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<br />WATER RESOURCES <br /> <br />o <br />o <br />w <br />Q:) <br /> <br />The Greater Sagers Wash Watershed is made up of three smaller watersheds, Sagers Wash, <br />Nash Wash, and Pinto Wash. The Sagers Wash watershed is the most westerly drainage and <br />includes Sagers Flat and "The Highlands". Sagers Wash is an ephemeral stream that drains an <br />area of approximately 71 ,389 acres. The Nash Wash watershed is the most easterly drainage <br />and includes the largest portion of the Book Cliffs found in the Greater Sagers Wash Watershed. <br />Nash Wash is an intermittent stream that drains an area of approximately 47,798 acres. <br />The Pinto Wash watershed is located between the Sagers Wash and Nash Wash watersheds and <br />is made up almost entirely of gently rolling lowlands, Pinto Wash is an intermittent stream that <br />drains an area of approximately 34,013 acres. All three watersheds are characterized by a <br />distinct dendritic drainage pattern with a high density of rills and gullys. Many gullies have a <br />depth greater than fifteen feet. <br /> <br />Watershed relief is approximately 4900 feet with 3800 feet of elevation change occurring within <br />the first twelve miles of the head of the watershed as a result of the steep escarpment of the <br />Book Cliffs. The remaining twenty miles of the watershed is characterized by more gently <br />rolling terrain. <br /> <br />A very large percentage of the daily precipitation events produce storms of a tenth of an inch <br />or less. At Thompson, Utah, five miles west of the Greater Sagers Wash Watershed, during a <br />forty year period, over 93 % of the 13,824 daily rainfall totals were 0.10 inches or less. This <br />includes days with no precipitation. In the southern portion of the Greater Sagers Wash <br />Watershed at Cisco, nearly the identical percentage of daily totals were O. 10 inches or less <br />(Figures A-I 1.0 and A-12.0). Clearly, most rainstorms in the Greater Sagers Wash region are <br />of insufficient size to produce runoff. <br /> <br />The greatest percentage of precipitation occurs as high intensity, short duration convective <br />thunder storms during August, September, and October. Pluvial indices, or rainfall intensity, <br />and frequency data for the Greater Sagers Wash Watershed are found in Table 3.0. The runoff <br />from these high intensity, short duration storms is responsible for moving most of the sediment <br />and salt out of the watershed. Estimated runoff volume for an average 100 acre subbasin can be <br />found in Table 4.0. <br /> <br />The present hydrologic condition of the Greater Sagers Wash Watershed is characterized by <br />sparse vegetative cover, unstable soils, low infiltration rates, and a high drainage density. These <br />conditions result in a high percentage of the annual precipitation occurring as surface runoff, <br />short times of concentration, high peak flows, high rates of rill and gully formation, mass <br />wasting of stream banks, and a resulting high rate of erosion and sedimentation. <br /> <br />SURFACE WATER <br /> <br />Surface water quality is poor with large volumes of sediment and salts being transported during <br />infrequent peak flows. <br /> <br />26 <br />