Groundwater Resources of the East Mountain Area, Bernalillo, Sandoval, Santa Fe, and Torrance Counties, New Mexico, 2005 Completed

The area includes parts of the Sandia, Estancia, and Rio Grande Declared Underground Water Basins, in which appropriation and use of groundwater are under the jurisdiction of the New Mexico Office of the State Engineer (NMOSE). (In this study the area of Estancia Basin is taken as mostly that of the Estancia Declared Underground Water Basin.) As first characterized by Titus (1980), the East Mountain area is composed of several hydrogeologic areas, distinctive in subsurface geology, groundwater flow, and often, water quality. Water-bearing geologic units in the East Mountain area consist of limestone, sandstone, siltstone, and unconsolidated alluvium. Folding and faulting of these water-bearing units exists in some areas. In addition, highly varied water availability conditions, variable storage, fractured flow, and aquifer compartmentalization contribute to the complexity of the hydrogeology of the study area.

Recently, population has increased in the East Mountain area, particularly in the northwestern and eastern parts of the area, and more development is planned. Population in the study area at the 2000 census was about 33,000 people in 12,000 households; in 1990 22,000 people were in 8,000 households (U.S. Census Bureau, 2005). The population has continued to grow rapidly since the 2000 census. The density of permitted wells varies throughout the East Mountain study area because of the variation in development and lot size, wells installed prior to declaration of the underground water basin by the NMOSE are not included, some permitted wells are not shown because of inaccurate location, and many areas of development are serviced by community water systems. With many new and planned residential developments, the growth trend is expected to continue and has raised questions about the sustainability of groundwater resources and possible effects on surface-water flows. Concerns about the availability and sustainability of groundwater resources, and possible effects of development on groundwater quality by residents and New Mexico State legislators resulted in a cooperative study by NMOSE and the U.S. Geological Survey (USGS). This report was prepared in cooperation with the NMOSE.

PURPOSE AND SCOPE

This study documents current (2005) groundwater resources, water quality and composition, and trends in conditions in the East Mountain study area, and updates interpretations of hydrogeologic controls on groundwater flow. The geology and hydrogeology are described, including structural features and geologic units and the water-bearing characteristics, groundwater areas and movement, and effects of development on water resources. Existing data for the study area are compiled and presented. Additional data collection activities during this investigation focus on areas where few data existed or in newly developed areas. The well and spring data and the water-quality data are presented; water-level contours are shown on a simplified geologic map (Williams and Cole, 2007) of the study area (plate).

LOCATION OF STUDY AREA

The East Mountain study is about 400 square miles and lies in parts of Bernalillo, Sandoval, Santa Fe, and Torrance Counties in central New Mexico. The study area boundaries were selected to include surfacewater drainages from the eastern Sandia Mountains, South Mountain, and the San Pedro Mountains, which are thought to be areas of groundwater recharge. The study area includes parts of the following USGS 7.5-minute quadrangles (1:24,000-scale): Placitas, Hagan, Golden, Sandia Crest, Sandia Park, San Pedro, Tijeras, Sedillo, and Edgewood.

SELECTED REFERENCES

Titus, F.B., Jr., 1980, Ground water in the Sandia and northern Manzano Mountains, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Hydrologic Report HR-5, 66 p., map in pocket.

U.S. Census Bureau, 2005, 1990 and 2000 decennial census data sets: Accessed November 30, 2005 at: http:// factfinder.census.gov/servlet/DatasetMainPageServlet?_ program=DEC&_lang=en&_ts

Williams, P.L., and Cole, J.C., comps., 2007, Geologic map of the Albuquerque 30¡¦ X 60¡¦ quadrangle north-central New Mexico: U.S. Geological Survey Scientific Investigations Map 2946, scale 1:100,000.