California
Toxic algae in Butte County lakes
12 lakes and waterways in Butte County have harmful algal bloom reports in California's official data. The most recent entry is for Lake Oroville: There are no bloom reports for Lake Oroville in the last 30 days of California's data. The most recent was a bloom report on 9 September 2026 at middle fork upstream of Bean Creek. Lake Oroville has had blooms in three or more years.
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.
- Big Chico Creek 2024
- California Park Lake 2016
- Clear Creek 2021
- Concow Creek 2021
- Dry Creek 2021
- Feather River 2026
- Fish Creek 2026
- Phantom Falls Creek 2023
- Private Pond 2025
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.