Beach Advisories (Postings and Closures) and Beach Water Quality Monitoring

In California there are three types of advisories about beach water conditions: postings, closures, and rain advisories. Postings are the most common type of advisory. Postings are triggered when a water sample fails to meet the CDPH Ocean Water-Contact Sports Standard (California Health and Safety Code Sections 115875-115915).

A beach posting is an advisory to the public that the bacteria levels in the beach water may cause illness, and local health officers are recommending to the public to stay out of the water in areas where the signs are visible. The most common cause of postings is the dry weather discharge of urban runoff from storm drain systems. A beach closure is an advisory to the public that there has been a sewage discharge that is affecting the beach area.

Closures are put in place immediately after a sewage spill is reported that may affect the beach. The closed beach area will be reopened when water samples meet standards. Because closures represent a definite health risk and postings indicate a potential risk, they are tracked separately.

Rain advisories are pre-emptive warnings that people should avoid swimming in ocean waters during a rain event and for three days after rainfall ceases. Rainwater often carries large amounts of bacteria from a variety of sources to the ocean. Rain advisories are issued via county hotlines and county health agency websites.

Local health officers can also take additional actions, such as permanently posting or temporarily restricting the use of a beach based on bacteria exceedance conditions, for example if there are sites where urban runoff discharges to the beach even during the dry season, and historic data shows that the beach water near the discharge point consistently contains elevated bacteria levels. The Water Board displays the closure and posting data submitted from the County Health Officers on its web site monthly at waterboards.ca.gov/water_issues/programs/beaches/search_beach_advisory.html.

Data visualizations are also available on California's Water Quality Monitoring Council Safe to Swim site here mywaterquality.ca.gov/safe-to-swim/safe-to-swim-maps.html.