By Lori E. Apodaca, Nancy E. Driver, Verlin C. Stephens, and Norman E. Spahr

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 95–4263, 33 p.

This document also is available in LizardTech DjVu format: WRIR 95–4263.djvu (894 KB)

Abstract

The Upper Colorado River Basin in Colorado and Utah is 1 of 60 study units selected for water-quality assessment as part of the U.S. Geological Survey's National Water-Quality Assessment program, which began full implementation in 1991. Understanding the environmental setting of the Upper Colorado River Basin study unit is important in evaluating water-quality issues in the basin. Natural and human factors that affect water quality in the basin are presented, including an overview of the physiography, climatic conditions, general geology and soils, ecoregions, population, land use, water management and use, hydrologic characteristics, and to the extent possible aquatic biology. These factors have substantial implications on water-quality conditions in the basin. For example, high concentrations of dissolved solids and selenium are present in the natural background water conditions of surface and ground water in parts of the basin. In addition, mining, urban, and agricultural land and water uses result in the presence of certain constituents in the surface and ground water of the basin that can detrimentally affect water quality. The envi- ronmental setting of the study unit provides a framework of the basin characteristics, which is important in the design of integrated studies of surface water, ground water, and biology.

Abstract

Introduction

Purpose and scope

Acknowledgments

Environmental setting

Physiography

Climate

General geology

General soils

Ecoregions

Population

Land use

Water management

Water use

Hydrologic characteristics

Surface water

Annual and monthly flow characteristics

Floods and droughts

Human effects on streamflow

Ground water

Unconsolidated aquifers

Bedrock aquifers

Water movement

Stream-aquifer relations

Aquatic biological characteristics

Implications of environmental setting on water quality

Natural factors

Human factors

Summary

References cited

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