Wintertime Thermal Refugia on the South Platte River Downstream of a Wastewater Treatment Facility

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Presenter Information(s)

Ryan Emmerson, Weston Burcar, Emily Melton, Gretchen Wilson, Jacob Casey

Abstract or Description

 Wastewater treatment plant (WWTP) effluent poses a significant thermal stressor— especially in arid and semi-arid regions. In the South Platte River near Denver, CO, WWTP effluent can comprise up to 85% of winter flow and raise temperatures above the wintertime chronic standard of 12.1°C for up to 11 miles downstream. These elevated temperatures can disrupt organisms and ecosystems, including temperature-sensitive biological cues in native fish (Figure 1 below). Thermal refugia—cooler water patches created by groundwater inputs, tributaries, or backwaters—may offer winter protection. However, their availability, spatial extent, and use by native fish like the Johnny darter are poorly understood. We investigate thermal refugia in Segment 15 of the river to inform management strategies to support native fish populations in effluent-dominated conditions

Mentor

Jordan Parman