Explore the Bay Area Monitor
On the Path to Balanced Watershed Use
By Robin Meadows
Ever since he was a little boy growing up in San Francisco, Andy Howse has wanted to hike in the hills that beckon just west of I-280 between San Bruno and Woodside. “I asked my dad why we couldn’t go there and he said it was to protect our water,” he recalled. Called the Peninsula Watershed, the 23,000 acres are owned by the San Francisco Public Utilities Commission (SFPUC) and provide part of the city’s drinking water.
Nationwide, most water agency-owned watersheds — areas that drain into a creek, lake, or reservoir — are off limits to the public. But “in the Bay Area, some water agency watersheds are open to the public, and New York City does this too,” said Tim Ramirez, who manages natural resources at the SFPUC. “The rest think we’re crazy.” The biggest risk is that people will spread pathogens, including intestinal parasites such as giardia and cryptosporidium. Another downside is that trails can erode, muddying water and filling reservoirs with sediment.
Today, the Peninsula Watershed hills are more accessible than when Howse was a child — but only a bit. Ridge hikes require a docent and are limited to 60 people a day, three days a week. Now a father himself, Howse hopes his infant daughter will someday be able to hike there freely. “There should be public access to nature,” he said. “We need to teach our kids to be stewards of the land.” So he founded Open the SF Watershed to advocate for opening the Peninsula Watershed to hikers and bicyclists, envisioning a trail system that connects it with the many parks along its edges. And he’s about to get part of his wish.
Allowing more people on watersheds that supply drinking water can work. The Marin Municipal Water District (MMWD) gets most of its water from Mount Tamalpais, which is a state park. “We get 1.8 million visitors a year,” said Mike Swezy, who manages MMWD’s 22,000 acres of watersheds. “Hordes of people are eager to enjoy nature.”
But all those people come at a cost. Take the Cataract Trail, one of the most popular on Mt. Tam for its series of waterfalls. “It’s stunningly beautiful in the winter and there can be 400 people per hour,” Swezy said. “It’s getting loved to death.” People trample plants at waterfall overlooks and may have driven the endangered yellow-legged frog from Cataract Creek. “They’re no longer there, probably because their egg masses were disturbed,” he explained.
And after a good rain, trails are wet and fragile, crumbling easily along the edges and eroding. Worse, some hikers and mountain bikers go off trail. “Most are law-abiding, but a small group wants their own wilderness experience and will actually construct their own trails,” Swezy said. “Where people have access, you have unauthorized use.”
Trails that are not built properly are more likely to erode, and cutting new trails harms nature by letting weeds take root and spread, degrading habitat for wildlife. “We don’t have the resources to restore it all,” Swezy said, adding that Mt. Tam is home to at-risk species like the northern spotted owl and is a “hotbed” of rare plants.
The Bay Area is rich in native plants and animals, making it one of 25 biodiversity hotspots worldwide. Water agencies own about a fifth of Bay Area open space and “nearly 90 percent is essential to biodiversity,” the SFPUC’s Ramirez said.
The Peninsula Watershed that Howse wants to open up is particularly rich in native species, from wildflowers and bunch grasses to eagles and mountain lions. “It’s relatively untouched,” said Arthur Feinstein of the Sierra Club’s San Francisco Bay Chapter. “It has the highest density of listed species of any watershed around.” These at-risk species include the San Mateo woolly sunflower and the chocolate lily, which grows only in the Peninsula Watershed, as well as several butterflies, the San Francisco garter snake, and marbled murrelets — black-and-white seabirds that nest in the watershed’s old-growth Douglas fir trees.
Rather than allowing “uncontrolled” access to the Peninsula Watershed, the local Sierra Club and other environmental groups favor expanding the docent program. “When there are more people, wildlife diminishes,” Feinstein said.
SFPUC is heading towards something in between what Howse and Feinstein want. “We have 11 to 12 miles of trails in the works that make connections with neighbors around us,” Ramirez said, adding that the new trails will be on the perimeter of the watershed. “There’s less risk when they’re farther from the reservoirs.” The planned trails, which he expects will open to the public by 2018, will bring the Peninsula Watershed’s total to more than 30 miles and will fill a six-mile gap in the Bay Area Ridge Trail.
But access to the watershed will still be restricted. For example, SFPUC may adopt an annual permit system like the East Bay Municipal Utility District, which has 80 miles of trails near its Lafayette and San Pablo reservoirs. “You can track use and it’s an educational opportunity — people have to learn about hiking on a watershed,” Ramirez noted.
Keeping people from going off trail will be among the biggest challenges. Options include volunteer patrols and fencing in key areas. As MMWD’s Swezy said, “People are hungry for nature and you want to satisfy that — but we do need wild places where human impact is minimal, even in urban areas.”
Robin Meadows covers water for the Monitor.