Managing the Thermal Resilience of Streams in the Face of Climate Change

By: Hailey Smith, PhD Candidate, School of the Environment, Washington State University

The Yakima River Basin (YRB) mirrors environmental problems reflected across the Columbia River Basin, including decaying water quality, more frequent droughts, and a decrease in viable habitat for endangered and culturally important aquatic species, such as salmon.

In the YRB, climatic changes in precipitation, air temperature, and snowpack are causing reduced stream flow and increased surface water temperatures that exceed the thermal limits of salmonids and other cold-water species (Hardiman & Mesa, 2014; Kock et al., 2019; Wagner et al., 2021). Managers are actively looking for ways to protect critical waterways from experience extreme increases in temperature, and one option they are exploring is the use of more effective shade through the restoration of riparian vegetation.

Like many locations in the Columbia River Basin, the Yakima River is expected to see warming temperatures that will alter the timing, volume, and form of precipitation that occurs. With expected decreases in the amount of cold water available during the summer during salmon migrations, water temperatures are expected to create thermal barriers for fish that need to swim upstream to spawning grounds.

Does implementation of effective shade through restoration of riparian vegetation on targeted tributaries have the potential to reduce projected river warming in the Yakima River Basin? Through this work, we will focus on exploring options for improving tributary temperatures that impact the temperature of the Yakima River and the confluence of the Yakima with the Columbia River. This study will use the NorWeST Stream Temperature Model framework (Isaak et al., 2017) and will simulate the impacts of three different climate scenarios on river temperatures in three different riparian vegetation scenarios co-developed with natural resources managers to evaluate the potential cooling from targeted restoration in the YRB.

Hailey Smith

Ph.D. Student, School of the Environment (Pullman)

Research interests: Impact of climate change on future river temperatures, targeted riparian restoration strategies

Advisor: Julie Padowski

This work was funded in part by:

The Transformation Network NSF grant. To learn more about the Transformation Network, please visit their website: https://transformimw.unm.edu/

This work was funded in part by:

The Rivers, Watersheds, and Communities NSF grant. To learn more about this NRT graduate training program, please visit their website: https://nrt-rwc.wsu.edu/