Ground-water resources of the Bisbee-Naco Area, Cochise County, Arizona

Abstract

The Bisbee-Naco area is in southeastern Arizona and northeastern Sonora, Mexico. Annual rainfall averages about 17 inches. The basin fill is the principal aquifer and supplies about 95 percent of all water for domestic purposes. The total ground water pumped in 1985 was about 6,500 acre-feet. Of that amount, 2,200 acre-feet was used for domestic use and the rest was used for irrigation and livestock. Domestic use is expected to increase 20 percent by the year 2000. Water levels at the Bisbee well field have remained virtually unchanged since 1953, but water levels have declined about 25 feet in areas east and southeast of the well field.. The native ground water in the area is a calcium bicarbonate type and generally# is suitable for domestic use. Ground water downgradient from a mine-tailings pond contains 650 to 850 milligrams per liter of sulfate. Recharge occurs naturally through direct infiltration of rainfall along the mountain fronts and through subsurface inflow from adjacent areas. Some water is recharged through direct infiltration from a mine-tailings pond, sewage ponds, septic systems, and urban runoff.The potential for contamination exists from mine tailings, sewage, and urban runoff. No other sources of drinking water are readily available in the immediate area. Potential alternate sources of drinking water are the aquifers underlying Sulphur Spring Valley and San Pedro River valley. SUMMARY OF FINDINGS1. Population in the Bisbee-Naco area was about 12,300 in 1980.Projected growth is expected to reach 16,000 by the year 2000.2. Climate is arid to semiarid with mild year-round temperatures. The average annual precipitation is about 17 in., of which about 36 percent occurs during July and August. Recent interest by developers and artisans has revitalized the economy of the area.In 1980 the population of the Bisbee-Naco area was about 12,300 according to figures provided by the cities of Bisbee, Arizona, and Naco, Sonora.Population in the area is expected to reach 16,000 by the year 2000 (Jesse B. Brown, Southeast Arizona Governments Organization (SEAGO), written commun., 1985). This figure represents an increase of about 33 percent over the 20-year period. Nearly 70 percent of this increase is