TEMPORAL CHANGES IN PROGLACIAL STREAM TEMPERATURES IN WHITE RIVER, WA

Water temperature is a crucial component of water quality. Glaciers and snow in glaciated watersheds supply low temperature water during the summer melt season, which can help to counteract warming stream temperatures due to rising air temperatures and urbanization. Emmons Glacier located on Mount Rainier, WA supplies low temperature water to the Puyallup watershed via the White River. We measured stream temperature in White River at four sites located ~ 0.1 to 4 km from Emmons Glacier terminus. Data was collected using probes that were submerged in the river for 24 - 48 hour periods in June and July, 2016 - 2021. Meltwater temperatures within 0.2 km of the terminus are less than two degrees Celsius. Preliminary results show that meltwater temperature cycles diurnally, with peak temperatures occurring in the afternoon, and minimum temperatures occurring late at night or in the early morning; diurnal meltwater temperature fluctuations near the terminus are within one degree Celsius. These findings suggest that air temperature is the dominant influence on glacial meltwater temperature. At a site 4 km from the terminus, the water is one to five degrees Celsius warmer, and the diurnal temperature shift is larger, up to two degrees Celsius. The consistency of meltwater temperatures at the glacier terminus throughout our findings suggests that glacial melt may mitigate rising stream temperatures downstream.