California
Toxic algae in Sierra County lakes
9 lakes and waterways in Sierra County have harmful algal bloom reports in California's official data. The most recent entry is for Pass Creek: There are no bloom reports for Pass Creek in the last 30 days of California's data. The most recent was a bloom report on 28 July 2026 at near Jackson Meadows (517PSC038).
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.
- Cold Stream Creek 2021
- Lavezzola Creek 2026
- Lincoln Creek 2021
- Little Mud Flat Lake 2021
- Tributary To Pass Creek 2026
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.