USGS - Science for a Changing World

U.S. GEOLOGICAL SURVEY

Scientific Investigations Report 2004-5143

Evaluation of Metal Loading to Streams near Creede, Colorado, August and September 2000

By B.A. Kimball, R.L. Runkel, K. Walton-Day, and B.K. Stover

ONLINE ONLY

ABSTRACT

Decisions about remediation of mine drainage on the watershed scale require an understanding of metal contributions from all sources to be able to choose the best sites for remediation. A hydrologic framework to study metal loading in the Willow Creek watershed, a tributary to the Rio Grande River, was established by conducting a series of tracer-injection studies. Each study used the tracer-dilution method in conjunction with synoptic sampling to determine the spatial distribution of discharge and concentration. Discharge and concentration data were then used to develop mass-loading curves for the metals of interest. The discharge and load profiles (1) identify the principal sources of load to the streams; (2) demonstrate the scale of unsampled, dispersed subsurface inflows; and (3) estimate the amount of natural attenuation. The greatest source of metal loads was from the Nelson Tunnel on West Willow Creek, which contributed 158 kilograms per day of zinc to the stream. Additional loading from other dispersed, subsurface inflows along West Willow Creek added substantial loads, but these were small in comparison to the loads from the Nelson Tunnel. No significant contributions of metal load from potential sources occurred along East Willow Creek. The lack of measurable loading may be a result of previous remedial actions along that stream. The lower Willow Creek section had relatively small contributions of load compared to what had been contributed upstream. This watershed approach provides a detailed snapshot of metal load for the watershed to support remediation decisions and quantifies processes that affect metal transport.

This report is contained in the following file:

SIR2004_5143.pdf (1.8 mb)

The file is readable with Adobe Acrobat Reader. The reader is available for free download from Adobe Systems Incorporated.

CONTENTS

Abstract

Introduction

Purpose and Scope

Methods

Approach

Tracer Injections and Stream Discharge

Synoptic Sampling and Analytical Methods

Mass-Loading Analysis

Principal Components Analysis

Evaluation of Metal Loading

West Willow Creek

Discharge

Chemical Characterization of Synoptic Samples

Load Profiles

Principal Locations of Mass Loading

Unsampled Inflow

Attenuation of Load

East Willow Creek

Discharge

Chemical Characterization of Synoptic Samples

Load Profiles

Principal Locations of Mass Loading

Unsampled Inflow

Attenuation of Metals

Lower Willow Creek

Discharge

Chemical Characterization of Synoptic Samples

Load Profiles

Summary—Implications for Remediation

References Cited

Appendix—Results of Chemical Analyses for Synoptic Samples Collected near Creede, Colorado


Send questions or comments about this report to the author, Briant Kimball at bkimball@usgs.gov, 801.908.5066.

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