The southern Taos Valley, located just southwest of the Town of Taos, has experienced high growth in the last few decades. The increasing demand for domestic water is dependent on the long-term availability of groundwater. Much of the study area is unincorporated, and therefore the county government is responsible for approving or disapproving residential developments. Recently, a variety of residents (homeowners, farmers, developers, county officials, scientists, and others) have expressed concerns about the vulnerability of the groundwater aquifers in the region. The study area contains over 20 acequias and irrigation ditches, the Taos Country Club (18-hole golf course), the Taos Regional Wastewater Treatment Plant, Town of Taos production wells, several deep exploration wells, the Ponce de Leon geothermal area, and a vast amount of private land that could potentially be subdivided in the future. The geology and hydrogeology of the study area are complex; the aquifers and the quality of water range from excellent to poor, and the depth to water in wells ranges from shallow to deep and flowing artesian. The results of this study will demonstrate the complex hydrogeologic conditions that create such remarkable groundwater variations.