California
Toxic algae in Mendocino County lakes
17 lakes and waterways in Mendocino County have harmful algal bloom reports in California's official data. The most recent entry is for Eel River: There are no bloom reports for Eel River in the last 30 days of California's data. The most recent was a bloom report on 3 August 2026 at Potter Valley Tribe Van Arsdale Reservoir. Eel River, Lake Mendocino and East Fork Russian River and 1 more have 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 River Hydrologic Area 2021
- Cahto Creek 2024
- Lake Emily 2026
- Lily Pond 2022
- Little River 2023
- Long Valley Creek 2026
- Mill Creek 2021
- Mill Creek Hydrologic Subarea 2022
- North Fork Eel River Hydrologic Area 2021
- Pudding Creek 2022
- Trout Creek 2022
- Upper Mill Creek 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.