Effluent-impacted groundwater-surface water interactions in the Brazos River Alluvium Aquifer : a study on Bullhide Creek.

The primary recharge source to the Brazos River Alluvium Aquifer (BRAA), a water table aquifer in central Texas, is through direct precipitation on the floodplain. However, recharge provided by other sources, such as Brazos River tributaries crossing the alluvium is not well known. To quantify potential recharge from tributaries hydraulically connected to the BRAA and understand spatiotemporal interactions with the aquifer, Bullhide Creek was chosen due to its constant effluent discharge from a wastewater treatment plant and a 3-mile reach that interacts with the BRAA. Based on ionic and isotopic compositions, nutrient densities, and changes in flow measured throughout the studied reach, Bullhide Creek exhibits perennial streamflow after the wastewater contribution and gains flow from the BRAA during baseflow conditions. However, the creek may provide measurable recharge to the aquifer during periods of high flow through seepage to aquifer sediments adjacent to the channel and banks.