The Lure of the Creeks Buried Beneath San Francisco’s Streets

(Editor's note: This is Part 2 in a 3-part series on the Bay Area watershed.)

San Francisco may be getting new waterfront soon, thanks to ambitious projects currently being studied by the city's Public Utilities Commission, including proposals for daylighting, or uncovering, long-buried creeks and streams and creating open-air channels that flow alongside the city's sidewalks and streets.

Top contenders for daylighting include: Islais Creek, originating in Glen Canyon Park and flowing through Bernal Heights to Islais Creek Channel, passing under Third Street just north of Bayview; Yosemite Creek, flowing from McLaren Park in Visitacion Valley through Portola to Bayview and entering the bay near Candlestick Park; and the little-known Stanley Creek, flowing along Brotherhood Way into Lake Merced near the border with Daly City.

Like the Center Street daylighting proposal in Berkeley, these projects wouldn't attempt to replicate a natural habitat, due to the limitations of dense human development. Instead, the PUC proposes a "compromise" approach that would merge the needs of communities with the hydrological benefits of exposed waterways.

And those benefits would be significant. A 2007 study by the PUC found that daylighting Yosemite Creek would reduce strains on the water system; an important finding, since those strains regularly cause raw sewage overflows that exceed federal limits. A three-hour storm -- such as the one seen last weekend -- could drop over 50 million gallons onto the Yosemite watershed, overwhelming pipes that are decades past their expected lifespan.

An Urgent Need for Action

With regular high-profile drainage failures during the rainy season, it's no surprise the PUC is investigating innovative solutions for stormwater management.

"We're modeling the impacts of daylighting right now," says Rosey Jencks with the PUC's Urban Watershed Management Program.

Jencks explained to Streetsblog that in 2007, the PUC held a series of community meetings to identify attractive methods for managing the city's watershed. Attendees were placed into teams and given giant maps of the city's drainage basins, laid out like game boards. The maps were accompanied by game pieces that represented ecologically sound water management techniques, such as eco-roofs, rain gardens, permeable paving, and daylighting.

After participants were asked to distribute the game pieces to manage the city's flow of water, daylighting received top marks, not only for its appeal to community members but for its efficacy. Daylighting Islais Creek, for example, would impact 95.6 acres, resulting in a peak flow reduction of three to nine percent. Daylighting Yosemite Creek would reduce the annual runoff volume by 36 million gallons per year.

But in addition to being one of the most effective methods for reducing strain on the city's sewers, daylighting is also one of the most expensive, at a cost of about $2 million per mile. Daylighting Yosemite Creek is expected to cost around $13 million; Islais Creek would be $45 million.

Islais Creek to Flow Through the Heart of Alemany Farmer's Market

Islais Creek in the Alemany Farmers MarketIslais Creek in the Alemany Farmers Market

Islais Creek originates in Glen Canyon Park, home of important species like the Pacific chorus frog, Islay Cherry (for which the creek is named), and the endangered Mission blue butterfly. Modifications on city property would be relatively uncomplicated: The creek would be moved from an underground culvert north of a baseball field to a channel flowing to the west of the field.

It's when the creek flows beneath city streets that construction becomes more ambitious. One PUC plan could daylight water through the middle of Alemany Farm, across the Alemany housing development, along the median of Alemany Boulevard, and through the Alemany Farmer's Market.

Additional construction in the Alemany Farmer's Market is a possibility: A separate plan proposes $7 million in upgrades that augment the market with eco-roofs, permeable paving, and trees. 

The PUC also proposes to terminate the creek in a manufactured wetland at the western end of Islais Creek Channel. The area is currently an asphalt lot just down the street from the headquarters of Mythbusters, used occasionally to store vehicles.

It would be a complete turnaround for a body of water that was once so polluted that it was known up until the 1950s as "Shit Creek." And more recently, Islais has faced environmental near-catastrophe at the hands of the SFMTA: diesel spills in 1994 and 2005 and a sewage spill in 2003.

Yosemite Creek Would Reclaim Nursery, but Cars Threaten Habitat

The proposed Yosemite Creek channel along Woolsey St
The possibilities posed by Yosemite Creek are even more extensive than those posed by Islais Creek, including the transformation of a dilapidated nursery into a unique city park and the restoration of crucial animal habitats.

Yosemite Creek originates in McLaren park, named for Golden Gate Park superintendent John McLaren. (Have you ever noticed the statue in the park of a diminutive fellow holding a pine cone? That's him.)

Currently, the stream flows underground past the University Mound Nursery, which has been owned by the Garibaldi family since the 1920s. Though the family holds the deed to the property, it has fallen into disuse and decay, and in the last decade, the Recreation and Parks Department has considered purchasing the lot at a cost of around $500,000. 

Yosemite Creek on grounds of University Mound NurseryProposed layout for Yosemite Creek on the grounds of University Mound Nursery

Were the city to buy the land, the PUC could construct a much more authentic meander for the creek, winding it through the new parkland with native plants and appealing landscaping.

But an even more ambitious project lies at the end of the creek: Yosemite Slough, site of an extensive environmental restoration project. As part of the Candlestick Point Recreation Area, work on the Yosemite Slough has established new habitat for fish and birds, created 5,000 feet of trails, revitalized 2.5 acres of public parks, and nurtured thousands of native plants.

Much of the environmental work at Candlestick Point is being overseen by WRA Environmental Consultants as part of the Hunters Point Shipyard redevelopment. WRA has expressed interest in incorporating Yosemite Creek water into the wetlands restoration, so the day may come when Yosemite Creek provides habitat all the way from its origin in McLaren Park to its terminus in the bay.

In recent years, however, threats to the ecology of Yosemite Slough have emerged in the form of auto-centric development. A proposal by Lennar Corporation would remove acreage from the park and bisect the wetlands with a bridge designed to move cars to and from a proposed new stadium on game days. According to The Sierra Club, the $100 million bridge would reduce commute times by less than two minutes, but it would be particularly dangerous to shorebirds. An environmental impact report on the project will be considered by the Planning Commission and Redevelopment Agency later this month.

Creating a Legacy of Healthy Waterways

WRA is also responsible for a restoration project along Misson Creek Channel just to the north. Mission Creek Channel is a relatively recent project featuring wetland landscaping, houseboats, a dog run, and extensive public sports facilities just west of AT&T park.

The channel marks the end of Mission Creek, a body of water that can still be glimpsed in basements scattered across the city, including underneath a hatch at Mission High School.

During a recent visit to the park alongside Mission Creek Channel, Streetsblog chatted about the area's restoration with security guard Isidro Villanueva. "Especially when there's good weather," he said, "there's people walking dogs, picnics, kayaking." It's one of those hidden San Francisco spots that you'd never find unless you were looking for it.

The Presidio has seen its share of creek restoration as well. An array of projects are underway to restore habitat and provide human amenities. Thompson's Reach, down the street from Lucasfilm, has been turned from a landfill into a lush valley. A historic brick bridge has been restored, a boardwalk has been constructed and grasslands beneath Inspiration Point, home to endangered species, have been replanted. Newer buildings at the eastern end of the park provide habitat for innumerable mice and work continues on the removal of harmful debris near El Polin Spring. Further west, Lobos Creek provides the bulk of the Presidio's potable water supply.

Only a Hint of a Larger Watershed

These stretches of creek are just a fraction of San Francisco's underground waterways, and only hint at the shape of a watershed that's been routed into hidden channels for decades.

Years ago, when San Francisco was called Yerba Buena, a lake covered parts of the Mission. Washerwoman's Lagoon flowed through the Marina. The Sans Souci Creek traced a path now known to bicyclists as The Wiggle. Hayes River flowed beneath City Hall, delaying an election in the 1980s by flooding the Registrar's Office. Arroyo de los Dolores ran down to 18th street past Dolores Park. Mission Creek flowed to the bay, and is now only visible in brief glimpses such as a pool in the basement of the Armory.

"Today's watersheds are more like sewersheds," argued Christopher Richards, aquatic biologist at the Oakland Museum of California, at a recent SPUR presentation on the city's water.

How intriguing would San Francisco's topography be if the city daylighted more of these amenities?

Other cities have caught the daylighting bug, and in the next installment in this series, we'll take a closer look at the restoration of urban waterways around the world. The residents of Providence enjoy gondolas in the heart of their city. The Reno Riverwalk features areas for kayaking. Phelan Creek in Saint Paul features rain gardens. After a long wait, Longdale Park in Georgia has completed a 10-year transformation.

Each of these projects has implications and lessons that could apply to future undertakings here in San Francisco. All that's required is a little imaginative thinking about what lies under our feet -- and whether it deserves a place of greater prominence.