| OCR Text |
Show Groundwater also supplies some of the agricultural needs for irrigation and livestock. Groundwater is encountered in different aquifer systems. The confined or artesian aquifers in the valley fill supply water to nearly all of the wells in existence. Shallow unconfined aquifers contain the largest portion of the water in storage but yield only small quantities of water to wells. Some groundwater has also been found in bedrock aquifers and a few wells finished in highly fractured bedrock have been quite productive. However, these aquifers generally have been relatively unproductive, yielding smaller amounts of poorer quality water. The ability of the aquifers to yield water to wells varies considerably throughout the areas where groundwater has been developed. The aquifers tend to be much more productive where the sediments are coarse such as the gravel in the alluvial fans and deltas near the mountain fronts. The high- yield wells are generally found in these regions. The sediments encountered in the central portions of the valleys are generally much finer- grained. The yield from these fine- grained artesian aquifers is generally much less than from the same aquifers closer to the mountain fronts. In fact, numerous wells finished in the finegrained aquifers yield just enough water to supply the domestic needs for one or two families. There is considerable variation in quality of the presently developed groundwater. In regions where recharge is most plentiful, especially where streams enter the valleys along the Wasatch Front, the groundwater is suitable for most uses. The chemical quality of groundwater in regions of high recharge is generally less than 500 mg/ l of dissolved solids. In other areas where recharge is not as plentiful, such as the west side of Jordan Valley, the salinity may be greater than 2,000 mg/ l. Groundwater from confined or artesian aquifers is generally high quality, whereas water from the shallow unconfined aquifer is usually not suitable for most uses because of its poor chemical and bacteriological quality. b. Surface Water ( l) Present Supply and Use ( a) Jordan Valley Present available surface water supplies in the Jordan Valley or Salt Lake County area of the proposed Bonneville Unit include the Wasatch Front streams within Salt Lake County, the Jordan River and Utah Lake, and imported water from the Provo River Project. 173 |
