Health Advisory for Oswego Lake
UPDATE
On Wednesday, October 15, the Oregon Health Authority (OHA) lifted the recreational cyanoHAB advisory for Oswego Lake due to levels of microcystin and saxitoxin dropping to below recreational use value.
However, detected levels of microcystin and saxitoxin are still above OHA’s educational guideline values for dogs. Owners should continue to keep their pets away from the water.
Signs posted at Lower Millennium Plaza Park have been updated.
For more information, please visit the Oregon Health Authority - October 15, 2025.
On Tuesday, September 30, 2025, the Oregon Health Authority (OHA) issued a recreational use advisory for Oswego Lake due to a possible harmful algal bloom (toxic bloom).
- Please avoid swimming, water skiing, and high-speed boating in areas where blooms are present.
- Do not drink lake water or allow children or dogs near the water.
- Avoid eating fish caught from the lake.
Signs have been posted at Lower Millennium Plaza Park entrance.
Symptoms of exposure can include nausea, stomach cramps, diarrhea, and vomiting. Pets may show signs such as weakness, seizures, or loss of appetite.
For more information, please visit the Oregon Health Authority - September 30, 2025.
