Public Works

The Water Quality Division of San Luis Obispo County monitors for algal growth and harmful algal blooms (HABs) year-round at Lopez Lake, Nacimiento Reservoir, Salinas Reservoir, and Whale Rock Reservoir. Identifying the algal type and cell count supports drinking water treatment facilities with process management and helps detect the presence of algal toxins which pose a health risk to humans and animals. One type of algae that can indicate the potential presence of algal toxins is blue-green algae or cyanobacteria. The California cell count trigger for potential algal toxin producers is 4000 cells/mL. However, the Water Quality Division begins algal toxin testing when blue-green algae reach a count of 2000 cells/mL.  If the algal toxin screens are positive, then a second test is implemented for quantitation and immediate public notification.The current algal toxin monitoring of the reservoirs and further information on harmful algal blooms can be found below.