Regional hydrogeology and the effect of structural control on the flow of ground water in the Rio Grande trough, northern New Mexico
— Lawrence M. Coons and Thomas E. Kelly

Ground-water flow in any porous medium is influenced by various hydraulic properties of the medium, together with hydrologic and hydraulic boundaries surrounding it or within it. Two rather distinct regimes of ground-water flow exist in the Rio Grande structural trough in north-central New Mexico from the Colorado border south to Espanola; the structure and stratigraphy of the Rio Grande rift effectively control the movement of shallow ground water in the area, and also the movement of a deeper ground-water body contained in saturated sediments of the Santa Fe Group. Where the cross-sectional area of Santa Fe Group sediments has been constricted or narrowed, in places like the Embudo "constriction" between Taos and Espanola near Pilar, mixing of the regimes occurs. Velocity and direction of shallow groundwater flow change and become similar to those of the deeper ground water in transient storage. The significant features of the Rio Grande rift region in north-central New Mexico are shown in Figure I.