Each week San Mateo County Environmental Health Services samples natural recreational waters around the county for concentrations of indicator bacteria. If concentrations of indicator bacteria exceed State or County standards, the area is posted to warn users that they may become ill if they engage in water contact activities in the posted area.

Visit the SMC Health System website to sign up for email notifications of water warnings or to apprise yourself of current warnings, or visit their interactive beach map to prepare for your visit to San Mateo County Parks.