Recently, the city of Seattle announced a goal to dramatically increase the amount of water treated by rain gardens, green roofs, green streets, permeable pavement and other alternatives that seek to treat stormwater more naturally instead of carry it away in pipes.

Right now, as the graphic below shows, the city estimates it’s managing somewhere north of 100 million gallons of polluted runoff with “green stormwater infrastructure,” which helps control flash flooding and helps filter out pollution that might otherwise wind up in Puget Sound. Mayor Mike McGinn and some city council members want to ramp that number up to 700 million gallons by 2025.

The city has a road map to get about half of the way there by incorporating green stormwater techniques into streets and other public spaces, providing utility rebates for homeowners who handle rain from their roofs and gutters with cisterns or gardens, updating codes and partnering with developers, or helping neighborhoods incorporate stormwater swales into traffic calming projects or other amenities. But the bulk of the gains will have to come from projects and approaches that city staff will spend a little more than a year identifying.

Seattle green stormwater goals chart

Source: City of Seattle’s Office of Sustainability (Click on graphic to enlarge.)

To its credit, Seattle pioneered one of the first pilot projects in the nation to incorporate natural techniques that absorb rain, control flooding, and remove pollution into public streetscapes. But in the last few years, other cities have picked up the ball and run with it.

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  • Portland, for instance, is well into its $55 million “Gray to Green” initiative to manage stormwater more sustainably and restore native vegetation. Officials estimate they’re now treating 77 million gallons of polluted runoff with green street projects, 9.5 million gallons with green roofs, and 1.2 billion gallons by convincing homeowners to disconnect their gutters and downspouts from the city’s combined sewer system.

    As Mayor Mike McGinn says in the video below (which provides more detail about Seattle’s green stormwater goals and previous projects), Seattle has some catching up to do:

    I hate to say it, but there are a few other cities that might be a little ahead of us on the wide-scale implementation, and we don’t like to be second in anything when it comes to the environment. So that’s why we’re setting this goal. We’ll see how we’re doing—we may have to up the ante down the road if we want to be number one.

    Other cities have reached even more ambitious agreements with federal regulators to meet obligations to control combined sewer overflows (CSOs) with green stormwater techniques. Those overflows happen when stormwater from heavy rains overwhelms a city’s public plumbing and sends sewage and other pollutants directly into streams, lakes, oceans or bodies of water. Under the Clean Water Act, that pollution must be curtailed.

    The sheer amount and nature of CSO work to be done in older Eastern cities versus Seattle necessarily yields an apples-to-oranges comparison. But Seattle and King County remain officially on the hook for more than $1 billion worth of upgrades to prevent the last small sewage overflows from happening, as part of a legally binding agreement with federal regulators. Critics, however, have rightfully asked whether that money could be better spent tackling more important water quality problems.

    Fortunately, the city of Seattle lobbied for flexibility in its latest CSO agreement to build some green stormwater projects that provide a range of benefits ahead of other infrastructure aimed purely at reducing sewage overflows — projects that may ultimately prove to be more expensive and less valuable to improving the overall health of Puget Sound. Right now, the city is still obligated to finish those CSO projects, which include hundreds of milllions of dollars in “gray” infrastructure such as pipes and underground storage tanks. But if the city can prove that green stormwater investments or simple fixes like sweeping streets to remove pollutants can accomplish the job for less money, perhaps there might be room to re-negotiate its CSO commitments down the road. As Mayor McGinn put it:

    Our agreement commits us to a fair bit of gray infrastructure, which is what the feds have traditionally preferred. But we worked for and got the flexibility to prove to them that green infrastructure could replace gray infrastructure. So as we move forward, we may be able to put more of that investment into these types of streetscape improvements as a way of meeting that objective.

    Seattle’s new green stormwater goals don’t, unfortunately, come with new funding. (Seattle Public Utilities has already dedicated between $20 and $35 million for green stormwater capital improvements over the next four years). It does require people from all the different departments that have a hand in managing polluted runoff to come to the table. City and county stormwater officials around Puget Sound have repeatedly said that a lack of coordination between departments hinders their efforts to expand the use of green stormwater solutions. But by making green infrastructure a priority, a transportation department, for example, will be more inclined to incorporate it when doing road construction, or the parks department might include a green roof or rain garden when designing park improvements.

    Better coordination should allow Seattle to take advantage of cost-effective green projects wherever and whenever they arise, and shift this technology from an eco-novelty to a more standard way of doing business. And in large city bureaucracies, sometimes the simple act of setting a numerical goal and making departments accountable has a way of focusing attention and getting things done, as Seattle Public Utilities director Ray Hoffman explained:

    Quite frankly what gets measured, gets managed. There’s truth to that. Where the city sets goals, it tends to deploy resources to meet those goals. We learn as we go along…and every project we do, whether with SDOT or residents, we learn a little bit more. We want to get to the point where this  sort of becomes a conveyor belt system for us and we can do natural drainage just as quick and easy as some of the other projects we’re involved with day to day.