Located at the headwaters of the Yakima River Basin, the Teanaway drainage provides water vital to the resilience of anadromous salmonids such as bull trout, steelhead, and Chinook salmon. Anadromous salmonids are adapted to spend a portion of their life cycle in freshwater, returning from the sea to rivers for spawning. These coldwater fish are reliant on sections of cold, freshwater habitat, referred to as coldwater refugia, to survive in freshwater. 

Climate change models predict that shifts in snowmelt and precipitation patterns will result in increased stream temperatures in the Pacific Northwest, and decreased area of thermally suitable habitat for coldwater fish in the Yakima River Basin. This reduction of thermally suitable habitat is exacerbated by the degraded conditions of the Teanaway River. Decades of forest management practices pulled large wood out of stream systems, resulting in increased rates of stream incision or down-cutting, a type of vertical erosion. Stream incision has progressively separated the Teanaway River and its tributaries from their active floodplains, reduced groundwater storage and exchange of groundwater with surface water. One strategy of climate adaptive restoration in the Teanaway Basin aims to recover groundwater storage and groundwater interaction lost due to channel incision. Such actions would recover lost natural water storage function on the landscape and are expected to improve late-season flows, encourage riparian forest revegetation, and decrease stream temperatures, all of which contribute to the resilience of the watershed and salmon populations to climate change. 

Casey’s research will examine how restoration of groundwater storage could reduce the loss of coldwater habitat for salmonid species in the Teanaway River Basin by mapping predicted stream temperatures and the degree of stream incision and restorable water storage throughout the Basin. Using remotely sensed stream temperature data, Casey will identify coldwater refuges and areas of climate vulnerability. This process can be combined with the stream incision map to analyze how the level of stream incision correlates with stream temperatures and identify where coldwater refugia could be further enhanced through restoration activities.

This project will build on previous work conducted by The Nature Conservancy and the Washington Department of Natural Resources to quantify the potential amount of restorable natural water storage achievable along the Teanaway River and its tributaries. Managers of the Teanaway Community Forest and surrounding public and private lands include members of the Tapash Forest Collaborative, made up of  the Washington Department of Natural Resources, The Yakama Nation, the U.S. Forest Service, the Washington Department of Fish and Wildlife and The Nature Conservancy. Casey will partner with members of the Tapash Collaborative and the Yakima Basin Integrated Plan Habitat Subcommittee, who can use the results of this research to integrate thermal restoration through floodplain water-storage recovery into overall restoration planning efforts.