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<br />- 6 - <br /> <br />80ils.- The soils in the upper watershed area above the main <br />canal are variable but are mostly derived from shale and are heavy <br />textured. In the less steeper areas, soils are moderately deep but <br />still show a strong influence from shale parent material. In other <br />places, shallow shale-derived soils alternate with numerous shale <br />outcrops. <br /> <br />Below the main canal, the soils are moderately heavy to heavy <br />with slow infiltration and moderately high susceptibility to water <br />erosion when not protected by vegetation. Soils over shale are <br />subject to salt accumulation in natural depressions if irrigation <br />water is allowed to accumulate. In a few places a medium-textured <br />shallow soil occurs over sandstone. In other places, mostly on <br />ridge or meSa tops, medium-textured soils are developed on wind- <br />deposited materials, which are often underlain by sand and gravel <br />alluvial outwash. <br /> <br />Range Sites.- The upper watershed area consists of steep <br />mountain slopes and clayey and shaley foothills range sites. The <br />mountain slopes support a fair growth of ponderosa pine in a few <br />areas but are mostly covered with dense thickets of gambel oak or <br />scattered clumps of pinon and juniper. This site generally has a <br />fair to good understory of forage grasses, forbs, and shrubs, and <br />is open to grazing, but is so steep and rough that it has limited <br />value as rangeland. The most desirable use of this area is <br />limited range for game animals. <br /> <br />The cover on the foothills site includes about 25 percent <br />brush and trees, mainly pinon, juniper, and sagebrush. Grass <br />cover, which dominates, includes such native species as western <br />wheatgrass, needle and thread, June grass, gaIleta, and blue grama. <br />Most of the area is presently in poor condition, with big sage- <br />brush, pinon, juniper, cheatgrass, and a stunted growth of blue <br />grama comprising the cover. <br /> <br />Most of the soils in the upper watershed area are heavy <br />textured. The soils, the steep topography, and fair to poor cover <br />all contribute to the high runoff and sediment production of the <br />watershed. <br />