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<br />1, Introduction
<br />
<br />This report documents the results of a fluvial geomorphologic assessment of an II-mile
<br />reach of the Upper Arkansas River near Leadville, Colorado, The project reach is a
<br />degraded segment of the Arkansas River that was delineated cooperatively by the
<br />Environmental Protection Agency (EPA) and the Upper Arkansas River Restoration
<br />Project (UARRP) Core Group, The reach includes Operable Unit II of the California
<br />Gulch Superfund Site as well as an additional eight miles of channel. This report was
<br />prepared by Inter-Fluve, Inc, for URS Operating Services, Inc, (URS), who was
<br />requested by the EP A to support the geomorphic evaluation,
<br />
<br />1.1. Project Location
<br />
<br />The study area is located in the Upper Arkansas River basin, Lake County, Colorado,
<br />near the city of Leadville (Figure 1.1), The basin is flanked by the Mosquito Range to
<br />the east and the Sawatch Range to the west The project reach consists of II-miles of the
<br />Upper Arkansas River channel and adjacent floodplain, beginning at the mouth of
<br />California Gulch and extending downstream to the mouth of Box Creek near Balltown
<br />(Figure 1,2), California Gulch enters the Arkansas River just west of Leadville.
<br />Tributaries that enter the Arkansas River project reach include Lake Fork Creek, Iowa
<br />Gulch, Thompson Gulch, Empire Gulch, Dry Union Gulch, Big Union Creek, Spring
<br />Creek, Sawmill Gulch, Box Creek, and Twobit Gulch, The elevation of the project area
<br />ranges from 9,150 to 9,500 feet above sea level.
<br />
<br />1.2. Report Organization
<br />
<br />This document is organized into 12 chapters and two technical appendices, The chapters
<br />included are as follows:
<br />
<br />I, Introduction,
<br />
<br />2, Project background, including the identified goals and objectives of the Upper
<br />Arkansas River Restoration Project (UARRP), the purpose of this investigation, and
<br />the procedures utilized in the evaluation,
<br />
<br />3, A summary of human impacts that have influenced geomorphic processes within the
<br />project reach,
<br />
<br />4. A description of general physical characteristics of the Upper Arkansas River Basin,
<br />including project subreaches,
<br />
<br />5, A description of the sedimentology of the project reach,
<br />
<br />6, An assessment of the geomorphic evolution of the project reach since the onset of
<br />mining activities, including the effects of human impacts on channel dynamics,
<br />
<br />7, An analysis of the hydrologic, hydraulic and sediment transport characteristics of the
<br />project reach, including the determination of subreach bankfull discharges, the range
<br />
<br />May 7, 1999
<br />
<br />Fluvial Geomorphological Assessment
<br />Upper Arkansas River
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<br />Page I
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