Understanding the impacts of surface-groundwater conditions on stream fishes under altered base-flow conditions
January 2014 - May 2018
- Oklahoma Department of Wildlife Conservation
Persistence of aquatic fauna depends on the conditions and connectivity of surface water and groundwater. In light of altered baseflows and the resultant increases in stream temperatures, it is important to assess current conditions, examine fitness of aquatic fauna, and evaluate water-management practices. This project is a collaboration between the Oklahoma Department of Wildlife Conservation and the Oklahoma Cooperative Fish and Wildlife Research Unit. Our study objectives are to determine 1) how changes in baseflow levels in the Kiamichi River influence hyporheic exchange, which correspondingly influences temperature at the reach scale; 2) temperature tolerances of stream fishes as a means to predicting how habitat complexity influences the fitness of stream-fish populations; 3) assess how dam releases influence the downstream temperature and dissolved oxygen regime during the low-flow period. We used the WASP model to predict downstream temperature in response to hypothetical reservoir releases (0.00, 0.34, 0.59, 0.76, 1.13, and 1.50 m3/s) of water at three temperatures (27.64°C, 26.00°C and 24.07°C) corresponding to release location from the dam. We compared predicted temperature time series with critical thermal maxima to quantify cumulative time when stream fishes experienced severe thermal stress downstream from Sardis Reservoir. The reduction rates of thermal stress against that of the control were calculated to quantify the cooling effect of each release scenario. Results from this project will provide the state agency with information on how water releases affect fish populations downriver and possible options for providing cooler water downriver of the dam.