2023 CSDMS meeting-095


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Controls on the drainage of 3 High Cascades lakes: Where does it come from, where does it go?

Alex Simpson, (he/him),University of Oregon Eugene Oregon, United States. asimps10@uoregon.edu
Leif Karlstrom, University of Oregon Eugene Oregon, United States. leif@uoregon.edu
Sarah Cooley, University of Oregon Eugene Oregon, United States. scooley2@uoregon.edu

The McKenzie River is a major tributary of the Willamette River, itself a major tributary of the Columbia River, and is the primary source of water and power for Eugene, Oregon, a city of 175,000 people. Young (Holocene) High Cascades volcanism defines the headwaters of the Mckenzie River basin, with a significant source at Clear Lake (13,000,000 cubic meters), fed by springs and yearly snowmelt. Upstream of Clear Lake are 3 seasonal lakes, Lost (256,000 cubic meters), Lava (308,000 cubic meters), and Fish (559,000 cubic meters), that fill up during the yearly snowmelt and slowly drain over a period of 1-2 months through Holocene age lava flows. We have established pressure transducers in Lost and Fish lakes, which will ground-truth lake volume time series using LiDAR and high-resolution satellite imagery timeseries. Downstream of Clear Lake are USGS stream gauges which appear to respond to the seasonal lake drainage via variations in base flow. We look at how seasonal lake drainage varies over time as a function of drainage area and snowmelt, as well as the controls these have on Clear Lake’s discharge. The volcanic terrain of the High Cascades creates an unusual hydrologic system in which seasonal lake drainage acts like a massive slug test, which is repeated year after year. This “slug test” could help elucidate the size and resilience of the High Cascades aquifer and the legacy of volcanic landscape construction on surface/subsurface hydrology.