Longfellow Creek Natural Drainage System (NDS) Project
Example of a natural drainage system.
Project description
Enhancing Our Communities with Natural Drainage Systems and Pedestrian Improvements
Seattle Public Utilities (SPU) is constructing natural drainage systems (NDS) at three sites in the Longfellow Creek basin. Natural Drainage Systems are built in the roadway shoulder (the space between the street edge and the property line) and are 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.
Natural drainage systems offer multiple community benefits, such as:
- Reducing drainage issues
- Improving pedestrian access, safety, and traffic calming
- Increasing landscaping and create urban habitat through vegetation and street trees
- Improving creek ecosystems
SPU has partnered with Seattle Department of Transportation (SDOT) on this project to provide pedestrian improvements at 24th Ave SW between SW Thistle and Barton streets and at the SW Kenyon St pedestrian bridge at 24th Ave SW. This project is funded in part by the Levy to Move Seattle.
Through the City of Seattle's Public Art Program, we've added artwork at the SW Kenyon St site. The artwork along with the pedestrian improvements and new natural drainage systems are designed to create space for the community to connect with neighbors and the surrounding habitat.
What’s Happening Now?
SW Kenyon St Site: Most of the natural drainage system and pedestrian improvements have been completed. Crews will finalize minor underground drainage and landscaping work between January and March 2026
Map of traffic control plan showing sections of 24th Ave SW and SW Kenyon St closed to vehicle traffic. The detour follows 24th Ave SW, SW Holden St, and 26th Ave SW, then reconnecting with SW Kenyon St. Also showing pedestrian bridge and walkway over Longfellow Creek and sidewalks on east side of 24th Ave SW and south side of SW Kenyon St remaining open.
During construction, residents can expect the following impacts in their neighborhood:
- Work will generally occur during weekdays, daytime hours
- Construction noise, dirt, dust, and vibration
- Materials and equipment will be staged near the roadway, close to active construction zones
- Parking restrictions and temporary lane closures near the work area
- Road closure on SW Kenyon Street and 24th Ave SW for the duration of the work
- During construction, the pedestrian bridge and walkway over Longfellow Creek and sections of 24th Ave SW and SW Kenyon Street will remain open to pedestrian
- Pedestrian and bicycle detours may change slightly, please follow all detour signage
Locations
This project includes three locations, which were selected based on a variety of factors that included community input, recurring drainage and flooding issues, and technical feasibility.
24th Ave SW (between SW Thistle and SW Barton St)
- New natural drainage system facilities from SW Thistle St to SW Barton St to improve stormwater drainage, slow down traffic, and improve water quality in Longfellow Creek
- New sidewalk along the west side of 24th Ave SW between SW Thistle St and SW Barton St
Sylvan Triangle (Sylvan Way SW between SW Orchard St and Delridge Way SW)
- New a large natural drainage system in the public right-of-way on Sylvan Way SW near Home Depot
SW Kenyon St (near the Longfellow Creek pedestrian bridge at 24th Ave SW)
- New walkway, bridge, and boardwalk for people to get to nearby schools, homes, and bus stops
- New natural drainage systems to reduce pollution in Longfellow Creek
- New art installation to enhance the space and connect community to the creek
Visit the site map to see where each site is located in the Longfellow Creek area and see below for more information about the final design and anticipated construction impacts for each of the sites.
Natural drainage systems are living systems and their appearance will change over time. The grasses, shrubs, and trees installed will grow and change as the garden matures. It may take up to three years for plants and shrubs in the natural drainage system to reach full maturity, and possibly longer for trees. The examples below show what a natural drainage system may look like over time.
Maintenance and Care
SPU is responsible for all maintenance needs of the natural drainage systems. This will include general upkeep of the natural drainage system plantings, checking that the natural drainage system is functioning properly, removing sediment, and replacing or removing plantings and trees, if needed. You will not be asked to perform any maintenance of the natural drainage system.
Community 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.
Community engagement
Through the City's Public Art Program, Portland-based artist Brian Borrello developed an art installation for the SW Kenyon St site. The public art was installed at the corner of 24th Ave SW and SW Kenyon St in late spring 2025 in collaboration with Portland-based artist Brian Borrello and the City of Seattle’s Public Art Program.
The artist's goals wee to make this place interesting for the community to visit and for the art to offer something unexpected, thought-provoking, and perhaps a little magical. This site is where life forces are nourished by the creek, where neighbors can connect with each other while they pass through, and where community can experience the natural world and its often-unseen processes.
Natural drainage systems slow stormwater and filter out pollutants before they can harm our creeks and other waterways. Keeping pollutants out of our water is important for fish, aquatic life, and people.
Building a natural drainage system in the Longfellow Creek basin is part of the Plan to Protect Seattle's Waterways. SPU used to call these "roadside rain gardens" but now calls them "natural drainage systems" or "NDS."
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.
Funding information
This project is paid for in part by the King County Flood Control District and the Levy to Move Seattle. Art at the SW Kenyon St site is funded through City of Seattle's Public Art Program.