Assessment of the Groundwater Resources of the Plains of San Agustin, New Mexico

Science Center Objects

The groundwater resources of the Plains of San Agustin basin are largely undeveloped, though recent interest in pumping and exporting some of these resources to the Albuquerque metropolitan area has caused uneasiness among some water-resources managers and the public. Protest and concern regarding this appropriation of water resources have been expressed by private, Federal, State, and Tribal entities because of potential effects on the available water resources within the Plains of San Agustin basin and in the Gila River watershed. Despite previous research efforts, questions persist about the region’s hydrologic conceptual model that limit the ability of decision makers to comprehensively manage this resource. Specifically, the degree of hydrologic communication between the East and West San Agustin sub-basins is unclear, and it remains undetermined if groundwater from the Plains flows into the Gila River watershed. A better understanding of the hydrologic conceptual model of the region will enhance the ability of water managers and researchers to evaluate the effects of changes in resource management.

USGS - Water quality sampling in the western Plains of San Agustin

USGS scientist Mike Carlson works to collect a water quality sample from a windmill in the western Plains of San Agustin. Photo taken by Jeff Pepin on April 10th, 2019.

PROBLEM: Prominent data gaps and questions remain concerning the groundwater-flow patterns within the Plains of San Agustin basin, such that the effects of exporting water from the area are difficult to predict. Accurate development of comprehensive management tools in the future, such as groundwater models, requires improvements to the hydrogeologic understanding of the area, including spring location and discharge rates, aquifer characteristics, recharge zones and rates, and groundwater-flow patterns.

 

OBJECTIVES: The objectives of this project are to (1) add to the characterization of the hydrogeologic framework of the Plains of San Agustin basin and (2) provide a comprehensive dataset to support future regional groundwater modeling efforts by compiling, collecting, analyzing, and interpreting pertinent data in and near the Plains of San Agustin. Specific emphasis is placed on evaluating the groundwater connection between the East and West San Agustin sub-basins, and between the San Agustin basin and the Gila River watershed.

 

APPROACH: Historical and newly-collected data will be analyzed and interpreted in the context of the hydrogeologic framework of the region. Compiled data will include relevant aquifer test results from published literature and water-level and water-quality data from the USGS National Water Information System (NWIS). Newly-collected data will primarily consist of water-quality data collected at ten to twenty sites to fill known data gaps in the western Plains of San Agustin. Interpretations will be documented in a USGS scientific investigations report.

 

RELEVANCE AND BENEFITS: This study will provide updated information on the water-quality and groundwater-flow patterns of the Plains of San Agustin basin on and near BLM lands and thereby allow the BLM to make more informed management decisions. The ability of interested parties to determine the effects of changes in resource management will also be improved by this study. Groundwater availability and movement are also addressed, which are priority issues for both the USGS Water Mission Area Integrated Water Availability Assessments Program and the USGS New Mexico Water Science Center Hydrogeology and Geochemistry and Water Sustainability Program Areas.

USGS - stock tank in the western Plains of San Agustin

USGS scientist Hal Nelson wades in a stock tank to install a fitting on the discharge pipe of a groundwater well to facilitate water quality sampling in the western Plains of San Agustin. Photo taken by Jeff Pepin on April 4th, 2019.