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00'2343 . . . CHAPTER III PROJECT DEVELOP~lEl\'T (Juniper uri1 t) erosion, on benches that have withstood erosion and are separated from the valleys by steep escarpments, and on river terraces that were laid dawn when the river was at a higher level than at present. The lands are scattered over a wide area but generalq are in large enough bodies to be readily diVided into efficient farm units for irrigation develop- ment. In general the unit lands have good natural drainage and the soils appear to have good hydraulic conductivity. Some artificial drainage, however, would be required on benches where the land bodies are unusually large, the depths to bedrock are shallow, and the surface slopes are less than 4 percent. Aleo drains would be required in some of the vaJJ.eys which do not have well developed drainage channels. The soils comprising the valley and terrace lands are principally alluvial, while those of the benches are generally residual. Despite the prevailing semiarid climate, the soils have sufficient organic mate- rial for successful crop production. In their present state, the soils support growths of grass, sagebrush, and greasewood and with irrigation development they should be quite productive. Salinity and alkalinity are moderately low in the unit lands. Some areas, however, were classi- fied as class 6 (nonarable) because of high salinity or a combination of high salinity and alkalinity. Land use is influenced to a marked degree by climate. The average frost-free period is 123 days and the average irrigation season is 153 days. Precipitation averages about 8 inches annually, 3 to 4 inches of which usually occurs from early May through September. \lith adequate irrigation provided by the Juniper unit, the clima- tological conditions will allow a rather diversified type of agricultural development. The lands of the unit could be devoted to the production of cash crops, small grains, alfalfa, and pasture. Sheep production and dairying would probably be dominant on a majority of the farms. Water supply Ilith the Juniper unit in operation over the 1929-43 study period, irrigation supplies for the unit lands would have averaged 308,900 acre- feet annually at the turnouts of the main canals. This suppq would average about 99 percent of ideal requirements. Stream depletions re- sulting from the Juniper unit over the period of study would have aver- aged about 225,855 acre-feet annually. Repayment The payment capacity of irrigators on the Juniper unit would average ;P596,180 annually, including $Z76,400 required for operation, maintenance"and replacement costs and ~3l9,780 that would be available for amortization of construction costs. :iith the estimated annual pa;ymen't 46