17th Ave NW Stormwater Improvements

Flooded street

Project description

Rain garden plantings
Natural drainage systems use special soils and plants to capture rainwater, clean it, slow it down, and soak it into the ground.

Reducing street flooding and sewer problems in Crown Hill by building natural drainage systems

Some parts of the Crown Hill neighborhood experience street flooding or sewer backups. The 17th Ave NW Stormwater Improvements Project will address the area with the largest, most frequent flooding problems.

Flooding and sewer problems happen during rainstorms on 17th Ave NW because runoff from a large upstream area hits undersized, shallow pipes under the street. When the pipes fill, water bubbles up from inlets and ditches overflow into the intersection. Because the pipes are full, there’s nowhere for water to go until the system drains. A challenge for fixing the problem is that blocks downstream from the project area also experience flooding and sewer risks — if SPU were to simply increase the pipe sizes on 17th, it could worsen the downstream problems.

This project will use a mix of pipe improvements and aboveground natural drainage systems to improve drainage while protecting downstream blocks. This will take pressure off the system and help it handle larger storm events.


The project will focus on the area between NW 90th Street and NW 85th Street. Most of the work will be along 17th Ave NW with some improvements on NW 87th St and NW 90th St.

Crown Hill Project site diagram
Crown Hill Project site diagram. Click to enlarge.

What's happening now?

We’ve developed draft alternatives to address the stormwater and sewer problems. This has included studying site conditions, hearing from the community (PDF), and talking to SDOT about different possible ways to fit the necessary improvements into 17th Ave NW. 17th Ave NW is a neighborhood greenway that provides important pedestrian bike and pedestrian connections for Crown Hill.

The project team is currently reviewing comments from the latest community engagement period this summer. We’re working to incorporate community feedback and new technical analysis as we move forward with the project. Thank you for your interest and participation in the 17th Ave NW Stormwater Improvements Project!

Community benefits

Middle school students walking
17th Ave NW is an important connection for students walking to and from Whitman Middle School. In wet weather, drainage problems make this route harder to use.

This project will significantly decrease the frequency of street flooding, a long-standing community concern. It will also decrease the risk of sewer backups to some homes on 17th Ave NW, and seek to address priorities from the City of Seattle’s recent community planning process, including the residents’ desire for pedestrian improvements and traffic calming on 17th Ave NW. Finally, increasing system capacity will help accommodate future growth.

What options are we looking at?

We are evaluating two possible project alternatives (PDF) that:

  • Reduce the flooding at 17th Ave NW and NW 87th Street without increasing flooding risk to downstream blocks
  • Are consistent with SDOT standards for safe and complete streets
  • Provide pedestrian improvements and traffic calming

To view a more in-depth explanation of the project alternatives, please view this video

Community involvement

We're committed to providing timely information and updates on project activities. Updates may be available in multiple formats: this website, emails, drop-in sessions, briefings, and/or public meetings. There will be several opportunities for the public to engage and provide feedback during this process.

We’re currently working to incorporate community feedback and new technical analysis into two alternatives for the project site. These alternatives will be available for public review and comment later in the fall. Check back for more information about upcoming opportunities to get engaged. Also, please consider signing up for project updates.

Phase 1 (2020 – 2022)

  • Gather background information, analyze site conditions, engage with previous community planning. Develop broader Crown Hill Stormwater and Sewer Plan analysis.

Phase 2 (2022-23)

  • Develop options

Phase 3 (2024)

  • Design and Permitting

Phase 3 (2025)

  • Construction

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

Newsletter Updates


Sign up for the latest updates from Public Utilities

Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.