California Beach Water Quality Background Information

One of California's biggest industries is tourism, and beaches are a significant tourist attraction as well as being an integral part of California’s culture and economy. Beaches, or more precisely the ocean waters adjacent to the beach, must be safe for swimming and other recreational use. When certain bacteria are present in sufficient concentrations, they pose a health hazard for swimming. County health officers issue various types of warnings when certain kinds of bacteria are found in the water at levels that exceed standards set by the Department of Health Services (DHS). These indicator bacteria imply the potential presence of microscopic disease-causing organisms originating from human and animal wastes. Not only does beach contamination pose real health risks to beach goers, the negative publicity that comes with postings and closures undermines the tourism industry.

In California there are four types of warnings about beach water conditions: postings, closures, rain advisories, and permanent postings. Postings are the most common type of warning. Postings are triggered when a water sample fails to meet the DHS’ Ocean Water-Contact Sports Standard (California Health and Safety Code Sections 115875-115915). A beach posting is a warning 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 a notice 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, newspapers, and radio.

Permanent postings 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 generally contains elevated bacteria levels.

The Water Board displays the closure and posting data submitted from the County Health Officers on its web site monthly. The Water Board also compiles the information into an annual report. These reports, available on the Water Board’s web site at, provide additional data on sources of pollution, testing methods, and causes of beach posting and closures.

In 1997, AB 411 (Chapter 765, Statutes of 1997) mandated that beaches with storm drains that discharge during dry weather and visited by more than 50,000 people per year be monitored at least weekly from April 1 through October 31 by the local health officer or environmental health agency. Beginning in 1999, DHS regulations implementing AB 411 required that local officials must post beaches that exceed standards set by the DHS with warning signs. Beach suspected of being contaminated with sewage must be immediately closed until bacterial monitoring indicates the waters are safe for human contact. AB 1946 (Chapter 152, Statutes of 2000) requires local health officers to submit to the SWRCB, on or before the 15th day of each month, documentation of all beach postings and closures.