EFFECTIVENESS OF BEAVER DAM ANALOGS AS A RESTORATION STRATEGY TO MITIGATE INCREASED WATER TEMPERATURES AND DECREASED DISSOLVED OXYGEN

Per the Clean Water Act, East Canyon Creek is impaired for dissolved oxygen (DO) due to decreased water flows, increased water temperatures, and river channel incision (TMDL 2010). Beaver dam analogues (BDA’s) are artificial beaver dams that can decrease stream temperatures and increase dissolved oxygen by elevating the water table and increasing connectivity between the floodplain channel (Pollock, 2014). This study evaluates how newly installed BDAs affect water quality in the Swaner EcoPreserve portion of East Canyon Creek near Kimball Junction, Park City, Utah. Two segments of the stream have BDA complexes, complex 1 with 4 BDAs and complex 2 with 5 BDAs. Water quality parameters including DO, total dissolved solids [TDS], conductivity, pH, and temperature were measured in-situ above and below BDA complex areas before and after installation. Parameters were measured during 14 sampling events over 20 weeks before installation of BDA’s, and 9 sampling events after BDAs were installed in September, 2019. Because water quality parameters change seasonally, mean delta values were calculated by subtracting the downstream value from the upstream value. This will isolate changes occurring within the BDA complex area independent of seasonal trends in parameters such as temperature. The mean delta of DO increased from 0.04 ppm (n=9) before BDA installation to 0.287 ppm (n=6) after installation in complex 2, and increased from 0.594 ppm (n=14) to 0.776 ppm (n=5) in complex 1. The mean delta of water temperature increased from -0.11 °C (n=9) before BDA installation to -0.095 °C (n=6) after installation in complex 2, and decreased from -0.027 °C (n=14) to -0.376 °C (n=5) in complex 1. Although DO increased after BDA installation at both complexes, temperature increased at one and decreased at the other. Other studies have shown that the full benefits of BDAs on stream water quality can take multiple seasons (Pollock, 2014), therefore stream monitoring will continue in the spring and summer of 2020.