California
Toxic algae in Ventura County lakes
9 lakes and waterways in Ventura County have harmful algal bloom reports in California's official data.
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.
- Middle Sespe Creek 2026
- Other River 2021
- Potrero Creek 2026
- Rancho Nuevo Creek 2026
- Rock Creek 2022
- Santa Paula Creek 2022
- Santa Paula River 2023
- Sespe Creek 2020
- Ventura Harbor 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.