Climate Change Impacts on Tacoma Power Watersheds


Lee, S-Y., Mauger, G., and L. Whitely Binder. 2015. Climate Change Impacts on Tacoma Power Watersheds. Report prepared for Tacoma Power by the Climate Impacts Group, University of Washington, Seattle.


In spring 2015, Tacoma Power contacted the Climate Impacts Group to update a 2010 analysis of climate change impacts on streamflows into reservoirs used by Tacoma Power to generate hydropower. This includes the Cowlitz River, the North Fork of the Skokomish River, and the Nisqually River. Climate and hydrologic projections were evaluated for the near-term future (2020-2049, or conditions representative of the 2030s)1 for use in analyses being conducted by Tacoma Power for their Integrated Resource Plan, which has a planning horizon of 2035. Tacoma Power also requested temperature projections for the City of Tacoma, which can affect power demand, and information on how climate change may affect streamflows and hydropower production on the Columbia River, which supplies over 50% of Tacoma’s power.