California’s five-year drought is changing our take on rainfall in cities, recasting it from a threat to a resource. “For so long, stormwater was simply a nuisance,” said Keith Lichten of the San Francisco Bay Regional Water Quality Control Board. “We needed to get it out of the way as quickly as possible to protect structures.” But stormwater can also be an asset. Instead of directing it into gutters and straight down stormdrains, we can capture and clean it in rain gardens and other planted areas.

This green infrastructure mimics the natural water cycle, replenishing groundwater while enhancing our communities and ecosystems. “Green infrastructure is important to the quality of life in the Bay Area, not just to the water supply,” Lichten said.

A trio of recent laws will nudge us closer to making this vision a reality. The latest, Assembly Bill 2594 (Gordon), confirms that whoever captures stormwater also has the right to use it, while 2014’s Assembly Bill 2403 (Rendon) lets water agencies collect money for stormwater capture. And 2014’s Senate Bill 985 (Pavley) established a key funding eligibility requirement for that year’s Proposition 1; to receive stormwater project grants from the voter-approved water bond, jurisdictions must develop stormwater resource plans. These plans are underway in the Bay Area, with the final versions due in 2019. “We want cities to figure out what they need to do, and where they need to do it, to shift stormwater from gray to green,” Lichten said.

Stormwater could be a significant addition to California’s water supply. While the potential is still unknown in the Bay Area, Los Angeles estimates that rainfall could provide nearly half a million acre-feet per year, said Steven Moore, a member of the State Water Resources Control Board. This may sound trivial compared to the 33 million acre-feet people use statewide each year, but it’s not. “Stormwater could make a difference,” Moore said. “It could see us through seven years of drought instead of five.”

Ways of capturing stormwater include low impact development, which minimizes hardscaping in favor of permeable surfaces. These let runoff percolate into the soil and recharge groundwater, essentially storing rain from wet years for use during dry ones. Another approach is bioswales, planted areas along curbs that are engineered to collect rainwater that sheets off sidewalks and streets. Besides boosting the water supply, permeable surfaces and bioswales help filter out the oil, pesticides, and other pollutants that rain picks up from the moment it hits a hard surface. “Green infrastructure provides a double-sided benefit, improving water quality and supply,” said Newsha Ajami, director of urban water policy at Stanford University’s Water in the West program.

A third benefit is that green infrastructure slows the stormwater that flows into stormdrains. In conventional gutters and stormdrains, stormwater builds up speed and “packs an erosive punch of energy into creeks,” Lichten said. In contrast, slowing stormwater helps protect our waterways, renewing creeks and wetlands.

Moreover, rain gardens and bioswales are assets to urban communities. “You can see the benefit with your own eyes every day as you walk down the street,” Moore said, citing green areas that provide hummingbird and butterfly habitat in the middle of cities.

The Bay Area already has a bit of green infrastructure. San Francisco has eight demonstration projects underway, including rain gardens — which are like bioswales but are less precisely engineered — and partial daylighting of Yosemite Creek to manage runoff from McLaren Park. In the East Bay, examples include the El Cerrito Green Streets Pilot Project, which retrofitted 750 feet of San Pablo Avenue with rain gardens, as well as the San Pablo Avenue Green Stormwater Spine, which retrofitted a 12.5-mile stretch with a variety of green infrastructure.

But given that the technology is so well established, not to mention so beneficial, why isn’t green infrastructure more widespread? The main reason is that funding is scarce. “One of the biggest challenges of changing our approach to stormwater is the cost,” said Water in the West’s Ajami.

Proposition 84 — the 2006 water bond — provides some funding for green infrastructure, including half of a new $3.4 million initiative called Urban Greening Bay Area; the other half is from the Environmental Protection Agency. The initiative will include the Chynoweth Avenue Green Street Project in San Jose, which will install rain gardens and tree-planted medians, as well as projects in San Mateo and Sunnyvale.

Additional green infrastructure funding will come from Proposition 1, which allocated $200 million for stormwater projects with multiple benefits. “We want the biggest bang for your buck,” explained Sean Maguire, who manages the state Water Board’s Storm Water Grant Program. So far, the program has allocated $9.5 million for stormwater planning around the state. Three of the 22 projects are in the Bay Area, with planning grants of nearly half a million dollars each going to the Contra Costa County Flood Control and Water Conservation District, the Santa Clara Valley Water District, and the Sonoma County Water Agency.

By the end of this year, the next round of Proposition 1 funding will provide $100 million to build stormwater projects, and a number of Bay Area proposals are in the running. The balance of the bond money will go toward a second round of stormwater implementation projects in 2018.

But the available funding is not nearly enough to meet all of California’s green infrastructure needs. Street-by-street retrofitting will cost an estimated $20 billion in Los Angeles alone, Maguire said, and “statewide the price tag will be astronomical.”

Even California’s existing old-style stormwater systems are underfunded. According to the Public Policy Institute of California, the shortfall is $500 million to $800 million per year. Stormwater funding is pinched by Proposition 218, which passed in 1996 and mandates a two-thirds vote for raising local property-related fees. While rates for water utilities and wastewater treatment were exempted from the supermajority requirement, rates for stormwater systems were not. “It’s an unintended consequence — the people who were working on it just didn’t know,” Moore said. “We’re sitting on an impending disaster.”

That said, he also thinks California’s lag in maintaining stormwater infrastructure may have a silver lining: “It gives us the opportunity to do it in an integrated way that incorporates green infrastructure, rather than just rebuilding the system.”

And Lichten thinks this new vision for using stormwater to benefit us may also hold a solution to the funding problem. “There’s lots of transportation funding in the Bay Area and it can support ‘complete streets’, which have bike lanes and walking paths,” he said. “Maybe it can support green streets too.”

Robin Meadows covers water for the Monitor.