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Completed GSI Projects

Past projects using green stormwater infrastructure were called “natural drainage” projects and were focused in creek basins as a way to protect those waterways from the damaging effects of stormwater. Most of these areas do not have a piped drainage system so the projects were designed to slow and filter the stormwater flowing across the surface. These projects reduced negative impacts to the creeks by 74 to 99 percent.

Directions to Each Site (pdf)
Most project sites are accessible by car, bus, or bicycle.


Seattle’s Natural Drainage Systems Booklet (pdf)
This illustrated booklet, published thanks to an "Innovations in Government" award from the Kennedy School of Government at Harvard University, provides a comprehensive look at Seattle's nationally acclaimed Natural Drainage Systems projects from concept development through the refinement of NDS strategies and their application to various urban settings.

Seattle Natural Drainage Systems Program Presentation (pdf)
Learn about the problems threatening our waterways and how NDS have proved an effective part of the solution.

Cost-Benefit Analysis (pdf)

NDS Plant List (pdf)
Compilation of plants used on NDS projects.

NDS Street Design Guidelines - February 2007 (pdf)

Natural Drainage Systems in Chinese