Seattle Mayor aiming high on green infrastructure for stormwater

Mar 6, 2013

When you look around the streets of Seattle, you can expect to see less concrete and more greenery being put in over the next 12 years.

The City is planning to dramatically increase its use of green infrastructure to treat stormwater runoff.

Stormwater runoff is acknowledged as the single largest source of pollution in Puget Sound.

Seattle has pioneered the use of green infrastructure – things like rain gardens and green roofs – to catch the rain as it runs off, slow it down and filter it naturally, much as a forest ecosystem would. But so far, these innovations aren’t widely used.

So now the city has set an ambitious goal: treating 1,000 gallons of stormwater per resident with green infrastructure by the year 2025. To visualize that, they said what's needed is about six square feet of raingardens, per person.

The goal is outlined in an Executive Order from Seattle Mayor Mike McGinn. The City Council is to consider the goal in a resolution later this month.

Jill Simmons directs Seattle’s office of Sustainability and Environment. She says this will mean diverting six times as much stormwater into green infrastructure, by installing more cisterns, bioswales, rain gardens and green roofs all over the city.

“The big challenge will now be looking at how do we get from where we are today to 2025 and a six-fold increase is not insignificant, but I think we’re poised at this point to move from, as the mayor said, piloting a lot of stuff, to going to scale,”   Simmons said.

She says they know how they can accomplish about half of this. City code requires new developments to put in natural drainage systems. And each time the city improves an intersection or sidewalk, they can chip away at the goal. There’s also money to incentivize residents to install green infrastructure on private property.

But about half the implementation is yet to be determined.