Washington Park Arboretum Creek Headwaters Project
Updated: March 6, 2025
Spring 2025
What's Happening Now?
The consultant engineering and design team, Jacobs Engineering, has finalized the 60% Construction Drawings and is working toward 90% documentation and permitting approval. Recently geotechnical investigations, arborist tree assessments, wetlands reconnaissance, and existing drainage structure video inspections have been completed to help inform the design. The project team continues to coordinate with Seattle Public Utilities (SPU), the Seattle Department of Transportation (SDOT), King County, Washington State Department of Ecology (Ecology), Arboretum partners, and others to help ensure the project’s success.
Project Description
Arboretum Creek within the Washington Park Arboretum faces a lack of dry weather (summertime) flow that is important for stream health, specifically water quality and for aquatic and avian habitat. Friends of Arboretum Creek (FOAC) has identified several nearby springs, Alley and Alder Springs, as potential sources to supplement summer base flows. These springs were historically part of the Arboretum Creek watershed prior to the construction of Lake Washington Boulevard circa 1905.
FOAC and Seattle Parks and Recreation (SPR) are working together to reconnect Alley and Alder Springs to restore the natural hydrology of the Arboretum Creek watershed. In addition to the benefits to stream health and habitat, the project will be designed to capture and treat stormwater runoff that currently causes localized flooding both in the residential neighborhoods and proximate to the Japanese Garden entrance along Lake Washington Boulevard.
Location
Community Engagement
The project held a successful virtual Community Meeting, on October 15th, 2020, to review the latest design options and the visioning artwork. You can review the video of the meeting, or read the Executive Summary, on the FOAC website - Friends of Arboretum Creek. FOAC is continuing neighborhood engagement and raising funds for restoration and outreach while promoting a mutually acceptable design for uniting the uphill springs with Arboretum Creek.
Budget
The project is grant-funded by the King County Water Works and King County Flood Control Districts. Additional grant funds have been secured from the Aldarra Foundation and City of Seattle Neighborhood Matching Fund. FOAC and SPR are working together to secure additional construction funding from multiple sources to help bring this project to construction. Construction costs are estimated to be $2.5 million.
Schedule
Planning and Conceptual Design: 2017 – 2022
Construction Drawings and Permitting: 2023 – 2026
Construction: The project aims to be in construction in 2026, dependent on construction funding and permitting approval.
Project Documents
30% project designs can be viewed on the Friends of Arboretum Creek website.