Longfellow Creek Natural Drainage System (NDS)

What & Why 

We will construct natural drainage systems (NDS) at 3 sites in the Longfellow Creek basin. NDS consist of shallow depressions in the public right-of-way, or "planter strip," filled with deep-rooted plants and spongy soils that temporarily hold and clean polluted stormwater from streets and sidewalks before the stormwater enters our waterways.

Why Longfellow Creek? Longfellow Creek is a salmon-bearing urban creek with degraded water quality adjacent to where people live, work, and play. Stormwater picks up pollutants from streets-including oil, heavy metals, and fertilizers-every time it rains and flows into the creek through ditches or pipes. This project will remove pollutants from the stormwater before it reaches the creek.

The project FAQ contains more information.

What's happening now?

The team has completed our technical analysis of potential sites for the Longfellow Creek NDS project and selected sites that will move into the design phase. We selected sites based on a variety of factors that included community input, recurring drainage and flooding issues, existing soil conditions, and availability of off-street parking. The project FAQ has a complete list of factors weighed.

Selected sites can be viewed on this map. We are also partnering with the Seattle Department of Transportation to provide pedestrian improvements at most sites.

Selected Sites for Design:

  • 24th Ave SW between SW Thistle St and SW Barton St
  • Sylvan Triangle (Sylvan Way SW between SW Orchard St and Delridge Way SW)
  • 24th Ave SW and SW Kenyon St

Over the next few months we will:

  • Continue designing the natural drainage system for each site
  • Continue to engage with residents, businesses, and community organizations around individual sites

Throughout 2019 and 2020, our team will be hosting public drop-in sessions near site locations to speak with customers and get feedback on each site’s design. If you’re interested, please sign up to receive updates about upcoming drop-in sessions by clicking “sign up for project updates” on the far right of this webpage. We look forward to seeing you soon!

Project goals and benefits

This project will improve water quality in Longfellow Creek, as well as improve stormwater drainage, slow down traffic, provide pedestrian improvements, and beautify streets.

The project will also help the City of Seattle achieve its goal of managing 700 million gallons of stormwater runoff using green infrastructure by 2025.

Project Documents