Science & Environment

Recreation on parts of Willamette River deemed unsafe because of toxic algae

By Monica Samayoa (OPB)
Sept. 1, 2021 9:46 p.m.

The Oregon Health Authority is urging people to avoid recreating in parts of the Willamette River in Portland because of harmful algal blooms.

On Tuesday the agency issued a recreational health advisory for Ross Island Lagoon and Holgate Channel as cyanobacteria, or the blue-green algae, was detected in the water.

A mostly-blue river adjacent to a strip of land and green water on the other side.

An aerial view on Aug. 19, 2021, of algal blooms in the Ross Island Lagoon, to the right of the Willamette River's mainstem.

Brandon Swanson / OPB

The toxic algae can make people sick if ingested or cause skin, ear and eyes irritation if exposed to it. The agency is asking the public to avoid swimming and any recreational activity like water skiing or power boating that may cause splashing that could be accidently ingested. Drinking the toxic water could lead to symptoms like headaches, cramps, nausea, dizziness and fever.


Willie Levenson is a Portland activist who heads an effort to get more people to recreate in the Willamette River as cleanup efforts over the year have made it once again safe to swim and paddle in. He said it was devastating to see the return this year of blue-green algae, but not surprising, given this summer’s hot weather.

“It takes three things for a harmful algae bloom to form, slow moving water, warm water and nitrogen load,” said Levenson, the founder and self-titled “ringleader” for the Human Access Project.

Levenson said the organization has been working since 2015 to reduce the formation of harmful algae blooms. But the effects of climate change threaten those efforts unless new efforts are made to keep the Willamette safe for recreation.

“Unless we put some work in and are committed to finding a solution to this problem, the Willamette River over the next 10 to 20 years as climate changes and the river gets warmer with having less snowpack, this is something that could really impact the livability for our community,” he said.

OHA says children and pets are at a higher risk of illness if exposed to toxins. If pets ingest the toxins, they are at extreme risks of getting ill and dying from intoxication.

Toxins cannot be removed by boiling, filtering, or treating water with camping-style filters.