As families across Jefferson County and greater Central Oregon head into what is typically the busiest summer weekend at Lake Billy Chinook, the Oregon Health Authority (OHA) is maintaining a recreational use health advisory for the reservoir due to dangerously elevated levels of cyanotoxins in the water.

The advisory, which was first issued on June 12 and has since been expanded to cover the entire lake, urges the public to avoid activities that involve swallowing water or inhaling water droplets — including swimming and high-speed water sports — wherever algae blooms are visible.

What Are Cyanotoxins?

Cyanotoxins are poisons produced by cyanobacteria, commonly known as blue-green algae. The microscopic organisms thrive in warm, slow-moving water during hot weather — exactly the conditions Lake Billy Chinook has been experiencing this summer. When bloom concentrations rise above Recreational Use Values (RUVs), the state issues health advisories.

The toxins are not absorbed through the skin, but can cause a rash in people with skin sensitivities. Swallowing contaminated water is far more serious, and can produce symptoms ranging from stomach cramps, nausea, and diarrhea to numbness, tingling, dizziness, and shortness of breath. Severe cases may require medical attention.

Danger to Pets

OHA is issuing a particular warning to pet owners. Dogs can become seriously ill or die within minutes to hours of exposure, whether from drinking the water, licking their fur after contact, or consuming dried algae mats along the shore. Keep dogs on leashes and away from the water’s edge.

“If a dog exhibits symptoms [such as] difficulty walking, seizures, lethargy, and loss of appetite — veterinary treatment should be sought as quickly as possible,” OHA stated.

Boating and Fishing

Boating is considered safe as long as speeds do not create excessive water spray. Fishing is technically permitted, but OHA advises against eating fish caught near bloom areas. Those who choose to eat them should remove fat, skin, and organs, rinse fillets with clean water, and cook thoroughly.

People should not drink lake water directly and should note that boiling, filtering, or using camping-style filters does not remove cyanotoxins. Contact campground management or the Jefferson County Health Department for information about water at specific campgrounds.

When Will the Advisory Lift?

OHA monitors bloom conditions and lifts advisories once toxin levels return below safe thresholds. No timeline has been given for Lake Billy Chinook. Visitors planning a Fourth of July trip to the reservoir should check OHA’s Harmful Algae Blooms website (oregon.gov/OHA) for the most current status before heading out.

To report an illness or get health information, contact OHA at 971-673-0482.