| OCR Text |
Show is extremely low and the inflow to the bay greatly reduced, the bay may even become isolated and tend to stagnate. North Juab Valley The smaller front streams entering Worth Juab Valley are of excellent quality for most uses except for Salt Creek, the largest stream, which has a TDS ranging from kOO to TOO mg/ 1 and is sodium chloride- carbonate- type water due to contact with Arapie shales in its drainage area. Nephi City's municipal and industrial needs are met by exchange for higher quality water from springs in the canyon. Sevier River The quality of the water in the Sevier River varies in concentration of dissolved solids from 290 to 3,000 mg/ l from Piute Reservoir to the Lower Sevier area. At Piute Reservoir the water is of the calcium bicarbonate- type with an average concentration of dissolved solids of about 290 mg/ 1. Near Richfield the concentration of dissolved solids is between 500 and 600 mg/ 1. Between Richfield and Sevier Bridge Reservoir groundwater inflow contributes large quantities of salts to the streamflow. The quality of water at Lynndyl below Sevier Bridge Reservoir ranges from 1,500 to 1,750 mg/ 1 and has sodium chloride, bicarbonate, and sulfate as the primary constituents. Below Delta the salt concentration of the water in the Sevier River reaches in excess of 3,000 mg/ 1. Even with the high concentrations of salts in the Sevier River water, when the water is available, the lands that it is applied to are quite productive. Uinta Basin The Uinta Basin mountain front streams affected by the Bonneville Unit are high quality water, primarily of the calcium bicarbonate- type with TDS ranging from 30 to 350 mg/ 1 measured above most irrigated land. The historic and present modified^' flow and quality of water data for Duchesne River near Randlett, Utah; Green River near Ouray, Utah; and Colorado River below Hoover Dam, Arizona - Nevada are shown in Tables B- 9, B- 10, and B- ll. These data, which show the effect of present water use on downstream water quality, were extracted from Colorado River Basin Progress Report No. k. ^ It will be noted that although the salinity concentration of the present modified situation is about 5 percent higher than the historic situation, the TDS in tons under present modified conditions is less than 1 percent above historic conditions. The increase in salinity concentration is therefore due primarily to decreased flows caused by greater consumptive use of water in the basin. 1/ The present modified condition is that expected at any point with all existing upstream projects in operation for the full period of study. |
