California
Toxic algae in Calaveras County lakes
10 lakes and waterways in Calaveras County have harmful algal bloom reports in California's official data. The most recent entry is for Lake Tulloch: There are no bloom reports for Lake Tulloch in the last 30 days of California's data. The most recent was a Caution advisory on 3 August 2026 at South Shore Boat Launch and Campground.
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.
- Esperanza Creek 2022
- Lake Tullock 2026
- Maxwell Creek 2021
- New Hogan Reservoir 2019
- Other River 2019
- Tulloch Lake 2026
- Tulloch Reservoir 2026
- White Pines Lake 2018
Source: California State Water Resources Control Board, official data, checked 24 October 2026. For today's conditions see the California HABs Portal map. No report doesn't mean a lake is safe: most water is only tested occasionally.