Water-bearing characteristics of geologic formations in northeastern New Mexico-southern Colorado
— L. Clay Kilmer

The oldest geologic units having some potential for utilization as aquifers in the guidebook study area are elastics of Permian and Pennsylvanian age exposed in the Sangre de Cristo uplift and present at depth in most of northeastern New Mexico. The Glorieta Sandstone of Permian age exposed on the east flank of the Sangre de Cristo uplift may have some potential for utilization. The Santa Rosa Formation of Triassic age is an aquifer locally, in Guadalupe County, New Mexico. The Chinle Formation of Triassic age yields small amounts of water locally to wells in Harding and Union Counties, New Mexico, and in Baca County, Colorado. The Exeter/Entrada Sandstone of Jurassic age is a local aquifer in Harding, Union and Baca Counties. The Morrison Formation, also of Jurassic age, has a locally-occurring sandstone member which is an aquifer, but generally the formation does not yield adequate water to wells. The Cheyenne, Mesa Rica and Dakota sandstones, of Cretaceous age, are aquifers of local importance in all areas. The Ogallala Formation is a primary aquifer of the High Plains in the conference area. Volcanic flows and cinder deposits of Tertiary-Quaternary age in eastern Colfax, western Union and northeastern Harding Counties are local aquifers. Quaternary alluvial deposits are aquifers in many locations, particularly in the major drainages within the conference area.