Presenter/s: Mark Ingman;Mousa Diabat
Symposium Session: 2024 - 05 Doing More with Less for the Love of Monitoring
Topics covered: adaptive management and monitoring, fish-salmon, modeling, and water quality
ABSTRACT
The Entiat River watershed in central Washington supports populations of chinook salmon, steelhead trout, bull trout, and lamprey. Among a number of factors, stream temperature impacts abovementioned species in the Entiat River. The Entiat River and its tributaries are projected to warm in the coming decades due to increased atmospheric temperature and decreased snowpack across the watershed. During the summer and early fall baseflow, water temperatures in rivers may exceed the thermal tolerances of salmonids. The objectives of this project are to analyze the summer thermal behavior and to locate cold-water inflows to the main channel of Entiat River and Mad River, and to identify opportunities for restoration projects that aim to enhance summer refugia and rearing habitats for salmonids. To achieve these objectives, during the summer of 2023 we collected high-resolution airborne thermal infrared (TIR) and true color imagery of 60 kilometers of the Entiat River, Mad River, and main tributaries. The TIR imagery was collected using an advanced cooled-technology sensor (FLIR SC6000, longwave TIR 8-9.2um) mounted to a helicopter’s floor which was flown at 400 m above ground level to achieve spatial resolution of 50 cm and temperature resolution was at a 0.1 ºC. Imagery was collected in the afternoon during summer when the thermal contrast is maximized between water in the channel and sources of cold-water inflow such as springs and hyporheic zones. The TIR data assisted in identifying several sites of cold-water sources and potential thermal refuges across the watershed. For each tributary, a longitudinal temperature profile was generated, which showed the thermal gradient of downstream cooling and warming that can be attributed to inflow from springs and tributaries (both cold and warm), riparian vegetation, and various environmental parameters. These data allowed us to identify the locations and hydrologic processes, such as groundwater discharge, that contribute to the maintenance of cold-water features within the drainage network that may function as refuges for salmonids and other cold-water fish.
This project’s analysis is added to the already on-going effort of mapping the watershed using a variety of technologies, such as topobathymetric lidar, and true color imagery, giving habitat-restoration planners to consider both the location of thermally suitable habitat and the physical processes contributing to it to and design future habitat restoration in the Entiat River watershed. Lastly, these data that constitute over 95% of the anadromous range for the Entiat watershed for cold water species will be made available for project managers in the Upper Columbia via the UCSRB data portal. The overarching goal is to encourage future restoration projects that are more strongly aligned with enhancing cold water habitat conditions.