Temporal Variation of Water Quality from the Ogalalla Aquifer.

Abstract The Ogallala Aquifer (OA) is a large aquifer that covers eight states of the US and is among the largest aquifers in the world. In the Texas High Plains (THP), the OA is being depleted at a rapid rate because of agricultural and urban uses. In 2015, the High Plains Water District (HPWD) stated that in 50 years, 50% of the saturated thickness of the OA should be preserved. This restriction set by the HPWD did not address the quality of the remaining water. In general, the quality of water mined from the OA tends to decrease over time, as water located in deeper portions of the aquifer is more brackish. We hypothesize that with continued extraction of water from the OA more of the deeper, i.e., brackish water will be extracted, leading to an overall decrease in water quality produced by individual wells. To determine the temporal variability of water quality several wells spread across five counties of THP were sampled monthly for four years, starting in 2014. Results from temporal variability analysis, as well evaluation of water quality with depth are presented and discussed.