Venice Beach is one of the dirtiest in California

Venice Beach in Half Moon Bay was the only beach in San Mateo County to receive an "F" grade from Heal the Bay’s 17th Annual Beach Report Card. It was the only beach in the county to receive any grade other than an "A" in dry weather.  A couple of other beaches received poor wet-weather grades (Pillar Point Harbor "C", Surfer’s Beach "C", and Linda Mar at San Pedro Creek "D". Wet weather grades are usually worse because of run-off.  The County’s beaches generally received "A" grades in all weather.

The County Times reports:

A major reason for the fecal bacteria contamination at Venice Beach is that the relatively small area has become host to as many as 10,000 birds, said Carol Ann Towe, a volunteer with the Surfrider Foundation. She said the birds are attracted by food at a nearby landfill and that her
group of volunteers hopes to work with county officials to limit access to the feeding source.

Fitzgerald Marine Reserve at San Vicente Creek historically has been another problem spot for water contamination in San Mateo County, but years of cleanup dating to 1999 have dramatically reduced the levels of fecal contamination there, Towe said. It earned an "A" grade during the dry season this year.

Heal the Bay says that Venice Beach is probably not the only unsafe beach in the county.

One of San Mateo’s most historically problematic beaches, Pillar Point Harbor at Capistrano Avenue, was not monitored this past year as the county health department determined that not enough visitors used the beach to continue monitoring. Heal the Bay believes that the bad publicity surrounding the poor water quality grades at this infrequently visited beach was also a factor in the decision to stop monitoring.