SAN RAFAEL — Signs are posted at four popular Marin County swimming holes, warning bathers to stay on dry land because of contaminated water.
Testing by county health officials showed the water has been unfit to swim in since early last month because of high amounts of coliform bacteria.
The signs are posted at Millerton Point in Marshall, Green Bridge in Point Reyes Station, Chicken Ranch Beach in Inverness and Samuel Taylor State Park.
A sample taken June 19 at Chicken Ranch Beach contained twice the allowable level of the bacteria.
The most recent samples were collected Aug. 6. They indicated all four locations still have higher-than-legal bacteria levels.
A high coliform count often indicates fecal contamination.
“We haven’t reached any conclusions as to where the contamination could be coming from,” said Phil Smith, chief of the county’s Environmental Health Services.