The Albuquerque Basin, also known as the Middle Rio Grande Basin (MRGB; Plummer et al., 2004), is defined by Thorn et al. (1993) to include the Santo Domingo Basin to the north, the Calabacillas and Belen Sub-Basins to the south, and the Hagan Embayment to the northeast. The Albuquerque Basin as thus defined is the second largest basin in the Rio Grande Rift, extending over more than 3000 square miles and containing over 14,000 feet of basin-fill deposits. The basin is bounded to the north by the Jemez Mountains, and to the east by the Sandia, Manzanita, Manzano and Los Piños Mountains. The western margin of the basin is defined by the Ladron Mountains, the Lucero and Nacimiento uplifts, and the Rio Puerco fault zone, a northeast-trending fault belt that separates the Albuquerque Basin from the Colorado Plateau (Plummer et al., 2004).
As New Mexico considers the use of desalinated brackish water (less than 10,000 mg/L total dissolved solid) to diversify the public water supply, many questions must first be answered. Where are the brackish water resources? What data are available? What exactly is the water chemistry? How feasible is it to use brackish water for public supply?
The Estancia Valley is a relatively flat-floored, closed physiographic basin with internal drainage, occupying ~2,000 square miles in central New Mexico. The valley, most of which lies within Torrance County, is bounded to the west by the Manzano Mountains, to the east by the Pedernal Hills, and to the south by Chupadera Mesa. The northern margin of the basin is less well-defined, merging with a high plateau area in southern Santa Fe County (Meinzer, 1911; Smith, 1957; White, 1994). Highest elevations in the Estancia Valley (>9,000 feet) occur along the western rim of the watershed, on the east flank of the Manzano Mountains. Lowest elevations (~5,900 feet) are found along the central topographic axis of the basin, where a north-south trending series of playas formed by deflation are incised into the valley floor (Bachhuber, 1982). Because the Estancia Valley is a topographically-closed basin, the only outlet for precipitation that falls within the basin boundaries is by evapotranspiration, primarily from the playa lakes.
Desalinated brackish water has been discussed in New Mexico as a possible alternative supply for drinking water. The communities of Tularosa and Alamogordo continue to explore using brackish water as a municipal water supply, and plans are quite advanced toward production. The communities in this region are actively seeking information to insure protection of fresh water supplies while implementing the use of alternate source water sources - brackish groundwater.
The San Marcial and Engle Basins are axially-linked basins of the southern Rio Grande Rift system that connect the Socorro Basin with the Palomas Basin to the south (Connell et al., 2005). The Engle Basin is an east-tilted half graben containing ~2,000 feet of basin-fill material. Compared to other groundwater basins of the Rio Grande Rift, information specific to these two basins is limited. The compiled data contains only 32 data points for both basins. This very incomplete record indicates water in these basins is relatively fresh, with only four wells exceeding 1000 mg/l TDS.
The Tularosa Basin is an elongate, north-trending intermontane basin of the greater Rio Grande Rift system, occupying approximately 6,500 square miles in south-central New Mexico. The basin is bordered by Sierra Blanca and the Sacramento Mountains to the east; and the San Andres, Organ, and Franklin Mountains to the west. The basin merges to the south with the Hueco Bolson, extending into west Texas. Extensive fault systems with several thousand feet of vertical displacement separate the basin from the east and west-flanking uplifts (Lozinsky and Bauer, 1991). As regional uplift progressed, concurrent erosion of the surrounding highlands has resulted in deposition of more than 6,000 feet of alluvial basin-fill material, consisting of unconsolidated to weakly-cemented gravel, sand, silt and clay deposited in a series of coalescing alluvial fans around the margins of the basin. The basin fill is underlain by consolidated bedrock, thought to consist largely of Paleozoic carbonates.
The Mimbres Basin is a structurally complex region in southwestern New Mexico, extending over an area of more than 5,000 square miles in parts of Grant, Luna, Doña Ana and Sierra Counties, and straddling the border with the Mexican Republic. The region has been subject to extensive geologic, geophysical, and hydrologic investigations over a period of almost a century, including Darton (1916), White (1931), Trauger (1972), Hanson et al. (1994), Hawley et al. (2000), and Kennedy et al. (2000). The Mimbres Basin is located at the intersection of the Basin and Range, southern Rio Grande Rift, and southern Transition Zone tectonic provinces (Mack, 2004). Dominant structural features in the region are northwest trending faults and folds associated with the Laramide orogeny, Tertiary magmatism and Quaternary tectonism (Finch et al., 2008). The greater Mimbres Basin is made up of an interconnected group of hydrologic sub-basins separated by fault-bounded uplifts, bounded to the east by the Goodsight Mountains, Sierra de las Uvas, and basalt flows and cinder cones of the West Potrillo Mountains. The Continental Divide defines the northern and western boundaries of the Mimbres Basin. The only major surface drainage in the basin is the Mimbres River (Hawley et al., 2000; Connell et al., 2005; Finch et al., 2008).
The Española Basin is one of the northernmost basins of the Rio Grande Rift in New Mexico, and has been subject to extensive investigations in the past several decades (e.g., Kelley, 1978; Manley, 1979; Cordell, 1979; Golombek, 1983; Biehler et al., 1991; Johnson et al., 2008; Grauch et al., 2009). Although the Española Basin has the general form of a west-dipping half-graben, it exhibits a high level of structural complexity, consisting of a series of narrow, deep axial troughs in an otherwise shallow basin (Ferguson et al., 1995). The basin is ~50 miles long and 18 to 40 miles wide, and is linked to the east-dipping Santo Domingo Basin to the south at the La Bajada constriction. The basin is connected to the north with the east-dipping San Luis basin at the Embudo constriction. The Santa Fe Embayment occupies the southeast corner of the basin.
The Palomas Basin is an east-tilted half graben ~35 miles long by 12 miles wide, bordered to the east by the Caballo Mountains and Red Hills, and to the west by the Black Range, Animas Hills, Salado Hills, and southern Sierra Cuchillo. The north end of the Palomas Basin is defined by the Mud Springs Mountains and several faults that intersect near Truth or Consequences, which separate the Palomas Basin from the Engle Basin to the north. The basin merges to the south with the eastern Mimbres Basin (Chapin, 1971). The Palomas Basin contains up to 6,500 feet of Tertiary alluvial fan and lacustrine sediments of the Santa Fe Group along its deep eastern margin, overlain by ~500 feet of alluvial fan and axial-fluvial sediments of the Plio-Pleistocene Palomas Formation (Mack, 2012).
The Jornada del Muerto is a north-south trending basin lying to the east of the main Rio Grande Rift system in Socorro, Sierra, and Doña Ana Counties, New Mexico. The basin is ~160 miles long, averages 20 miles in width, and deepens to the south. The basin is bounded to the east by Chupadera Mesa and the Oscura and San Andres Mountains, and to the west by the Caballo and Fra Cristobal Mountains and the San Pasqual Platform. The south end of the Jornada del Muerto Basin merges imperceptibly with the northeast end of the Mesilla Basin. Unlike the Rio Grande Rift basins to the west, the Jornada del Muerto is a broad syncline that plunges to the south-southeast, formed between east-dipping Paleozoic and Mesozoic strata along the Caballo-Fra Cristobal Uplift and west-dipping Paleozoic strata in the San Andres Mountains. The basin is thus not part of the late Tertiary Rio Grande Rift extensional system, and Santa Fe Group basin-fill sediments are generally less than 350 feet thick (Chapin, 1971; Lozinsky, 1987; Roybal, 1991). The Jornada Draw fault zone runs from north to south and roughly parallels the hinge of the syncline. This fault zone significantly affects the groundwater system in the central part of the basin (Newton et al., 2015).
