ross island algae.jpg

Algae was recently spotted in the Willamette River in the Ross Island Lagoon.The algae will be tested to determine if it is toxic.

(CourtesyKate Ross/Willamette Riverkeepers)

Blue-green algae found last week in the Willamette River's Ross Island Lagoon has reached toxic levels for humans and pets.

What you should know

The Oregon Health Authority issued an algae warning for the Willamette River at the Ross Island Lagoon, including the mouth where it enters the Holgate Slough.

1. Avoid swallowing or inhaling droplets of water when swimming, water skiing or power boating in the area.

2. Don't drink or cook with river water from the area and beware that toxins remain even after boiling, filtering or treating the river water.

3. Remove all fat, skin and organs before cooking any fish or crayfish from the river where the algae is blooming.

For more information, call 971-673-0400 or

harmful algae blooms.

-- Oregon Health Authority

The Oregon Department of Environmental Quality tested algae from the lagoon south of the Ross Island Bridge and from the Riverplace Marina this week, said Brian Boling, the agency's laboratory program manager.

While the bright green algae found in the lagoon tested positive for toxins, he said, the samples found around the marina did not. However, he added, hot summer conditions -- and their impact on river levels and water temperature - could lead to more toxic blooms.

Boling said the agency will test the river again on Monday.

"We're kind of at a wait and see period," said Boling, noting that toxic blooms were found at the same places in the river last August. So far, he said, the situation this year isn't as bad.

Blue-green algae produces poisons that could cause serious illness or death in pets, according to the Oregon Health Authority's website. For humans -- and children, especially -- toxic algae can also cause dizziness, vomiting or skin rashes, among other adverse effects. The most severe reactions occur when large amounts of water are swallowed.

People experiencing diarrhea, vomiting, cramps or fainting should see their doctor.

The health authority issued a harmful algae advisory late Thursday afternoon. The advisory warns swimmers to stay away from slow-moving water that is "foamy, scummy, thick like paint, pea-green, blue-green or brownish-red." See the box at left for more details.

The OHA has issued multiple algae bloom advisories in recent months. One was issued in May for Detroit Lake, located about 45 miles southeast of Salem, and another last month for Lake Billy Chinook Reservoir southwest of Madras in Jefferson County.

Toxic algae was found in the Willamette River in September 2014, prompting a weeks-long advisory.

See below for a video Willamette Riverkeeper Outreach and Education Coordinator Kate Ross took while paddling the lagoon.

-- Laura Gunderson

503-221-8378; @lgunderson