the organs. Some agencies advise not eating fish from an active bloom at all, so follow local guidance.