Robert G. Myers

The San Agustin Basin, Alamosa Creek basin upstream from I Monticello Box, and the upper Gila Basin are located in parts of Catron, Socorro, and Sierra Counties in west-central New Mexico. There are four major aquifers within the study area: the San Agustin bolson-fill aquifer; the Alamosa Creek shallow aquifer; and the Datil and the shallow upland aquifers, which are present in all basins. Three minor aquifers, the Baca Formation at the northern edge of the San Agustin Basin, a basalt to basaltic andesite unit overlying the Datil Group in the San Agustin and Gila basins, and the Gila Conglomerate in all basins, produce some water. Potentiometric-surface maps were constructed to determine the hydraulic gradients of the San Agustin bolson-fill aquifer, the Datil aquifer, and the Alamosa Creek shallow aquifer. Dissolved-solids concentrations of water samples from all aquifers rangedfrom 74 to 23,500 milligrams per liter. The dominant cations varied; the dominant anion of freshwater generally was bicarbonate. Vertical electrical-resistivity sound ings were used to estimate the thickness of bolson-fill and the depth of the saline-water/freshwater interface in the San Agustin bolson-fill aquifer. Pointof-discharge temperatures of well or spring water that are greater than 21° Celsius are associated with faults in the areas of shallow or exposed bedrock. The dissolved solids concentration of warm water ranged from 120 to 1,200 milligrams per liter.

1988 New Mexico Geological Society Annual Spring Meeting April 15, 1988, Macey Center Online ISSN: 2834-5800

Pages: 25