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Project update

September 24, 2018

Share your priorities with us to inform how and where to install green stormwater infrastructure

King County wants to hear from community members about their priorities to inform how and where to install green stormwater infrastructure in north-central Seattle. In this first phase of the project, King County will consider what types of green stormwater infrastructure should be built and general locations for these facilities within the study area. Technical analysis and community input will help shape the number, type, and location of green stormwater infrastructure facilities.

You are invited to attend an Online Open House and survey - Available through Oct.9

To speak with project staff, learn about the project and provide feedback, you are invited to attend the following: 

Drop-in sessions 

  • Monday, Oct. 1 
    5:30 to 7:30 p.m.
    Phinney Neighborhood Association
    6532 Phinney Ave. N.
  • Tuesday, Oct. 2 
    5:30 to 7:30 p.m.
    Green Lake Community Center
    7201 E. Green Lake Dr. N.
  • Wednesday, Oct. 3 
    5:30 to 7:30 p.m.
    University Heights Community Center
    5031 University Way N.E.

Open house 
Saturday, Oct. 6 
Stop by any time from 10 a.m. to 4 p.m.
Fairview Christian School
844 N.E. 78th St.

Locations are accessible. Please let us know if you need special accommodation.

The County plans to return to the community with a selected alternative in early 2019, followed by finalized design by early 2021 and construction as soon as 2021. See project schedule below.

View past updates on the project library page.

Project description

King County is beginning a green stormwater infrastructure project in north Seattle. This project will install facilities to help control a combined sewer overflow in Portage Bay. In 2017-18, the project team will study soil, groundwater, surface water flow, and street conditions in the project area to identify the best locations for facilities to be installed.

In this first phase of the project the County will consider what types of green stormwater infrastructure it should build, and where within the study area they should be installed. Some options include different types of bioretention and permeable pavement in alleys or streets. Learn more!

Project study area

The project will select sites for installing green stormwater infrastructure from within the area below.

Study area is near Green Lake, Seattle  Click to view more of map .

Approximate boundaries are intended for planning purposes only. Further study and evaluation will be completed prior to selection of any site.

Project need

In the University CSO Basin in Seattle, heavy rains can cause sewers to overflow into Portage Bay approximately six times per year. This project will install facilities to help control these overflows. Learn more about King County’s CSOs.

What is green stormwater infrastructure?

Green stormwater infrastructure—also called natural drainage—mimics nature by slowing or reducing polluted runoff close to its source. It also treats polluted runoff from roads, roofs, and parking lots by capturing and cleaning it before it harms our waterways. Learn more!

Your feedback 

The County will share its evaluation of two to four alternative ways of doing green stormwater infrastructure with the public, and ask for your feedback online and through community events. Visit the public involvement page.

Project schedule

4Q 2017 Alternative analysis begins

Early action project schedule

While construction for this GSI project will take place in 2021-23 (see left), the County plans to install early action projects in 2019.

1Q 2019 Alternative analysis complete
3Q 2019 Predesign complete
1Q 2021 Final design complete
2Q 2021 – 2Q 2023 Implementation (bidding, award, construction)


Contact us

Contact Dana West, Community Services, at:

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Green stormwater infrastructure installed at a Roosevelt neighborhood church:

The County’s green stormwater infrastructure project in West Seattle:

The big picture:

RainWise rebates:

  • Many residents of this area can install their own green stormwater infrastructure (rain gardens and cisterns) on their own property funded by an average $4,400 rebate. Check your eligibility and learn more .

houseThe County will consider installing different types of green stormwater infrastructure in the public right-of-way, including types of bioretention in planting strips and permeable pavement in alleys or streets.