Linda Mar Beach's decades-long pollution mystery finally solved by leaky sewer pipes

Linda Mar Beach in Pacifica has faced decades of chronic fecal bacteria pollution, particularly at its southern end. The contamination, often 30 to 40 times above safe levels, has long puzzled officials and residents alike. Now, investigators believe they’ve identified the likely source: ageing and leaky sewer pipes. The problem first gained widespread attention when the San Pedro Creek Watershed Coalition formed in 1988 to study pollution in the area. San Pedro Creek flows directly into Linda Mar Beach, carrying bacteria linked to human waste. For years, the exact cause remained unclear, with theories ranging from wildlife to domestic pets or failing infrastructure.

The Surfrider Foundation has repeatedly listed Linda Mar Beach among the top 10 US beaches for bacterial contamination. Recent investigations point to Orangeburg pipes—a brittle, tar-impregnated material used in mid-20th-century sewer systems—as the primary culprit. These pipes, known for cracking and leaking, were widely installed in both mains and residential laterals. In response, the City of Pacifica is taking action. Crews are replacing miles of deteriorating sewer mains, while homeowners are being offered $2,000 rebates to upgrade their private lateral lines. Officials warn that the risk is highest during the rainy season, when stormwater can overwhelm weakened pipes and flush contaminants into the creek.

Beachgoers are advised to check warning signs before entering the water, particularly near the southern end of Linda Mar Beach. The area north of Taco Bell Cantina remains safer for swimming and recreation. With pipe replacements underway, the city aims to reduce contamination levels and eventually remove the beach from the list of pollution hotspots.