Oregon Public Broadcasting

The Oregon Public Health Division says some algae give off harmful toxins.

The state is warning people not to swim in ponds and lakes with scummy water or visible blooms this summer. Amelia Templeton reports.

The problem is cyanobacteria. It’s a family of resilient algae that’s been around for about three billion years.

It forms large blooms in fresh water in the summer.  Some types are harmless. But some cyanobacteria release a toxin that can affect the liver. And a second toxin harms the nervous system.

Dr. Dianna Conners is a toxicologist with the Public Health Office. She says swimming in an affected lake will probably just cause a rash. But swallowing the water could lead to worse symptoms, like tremors and vomiting.  Dianna Conners: "That’s why our primary concern is for small children and pets that might be swimming in the water and are more likely to ingest raw water than adults."

Conners says that the algae probably releases the toxins to protect itself from being eaten.

The algae killed at least one dog last summer.