Geohydrology of the Westwater Canyon Member, Morrison Formation, of the southern San Juan Basin, New Mexico
— Thomas E. Kelly

The San Juan Basin of New Mexico has long been considered as an area having very limited ground-water potential. Farmington, the largest city in the basin, as well as the City of Aztec, have depended exclusively on surface water from the Animas River for their municipal water supplies. Shiprock is dependent upon the San Juan River. Wells at Cuba, New Mexico, tap the Ojo Alamo Sandstone, however these are low- yielding wells that produce highly-mineralized water. Else where in the basin, isolated wells have been drilled at trading posts, as well as for stock and domestic purposes. However these have often been low capacity wells tapping the shal-lowest available aquifer.

 

Only Crownpoint, New Mexico, has had a dependable supply of ground water. The first four wells drilled at the community tapped Cretaceous strata, including the Gallup Sandstone and the shallower Crevasse Canyon sands. Well No. 5 was completed in the Westwater Canyon Member of the Morrison Formation in 1958 and well No. 6 was completed in the same deposit three years later. During this same period, a tremendous amount of information about the Westwater Canyon was being obtained in the Ambrosia Lake area where major uranium ore deposits were being mined from the West- water sandstones. As exploration for uranium has spread into the deeper parts of the San Juan Basin, it has become obvious that the Westwater Canyon is the principal aquifer in the southern part of the basin.

 

The economic importance of the Morrison Formation has led to the publication of a great deal of information concerning the geology of the formation and its various members. However very little data is available pertaining to the hydrology of these units. Although all the members of the Morrison have local economic importance, only the Westwater Canyon Member is an aquifer of regional significance. Therefore the purpose of this paper is to summarize the available hydrologic data and provide a general review of the hydrologic conditions in the Westwater Canyon Member of the Morrison.

 

The author gratefully acknowledges the information that was furnished by various mining companies, individuals, federal and state agencies.