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 Mesilla Basin is one of the southernmost basins of the Rio Grande Rift system, extending from south-central New Mexico across state and international boundaries into west Texas and northern Chihuahua, Mexico. The hydrology of the Mesilla Basin region has been subject to extensive investigations for over a century (e.g., Slichter, 1905; Theis, 1938; Sayre and Livingston, 1945; Conover, 1954; Leggat et al., 1962; Hawley et al., 1969; King et al., 1971; Wilson and White, 1984; Hawley and Lozinsky, 1992; Nickerson and Myers, 1993; Kennedy et al., 2000), as summarized by Hawley et al. (2001), who is paraphrased here. The eastern margin of the Mesilla Basin is defined by the Organ-Franklin-Juarez mountain chain, and the western margin by fault block and volcanic uplands of the East Potrillo Mountains and West Potrillo basalt field. The Robledo and Doña Ana Mountains define the northern end of the Mesilla Basin. The northeast end of the basin is transitional with the Jornada del Muerto Basin. The southern basin boundary with the Bolson de los Muertos in northern Chihuahua state is less well-defined. The entrenched Mesilla Valley of the Rio Grande crosses the eastern margin of the Mesilla Basin, where the cities of Las Cruces, NM, El Paso, Texas, and Juarez, Mexico exploit groundwater resources from the basin aquifers. Regional groundwater and surface water flow is to the southeast toward El Paso, through a gap separating the Franklin Mountains from Sierra Juarez to the south.
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).
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 High Plains aquifer is one of the largest freshwater aquifers in the world, covering more than 170,000 square miles and extending across parts of eight states from South Dakota to the Texas Panhandle (Sophocleous, 2010). The first regional investigation of the High Plains was conducted by the U.S. Geological Survey at the beginning of the 20th century (Johnson, 1901). Since then, several regional studies have been conducted (e.g., Gutentag et al., 1984; Weeks et al., 1988), and a great many more localized investigations (e.g., Joeckel et al., 2014; Chaudhuri and Ale, 2014), reflecting the societal and economic importance of this very extensive aquifer system.
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 Socorro and La Jencia Basins are located in Socorro Co., New Mexico, and define a transition where the Rio Grande Rift system broadens into a series of parallel basins separated by intra-rift horst blocks (Chapin, 1971). This broadening represents a general southward increase in crustal extension along the Rio Grande Rift (Adams and Keller, 1994). The Socorro Basin is hydraulically connected to rift basins to the north and south by flow-through drainage of the Rio Grande and southward flow of groundwater through alluvial sediments of the Rio Grande valley. By contrast, the La Jencia Basin has no perennial stream drainage (Anderholm, 1983). The two basins are separated by the Socorro Peak-Lemitar Mountains intra-rift horst, which splits the rift into two semi-parallel halves (Chapin, 1971), and restricts groundwater flow between the basins.
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 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 San Luis Basin is the northernmost and largest basin of the Rio Grande Rift system in New Mexico. Most of the basin is located in Colorado, where it merges to the north with the Upper Arkansas River graben (Grauch and Keller, 2004). The basin is ~150 miles long and 55 miles wide, and has the general form of an east-dipping half graben. Basin-fill material is composed of Tertiary-Quaternary sediments of the Santa Fe Group and late Cenozoic volcanics (Kelley et al., 1976). The basin is bounded to the west by the Tusas and San Juan Mountains and to the east by the Sangre de Cristo Mountains and the Sangre de Cristo fault zone. The deepest part of the basin is found in the Taos graben, a narrow zone 6 to 18 miles wide adjacent to the Sangre de Cristo mountain front (Grauch and Keller, 2004). The southern part of the basin is occupied by the Taos Plateau, which is composed of Pliocene basalt flows that overlie Santa Fe Group basin fill. The southeastern margin of the basin is defined by the Embudo fault zone, which separates the east-tilted San Luis Basin from the west-tilted Española Basin to the south (Bauer and Kelson, 2004).
