The outstanding generalization about ground water in the parts of New Mexico and Texas in this region is that reserves will be exhausted in a few to several decades at the present rate of use. In nearly all areas development has increased exponentially since 1945. In New Mexico some legal check on exploitation is available in the doctrine of priority; in Texas no legal check exists.

Generalizations concerning the hydraulics of the important ground-water bodies are: most recharge is close to development; the localities of natural discharge are from a few to 100 miles distant; the exploitation of ground water by wells involves either the depletion of storage or a decrease in stream flow to which it is tributary.

The prolific aquifers are unconsolidated deposits of Quaternary and Tertiary age in bolsons, stream valleys, and the High Plains, and limestones especially of Permian and Cretaceous ages.

Bolson aquifers include the interconnected water bodies between the Basin Ranges of southwest New Mexico, the Estancia Valley, Tularosa Basin, and the Dell City areas. River-connected aquifers include the alluvium of the Rio Grande and the alluvium and limestones of the Pecos River and other Texas streams. The development of the Roswell Artesian Basin resulted in the New Mexico ground-water law, upon which the laws of nine other western states are modeled. Saturated brines enter the Pecos in the Delaware Basin.

The Staked Plains contains probably the largest area of ground-water mining, and one of the largest groundwater reservoirs in the United States. Its size made necessary the first application of a non-steady theory of ground-water movement 30 years ago and the widespread mining resulted in 1963 in the first legal determination that ground water is a depleting mineral resource.

The hydrodynamics, development, reserves, and depletion of individual ground-water bodies are given.

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