New Mexico Geological Society Annual Spring Meeting — Abstracts

The southern Sacramento Mountains, defined in this study as the mountains south of U.S. 70 to Otero Mesa, are dominated by a 40-mile long, north-south trending crest with an average elevation of 8,000 ft amsl. The Sacramento Mountain crest is capped with Permian-age sediments of the San Andres Limestone and Yeso Formation, and these sedimentary rocks slope gradually to the east toward the Pecos River about 80 miles away. Water resources of the Sacramento Mountains have been studied extensively over the past several decades, particularly in the developed areas of Ruidoso, Cloudcroft, and Timberon, New Mexico. Two common themes have emerged from these studies: 1) most springs in the Sacramento Mountains occur at the San Andres-Yeso contact, and 2) the San Andres Limestone and Yeso Formation are considered as a regional aquifer hydraulically connected.

Results from deep well drilling at Cloudcroft demonstrate the primary groundwater system is perched in the San Andres Limestone and underlying limestone beds in the Upper Yeso Formation. Near the crest, the strata underlying this regional perched groundwater system is largely unsaturated with localized pockets of saline groundwater. The lateral extent of this regional perched groundwater system has been defined by groundwater-elevation and waterchemistry data. Farther east of the crest and down slope, the strata underlying the regional perched groundwater system contains a regional groundwater system approximately 200 ft lower in elevation and characterized by older water with chemistry different than the perched system. The regional perched groundwater system in the southern Sacramento Mountains covers approximately 300 square miles from Cloudcroft to Timberon, and is defined by groundwaterelevation contours greater than 6,600 ft amsl. This perched groundwater system is the primary source for springs and perennial streams in the southern Sacramento Mountains, and recharge to the Pecos Slope.