Ground-water reconnaissance of the Green River basin, southwestern Wyoming

Abstract

This report describes the occurrence and quality of ground water in the Green River structural basin of Wyoming. Some general information concerning surface water has been included because of the close relationship of ground water to surface water in parts of the basin. The report gives the results of one of several ground-water reconnaissance investigations of large areas in Wyoming that are being conducted in cooperation with the Wyoming State Engineer. Each area generally coincides with one or more structural features that form relatively independent ground-water systems. The purpose of these studies is to obtain a general knowledge of ground water in previously unstudied parts of the State in order to locate potential water supplies for future development. The area of this investigation consists of approximately 10,000 square miles, and includes all of the Green River structural basin, which is about 60 per cent of the Wyoming part of the Green River drainage basin. It does not include the Wyoming thrust belt along the western side of the drainage basin, nor the Rock Springs uplift, the Washakie Basin, and the Sierra Madre uplift in the eastern part of the drainage basin. (See structural feature map.) Almost all of Sublette County and substantial parts of Lincoln, Sweetwater, and Uinta Counties are in the area studied. Major uplifts border the Green River structural basin on all sides. Much of the bordering highlands consist of high rugged mountains and, except for the Uinta Mountains in Utah on the south, are shown on the structural feature map. The high mountain areas in the north and south support pine and aspen, but the ridges and hills in the eastern and southwestern parts of the area are nearly barren. The basin floor, which ranges from about 6,000 to about 7,500 feet above sea level, is typified by treeless plains, mesas, and badlands. Altitude extremes are 13,785 feet at Gannett Peak in the Wind River Mountains in the northern part of the basin, and about 6,000 feet where the Green River leaves Wyoming in the southern part of the basin. The Green River and its major tributaries are shown on the streamflow map. Most of these streams flow nearly all year and reach their peak-flow stage in late spring. The numerous intermittent streams shown on the geologic map, but not on the streamflow map, flow for only short periods in response to precipitation. Climatic conditions in much of the south half of the area are arid and similar to those at the town of Green River which has an average annual precipitation of 7.9 inches. The temperature extremes for 60 years of record at Green River are -40° and +104°F, and the average annual temperature is about 44°F. Average annual precipitation at Pinedale near the foot of the Wind River Mountains and at Kendall near the head of the Green River are 10.6 and 16.9 inches, respectively. Monthly distribution of precipitation at Green River and Kendall is illustrated with the map showing streamflow. Precipitation in some years might be as much as 35 inches at higher altitudes in the Wind River Mountains. The principal known mineral resources of the area are water, trona, natural gas, oil, and oil shale; all except the latter are being developed. Other activities that support the economy are transportation, tourist trade, and agriculture. Agricultural activities include sheep and cattle raising throughout much of the area and the growing of native hay along the major stream valleys. About 385,000 acres of land is irrigated with surface water on the flood plains of the Green River and its tributaries. Much of the land in the Green River Basin is still public domain administered by the U. S. Bureau of Land Management. The Union Pacific R ailroad controls nearly all odd-numbered sections for 20 miles north and south of the railroad. Very little hydrologic work of a detailed nature has been done in the Green River Basin. A study in the Eden-Farson irrigation area by the U. S. Bureau of Reclamation includes some quantitative ground-water work. Considerable information about the geohydrology, but little quantitative information, is given by C. J. Robinove and T. R. Cummings (1963) in their report on a 300 square-mile area in the vicinity of Lyman. Other hydrologic reports have only very general information. They include publications by Gordon and others (1960), lorns and others (1964, 1965), and several unpublished studies of range well sites made by the U.S. Geological Survey for the U.S. Bureau of Land Management. WELL-NUMBERING SYSTEM