FRESHWATER CHALLENGES NEAR THE TEXAS-MEXICO BORDER - IMPLICATIONS OF UNMONITORED PRIVATE WELLS FOR HUMAN HEALTH

Communities living along the US-Mexico border face a disproportionately higher risk of exposure to the contaminated drinking waters from the abundant unmonitored private wells in the area (TGPC, 2022). The lack of access to safe drinking water and healthcare results in significant health disparities in the region, with the residents facing severe health risks and exposure to the environmental pollutants. A comprehensive observation about the freshwater quality influenced by the presence of contaminants and microbial population over the region is largely lacking, which is a critical issue to the population health. This study aims to highlight the hydrochemical facies of the regional groundwater and identify the major geochemical processes regulating the spatial variations in major ion chemistry and abundance of geogenic contaminants to ensure water safety in this area. Sampling has been conducted every six months since December of 2022 in Kinney, Maverick, Webb, and Zapata Counties (N=50). Current results were compared with the United States Geological Survey and Texas Water Development Board dataset that was collected from the surrounding areas. The comprehensive analysis of the current study includes testing for Dissolved Organic Carbon concentration and characterization of dissolved organic matter. Additionally, major cations, anions and trace elements concentrations measurements are under process. The presence of total coliforms and E. coli was detected using 3M Petri films. In-Situ analysis conducted in Webb and Maverick County showed an average pH of 7.06, Conductivity of 1376 μs/cm, and average temperature of 32°C . 3M Petrifilm results were negative for samples collected in Webb County (n=4), while one sample in Maverick County tested positive for E. coli and total coliform count (n=4). Previous findings in private wells surrounding the study area showed high levels of Mg (> 50 mg/L) , Sr (> 3000 μg/L) , Mn (> 100 μg/L) ,and Fe (> 100 μg/L) concentrations. We hypothesize that the unmonitored wells from the Texas-Mexico borderline counties are pumping groundwater from the same or connected aquifer system, making a significant proportion of these unmonitored household wells prone to potential contamination risks for the future.