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Rain Gardens and Cisterns and Swales, Oh My!

Hundreds of millions of gallons of polluted water from rain storms (“stormwater”) flow into Seattle’s creeks, lakes, and Puget Sound every year – runoff that contains bacteria from sewage overflows and toxins like petro-chemicals, pesticides, and heavy metals from our yards and cars. “Green stormwater infrastructure” (GSI) helps prevent this pollution by slowing the runoff and using natural systems to filter and clean the water close to where it falls as rain.

Picture of roadside raingarden

Roadside raingarden

GSI methods include bioretention swales, rain gardens, cisterns that collect stormwater and store it until it can be released slowly, pervious pavement (instead of traditional cement which water runs off of instead of through), and green roofs. Seattle has been a national leader in the development and application of these technologies for over a decade, and these approaches are now considered best management practices by the U.S. Environmental Protection Agency and Washington State Department of Ecology.

But there’s more we can do to increase the use of GSI technologies and protect our waterways. The Mayor recently announced a goal to achieve 1,000 “greened gallons” (stormwater managed with green infrastructure) annually per resident by 2025. This represents about a six-fold increase over the amount of stormwater Seattle currently manages with green infrastructure. To help achieve this goal, the Mayor signed an Executive Order (PDF) that directs City departments to develop a coordinated approach to significantly increase the use of natural drainage systems and Council will adopt a resolution supporting the goal in April.

What can you do? There’s plenty!

  • Explore stormwater solutions tailored to your property with Residential Rainwise (some areas qualify for rebates to install cisterns)
  • Practice green gardening to reduce pollutants at their source
  • Maintain your car to prevent oil leaks onto streets – no leaks means less polluted runoff
  • Check out this PBS News Hour story about stormwater’s impacts on Puget Sound and how scientists are learning more about the benefits of green stormwater infrastructure.