Ground water in the Jordan Valley, Utah

Abstract

The Jordan Valley is a small part of a larger area that during the glacial epoch was covered by an ancient lake known as Lake Bonneville. The Jordan River, the natural drainage path from Utah Lake, flows northward through the center of the valley and empties into Great Salt Lake. The Jordan Valley is a rockbottomed valley in which a great thickness of clay, silt, sand, and gravel has been laid down irregularly. The thickness of this material is not definitely known, but wells in the valley have penetrated as much as 2,000 feet without encountering bedrock. These sediments are chiefly stream and lake deposits. The material at the surface of the valley was deposited in an ancient lake which at its highest stage stood about 1,000 feet above the level of Great Salt Lake. The shore deposits laid down in this lake occur in the form of terraces or benches around the margin of this basin. The two most prominent benches are known as the Bonneville and Provo benches. The Bonneville bench was formed during the highest stage of the lake, and the Provo bench during a later stage about 400 feet lower. Ground water occurs in the valley as (1) shallow ground water overlying the confining layer creating the artesian basin, (2) local perched water bodies, and (3) an artesian basin or reservoir including the recharge area. It occurs chiefly in the pore spaces of the sand and gravel of the stream and lake deposits. The most permeable water-bearing material occurs near the foot of the Wasatch Mountains in the area occupied by the Provo and Bonneville benches. At some distance from the mountains beds of finer material dense silt and clay alternate with more permeable beds of sand and gravel, giving rise to artesian conditions. On the Provo and Bonneville benches the water levels lie at considerable distances below the surface; but in the lower areas along the Jordan River and west of Salt Lake City as far as the lake, artesian conditions exist and many flowing wells have been drilled. The principal sources of ground water in the Jordan Valley are the water that seeps into the ground from the streams entering the valley, the water that penetrates directly from the ram and snow that fall upon the bench lands on the east side of the valley, and the water that percolates downward from irrigation canals and from irrigated lands, chiefly derived from Utah Lake. In addition some deep-seated thermal water rises along the Wasatch fault. Field determinations of the chloride content of the ground water show that nearly all the waters from the main part of the area of artesian flow, extending from Salt Lake City to Murray have a chloride content of less than 100 parts per million, and most of them have less than 50 parts per million. The distribution of waters of different chloride content indicates that the water of the main part of the area of artesian flow is derived chiefly from supplies that contain only small amounts of chloride namely, seepage from the streams that head in the Wasatch Mountains and rain and snow that fall upon the Provo and Bonneville benches and penetrate downward through the permeable materials that underlie these benches