Creek Culverts
In Seattle there are 65 miles of creek; 21 creek miles are in pipes. When a pipe carries a creek under a roadway or other land area, we call it a “creek culvert.” Specific City departments (Seattle Public Utilities, Transportation, Parks) are responsible for the creek culverts on properties they own.
Our creek culvert projects include the completed Thornton Creek Confluence Project and the Fauntleroy Creek Culverts Replacement Program.
Seattle Creek Culverts and Fish
In Seattle there are five main salmon-bearing creeks (Pipers, Thornton, Taylor, Longfellow and Fauntleroy) plus several other streams that historically or currently support other fish (Licton, Schmitz, and Yesler).
Historically, as towns and cities developed across Washington, many creeks were put into creek culverts and built over. Creek culverts are barriers to fish passage when they make upstream habitat inaccessible.
There are 700+ creek culverts in Seattle, some of which may be fish barriers. In addition, old, damaged or undersized culverts can cause upstream flooding and/or downstream erosion.
We are responsible for 63 known fish passage barriers which includes 48 culverts on SPU-owned property. We are also responsible for many city-owned creek culverts on privately-owned property; this accounts for approximately ~125 parcels with creek culverts that are partially or wholly on private property.
We have technical documents about Creek and Shoreline Health in our Shape Our Water Reports.
In Washington, protection of fish life (including fish passage and aquatic habitat in urban creeks) is regulated by the U.S. Army Corps of Engineers (USACOE) and Washington Department of Fish and Wildlife (WDFW).
- USACOE issues permits and other authorizations for all structures or work within navigable waterways (Section 10 of the Rivers and Harbors Act) and for the disposal of dredged or fill material (Section 404 of the Clean Water Act)
- WDFW issues Hydraulic Project Approvals for work above or below the ordinary high-water marks of regulated watercourses
In 2013, a federal injunction required the State of Washington to increase efforts to repair or replace some state-owned culverts, and began giving heightened consideration to tribal comments during permit application review. The injunction established that the State of Washington open 90% of the habitat blocked by state-owned culverts by 2030.
Beginning around 2019, WDFW and USACOE stopped issuing permits for culvert repairs that extend the life of culverts unless the repairs also resolve the fish passage barriers.
Federal and State regulations are increasingly requiring that fish passage barriers be removed by owners as they fail or are replaced.
We are committed to meeting our regulatory responsibilities to fish-bearing creeks as part of our mission to foster a healthy environment through equitable stormwater and wastewater management, for today and for future generations.
We are developing a city-wide creek culvert strategy that is science-based while we continue to address known culverts at high risk of failure, critical parcels facing imminent redevelopment, and multi-benefit projects that help fish.
In 2025 and 2026, we will develop a Thornton Culvert Strategy to prioritize creek culvert capital investments and related property acquisition along Thornton Creek in NE Seattle. This process includes engaging regulators and Tribal Governments, and will integrate multiple priorities including fish passage, capacity and condition, and equitable high-value stormwater services. It will be a model for the City’s other fish-bearing creeks.
We have a creek culvert inspection program. In 2025, the program anticipates inspecting approximately 100 SPU-owned creek culverts. Inspection data will inform development of citywide strategies.