Preliminary estimates of effects of uranium-mine dewatering on water levels, San Juan Basin. [Code SJBRUS]

Most of the uranium mines in northwestern New Mexico will withdraw water from the Morrison Formation in the course of mining operations. Using three levels of projected uranium mining, a digital model was used to estimate approximate dewatering rates, effects on water levels in the Morrison Formation, and effects on streams to the year 2000. All effects are superimposed on other likely developments of ground water from the Morrison Formation. Planned or announced mines, a maximum of 33 by 1985, would produce 570,000 acre ft (7 x 10/sup 8/ m/sup 3/) of water by 2000. The dewatering rate would be about 36 ft/sup 3//s (1 m/sup 3//s) in about 1985, with drawdowns of 2,000 ft (600 m) or more expected near the deepest mines. By 2000, a projected medium range of development of 72 mines would produce about 1,300,000 acre ft (16 x 10/sup 8/ m/sup 3/) of water, and the dewatering rate would be about 90 ft/sup 3//s (2.6 m/sup 3//s). Drawdowns of 4,000 ft (1,200 m) or more might be expected near the deepest mines. By 2000, a maximum projected development of 105 mines would probably produce about 2,030,000 acre ft (25 x 10/sup 8/ m/sup 3/) ofmore » water, and the dewatering rate would be about 117 ft /sup 3//s (3.3 m/sup 3//s). By 2000, dewatering of uranium mines and other ground-water developments may reduce flow in the San Juan River by 0.04 ft/sup 3//s (0.001 m/sup 3//s), and flow towrd the Rio Grande valley may be reduced by 0.5 ft/sup 3//s (0.015 m/sup 3//s). The peak effect on flow to streams would not occur until long after the year 2000.« less