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Show WATER FOR UTAH the east and north and flows southwesterly across Washington County, leaving the State near the corner of Utah, Arizona and Nevada. It empties into the Colorado at Lake Mead. Thus, this basin is a part of the Lower Colorado and not of the Upper Colorado River Basin. The Santa Clara River, which drains the mountains to the north, the major tributary. Kanab Creek drains is a portion of Kane County and then flows south through the county and empties into the Colorado. The irrigated agriculture is largely in the valleys along the major streams. The major part of the land area is used for livestock grazing. Although the natural stream flow is variable, high in the spring and extremely low during the summer, there is practically no storage on the Virgin River or its. tributaries. There are no importations of water into the basin nor any exportation of significance. ... Irrigation and Power Development... The total irrigated acreage is only 23,700. Of this only 3,500 has a full supply, while the balance of 20,200 has only 65.1% of full supply. The shortage amounts to 18,800 acre- feet, while the total present supply is 45,000 acre- feet. The total irrigated acreage, 23,700, is 44% of the total arable acreage of 53,300. The present developed water supply is only 26.4% of the amount required to irrigate adequately all the arable acreage. ( See Table 19.) The total population of the area was a little less than 12,000 in 1940. St. George, the largest city, had a population of 3,591. There is no railroad in the area and practically no industry. The requirements for water for purposes other than agriculture are small. Investigational work designed to increase the supply of irrigation water has resulted in proposals for the development of an additional 56,- 300 acre- feet, or more than the present supply. This would all be developed within the basin. It is proposed that 2,800 acre- feet be used to provide an adequate supply for 8,200 acres that are now inadequately watered. However, there would be 12,000 acres remaining with only a partial supply, with less than 50% of a full supply. Thus far, specific plans for providing these lands with additional water have not been developed. The other 53,500 acre- feet of water would be adequate for 13,000 acres of new land. The consummation of these proposals would result in 36,700 acres of irrigated land with a supply of 86.4% adequate as compared to the present acreage of 23,700 acres with a supply only 70.5% adequate. The present and the planned development would irrigate adequately about 60% of the arable lands in the basin. ( See Table 20.) The proposals for the development of additional water involve the construction of a reservoir on the Virgin River three miles northeast of Hurricane. The water from this would be used for supplemental irrigation and for irrigating new TABLE 19 PRESENT ANNUAL REQUIREMENTS AND USE OF WATER FOR IRRIGATION IN THE VIRGIN RIVER DRAINAGE BASIN, UTAH Present Water Supply Area Water Required for Adequate Supply Present Supply Present Shortage 1,000 acres 1,000 A.- F+. 1,000 A.- Ft. 1,000 A.- Ft. 3.5 10.0 10.0 20.2 53.8 35.0 18.8 23.7 63.8 45.0 18.8 53.3 170.6 45.0 115.0 Present With Adequate Supply Adequate Inadequate Total irrigated Potential arable Per cent 100.0 65.11 70.51 26.4 lOften the effective supply is less than this because the shortage is concentrated in the latter part of the growing season. [ 122] |