Water-level changes in the High Plains aquifer, predevelopment to 2002, 1980 to 2002, and 2001 to 2002

Abstract

Printed on recycled paper The High Plains aquifer underlies one of the major agricultural regions in the world, including parts of eight states—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. In the 104.5 million-acre area overlying the High Plains aquifer, not including areas with little or no saturated thickness (fig. 1), the total number of acres irrigated with ground water increased rapidly after 1940. Irrigated acres comprised 2.0 percent of the aquifer area in 1949, 13.1 percent in 1980, and 13.3 percent in 1997—(Heimes and Luckey, 1982; Thelin and Heimes, 1987; U.S. Department of Agriculture, 1999). Water-level declines started to occur in the High Plains aquifer soon after the beginning of extensive ground-water irrigation. The water-level declines in the High Plains aquifer occur because of an imbalance between discharge, the largest component of which is ground-water withdrawals for irrigation, and recharge, which is primarily from precipitation. By 1980, water levels in the High Plains aquifer in parts of Texas, Oklahoma, and southwestern Kansas had declined more than 100 feet (Luckey and others, 1981). Water-level declines may result in increased costs for ground-water withdrawals because of increased pumping lift and decreased well yields. Water-level declines also can affect ground-water availability, surface-water flow, and riparian areas. In response to the water-level declines in the High Plains aquifer, the U.S. Geological Survey, in cooperation with numerous Federal, State, and local water-resource agencies, began monitoring more than 7,000 wells in 1988 to assess the annual water-level change in the aquifer. The purpose of this report is to present water-level changes in the High Plains aquifer from the time prior to substantial ground-water irrigation development (about 1950, which is termed “predevelopment” in this report) to 2002, 1980 to 2002, and 2001 to 2002. The water-level measurements used in this report were collected in winter or early spring when irrigation wells generally were not pumping and when water levels generally had recovered from the stress of pumping during the previous irrigation season. Figure 1. Water-level changes in the High Plains aquifer, predevelopment to 2002 (modified from Luckey and others, 1981 McGuire and others, 2003). WATER-LEVEL CHANGE, IN FEET Declines More than -150 -100 to -150 -50 to -100 -25 to -50 -10 to -25