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Show In addition to the hot pots, at least 7 thermal springs in the area flow perennially. The discharge of these springs ranges from a few gallons per minute to about 3 cfs; the total discharge of the 7 springs in 1967 was about 7 cfs. The water temperature of the 7 flowing springs ranges from 30° to 46° C ( 86°- 144° F). Chemical quality Nearly all the nonthermal water from the consolidated rocks is suitable for domestic use according to the standards of the U. S. Public Health Service ( 1962); the exception is some water from the volcanic rocks that is high in iron. All the water is hard to very hard, and many residents of the area use ion- exchange type softeners in their domestic water systems. Water from the hot pots is too mineralized to be desirable for domestic use, and plentiful supplies of better water are available from the springs that furnish the public supply of Midway. Even water from the hot pots is used by livestock; and, according to the criteria established by the U. S. Department of Agriculture ( U. S. Salinity Lab. Staff, 1954), all water from the consolidated rocks in the area is suitable to use for irrigation. Although water from the hot pots is in the high salinity hazard class for irrigation, it can be used for salt- tolerant crops on the premeable and well- drained soils in Heber Valley. Samples of water for chemical analysis were collected from 28 springs, wells, and tunnels that tap the consolidated rocks; the analyses are included in table 5. The locations from which the samples were collected and diagrammatic representations of the concentrations of the principal dissolved solids in some of the samples are shown on plate 3. Four kinds of water can be distinguished from four general sources in the consolidated rocks. Figure 9 illustrates average analyses of samples of the four kinds of water. Water from the sandstones and limestones of Jurassic age and older is represented by diagram 1 ( fig. 9). The water is of calcium magnesium bicarbonate type and is not highly mineralized; the concentration of dissolved solids in 13 samples from these formations ranged from 104 to 488 mg/ l. Most samples were hard according to the classification of the U. S. Geological Survey ( more than 120 mg/ l hardness), and many samples were in the very hard range ( more than 180 mg/ l). The concentration of silica was low; the samples ranged from 8.2 to 25 mg/ l, but most were below 20 mg/ l. The percentages of sulfate and chloride were low ( each less than 20 percent of the total anions), and chloride was generally slightly lower than sulfate. Diagram 2 ( fig. 9) is typical of water from the shales of Triassic age; 1 sample was collected from a spring, 1 from a well, and 3 from mine drain tunnels. The water is of calcium sulfate type, and generally more concentrated than that from the limestones and sandstones. The concentration of dissolved solids in 5 samples ranged from 218 to 691 mg/ l. All samples were in the very hard range; the hardness of 2 samples exceeded 300 mg/ l. Concentrations of silica ranged from 6.3 to 21 mg/ l. V Water from the volcanic rocks is represented by diagram 3 ( fig. 9). The volcanic rocks yield calcium bicarbonate type water; the concentrations of 5 samples ranged from 249 to 1,020 mg/ l. Four samples were in the very hard range, but water from the volcanic rocks was generally softer than water from the shales. Concentrations of silica were much higher in these samples than in water from other sources in the area. The silica concentration ranged from 22 to 52 mg/ l, but only 1 sample was below 30 mg/ l. The relative concentrations of sulfate and chloride in these waters was also distinctive; the samples contained from 3 to 5 times as much chloride as sulfate. The volcanic rocks are the only consolidated rocks in the area that yield water containing 23 |
