New Mexico Geological Society Annual Spring Meeting — Abstracts

Over 1,000 water wells have been accurately located in Taos Valley and 1:24,000 scale maps have been prepared. Over 100 cross-sections were made to show structural and groundwater features. The largest Late Neogene feature is the Airport arch trending northeast across the Rio Grande rift basin. It is a southwest-plunging surface topographic high extending from the mountain-front to west of the Rio Grande gorge and flanked by gentle cuesta escarpments. The steeper east flank is highly faulted, down-to-the-east, into the El Prado-Taos basin. A series of four or more north-northwest-trending faults can be mapped with a combination of well control and surface fault expression from the Rio Hondo southward to the Picuris Mountains. The Rio Grande gorge follows in part, a north-south fault system, including one fault segment under the gorge bridge. East-trending valleys may reflect east-west fault systems. Blueberry Hill appears to be a fault-bounded horst block. Detailed water table data have been acquired in new subdivisions along the mountain-front at Weimer and Cañon Heights. Groundwater storage in fractures of tight Pennsylvanian rocks near the mountains is more limited than in Neogene clastics filling the rift basin. Many of the faults in Taos County appear to interrupt groundwater flow and compartmentalize the groundwater system. One hundred wells in the Questa area show a high water level north of town rapidly dropping to the Red River and Rio Grande local base levels. Multiple monitoring wells drilled at the Mountain View Grocery gas storage tank leak and the Taos Wastewater Treatment Plant show details of the water table gradient and seasonal and yearly water table variations.