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Show OCCURRENCE OF UNDERGROUND WATER. 45 irrigation and domestic purposes, under water rights owned by farmers. In order for Salt Lake City to utilize these streams it must buy the water rights or exchange with the farmers an equivalent amount of water obtained either from Utah Lake or from pumping plants. The present public supply accordingly is obtained from City, Parleys, and Emigration creeks. The watershed of City Creek is protected from forest fires and from contamination, and many of its springs are developed. The flow is distributed from settling tanks near the mouth of the canyon and from a reservoir on Capitol Hill having a capacity of approximately 1,000,000 gallons. The surplus waters of City Creek are allowed to escape through flood ditches. Water from Parleys Crpek to the extent of 81.8 per cent of its flow has been obtained by Salt Lake City in exchange for an equivalent amount of water from Utah Lake delivered through the Jordan and Salt Lake City canal. A settling reservoir, holding somewhat less than 1,000,000 gallons has been constructed at the mouth of Parleys Canyon, whence the water is conducted through a concrete conduit to a storage reservoir with a capacity of about 5,000,000 gallons situated on Thirteenth East street. An additional supply is obtained from a trench in the bed of Emigration Creek half a mile above the mouth of the canyon. This trench is approximately 150 feet long, 10 feet wide, and 18 feet deep. It was dug in sand and gravel in the bed of the creek and at right angles to its course. A supply estimated to amount to 1,000,000 gallons a day is thus obtained, which is piped to the Thirteenth East street reservoir. No direct record is kept of the amount of water used by Salt Lake City, but discharge measurements of the creeks at the mouths of the canyons show the amount available. This is insufficient during the dry months and the use of water is restricted to a per capita consumption of 120 gallons a day, although it is considered desirable, in this dry climate, where lawns and gardens have to be irrigated, to maintain a per capita supply of approximately 300 gallons a day. It is planned to obtain in the immediate future a portion of the flow of Big Cottonwood Creek, by exchanging therefor water from Jordan River, delivered through the City canal, as is being done in the case of Parleys Creek, and to make the new supply available by constructing a pipe line from the mouth of Big Cottonwood Canyon to the mouth of Parleys Canyon, a distance of about 7 miles. SOUTH OF SALT LAKE CITY. Lowland area.- It will be convenient to divide the area south of Salt Lake City into a lowland and an upland portion, taking as the dividing line that which separates flowing and nonflowing wells. PI. VIII shows that this line extends contiguous to, but below, the Jordan and Salt Lake City canal as far as Little Cottonwood Creek, after crossing which it turns westward to the flood plain of Jordan River. The lowland area is traversed by Parleys, Mill, Big Cottonwood, and Little Cottonwood creeks, which flow in open valleys, with broad and low intervening divides. The general aspect of the country is that of a slightly dissected plain that rises gently toward the upland terraces. This area is relatively thickly populated, and intensive farming is widely practiced. The detailed character of the underlying lake sediments is not satisfactorily knowTn, but from the well records conditions appear to be similar to those found elsewhere in the area under consideration. Beneath the lowlands the stratigraphy is more uniform than nearer the base of the mountains; fine- textured sediments are more abundant than coarse, and clay predominates. But a comparison of available well records fails to establish a correlation between the different beds of sand and gravel throughout the lowland. Well drivers state that all logs are different, and yet that, on the whole, general sections persist for certain areas in which the differences are minor. It is believld that the sediments slope toward Jordan River at about the same angle as does the surface. The best- defined sequence that has been reported occurs immediately south of Salt Lake City, where in general light- colored clay at the surface overlies blue clay ranging from 30 to 70 feet in thickness, beneath which water- bearing sands and gravels occur at a depth of about 100 |
