Muir Beach’s water quality has significantly improved over the past eight years, the San Francisco Bay Water Quality Control Board declared last month when it removed the beach from a list of water bodies impaired by bacteria. National Park Service spokespeople say the improvement was likely linked to the recent restoration of Redwood Creek.
“This has been one of the most significant watershed restorations we have ever done,” said Alexandra Picavet, a spokeswoman for Golden Gate National Recreation Area. “It all started 20 years ago when a Ph.D. student was studying where our best effort for restoring wetlands would be and determined Muir Beach was one of the most valuable and impacted wetlands that we had.”
Between 2003 and 2005, the water offshore from the beach’s quiet cove exceeded levels of water quality objectives for total coliform, fecal coliform and enterococcus bacteria—all indicators of how sanitary water is and correlated with the risk of human pathogens like E. coli—in more than a quarter of all tests.
Scientists suspected the creek carried bacteria on its journey from the peaks of Mount Tamalpais. Although no source was ever pinpointed, a number of theories were put forward: faulty septic systems that serve the 150 homes northwest of the beach, porta-potties formerly near the parking lot, waste from horses at a nearby boarding facility or on trails, wildlife defecation or stormwater runoff.
Now, after years of extensive restoration work to Redwood Creek, the waters are nearly pure again. High levels of bacteria were documented in less than 1.7 percent of tests annually, with some of the last eight years having zero excessive levels detected, far below the 10 percent threshold for being delisted.
Since 2009, the National Park Service has invested millions of dollars to reestablish the creek’s natural flow, fragmented and silted in by historical farming and logging. The project created natural vegetation buffers to filter bacteria and limit human and animal access, realigned a section of the coastal trail away from an eroded ravine that drained into the creek, moved the parking lot slightly north, installed permanent restrooms and a pedestrian bridge over sensitive areas, reconnected the floodplain across a wider area and even rerouted the creek away from residential development.
“This large, multi-year project has really benefitted the natural process, keeping high-water events from lasting as long as they have in the past and restoring the natural wildlife in the area,” Ms. Picavet said. “Hopefully it’s made a much nicer experience for people who visit the area, too.”
For some local residents, the improved water quality proved domestic pets splashing in the surf did not contribute to bacterial levels, contradicting evidence cited in G.G.N.R.A.’s controversial Dog Management Plan in development.
“The new revelations that the water is in good shape emphasizes the accusations that dogs are causing environmental degradation of the water is completely baseless,” said Laura Pandapas, a Muir Beach resident advocating for off-leash dogs. “I don’t see a beach strewn with dog waste. I hear kids laughing and dogs barking. It’s a harmonious situation.”