Groundwater Geology of Taos County
— A. L. Benson

Accurate locations of water wells using handheld GPS units has allowed mapping of the geologic structure and water table over Taos County. The Rio Grande rift basin is complexly faulted, and these faults locally interrupt groundwater flow. West of the Rio Grande groundwater flow is deep and southeasterly toward a base level at the river. East of the Rio Grande gorge, groundwater recharge is mainly from mountain-front streams, and groundwater flows westward at shallower depths toward the river. A north-northwest-trending system of four or more distinct faults underlies the Taos Valley, extending from the Picuris Mountains to the Rio Hondo-Rio Grande intersection. Another fault system at the down-warped eastern edge of the rift basin underlies the town of Taos and the urban area along the mountain front. Many of these faults appear to compartmentalize the groundwater system. Groundwater quality is generally excellent. However, shallow wells may have septic contamination and wells along faults or mineralized areas may contain elevated levels of some chemical elements.