Geology and ground-water resources of the Big Blue River Basin above Crete, Nebraska

Abstract

Most of the Big Blue River basin above Crete, Nebr., is underlain by sand and gravel of Pleistocene age that normally yields large quantities of water to wells. Deposits of till underlie the eastern part of the area, and here ground-water supplies are not abundant.Generally, the ground water is of the calcium bicarbonate type; however, some water in the western part of the area has appreciable amounts of sulfate. The high sulfate may be attributed to oxidation of iron sulfides in the Niobrara formation. Because of its low total salt content, low boron content, and low percent sodium, the ground water is suitable for irrigation. Although the water is hard and locally contains high concentrations of iron, it generally is potable and suitable for domestic use.The general movement of the ground water is eastward toward the main stem of the Big Blue River.Principal sources of ground-water recharge are precipitation on the area and underflow from adjacent areas to the west. Streams in the area generally receive water from, rather than contribute water to, the ground-water reservoir. As of 1953, the natural discharge of ground water into streams was about 150,000 acre-feet per year and was much more than the amount pumped from wells.The major use ma^ie of ground water in the area is for irrigation. About 60,000 acres is irrigated annually. The annual withdrawal of ground water for irrigation is about 61,000 acre-feet; for domestic and stock use, about 25,000 acre-feet; and for municipal use, 8,000 acre-feet.The number of irrigation wells increased from 14 in 1938 to 672 by June 30, 1953. During 1948, 140 irrigation wells were constructed, and the average rate of construction from 1944 through 1952 was 53 wells per year.Use of ground water for irrigation is steadily increasing, but in most parts of the area the available supplies are more than sufficient for present withdrawals. The past average annual rate of increase in ground-water withdrawals, if distributed over the area, could continue for perhaps 25 or 30 years without serious depletion of the ground-water reservoir, but the base flow of streams in the area probably would be reduced considerably. Because of the interest in, and the rate of development of, the ground-water resources, systematic collection of more adequate hydrologic data should be undertaken, and detailed quantitative studies should be made so that the perennial yield of the aquifer can be determined before serious depletion of the ground-water supply occurs. 1 2 GEOLOGY AND GROUND WATER, BIG BLUE RIVER BASIN, NEBR. ADAMS' CLAYFIGUKE 1. Index map showing location of the Big Blue River basin above Crete, Nebr. PURPOSE AND SCOPE OP THE INVESTIGATIONNearly all domestic, municipal, industrial, and irrigation water supplies in the area are obtained from wells. The use of ground water for irrigation is rapidly increasing, and this study was made in order to gain a better understanding of the geology and hydrology of the area as they pertain to the replenishment, discharge, storage, and additional develop...