Key goals of this project included:

1) Developing a Modernized Hydraulic Model: Creating an accessible, high-resolution hydraulic model covering the Skagit and Samish rivers, from their deltas upstream to Marblemount. The flood model incorporates the latest data on river and coastal flooding, dike failures, and future climate projections.

2) Building Shared Understanding: Engaging tribal, local, and state governments, as well as the agricultural and environmental sectors, to raise awareness about current and future flood risks, describe the model and modeling results, and gather feedback on the approach and outputs.

3) Visualizing Results: Providing clear, visual representations of flood depths, extents, velocities and durations to help the public and officials anticipate risks.

This project was led by a multidisciplinary team with deep roots in the Skagit basin:

- Swinomish Indian Tribal Community (SITC): Project lead and funding recipient.
- Skagit River System Cooperative (SRSC): Technical expertise in river processes and fisheries.
- Skagit Climate Science Consortium (SC2): A non-profit group of scientists, including scientists at University of Washington Climate Impacts Group (UW CIG), providing locally-relevant research to support climate adaptation.
- Northwest Hydraulic Consultants (NHC): Leading the technical development of the hydraulic model.

Click below for the GIS files (tif) and model files (downloadable zip)

The final report is hosted by the Skagit Climate Science Consortium

Funding for this work was provided by the National Fish and Wildlife Foundation. The project is a collaboration between the Swinomish Indian Tribal Community, Skagit River System Cooperative, Skagit Climate Science Consortium, and University of Washington.

Importantly, the work would not have been possible without the technical expertise and contributions of Northwest Hydraulic Consultants. The new flood model was built on an existing model developed by the United States Army Corps of Engineers, who graciously shared their model for use in this project. We would also like to thank the boards of directors for both SRSC and the SC2 for their support throughout the project.

The project team is immensely grateful for the time, expertise, and input provided by a variety of staff from tribal governments, local jurisdictions, state and federal agencies, and local organizations and individuals, on both the project direction and products. The December 2025 flood event provided a unique opportunity to gather high water marks; a special thanks to Skagit River System Cooperative, the Skagit Drainage and Irrigation District Consortium, and Northwest Hydraulic Consultants for coordinating and working collectively to gather high water marks for model validation.

Projects from the Climate Impacts Group