The Effects of Hydropower Releases from Lake Texoma on Downstream Water Quality

Abstract

ABSTRACT Impacts of peaking generation on water quality in the tailwater of Lake Texoma, on the Texas and Oklahoma border, were evaluated during summer stratification in the lake. Sampling was conducted before, during, and after a daily generation cycle with measurements of temperature, dissolved oxygen, iron, manganese, and turbidity. Temperatures were near 25°C during generation, fluctuated 3–4°C during nongeneration, and increased in a downstream direction to near 28°C. Dissolved oxygen concentrations were between 4 and 6 mg L−1 during generation and increased in a downstream direction. During nongeneration, concentrations in the upstream regon of the tailwater were near 2 mg L−1 but were between 4 and 10 mg L−1 in the rest of the study area. Maximum concentrations, 6 to 10 mg L−1, were observed prior to the hydrograph peak at each station, suggesting leading edge effects of increased flow and aeration as substrate was covered during river stage increases. Concentrations of metals increased in a downstream direction coincident with turbidity increases from near 3 to 25 NTUs, suggesting resuspension and possibly flocculation. Dissimilar patterns were observed for nongeneration when concentrations decreased in a downstream direction while turbidity was relatively constant and lower than generation values, suggesting settling with decreased flow.