OHA Lifts Cyanobacteria Health Advisory for Willamette River, but Warns Dog Owners to Look for Algae Blooms

“We never use the word safe. No water body is ever safe.”

Although the weather in recent weeks has noticeably cooled, a question remains on the minds of many recreating Portlanders: When can I put my dog in the river?

On Tuesday, Oct. 12, the Oregon Health Authority lifted a health advisory in place for the Ross Island lagoon and Holgate Channel in the Willamette River. But don’t go running to the river with your dog just yet.

The answer, according to OHA: It is never 100% safe to put your dog in the river.

This past summer, an early August advisory warned Portlanders that the Willamette River’s cyanotoxin bacteria readings indicated a toxic level for dogs.

The advisory spanned 14 miles of the Willamette, from Ross Island to the Sauvie Island Bridge. When another advisory followed later in August, for humans, it was only relegated to the Holgate and Ross Island areas of the river—and that’s the one the OHA just repealed.

The OHA only tests for levels that might be dangerous to humans and, even then, the agency only tests when it receives credible notification of a troubling bloom. These reports are often made by OHA or Department of Environmental Quality employees noticing the blooms on a run or during their commute.

“Water body managers don’t have the resources to constantly sample the river,” natural resource specialist Rebecca Hillwig tells WW.

Still, even the 14-mile pet hazard area was more guidance, not a hard and fast boundary. “I know there were blooms beyond that because homeowners have sent me pictures,” Hillwig says.

With the lifting of the OHA advisory, Hillwig says pet owners should become familiar with what blooms look like and stay aware of their surroundings.

“When recreating, people and especially small children and pets should avoid areas where the water is foamy, scummy, thick like paint, pea green or blue green, or if thick brownish-red mats are visible or bright green clumps are suspended in the water,” the Oct. 12 release reads.

In animals, toxicity symptoms appear very similar to food poisoning and can set in quickly: vomiting, heart palpitations, heavy breathing, disorientation. Animals displaying such symptoms should be taken to the vet right away.

“Cyanobacteria can grow under the ice. They’re really hardy,” Hillwig said when asked whether cooling temperatures might mean less bacteria. “There is chemistry that they prefer, but that doesn’t mean they can’t create a bloom under cooler conditions. We never use the word safe. No water body is ever safe.”