Green Stormwater Infrastructure

Managing stormwater with natural drainage.

Green stormwater infrastructure (GSI) is a toolset of best practices for stormwater management that mimic natural processes and includes stormwater cisterns, vegetated roofs, permeable pavement, raingardens and more. Seattle's trees also play a role in managing stormwater runoff, mostly by intercepting and evaporating rainfall before it ever hits the ground. Be sure to check out the Trees & Open Space section to learn more about the benefits trees provide in Seattle. What is green stormwater infrastructure graphic

The Office of Sustainability and Environment works closely with Seattle Public Utilities to coordinate progress toward the City's goal (via a 2013 executive order and City Council Resolution ) of increasing (GSI) implementation to manage 700 million gallons of water annually by 2025.  Roadside GSI is sometimes called "natural drainage systems," and is designed to remove, slow, and clean runoff from our streets to prevent damage to our lakes, creeks and Puget Sound. Roadside GSI can also be designed to calm traffic, beautify the streetscape, and increase tree canopy cover. More frequent heavy rain events due to climate change is one important reason for increasing green stormwater infrastructure. GSI is one way the City is meeting its goals for preventing sewage overflow events in large rain events.  It is also being used to protect the ecological integrity of our major creek systems (Pipers Creek, Thornton Creek, and Longfellow Creek) and urban lakes, such as Lake Union.