AZ vs. CA:24 California Exhibits, Vol. XXIV; Miscellaneous

page 103

GREEN RIVER BASIN, WYOMING. This includes the entire Colorado Basin in Wyoming except that part drained by Vermillion Creek and Little Snake River. The Green River Basin covers an area of 15,000 square miles in southwestern Wyoming. The altitude of the basin is from 5,800 feet to 14,000 feet, but most of the irrigable land lies at an elevation between 6,000 and 7,000 feet. Average annual precipitation on the valley floor ranges from 6 inches in the south to 11 inches in the north, with 3 to 4 inches in the growing season. In the mountain ranges it is much more. The average annual temperature varies from 34° in the northern and higher parts to 42° at Green River. Coal mining and stock growing are the principal occupations of the 20,000 residents of the valley. Sixty-five per cent of these dwell in the coal mining towns along the Union Pacific Railroad or at Green River town which is a railroad division point for the Union Pacific. Most of the valley lies to the north of the railroad, some of the irrigable land being 100 miles north as the crow flies. Present irrigation development is generally in small individual areas mostly along bottom lands although some few fairly large projects have been built under the Carey Act. However, on these latter actual irrigation has progressed only to a small degree. While diversion from tributaries is not difficult, land reached from the main river, especially near the southern end, requires long main canals because of the'slack grade of the river. Many projects have been outlined by surveys. Especially, much development under the Carey Act has been proposed and several projects have been built. The total acreage under those permits, which also embrace Carey Act lands, is 403,000 acres. The area as & whole is not well developed. Present irrigation is supplementary to the stock industry, the crop being largely wild hay. Its future development will be also a supplement to stock raising but it is possible to raise grain and various root crops. The small precipitation and inability to spend large amounts in preparing the land because of the short growing season will always keep the amount of land watered per second-foot of diversion comparatively low. On the other hand, the short irrigation season keeps the total seasonal diversion down. Natural drainage is not good in parts and this with lack of precipitation and intense aridity will tend toward a rather high consumptive use of water. Diversion for entire basin is estimated 2.5 acre-feet annually and actual consumption of water 1.5 acre-feet. Power developments will always be small unless it is feasible to create head by dams on the main river. This possibility has not teen investigated. On the tributaries possibilities are small. The irrigation, as noted herein, will use all known reservoirs and if these plans are ever carried out, it must be at the sacrifice of some possible power. 103