Chihuahua: a water reuse case in the desert

Groundwater from municipal and monitoring wells gives δ$^{18}$O and δ$^{2}$H values plotting in several fields that distinguish water sources as follows. Values are presented below as (δ$^{18}$O\permil,δ$^{2}$H \permil). Present-day Rio Grande water (-6 to-7, -62 to -66) is strongly affected by evaporation in New Mexico reservoirs. Groundwater from post-bomb infiltration in the river bed is similar. Groundwater from Texas includes non-evaporated water (-9, -63) associated with the flanks of the 1500 m Franklin Mts., and (-10 to -11, -70 to -78) probably derived from the 2500-3500 m San Andres and Sacramento Mts. in New Mexico. Groundwater with strong evaporation signatures (-5.5 to -9, -41 to -64) occurs east of El Paso, and may represent mixtures of river- and mountain-derived water, or evaporated surface water from lower basin elevations. Groundwater from Ciudad Juárez, (-11 to -12, -80 to -90), did not originate as present-day Rio Grande surface water or groundwater from the Hueco Bolson in Texas. Two hypothetical sources are consistent with isotope data: 1. Pre-dam snow-melt from Colorado, supplied as Rio Grande water; 2 Late Quaternary lake water from pluvial Lake Palomas, supplied by underflow from the adjacent Bolson de los Muertos area of Chihuahua. Historical water level data indicate that significant recharge from the Rio Grande was unlikely before aquifer development