Water-level changes in the High Plains Aquifer, 1980 to 1999

Abstract

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 High Plains region, the total number of acres irrigated with ground water expanded rapidly after 1940: 1949-2.1 million acres, 1980-13.7 million acres, and 1997-13.9 million acres (Gutentag and others, 1984; 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 development. 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 southwestern Kansas, New Mexico, Oklahoma, and Texas had declined more than 100 feet (Luckey and others, 1981). In response to these declines, the U.S. Geological Survey, in cooperation with numerous Federal, State, and local water-resource agencies, began a groundwater monitoring program in 1988 to assess annual waterlevel change in the aquifer using water-level measurements from more than 7,000 wells. The purpose of this report is to present water-level changes in the High Plains aquifer from 1980 to 1999 and from 1998 to 1999. The waterlevel measurements used in this report were collected in winter or early spring when irrigation wells were not pumping. Map scale and density of water-level data preclude showing small areas in the maps of water-level change where the value may be more or less than indicated. WATER-LEVEL CHANGES, 1980 to 1999