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<br />~( . ~- -> j' <br /> <br />Descriotlon of Recommended Plan: <br /> <br />The recommended plan is composed of management and enduring conservation practices which <br />would reduce. deep percolation, runoff and irrigation induced erosion thereby, improving water quality <br />to both surface and groundwater, the Arkansas River,as well as to protecting the resource base. <br /> <br />Project Setting <br /> <br />Location and Size <br /> <br />The Highline Breaks Creeks Watershed is located in eastern Pueblo and Otero counties in <br />southeastern Colorado. The watershed consists of 89,650 acres and averages 4 to 5 miles wide and <br />35 miles long. La Junta, Colorado is on the east edge and Boone is near the western edge of the <br />watershed. Pueblo, Colorado is 20 miles west of the watershed area. <br /> <br />The watershed is bounded on the west by the Highline Canal Diversion, on the south by the Highline <br />Canal, on the east by the King Arroyo, and on the North by the Arkansas River. It includes the outlet <br />area of the Apishapa River, Chicosa, and Timpas Creeks, Crooked and Smith Arroyos, and the <br />Patterson Hollow, all outlet into the Arkansas River. <br /> <br />Geolo.av and Phvsloaraohic Descrlotlon <br /> <br />Highline Breaks watershed is located within the Colorado Piedmont section of the Great Plains <br />Physiographic Province (Fenneman, 1931). The Colorado Piedmont represents an old erosion <br />surface. It isa mature to old, broadly rolling, elevated plain with local scarps. <br /> <br />Bedrock consists primarily of Cretaceous marine shales and limestones. These formations dip <br />slightly to the northwest, toward the Denver structural basin. The oldest formation that crops out in <br />the watershed is the Upper Cretaceous Carlile shale, which is found south of the Arkansas River at <br />La Junta. Overlying the Carlile Shale (from oldest to youngest) is the Fort Hays limestone and <br />Smoky Hill shale members of the Niobrara Formation, and the Pierre shale. <br /> <br />Shales and limestones have higher concentration of some minerals than other rock types have. This <br />is particularly true of minerals such as sulfur and trace minerals such as arsenic, boron, and selenium <br />(Turekina and Wedepohl, 1961). <br /> <br />Studies by Schultz and others (1980) also showed elevated sulfur and trace mineral concentrations <br />in studies done of the Upper Cretaceous Pierre shale and equivalent formations. The sediment <br />source areas for these formations was to the west. The watershed area is far from the source area, <br />so sediments are almost exclusively fine grained marine shale and muddy limestone. <br /> <br />3 <br />