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SF Is a (Green) Sponge for Stormwater. Here's the Ordinance that Made It Possible

Redevelopment areas, like Treasure Island near the Golden Gate Bridge, require open space, an opportunity to plan centralized green infrastructure.
  • Ken Kortkamp

The San Francisco Public Utilities Commission (SFPUC) has a goal to manage one billion gallons of stormwater every year using green infrastructure by 2050. The biggest driver of meeting that goal is the Stormwater Management Ordinance, passed by the Board of Supervisors in 2010. As we celebrate the ordinance’s “sweet 16” birthday, here’s a look back on all the work the Urban Watershed Planning Division has accomplished in administering the ordinance — work the team will continue into the future.

The ordinance requires new infill and redevelopment projects in San Francisco to capture stormwater onsite using green infrastructure. It allows the flexibility for a project to choose the most appropriate green infrastructure that aligns with the project’s programming while still guaranteeing that the required stormwater performance is met. Common approaches include rain gardens and bioretention basins, rainwater cisterns, permeable paving, green roofs, and a simple increase in traditional landscape area.

"Building and maintaining green infrastructure is a San Francisco community effort that is having a significant impact on reducing flooding in our low-lying areas and removing pollution from our bay and ocean," says Shayne Martinsen, Green Infrastructure Specialist.

Green infrastructure creates greener living spaces, like interior courtyards, while managing stormwater.

Over the last 16 years, people have become aware that capturing and managing stormwater is critical to the health of our city by minimizing pollutants that wash into the bay or ocean and by helping to transform new developments into stormwater "sponges" — this helps reduce the rate and volume of stormwater released into our sewer system during large storms.

"Every rain garden and green roof we build helps protect our city from flooding, but the real reward is seeing these spaces become part of the neighborhood fabric. It’s been an honor to work on a program where you can literally see the positive impact on the community's quality of life right outside your window," says Andrew Corrales, Administrative Analyst in Wastewater.

Since its enactment in 2010, the Ordinance has made a huge impact on managing stormwater in San Francisco and has contributed significantly to the city’s sustainability goals:

  • Over 475 projects are actively managing stormwater
  • Collectively these projects manage over 280 million gallons of stormwater annually (enough to fill 424 Olympic-sized swimming pools, a 20-acre footprint)
  • Over 95 million gallons prevented from entering the sewer system annually, instead soaking into the ground or harvested for reuse

"It’s been a tremendous opportunity to work within such a well-established program making actionable changes to the city of San Francisco. I’m looking forward to seeing how the program evolves as we inch closer towards our target of one billion gallons," says Patrick DeLong, Assistant Engineer.

Redevelopment areas require open spaces and parks as part of the development agreement. Some of the savvy developers have chosen to plan centralized green infrastructure into the open space or parks. These spaces have been consciously incorporated into the public realm such that the passersby experience them as lush and natural ecological gardens that evoke a more peaceful retreat from the adjacent urban grid.