New Mexico Geological Society Annual Spring Meeting — Abstracts

For most of June 2013, the Village of Magdalena could not produce water from their only well. It did not have sufficient water to pump; it had gone “dry.” Without being able to fill their Village storage tanks and supply the community, they were forced to truck in tanks of water and use bottled water. Over the following months, old wells were rehabilitated and the primary well gradually recovered enough water to produce again.

In reaction to the water outage in June, broad community concern developed about the local groundwater resources. To help address this concern, the New Mexico Bureau of Geology and Mineral Resources’ Aquifer Mapping Program began a watershed-scale hydrogeologic assessment. In this region of New Mexico, groundwater is found within fractured/faulted bedrock aquifers and thin alluvial aquifers. Wells are typically poor producers, commonly with 3-5 gallons per minute (gpm), while very few produce more than 100-200 gpm. Wells that can produce higher volumes are located in close proximity to the Magdalena Fault, which trends northeast-southwest through town.

During the summer of 2013, depth to water measurements were collected from 37 wells including Village and private domestic wells. Water level measurements were repeated in most of these wells in September 2013 and March 2014, in addition to installation of two continuous water level monitoring devices.

Looking at long-term trends, historical data from well drillers’ records and a water table map in a report by Summers (1975) provide a “baseline” for water levels in the area. Comparisons with the historic water levels suggest that in 2013, approximately 70% of the wells we measured had declines in water levels. Larger ~200-foot declines are observed on the east side of the Village, generally proximal to their primary pumping well.

Within a short-term perspective of 2013 and 2014, changes in depth to water are quite variable, which reflects the compartmentalized nature of the aquifers. Despite the sparse winter precipitation, most wells have higher water levels in March 2014 than in the summer of 2013. Since the water “crisis” in Magdalena in June 2013, water usage has also declined significantly. Continuous monitoring nearby the Villages’ primary pumping well shows that water levels have risen approximately 25 feet since that well “dried” up in June 2013.

As New Mexico faces challenges of reduced surface water supplies, with increasing temperatures and evaporation rates in the future, groundwater will become our most important resource. In areas like Magdalena with locally complicated geology, developing a detailed understanding of the regional geology, and how groundwater moves within it, is essential to a community’s future water supply.

References:

1. Summers, W.K., 1975, Ground-water resources of the Village of Magdalena, Socorro County, New Mexico: A hydrologic report on the results of test drilling during February 1975, Santa Fe, Consultants Report to Ralph E. Vail, 17 p.