Modeling Climate Impacts on Hydrology and Stream Temperatures

Kyra Freeman estimates streamflow with the USGS stream gauging method in the Upper North Fork Stillaguamish River

The Stillaguamish River, the fifth largest river flowing to Puget Sound, provides water resources used by local municipalities, agricultural operations, industry and First Nations Tribes, and serves as an important habitat for endangered salmon species. The Stillaguamish Tribe relies on the Stillaguamish River for both traditional and economic salmon fishing and for promoting cultural environmental stewardship practices. Along the North Fork Stillaguamish, the numbers of returning spawning Chinook salmon and Steelhead trout are already in decline.

The purpose of this project is to use projected global climate scenarios and numerical models to assess changes in snowpack, streamflow, and stream temperature in the North Fork Stillaguamish River basin. Identifying how projected climate change would impact the hydrology of the basin will help assist river managers in making decisions concerning future salmon habitats, including where to focus habitat restoration efforts in the basin to mitigate rising stream temperatures. The Stillaguamish Tribe will be able to use the analysis outcomes to estimate when low streamflows will occur, and where and when the warmest stream temperatures will appear. They can use this information to guide their river management plans, and more specifically, their riparian buffer restoration efforts.