Several popular swimming spots in West Marin routinely failed the state’s recreational water quality standards last year, according to data compiled by the county’s ocean and bay monitoring program.
The monitoring program, which has seasonally sampled 27 sites in Marin since 2003, tests for the three most common indicators of human illness—E. coli, enterococcus and total coliform levels—and warns the public when the state standards for the indicator organisms are exceeded. Typically, the county requires signage, though in extreme cases it will close a site.
Between last April and October, when weekly testing took place, a number of local beaches had one-time hits, including Stinson Beach. But at three spots, the county had to post nearly continuous advisories against swimming—including at Chicken Ranch Beach, the Green Bridge in Point Reyes Station and the Inkwells in Lagunitas. Those locations have been problematic in the past, but last season was unusually constant.
“This is an indicator analysis, indicating that something is going on out there. The test doesn’t tell us what the problem is: it could be a failed septic system, a boat passing by, birds, sea lions,” said Lorene Jackson, the project manager with county’s environmental health division.
Yet, she added, “It’s different if there are problems on an ongoing basis. If it’s consistent, like at the Green Bridge, we have to look at the watershed. It’s a huge watershed, and [many agencies] have been working on Lagunitas Creek for a long time, on cleaning up septic systems upstream, on best management practices for horses and for cattle.”
Lagunitas Creek is one of three tributaries of Tomales Bay, where efforts from a host of regulatory agencies and conservation groups have strengthened since the Bay Area Regional Water Quality Control Board put the bay on its list of impaired water bodies in 2007.
Like other counties across the state, Marin reports the data from its ocean and bay monitoring program to the state water board’s database; it is ultimately the responsibility of the agency that manages the beach or swimming hole to remedy any chronic issues.
Many of the sites the county samples are managed by multiple agencies, including the National Park Service and California State Parks. County parks department takes the lead for the site under the Green Bridge, Chicken Ranch and the Inkwells, where Lagunitas Creek pools in small holes perfect for swimming.
Ms. Jackson pointed to several county efforts in the valley, including the one to establish a community wastewater system for Woodacre and San Geronimo to address failing septic systems that are leaching into the watershed. Pending the outcome of Measure D on the March ballot—which may affect the use of the former golf course property, where the county has proposed setting up the system—Marin will move forward with an environmental impact report on the wastewater project, Ms. Jackson said.
A restoration effort is underway for Chicken Ranch Beach by the parks department and the Tomales Bay Watershed Council. A channel that funnels water from the Inverness Ridge across private property and the beach—and into the bay—routinely exceeds fecal coliform standards for human contact; last year’s testing was no exception.
In 2015, the county paid for DNA testing that ruled out the presence of coliform at the beach from human waste; coliform bacteria can originate as organisms in soil or vegetation as well as in the intestinal tracts of warm-blooded animals. The source remains unclear; there are no hits higher up in the watershed or obvious culprits in the immediate area. Samples taken from the bay off the beach have been generally clean.
Tom Gaman, the council’s chair, told the Light last week that the group was still collaborating with the county and adjacent homeowners to obtain permits for a restoration of the channel.
Although Ms. Jackson said she considers the three sites to be chronic issues, the county typically scores better than average on water quality every year. Heal the Bay, a nonprofit based in Southern California, analyzes the data and puts out annual report cards. The data from last season won’t be crunched until this June, but the year before showed good ratings.
Ninety-two percent of the beaches the county monitors were given an A for water quality, while the remaining 8 percent received a B; that was above average for Northern California, where 93 percent of beaches had a grade A or B. The five-year average in Marin shows 94 percent of beaches receiving an A.
The grading system is based on the beach’s likelihood of causing human illness; an F means there is a high risk of illness and the water should be avoided for up to three days.
Although Marin does not monitor water quality during the winter months, when fewer people are swimming, Heal the Bay separates out grades for any testing that takes place during wet weather. For the rainy days, Marin’s scores in 2018 dropped slightly from the five year-average: only 75 percent of beaches received an A or B grade, compared to the 89 percent average. That was also below the average for Northern California, where 81 percent had A or B grades during wet days last year.
What is the health risk? Luke Ginger, who runs the beach reporting program, said there have been very few epidemiology studies that document water-borne illnesses caused by recreational exposure. Many such illnesses exhibit the symptoms of a common cold, arrive a day or two after exposure and rarely get reported. Given the relative threat, Mr. Ginger said his organization considered the best route to be education.
“We don’t want to demonize the water, or for people to get into their minds that the water is not safe,” he said. “If they keep hearing about beach closures and things, we worry that eventually they will stop going in the ocean. Keeping them informed is the best strategy.”
He added, “We also know that it’s going to be difficult to keep some people out of the water, namely the surfing community. They go when the surf is good, and they are willing to risk the health effects sometimes. In some ways, it isn’t viable to say the beach is closed.”
This month, the board of supervisors authorized the environmental health department apply for regular funding for the beach monitoring program from the state’s water resources control board: $177,675 through 2022.
The county’s historical water quality data is posted at https://data.marincounty.org/Public-Health/Beach-Water-Quality/88ua-5nh2