Friday February 20, 2026
California Department of Water Resources —
Appearing like something out of science fiction, harmful algal blooms (HABs) can form thick mats that accumulate on freshwater surfaces throughout California. Most common during the summer, HABs are a nuisance that can smother entire portions of waterways, sucking oxygen from the system as they decompose, while producing toxins which can be dangerous to humans and pets.
DWR is addressing the issue by drawing on its own expertise and that of partner agencies to better understand the drivers and dynamics of HABs. DWR is in the midst of a five-year, $3 million research project by the National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science’s Monitoring and Event Response for Harmful Algal Blooms program, or MERHAB, with the aim of developing a HAB monitoring program for the Bay-Delta estuary.