Green Stormwater Infrastructure (GSI) -Seattle

Stormwater and green infrastructure:

Public utility companies, cities, and neighborhoods continue to deal with stormwater and wastewater management. The goal is to eliminate pollutant discharge in to our protected water ways. “About two-thirds of Seattle is served by a combined or partially-separated sewer system. Completely separated systems serve the other one-third.”[1] This means during a heavy rain, the water you see running in to the drains, is likely combining with sewage at some point, and overflows directly in to the puget sound or ship canal.  Even if stormwater systems are not combined with sewer, the stormwater carries pollutants such as petroleum, tiny metals, cigarette butts, trash, and bacteria and viruses. Here is a pdf addressing the issue in Ballard, where most sewage/stormwater overflow dumps in to salmon bay.

Seattle Public Utilities and the City of Seattle have created plans and programs to mitigate overflow, and effectively manage stormwater. One main solution is to build additional underground temporary storage and/or retrofit and update existing drainage pipe infrastructure. The second main solution is green infrastructure, which has lower upfront construction costs, and by far adds more social and economic value to the communities in which the projects are installed. Green infrastructure (in terms of stormwater management) includes rain gardens for water detention, bio-swales, green roofs, cisterns, porous pavement, de-paving, and planting trees.

Programs and Plans:

700 Million Gallons

This site is in coordination with RainWise Rebates, a program that provides up to $3.50 per square foot of an approved rain garden project at your house or neighborhood. Here is a map of rebate eligible neighborhoods, based on their proximity to combined sewer overflow (CSO) systems.


Here is a map showing data on projects installed in coordination with 700 million gallons.


Things I noted:

1: Most projects are happening in single family neighborhoods

2: Not much action in SODO, industry along the Duwamish, and downtown.

Neighborhood Matching Fund

Through the Seattle Department of Neighborhoods, community groups and non-profits can apply for a matching grant of up to $100,000 for a project that increases civic engagement and benefits the community or neighborhood in clear ways.

The Beacon Food Forest Phase 2 project was recently awarded $99,960, nearly matching their fundraised amount of $110,450.  The Beacon Food Forest is located in Jefferson Park, and provides a large community P-patch with equipment, an outdoor kitchen, and other amenities. This match has been significant for the Beacon Food Forest, and there is potential for neighborhood green infrastructure projects to be matched as well.

Neighborhood Park and Street Funds

Also through the Seattle Department of Neighborhoods, SDOT provided nearly 2 million dollars for street improvement projects. Here is a link to a pdf showing the project descriptions.

The cost of these projects are a little mind boggling to me ($90,000 for Curb bulbs at McGilvra Blvd E & E Madison St & E Garfield St), but they state that Seattle residents democratically decide where to spend the funds. There is potential here for budgets to increase, and GSI projects to be installed.


For individual homeowners and community/neighborhood organizers, there are subsidy and rebate programs available. For builders and developers, there are no programs I could find endorsed by the City of Seattle, only encouragement. Slowly the smaller residential and neighborhood projects will add up and achieve scale. But I think city governments need to invest substantially more dollars to allow for developers to plan these projects in our downtown and industrial zones. For one, these areas combined contribute more pollutants and two, can achieve the scale to transform a city’s effectiveness in managing wastewater and stormwater, by investing and saving significant dollars in the long run.

This is a pdf prepared by the city of Seattle in which they are working with the firm CMG landscape architecture, to develop and build a comprehensive street scape plan for an area of South Lake Union.

CMG Landscape Architects operate out of San Francisco. There portfolio includes the Treasure Island Master Plan project which is the largest plan ever to achieve LEED-ND platinum certification. Globally it is 1 of 17 LEED-ND platinum projects.


Here is a list of websites that show the City of Philadelphia as a precedent for GSI investment:






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