Bacteria was detected in the water supply of the Mount Laguna Recreation Area plumbing system, prompting the county of San Diego to issue an order to boil the water until further notice.
The presence of total coliform bacteria indicates a plumbing problem, since it can come from fecal matter or the soil, according to the Department of Environmental Health.
People should boil the water until the distribution system is disinfected and testing determines the bacteria is no longer present, the DEH said.
The Laguna Mountain Recreation Area is part of the Cleveland National Forest, and includes campgrounds, recreational vehicle parks and picnic areas.