Predicting water quality data in an unfilled reservoir using microcosm sediment-water simulation

The technique of microcosm sediment-water simulation was used to obtain predictive water quality data for the proposed Jordanelle Reservoir, Heber City, Utah. Sediment-water microcosms were prepared for four sites located in the north arm of the reservoir basin, including two sites located in an abandoned acid mine tailings pond. Data obtained from the tailings pond microcosms indicated that low pH water and high trace metal concentrations may exist in this area of the reservoir. These data suggested that the tailings material should be contained or removed prior to reservoir filling. Other sites in the reservoir basin exhibited water quality considered normal for reservoirs of similar elevation and basin geology. Near the proposed dam, anaerobic conditions could develop rapidly due to available concentrations of organic carbon, and the subsequent release of Zn, Fe, and Mn may pose a water quality problem. At the sampling site near Keetley, simulation data indicated that anaerobic conditions will not develop as quickly or be as severe as conditions expected near the dam. Overall, the availability of nitrogen and phosphorus in the Provo River and Jordanelle sediments indicated that problems with algal blooms may exist in the reservoir. Also presented is a brief discussion of the advantages and disadvantages associated with microcosm sediment-water simulation.