(Editor's note: This is Part 3 in a 3-part series on the Bay Area watershed. In Part 1, we examined a radical new daylighting proposal in Berkeley ; and in Part 2, we looked at the changes that SF streets may face under a bold plan by the Public Utilities Commission .)
Early daylighting projects like the Napa River, Strawberry Creek, and Codornices Creek formed the basis for a worldwide shift in the possibilities presented by urban watersheds. Now, a series of best-practices has begun to emerge from the ever-growing number of daylighted streams around the world, which could inform the proposed transformations of creeks here in San Francisco.
The SF Public Utilities Commission is now studying the feasibility of daylighting Yosemite Creek, Islais Creek, and Stanley Creek. While their research is underway, Streetsblog decided to take a closer look at successful urban water projects around the world from which planners might draw inspiration.
At one time, the standard treatment was to place streams into culverts underground; now, aquatic restoration is viewed as a top priority. The EPA's "Principles for the Ecological Restoration of Aquatic Resources " describes federal priorities for restoring wetlands. The EPA calls for an increase in wetland area of of 100,000 acres per year, and provides municipalities with 17 guidelines, including "Address ongoing causes of degradation," "Design for self-sufficiency," "Use natural fixes," and "Focus on feasibility."
On a local level, some cities have made a similar effort to document the correct treatment of wetlands. The Seattle Public Utilities Commission provides citizens with a handbook for caring for natural drainage systems , making it easy for property owners to manage the Natural Drainage Systems near their homes.
"The science is pretty well-established at this point," said Mark Frey, a biologist working for the Presidio. Streetsblog spoke to him this week about the park's high-profile efforts to restore areas such as El Polin Spring, Thompson Reach, and the lesser-known Dragonfly Creek. As biologists continue to monitor and study urban waterways, there's a growing confidence in our ability to manage those projects.
Turning Sewers into Show-Stoppers
Some daylighting projects encounter success beyond what their designers could have hoped for.
Cheonggyechun in South Korea is the latest to dazzle observers . A prominent city feature for hundreds of years, it had become an open sewer by the mid-20th century and was buried. But this decade, a $384 million project cleaned the river, removed vehicular traffic, and established habitats along its shores. The revitalized waterway has become a destination not only for humans (90,000 visitors per day), but for fish species (which increased from 4 to 25), bird species (from 6 to 36), and insect species (from 15 to 192).
Elsewhere in the park, the grasslands above El Polin Loop are being cleaned and replanted. A tributary that currently "short-circuits" the land in a plastic pipe will eventually flow freely through the trees. Dragonfly Creek, flowing near the Pet Cemetery beneath Doyle Drive, will see extensive rehabilitation as part of Caltrans' reconstruction of the highway.
The Presidio's location within San Francisco provides a unique opportunity for collaboration. "As an agency, we don't work with the city," the Presidio's Mark Frey told Streetsblog, "But as individuals, we visit the parks," including Glen Canyon Park and the wetland work at Lake Merced. When it came time to re-plant the native Islay Cherry in the Presidio, biologists ventured over to Bayview Hill to harvest seeds .
A decade of planning, fundraising, and construction  began in the 1980s. By the time it was completed in 1996 , the area was unrecognizable : railroad tracks and automobile thoroughfares were gone, replaced by a massive riverwalk . Now, rather than parking lots, the area features gondola rides  and a late-night bonfire art installation on the river  that has drawn millions.
Riverwalks have proven to be popular amenities in cities across the country, although few have required a daylighting project as extensive as Providence's. The Reno Riverwalk features kayaking  on the Truckee River, and hosts an annual festival . In San Antonio, a $384.5 million project will revitalize 13 miles of river. And 1,900 feet of the Sawmill River in Yonkers, buried for 100 years, could be daylighted soon  as part of the city's $1.5 billion revitalization project.
Blending in to the Landscape
Elsewhere, urban creek projects have sought a lower profile. They don't have to be the landscaping centerpiece of a city to make an important contribution.
Los Angeles has the lowest per-capita park space of any US city  -- only 4% of the land is park. (San Francisco is more than twice that, at 9%.) In the middle of the city, plans are underway to restore Compton Creek , turning it from a polluted flood-control channel into a natural habitat. Despite several setbacks, watershed research continues .
Seattle has also caught the daylighting bug, with several significant projects. Over six hundred feet  of Ravenna Creek were daylighted in 1996 at a cost of under $2 million, restoring land  that had been filled in during highway construction.
A decade later, Seattle's Madrona Creek was revitalized for $805,000  with bridges, ponds, cascades, and weirs , as well as human amenities like observation decks and trails . It's since become a habitat  for the endangered chinook salmon.
Seattle's Thornton Creek was perhaps the most difficult undertaking, requiring that environmentalists take the city to court. Seattle had initially claimed that the creek simply didn't exist; but in 2004, the city reversed course, with a plan to restore the creek . Credit for the Thorton Creek daylighting goes to persistent neighbors who fought for years on the water's behalf; one community leader recalls gatherings at which cardboard models of the proposed landscaping was built on a kitchen table, with children fabricating trees for the makeshift diorama.
At the time, the site was a paved-over lot, slated to become a shopping mall and parking garage . Thanks to activists  -- and $6.85 million in funding -- it is now a transit-oriented mixed-use development , featuring a bioswale  capable of treating stormwater through natural processes before releasing it downstream.
A Model for San Francisco
Forty creeks have been daylighted around the city, amounting to over 12 miles of waterways  in a city with challenging, dense development similar to that of San Francisco. Innovative "compromise" approaches have allowed the city to accommodate ecological concerns without requiring difficult -- if not impossible -- land acquisition. On the Nedelbach, for example, space constraints were addressed by building tall, straight walls along the water, suitable for use as benches. It's not quite a natural shape, but it's close enough that the stream is now a trout habitat.
Elsewhere in the city, the Wolfgrimbach incorporates runoff from local homes and the Frisenbergbach is used by residents for swimming. Since daylighting began in 1988, streams have been incorporated into children's playgrounds, along city streets, and though residential developments.
Although Zurich provides inspiration for San Francisco's future, it's far from the only source. From Napa to South Korea to Providence, imaginative new ideas have turned urban creeks from an unhygienic nuisance into a critical component of cities' watershed and of sustainable development. All that's required to imagine similar transformations here in SF is a willingness to acknowledge a landscape that predates our arrival -- a landscape that has owned the hills and valleys of our city for thousands of years.