Longfellow Creek Water Quality Improvement Project

Photo of paper in typewriter
Poetry written with community members at Delridge Day. (Lead poet, Shane Knode)

Project Description

As caretakers of the health of Seattle's waters, Seattle Public Utilities is working on long-term planning to understand issues in our sewer and drainage systems and is working with community to plan those investments. These improvements protect the health of the public and Longfellow Creek. Repairing our pipes and building green solutions upstream in the South Delridge community (South Delridge, Roxhill, Westwood, Highland Park, Riverview, and Puget Ridge neighborhoods) allows SPU to clean and slow water before it gets to Longfellow Creek.

We want to understand your community's dreams for better streets, parks, and community spaces. We also want to learn how our work can support local businesses and improve public safety. We want to get the most out of funds we spend on sewer and drainage projects in your neighborhood and we need your help to build that plan and form partnerships. Why?

Partnerships allow SPU funds to go further when we use the same space for two or more uses.


The South Delridge community (South Delridge, Roxhill, Westwood, Highland Park, Riverview, and Puget Ridge neighborhoods).

What's Happening Now?

We are focused on understanding your community's dreams for better streets, parks, community gathering and open spaces. We are looking for partnership opportunities to support the projects you care about and are working toward. We also want to learn more about opportunities for economic growth and how our work can support businesses in these neighborhoods. With your help we can get the most out of the funds we spend on drainage and sewer projects to help realize community goals.

Thank you to everyone who applied to be a part of the Innovation Team! This group of community co-creators will guide and collaborate with the project team during the planning process. In the coming months, there will be more opportunities for community members that live, work, and/or engage in the South Delridge community to help us shape the work we are doing.

The project team is also currently collecting technical data and engaging with community stakeholders to learn more about their experiences during this early planning phase.

Community Benefits

We are focused on improving water quality in Longfellow Creek. To do this, we will be creative about ways to improve the health and wellbeing of residents, particularly youth and the elderly.
To improve environmental and public health we will seek partnerships with community members, schools, and other community organizations in the area. We are actively seeking ways to incorporate environment and health-related benefits into our project.

Community Involvement

There will be multiple opportunities to share feedback and learn more about the project.

Please check back here for more information about engagement events and other opportunities.


Late 2019 to Early 2020

  • Interviewing community members
  • Building our Innovation Team
  • Collecting data and compiling maps
  • Looking for opportunities and constraints


  • Evaluate which types of systems are most compatible with community needs and technical constraints
  • Innovation Team develops community engagement through the arts

Late 2020

  • Prioritize concepts that provide maximum benefits and minimum burdens
  • Reach out through arts and cultural events
  • Create a vision for the project together


Sewage and stormwater (runoff from roofs, streets, and sidewalks) from many older parts of the city, including areas within Delridge, combine into one network of pipes (a combined sewer system). In dry weather conditions, all flows in these pipes go to King County's wastewater treatment system (shown below).

Depicts the flow of sewer in dry weather, described in page text

During the heaviest rainstorms (shown below), combined sewers can fill to capacity and any excess of that combined mixture of stormwater (90%) and sewage (10%) can overflow to the nearest water body to prevent sewage from backing up into homes and streets.

Depicts sewer flow when in heavy rain situations, as described in page text.

In Delridge, the nearest water body is Longfellow Creek. These combined sewer overflows, or CSOs, contain contaminants that can make people sick and harm fish, wildlife, and the environment. In some parts of the city, there are two pipe networks in the street: one to carry sewage (separated sewer systems) and another to carry stormwater runoff (the "drainage system"). Seattle's drainage system discharges stormwater directly to creeks, rivers, lakes, and Puget Sound. Although there is no sewage in stormwater, it still can carry harmful contaminants such as from street runoff that can also make people sick and harm fish, wildlife, and the environment. In some parts of Delridge, there is a drainage system that discharges to Longfellow Creek.
In order to improve the water quality in the creek, we are looking for ways to reduce the amount of water entering the creek during heavy rainstorms and how to make our combined sewer system and drainage systems more flexible and adaptable in response to changing weather patterns due to climate change.