Is the lake safe?

California

Toxic algae in Sonoma County lakes

21 lakes and waterways in Sonoma County have harmful algal bloom reports in California's official data. The most recent entry is for Spring Lake: A bloom was reported at Spring Lake on 3 October 2026 at lagoon area east side of lake. Spring Lake, Russian River and Sonoma Creek 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.

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.

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.