Water-level change in the High Plains aquifer underlying parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming results from differences in recharge from precipitation and ground-water withdrawals for irrigation. From the beginning of irrigation development (1940) to 1980, water levels declined in several areas, and exceeded 100 feet in parts of the Central and Southern High Plains. From 1980 to 1993, water-level declines continued in these same areas, but at a smaller annual rate. This smaller rate of decline was associated with above-normal precipitation during 1981-93 and a decrease in ground-water application rates. Declines exceeding 20 feet from 1980 to 1993 were common in areas of intense irrigation development in the Central and Southern High Plains. In the Northern High Plains, water levels declined 10 to 20 feet from 1980 to 1993 in parts of northeastern Colorado, northwestern Kansas, southwestern Nebraska, and the Nebraska Panhandle. Water-level rises exceeding 20 feet, however, occurred in the Southern High Plains of Texas. Also, rises of 10 to 20 feet occurred in parts of southeastern and south-central Nebraska. The average area-weighted water level rose 0.21 foot from 1992 to 1993 in association was well-above normal precipitation in 1992. Water-level declines, however, continued in the intensively irrigated areas of the Central High Plains. Declines also' continued in the northern part of the Southern High Plains in spite of well-above normal precipitation. Water-level rises from 1992 to 1993 was widespread in eastern and southern Nebraska, northwestern and south-central Kansas, and in the southern two-thirds of the Southern High Plains of Texas in association with well-above normal precipitation in 1992. These rises exceeded 3 feet.
