Claire Utzman, a CREWS graduate student with the Upper Clark Fork River team, will defend her thesis on Monday, May 8 at 11 a.m. at the University of Montana.
Thesis Title: Quantifying Wastewater Nutrient Inputs to the Clark Fork River
Abstract: Though algae are at the base of food webs in many rivers, large algal blooms are increasing in frequency and can cause problems with nutrient cycling, depletion of oxygen supplies at night, and release of toxic chemicals. One leading cause of algal blooms is nutrient loading into rivers, and controlling nutrient release in wastewater is one approach that can be helpful in limiting algal growth. To reduce the intensity of algal blooms in the Clark Fork River in western Montana, numeric nutrient standards were put in place that regulated the release of the nutrient’s nitrogen and phosphorus into the river from wastewater. Past work showed decreased loading of total nitrogen (TN) and total phosphorus (TP) by 2009, though this work ended in 2009 and focused on only a subset of wastewater facilities in the basin. To expand our understanding of the loads of TN and TP from wastewater from a broader range of facilities from 2001 to 2022, I obtained data from the Montana Department of Environmental Quality (DEQ) from eight permitted facilities discharging wastewater effluent into the Clark Fork River. From these data I calculated loads of TN and TP from municipal wastewater to the river, which I then compared to loads in the river downstream of Missoula. Four wastewater treatment plants dominated nutrient contributions to the river over this time period. Over the last twenty years, wastewater loads to the Clark Fork have been reduced by 76% for TP and 70% for TN. This decline in wastewater loads is attributed to infrastructural improvements made to three of the wastewater treatment plants. Despite decreased wastewater TN and TP loads to the river, annual instream loads have not decreased. This may in part be due to annual loads in the river being driven by high values during the spring runoff period, when water velocity and sediment mobilization are maximized in the river.
Dr. Benjamin P. Colman, Department of Ecosystem Conservation and Sciences
Dr. Vicki Watson, Department of Environmental Studies
Dr. Ashley Ballantyne, Department of Ecosystem Conservation and Sciences
Dr. Alan Townsend, Dean, W.A. Franke College of Forestry & Conservation
Systems Ecology Presentation and Defense
Monday, May 8th, 2023 at 11:00 AM
Join in person: McGill Hall, room 210
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