Circular 46—Guides for development of irrigation wells near Clayton, Union County, New Mexico

By B. Baldwin and F. X. Bushman, 1957, 64 pp., 2 tables, 11 figs.

This preliminary report on part of Union County, in northeastern New Mexico, summarizes ground-water conditions in Clayton and Seneca 15-min quadrangles. The text, written for residents of Union County, emphasizes the way well data can be used. Technical data are presented in figures and tables. Geologic formations include basalt flows and the "Ogallala Formation" of late Cenozoic age; Graneros shale and Dakota group (Dakota and Purgatoire Formations) sandstone and shale, of Cretaceous age; Morrison Formation, "Wanakah formation", and Exeter (Entrada) sandstone, of Jurassic age; and Dockum group, of Triassic age. Simplified geologic maps for the two quadrangles (scale of 2 in per mi), show surface extent of basalt, Ogallala, and "bedrock"; bedrock includes Graneros shale and Dakota group. Fifty-foot contours on eroded bedrock surface beneath Ogallala Formation, constructed from 1,000 shothole logs and some outcrops, indicate local relief of 50-200 ft. Regional dip, according to 100 ft contours on base of Dakota Formation, is 40-50 ft per mi to the east-southeast. Geologic maps show location and elevation of 100 bench marks.

Hydrologic maps of the two quadrangles show data for wells. According to contour lines with 50 ft interval, the water table slopes eastward about 35 ft per mi. The maps also show areas where water will not be encountered in the Ogallala Formation. Low-yield wells may be developed almost anywhere in the area in the Ogallala Formation or Dakota group at depths less than 200 ft. High-yield wells may be developed: (1) in buried valleys filled by Ogallala, (2) in sandstones in the lower half of the Dakota group, and (3) possible in local sandstones at top of Morrison Formation.

Table 1 lists data for 410 domestic, stock, municipal (Clayton), industrial, and irrigation wells. Table 2 lists quality of water data for 36 wells. Water is hard to extremely hard, and for irrigation purposes it is excellent to good. Assuming a recharge rate of ½ in a year, 27,000 acre-ft is recharged in and west of the quadrangles in the ground-water tributary area of perhaps 1,000 mi2. Annual discharge by wells and springs west of the quadrangle is about 1,000 acre-ft. Within the quadrangle, the estimated annual discharge of springs and low-yield wells is 500 acre-ft, of municipal and industrial wells is 500 acre-ft, and or present irrigation developments, is about 5,000 acre-ft. A calculation made to check these figures indicates 14,000 acre-ft of ground-water flows east across the New Mexico line annually.