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
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
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
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
provide additional data on sources of pollution, testing
methods, and causes of beach posting and closures.