Geohydrology of the Madera Group, western Estancia Basin, New Mexico
— David N. Jenkins

The Madera Group of Pennsylvanian age crops out or is present near the surface in over 1,036 km² (400 mi.²) of the western Estancia basin in Bernalillo, Santa Fe, and Torrance counties. In much of this area, the Madera Group is the only potentially water-bearing unit available for domestic, industrial, and municipal water-supply purposes. The scenic quality of the area and easy accessibility to jobs and other urban amenities in Albuquerque due to the completion of I-40 led to a pop-ulation boom in the western Estancia basin during the 1970's. One of the centers of this population boom is the Edgewood area, southwestern Santa Fe County, where more building permits are being granted and more lot-splits are being approved than any other area in that county. Approved subdivisions, plus others in various stages of planning, include thousands of lots as small as 1 ha (ha hectare; 2.5 acres). Many smaller lots, approved under older, less-strict regulations, or not approved at all, are present. Water supplied to these developments by individual on-site domestic wells or by community water systems must come from the Madera Group. Typically, liquid-waste disposal is by on-site septic tanks; although, cesspools are common.

 

The Madera Group is a highly anisotropic, multiporosity media with three-dimensional flow systems disrupted by structural and stratigraphic features. Ground water from the Madera Group is known to discharge to the Rio Grande and to the Estancia basin. Other discharge areas may exist. The use of ground water in the Madera Group is administered as part of the Estancia, Rio Grande, and Sandia declared underground water basins. The Sandia basin straddles the Tijeras Canyo —Monte Largo structural zone and contributes ground water by underflow to each of the other basins. This paper is concerned primarily with the geohydrology of the Madera Group of the western Estancia basin. The geohydrology of the Madera Group of the Sandia Mountains has been described by Titus (1980).