Relations of Benthic Macroinvertebrates to 

Concentrations of Trace Elements in Water, 

Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions 

in Nonmining and Mining Areas of the Upper 

Colorado River Basin, Colorado, 1995–98

By Scott V. Mize and Jeffrey R. Deacon

Denver, Colorado

2002

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 02–4139
District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046

For additional information write to:

District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of firm, trade, and brand names in the report is for identification purposes only and does 

not constitute endorsement by the U.S. Geological Survey.

Copies of this report can be purchased 

from:

U.S. Geological Survey

Information Services

Box 25286

Denver Federal Center

Denver, CO 80225
Robert M. Hirsch

Associate Director for Water

FOREWORD

The U.S. Geological Survey (USGS) is committed 

to serve the Nation with accurate and timely scientific 

information that helps enhance and protect the overall 

quality of life, and facilitates effective management of 

water, biological, energy, and mineral resources. Information on the quality of the Nation’s water resources 

is of critical interest to the USGS because it is so integrally linked to the long-term availability of water that 

is clean and safe for drinking and recreation and that is 

suitable for industry, irrigation, and habitat for fish and 

wildlife. Escalating population growth and increasing 

demands for the multiple water uses make water availability, now measured in terms of quantity and quality, 

even more critical to the long-term sustainability of 

our communities and ecosystems.

The USGS implemented the National WaterQuality Assessment (NAWQA) Program to support 

national, regional, and local information needs and 

decisions related to water-quality management and 

policy. Shaped by and coordinated with ongoing 

efforts of other Federal, State, and local agencies, the 

NAWQA Program is designed to answer: What is the 

condition of our Nation’s streams and ground water? 

How are the conditions changing over time? How do 

natural features and human activities affect the quality 

of streams and ground water, and where are those 

effects most pronounced? By combining information 

on water chemistry, physical characteristics, stream 

habitat, and aquatic life, the NAWQA Program aims to 

provide science-based insights for current and emerging water issues. NAWQA results can contribute to 

informed decisions that result in practical and effective 

water-resource management and strategies that protect 

and restore water quality.

Since 1991, the NAWQA Program has implemented interdisciplinary assessments in more than 50 

of the Nation’s most important river basins and aquifers, referred to as Study Units. Collectively, these 

Study Units account for more than 60 percent of the 

overall water use and population served by public 

water supply, and are representative of the Nation’s 

major hydrologic landscapes, priority ecological 

resources, and agricultural, urban, and natural sources 

of contamination. 

Each assessment is guided by a nationally consistent study design and methods of sampling and analysis. The assessments thereby build local knowledge 

about water-quality issues and trends in a particular 

stream or aquifer while providing an understanding of 

how and why water quality varies regionally and 

nationally. The consistent, multiscale approach helps 

to determine if certain types of water-quality issues are 

isolated or pervasive and allows direct comparisons of 

how human activities and natural processes affect 

water quality and ecological health in the Nation’s 

diverse geographic and environmental settings. Comprehensive assessments on pesticides, nutrients, volatile organic compounds, trace metals, and aquatic 

ecology are developed at the national scale through 

comparative analysis of the Study-Unit findings. 

The USGS places high value on the communication and dissemination of credible, timely, and relevant 

science so that the most recent and available knowledge about water resources can be applied in management and policy decisions. We hope this NAWQA 

publication will provide you the needed insights and 

information to meet your needs, and thereby foster 

increased awareness and involvement in the protection 

and restoration of our Nation’s waters. 

The NAWQA Program recognizes that a national 

assessment by a single program cannot address all 

water-resource issues of interest. External coordination at all levels is critical for a fully integrated understanding of watersheds and for cost-effective 

management, regulation, and conservation of our 

Nation’s water resources. The Program, therefore, 

depends extensively on the advice, cooperation, and 

information from other Federal, State, interstate, 

Tribal, and local agencies, nongovernment organizations, industry, academia, and other stakeholder 

groups. The assistance and suggestions of all are 

greatly appreciated.

FOREWORD III
CONTENTS V

Foreword ................................................................................................................................................................................ III

Abstract.................................................................................................................................................................................. 1

Introduction............................................................................................................................................................................ 2 

Purpose and Scope....................................................................................................................................................... 4

Previous Work.............................................................................................................................................................. 4

Description of Study Area ........................................................................................................................................... 4

Geology.............................................................................................................................................................. 6

Climate............................................................................................................................................................... 6

Land Use/Land Cover........................................................................................................................................ 7

Acknowledgments ....................................................................................................................................................... 8

Data Collection and Analysis ................................................................................................................................................ 8

Site Selection ............................................................................................................................................................... 8

Sample Collection........................................................................................................................................................ 8

Data Analysis............................................................................................................................................................... 10

Quality-Assessment Procedures .................................................................................................................................. 11

Water-Column Samples and Physical Water-Quality Parameters ......................................................................................... 12

Concentrations and Distribution of Selected Trace Elements .............................................................................................. 13

Water Column .............................................................................................................................................................. 13

Streambed Sediment .................................................................................................................................................... 17

Transplanted Bryophytes ............................................................................................................................................. 20

Relation among Selected Trace Elements in the Water Column, Streambed Sediment, and Transplanted 

Bryophytes............................................................................................................................................................... 21

Stream Habitat Characteristics .............................................................................................................................................. 25

Benthic Macroinvertebrate Community Structure................................................................................................................. 25

Ephemeroptera (mayflies) ........................................................................................................................................... 31

Plecoptera (stoneflies) ................................................................................................................................................. 31

Trichoptera (caddisflies) .............................................................................................................................................. 33

Chironomidae (midges) ............................................................................................................................................... 35

Natural and Human-Related Factors............................................................................................................................ 35

Comparison of Water Quality to Biological Conditions........................................................................................................ 36

Summary and Conclusions .................................................................................................................................................... 37

References Cited.................................................................................................................................................................... 39

Appendixes ............................................................................................................................................................................ 43

Appendix A: Surface-water-quality field measurement constituents and minimum reporting levels for samples

collected from selected sites in the study area......................................................................................................... 45

Appendix B: Streambed-sediment constituents and minimum reporting levels for samples collected from 

selected sites in the study area................................................................................................................................. 46

Appendix C: Transplanted bryophyte constituents and minimum reported levels for samples collected from 

selected sites in the study area................................................................................................................................. 47

Appendix D: Selected water-column data for samples collected from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1997–98................................................................................................... 48

Appendix E: Streambed-sediment data for samples collected from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1995–96................................................................................................... 50

Appendix F: Transplanted bryophyte data from samples collected from nonmining and mining sites in the

Upper Colorado River Basin, Colorado, 1997–98................................................................................................... 51

Appendix G: Taxa, densities, total number of macroinvertebrates, and sampling date for samples collected from

nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98 ........................................... 52

CONTENTS
VI CONTENTS

FIGURES

1. Map showing location and basin surficial geology of nonmining and mining sites in the Upper Colorado River

Basin, Colorado, 1995–98 ........................................................................................................................................ 3

2–12. Graphs showing:

2. Percentage of land use/land cover at nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1995–98............................................................................................................................................ 7

3. Selected physical and chemical water-column data for samples from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1997–98 ........................................................................................... 14

4. Concentrations of dissolved aluminum, arsenic, copper, iron, lead, and zinc in water-column samples from

nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98..................................... 15 

5. Concentrations of aluminum, arsenic, copper, iron, lead, and zinc in the less than 63-micrometer fraction 

of streambed-sediment samples from nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1995–96, with comparison to Canadian Council of Ministers of the Environment (CCME) 

probable effect level (PEL) sediment-quality guidelines .................................................................................. 19

6. Concentrations of aluminum, arsenic, copper, iron, lead, and zinc in transplanted bryophyte samples from

nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98, with comparison to 

initial concentrations of bryophyte source material from Nate Creek ditch, Colorado, 1997–98 .................... 22

7. Distributions of zinc concentrations in water-column, streambed-sediment, and transplanted bryophyte

samples from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1995–98.............. 24

8. Composition of predominant groups, taxa, and Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness 

of macroinvertebrates from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 

1997–98............................................................................................................................................................. 28

9. Ratio of specialist to generalist macroinvertebrate species with and without Simuliidae from nonmining 

and mining sites in the Upper Colorado River Basin, Colorado, 1997–98....................................................... 30

10. Abundance of selected mayfly and stonefly taxa from nonmining and mining sites in the Upper Colorado 

River Basin, Colorado, 1997–98 ....................................................................................................................... 32

11. Abundance and percentage of selected caddisfly and midge taxa from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1997–98 ............................................................................................ 34

12. Relation between water-quality scores (developed in this study) and biological condition scores and

biological condition categories for nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1997–98............................................................................................................................................ 36

TABLES

1. Description of sampling sites in the Upper Colorado River Basin, Colorado, 1995–98 ........................................ 5

2. Selected water-column data for samples from nonmining and mining sites in the Upper Colorado River Basin,

Colorado, 1997–98.................................................................................................................................................. 13

3. Comparison of acute and chronic aquatic-life standards established by the Colorado Department of Public 

Health and Environment (1999) and selected trace-element dissolved and total concentrations in watercolumn samples from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98....... 16

4. Mean concentrations and ranges of concentrations for selected trace elements in soils in the Western United 

States and streambed-sediment samples from nonmining and mining sites in the Upper Colorado River Basin,

Colorado, 1995–96.................................................................................................................................................. 18

5. Comparison of sediment-quality guidelines from Canadian Council of Ministers of the Environment (1999) 

and selected trace-element concentrations in streambed-sediment samples from nonmining and mining sites 

in the Upper Colorado River Basin, Colorado, 1995–96 ....................................................................................... 20

6. Comparison of selected trace-element concentrations in bryophyte (Hygrohypnum ochraceum) source material 

to trace-element concentrations in transplanted bryophytes from nonmining and mining sites in the Upper 

Colorado River Basin, Colorado, 1997–98 ............................................................................................................. 21

7. Bioconcentration factors (BCF15) for transplanted bryophytes (Hygrohypnum ochraceum) after 15-day 

exposure period to ambient conditions at nonmining and mining sites in the Upper Colorado River Basin,

Colorado, 1997–98.................................................................................................................................................. 23

8. Spearman rank correlations of selected trace-element concentrations in the water-column, streambedsediment, and transplanted bryophyte samples at nonmining and mining sites in the Upper Colorado River 

Basin, Colorado, 1995–98....................................................................................................................................... 23
CONTENTS VII

9. Classification ranking of U.S. Environmental Protection Agency’s Rapid Bioassessment Protocols habitat 

parameters for nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98 .................. 26

10. Habitat assessment results using U.S. Environmental Protection Agency’s Rapid Bioassessment Protocols 

for nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98..................................... 27

11. Selected biotic metrics from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 

1997–98 .................................................................................................................................................................. 29

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Temperature in degrees Celsius (C) may be converted to degrees Fahrenheit (F) as follows:

F=1.8 (C)+32

Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929—

a geodetic datum derived from a general adjustment of the first-order level nets of the United States 

and Canada, formerly called Sea Level Datum of 1929.

Altitude, as used in this report, refers to distance above or below sea level.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (S/cm at 

25°C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or 

micrograms per liter (g/L).

Concentrations of chemical constituents in streambed sediment and bryophytes are given in 

micrograms per gram (g/g).

ADDITIONAL ABBREVIATIONS

(%) percent

(Al) aluminum

(As) arsenic

(Cu) copper

(Fe) iron

(Pb) lead

(Zn) zinc

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch

millimeter (mm) 0.03937 inch

meter (m) 3.281 foot (ft)

inch 2.54 centimeter (cm)

inch 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.0929 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

Flow

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)
1

Relations of Benthic Macroinvertebrates to 

Concentrations of Trace Elements in Water, 

Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in 

Nonmining and Mining Areas of the Upper 

Colorado River Basin, Colorado, 1995–98

By Scott V. Mize and Jeffrey R. Deacon

Abstract

Intensive mining activity and highly mineralized rock formations have had significant 

impacts on surface-water and streambed-sediment 

quality and aquatic life within the upper reaches 

of the Uncompahgre River in western Colorado. 

A synoptic study by the U.S. Geological Survey 

National Water-Quality Assessment Program was 

completed in the upper Uncompahgre River Basin 

in 1998 to better understand the relations of trace 

elements (with emphasis on aluminum, arsenic, 

copper, iron, lead, and zinc concentrations) in 

water, streambed sediment, and aquatic life. 

Water-chemistry, streambed-sediment, and 

benthic macroinvertebrate samples were collected 

during low-flow conditions between October 

1995 and July 1998 at five sites on the upper 

Uncompahgre River, all downstream from historical mining, and at three sites in drainage basins 

of the Upper Colorado River where mining has 

not occurred. Aquatic bryophytes were transplanted to all sites for 15 days of exposure to the 

water column during which time field parameters 

were measured and chemical water-quality and 

benthic macroinvertebrate samples were 

collected. Stream habitat characteristics also were 

documented at each site.

Certain attributes of surface-water chemistry among streams were significantly different. 

Concentrations of total aluminum, copper, iron, 

lead, and zinc in the water column and concentrations of dissolved aluminum, copper, and zinc 

were significantly different between nonmining 

and mining sites. Some sites associated with 

mining exceeded Colorado acute aquatic-life 

standards for aluminum, copper, and zinc and 

exceeded Colorado chronic aquatic-life standards 

for aluminum, copper, iron, lead, and zinc. 

Concentrations of copper, lead, and zinc in 

streambed sediments were significantly different 

between nonmining and mining sites. Generally, 

concentrations of arsenic, copper, lead, and zinc 

in streambed sediments at mining sites exceeded 

the Canadian Sediment Quality Guidelines probable effect level (PEL), except at two mining sites 

where concentrations of copper and zinc were 

below the PEL. Concentrations of arsenic, copper, 

iron, and lead in transplanted bryophytes were 

significantly different between nonmining and 

mining sites. Bioconcentration factors calculated 

for 15-day exposure using one-half of the 

minimum reporting level were significantly 

different between nonmining and mining sites. In 

general, concentrations of trace elements in 

streambed sediment and transplanted bryophytes 

were more closely correlated than were the 

concentrations of trace elements in the water 

column with streambed sediments or concentrations in the water column with transplanted 

bryophytes.
2 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Stream habitat was rated as optimal to 

suboptimal using the U.S. Environmental Protection Agency Rapid Bioassessment Protocols for 

all sites in the study area. Generally, stream 

habitat conditions were similar at nonmining 

compared to mining sites and were suitable for 

diverse macroinvertebrate communities. All study 

sites had optimal instream habitat except two 

mining sites with suboptimal instream habitat 

because of disturbances in stream habitat.

The benthic macroinvertebrate community 

composition at nonmining sites and mining sites 

differed. Mining sites had significantly lower total 

abundance of macroinvertebrates, fewer numbers 

of taxa, and lower dominance of Ephemeroptera 

(mayflies), Plecoptera (stoneflies), and 

Trichoptera (caddisflies), and a larger percentage 

of tolerant species than did nonmining sites. The 

predominance of Baetis sp. (mayflies), Hydropsychidae (caddisflies), and large percentage of 

Orthocladiinae chironomids (midges) at mining 

sites indicated that these species may be tolerant 

to elevated trace-element concentrations. The 

absence of Heptageniidae (mayflies), Chloroperlidae (stoneflies), and Rhyacophila sp. (caddisflies) at mining sites indicated that these species 

may be sensitive to elevated trace-element 

concentrations. 

Comparison of field parameters and chemical water-quality characteristics to biological 

conditions was conducted using a water quality 

score (WQS) and a biological condition score 

(BCS). In general, as the WQS increased, the 

BCS also increased. Nonmining sites had higher 

WQS’s and BCS’s than mining sites. The BCS 

categorized the nonmining sites as nonimpaired, 

and the mining sites were categorized as slightly 

to severely impaired. Other important factors in 

this study that influenced surface-water quality 

include stream pH, chemical solubility of trace 

elements, stream temperature, stream elevation, 

organic inputs into the stream, basin geology, and 

stream habitat at a site. Although high concentrations of some trace elements may occur naturally, 

trace-element concentrations at mining sites were 

much higher. High trace-element concentrations 

appear to affect the macroinvertebrate communities more than the other factors at these sites. 

Mayfly, stonefly, and caddisfly abundance and the 

percentage of midge species are good indicators 

of mining effects at sites in the study area.

INTRODUCTION

The National Water-Quality Assessment 

(NAWQA) Program is a long-term program of the 

U.S. Geological Survey (USGS) designed to describe 

the status and trends in the quality of the Nation’s 

surface- and ground-water resources and to provide an 

understanding of the natural and human factors that 

can affect the quality of these resources (Leahy and 

others, 1990). The program is interdisciplinary and 

integrates biological, chemical, and physical data to 

assess the Nation’s water quality at local, regional, and 

national levels. The NAWQA Program is designed to 

use multiple lines of evidence to assess water quality. 

Using several types of media to assess the water 

quality provides integrated information that is a more 

complete description of the water quality than is 

possible with just one sampling medium.

Benthic macroinvertebrate-community surveys 

are one of the few means of directly assessing the 

biological integrity of a site and represent a group of 

aquatic organisms that are sensitive to changes in 

water chemistry and physical habitat (Meador and 

Gurtz, 1994). The water quality of stream reaches can 

be characterized by evaluating the results of qualitative 

and quantitative measurements of the benthic macroinvertebrate community. The macroinvertebrate 

component of NAWQA biological community surveys 

is designed primarily to characterize the distribution 

and community structure of benthic macroinvertebrate 

species and their relation to water and streambed-sediment quality. The species composition and community 

structure of macroinvertebrates provide evidence of 

physical and chemical conditions present in a stream 

over timescales ranging from months to years 

(Cuffney and others, 1993). 

Intensive mining activity and highly mineralized 

rock formations have influenced the surface-water and 

streambed-sediment quality and aquatic biology in the 

upper reaches of the Uncompahgre River in western 

Colorado (fig. 1). Drainage from several abandoned 

mines and adits, combined with drainage from the
INTRODUCTION 3

NONMINING

SITES

MINING 

SITES

Uncompahgre

River

Sneffels

Canyon

Red Mountain

Imogene

Creek

Creek

Creek

Creek

8

7

6

5

4

Polk 

Creek

2

 Gulch French 1

 River

Colorado 3

EXPLANATION

Colorado River below Baker Gulch Basin

Polk Creek Basin

French Gulch Basin

Upper Uncompahgre River Basin

OURAY

Major mining site

Sampling sites

(number refers to table 1) 4

Town

RIDGWAY

PORTLAND

(BAKER)

(FARNCOMB)

(POLK)

Unconsolidated sediment deposits

Igneous and metamorphic deposits

Sediimentary deposits

Volcanic deposits

9 Nate Creek ditch

0

0

50

50

100 MILES

100 KILOMETERS

Figure 1. Location and basin surficial geology (King and Beikman, 1974a, b) of nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1995–98.
4 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Idarado and Camp Bird Mines and tailings in the Red 

Mountain and Canyon Creek watersheds (fig. 1), 

potentially contribute to the degradation of tributaries 

in the upper Uncompahgre River Basin (Moran and 

Wentz, 1974). The Uncompahgre River, which is a 

trout stream upstream from Red Mountain Creek, 

contains little or no aquatic life from the mouth of Red 

Mountain Creek to the mouth of Canyon Creek near 

Ouray and supports only a limited fishery for several 

miles downstream from that point (Rouse, 1970). 

The Upper Colorado River Basin (UCOL), 

which includes the Uncompahgre River, was selected 

for the NAWQA Program. A study was completed in 

the upper Uncompahgre River Basin in 1998 to better 

understand the relations of trace elements in water, 

streambed sediment, and aquatic life. The study area 

(fig. 1; table 1) is composed of five mining (miningaffected) sites in the upper Uncompahgre River Basin 

and three nonmining (minimally affected) sites in 

other drainage basins in the Upper Colorado River 

Basin. Water, streambed sediment, bryophyte (aquatic 

moss), benthic macroinvertebrate, and habitat data 

were collected at all sites during summer low-flow 

conditions. With the exception of streambed sediment, 

all sample media were collected in July and August 

1997 and 1998. Streambed-sediment samples were 

collected during low-flow conditions in September 

and October of 1995 and 1996. Although the 

streambed-sediment samples were not collected during 

the same years as the collection of data for water, 

bryophytes, macroinvertebrates, and habitat, these 

samples can still provide important information about 

the water-quality conditions at the sites because no 

known large-scale disturbances or mining activities 

occurred in the basin between sampling periods.

Purpose and Scope

The purposes of this report are to (1) compare 

trace-element concentrations in the water column, 

streambed sediment, and transplanted bryophytes in 

the study area, with emphasis on six selected trace 

elements (aluminum, arsenic, copper, iron, lead, and 

zinc); (2) estimate bioconcentration of the six selected 

trace elements by using transplanted bryophytes in the 

study area; (3) evaluate stream habitat conditions in 

the study area; (4) compare benthic macroinvertebrate 

community composition at nonmining and mining 

sites in the study area; and (5) report the relation 

between natural and human-related factors affecting 

the concentration of the six selected trace elements in 

water, streambed sediment, and transplanted bryophytes at nonmining and mining sites in the study area. 

Trace-element concentrations in water, streambed 

sediment, and transplanted bryophytes are presented; 

data describing the benthic macroinvertebrate community composition and qualitative stream habitat characteristics are given for five sites in the upper 

Uncompahgre River Basin and three sites in the Colorado River, French Gulch, and Polk Creek Basins in 

western Colorado during 1995–98.

Previous Work

Bioassessments have been used to monitor 

water and streambed-sediment quality for many years. 

In many cases, samples were collected to determine 

whether ecological integrity was present or to assess 

differences among mining-affected sites and nonaffected sites (Nelson and Campbell, 1995). An investigation of the effects of metal-mine drainage on 

surface-water quality in mining districts throughout 

Colorado was done by the USGS in cooperation with 

the Colorado Water Pollution Control Commission 

(Moran and Wentz, 1974). Moran and Wentz also 

studied the physical and chemical processes involved 

in metal-mine drainage and the effects on water and 

sediment quality and aquatic life. Moran and Wentz 

concluded that fish and macroinvertebrate populations 

had been virtually eliminated in Red Mountain Creek, 

and the decline in water quality of the upper 

Uncompahgre River was caused by metals, acid, and 

large amounts of iron hydroxide particles delivered to 

the Uncompahgre from Red Mountain and Canyon 

Creeks. Nelson and Campbell (1995) and Osmundson 

(1992) studied the effects of trace elements on aquatic 

life upstream and downstream from Ridgway Reservoir near Ridgway, Colo., and found the reservoir 

served as a sink for trace elements in the system.

Description of Study Area

The study area (fig. 1; table 1) is composed of 

five mining (mining-affected) sites in the upper 

Uncompahgre River Basin and three nonmining (minimally affected) sites in other drainage basins in the 

Upper Colorado River Basin. Mining sites were
INTRODUCTION

5

Table 1. Description of sampling sites in the Upper Colorado River Basin, Colorado, 1995–98 [ --, no data available; °F, degrees Fahrenheit]

Site 

number 

(fig. 1) Site name 

Site 

abbreviations 

Site 

identification 

 Site 

elevation 

 (feet)1

Site mean 

annual 

precipitation2

(inches per year)

Sit

an

temp

NONMINING SITES 

1 French Gulch above Farncomb Hill near Breckenridge, CO Farncomb 392838105572900 10,540 23.72 2 Polk Creek at Interstate Highway 70 near Vail, CO Polk 393527106143500 9,640 23.77 3 Colorado River below Baker Gulch near Granby, CO Baker 09010500 8,750 23.33 

MINING SITES 

4 Red Mountain Creek above Crystal Lake near Ironton, CO Red Mountain 375732107394000 9,610 -- 5 Canyon Creek below Squaw Gulch near Ouray, CO Canyon 380007107413600 8,514 -- 6 Uncompahgre River at Ouray, CO Ouray 380115107402001 7,707 26.94 7 Uncompahgre River above Cutler Creek near Ouray, CO Cutler 380448107420800 7,250 -- 8 Uncompahgre River near Ridgway, CO Ridgway 09146200 6,878 16.84 

Site 

abbreviations 

Stream 

order4

Predominant lithology 5 Predominant soil 

order6

Predominant vegetation 

type7

Predominant 

substrate8

Embedded

class9

NONMINING SITES

Farncomb 2 Sedimentary/igneous Alfisols Alpine-meadow-barren Cobble 5 Polk 3 Sedimentary/metamorphic Entisols Spruce-fir forest Cobble 4 Baker 3 Igneous metamorphic Alfisols Alpine-meadow-barren Cobble 4 

MINING SITES

Red Mountain 3 Igneous Inceptisols Alpine meadow-barren Cobble 4 Canyon 4 Igneous Alfisols Alpine meadow-barren Cobble 4 Ouray 5 Sedimentary/metamorphic Alfisols Spruce-fir forest Cobble 3 Cutler 5 Sedimentary Mollisols Spruce-fir forest Cobble 3 Ridgway 5 Sedimentary Entisols/Mollisols Pine-Douglas fir forest Cobble 3 

 1 Feet above sea level.  2 Site mean annual precipitation, for years 1995 to 1998, from the nearest climatic data-collection station according to Colorado Climate Center (2001) .  3 Site mean annual temperature, mean of monthly temperature data for years 1995 to 1998 from the nearest climatic data-collection station according to Colorado Climate Center (2001 4 Stream order determined according to Strahler (1952).

 5 Predominant lithology near the sampling site, modified from King and Beikman (1974a, b). 

 6 Predominant soil order near the sampling site, modified from Heil and others (1977).  7 Predominant vegetation type near the sampling site, modified from Kuchler (1964).  8 Predominant substrate sampled for benthic macroinvertebrates.  9 Rated on a scale from 1 (signifying over 75 percent of surface area of gravel, cobble, and boulder particles covered by fine sediment) to 5 (signifying less than 5 percent surface area o

 particles covered by fine sediment). 

 10 Rapid Bioassessment Protocols (modified) site habitat rating; see table 9 for more information.
6 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

selected on the upper Uncompahgre River to represent 

water-quality conditions affected by highly mineralized geology and mining land-use practices and were 

Red Mountain Creek above Crystal Lake near Ironton, 

Colo. (Red Mountain), Canyon Creek below Squaw 

Gulch near Ouray, Colo. (Canyon), Uncompahgre 

River at Ouray, Colo. (Ouray), Uncompahgre River 

above Cutler Creek near Ouray, Colo. (Cutler), and 

Uncompahgre River near Ridgway, Colo. (Ridgway). 

The nonmining sites were French Gulch above Farncomb Hill near Breckenridge, Colo. (Farncomb), Polk 

Creek at Interstate Highway 70 (I–70) near Vail, Colo. 

(Polk), and Colorado River below Baker Gulch near 

Granby, Colo. (Baker). Although some geographic and 

geological features differ among nonmining and 

mining sites (table 1), all sites are located in the 

Southern Rocky Mountain ecoregion (Omernik, 

1987). To minimize natural difference among site 

groups, the mean values of environmental variables of 

the three nonmining sites were used for statistical 

comparisons to mining sites.

The upper Uncompahgre River Basin in southwestern Colorado originates just west of the Continental Divide in the northern San Juan Mountains 

(southern part of basin) at an altitude of approximately 

12,200 feet above sea level and extends north and 

west approximately 20 miles to the town of Ridgway. 

The upper part of the river drains approximately 

150 square miles and travels through the towns of 

Ouray, Portland, and Ridgway (fig. 1, table 1). The 

mining sites are located in the northwestern part of the 

San Juan Mountains in the Red Mountain (southern 

part of basin in the Red Mountain Creek Basin), 

Mount Sneffels (western part of basin in the Sneffels 

Creek Basin), and Uncompahgre mining districts 

(central and northern parts of basin) of Ouray County 

in Colorado. The area is well known for historical 

metal-mining activities. Intensive mining activities 

began in the 1870's and continued to the mid-1980's; a 

few mines still operate. Early mine developments were 

concentrated in the Mount Sneffels district just west of 

Ouray where extensive amounts of copper, gold, lead, 

silver, and zinc were mined from vein deposits.

Geology

The general surficial geology of the 

Uncompahgre River study area consists of igneous and 

metamorphic bedrock of Precambrian age, sedimentary rocks of Paleozoic and Mesozoic age, volcanic 

deposits of Tertiary age, and unconsolidated sediment 

deposits of Quaternary age (fig. 1). The geology of the 

study area has undergone a series of five distinct 

episodes of deformation, some of which were accompanied by metamorphism, igneous activity, and mineralization (Westervelt and Sheriff, 1994).

The Precambrian bedrock includes diabase, 

granite dikes and sills, and exposed quartzite and slate. 

Limestones were deposited during the early Paleozoic, 

followed by thick beds of sandstone and shale, which 

were deposited through the late Mesozoic. Late 

Tertiary volcanism produced at least 15 variably 

mineralized calderas that compose the San Juan 

volcanic field. Mineralization occurred between 5 and 

15 million years ago following igneous activity associated with resurgent doming of the San Juan and 

Uncompahgre calderas and the formation of the 

Silverton caldera (Westervelt and Sheriff, 1994). 

These mineralized deposits compose most of the 

mined deposits in the study area.

General surficial geology of the Farncomb site 

(fig. 1) consists of sedimentary deposits (limestone, 

sandstone, and shale) of Cretaceous age and volcanic 

deposits of Cretaceous and Tertiary age. The surficial 

geology of the Polk site (fig. 1) includes igneous 

(granite) and metamorphic rocks (biotitic gneiss, 

migmatite, and schist) of Precambrian age, sedimentary deposits (conglomerate, limestone, sandstone, and 

shale) of Pennsylvanian age, and Quaternary landslide 

deposits, including locally derived talus and colluvium. The surficial geology of the Baker site (fig. 1) 

consists mainly of metamorphic rocks (gneiss, migmatite, and schist) of Precambrian age, but some sedimentary deposits (shale) of Cretaceous age and 

volcanic rocks (lava flows, breccias, and tuff) and 

glacial drift deposits of Tertiary and Quaternary age 

are present in the basin (King and Beikman, 1974a, b).

Climate

Rainfall and temperature in the study area 

(table 1) vary in relation to elevation. Average annual 

precipitation in the upper Uncompahgre River Basin 

ranges from less than 14 inches per year in the northernmost valleys to greater than 55 inches per year in 

the westernmost mountainous regions (D.W. Litke, 

U.S. Geological Survey, written commun., 1986). 

Approximately 30 to 40 percent of precipitation 

occurs as snowfall. Mean annual temperatures in 

Ouray generally range from 42 to 44 degrees Fahrenheit (Colorado Climate Center, 2001).
INTRODUCTION 7

The French Gulch area near Breckenridge 

receives about 19 to 30 inches of precipitation per 

year. Mean annual temperature for Dillon, north of 

Breckenridge, was 35.6 degrees Fahrenheit. The Polk 

Creek drainage basin near Vail normally receives 

about 19 to 30 inches of precipitation per year, and the 

mean annual temperature in the Vail area ranges from 

36 to 38 degrees Fahrenheit. Precipitation in the Baker 

Gulch area near Granby ranges from 20 to 26 inches 

per year, and mean annual temperatures range from 37 

to 39 degrees Fahrenheit (Colorado Climate Center, 

2001).

Land Use/Land Cover

Predominant land use/land cover (fig. 2) in the 

study area includes forest, rangeland, and tundra. 

Agriculture, which includes cropland, pasture, and 

confined animal feeding operations, is concentrated 

in the open valleys in the study area. Barren lands, 

urban development, and surface-water features constitute the smallest percentage of land use/land cover in 

all basins except at the Baker site where approximately 

17 percent of the basin includes other land-use types 

such as residential and recreational properties (Hitt, 

1995). 

Figure 2. Percentage of land use/land cover (Hitt, 1995) at nonmining and 

mining sites in the Upper Colorado River Basin, Colorado, 1995–98.

NONMINING SITES

Polk Baker

29.1%

70.4% 

0.5%

Farncomb

50%

43.5%

6.5%

67.5 %

14.6%

1.2%

16.7%

Rangeland and tundra 

Forest

Agriculture

Other

Uncompahgre Basin 

 

EXPLANATION

MINING SITES

45%

44%

7.5%

3.5%
8 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Acknowledgments

The authors would like to thank Boris C. 

Kondratieff, Colorado State University in Fort Collins, 

Colo., for identification and enumeration of macroinvertebrate samples; Timothy J. Canfield, U.S. Environmental Protection Agency at the Robert S. Kerr 

Environmental Research Center in Ada, Okla.; and 

Kenneth E. Kolm, Philippe Ross, and Ronald R.H. 

Cohen, Colorado School of Mines Environmental 

Science and Engineering Division in Golden, Colo., 

for their critical review of the design of the study. 

Norman E. Spahr and Robert W. Boulger, USGS, 

aided in data-collection efforts; Verlin C. Stephens, 

USGS, assisted with geographic information system 

support. Nancy E. Driver, USGS, provided project 

development and support. The authors thank Lawrence 

R. Deweese and Janet S. Heiny, USGS, for their critical review of the report. Appreciation is extended to 

Mary Kidd for editorial review, Alene J. Brogan for 

manuscript and layout, and John E. Evans for graphic 

design.

DATA COLLECTION AND ANALYSIS

Site Selection

The study area (fig. 1; table 1) is composed of 

five mining (mining-affected) sites in the upper 

Uncompahgre River Basin and three nonmining (minimally affected) sites in other drainage basins in the 

Upper Colorado River Basin. Mining sites were 

selected on the upper Uncompahgre River to represent 

water-quality conditions affected by highly mineralized geology and mining land-use practices. 

Nonmining sites were selected in other drainage 

basins due to a lack of nonmining sites in the 

Uncompahgre River Basin, and represent waterquality conditions considered to be minimally affected 

by mining activities. Although some geographic and 

geological features vary among nonmining and mining 

sites (table 1), all sites are located in the Southern 

Rocky Mountain ecoregion (Omernik, 1987). Omernik 

identified that ecoregions have similar patterns and 

composition of biotic and abiotic phenomena 

(geology, physiography, vegetation, climate, soils, 

land use, wildlife, and hydrology) that affect or reflect 

differences in ecosystem quality and integrity. 

Comparisons of chemical and biological conditions 

among nonmining and mining sites were used to determine potential effects of mining land use on the 

benthic macroinvertebrate communities at sites in the 

study area. To minimize natural difference among site 

groups, the mean values of environmental variables of 

the three nonmining sites were used for statistical 

comparisons to mining sites.

Sample Collection

Water-chemistry, streambed-sediment, transplanted bryophyte, and benthic macroinvertebrate 

samples were collected and stream habitat conditions 

were documented once at all sampling sites in the 

study area during low-flow conditions between 

October 1995 and July 1998. Water-chemistry, transplanted bryophyte, and benthic macroinvertebrate 

samples were collected and stream habitat was documented at all sampling sites in July 1997 except at the 

Polk and Baker sites, where samples and stream 

habitat information were collected in July 1998. 

Streambed sediments were collected at all sampling 

sites in October 1995 except at the Farncomb and 

Baker sites, where samples were collected in 

September 1996. Bryophytes (native aquatic moss that 

grows in southern Rocky Mountain streams) were 

transplanted at all sampling sites for 15 days during 

which water-column and benthic macroinvertebrate 

samples and physical water-quality data were 

collected. Stream habitat characteristics also were 

documented at each site. Although the streambedsediment samples were not collected during the same 

years as the collection of data for water, bryophytes, 

macroinvertebrates, and habitat, these samples can still 

provide important information about the water-quality 

conditions at the sites because no known large-scale 

disturbances or mining activities occurred in the basin 

between sampling periods. 

Water-column samples and physical waterquality data were collected according to USGS 

NAWQA protocols (Shelton, 1994). Physical waterquality data included alkalinity, dissolved oxygen, pH, 

specific conductance, and temperature. Streamflow 

(discharge) was measured using streamflow-gaging 

methods described by Rantz and others (1982) except 

at the Ridgway and Baker sites, where discharge was 

recorded from USGS streamflow-gaging stations. All 

water-column samples were analyzed at the USGS 
DATA COLLECTION AND ANALYSIS 9

National Water Quality Laboratory in Arvada, Colo., 

using methods described in Fishman and Friedman 

(1989). Water-column samples for trace elements 

included a less than 0.45-micrometer filtered 

(dissolved) sample and an unfiltered (total) sample in 

which subsequent analysis was performed. Results of 

water-chemistry analyses and physical water-quality 

data for all sampling sites are in Appendix D and in 

the USGS National Water Information System 

(NWIS).

Streambed sediments were collected from 

undisturbed, continuously wetted, depositional zones 

in the stream channel. Each depositional zone at a 

sampling site was subsampled at several locations, and 

the subsamples were composited (Shelton and Capel, 

1994). The samples were sieved in the field to less 

than 63 micrometers and submitted to the USGS 

Branch of Geochemistry Analytical Services Group 

Laboratory in Denver, Colo., and the USGS Research 

Laboratory in Atlanta, Ga., for analysis. Chemical 

preparation and analyses of the streambed-sediment 

samples followed a total digestion procedure 

(Horowitz and others, 1989). Streambed-sediment 

sample results for all sampling sites are in Appendix E 

and in the USGS National Water Information System 

(NWIS).

Samples of Hygrohypnum ochraceum, an 

aquatic bryophyte, were collected from Nate Creek 

ditch near Owl Creek Pass in Ouray County, Colo., 

during July 1997 and July 1998 to use as an indirect 

measure of bioconcentration of trace elements in 

biological communities at the sampling sites. Bryophytes were vigorously washed by hand, using tap 

water to remove sediment and attached macroinvertebrates. Deionized water was used as a final rinse. Tengram samples of spin-dried bryophytes were placed 

into 4-millimeter nylon mesh bags and transplanted at 

selected sites. Bags were attached to mason bricks 

using plastic O-rings and placed in the stream. To evaluate environmental variability, three bags per site were 

placed in riffle areas in the stream reach, including the 

Nate Creek ditch site, for a 15-day exposure period. 

According to Carter and Porter (1997), the maximum 

rate of uptake occurs during the first 10-day exposure 

for most trace elements, and significant differences in 

bryophyte trace-element concentrations can be found 

after as few as 10 days of exposure to ambient conditions. Bags were collected and bryophytes were 

removed and washed again, as described previously, 

and analyzed for trace elements (Nelson and Campbell, 1995; Nelson, 1996). Bryophyte samples were 

analyzed for trace elements discussed in this study 

using inductively coupled plasma-atomic absorption 

spectrophotometry for all elements except arsenic, 

which was analyzed using hydride generation-atomic 

absorption spectrophotometry at the Environmental 

Trace Substances Laboratory at the University of 

Missouri in Rolla, Mo. Results of analyses for transplanted bryophyte samples from all sampling sites are 

in Appendix F.

Benthic macroinvertebrate samples were 

collected from five representative areas of riffle habitat 

containing cobble substrates (richest-target habitat). 

Samples were collected using a slack sampler (kick 

net) with an area of 0.25 m2

. Five subsamples were 

collected and composited into one sample for each site 

for a total of 1.25 m2

. The samples were preserved 

with a 10-percent formalin solution. Macroinvertebrate samples were collected according to USGS 

NAWQA protocols (Cuffney and others, 1993) and 

were identified and enumerated at Colorado State 

University in Fort Collins. 

Benthic macroinvertebrate samples were rinsed 

of formaldehyde by using tap water and a sieve. Next, 

macroinvertebrates were picked or sorted from debris 

by using a binocular dissecting microscope at low 

power (about 10X) and placing the organism into 

labeled vials with 70- to 80-percent ethanol. Finally, 

organisms were identified to the lowest practical taxonomic level and counted (B.C. Kondratieff, Colorado 

State University, written commun., 1998). Density 

values were based on a 1-m2

 area and were obtained 

by dividing the number of organisms collected by the 

surface area of the sampler. Results of analyses for 

benthic macroinvertebrate samples from all sampling 

sites are in Appendix G.

A qualitative assessment of habitat conditions 

consisted of a field form characterizing instream 

habitat measures including substrate types, substrate 

embeddedness, channel alterations, bank stability, and 

riparian zone features. Each habitat variable was categorized, and a total score of the variables provided a 

qualitative assessment of each site. Habitat-assessment 

data were collected according to the U.S. Environmental Protection Agency’s Rapid Bioassessment 

Protocols (RBP) (Barbour and others, 1997).
10 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Data Analysis

Seventeen trace elements were analyzed in 

the water-column samples, 24 trace elements in 

streambed-sediment samples, and 19 trace elements in 

transplanted bryophytes. Many trace-element concentrations in the water column were near or less than the 

minimum reporting level or indicated little variation 

across the study area. Six trace elements—aluminum, 

arsenic, copper, iron, lead, and zinc—were selected for 

discussion in this study because they: (1) were 

frequently detected in most water, streambed sediment, and transplanted bryophyte samples; (2) showed 

some variability in concentrations; and (3) have 

aquatic-life standards or water-quality guidelines associated with them. Minimum reporting levels for watercolumn, streambed-sediment, and transplanted bryophyte samples are listed in Appendixes A, B, and C, 

respectively. Complete lists of all trace elements and 

their concentrations in the water column, streambed 

sediment, and transplanted bryophytes are in Appendixes D, E, and F, respectively.

Nonparametric statistical methods were used in 

the data analysis because original data cannot be 

formed to meet parametric statistical assumptions. 

Nonparametric methods do not depend on the distribution of the sampled population and are applicable to 

small sample sizes (fewer than 10). An alpha value of 

0.05 was used for the Mann-Whitney test to test for 

significant statistical differences between medians of 

two groups of data (nonmining and mining sites). 

Exact p-values less than or equal to 0.05 were used for 

the Spearman rank correlation to test significant statistical relations among trace-element concentrations in 

the different sampling media (water column, streambed sediment, and transplanted bryophytes); among 

trace-element concentrations and other water-quality 

parameters (pH, specific conductance, dissolved 

sulfate, suspended sediment, and dissolved organic 

carbon); and among trace-element concentrations and 

benthic macroinvertebrate metrics and indices.

A value of one-half of the method reporting 

level was substituted for concentrations in the water 

column that were less than the method reporting level 

(censored). The mean concentration of trace elements 

of the three bryophyte samples transplanted at each 

site was used for the analysis of the bryophyte data.

To compare water and streambed-sediment 

quality to the biological conditions at each site, a 

Water-Quality Score (WQS) was developed, based on 

information from this study, that includes five waterquality parameters that generally reflect trace-element 

chemistry in natural waters. The five WQS parameters, 

which were assumed to be independent of each other, 

were specific-conductance measurements and concentrations of suspended sediment, dissolved organic 

carbon, dissolved sulfate, and dissolved zinc in the 

water column. Each site was ranked in the same way 

with a score from one to eight that represented the 

quality of that constituent at that site relative to all the 

other sites. Except for dissolved organic carbon, all 

water-quality parameters were ranked high to low, 

corresponding to the lowest to highest concentrations 

of each of the five parameters at all sites. According to 

Rosenberg and Resh (1993), intermediate levels of 

organic enrichment may favor certain suspension- or 

deposit-feeding macroinvertebrate groups; therefore, 

dissolved organic carbon was ranked highest to lowest 

based on highest to lowest concentrations. Individual 

site WQS rankings for each of the five parameters 

were summed to arrive at a final WQS for a particular 

site. These scores represent the overall trace-element 

chemistry of the water and ultimately the effects on the 

macroinvertebrate community at these sites. The WQS 

was used to examine differences in water-quality 

conditions of nonmining and mining sites in the study 

area.

The Biological Condition Score (BCS) is a 

measure of the biological condition at a site, based on 

the benthic macroinvertebrate composition at that site, 

and was determined for all sites by using the U.S. 

Environmental Protection Agency Rapid Bioassessment Protocols III (benthic macroinvertebrates) 

(Plafkin and others, 1989). The BCS is an index that is 

determined by ranking eight biotic metrics that are 

commonly used in bioassessment studies. These 

metrics are taxa richness; the modified Hilsenhoff 

(1987) biotic index; the ratio of scraper to collectorfilterer abundances; the ratio of Ephemeroptera, 

Plecoptera, and Trichoptera (EPT) to chironomid 

abundances; the percentage contribution of one dominant taxon; the EPT index; the community loss index; 

and the ratio of shredders to total abundance of all 

macroinvertebrates at a site. Each metric then was 

assigned a score according to the percentage similarity 

(proportion of mining-site biotic metrics compared to 

nonmining-site biotic metrics) between the mining 

sites and the nonmining sites. To use the BCS effectively, the mean values of the three nonmining sites 

were used to develop the percentage similarity 
DATA COLLECTION AND ANALYSIS 11

between nonmining and mining sites. Scores of the 

eight metrics at each mining site were totaled and 

compared to a single total metric score for the 

nonmining sites. The percentage comparison between 

the total scores provides an overall evaluation of 

biological condition. 

According to Plafkin and others (1989), the 

percent comparisons to nonmining sites are used to 

obtain the biological condition category. The biological condition category represents the overall classification of each site based on the percentage 

comparisons of the BCS between nonmining and 

mining sites. Biological condition categories are 

nonimpaired (greater than 83 percent), slightly 

impaired (54 to 79 percent), moderately impaired (21 

to 50 percent), and severely impaired (less than 

17 percent). Plafkin and others (1989) suggested that 

assigning intermediate values (borderline values not 

directly assigned to one of the above category ranges) 

would require subjective judgment as to the correct 

placement of sites into biological condition categories 

and may need habitat and physiochemical data to aid 

in the decision process.

Quality-Assessment Procedures

Quality-assessment procedures were followed to 

ensure the consistency and accuracy of the data collection. Quality-control procedures for the water-chemistry samples included analysis of one split-replicate 

sample (12.5 percent of sample size) and one fieldblank sample (12.5 percent of sample size) collected at 

the same time as the environmental sample. A split 

replicate is a sample that is used to determine the variability associated with sample processing, handling, 

shipment, and analysis (Spahr and Boulger, 1997). A 

split-replicate sample was processed onsite by 

collecting twice the usual amount of water and splitting the water into two individual samples. Each 

sample was individually processed using the same 

techniques as described in Shelton (1994) and was 

submitted for laboratory analysis as one environmental 

sample and one split-replicate sample. Laboratory 

analyses for environmental and split-replicate samples 

are described in Fishman and Friedman (1989) and 

included analysis of major ions and trace elements. A 

field-blank sample was prepared using water that is 

free of the analytes of interest. The field-blank sample 

was passed through all field-cleaned sampling equipment and then processed as a normal water-quality 

sample. Laboratory analyses for field-blank samples 

are described in Fishman and Friedman (1989) and 

consisted of analysis of major ions and trace elements. 

The split-replicate results indicate that when 

concentrations were low (in the microgram per liter 

range), the differences between split-replicate concentrations were generally within 1 g/L of each other. 

When concentrations were high (100–1,000 g/L) the 

differences between split-replicate concentrations 

were generally within 2 percent of each other. The 

small differences in the split replicates indicate that 

sample processing and analysis did not introduce 

enough variation to affect interpretation of results. 

Field-blank results indicated that no detections were 

above the minimum reporting level; therefore, bias 

that could result from the contamination of environmental samples as a result of equipment cleaning, 

sample collection, processing, handling, shipping, and 

analysis (Spahr and Boulger, 1997) is minimal and did 

not introduce enough variation to affect interpretation 

of results.

Quality-control procedures for the collection of 

streambed sediments consisted of analysis of laboratory reference material (enriched soil) and one fieldreplicate sample (12.5 percent of sample size) 

collected at the same time as environmental samples. 

Field-replicate samples were collected to determine 

the variability in the sampling technique, in the laboratory analysis, and in the sampled depositional zones. 

Results of trace elements from the analysis of the laboratory reference material were within 3 standard 

deviations of the mean recovery of elements in the 

streambed-sediment reference material. The differences between environmental samples and fieldreplicate samples for aluminum, arsenic, copper, iron, 

lead, and zinc ranged from 0.10 to 19 percent and did 

not introduce enough variation to affect interpretation 

of results.

Quality-control procedures for the transplanted 

bryophytes consisted of using three replicate samples 

at each site to determine the variability of bioaccumulation processes in a single stream cross section. The 

coefficient of variation for bryophyte replicates ranged 

from 0.0 to 0.5 for the trace elements of interest, which 

may indicate variability in the cross section of the 

stream in which transplanted bryophytes were placed. 

For example, if transplanted bryophytes (bags) were 

placed in a section of the stream that had a decrease in 
12 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

flow, then these bags were possibly not exposed to 

trace elements in the water equal to a bag that was 

placed in a higher velocity zone. Because of this variation, the mean concentration of three replicate samples 

was used for the analyses of transplanted bryophyte 

data to represent an estimate of a cross-sectional 

sample. Laboratory quality-control procedures 

consisted of analysis of a matrix spike, standard reference material, replicate samples, and blank samples. 

The U.S. Fish and Wildlife Service’s Patuxent Analytical Control Facility quality-assurance program in 

Patuxent, Md., reviewed the results of the qualitycontrol samples. The accuracy was measured using 

spike recovery reference-material analysis. Blanksample analysis showed that trace-element concentrations in the blanks were less than minimum reporting 

levels for the analytes of interest and did not introduce 

enough variation to affect interpretation of results.

All sites were revisited and the habitat redocumented as a means of quality-control procedures for 

stream habitat assessment as described by the U.S. 

Environmental Protection Agency Rapid Bioassessment Protocols (Barbour and others, 1997). The redocumentation of habitat was conducted by the same 

investigator as the original habitat documentation and 

was used to determine the variability of the qualitative 

documentation procedures. Redocumented qualitative 

habitat data differed by less than 10 percent from the 

initial stream-habitat assessment and did not introduce 

enough variation to affect interpretation of results.

Quality-control procedures for benthic macroinvertebrate samples consisted of laboratory quality 

control and one field replicate (12.5 percent of sample 

size) to determine variability in a single stream reach. 

The relative percent difference (RPD) between replicate analyses was calculated using the formula:

Eighty percent of the biological metrics used in 

this report had RPD’s of less than 25 percent between 

environmental and field-replicate samples. Benthic 

macroinvertebrate sampling tends to be more variable 

than other forms of water-quality information, probably because of natural differences in the stream 

microhabitats and the collection of the sample in a 

stream reach. Changes in the microhabitat can cause 

certain types of macroinvertebrate groups to become 

more dominant than other macroinvertebrate groups. 

Laboratory quality control consisted of a second 

taxonomist identifying and enumerating taxa in one 

sample (12.5 percent of sample size) previously identified and enumerated. The variability in taxa identification and enumeration procedures consisted of less than 

a 10-percent difference for all samples except for a 

13-percent difference in total taxa for one sample and 

a 13-percent difference in total specimens for another 

sample. The results of laboratory and field-replicate 

quality-control measures indicate that benthic macroinvertebrate samples did not introduce enough variation to affect interpretation of results.

WATER-COLUMN SAMPLES AND 

PHYSICAL WATER-QUALITY 

PARAMETERS

Water-column samples were collected and physical water-quality parameters including discharge, 

alkalinity, dissolved oxygen, pH, specific conductance, and temperature were measured in the field at 

all sites during the biological sampling period. Alkalinity, pH, and specific conductance were analyzed 

using additional acid-preserved and chilled field 

samples obtained at the same time as field waterchemistry samples. Other water-quality parameters 

analyzed by the laboratory were dissolved solids, 

hardness, major ions and trace elements, suspendedsediment concentration, dissolved organic carbon, and 

suspended organic carbon. Water-column data 

collected for each site are listed in table 2 and 

Appendix D.

Specific conductance, dissolved sulfate, and 

concentrations of suspended sediment in the water 

column were generally higher at mining sites than at 

nonmining sites, whereas pH and dissolved organic 

carbon generally were lower at mining sites than at 

nonmining sites (fig. 3). Specific conductance, 

dissolved sulfate, and concentrations of suspended 

sediment and dissolved organic carbon were significantly different (p < 0.05) between nonmining and 

mining sites. Values for pH were not significantly 

different between nonmining and mining sites. 

RPD Sample1 – Sample2

Sample1 + Sample2

2 ---------------------------------------------------

= ---------------------------------------------------  100
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 13

CONCENTRATIONS AND DISTRIBUTION 

OF SELECTED TRACE ELEMENTS

Water Column

Water-column chemistry may provide information on the source and transport of trace elements in a 

stream system. The water-column chemistry is used to 

assess the physical (dissolved oxygen, pH, specific 

conductance, and temperature) and chemical (major 

ions and trace elements) characteristics of stream 

water (Shelton and Capel, 1994). Generally, water 

samples contain low concentrations of trace elements, 

whereas streambed-sediment samples commonly 

contain high concentrations.

Total concentrations of aluminum, copper, iron, 

lead, and zinc and most dissolved concentrations 

(except for lead and iron) in water-column samples 

were significantly different (p < 0.05) among 

nonmining and mining sites. Dissolved concentrations 

of aluminum, arsenic, copper, iron, lead, and zinc in 

the water column were generally higher at mining sites 

than at nonmining sites (fig. 4). A list of all trace 

elements for water-column samples for the study area 

is in Appendix D. Trace-element concentrations at 

nonmining sites were below minimum reporting levels 

for dissolved concentrations of arsenic, copper, and 

lead and for total concentrations of lead and zinc. One 

nonmining site had a detection of dissolved zinc and a 

detection of total copper, whereas most sampling sites 

had detections of dissolved and total aluminum and 

iron.

The State of Colorado aquatic-life standards are 

based on dissolved metal concentrations except for 

iron, which is based on the total-recoverable metal 

(Colorado Department of Public Health and Environment, 1999). Calculations of aquatic-life standards for 

copper, lead, and zinc were based on the hardness of 

the water during the sampling period. Sample concentrations of trace elements in the water column were 

compared to the acute and chronic concentrations for 

aquatic life (Colorado Department of Public Health 

and Environment, 1999) (table 3).

Dissolved aluminum concentrations ranged 

from 3.8 g/L at the Farncomb site to 9,174 g/L at the 

Red Mountain site. The Red Mountain site is the only 

site with concentrations that exceeded the Colorado 

aquatic-life standards for acute and chronic concentrations of aluminum. Dissolved arsenic concentrations 

were not detected except at the Ridgway site, where 

the arsenic concentration was at the minimum 

reporting level of 1 g/L. Concentrations of dissolved 

copper ranged from less than 1 g/L at all nonmining 

sites to 338 g/L at the Red Mountain site. Samples

Table 2. Selected water-column data for samples from nonmining and mining sites in the Upper Colorado 

River Basin, Colorado, 1997–98 

[ft3/s, cubic feet per second; °C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees 

Celsius; CaCO3, calcium carbonate] 

Site 

abbreviation 

(see table 1 

for full site 

names) 

Discharge 

(ft3

/s) 

Temperature 

(°C) 

 pH, 

field 

Alkalinity, 

field 

(mg/L as 

CaCO3) 

Dissolved 

oxygen 

(mg/L) 

Specific 

conductance, 

field 

(μS/cm) 

Dissolved 

solids 

(mg/L) 

Hardness, 

total 

(mg/L as 

CaCO3) 

Suspended 

sediment 

(mg/L) 

Dissolved 

organic 

carbon 

(mg/L) 

NONMINING SITES 

Farncomb 13.4 4.9 7.7 24 8.7 72 44 34 0.9 2.6 

Polk 6.6 6.8 8.1 47 8.8 94 53 45 2.4 1.4 

Baker 43.0 14 7.8 25 8.0 62 39 27 2.0 1.9 

MINING SITES 

Red Mountain 52.4 6.4 3.8 0 8.3 415 264 120 16 0.3 

Canyon 170 9.9 7.5 27 8.2 161 89 70 3.4 0.3 

Ouray 260 8.5 6.9 11 8.7 194 111 80 18 0.2 

Cutler 294 10 7.6 18 8.5 222 129 93 14 0.3 

Ridgway 379 15 8.1 69 7.5 400 242 170 45 0.8 
14 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

2

4

6

8

10

0

25

50

75

100

125

150

175

200

0

50

100

150

200

250

300

350

400

450

500

0

5

10

15

20

25

30

35

40

45

50

0

0.5

1.0

1.5

2.0

2.5

3.0

PH, IN STANDARD UNITS

 SPECFIC CONDUCTANCE, INMICROSIEMENS PER CENTIMETER

 DISSOLVED SULFATE,IN

 MILLIGRAMS PER LITER DISSOLVED ORGANIC CARBON,

 IN MILLIGRAMS PER LITER

SUSPENDED SEDIMENT, IN

 MILLIGRAMS PER LITER

EXPLANATION

Ouray

Number of samples (n)

(n = 5)

(n = 3)

NONMINING MINING

NONMINING MINING

NONMINING MINING

NONMINING MINING

NONMINING MINING

Nonmining sites

Mining sites

Red Mountain

Canyon

Baker

Polk

Farncomb

Cutler

Ridgway

Site group median concentration

Figure 3. Selected physical and chemical water-column data for samples from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1997–98. Data given in Appendix D.
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 15

 Minimum reporting level (MRL)

EXPLANATION

Ouray

Number of samples (n)

Nonmining sites (n = 3) Mining sites (n = 5)

Red Mountain

Canyon

Baker

Polk

Farncomb

Cutler

Ridgway Site group median concentrationARSENIC, IN MICROGRAMS PER LITER

LEAD, IN MICROGRAMS 

 PER LITER

COPPER, IN MICROGRAMS PER LITER

IRON, IN MICROGRAMS PER LITER ZINC, IN MICROGRAMS 

 PER LITER

ALUMINUM, IN MICROGRAMS  PER LITER

0

0.5

1.0

1.5

0.1

1

10

100

1,000

0.1

1

10

100

0.1

1

10

100

1,000

0.1

1

10

100

1,000

10,000

0.1

1

10

100

1,000

10,000

100,000

NONMINING MINING

NONMINING MINING

NONMINING MINING MINING NONMINING

NONMINING MINING

NONMINING MINING

MRL =1

MRL =1

MRL =1

MRL =1

MRL =1

MRL =3

Figure 4. Concentrations of dissolved aluminum, arsenic, copper, iron, lead, and zinc in water-column 

samples from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98.

Data given in Appendix D.
16 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Table 3. Comparison of acute and chronic aquatic-life standards established by the Colorado Department of PubEnvironment (1999) and selected trace-element dissolved and total concentrations in water-column samples from sites in the Upper Colorado River Basin, Colorado, 1997

–98 

[All values in micrograms per liter; shaded values exceed one or more Colorado aquatic-life standards, --, no data available; <, less than] 

Site abbreviation (see table 1 for full site names)

Aluminum, 

acute 

standard 

(dissolved) 

Aluminum,

chronic 

standard 

(dissolved) 

Aluminum 

from this 

study 

(dissolved) 

Arsenic, 

acute 

standard1

(dissolved) 

Arsenic, 

chronic 

standard1

(dissolved) 

Arsenic 

from this 

study 

(dissolved) 

Copper, 

acute 

standard1

(dissolved) 

Co

ch

sta

(diss

NONMINING SITES 

Farncomb 750 87 3.8 360 150 <1 6.42 Polk 750 87 5.6 360 150 <1 8.36 Baker 750 87 9.6 360 150 <1 5.17 

MINING SITES

Red Mountain 750 87 2,39,174 360 150 <1 21.1 1Canyon 750 87 10.9 360 150 <1 12.7 Ouray 750 87 17.0 360 150 <1 14.4 Cutler 750 87 35.5 360 150 <1 16.6 1Ridgway 750 87 63.9 360 150 1 29.2 1Site abbreviation (see table 1 for full site names)

Iron, 

acute 

standard 

(total) 

Iron, 

chronic 

standard 

(total) 

Iron 

from this 

study 

(total) 

Lead, 

acute 

standard1

(dissolved)

Lead, 

chronic 

standard1

(dissolved)

Lead from 

this study 

(dissolved)

Zinc, acute 

standard1 

(dissolved) 

Z

ch

sta

(dis

NONMINING SITES 

Farncomb -- 1,000 42 16.8 0.84 <1 46.9 Polk -- 1,000 54 26.3 1.26 <1 59.5 Baker -- 1,000 404 11.6 0.61 <1 38.6 

MINING SITES

Red Mountain -- 1,000 39,990 129 5.04 320 137 1Canyon -- 1,000 123 53.9 2.35 <1 86.5 Ouray -- 1,000 32,150 66.9 2.84 <1 96.9 Cutler -- 1,000 31,795 85.3 3.51 <1 110 1Ridgway -- 1,000 31,435 226 8.25 <1 183 1

 1Colorado acute and chronic aquatic-life standards calculated from equations based on the dissolved metal concentrations and the hardness of the water at the time of sampling 

 Health and Environment, 1999).

 2 Sites from this study that exceeded the Colorado acute aquatic-life standards. 

 3Sites from this study that exceeded the Colorado chronic aquatic-life standards.
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 17

from the Red Mountain site and the Ouray site had 

concentrations of copper that exceeded the Colorado 

aquatic-life standard for acute and chronic concentrations. Dissolved iron concentrations ranged from less 

than 3 g/L at the Ridgway site to 5,145 g/L at the 

Red Mountain site (Appendix D), and total iron 

concentrations ranged from 42 g/L at the Farncomb 

site to 9,990 g/L at the Red Mountain site. Iron 

concentrations exceeded the Colorado aquatic-life 

standards for chronic concentrations at all mining sites 

except the Canyon site. Dissolved lead concentrations 

were detected only at the Red Mountain site at 

20 g/L, which exceeded the Colorado aquatic-life 

standard for chronic concentrations. Concentrations of 

dissolved zinc at nonmining sites ranged from less 

than 1 g/L at the Polk and the Baker sites to 1.4 g/L 

at the Farncomb site, which was just above the 

minimum reporting level (1 g/L). Concentrations of 

dissolved zinc at mining sites ranged from 18 g/L at 

the Ridgway site to 559 g/L at the Red Mountain site. 

All of the mining sites except the Ridgway site had 

zinc concentrations exceeding Colorado aquatic-life 

standards for acute or chronic concentrations.

Streambed Sediment

Trace elements commonly are a natural component of streambed sediment. Concentrations of trace 

elements in streambed sediment are strongly affected 

by the particle-size distribution of the sample and tend 

to be associated with fine-grained sediments (Brook 

and Moore, 1988). To determine if concentrations of 

trace elements in streambed sediments are elevated, 

concentrations were compared to mean natural background concentrations for soils in the Western United 

States (Jenkins, 1981; Salomons and Förstner, 1984; 

Shacklette and Boerngen, 1984). Concentrations of 

trace elements both at nonmining and mining sites 

were higher than suggested mean background concentrations for soils in the Western United States except 

for some concentrations of arsenic, copper, and lead at 

nonmining sites (table 4). The Farncomb nonmining 

site is heavily mineralized (Apodaca and others, 1995) 

and therefore had high naturally occurring concentrations of some trace elements. Arsenic, copper, lead, 

and zinc concentrations were from about two to eight 

times higher at the Farncomb site than at the other two 

nonmining sites.

Trace-element concentrations in streambed sediments at mining sites generally were higher than the 

ranges of concentrations at nonmining sites (fig. 5). 

Concentrations of copper, lead, and zinc in streambed 

sediment were significantly different (p < 0.05) at 

nonmining sites compared to concentrations at mining 

sites. A list of all trace elements for streambedsediment samples for the study area is in Appendix E.

Currently (1999), no State or Federal guidelines 

exist in the United States for trace elements in streambed sediment; however, the Canadian Council of 

Ministers of the Environment has developed interim 

freshwater sediment-quality guidelines for those trace 

elements that are considered most toxic to aquatic life 

(Canadian Council of Ministers of the Environment, 

1999). Two guideline values have been developed: a 

lower value, referred to as the “interim sedimentquality guideline” (ISQG), and an upper value, 

referred to as the “probable effect level” (PEL). The 

Canadian ISQG represents the concentration below 

which there is little probability of adverse effects to 

aquatic biota. The PEL defines the concentration 

above which adverse effects to aquatic biota are 

expected to occur frequently. Both guideline values are 

based on the total concentration of a chemical in bulk 

sediment and correspond with respective responses of 

benthic macroinvertebrates in freshwater lake environments (Canadian Council of Ministers of the Environment, 1995). Therefore, comparison of the sediment 

concentrations for the less than 63-micrometer-diameter fraction analyzed in this study (table 5) may overestimate the concentrations in bulk sediment, therefore 

may overestimate the potential adverse affects on 

aquatic life (Deacon and Stephens, 1998). 

Concentrations of some trace elements in 

streambed sediments were possibly elevated enough to 

adversely affect the biota at some sites (table 5). 

Trace-element concentrations at nonmining sites were 

above the ISQG for arsenic, copper, lead, and zinc at 

the Farncomb site, lead and zinc at the Polk site, and 

arsenic and zinc at the Baker site. With the exception 

of arsenic, lead, and zinc at the Farncomb site, 

nonmining-site trace-element concentrations did not 

exceed the Canadian Sediment Quality Guidelines 

PEL. Generally, all trace-element concentrations in 

streambed sediments at mining sites exceeded the 

ISQG and PEL except at the Red Mountain site, where 

concentrations of copper and zinc were below the 

PEL, and the Canyon site, where concentrations of 

copper were below the PEL.
18 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Table 4. Mean concentrations and ranges of concentrations for selected trace elements in soils in the Western United Stasediment samples from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1995

–96 

[All values are in micrograms per gram, dry weight, unless noted as percent (%); <, less than; μm, micrometer; --, no data available] 

 Western United States soils 

Upper Colorado River Basin s

Trace 

element 

Mean 

concentrations 

from 

Salomons and 

Förstner 

(1984)1

Mean 

concentrations 

from 

Shacklette and 

Boerngen 

(1984)1

Range of 

concentrations 

from 

Jenkins 

(1981)1

Mean of 

concentrations for 

nonmining sites 

from this study 

(<63-μm fraction)

Range of 

concentrations for 

nonmining sites 

from this study 

(<63-μm fraction) 

conc

min

(<63-

MINING SITES 

Aluminum (%) -- 5.8 -- 7.8 7.5

–8.3 

Arsenic -- 5.5 1.8

–6.6 23.6 4.8

–59 

Copper 25.8 21 20 30.7 21

–46 

Iron (%) 3.2 2.1 -- 4.0 3.6

–4.6 

Lead 29.2 17 10

–40 72 23

–150 

Zinc 59.8 55 -- 303 130

–630 

 1 Background concentrations established for Western United States soils. 
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 19

EXPLANATION

Ouray

Number of samples (n)

Nonmining sites (n = 3) Mining sites (n = 5)

Red Mountain

Canyon

Baker

Polk

Farncomb

Cutler

Ridgway Site group median concentration

CCME PEL sediment- quality guideline ARSENIC, IN MICROGRAMS PER GRAM

LEAD, IN MICROGRAMS  PER GRAM

COPPER, IN MICROGRAMS  PER GRAM

 IRON, IN PERCENT

ZINC, IN MICROGRAMS  PER GRAM

 ALUMINUM, IN PERCENT

0

25

50

75

100

125

150

175

200

0

100

200

300

400

500

600

700

800

0

100

200

300

400

500

600

700

800

900

0

200

400

600

800

1,000

1,200

0

5

10

15

20

5

6

7

8

9

10

NONMINING MINING

NONMINING MINING

NONMINING MINING NONMINING MINING

NONMINING MINING

NONMINING MINING

PEL = 91.3

PEL = 315

PEL = 197

PEL = 17

No PEL 

No PEL 

Figure 5. Concentrations of aluminum, arsenic, copper, iron, lead, and zinc in the less than 

63-micrometer fraction of streambed-sediment samples from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1995–96, with comparison to Canadian Council of Ministers 

of the Environment (CCME) probable effect level (PEL) sediment-quality guidelines. Data given in 

Appendix E.
20 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Transplanted Bryophytes

Transplanted aquatic bryophytes may provide 

information about the concentration and bioavailability of trace elements (Nelson and Campbell, 1995; 

Carter and Porter, 1997). When combined with other 

chemical and biological data, concentrations of trace 

elements in transplanted bryophytes may provide a 

useful measure of bioconcentration of trace elements. 

Other studies have indicated that results of bryophyte 

tissue analyses correspond to water-chemistry conditions (Wehr and Whitton, 1983; Jones, 1985; Jones 

and others, 1985; Mersch and Johansson, 1993). 

Studies by Carter and Porter (1997) indicated that 

bryophytes (H. ochraceum) are efficient at identifying 

sites contaminated by arsenic, cadmium, copper, lead, 

manganese, molybdenum, and zinc. Transplanted 

bryophytes can be used to compare the total concentration of metals in bryophyte samples to concentrations 

in the corresponding water column and streambed 

sediment (Carter and Porter, 1997).

Concentrations of trace elements in samples of 

transplanted bryophytes from all sites in the study area 

are a function of adsorption and absorption processes. 

A variable percentage of total metal attributed to a 

given bryophyte sample is attached to the external 

surface of the plant, and the remainder is bound in the 

plant cells; the proportions can vary with each metal 

(S.D. Porter, U.S. Geological Survey, oral commun., 

2000). In this study, the concentration of trace 

elements in the bryophyte tissue was not differentiated 

between adsorption and absorption processes; therefore, reported concentrations are total concentrations 

of trace element on the external surface as well as 

within the bryophyte tissue. 

Trace elements occur naturally in stream 

systems and may be readily bioavailable for plant 

uptake. To determine if concentrations of trace 

elements in transplanted bryophytes were elevated, 

concentrations were compared to initial concentrations 

of the source bryophyte material from the Nate Creek 

ditch site (table 6). Generally, concentrations of trace 

elements at nonmining sites were about the same or 

slightly higher than the initial concentrations in the 

transplanted bryophytes. Slightly increased traceelement concentrations in the transplanted bryophytes 

at the nonmining sites may be due to naturally mineralized geologic conditions upstream from these sites. 

Bryophyte trace-element concentrations at the 

Farncomb site were the highest among nonmining 

sites for concentrations of aluminum, arsenic, iron, 

lead, and zinc. Concentrations of aluminum, arsenic, 

copper, iron, lead, and zinc in transplanted bryophytes 

at mining sites were higher than source bryophyte 

material (table 6) concentrations except at the Red 

Mountain site, where zinc concentrations were lower 

than the initial concentrations. Two possible factors 

could account for the lower zinc concentrations in the 

transplanted bryophytes at the Red Mountain site: 

(1) the low pH at this site may have stressed the bryophytes enough that the uptake process was disrupted, 

and zinc uptake did not readily occur; and (2) the high 

concentrations of iron hydroxide precipitate present at 

this site may have physically blanketed the bryophyte

Table 5. Comparison of sediment-quality guidelines from Canadian Council of Ministers of the 

Environment (1999) and selected trace-element concentrations in streambed-sediment samples from 

nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1995–96

[All values are in micrograms per gram, dry weight] 

Trace 

element 

Interim sediment-quality 

guideline (ISQG)1

Probable effect level 

(PEL)2

Sites with concentrations above PEL3

NONMINING SITES MINING SITES 

Arsenic 5.9 17 1 4, 5, 6, 7, 8 

Copper 35.7 197 none 6, 7, 8 

Lead 35 91.3 1 4, 5, 6, 7, 8 

Zinc 123 315 1 5, 6, 7, 8 

 1 The ISQG represents the concentration in bulk sediment below which there is little probability of adverse effects to aquatic biota (Canadian 

Council of Ministers of the Environment, 1995).

 2 The PEL defines the concentration in bulk sediment above which adverse effects to aquatic biota are predicted to occur frequently (Canadian 

Council of Ministers of the Environment, 1995).

 3 Sites from this study analysis of the less than 63-micrometer fraction. Site numbers correspond to figure 1 and table 1.
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 21

tissue and altered the uptake processes that occurred 

on the bryophyte surfaces. Transplanted bryophytes 

collected at this site were heavily stained with iron 

hydroxides even after a thorough cleaning procedure 

to prepare bryophytes for analysis.

Trace-element concentrations in transplanted 

bryophytes at mining sites were generally higher than 

the ranges of concentrations at nonmining sites 

(fig. 6). Concentrations of arsenic, copper, iron, and 

lead in transplanted bryophytes were significantly 

different (p < 0.05) among nonmining and mining 

sites. A list of all trace elements for transplanted bryophyte samples for the study area are listed in 

Appendix F.

The relative rank (maximum trace-element 

concentration from all sites divided by the bryophyte 

source material trace-element concentration) of traceelement bioconcentration by bryophytes was determined for aluminum, arsenic, copper, iron, lead, and 

zinc. The relative ranking of trace-element bioconcentration by transplanted bryophytes was lead > copper > 

zinc > arsenic > iron > aluminum, which indicated that 

the transplanted bryophytes tended to favor the accumulation of lead, copper, and zinc more than arsenic, 

iron, and aluminum.

Bioconcentration factors (BCF’s are computed 

as the concentration of trace element in bryophyte 

tissue divided by dissolved trace-element concentration in the water column) for 15-day exposure period 

(BCF15) were calculated using the concentrations of 

aluminum, arsenic, copper, iron, lead, and zinc in 

transplanted bryophytes and instantaneous dissolved 

water-column concentrations (table 7). When concentrations of trace elements in the water were lower than 

the reporting level, BCF15’s were calculated using 

one-half of the method reporting level. BCF15’s were 

significantly different (p < 0.05) for arsenic, lead, and 

zinc at nonmining sites compared to mining sites. 

Differences in BCF15 between nonmining and mining 

sites are probably related to differences in geochemical sources of those constituents and resulting 

concentrations in the water-column samples (Carter 

and Porter, 1997).

Relation among Selected Trace-Element 

Concentrations in the Water Column, 

Streambed Sediment, and Transplanted 

Bryophytes

The relation among concentrations of trace 

elements in different sampling media (water column, 

streambed sediment, and transplanted bryophytes) at 

all sampling sites was examined using the Spearman 

rank correlation (table 8). Generally, as concentrations 

of aluminum, copper, iron, lead, and zinc increased in 

streambed sediments, these elements also increased in 

transplanted bryophytes. In most cases, concentrations 

of copper were lower in streambed sediment than in 

transplanted bryophytes, whereas concentrations of 

lead were higher in streambed sediment than in transplanted bryophytes for all sites. In general, concentraTable 6. Comparison of selected trace-element concentrations in bryophyte (Hygrohypnum ochraceum) 

source material to trace-element concentrations in transplanted bryophytes from nonmining and mining 

sites in the Upper Colorado River Basin, Colorado, 1997–98 

[All concentrations are in micrograms per gram, dry weight] 

Trace element 

Initial concentrations of 

bryophyte source material1

Range of concentrations for sites from this study2

 NONMINING SITES MINING SITES 

Aluminum 3,702 2,645–6,690 3,960–9,390 

Arsenic 1.08 1.0–4.0 6.1–15 

Copper 41.8 34.3–36.4 286–1,970 

Iron 8,594 6,395–14,533 14,200–99,150 

Lead 3.4 2.5–14.7 34.2–299 

Zinc 67.2 82.5–137 45.3–2,010 

 1 Represents the mean trace-element concentrations in bryophyte source material for samples from the Nate Creek ditch site, 1997 and 1998. 2 Represents the trace-element concentrations in transplanted bryophytes for samples from nonmining and mining sites, 1997 and 1998.
22 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

EXPLANATION

Ouray

Number of samples (n)

Nonmining sites (n = 3) Mining sites (n = 5)

Red Mountain

Canyon

Baker

Polk

Farncomb

Cutler

Ridgway

Site group median concentration

Bryophyte source material 

concentration (BSMC)

ARSENIC, IN MICROGRAMS  PER GRAM

LEAD, IN MICROGRAMS  PER GRAM COPPER, IN MICROGRAMS PER GRAM

IRON, IN MICROGRAMS  PER GRAM ZINC, IN MICROGRAMS 

 PER GRAM

ALUMINUM, IN MICROGRAMS PER GRAM

0

2

4

6

8

10

12

14

16

18

20

0

500

1,000

1,500

2,000

2,500

0

50

100

150

200

250

300

350

400

0

500

1,000

1,500

2,000

2,500

1,000

10,000

100,000

1,000,000

1,000

10,000

100,000

NONMINING MINING

NONMINING MINING

NONMINING MINING NONMINING MINING

NONMINING MINING

NONMINING MINING

BSMC= 3,702

BSMC= 1.05

BSMC= 41.8

BSMC= 8,594

BSMC= 3.4 BSMC= 67.2

Figure 6. Concentrations of aluminum, arsenic, copper, iron, lead, and zinc in transplanted bryophyte 

samples from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98, with 

comparison to initial concentrations of bryophyte source material from Nate Creek ditch, Colorado 1997–98.

Data given in Appendix F.
CONCENTRATIONS AND DISTRIBUTION OF SELECTED TRACE ELEMENTS 23

Table 7. Bioconcentration factors (BCF15) for transplanted bryophytes (Hygrohypnum ochraceum) 

after 15-day exposure period to ambient conditions at nonmining and mining sites in the Upper 

Colorado River Basin, Colorado, 1997–98 

[Concentrations are mean values of three bryophyte replicate samples; --, unable to determine because concentrations 

of trace elements in the water were below reporting level] 

Trace element (BCF15)

1

Site 

abbreviations Aluminum Arsenic Copper Iron Lead Zinc 

NONMINING SITES 

Farncomb 1,760 -- -- 1,710 -- 97.9 

Polk 804 -- -- 512 -- -- 

Baker 276 -- -- 59.2 -- -- 

MINING SITES

Red Mountain 0.43 -- 0.95 19.3 14.9 0.08 

Canyon 620 -- 168 3,740 -- 16.3 

Ouray 552 -- 123 79.9 -- 4.15 

Cutler 247 -- 611 708 -- 19.7 

Ridgway 103 6.1 144 -- -- 49.3 

 1 BCF15 = concentration of trace element in bryophyte tissue for 15-day exposure period divided by dissolved concentration of trace 

element in the water column.

Table 8. Spearman rank correlations of selected trace-element concentrations in the 

water-column, streambed-sediment, and transplanted bryophyte samples at nonmining 

and mining sites in the Upper Colorado River Basin, Colorado, 1995–98 

[All values represent rho values corrected for ties from Spearman rank correlation statistical test, p-value 

less than or equal to 0.05] 

Trace 

elements Aluminum Arsenic Copper Iron Lead Zinc 

Aluminum 0.75b+c 0.85a 

Arsenic 0.81c 

Copper 0.90b+c 0.78b

 

Iron 0.85b+c 

Lead 0.76b

 0.81b, 0.88c 0.97b+c 

Zinc 0.90a

 0.89b+c

 a Concentration positively correlated in water-column samples. b Concentration positively correlated in streambed-sediment samples. c Concentration positively correlated in transplanted bryophyte samples. b+c Concentrations positively correlated between streambed-sediment and transplanted bryophyte samples.
24 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

tions of aluminum and iron in streambed sediment and 

transplanted bryophytes decreased in a downstream 

direction in the upper Uncompahgre River (between 

the Ouray and the Ridgway sites). Samples from the 

Red Mountain site had (1) the highest concentrations 

of dissolved aluminum, copper, iron, lead, and zinc in 

the water column, (2) the highest concentrations of 

arsenic, iron, and lead in streambed-sediment samples, 

and (3) the highest concentrations of iron and lead in 

transplanted bryophyte samples than any other site. In 

general, concentrations of trace elements in streambed 

sediment and transplanted bryophytes tended to be 

more closely correlated with each other than either of 

them were with concentrations in the water column. 

Also, concentrations of aluminum, copper, iron, lead, 

and zinc in bryophytes may be useful for the estimation of concentrations of these constituents in streambed sediment.

Distributions of zinc concentrations in the water 

column, streambed sediment, and transplanted bryophytes were generally representative of the variations 

of other trace-element concentrations among the 

different sampling media (fig. 7). Although concentrations of dissolved zinc in the water column were below 

the reporting level at nonmining sites, zinc was present 

in the streambed sediment and the transplanted bryophytes. Zinc probably occurs in streambed sediment at 

the Farncomb site because highly mineralized geology 

provides a source of trace elements at that site. At the 

mining sites, zinc was present in the water column as 

well as in streambed sediment and transplanted bryophytes. The Red Mountain site had the highest concentrations of zinc in the water column, probably due to 

the low pH (3.5) of the water. Zinc and other trace 

elements tend to occur in the dissolved phase when the 

stream pH is low, as seen at the Red Mountain site. 

Generally, in this study, concentrations of zinc and 

other trace elements were higher in the streambed 

sediment and transplanted bryophytes than in the 

water column. Typically, as concentrations of zinc 

increased in the streambed sediment, they also 

increased in the transplanted bryophytes.

Figure 7. Distributions of zinc concentrations in water-column, streambed-sediment, and 

transplanted bryophyte samples from nonmining and mining sites in the Upper Colorado 

River Basin, Colorado, 1995–98.

0

500

1,000

1,500

2,000

2,500

0

100

200

300

400

500

600

Transplanted bryophytes

 ,

Water Streambed sediment

Zinc Concentrations

EXPLANATION

NONMINING MINING

 SEDIMENT AND BRYOPHYTES,

IN MICROGRAMS PER GRAM

 DISSOLVED ZINC CONCENTRATIONS IN WATER, IN MICROGRAMS PER LITER

RED

MOUNTAIN

CANYON

OURAY

CUTLER

RIDGWAY

FARNCOMB

POLK

BAKER
STREAM HABITAT CHARACTERISTICS 25

STREAM HABITAT CHARACTERISTICS

Biological communities may be affected by 

habitat quality as well as by water and streambedsediment quality. Stream habitat assessment is an 

important means of determining physical factors 

affecting biological communities. Stream habitat was 

considered on two major scales: the small-scale reachlevel habitat and the large-scale basin-level habitat. 

Reach-level habitat includes physical features of the 

stream and the surrounding riparian zone such as 

channel substrate, vegetation, and stream geomorphology along about a 492-foot reach of stream. 

Basin-level habitat or environmental setting (climate, 

elevation, and gradient) describes general physical 

features of the entire basin.

The U.S. Environmental Protection Agency 

Rapid Bioassessment Protocols (RBP) (Barbour and 

others, 1997) were used to separate water-quality 

effects from habitat effects on biological communities. 

RBP’s include a descriptive, visual-based habitat 

assessment for riffle/run-dominated streams. Habitat 

conditions were determined using RBP’s that were 

modified for use in this study and include the evaluation of instream habitat, channel morphology, and 

riparian and bank structure at a site (table 9). Habitat 

characterization for each of the eight sites was documented at the time of benthic macroinvertebrate 

sampling at the sites.

Stream habitat was rated as optimal to suboptimal using the RBP habitat characterization for all 

sites in the study area (table 10). All study sites except 

the Ouray and Cutler sites were rated as having 

optimal habitat for biological communities. The Ouray 

and Cutler sites were rated as suboptimal because of 

disturbances in the stream habitat. At the Ouray site, 

the river has been artificially channelized with riprap 

and cement, and large amounts of water are forced to 

move through small urban drainage-control structures. 

A series of diversions, bridges, and construction in the 

riparian zone of the Cutler site has contributed to 

increased erosion and riparian vegetation loss at this 

site. Increased sediment deposition and the resulting 

highly embedded substrate may affect the availability 

of macroinverebrate habitat at the Ridgway site. 

Generally, stream habitat conditions were similar 

between nonmining and mining sites and were suitable 

for macroinvertebrate communities.

BENTHIC MACROINVERTEBRATE 

COMMUNITY STRUCTURE

The composition of benthic macroinvertebrate 

communities has been used to monitor effects of trace 

elements on streams since the early 1900’s (Carpenter, 

1924). Because macroinvertebrates are continuously 

exposed to water and sediment in streams, these organisms integrate contaminants over time and provide a 

measure of water and sediment quality. Typical indicators of metal-polluted streams include decreased 

macroinvertebrate abundance, decreased species richness, and a shift in community composition from 

sensitive taxa, such as some species of Ephemeroptera 

(mayflies), Plecoptera (stoneflies), and Trichoptera 

(caddisflies) (EPT), to tolerant taxa, such as some 

species of Chironomidae (midges) (Clements, 1995).

Generally, the composition of the benthic 

macroinvertebrate community differed among 

nonmining sites and mining sites (fig. 8). Mining sites 

tended to contain a larger percentage of the more 

tolerant taxa than the nonmining sites. Except for the 

Baker site, nonmining sites tend to have a larger 

percentage of the more sensitive EPT taxa than the 

mining sites. The taxa at the Baker site consisted of 

approximately 50 percent Diptera (true flies) species, 

but 48.5 percent of the Diptera at this site consisted of 

one family of Simuliidae (black flies). Clements 

(1994) noted that the distribution of Simuliidae (black 

flies) was probably more affected by factors such as 

seasonal fluctuations in temperature and food availability than water-quality factors.

Decreased total abundance and species richness 

and changes in macroinvertebrate predominant groups 

commonly occur in aquatic systems affected by trace 

elements (Rosenberg and Resh, 1993). Total abundance, taxa richness, and EPT taxa richness (table 11) 

were significantly different (p < 0.05) between 

nonmining and mining sites. Total abundance of 

macroinvertebrates was approximately two to eight 

times higher at nonmining sites than at mining sites 

(table 11 and Appendix G). Total taxa and EPT taxa 

richness (fig. 8 and table 11) also indicated differences 

in macroinvertebrate composition between nonmining 

and mining sites. Taxa and EPT taxa richness was 

expected to decrease with increased perturbation at a 

site (Barbour and others, 1997). Taxa richness almost 

doubled between site types, ranging from 30 to 45 

species at nonmining sites and 17 to 26 species at 

mining sites. The number of EPT taxa ranged from 

18 to 31 species at nonmining sites and 1 to 13 species 

at mining sites.
26 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Table 9. Classification ranking of U.S. Environmental Protection Agency’s Rapid Bioassessment Protocols (Barbou1997) habitat parameters for nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98 [ %, percent; m, meters; >, greater than; <, less than] 

Habitat parameters

RBP*

habitat 

category1

Instream 

cover2

(% submerged 

habitat) 

Epifaunal 

substrate3

(riffle quality) 

Embeddedness4

(% substrate 

surrounded by fine 

sediment) 

Channel 

alteration5

(% channelized 

stream reach) 

Sediment 

deposition6

(% recent deposition

Optimal (16

–20) >50 wide and long 0–25 minimal <5 

Suboptimal (11

–15) 30

–50 wide and short 25

–50 <40 5–30 

Marginal (6

–10) 10

–30 narrow and long 50

–75 40

–80 30

–50 

Poor (0

–5) <10 narrow and short >75 >80 >50 

Habitat parameters 

RBP*

habitat 

category1

Channel flow 

status8

(% substrate 

exposed) 

Bank vegetation 

protection9

(% vegetative cover) 

Bank 

stability10

(erosion of 

streambanks) 

Riparian 

vegetative zone 

width11

(m) 

RBP*site 

score range12

Optimal (16

–20) minimal >90 stable >18 200

–155 

Suboptimal (11

–15) <25 70

–90 moderately stable 12

–18 154

–102 

Marginal (6

–10) 25

–75 50

–70 moderately unstable 6–12 101

–49 

Poor (0

–5) >75 <50 unstable <6 48

–0 

*

RBP = Rapid Bioassessment Protocols include a visual-based habitat assessment for riffle/run-dominated streams, modified for use in this study (Barbour and others, 1997). 1 RBP habitat rank was based on a score ranging from 0 to 20 for each habitat parameter with the exception of bank vegetation protection, bank stability, and riparian vegetative zon

width, which were based on scores from 0 to 10 for the right streambank and scores from 0 to 10 for the left streambank. Numbers in parentheses represent the range of scores withieach category. 

2 Instream cover was based on the percentage of mix of submerged logs, undercut banks, or other stable habitat at the site. 3 Epifaunal substrate was based on the quality of riffles (riffle width compared to stream width and riffle length compared to stream width) at the site. 4 Embeddedness was based on the percentage of substrate surrounded by fine sediment at the site. 5 Channel alteration was based on the percentage of disrupted stream bottom and streambanks due to dredging, channelization, or other disruptive stream activities at the site. 6 Sediment deposition was based on the percentage of stream bottom affected by sediment deposition (enlargement of islands or point bars) at the site. 7 Frequency of riffles was based on the relative frequency of riffles and the distance between riffles compared to the stream width at a site. 8 Channel flow status was based on the percentage of substrate exposed at the site. 9 Bank vegetation protection was based on the percentage of vegetative cover on the streambank at the site. 

 10 Bank stability was based on the evidence of streambank erosion or bank failure and potential for future problems at the site.  11 Riparian vegetative zone width was the width of the riparian zone not affected by human activities at the site.  12 RBP site score ranges are the ranges that represent the sum of each habitat parameter score for a site; these ranges correspond to the RBP site habitat rating for the site.  13 RBP site habitat rating is the overall stream habitat rating for the site, based on the total score for the site; the score corresponds to the RBP site score range. 
BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE 27

Table 10. Habitat assessment results using U.S. Environmental Protection Agency’s Rapid Bioassessment Protocols (B1997) for nonmining and mining sites in the Upper Colorado River Basin, Colorado, 1997–98[ %, percent; m, meters; >, greater than; < less than]

Habitat parameters1

Site 

abbreviations

Instream 

cover 

(% submerged 

habitat) 

Epifaunal 

substrate 

(riffle quality) 

Embeddedness 

(% substrate 

surrounded by fine 

sediment) 

Channel 

alteration 

(% channelized 

stream reach) 

Sediment 

deposition 

(% recent deposition) 

(

NONMINING SITES 

Farncomb >50 wide and long 0–25 minimal <5 

Polk >50 wide and long 0–25 minimal <5 Baker >50 wide and long 0–25 minimal <5 

MINING SITES 

Red Mountain >50 wide and short 0–25 minimal 5–30 

Canyon >50 wide and long 0–25 <40 <5 

Ouray 10–30 wide and long 25–50 >80 <5 

Cutler 30–50 wide and long 25–50 <40 <5 Ridgway >50 wide and long 25–50 minimal 5–30 

Habitat parameters1

Site 

abbreviations

Channel flow 

status 

(% substrate 

exposed) 

Bank vegetation 

protection 

(% vegetation cover) 

Bank 

stability 

(erosion of 

streambanks) 

Riparian 

vegetative zone 

width 

(m) 

RBP* site 

score 

NONMINING SITES 

Farncomb minimal >90 stable >18 199 Polk minimal >90 stable >18 180 Baker minimal >90 moderately stable >18 179 

MINING SITES 

Red Mountain minimal >90 stable 12–18 164 

Canyon minimal >90 stable 12–18 180 Ouray minimal 50–70 moderately stable 6–12 128 Cutler minimal 50–70 moderately stable 6–12 146 Ridgway minimal >90 moderately stable 12–18 157 

 * RBP = Rapid Bioassessment Protocols include a visual-based habitat assessment for riffle/run-dominated streams, modified for use in this study (Barbour and others, 1997).  1 Habitat parameter descriptions are included in table 9.
28 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

0

20

40

60

80

100

Ephemeroptera

Plecoptera

Trichoptera

Coleoptera

Diptera

Non-insects

SITE ABBREVIATIONS

PERCENTAGE PREDOMINANT GROUPS

NONMINING MINING

EXPLANATION

EXPLANATION

0

5

10

15

20

25

30

35

40

45

50

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

Taxa richness

EPT richness

SITE ABBREVIATIONS

NUMBER OF TAXA

NONMINING MINING

Figure 8. Composition of predominant groups, taxa, and Ephemeroptera, Plecoptera, and Trichoptera (EPT) 

richness of macroinvertebrates from nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1997–98.
BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE 29

The Ephemeroptera family Baetidae (mayfly), 

primarily Baetis species, dominated most sites except 

the Baker site, which was dominated by the Diptera 

family Simuliidae (black flies), and the Red Mountain 

site, which was dominated by the Diptera family 

Chironomidae (midges), primarily Paraphaenocladius species. Mining sites were dominated by single 

species (30 percent or more), whereas nonmining sites 

were less dominated (less than 30 percent) by a single 

species except at the Baker site, where species in the 

family Simuliidae (black flies) composed 48.5 percent 

of the macroinvertebrate community. The ShannonWeaver diversity index (Ward and Kondratieff, 1992) 

log base 2 incorporates richness and evenness in a 

measure of general diversity and was significantly 

different (p < 0.05) between nonmining and mining 

sites (table 11). The Shannon-Weaver diversity ranged 

from 3.3 to 3.8 at nonmining sites and from 2.2 to 

3.3 at mining sites. Higher Shannon-Weaver diversity 

scores, as found at the nonmining sites, indicate that 

these sites have a more highly diverse assemblage of 

macroinvertebrates. In general, a large diversity in the 

macroinvertebrate community indicates water quality 

that has not been degraded (Barbour and others, 1997).

Functional feeding groups are another measure 

of the composition of the benthic macroinvertebrate 

community that provides information on the balance 

of feeding strategies in the community. An imbalance 

in functional feeding groups reflects stressed conditions. Specialist feeders, such as scrapers and shredders, usually represent the more sensitive taxa and may 

be abundant in healthy streams. Generalist feeders, 

such as collectors and filterers, have a broader range of 

acceptable food materials than do the specialist 

feeders and, therefore, are more tolerant to changes in 

trophic interaction, production, and food-source availability (Barbour and others, 1997).

With the exception of the Baker site, specialists 

dominated the nonmining sites, and generalists dominated all the mining sites in the study area. Specialists 

ranged from 13.6 to 54.7 percent of the sample at 

nonmining sites and from 3.6 to 13 percent of the 

sample for mining sites, whereas generalists ranged 

from 33.4 to 68.7 percent of the sample at nonmining 

sites and from 51.1 to 92.9 percent of the sample at 

mining sites. The ratio of specialist to generalist was 

significantly different (p < 0.05) between nonmining 

and mining sites and was used to indicate the differences between the site groups (fig. 9). Generalists are 

more tolerant and thus become numerically dominant 

in response to environmental stress (Rosenberg and 

Resh, 1993); therefore, the specialist-to-generalist 

ratio generally decreases with increasing perturbation 

at a site. All nonmining sites except the Baker site had 

ratios from four to six times higher than for mining 

sites. Because almost one-half of the macroinverteTable 11. Selected biotic metrics from nonmining and mining sites in the Upper Colorado River 

Basin, Colorado, 1997–98 

Biotic metric 

Site 

abbreviations 

Total 

abundance1

Taxa 

richness 

EPT2

richness 

Shannon-Weaver 

diversity index3

NONMINING SITES 

Farncomb 3,120 39 18 3.3 

Polk 1,840 30 18 3.8 

Baker 6,590 45 31 3.6 

MINING SITES 

Red Mountain 68 17 1 2.7 

Canyon 828 24 13 2.2 

Ouray 92 18 7 3.3 

Cutler 185 23 11 3.2 

Ridgway 457 26 11 2.8 

 1 Total abundance is based on number of organisms per square meter. 2 EPT: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies). 3 Shannon-Weaver diversity index is log base 2 (Ward and Kondratieff, 1992).
30 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

0.0

0.5

1.0

1.5

2.0

SITE ABBREVIATION

EXPLANATION

EXPLANATION

RATIO OF SPECIALIST TO GENERALIST

NONMINING MINING

0.0

0.5

1.0

1.5

2.0

SITE ABBREVIATION

NONMINING MINING

RATIO OF SPECIALIST TO GENERALIST

Specialist-to 

generalist

macroinvertebrate

ratio without

Simuliidae

Specialist-togeneralist

macroinvertebrate

ratio with

Simuliidae

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

-

Figure 9. Ratio of specialist to generalist macroinvertebrate species with and without Simuliidae from nonmining and 

mining sites in the Upper Colorado River Basin, Colorado, 1997–98.
BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE 31

brate community at the Baker site consisted of Simuliidae (black flies), primarily Prosimulium 

onychodactylum, which is classified as a generalist, 

the Baker site had a low specialist-to-generalist ratio. 

However, when Simuliidae (black flies) was removed 

from all the sites and the specialist-to-generalist ratio 

was recalculated, the Baker site had a ratio 2.5 times 

higher than for mining sites (fig. 9). Simuliids are 

commonly abundant at lower alpine-upper montane 

settings (Ward, 1986) such as the Baker site.

Community responses to trace elements 

measured in this study were similar to responses 

reported for other streams in Colorado (Ward, 1986; 

Clements, 1994, 1995; Clements and Kiffney, 1995). 

These studies indicated that careful examination of 

certain species of EPT and Chironomidae may be 

useful in distinguishing between sites affected by trace 

elements in the Rocky Mountain region. The abundance of mayflies, stoneflies, and caddisflies and the 

percentage of Diptera subfamily Orthocladiinae 

(orthoclad midges) to the family Chironomidae 

(midges) were compared to determine differences 

between nonmining and mining sites. A complete list 

of benthic macroinvertebrate data for this study is 

given in Appendix G. In this study, benthic macroinvertebrate density was based on a 1-m2 area and was 

obtained by dividing the number of organisms 

collected by the surface area of the sampler.

Ephemeroptera (mayflies)

Mayfly abundance and richness have been used 

as indicators of elevated trace-element concentrations 

in stream water. Low mayfly abundance and richness 

as reported by Winner and others (1980), Clements 

(1994), and Clements and Kiffney (1995) may be 

related to increases in trace-element concentrations. 

Winner and others (1980) stated that mayflies were 

present only at the least polluted sites and that 

mayflies and caddisflies were very sensitive to copper 

and zinc pollution. Mayfly abundance was at least 

2 times higher at the nonmining sites compared to the 

mining sites in this study (fig. 10). Mayfly abundance 

ranged from 1,128 to 1,973 individuals at the 

nonmining sites and from 0 to 573 individuals at the 

mining sites. Mayfly richness ranged from 7 species at 

the Farncomb site to 14 species at the Baker site 

(nonmining sites) and from 0 species at the Red 

Mountain site to 4 species at the Canyon site (mining 

sites).

One genus of mayfly, Baetis, is considered by 

some stream ecologists to be more tolerant than other 

mayfly taxa, such as the family Heptageniidae (Clements and Kiffney, 1995). The abundance of Baetis sp. 

was plotted against the total mayfly abundance at each 

site (fig. 10). The number of Baetis sp. ranged from 

506 to 710 individuals (33.2 to 44.8 percent of the total 

mayfly community by site) at nonmining sites and 

from 144 to 530 individuals (72 to 94.4 percent of the 

total mayfly community by site) at mining sites that 

had mayflies. The predominance of Baetis sp. in the 

mayfly community at mining sites and a decrease in 

the total mayfly community at mining sites indicates 

that Baetis sp. may be more tolerant of elevated traceelement concentrations than other mayflies.

Clements and Kiffney (1995) determined that 

the total abundance and species richness of mayflies 

and the abundance of Heptageniidae (mayflies) were 

the most reliable indicators of the effects of trace 

elements in southern Rocky Mountain streams. The 

abundance of the mayfly family Heptageniidae was 

compared to the total mayfly abundance at each site 

(fig. 10). The number of Heptageniidae ranged from 

330 to 1,263 individuals (20.5 to 64 percent of the total 

mayfly community by site) at nonmining sites and 

from 0 to 25.6 individuals (0 to 4.5 percent of the total 

mayfly community by site) at mining sites. The 

predominance of Heptageniidae within the mayfly 

community at nonmining sites and the decrease in the 

overall mayfly community at mining sites indicated 

that the Heptageniid mayflies may be more sensitive to 

elevated trace-element concentrations than other 

mayflies.

Plecoptera (stoneflies)

Stonefly populations, like mayfly abundance 

and richness, have been used to indicate elevated 

trace-element concentrations in stream water. Ward 

(1986) and Clements and Kiffney (1995) stated that 

temperature and changes in elevation may more 

strongly affect stonefly populations than mayflies or 

caddisflies. Ward (1986) stated that certain abundant 

stoneflies may be missing entirely during summer 

sampling because these species mature and emerge 

well before maximum stream temperatures are 

attained. Therefore, stonefly populations should be
32 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

SITE ABBREVIATION

SITE ABBREVIATION

PLECOPTERA AND CHLOROPERLIDAE ABUNDANCE

EPHEMEROPTERA AND  SPECIES ABUNDANCE

BAETIS

0

500

1,000

1,500

2,000

2,500

0

500

1,000

1,500

2,000

2,500

0

200

400

600

800

1,000

1,200

EPHEMEROPTERA AND HEPTAGENIIDAE  ABUNDANCE

NONMINING MINING

NONMINING

NONMINING MINING

MINING

Mayfly

EXPLANATION

EXPLANATION

EXPLANATION

Mayfly

Stonefly

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

SITE ABBREVIATION

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

Ephemeroptera

Heptageniidae

Plecoptera 

Chloroperlidae

Ephemeroptera

Baetis sp.

Figure 10. Abundance of selected mayfly and stonefly taxa from nonmining and mining sites in the Upper Colorado 

River Basin, Colorado, 1997–98.
BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE 33

used with caution when large temperature or elevation, 

or both temperature and elevation, differences occur 

between sites. Clements (1995) reported that stoneflies 

are moderately tolerant of low levels of trace elements 

and are commonly one of the earlier groups to recover 

after influxes of trace elements.

Stonefly abundance was almost two to five 

times higher at the nonmining sites than at the mining 

sites (fig. 10). Stonefly abundance ranged from 334 to 

1,030 individuals at the nonmining sites and from 

0.8 to 176 individuals at the mining sites. Stonefly 

richness ranged from 6 species at the Polk site to 

11 species at the Baker site (nonmining sites) and from 

1 species at the Red Mountain site to 6 species at the 

Canyon site (mining sites).

Abundance patterns of the Chloroperlidae 

family of stoneflies indicated that this group was 

sensitive to moderate zinc concentrations and may be a 

useful indicator of elevated trace-element concentrations in southern Rocky Mountain streams (Clements 

and Kiffney, 1995). The abundance of Chloroperlidae 

was plotted against the total stonefly abundance at 

each site (fig. 10). Chloroperlidae abundance at 

nonmining sites was greater than at mining sites. The 

number of Chloroperlidae ranged from 125 to 

539 individuals (29.1 to 52.3 percent of the total 

stonefly community by site) at nonmining sites and 

from 0 to 92.8 individuals (0 to 79.4 percent of the 

total stonefly community by site) at mining sites. The 

predominance of Chloroperlidae in the stonefly 

community at nonmining sites compared to mining 

sites indicates that these macroinvertebrates may be 

more sensitive to elevated trace-element concentrations than other stoneflies.

Trichoptera (caddisflies)

Caddisfly abundance and richness have been 

used as indicators of elevated trace-element concentrations in stream water. Generally, low caddisfly abundance and richness, as reported by Winner and others 

(1980), Clements (1994), and Clements and Kiffney 

(1995), may be related to increases in trace-element 

concentrations. Winner and others (1980) concluded 

that caddisflies were numerically important at the 

moderately impaired sites and that caddisflies and 

mayflies were very sensitive to copper and zinc.

Except for the Farncomb site, caddisfly abundance was from three to five times higher at the 

nonmining sites compared to the mining sites (fig. 11). 

Caddisfly abundance ranged from 33.6 to 334 individuals at the nonmining sites and from 0 to 61.6 individuals at the mining sites. Caddisfly richness ranged 

from 4 species at the Farncomb and Polk sites to 

6 species at the Baker site (nonmining sites) and from 

0 species at the Red Mountain site to 5 species at the 

Ridgway site (mining sites). The caddisfly abundance 

patterns indicated that this taxon may have recovered 

at the Ridgway site, where abundance is almost twice 

that of any other mining site, and that the richness is 

comparable to that at nonmining sites.

Rhyacophila sp. (caddisfly) abundance data for 

this study were comparable to the study by Clements 

and Kiffney (1995), where the highest Rhyacophila sp. 

abundances were at nonmining sites and the lowest 

were at mining sites. The abundance of Rhyacophila

sp. was compared to the total caddisfly abundance at 

each site (fig. 11). The number of Rhyacophila sp. 

ranged from 26.4 to 195 individuals (17.5 to 

97.6 percent of the total caddisfly community by site) 

at nonmining sites and from 0 to 8.8 individuals (0 to 

35.7 percent of the total caddisfly community by site) 

at mining sites. Rhyacophila sp. was totally absent at 

three of five mining sites and was numerically limited 

at the Canyon and Ouray sites. The predominance of 

Rhyacophila sp. in the caddisfly community at 

nonmining sites and a decrease in the community at 

mining sites indicated that these cadddisflies may be 

more sensitive to elevated trace-element concentrations than other caddisflies.

In contrast, one family of net-spinning caddisflies, Hydropsychidae, was abundant at mining sites. 

Hydropsychidae abundance patterns for this study 

were similar to patterns in Clements and Kiffney's 

(1995) study, where Hydropsychidae relative abundance increased at mining sites and was lowest at 

nonmining sites. The abundance of Hydropsychidae 

was plotted against the total caddisfly abundance at 

each site (fig. 11). Numbers of Hydropsychidae ranged 

from 0 to 55.2 individuals (0 to 16.5 percent of the 

total caddisfly community by site) at nonmining sites 

and from 0 to 25.6 individuals (0 to 74.4 percent of the 

total caddisfly community by site) at mining sites. The 

predominance of Hydropsychidae in the caddisfly 

community at mining sites relative to nonmining sites 

indicates that Hydropsychid caddisflies may be more 

tolerant of elevated trace-element concentrations than 

other caddisflies.
34 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

 Trichoptera 

 Rhyacophila sp.

SITE ABBREVIATION

SITE ABBREVIATION

SITE ABBREVIATION

CHIRONOMIDAE AND ORTHOCLADIINAE, IN PERCENT

TRICHOPTERA AND 

 SPECIES ABUNDANCE

RHYACOPHILA

 Trichoptera 

 Hy

Chironomidae

Orthocladiinae

dropsychidae 

TRICHOPTERA AND HYDROPSYCHIDAE  ABUNDANCE

0

50

100

150

200

250

300

350

400

0

50

100

150

200

250

300

350

400

0

10

20

30

40

50

60

70

80

90

100

NONMINING MINING

NONMINING

NONMINING

MINING

MINING

Caddisfly

EXPLANATION

EXPLANATION

EXPLANATION

Caddisfly

Midges

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

FARNCOMB POLK BAKER RED 

 MOUNTAIN

CANYON OURAY CUTLER RIDGWAY

Figure 11. Abundance and percentage of selected caddisfly and midge taxa from nonmining and mining sites in the 

Upper Colorado River Basin, Colorado, 1997–98.
BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE 35

Chironomidae (midges) 

The abundance and richness of Chironomidae 

(midges) have also been used as indicators of elevated 

trace-element concentrations in stream water. Generally, increased chironomid abundance and richness, as 

reported by Winner and others (1980), Clements 

(1994), and Clements and Kiffney (1995), may be 

related to increased trace-element concentrations. 

Winner and others (1980) concluded that a large 

number of chironomid species may tolerate long-term 

exposure to increased concentrations of multiple trace 

elements that would otherwise eliminate most other 

insect species.

Chironomid species, with some exceptions, tend 

to be widely distributed along the elevation gradient 

rather than being confined to zones (Ward, 1986). 

Because chironomids were present at all sites in 

different proportions, a percentage of chironomids was 

used instead of abundance to compare sites in the 

study area. Percentage of chironomid species ranged 

from 0.41 to 5.6 percent of the total macroinvertebrate 

community at the nonmining sites and from 5.0 to 

92.9 percent of the total macroinvertebrate community 

at the mining sites (fig. 11). Chironomid richness 

ranged from 5 (Baker site) to 13 species (Farncomb 

site) at the nonmining sites and from 7 (Ouray and 

Cutler sites) to 12 species (Red Mountain site) at the 

mining sites.

Previous work indicated that the Diptera 

subfamily Orthocladiinae chironomids (orthoclad 

midges) are highly tolerant of trace elements and are 

common in streams containing high concentrations of 

trace elements (Clements, 1995). Orthocladiinae 

chironomids in this study include: Brillia, Cardiocladius, Cricotopus/Orthocladius, Eukiefferiella, Metriocnemus fuscipes group, Paraphaenocladius, 

Parorthocladius, Rheocricotopus, Thienemanniella, 

and Tvetenia species (Appendix G). The percentage of 

orthoclads was compared to the total percentage of 

chironomids at each site (fig. 11). Orthoclads constituted 0.39 to 2.5 percent of the total macroinvertebrate 

community by site at nonmining sites and 2.9 to 61 

percent of the total macroinvertebrate community by 

site at mining sites. Orthoclads were highly abundant, 

especially at the Red Mountain site, where orthoclads 

constituted more than 61 percent of the entire macroinvertebrate community. The predominance of orthoclads in the macroinvertebrate community at mining 

sites and a limited number in the community at 

nonmining sites indicated that othoclad midges may 

be more tolerant to elevated trace-element concentrations than other chironomids.

Natural and Human-Related Factors

A first step in understanding how benthic 

macroinvertebrate communities are related to water 

and sediment quality is to identify the primary factors 

affecting macroinvertebrate communities in a drainage 

basin. Five major classes of environmental factors that 

affect the structure and function of the stream benthic 

community are (1) chemical water quality, (2) hydrodynamics, (3) instream and riparian habitat, (4) energy 

source, and (5) biological interactions (Hambrook and 

others, 1997). Important chemical water-quality 

factors include pH, temperature, alkalinity, turbidity, 

hardness, chemical solubility of trace elements, nutrients, organic compounds, and dissolved oxygen. 

Hydrodynamic factors include precipitation, stream 

velocity and discharge, high-low water extremes, and 

other watershed characteristics. Habitat characteristics that affect communities include instream habitat, 

channel morphology, and riparian and bank structure. 

Also, energy sources such as organic matter, sunlight, 

nutrient availability, primary and secondary production, and seasonal patterns as well as biological interactions such as feeding, competition, predation, 

parasitism, reproduction, and disease can affect the 

community structure (Hambrook and others, 1997).

The spatial and temporal patterns of stream 

temperature are extremely important in structuring 

aquatic insect communities. The thermal regime 

affects distribution patterns, life-cycle phenomena, 

trophic relations, and behavioral responses of aquatic 

insects (Ward and Stanford, 1982). Thermal effects 

may account for some variation in the macroinvertebrates between nonmining and mining sites. Ward 

(1986) and Clements and Kiffney (1995) found that 

temperature and elevation have a greater effect on 

stonefly populations than on mayflies or caddisflies. In 

this study, organic inputs (dissolved organic carbon) 

tended to be much higher at nonmining sites than at 

mining sites, which may affect the macroinvertebrate 

feeding strategies and composition at mining sites. 

Oxidized conditions and the availability of large 

sources of dissolved trace elements (often due to low 

pH, as at the Red Mountain and Ouray sites) may 

cause aluminum, iron, manganese, and, to a lesser 
36 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

extent, arsenic and copper to precipitate from the 

water (Hem, 1992). Low pH may alter the benthic 

macroinvertebrate community by (1) increasing stress 

to aquatic insects and other organisms, (2) blanketing 

the substrate with iron hydroxide and other metal 

precipitates, and (3) increasing trace-element solubility and toxicity, which are normally highest under 

acidic conditions (Ward and Kondratieff, 1992). 

Precipitates blanket the substrate at the Red Mountain 

(iron hydroxides) and Ouray (aluminum and iron 

hydroxides) sites. Precipitation of iron and manganese 

also may clog the filtering apparatus of filter feeders 

(Couillard and others, 1989). Taxa and EPT richness, 

as well as total abundance of macroinvertebrates, is the 

lowest at the Red Mountain and Ouray sites. The 

Ouray site seems to be affected by a combination of 

trace-element-enriched water inflows, predominantly 

from the Red Mountain site and, to a lesser extent, the 

Canyon site.

Human-related factors as well as environmental 

factors can influence macroinvertebrate communities 

at a site. Human-related factors such as land-use and 

water-use practices that affect water quality and quantity and stream habitat features may ultimately limit 

the production of macroinvertebrate communities and 

should be considered when comparing macroinvertebrate communities between nonmining and mining 

sites. Consistent biological sampling procedures 

should eliminate most variability associated with 

certain factors, including stream velocities, high-low 

water extremes, and seasonal effects. Other factors that 

seem to be important in this study include pH, chemical solubility of trace elements, stream temperature, 

stream elevation, organic inputs, basin geology, and 

stream habitat at a site. Stream habitat conditions were 

suitable for macroinvertebrates at all sites. Although 

high concentrations of some trace elements may occur 

naturally, trace-element concentrations at mining sites 

were much higher. High trace-element concentrations 

appear to affect the macroinvertebrate communities 

more than the other factors at these sites.

COMPARISON OF WATER QUALITY TO 

BIOLOGICAL CONDITIONS

A comparison of physical and chemical waterquality characteristics to biological conditions was 

conducted using a Water Quality Score (WQS) and a 

Biological Condition Score (BCS) (Plafkin and others, 

1989). A scattergram diagram comparison of the WQS 

to the BCS at the sampled sites is shown in figure 12. 

In general, as the WQS’s increased, the BCS’s also

Figure 12. Relation between water-quality scores (developed in this study) and biological condition scores and 

biological condition categories (Plafkin and others, 1989) for nonmining and mining sites in the Upper Colorado 

River Basin, Colorado, 1997–98.

Polk

Farncomb

Baker

NONMINING SITES

EXPLANATION

Ridgway

Red Mountain

Ouray

Cutler

Canyon

MINING SITES

5

10

15

20

25

30

35

40

5 10 15 20 25 30 35 40 45

WATER-QUALITY SCORE

BIOLOGICAL CONDITION SCORE AND BIOLOGICAL CONDITION CATEGORY 

MINING 

 SITES

NONMINING 

 SITES

SEVERELY

IMPAIRED

MODERATELY

IMPAIRED

SLIGHTLY

IMPAIRED

NONIMPAIRED
SUMMARY AND CONCLUSIONS 37

increased. Nonmining sites had higher WQS’s and 

BCS’s than mining sites. These scores were used to 

help identify relations between water-quality parameters (specific conductance, suspended sediment, 

dissolved organic carbon, dissolved sulfate, and 

dissolved zinc) that generally reflected trace-element 

chemistry in natural water and biotic metrics that 

describe the health of a macroinvertebrate community 

at a sampling site.

The comparison of nonmining and mining sites 

in figure 12 shows the differences between water 

quality and biological conditions of sites in the study. 

Water-quality scores ranged from 33.5 to 36.5 with a 

mean of 35 for nonmining sites and from 9 to 21 with 

a mean of 15 for mining sites. The mean BCS was 44 

for the nonmining sites and 18 for the mining sites. 

The BCS categorized the nonmining sites as nonimpaired, and the mining sites were categorized as 

moderately impaired. Based on a critical review of 

habitat assessment and physiochemical data at these 

sites, the Red Mountain and Cutler sites are better 

represented in the severely impaired and slightly 

impaired categories, respectively. Although the 

Canyon site was categorized by the BCS as moderately impaired, this site had optimal habitat characterization and generally had better individual biotic 

metric results than the other mining sites. The Canyon 

site had a high percentage of one predominant taxon, 

which placed this site into a lower BCS category.

SUMMARY AND CONCLUSIONS

Intensive mining activity and highly mineralized 

rock formations have had significant impacts on 

surface-water and streambed-sediment quality and 

aquatic life within the upper reaches of the 

Uncompahgre River in western Colorado. A synoptic 

study by the U.S. Geological Survey National WaterQuality Assessment Program was completed in the 

upper Uncompahgre River Basin in 1998 to better 

understand the relations of trace elements (with 

emphasis on aluminum, arsenic, copper, iron, lead, and 

zinc concentrations) in water, streambed sediment, and 

aquatic life. Water-chemistry, streambed-sediment, 

and benthic macroinvertebrate samples were collected 

during low-flow conditions between October 1995 and 

July 1998 at five sites on the upper Uncompahgre 

River, all downstream from historical mining, and at 

three sites in drainage basins in the Upper Colorado 

River Basin where mining has not occurred. Aquatic 

bryophytes were transplanted to all sites for 15 days of 

exposure to the water column during which time field 

parameters were measured and chemical water-quality 

and benthic macroinvertebrate samples were collected. 

Stream habitat characteristics also were documented at 

each site.

Seventeen trace elements were analyzed in the 

water-column samples, 24 trace elements in streambed-sediment samples, and 19 trace elements in transplanted bryophytes. Many trace-element concentrations in the water column were near or less than the 

minimum reporting level or indicated little variation 

across the study area. Six trace elements—aluminum, 

arsenic, copper, iron, lead, and zinc—were selected for 

discussion in this study because they (1) were 

frequently detected in most water, streambed sediment, and transplanted bryophyte samples, (2) showed 

some variability in concentrations, and (3) have 

aquatic-life standards or water-quality guidelines associated with them.

Concentrations of aluminum, copper, iron, lead, 

and zinc in the water column were significantly 

different (p < 0.05) between nonmining and mining 

sites for all total concentrations and most dissolved 

concentrations. Concentrations of trace elements at 

mining sites exceeded Colorado acute aquatic-life 

standards for aluminum, copper, and zinc and chronic 

aquatic-life standards for aluminum, copper, iron, 

lead, and zinc.

Concentrations of copper, lead, and zinc in 

streambed sediment were significantly different 

(p < 0.05) between nonmining and mining sites. 

Streambed-sediment concentrations of arsenic, copper, 

lead, and zinc at some nonmining sites were above the 

interim freshwater sediment-quality guidelines (ISQG) 

developed in the Canadian Sediment Quality Guidelines. Concentrations at most mining sites and one 

nonmining site exceeded the Canadian sedimentquality guidelines probable effect level (PEL) for 

arsenic, lead, and zinc. Concentrations of copper and 

zinc were below the PEL at two mining sites.

Concentrations of trace elements in samples of 

transplanted bryophytes from all sites in the study area 

are a function of adsorption and absorption processes. 

Transplanted bryophyte concentrations of arsenic, 

copper, iron, and lead in transplanted bryophytes were 

significantly different (p < 0.05) among nonmining 

and mining sites. The relative ranking of trace-element 

bioconcentration by transplanted bryophytes was lead 
38 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

> copper > zinc > arsenic > iron > aluminum, which 

indicates that the bryophytes tended to favor the accumulation of lead, copper, and zinc more than arsenic, 

iron, and aluminum. When one-half of the minimum 

reporting level was used for concentrations of 

dissolved arsenic, copper, iron, lead, and zinc in the 

water that were below the reporting level, bioconcentration factors (15-day exposure period) for the transplanted bryophytes were significantly different 

(p < 0.05) for arsenic, lead, and zinc at nonmining sites 

compared to mining sites.

Relations between concentrations of trace 

elements in different sampling media (water column, 

streambed sediment, and transplanted bryophytes) 

were examined. In general, concentrations of trace 

elements in streambed sediment and transplanted 

bryophytes tended to be more closely correlated with 

each other than either of them were with concentrations in the water column. Also, concentrations of 

aluminum, copper, iron, lead, and zinc in bryophytes 

may be useful to the estimation of concentrations of 

these constituents in streambed sediment. 

Stream habitat was rated as optimal to suboptimal using the RBP habitat characterization for all 

sites in the study area. Generally, stream habitat conditions were similar among nonmining and mining sites 

and were suitable for macroinvertebrate communities. 

All study sites except the Ouray and Cutler sites were 

rated as having optimal habitat for biological communities. The Ouray and Cutler sites were rated as suboptimal because of disturbances in the stream habitat.

Generally, the benthic macroinvertebrate 

community composition at nonmining sites and 

mining sites differed. Mining sites had significantly 

lower total abundance, decreased taxa and EPT richness, and a larger percentage of tolerant species of 

benthic macroinvertebrates than did nonmining sites. 

The predominance of Baetis sp. (mayflies) and 

Hydropsychidae (caddisflies) and the large percentage 

of Orthocladiinae chironomids (midges) at mining 

sites indicated that these macroinvertebrates may be 

tolerant of elevated trace-element concentrations. The 

scarcity of Heptageniidae (mayflies), Chloroperlidae 

(stoneflies), and Rhyacophila sp. (caddisflies) at 

mining sites indicates that these macroinvertebrates 

may be sensitive to elevated trace-element concentrations. Also, mayfly, stonefly, and caddisfly abundance 

as well as the large percentage of chironomids were 

indicators of mining effects at sites in the study area.

Although high concentrations of some trace 

elements may occur naturally, trace-element concentrations at mining sites tend to be much higher because 

of the combination of natural and human-related 

inputs. The combined natural and human-related traceelement effects may degrade the biological communities at these sites. Mining land-use practices may 

increase the potential for biological impairment in the 

study area as a result of increased acidity; precipitation 

of iron, aluminum, and other hydroxides; and 

increased trace-element availability and toxicity 

resulting from acidic conditions. Oxidized conditions 

and the availability of large sources of dissolved trace 

elements due to low pH, as at the Red Mountain and 

Ouray sites, may cause iron, aluminum, manganese, 

and to a lesser extent, arsenic and copper to precipitate 

from the water. Precipitates blanket the substrate at the 

Red Mountain (iron hydroxides) and Ouray 

(aluminum and iron hydroxides) sites. Taxa richness, 

EPT richness, and total abundance of macroinvertebrates were the lowest at the Red Mountain and Ouray 

sites. 

Comparison of field parameters and chemical 

water-quality characteristics to biological conditions 

was conducted using a water quality score (WQS) and 

a biological condition score. In general, as the WQS 

increased, the BCS also increased. Nonmining sites 

had higher WQS’s and BCS’s than mining sites. The 

BCS categorized the nonmining sites as nonimpaired, 

and the mining sites were categorized as slightly to 

severely impaired. Other important factors in this 

study that influenced surface-water quality include 

stream pH, chemical solubility of trace elements, 

stream temperature, stream elevation, organic inputs 

into the stream, basin geology, and stream habitat at a 

site. Although high concentrations of some trace 

elements may occur naturally, trace-element concentrations at mining sites were much higher. High traceelement concentrations appear to affect the macroinvertebrate communities more than the other factors 

at these sites. Mayfly, stonefly, and caddisfly abundance and the percentage of midge species are good 

indicators of mining effects at sites in the study area.

In this study, the combination of multiple 

sampling media (water chemistry, streambed sediment, and benthic macroinvertebrates), as well as 

transplanted bryophyte data and stream habitat characterization, provided evidence that trace-element 

factors were controlling the biological communities at 

study sites. Water-chemistry and streambed-sediment 
REFERENCES CITED 39

data defined trace-element sources in the stream 

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available for uptake by macroinvertebrates and other 

organisms. Benthic macroinvertebrates provided a 

measure of stream ecosystem health, which was 

compared between nonmining and mining sites. The 

collection of water-quality and stream-habitat data in 

conjunction with the biological sampling helped identify stream reaches that were influenced by natural and 

human-related factors.

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APPENDIX
APPENDIX 45

Appendix A. Surface-water-quality field measurement constituents and minimum reporting 

levels for samples collected from selected sites in the study area 

[mg/L, milligrams per liter; NA, not applicable; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms 

per liter] 

Constituent Reported as Minimum reporting level 

Laboratory and field measurements

Acid-neutralizing capacity mg/L CaCO3 NA 

Alkalinity mg/L CaCO3 NA 

Dissolved oxygen mg/L NA 

pH standard units NA 

Specific conductance μS/cm at 25 degrees Celsius NA 

Suspended sediment mg/L NA 

Temperature degrees Celsius NA 

Calculated constituents 

Bicarbonate mg/L as HCO3 NA 

Dissolved solids mg/L NA 

Hardness mg/L as CaCO3 NA 

Major ions 

 (sample filtered through 0.45-micrometer filter) 

Calcium mg/L as Ca 0.02 mg/L 

Chloride mg/L as Cl 0.1 mg/L 

Fluoride mg/L as F 0.1 mg/L 

Magnesium mg/L as Mg 0.01mg/L 

Potassium mg/L as K 0.1 mg/L 

Silica mg/L as SiO2 0.01 mg/L 

Sodium mg/L as Na 0.2 mg/L 

Sulfate mg/L as SO4 0.1 mg/L 

Trace elements 

 (sample filtered through 0.45-micrometer filter) 

Aluminum μg/L as Al 1 μg/L 

Antimony μg/L as Sb 1 μg/L 

Arsenic μg/L as As 1 μg/L 

Barium μg/L as Ba 1 μg/L 

Beryllium μg/L as Be 1 μg/L 

Cadmium μg/L as Cd 1 μg/L 

Chromium μg/L as Cr 1 μg/L 

Cobalt μg/L as Co 1 μg/L 

Copper μg/L as Cu 1 μg/L 

Iron μg/L as Fe 3 μg/L 

Lead μg/L as Pb 1 μg/L 

Manganese μg/L as Mn 1 μg/L 

Molybdenum μg/L as Mo 1 μg/L 

Nickel μg/L as Ni 1 μg/L 

Silver μg/L as Ag 1 μg/L 

Uranium μg/L as U 1 μg/L 

Zinc μg/L as Zn 1 μg/L 

Organics 

 (sample filtered through 0.45-micrometer filter) 

Dissolved organic carbon mg/L as C 0.1 mg/L 

Suspended organic carbon mg/L as C 0.2 mg/L 
46 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Appendix B. Streambed-sediment constituents and minimum reporting levels for samples 

collected from selected sites in the study area 

[μg/g, micrograms per gram, dry weight; %, percent; <, less than] 

Constituent Reported as Minimum reporting level 

Trace elements

 (sample <63-micrometer fraction) 

Aluminum percent weight as Al 0.005% 

Antimony μg/g as Sb 0.1 μg/g

Arsenic μg/g as As 0.1 μg/g

Barium μg/g as Ba 1 μg/g

Beryllium μg/g as Be 1 μg/g

Cadmium μg/g as Cd 0.1 μg/g

Chromium μg/g as Cr 1 μg/g

Cobalt μg/g as Co 1 μg/g

Copper μg/g as Cu 1 μg/g

Iron percent weight as Fe 0.005% 

Lead μg/g as Pb 4 μg/g

Lithium μg/g as Li 2 μg/g

Manganese μg/g as Mn 4 μg/g

Mercury μg/g as Hg 0.02 μg/g

Molybdenum μg/g as Mo 2 μg/g

Nickel μg/g as Ni 2 μg/g

Selenium μg/g as Se 0.1 μg/g

Silver μg/g as Ag 0.1 μg/g

Strontium μg/g as Sr 2 μg/g

Thallium μg/g as Tl 50 μg/g

Titanium percent weight as Ti 0.005% 

Uranium μg/g as U 0.05 μg/g

Vanadium μg/g as V 2 μg/g

Zinc μg/g as Zn 4 μg/g

Organics 

 (sample <63-micrometer fraction) 

Carbon, organic percent weight as C 0.01% 
APPENDIX 47

Appendix C. Transplanted bryophyte constituents and minimum reporting levels for samples 

collected from selected sites in the study area 

[μg/g, micrograms per gram-dry weight] 

Constituent Reported as Minimum reporting limit 

Trace elements

 (sample bryophyte tissue) 

Aluminum μg/g as Al 5.0 μg/g

Arsenic μg/g as As 0.5 μg/g

Barium μg/g as Ba 1.0 μg/g

Beryllium μg/g as Be 0.1 μg/g

Boron μg/g as B 2.0 μg/g

Cadmium μg/g as Cd 0.1 μg/g

Chromium μg/g as Cr 0.5 μg/g

Copper μg/g as Cu 0.5 μg/g

Iron μg/g as Fe 5.0 μg/g

Lead μg/g as Pb 0.5 μg/g

Magnesium μg/g as Mg 5 .0μg/g

Manganese μg/g as Mn 1 .0μg/g

Mercury μg/g as Hg 0.2 μg/g

Molybdenum μg/g as Mo 2.0 μg/g

Nickel μg/g as Ni 0.5 μg/g

Selenium μg/g as Se 0.5 μg/g

Strontium μg/g as Sr 0.5 μg/g

Vanadium μg/g as V 0.5 μg/g

Zinc μg/g as Zn 1.0 μg/g
48 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98 Appendix D. Selected water-column data for samples collected from nonmining and mining sites in the Upper Colorado 

Basin, Colorado, 1997–98 [--, no data; ft, feet; oC, degrees Celsius; ft3/s, cubic feet per second; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micro

CaCO3, calcium carbonate,; <, less than; lab, laboratory] Site Site abbreviation Station number Date Time Width (ft) Discharge (ft3/s) Acid-neutralizing capacity (mg/L as CaCO3) Alkalinity, field (mg/L as CaCO3) D

NONMINING SITES French Gulch above Farncomb Hill near Farncomb 3928381055729 07/29/97 0810 13 13.4 27 24 

Polk Creek at Interstate Highway 70 near Vail, CO Polk 3935271061435 08/04/98 0845 4.0 6.6 50 47 Colorado River below Baker Gulch near Granby, Baker 09010500 08/10/98 1250 34 43 27 25 

MINING SITES Red Mountain Creek above Crystal Lake near Red Mountain 3757321073940 07/22/97 0800 24 52.4 0 0 

Canyon Creek below Squaw Gulch near Ouray, CO Canyon 3800071074136 07/22/97 1400 37 170 29 27 Uncompahgre River at Ouray, CO Ouray 3801151074020 07/23/97 0725 -- 260 12 11 Uncompahgre River above Cutler Creek near Cutler 3804481074208 07/23/97 0945 43 294 19 18 Uncompahgre River near Ridgway, CO Ridgway 09146200 07/23/97 1245 43 379 70 69 

Site abbreviation Specific conductance, lab 

(μS/cm) 

Specific 

conductance, field 

(μS/cm) 

Temperature 

(

oC) 

Bicarbonate 

(mg/L as 

HCO3)

Dissolved 

solids 

(mg/L) 

Hardness 

(mg/L as 

CaCO3) 

Calcium 

(mg/L) 

Magnesium 

(mg/L) 

Sodium 

(mg/L) 

Potass

(mg/

NONMINING SITES 

 Farncomb 79 72 4.9 29 44 34 12 0.9 1.0 0.4  Polk 99 94 6.8 57 53 45 12 3.5 1.6 0.4  Baker 65 62 14 31 39 27 7.7 1.8 1.9 0.8 

MINING SITES 

 Red 446 415 6.4 0 264 120 42.8 3.2 1.4 0.5  Canyon 162 161 9.9 33 89 70 26.1 1.2 1.6 0.3  Ouray 193 194 8.5 13 111 80 28.9 1.7 2.0 0.4  Cutler 221 222 10 22 129 93 33.9 1.9 3.0 0.5  Ridgway 398 400 15 84 242 170 58.8 6.7 9.4 1.1 
APPENDIX 49

Appendix D. Selected water-column data for samples collected from nonmining and mining sites in the Upper Colorado R

Colorado, 1997–98—Continued 

Site 

abbreviation 

Fluoride 

(mg/L) 

Silica 

 (mg/L) 

Aluminum, 

dissolved 

(μg/L) 

Aluminum, 

total 

(μg/L) 

Antimony,

dissolved 

(μg/L) 

Arsenic, 

dissolved 

(μg/L) 

Barium, 

dissolved 

(μg/L) 

Beryllium,

dissolved 

(μg/L) 

Cadmium, 

dissolved 

(μg/L) 

Cadmium, 

total 

(μg/L) 

Chromium, 

dissolved 

(μg/L) 

Cobalt, 

dissolved

(μg/L) 

Co

diss

(μ

NONMINING SITES 

 Farncomb 0.1 5.6 3.8 39 <1 <1 6.5 <1 <1 <1 <1 <1 <

 Polk 0.1 5.9 5.6 44 <1 <1 107 <1 <1 <1 <1 <1 <

 Baker 0.3 7.3 9.6 71 <1 <1 5.6 <1 <1 <1 <1 <1 <

MINING SITES 

 Red 0.1 10 9,174 8,624 <1 <1 22.5 <1 2.2 2 1.2 16 33

 Canyon 0.2 3.9 10.9 77 <1 <1 29.3 <1 <1 <1 <1 <1 

 Ouray 0.2 5.1 17 1,660 <1 <1 29.2 <1 <1 <1 <1 2.8 1 Cutler 0.3 5.2 35.5 1,481 <1 <1 28.8 <1 <1 <1 <1 2.6  Ridgway 0.3 7.6 63.9 1,091 <1 1 32.9 <1 <1 <1 1.3 <1 

Site 

abbreviation 

Iron, 

total 

(μg/L) 

Lead, 

dissolved 

(μg/L) 

Lead, 

total 

(μg/L) 

Manganese, 

dissolved 

(μg/L) 

Manganese,

total 

(μg/L) 

Molybdenum, 

dissolved 

(μg/L) 

Nickel, 

dissolved

(μg/L) 

Silver, 

dissolved

(μg/L) 

Uranium, 

dissolved 

(μg/L) 

Zinc, 

dissolved 

(μg/L) 

Zinc, 

total 

(μg/L) 

Suspended 

sediments 

(mg/L) 

Dis

organ

(m

NONMINING SITES 

 Farncomb 42 <1 <1 1.9 <10 <1 <1 <1 <1 1.4 <10 0.9  Polk 54 <1 <1 1.6 <10 <1 <1 <1 <1 <1 <10 2.4  Baker 404 <1 <1 12 12 <1 <1 <1 <1 <1 <10 2 

MINING SITES 

 Red Mountain 9,990 20 22 696 638 <1 12 <1 <1 559 540 16  Canyon 123 <1 5.2 119 119 1.1 <1 <1 <1 113 124 3.4  Ouray 2,150 <1 13 213 215 <1 2.2 <1 <1 177 198 18  Cutler 1,795 <1 15 194 197 <1 2.2 <1 <1 102 176 14  Ridgway 1,435 <1 10 81 137 1.5 1.1 <1 <1 18 85 45 
50 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98 Appendix E. Streambed-sediment data for samples collected from nonmining and mining sites in the Upper Colorado Rive

1995–96 [--, no data; %, percent; μg/g, micrograms per gram-dry weight; data represent the less than 63-micrometer fraction] Site Site abbreviation Station number Date Time Aluminum (%) Antimony (μg/g) Arsenic (μg/g) Barium (μg/g) Beryllium (μg/g) Cadmium (μg/g) 

N

ONMININ

G

SITE

S

French Gulch above Farncomb Hill near Farncomb 392838105572900 09/04/96 0730 7.5 2.3 59 770 2.0 5.8 Polk Creek at Interstate Highway 70 near Vail, CO Polk 393527106143500 09/04/96 1400 8.3 1.0 4.8 840 3.2 <1 Colorado River below Baker Gulch near Granby, Baker 09010500 10/10/95 0830 7.5 0.7 7.1 620 4.0 <1 

MINING SITES

Red Mountain Creek above Crystal Lake near Red 375732107394000 10/18/95 0845 7.0 16 160 690 1.1 0.6 Canyon Creek below Squaw Gulch near Ouray, CO Canyon 380007107413600 10/17/95 0915 8.3 3.6 34 860 1.5 2.8 Uncompahgre River at Ouray, CO Ouray 380115107402001 10/18/95 1300 8.8 3.7 41 1,000 2.0 1.2 Uncompahgre River above Cutler Creek near Cutler 380448107420800 10/19/95 1010 8.4 4.4 29 1,100 1.7 2.6 Uncompahgre River near Ridgway, CO Ridgway 09146200 10/19/95 1400 7.4 3.7 32 780 1.6 3.0 

Site 

abbreviation 

Iron 

(%)

Lead 

(μg/g) 

Lithium 

(μg/g) 

Manganese 

(μg/g) 

Mercury 

(μg/g) 

Molybdenum 

(μg/g) 

Nickel 

(μg/g) 

Selenium 

(μg/g) 

Silver 

(μg/g) 

Strontium 

(μg/g) 

Thallium 

(μg/g) 

Titanium 

(μg/g) 

Uranium 

(μg/g) 

N

ONMININ

G

SITE

S

 Farncomb 3.9 150 36 1,300 0.05 6 30 2.0 1.1 260 <50 0.43 <50  Polk 3.6 43 47 670 0.05 12 29 1.0 1.3 130 <50 0.44 <50  Baker 4.6 23 40 1,100 0.04 <2 20 0.8 0.4 220 -- -- 14 

MINING SITES

 Red 15 850 16 470 0.54 10 3 1.7 22.4 260 <50 0.36 <500  Canyon 5.7 330 32 2,000 0.06 7 7 0.3 3.2 490 <50 0.53 <500  Ouray 7.3 190 41 1,100 0.04 6 10 0.3 2.2 380 <50 0.61 <500  Cutler 6.3 160 46 1,300 0.11 7 16 0.3 2.4 400 <50 0.57 <500  Ridgway 5.1 145 38 1,500 0.10 6 17 0.7 2.2 380 <50 0.44 <500 
APPENDIX 51

Appendix F. Transplanted bryophyte data for samples collected from nonmining and mining sites in the Upper Colorado RColorado, 1997–98 [Concentrations are mean values of three replicate samples; %, percent, μg/g, micrograms per gram-dry weight] 

Site name Site abbreviation Site identification Date Time Moisture (%) Aluminum (μg/g) Arsenic (μg/g) Barium (μg/g) Bery

(μ

NONMINING SITES 

French Gulch above Farncomb Hill near Farncomb 392838105572900 07/29/97 0800 82.0 6,690 4.0 194 0.Polk Creek at Interstate Highway 70 near Vail, CO Polk 393527106143500 08/12/98 1400 86.9 4,500 1.0 810 0.Colorado River below Baker Gulch near Granby, CO Baker 09010500 08/14/98 1200 86.0 2,645 1.5 255 0.

MINING SITES

Red Mountain Creek above Crystal Lake near Red 375732107394000 07/22/97 0900 82.7 3,960 14 56.5 0.Canyon Creek below Squaw Gulch near Ouray, CO Canyon 380007107413600 07/22/97 0800 82.6 6,763 15 322 1.Uncompahgre River at Ouray, CO Ouray 380115107402001 07/22/97 0730 84.9 9,390 7.1 197 1.Uncompahgre River above Cutler Creek near Ouray, Cutler 380448107420800 07/22/97 0700 82.4 8,760 7.8 208 1.Uncompahgre River near Ridgway, CO Ridgway 09146200 07/22/97 0630 82.1 6,567 6.1 211 0.

Nate Creek ditch near Owl Creek Pass, CO (1997)1 Nate (1997) 380929107334600 07/21/97 1700 85.5 3,600 1.0 449 0.

Nate Creek ditch near Owl Creek Pass, CO (1998)1 Nate (1998) 380929107334600 07/20/98 1300 87.4 3,803 1.1 442 0.

Site abbreviation Chromium (μg/g) Copper (μg/g) Iron (μg/g) Lead (μg/g) Magnesium (μg/g) Manganese (μg/g) Mercury (μg/g) Molybdenum (μg/g) Nickel (μg/g) Selenium (μg/g) St

NONMINING SITES

 Farncomb 6.7 34.3 14,533 14.7 3,613 1,663 0.06 0.47 10.3 1.37 

 Polk 4.3 36.4 6,653 4.0 3,556 6,533 0.06 1.0 5.2 3.73 

 Baker 3.5 35.7 6,395 2.5 2,915 5,755 0.06 0.95 6.3 2.45 

MINING SITES 

 Red Mountain 27 320 99,150 299 1,170 331 0.06 1.5 2.3 1.20 

 Canyon 11 286 14,577 202 3,223 3,783 0.09 1.3 12.3 1.21 1

 Ouray 5.8 1,970 42,500 95.8 1,810 3,360 0.06 2.7 15.0 1.40 1 Cutler 8.1 733 43,200 47.6 1,830 2,435 0.06 0.70 41.2 1.02 1 Ridgway 7.1 332 14,200 34.2 3,106 3,470 0.06 1.1 26 1.47 1 Nate (1997) 4.7 45.7 9,040 4.1 3,033 4,266 0.06 0.60 7.3 1.90 

 Nate (1998) 4.0 37.9 8,147 2.7 3,486 5,470 0.06 0.97 3.9 2.57 

 1 Bryophyte source material used for transplanting to the study sites. 
52 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Appendix G. Taxa, densities, total number of macroinvertebrates, and sampling date for samples 

collected from nonmining and mining sites in the Upper Colorado River Basin, Colorado, 

1997–98 

[Densities and total number of macroinvetebrates are rounded to three significant figures and reported as organisms per square meter; 

Site abbreviations are used in this Appendix; see table 1 for full site names; --, species not collected; *, Phylum; **, Suborder] 

 

NONMINING SITES MINING SITES 

Taxa Farncomb Polk Baker Red 

Mountain 

Canyon Ouray Cutler Ridgway 

 07/29/97 07/30/98 07/31/98 07/22/97 07/22/97 07/22/97 07/22/97 07/22/97 

CLASS 

ORDER 

 Family 

 Genus species 

ARTHROPODA (arthropods)* 

INSECTA (insects) 

EPHEMEROPTERA (mayflies) -- -- -- -- -- -- -- -- 

 Baetidae -- -- 243 -- -- -- -- -- 

 Baetis bicaudatus 655 -- -- -- 530 27.2 60.0 -- 

 Baetis flavistriga -- -- 46.4 -- -- -- -- -- 

 Baetis tricaudatus -- 492 154 -- -- -- -- 144 

 Baetis sp. -- 13.6 510 -- -- -- -- -- 

 Ephemerellidae -- -- -- -- -- -- -- -- 

 Drunella coloradensis 7.20 28.0 11.2 -- 17.6 1.60 2.40 -- 

 Drunella doddsi 47.2 32.8 130 -- -- -- -- -- 

 Drunella sp. -- -- 33.6 -- -- -- -- -- 

 Ephemerella infrequens -- -- -- -- -- -- -- 55.2 

 Ephemerella sp. -- -- 110 -- -- -- -- -- 

 Serratella tibialis -- -- 18.4 -- -- -- -- -- 

 Heptageniidae -- -- -- -- -- -- -- -- 

 Cinygmula sp. 372 130 96.0 -- -- -- 1.60 -- 

 Epeorus deceptivus 415 237 -- -- -- -- -- -- 

 Epeorus longimanus -- -- 114 -- -- -- -- -- 

 Eperous sp. 258 28.0 73.6 -- 3.20 -- 0.80 -- 

 Rhithrogena robusta 218 -- -- -- 22.4 -- -- -- 

 Rhithrogena sp. -- 167 45.6 -- -- -- -- 0.80 

 Leptophlebiidae -- -- -- -- -- -- -- -- 

 Paraleptophlebia sp. -- -- 17.6 -- -- -- -- -- 

PLECOPTERA (stoneflies) -- -- -- -- -- -- -- -- 

 Capniidae 6.40 -- 7.20 -- -- -- -- -- 

 Chloroperlidae 226 102 459 -- 8.00 -- 2.40 -- 

 Suwallia sp. -- 9.60 18.4 -- 84.8 8.80 40.8 -- 

 Sweltsa sp. 34.4 13.6 61.6 -- -- -- -- -- 

 Leuctridae -- -- -- -- -- -- -- -- 

 Paraleuctra sp. 3.20 18.4 -- -- -- -- -- -- 

 Nemouridae -- -- -- -- -- -- -- -- 

 Amphinemura banksi -- -- -- 0.80 -- -- -- -- 

 Zapada sp. 594 130 50.4 -- 50.4 9.60 7.20 -- 

 Perlidae -- -- -- -- -- -- -- -- 

 Claassenia sabulosa -- -- 0.80 -- -- -- -- -- 

 Hesperoperla pacifica -- -- 4.80 -- -- -- -- -- 

 Perlodidae -- -- 290 -- 2.40 -- 4.00 -- 

 Isoperla mormona -- -- -- -- -- -- -- 0.80 

 Isoperla quinquepunctata -- -- -- -- -- -- -- 2.40 

 Megarcys signata 31.2 60.0 86.4 -- 7.20 -- -- -- 

 Skwala americana -- -- 16.0 -- -- -- -- -- 

 Pteronarcyidae -- -- -- -- -- -- -- -- 

 Pteronarcella badia -- -- 36.0 -- 23.2 -- -- 24.0 

 Taeniopterygidae 0.80 -- -- -- -- -- -- -- 

TRICHOPTERA (caddisflies) -- -- -- -- -- -- -- -- 

 Brachycentridae -- -- -- -- -- -- -- -- 

 Brachycentrus americanus -- -- -- -- -- -- -- 36.0 

 Micrasema bactro -- -- 4.80 -- -- -- -- -- 

 Glossosomatidae -- -- -- -- -- -- -- -- 

 Glossosoma sp. -- -- 216 -- -- -- -- -- 

 Hydropsychidae -- -- -- -- -- -- -- -- 

 Arctopsyche grandis -- 4.80 55.2 -- 25.6 7.20 4.80 4.00 

 Hydropsyche sp. -- -- -- -- -- -- 1.60 18.4 

 Limnephilidae -- -- -- -- -- -- -- -- 

 Hesperophylax sp. -- -- -- -- -- -- -- 0.80 
APPENDIX 53

Appendix G. Taxa, densities, total number of macroinvertebrates, and sampling date 

for samples collected from nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1997–98–—Continued 

NONMINING SITES MINING SITES 

Taxa Farncomb Polk Baker Red 

Mountain 

Canyon Ouray Cutler Ridgway 

 07/29/97 07/30/98 07/31/98 07/22/97 07/22/97 07/22/97 07/22/97 07/22/97 

CLASS 

ORDER 

 Family 

 Genus species 

TRICHOPTERA, continued 

 Onocosmoecus unicolor -- -- -- -- -- -- -- 2.40 

 Rhyacophilidae -- -- -- -- -- -- -- -- 

 Rhyacophila alberta group -- -- -- -- -- 1.60 -- -- 

 Rhyacophila angelita -- -- 1.60 -- -- -- -- -- 

 Rhyacophila brunnea -- -- 40.0 -- -- -- -- -- 

 Rhyacophila coloradensis 0.80 69.6 -- -- -- -- -- -- 

 Rhyacophila hyalinata 16.8 51.2 -- -- 7.20 2.4 -- -- 

 Rhyacophila sp. 8.80 74.4 16.8 -- 1.60 -- -- -- 

 Uenoidae -- -- -- -- -- -- -- -- 

 Oligophlebodes minutus 7.20 -- -- -- -- -- 4.80 -- 

COLEOPTERA (beetles) -- -- -- -- -- -- -- -- 

 Dytiscidae -- -- -- -- -- -- -- -- 

 Oreodytes crassulus -- -- -- -- -- -- -- 0.80 

 Elmidae -- -- -- -- -- -- -- -- 

 Heterlimnius corpulentus -- 4.80 189 -- -- -- -- -- 

 Optioservus sp. -- -- 130 -- -- -- -- -- 

DIPTERA (true flies) -- -- -- -- -- -- -- -- 

 Blephariceridae -- -- -- -- -- -- -- -- 

 Bibiocephala grandis -- -- -- -- 0.80 -- -- -- 

 Ceratopogonidae 1.60 4.80 4.80 -- -- -- -- -- 

 Chironomidae 2.40 9.60 -- 2.40 3.20 3.20 3.20 0.80 

 Boreochlus sp. -- -- -- 0.80 -- -- -- -- 

 Brillia sp. 1.60 -- -- 1.60 2.40 2.40 8.80 -- 

 Cardiocladius sp. -- -- 8.80 -- -- -- -- -- 

 Corynoneura sp. 0.80 -- -- 0.80 -- -- -- 0.80 

 Cricotopus / Orthocladius sp. 0.80 -- 4.80 3.20 16.0 4.80 5.60 137 

 Diamesa sp. 4.80 -- -- 14.4 13.6 15.2 9.60 6.40 

 Eukiefferiella sp. 2.40 -- 2.40 3.20 -- -- -- 6.40 

 Metriocnemus fuscipes group 0.80 -- -- -- -- -- -- -- 

 Micropsectra sp. 1.60 -- -- 0.80 0.80 -- 1.60 0.80 

 Microtendipes sp. -- 9.60 -- -- -- -- -- -- 

 Pagastia sp. -- 4.80 1.60 0.80 -- -- -- -- 

 Paraphaenocladius sp. -- -- -- 31.2 2.40 0.80 4.80 -- 

 Parorthocladius sp. 0.80 -- -- -- -- -- -- -- 

 Polypedilum sp. -- -- -- -- -- -- 0.80 1.60 

 Pseudodiamesa sp. -- -- -- 1.60 -- 1.60 -- -- 

 Rheocricotopus sp. 2.40 13.6 -- -- 0.80 -- -- -- 

 Stempellinella sp. 2.40 32.8 -- -- -- -- -- -- 

 Thienemanniella sp. 0.80 -- -- -- -- -- -- -- 

 Thienemannimyia group -- -- -- -- -- -- -- 1.60 

 Tvetenia sp. 5.60 32.8 9.60 2.40 2.40 0.80 -- 2.40 

 Dixidae -- -- -- -- -- -- -- -- 

 Dixa sp. 0.80 -- -- -- -- -- 0.80 -- 

 Simuliidae -- -- -- -- -- -- -- -- 

 Prosimulium onychodactylum 77.6 32.8 3,200 0.80 1.60 1.60 0.80 -- 

 Simulium sp. -- 4.80 -- -- -- -- -- 2.40 

 Tipulidae -- -- -- -- -- -- -- -- 

 Dicranota sp. -- -- -- -- -- 1.60 -- -- 

 Hesperoconopa sp. -- -- -- -- -- 0.80 -- -- 

 Hexatoma sp. -- -- 4.00 -- -- -- -- 2.40 

 Limonia sp. -- -- -- -- 0.80 -- -- -- 

 Rhabdomastix sp. -- -- -- -- -- 0.80 -- -- 

 Tipula sp. 0.80 -- -- -- -- -- -- -- 

Brachycera** -- -- -- -- -- -- -- -- 

 Athericidae -- -- -- -- -- -- -- -- 

 Atherix pachypus -- -- -- -- -- -- -- 2.40 

 Empididae -- -- -- -- -- -- -- -- 

 Clinocera sp. -- -- -- 0.80 -- -- -- -- 
54 Relations of Benthic Macroinvertebrates to Concentrations of Trace Elements in Water, Streambed Sediments, and Transplanted 

Bryophytes and Stream Habitat Conditions in Nonmining and Mining Areas of the Upper Colorado River Basin, Colorado, 1995–98

Appendix G. Taxa, densities, total number of macroinvertebrates, and sampling date for 

samples collected from nonmining and mining sites in the Upper Colorado River Basin, 

Colorado, 1997–98—Continued 

NONMINING SITES MINING SITES 

Taxa Farncomb Polk Baker Red 

Mountain 

Canyon Ouray Cutler Ridgway 

 07/29/97 07/30/98 07/31/98 07/22/97 07/22/97 07/22/97 07/22/97 07/22/97 

CLASS 

ORDER 

 Family 

 Genus species 

CHELICERATA, continued 

ACARI (water mites) -- -- 33.6 -- -- -- -- -- 

 Lebertiidae -- -- -- -- -- -- -- -- 

 Lebertia sp. 0.80 -- -- -- -- -- -- 1.60 

MALACOSTRACA -- -- -- -- -- -- -- -- 

AMPHIPODA (scuds, shrimp) -- -- -- -- -- -- -- -- 

 Hyalellidae -- -- -- -- -- -- -- -- 

 Hyalella azteca -- -- -- -- -- -- 0.80 0.80 

ANNELIDA (worms)* -- -- -- -- -- -- -- -- 

OLIGOCHAETA (aquatic 

worms) 

-- 18.4 11.2 -- -- -- -- -- 

ENCHYTRAEIDA -- -- -- -- -- -- -- -- 

 Enchytraeidae 68.0 -- -- -- -- -- -- -- 

TUBIFICIDA -- -- -- -- -- -- -- -- 

 Naididae -- -- -- -- -- -- -- -- 

 Nais communis -- -- 2.40 -- -- -- -- -- 

NEMATODA (roundworms)* 17.6 -- 23.2 -- -- -- 16.8 -- 

PLATYHELMINTHES* -- -- -- -- -- -- -- -- 

TURBELLARIA (flatworms) -- -- -- -- -- -- -- -- 

TRICLADIDA -- -- -- -- -- -- -- -- 

 Planariidae -- -- -- -- -- -- -- -- 

 Polycelis coronata 26.4 13.6 -- -- -- -- -- -- 

TOTAL ABUNDANCE 3,120 1,840 6,590 68.0 828 92.0 185 457