The Oregon Health Authority (OHA) has issued a recreational use health advisory for Lake Billy Chinook due to the presence of a cyanobacteria bloom — commonly known as a harmful algae bloom — in the reservoir just west of Madras.

The advisory, issued June 15, asks the public to avoid swimming and high-speed water activities such as water skiing and power boating in affected areas of the lake. Authorities warn that activities creating water spray pose a particular risk, as spray can contain cyanotoxins that may be inhaled.

What the Risks Are

Cyanobacteria blooms produce toxins that can cause a range of health effects in humans, pets, and livestock. The primary exposure route is ingestion of water, though the health authority notes that toxins are not absorbed through the skin. People with skin sensitivities may experience a puffy red rash from contact.

Children and pets face elevated risk due to their smaller size and higher activity levels. Dogs are especially vulnerable — they can become severely ill and die within minutes to hours of exposure by drinking the water, licking their fur, or consuming dried crust along the shoreline. Pet owners are strongly advised to keep animals away from the lake during the advisory.

What You Can Still Do

The OHA emphasized that most activities at Lake Billy Chinook remain safe:

  • Fishing is allowed
  • Camping, hiking, and picnicking are safe
  • Low-speed boating is permitted, as long as speeds do not create excessive spray

The lake, formed by the confluence of the Metolius, Deschutes, and Crooked rivers behind Round Butte Dam, is one of Jefferson County's most popular outdoor recreation destinations and draws visitors from across Central Oregon each summer.

What to Do If Exposed

If you or your pet come into contact with water in an area with an algae bloom, rinse off with clean water. If symptoms develop — including nausea, vomiting, skin rash, or eye irritation — contact a doctor or veterinarian. Report any suspected illness from algae exposure to the Oregon Health Authority at 971-673-0405.

OHA will continue monitoring conditions and will lift the advisory when toxin levels return to safe levels. Current advisory status can be checked at oregon.gov/oha.