Longfellow Creek Floodplain Project
Existing floodplain habitat along Longfellow Creek at Graham St. Beaver ponds.
Project description
Promoting a healthy, accessible, and resilient urban watershed in your neighborhood.
Seattle Public Utilities (SPU) is working to reduce flooding and improve the health of Longfellow Creek in the North Delridge neighborhood.
Through the Longfellow Creek Floodplain project, SPU will evaluate the potential for creek and floodplain restoration at five locations along Longfellow Creek between the West Seattle Golf Course and Sylvan Way. Within this stretch, much of the creek’s historic floodplain habitat has been lost or degraded, leading to erosion, loss of natural flood storage, and poor habitat.
SPU will collaborate with North Delridge communities, the Longfellow Creek Network, the Office of Planning and Community Development (OPCD), the Department of Neighborhoods (DON), Seattle Parks and Recreation (SPR), and SPU's consultant team to center racial and social equity throughout this work. By partnering with community, we hope to combine our expertise, knowledge, and visions to ideate, create, grow, and succeed together.
Location
This project will focus on five reaches along Longfellow Creek between the northern end of the West Seattle Golf Course (Genesse St.) and Sylvan Way.
SPU is currently evaluating the five sites shown in this map to determine their potential for floodplain restoration.
What's happening now?
The Longfellow Creek Floodplain project is in the planning and options analysis phase. SPU has identified five potential sites along Longfellow Creek and is currently evaluating their potential for floodplain restoration and developing concepts for each of the sites. From these concepts, we will develop several restoration options, each of which may include one or more sites. These options will be further evaluated with input from community and City partners, and one option will be selected to move forward into the project’s design phase. Sign up for our email list to receive updates about the project and opportunities for public input.
Community benefits
Historically, Longfellow Creek was an important natural drainage system that provided valuable habitat. Unfortunately, historic development has dismantled and in some places eliminated parts of the creek, degrading this important ecosystem.
Existing problems in Longfellow Creek include:
- Excess stormwater and high peak flows due to historic development
- Flooding
- Erosion and channel incision
- Habitat degradation
Through this project, we have a chance to reconnect pieces of the creek in a way that improves drainage, adds resiliency to the creek, and invests in community needs and interests, such as improved access to Longfellow Creek and green recreation areas. Depending on the site(s) selected for restoration, there may also be opportunities for better trail connectivity along and across Longfellow Creek that will connect to the new transit improvements along Delridge Way.
What options are we looking at?
We are currently evaluating the potential for floodplain restoration at five sites. In addition to floodplain restoration, there may also be opportunities to address other habitat or infrastructure needs such as fish passage and culvert replacement or creek daylighting. We will package the site concepts into several options for further evaluation. We anticipate advancing design and construction at 1-2 sites.
Community involvement
Community input will play an important role in this project’s planning and design. As SPU develops concepts for the project, we will engage with the community to gather feedback and evaluate which options can best address community interests and needs. We recognize that there are already a number of City-led projects taking place in the Delridge Corridor, and we aim to incorporate themes we have heard during community engagement for these other projects into our project concepts. Sign up to receive email updates when public input opportunities become available.
- 2023: Assessed five potential sites and developed high-level concepts for two sites.
- Early 2024: Analyze the draft concepts for two potential sites
- Late 2024: Develop floodplain restoration options based on the results of the assessments and draft concepts
The Longfellow Creek watershed has experienced extensive industrial, commercial, and residential development. This development has fundamentally changed the watershed as wetlands and floodplains have been filled in, buildings have been constructed in the floodplain, and large sections of the creek have been piped and moved underground.
As creek floodplains have been eliminated and disconnected, peak flows in the creek have increased and erosion has narrowed and deepened the creek channel. These changes have caused flooding and property damage, fish habitat loss, and barriers to fish passage. The negative impacts of development and urbanization have degraded habitat and human connectivity to the watershed and eliminated many of the drainage benefits that a well-functioning creek can provide.
Through the Longfellow Creek Floodplain project, the City aims to make significant investments in the Longfellow Creek watershed, bringing multiple benefits to the watershed and the nearby neighborhood. Funding for this project was made available by SDOT and King County Meto, both of whom are required to provide stormwater flow control because of their work in the Delridge Corridor.
Rather than building costly underground detention vaults to manage stormwater, SDOT and King County Metro have entered into an agreement with SPU to develop an alternative approach to meeting these stormwater flow control requirements. The Longfellow Creek Floodplain project comes out of this agreement, as a project that will increase natural flood storage in the Longfellow Creek watershed while also providing multiple benefits to the ecosystem and community.