Fauntleroy Creek Culverts Replacement Project (45th Ave SW)

Photo of spawning salmon in Fauntleroy Creek
Spawning salmon in Fauntleroy Creek (photo courtesy of Whitney Fraser).

Project description

Promoting a healthy urban watershed in your neighborhood.

Fauntleroy Creek is in southwest Seattle. The Creek drains a 149-acre area (.23 square mile), called the Fauntleroy Watershed, into Puget Sound.

There are three culverts, or structures that channel water under roads, on Fauntleroy Creek: the lower culvert at Fauntleroy Way SW, the middle culvert at 45th Ave SW, and the upper culvert at California Ave SW. 

The 45th Ave SW is the immediate focus of this project.The California Ave SW culvert includes both the publicly owned roadway culvert and a privately owned culvert beneath the parking lot of Fauntleroy Church, United Church of Christ. SPU and the Church are exploring potential work on the culvert. The Fauntleroy Way culvert includes a fish ladder that was replaced in the late 1990's and is not part of this project.

SPU prioritizes culvert projects based on the likelihood and consequences of culvert failure. Each culvert is evaluated using various criteria, including impacts to the environment, traffic, and community, as well as operations and maintenance. Through this evaluation process, SPU has identified the public roadway culvert at 45th Ave SW as the highest priority for replacement.

The purpose of this project is to reduce the risk of catastrophic failure of the culverts, improve creek resiliency to higher flows, and restore fish passage which supports Tribal treaty rights. Due to the condition and age of the culverts, repairing them is not a viable strategy. Thus, SPU is committed to proactively replacing its public culverts to reduce the risk of failure and mitigate storm-related flooding.


The culvert for immediate replacement is located at 45th Ave SW (near SW Wildwood Pl). 

What's happening now?

SPU has procured consultant services to support design completion. Now that the consultant team is onboarded, we have resumed our design process for the 45th Ave SW culvert.

SPU continues to investigate creek, drainage, sediment, utility, or other infrastructure issues within the Fauntleroy Creek drainage basin that may be addressed through this or other projects.

Community benefits

The purpose of the project is to reduce the risk of catastrophic failure of the roadway culverts and the associated potential impacts to health, public safety, and the environment. The project's goals and opportunities also include:

  • Improving creek resiliency to higher flows from anticipated climate change
  • Restoring fish passage, which supports Tribal treaty rights and SPU's commitment to racial and social justice
  • Considering community safety in culvert design
  • Enhancing the community's connection to the Fauntleroy watershed
  • Providing safer working conditions for SPU maintenance crews

What does the preliminary design look like for the 45th Ave SW culvert?

The 45th Ave SW culvert design is in the initial design stage. 

Please note that we are still in early design, and the final design is subject to change based on permitting requirements and Tribal feedback, community input, and coordination with property owners.

An engineered drawing of the proposed culvert at 45th Ave SW, which is slightly curved and crosses beneath 45th Ave SW.
A map of the 45th Ave SW culvert showing preliminary design for the proposed culvert

A watercolor sketch of a sandy creek running through a box-shaped culvert at the end.
Concept sketch of the culvert at 45th Ave SW

  • In the map image, we are looking down on the site as if we were up in the air. The new culvert is shown in blue, and the new creek alignment is shown by the blue dashed line. The new culvert is all below ground, as the creek is about 30 feet below the surface in the deep ravine. After construction, the surface will generally look the same as it does now, except with new pavement and other surface improvements.
  • The culvert will be 14 feet wide and at least 6 feet tall. The size of the new structure was determined by collecting existing creek data and using the Washington Department of Fish and Wildlife culvert sizing calculations, which account for climate change. This larger size will allow the creek to meander more naturally, which will support a healthy habitat and fish passage.
  • The new culvert has a slight curve that allows it to be more aligned to the public right-of-way. Compared to a culvert with an angle or bend, the curved alignment is preferred by Tribes and regulatory agencies. The curved alignment allows us to locate the culvert entrance on public property, unlike the upstream end of the existing culvert, which is on private property. The new alignment is expected to cross underneath private property, and SPU will work with the property owners accordingly.
  • SPU is proposing to add public amenities that will enhance the community's connection to Fauntleroy Creek. These amenities may include public walkways, overlooks of the creek, and informational signage. Stay tuned for future opportunities to share your thoughts on these amenities.
  • During previous community outreach efforts, SPU heard concerns about safety with future access to the new culverts. Some community members have expressed concerns that the larger culvert size will enable unauthorized use of the culverts. We are working to balance community safety, the need for our crews to safely access the culverts for maintenance work, and federal and state requirements for the culvert size to support fish passage.

Community engagement

Beginning with the project's early planning in 2018, we have met with many community members and hosted briefings in the neighborhood to introduce the project and gather feedback. We will continue to seek community feedback to inform the design phase of the project.

If you are interested in receiving updates about future opportunities for engagement, please subscribe to the project email list.

Past work

  • Evaluate suitable alternatives to replace the culverts
  • Coordination with the community and Fauntleroy Church on replacement options, opportunities to provide feedback
  • Recommend options to advance into design 
  • Complete geotechnical investigations
  • Complete land surveying
  • Preliminary design development for recommended options

2023 to 2024

  • Gather community feedback on design elements like fencing, paving, and interpretive signage at the proposed public overlooks
  • Perform additional analyses such as hydraulic modeling and stormwater impacts
  • Perform detailed design on features such as creek channel design, wall and culvert structure design and roadway features.
  • Apply for local, State, and Federal permits
  • Continued discussions with nearby businesses and homeowners including neighbors with property adjacent the creek/City right-of-way

At this time, design is anticipated to continue into 2023, with construction of the 45th Ave SW culvert anticipated in 2026 to 2027. Construction of the California Ave SW culvert would follow agreements on design between SPU and Fauntleroy Church.

Existing culverts in poor structural condition
Like many cities across the country, we are faced with having to repair and replace a lot of aging infrastructure. SPU prioritizes culvert projects based on the likelihood and consequences of culvert failure. Each culvert is evaluated using several criteria, including impacts to the environment, traffic, and community, as well as operations and maintenance.

Through this evaluation process, SPU has identified its public roadway culverts at 45th Ave SW and California Ave SW as high priorities for replacement. Due to their age and condition, repairing the public culverts is not a viable strategy. SPU is committed to proactively replacing its public culverts to reduce risk of culvert failure and mitigate storm-related flooding.

Existing culverts are barriers to fish passage
The culverts at 45th Avenue SW and California Avenue SW prevent fish passage in Fauntleroy Creek. In replacing its public culverts, SPU is removing barriers that prevent fish from accessing upstream habitat. Stream conditions in the middle and upper reaches of Fauntleroy Creek have been characterized as viable fish habitat by SPU fish biologists, independent consultants, and biologists from the Washington Department of Fish and Wildlife (WDFW).

While relatively small, Fauntleroy Creek watershed is in a healthier condition than most of the City's urban streams — it has good water quality, ample forest canopy cover, the protection of City ownership for most of its area, and excellent community stewardship. Compared to other watersheds in Seattle, Fauntleroy Creek has the low levels of poor-quality fish habitat and a lot of moderate quality habitat that can be restored. It also has the lowest pre-spawn Coho salmon mortality of all our urban creeks, which is a strong indication of good water quality.
Based on stream surveys, nearly all of the mainstem of the creek up into Fauntleroy Park was identified as "Type F" waters (this means fish-bearing or capable of supporting fish.) New culverts on Type F waters need to be designed to meet state and federal requirements for fish passage. The new culverts would be sized based on WDFW Stream Crossing Guidelines to meet fish passage criteria, which will likely require a larger size for the culvert replacements.

Restoring fish passage is critical to support Tribal treaty rights
U.S. Supreme Court decisions and federal law have consistently affirmed validity of the Treaty of Point Elliott (and other relevant treaties, collectively referred to as the Stevens Treaties) and associated Tribal treaty rights to hunt and fish in usual and accustomed areas. Tribes ceded their lands in exchange for rights to take fish, which carried the implied promise the U.S. government would not significantly degrade the resource. The Stevens Treaties impose a duty upon the State—including its municipal corporations—to refrain from constructing or maintaining culverts that block passage of fish to or from Tribes’ usual and accustomed fishing places. Culverts impeding fish passage to fish habitat violate Tribal treaty rights. As a public agency, SPU is committed to restoring fish passage and supporting Tribal rights and regional salmon recovery.

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

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Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.