Oregon
Toxic algae in Clackamas County lakes
4 lakes and waterways in Clackamas County have harmful algal bloom reports in Oregon's official data. The most recent entry is for North Fork Reservoir: Oregon's archive has no advisory for North Fork Reservoir in 2025. The last was a health advisory in 2011.
Lakes with bloom history
Newest report first. Each lake has its own page with the full history and what the results mean.
Other waterbodies with a report
These have one or two reports in a single year, which isn't enough history for a page of their own yet.
- Clackamas Cove 2015
- Oswego Lake 2025
- Timothy Lake 2011
Source: Oregon Health Authority (OHA), official data, checked 24 October 2026. For today's conditions see the OHA current advisories page. No report doesn't mean a lake is safe: most water is only tested occasionally.