Oregon Health Authority (OHA) has expanded a recreational use advisory for Lake Billy Chinook to cover all three arms of the reservoir, following detection of elevated cyanotoxins from a harmful algae bloom throughout the popular Jefferson County lake.

OHA originally issued the advisory in mid-June for a section near the Perry South Campground cove. Updated monitoring data showed toxin levels above recreational use thresholds in additional areas of the lake, prompting the expansion to include all three arms: the Metolius, Deschutes, and Crooked River arms.

What Visitors Should Avoid

OHA is advising all Lake Billy Chinook visitors to:

  • Avoid swimming in or near areas where a bloom is visible — look for blue-green, pea-soup-colored, or foamy water near shorelines
  • Avoid high-speed water activities such as wakeboarding, water skiing, and tubing that could cause ingestion of water droplets
  • Keep children and pets out of the water and away from shoreline scum or discoloration
  • Never drink lake water directly
  • Rinse fish caught in the lake with potable water before eating; do not eat fish organs

General boating, kayaking, and paddleboarding are still permissible if participants avoid contact with the water in affected areas, though extra caution is warranted. The advisory does not require closure of the lake or its facilities.

About Cyanobacteria

Cyanobacteria — commonly called blue-green algae — are naturally occurring microorganisms that thrive in warm, slow-moving water during summer months. When nutrients and temperature align, they can form dense blooms that produce toxins harmful to people, pets, and wildlife. Exposure can cause skin irritation, gastrointestinal illness, liver damage, and, in high-exposure cases, neurological effects. Dogs are particularly vulnerable and have died from drinking bloom-contaminated water.

Blooms at Lake Billy Chinook occur periodically during summer but the current advisory is notable for its extent across the entire reservoir.

Plan Ahead for the Holiday Weekend

With the Fourth of July weekend approaching, OHA and Jefferson County officials are urging visitors to the lake to heed the advisory carefully. Blooms can shift rapidly with wind and temperature changes — an area that looks clear in the morning may develop a visible bloom by afternoon.

The advisory remains in effect until monitoring data confirms toxin levels have dropped below safe thresholds. Updates are posted at oregon.gov/oha. For questions, contact Oregon Health Authority Environmental Public Health at 971-673-0405 or Jefferson County Public Health.