Distribution Of Fecal Coliform Bacteria In A Central California Coastal Stream

Pillar Point is a popular recreation area and one of the most contaminated beaches along the central California coast. This study was undertaken to locate the source of fecal contamination at Pillar Point. Identifying the source of fecal contamination in coastal creeks is important for protecting the health of swimmers and the coastal ecosystem. Frenchman’s Creek is the only stream that drains the Coast Ranges into the ocean at Pillar Point. The creek flows from coastal sage scrub, through rural and suburban watersheds, to the ocean. We conducted a systematic survey of water, soil, and vegetation along the 4-km creek from headwaters to estuary. Coliform and Enterococcus bacteria were used as indicators of fecal contamination. Total coliform and fecal coliform bacteria were counted using the multiple-tube method. A membrane-filtration test was used to determine enteroccocal numbers in the samples. Fecal contamination begins approximately 0.8 km upstream from the estuary; heavy contamination was detected at four of the sites investigated. In these sites, total coliforms exceed 2400/100 mL and enterococci exceed 80/100 mL. Fecal coliforms (from mammals) were found at these sites. Coliform counts are being performed on soil and aquatic vegetation to determine whether these are reservoirs for fecal coliform bacteria or the fecal coliforms are from land-based anthropogenic sources.