California
Toxic algae in San Luis Obispo County lakes
15 lakes and waterways in San Luis Obispo County have harmful algal bloom reports in California's official data. The most recent entry is for Atascadero Lake: There are no bloom reports for Atascadero Lake in the last 30 days of California's data. The most recent was a bloom report on 2 April 2026 at southern lake. Atascadero Lake, Laguna Lake and Lopez Reservoir 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.
- Meadow Creek 2020
- Pismo Creek 2018
- Salinas River 2023
- San Luis Obispo Creek 2023
- Santa Margarita Lake 2022
- Santa Margarita Reservoir 2021
- Santa Monica Creek 2020
- Whale Rock Reservoir 2021
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.