WSP02347

• File Number: 8102
• Description: Arkansas River Basin Basic Hydrology
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 5/7/1999
• Author: Inter-Fluve Inc
• Title: Fluvial Geomorphic Assessment of Upper Arkansas River - Final Report
• Water Supply Pro - Doc Type: Report/Study

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1. Introduction

This report documents the results of a fluvial geomorphologic assessment of an II-mile
reach of the Upper Arkansas River near Leadville, Colorado. The project reach is a
degraded segment of the Arkansas River that was delineated cooperatively by the
Environmental Protection Agency (EP A) and the Upper Arkansas River Restoration
Project (UARRP) Core Group. The reach includes Operable Unit II of the California
Gulch Superfund Site as well as an additional eight miles of channel. This report was
prepared by Inter-Fluve, Inc. for URS Operating Services, Inc. (URS), who was
requested by the EP A to support the geomorphic evaluation.

1.1. Project Location
The study area is located in the Upper Arkansas River basin, Lake County, Colorado,
near the city of Leadville (Figure 1.1). The basin is flanked by the Mosquito Range to
the east and the Sawatch Range to the west. The project reach consists of II-miles of the
Upper Arkansas River channel and adjacent floodplain, beginning at the mouth of
California Gulch and extending downstream to the mouth of Box Creek near Balltown
(Figure 1.2). California Gulch enters the Arkansas River just west of Leadville.
Tributaries that enter the Arkansas River project reach include Lake Fork Creek, Iowa
Gulch, Thompson Gulch, Empire Gulch, Dry Union Gulch, Big Union Creek, Spring
Creek, Sawmill Gulch, Box Creek, and Twobit Gulch. The elevation of the project area
ranges from 9,150 to 9,500 feet above sea level.

1.2. Report Organization

This document is organized into 12 chapters and two technical appendices. The chapters
included are as follows:

1. Introduction.

2. Project background, including the identified goals and objectives of the Upper
Arkansas River Restoration Project (UARRP), the purpose of this investigation, and
the procedures utilized in the evaluation.

3. A summary of human impacts that have influenced geomorphic processes within the
project reach.

4. A description of general physical characteristics of the Upper Arkansas River Basin,
including project subreaches.

5. A description of the sedimentology of the project reach.

6. An assessment of the geomorphic evolution of the project reach since the onset of
mining activities, including the effects of human impacts on channel dynamics.

7, An analysis of the hydrologic, hydraulic and sediment transport characteristics of the
project reach, including the determination of subreach bankfull discharges, the range

May 7, 1999

Fluvial Geomorphological Assessment
Upper Arkansas River

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