Oregon
Oregon algae bloom map
30 Oregon lakes with a bloom history, coloured by the latest entry in the state's published data (to 23 December 2025). 17 lakes show a bloom or advisory in that latest entry.
Lakes with a bloom in their latest entry
Newest first. For this season's conditions, use the OHA current advisories page.
- Upper Klamath Lake Health advisory
- Gerber Reservoir Precaution
- Thief Valley Reservoir Health advisory
- Brownlee Reservoir Health advisory
- Tenmile Lakes Precaution
- Wapato Marsh Health advisory
- Hells Canyon Reservoir Health advisory
- Devils Lake Precaution
- Eckman Lake Health advisory
- Willamette River Precaution
- Haystack Reservoir Precaution
- Cullaby Lake Precaution
- Odell Lake Health advisory
- Lost Creek Lake Health advisory
- South Umpqua River Permanent advisory
- Lake Billy Chinook Health advisory
- Fern Ridge Reservoir Health advisory
How to read this map
Each dot is a lake or river with enough reports for its own page, placed at the centre of its reports. The colour shows the latest entry in Oregon's official data, and bigger dots have had blooms in more years. Oregon publishes its data in yearly files, so colours reflect the last published season.
Lakes without a dot may never have been tested. No report doesn't mean the water is safe. For official live conditions, see the OHA current advisories page, and browse every county on the Oregon page.