California
Toxic algae in Los Angeles County lakes
34 lakes and waterways in Los Angeles County have harmful algal bloom reports in California's official data. The most recent entry is for Pyramid Lake: There are no bloom reports for Pyramid Lake in the last 30 days of California's data. The most recent was a bloom report on 29 August 2026 at spanish point. Pyramid Lake, Machado Lake and Puddingstone Reservoir and 2 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.
- Pyramid Lake Bloom reported
- East Fork San Gabriel River Bloom reported
- West Fork San Gabriel River Bloom reported
- Santa Fe Reservoir Bloom reported
- Machado Lake Caution
- Puddingstone Reservoir Caution
- Legg Lake Caution
- Castaic Lake Warning
- Castaic Lagoon Bloom reported
- Quail Lake Bloom reported
- Lake Lindero Bloom reported
- El Dorado Lakes Bloom reported
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.
- Apollo Park Lake 2024
- Bull Creek 2020
- Crystal Lake 2018
- Dume Creek 2017
- Earvin Magic Johnson Lake 2026
- Earvin Magic Johnson Park Lake 2026
- Elizabeth Lake 2025
- Horseshoe Lake 2017
- John Anson Ford Park Lake 2026
- La Mirada Lake 2026
- Lake Hughes 2024
- Lake Palmdale 2023
- Lake Piru 2021
- Little Rock Creek 2026
- Los Angeles River 2021
- Malibou Lake 2020
- Malibu Creek 2017
- North Fork San Gabriel River 2026
- Pico Watershed Channel 2025
- Potrero Valley Creek 2021
- Silver Lake Reservoir 2018
- Upper Cattle Canyon 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.