GEOCHEMICAL CHARACTERIZATION OF SEDIMENT AND WATER CONTRIBUTIONS TO LAKE BELTON, CENTRAL TEXAS

Lake Belton is an impoundment of the Leon River within Bell and Coryell counties, Texas. Major reservoir tributaries include Owl and Cowhouse creeks which contribute overland flow and groundwater discharge from karsted terrains of Edwards strata that dominate the Fort Hood military installation which encompasses the northwestern portions of the lake. Previous studies of spring hydrogeology within karsted aquifers in the region have shown groundwater discharge is derived from mixed sources of artesian discharge and epigene through flow. In order to evaluate fluvial contributions to Lake Belton, lake sediments and associated waters were analyzed for major/minor cations/anions from the Leon River, Owl Creek and Cowhouse Creek. Samples analyses indicate elevated level of sodium and magnesium coupled with low chloride content for Cowhouse Creek. Owl Creek contributions exhibit slightly elevated sodium and chloride concentrations. Leon River analyses indicate elevated chloride and sulfate concentrations with local increases in iron, phosphorous, potassium and sodium proximal to the US HWY 36.

Based on sediment and water analyses, no evidence of increased concentrations of heavy metals were detected from fluvial contributions derived from the Fort Hood military installation; only samples proximal to US HWY 36 indicate any potential elevated metals, which is to be expected with any major infrastructure proximal to a water body. Variations in sediment and water composition in Cowhouse Creek closely align with spring studies in the area that indicated a greater artesian component to the aquifer system, while composition variations in Owl Creek closely align with spring studies in the region that reflect a greater epigene flow component. Effectively, the results of this study reinforce previous spring investigations of groundwater variability as the major contributor of tributary stream flow to Lake Belton.