Toxic Algae Advisories

Cyanobacteria blooms may look like mats floating in the water or stuck on the bottom or the shore. Be on the lookout for waters that look suspicious—foamy, scummy, thick like paint, pea-green, blue-green or brownish red, or bright green cells suspended in the water column. 

Not all Oregon waterways are monitored for cyanobacteria. This resource can help you tell the difference between normal algae and toxic algae, but when in doubt, stay out!

Health advisories for toxic algae levels have been issued for the following bodies of water in Oregon.

Active advisories

Owners should be aware of the potential exposure to their pets while at these areas, especially shallow, marshy areas where cyanobacteria blooms can form. Cyanobacteria can be present on green algae, growing from the sediment or on rocks. Pets, livestock and people should avoid contact with the affected water. Drinking water directly from areas affected by a bloom is especially dangerous. Toxins cannot be removed by boiling, filtering or treating water with camping-style filters.

• Big Cliff Reservoir and Detroit Reservoir in Marion County Updated 8.30.24 
  See the map for the specific area. 
• Luckiamute Landing State Natural Area in Linn County (precautionary warning) 8.30.24
• Devil’s Lake in Lincoln County 8.29.24
• Willow Creek Reservoir in Morrow County 8.19.24
• Wapato Marsh at Oaks Bottom Wildlife Refuge in Multnomah County 8.7.24
• Hells Canyon Reservoir in Baker and Wallowa Counties (issued by state of Idaho) 8.5.24
• Brownlee Reservoir in Baker County (issued by state of Idaho) 8.5.24
• Thief Valley Reservoir in Baker and Union Counties 8.5.24

Lifted advisories

Illness in pets can still occur at lower toxin values, so please continue to exercise caution with pets at these areas:

• North Santiam River, from the confluence with the Little North Fork Santiam River in Mehama up to Big Cliff Reservoir and from mouth of the Little North Fork Santiam River to Detroit Reservoir in Marion/Linn Counties. Values are below recreational guidelines for people. Dogs should still stay out of the water. See the map for the specific area. 
• Lake Billy Chinook & Lake Simtustus in Jefferson County — Values below recreational guidelines for people and dogs.
• Cottonwood Reservoir in Harney County — Values below recreational guidelines for people and animals.
• McKay Reservoir in Umatilla County  — Values below recreational guidelines for people and dogs.
• Fairview Lake in Multnomah County — This advisory was lifted because values are below recreational guidelines for people. Dogs should still stay out of the water.
• Cold Springs Reservoir in Umatilla County
• Turner Lake in Marion County  — Values below recreational guideline for people and dogs.

Permanent advisory

• South Umpqua River: The advisory covers the South Umpqua River from Canyonville downstream to the confluence with the mainstem Umpqua River, and the mainstem Umpqua River downstream past Elkton to Sawyers Rapids. Pools in the bedrock along the rivers edge are known to develop cyanobacteria (blue-green algae) blooms that can be harmful to pets and people if accidental ingestion occurs.

Advisories in surrounding states

• California
• Idaho
• Nevada
• Washington

Children and pets are particularly susceptible to this toxin

The most common toxins in harmful algal blooms in Oregon are microcystins and cylindrospermopsin. Exposure to these toxins can produce symptoms of numbness, tingling and dizziness that can lead to difficulty breathing or heart problems and require immediate medical attention. Symptoms of skin irritation, weakness, diarrhea, nausea, cramps and fainting should also receive medical attention if they persist or worsen. Children and pets are particularly susceptible.

Swallowing or inhaling water droplets should be avoided, as well as skin contact with water by humans or animals. Drinking water from these bodies of water is especially dangerous. Oregon Public Health officials advise campers and other visitors to recreation sites that toxins cannot be removed by boiling, filtering or treating the water with camping-style filters.

Oregon Public Health recommends that people who choose to eat fish from waters where algae blooms are present should remove all fat, skin and organs before cooking since toxins are more likely to collect in these tissues.

A hazard for dogs

Dogs have become very sick and even died after swimming in and swallowing water affected by toxic algae. If you find thick, brightly colored foam or scum at a lake, pond or river, don’t let your pet drink or swim in the water. Avoid contact with the water, as toxins can be absorbed through the skin.

Symptoms in dogs

Exposure to toxic blue-green algae can result in:

• Weakness or collapse
• Nausea, vomiting
• Excessive drooling
• Weakness, fatigue, stumbling
• Abdominal pain
• Diarrhea
• Difficulty breathing
• Shaking, trembling
• Seizure like activity: Tremors, rigidity, paralysis
• Liver failure

If your dog goes into the water:

• Don’t let your pet lick its fur.
• Wash your pet with clean water as soon as possible.
• If your dog has symptoms such as drooling, weakness, vomiting, staggering and convulsions after being in water, seek immediate veterinary care. Acute, life-threatening symptoms from cyanobacterial toxins often develop rapidly. Death can occur within minutes to hours after exposure.

For more information, contact the Harmful Algae Bloom Surveillance program at (971) 673-0400.