U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2011–1159

Spring Runoff Water-Chemistry Data for the Standard Mine

and Elk Creek, Gunnison County, Colorado, 2010

Prepared in cooperation with the U.S. Environmental Protection Agency

Spring Runoff Water-Chemistry Data from 

the Standard Mine and Elk Creek, Gunnison 

County, Colorado, 2010

By Andrew H. Manning, Philip L. Verplanck, M. Alisa Mast, Joseph Marsik, and 

R. Blaine McCleskey

Prepared in cooperation with the U.S. Environmental Protection Agency

Open-File Report 2011–1159

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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Suggested citation:

Manning, A.H., Verplanck, P.L., Mast, M.A., Marsik, Joseph, and McCleskey, R.B., 2011, Spring runoff water-chemistry 

data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010: U.S. Geological Survey Open-File 

Report 2011–1159, 20 p.

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endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Contents

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

Introduction.....................................................................................................................................................1

Site Description.....................................................................................................................................4

Acknowledgments................................................................................................................................4

Methods...........................................................................................................................................................4

Sampling Sites.......................................................................................................................................4

Water-Chemistry Sampling .................................................................................................................5

Laboratory Methods.............................................................................................................................5

Data Quality............................................................................................................................................5

Results .............................................................................................................................................................7

Snowmelt Runoff Hydrology ...............................................................................................................7

Water Chemistry .................................................................................................................................12

Major Ions and Trace Elements...............................................................................................12

Oxygen-18 and Deuterium........................................................................................................17

Conclusions...................................................................................................................................................19

References Cited..........................................................................................................................................19

Figures

1. Location of Standard Mine and Elk Creek ................................................................................2

2. Location of sample sites..............................................................................................................3

3. Comparison of analytical results by using ICP–MS (inductively coupled 

plasma–mass spectrometry) and ICP–AES (inductively coupled plasma–atomic 

emission spectroscopy)...............................................................................................................8

4. Snow water equivalent data from Schofield Pass snow telemetry site (A) and 

streamflow data from the East River near the town of Crested Butte (B) for the 

years 2007 and 2010 compared to mean values ......................................................................9

5. Streamflow records for the Level 1 portal, ELK-00 gage, and the USGS East River 

gage for the spring of 2010. Snow water equivalent (SWE) measured at the 

Schofield Pass snow telemetry site is also shown.................................................................9

6. Photographs showing snowpack at the Level 1 portal on the six sampling days 

(A through F) during the spring of 2010 ...................................................................................10

7. Photographs showing flow in Elk Creek on the six sampling days (A through F) 

during the spring of 2010 ...........................................................................................................11

8. Box-and-whisker plots comparing 2007 and 2010 measurements at sample site 

EC-MSTD1 (A) and sample site EC-CELK1 (B)........................................................................13

9. pH (A) and specific conductance (B) plotted versus sample date.....................................14

10. Calcium (A) and sulfate (B) concentration plotted versus sample date............................14

11. Zinc (A), cadmium (B), manganese (C), lead (D), and copper (E) concentration 

plotted versus sample date. Only samples with concentrations above detection 

limit are shown............................................................................................................................15

12. Bar charts showing calculated loads for zinc (A), cadmium (B), manganese (C), 

lead (D), and copper (E).............................................................................................................16

13. d18O (A) and d2H (B) values plotted versus calendar day of sample collection................18
iv

Tables

1. Sample site information...............................................................................................................4

2. Methods of analysis and detection limits.................................................................................6

3. Concentrations of major ions and selected metals ........................................................... link

4. Results of inductively coupled plasma-mass spectrometry (ICP-MS) analyses .......... link

5. Oxygen-18 and deuterium results ............................................................................................17

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (cfs) 0.02832 cubic meter per second (m3

/s)

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

°F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

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

25 °C).

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

or micrograms per liter (μg/L).
Abstract

Water samples were collected approximately every two 

weeks during the spring of 2010 from the Level 1 portal of 

the Standard Mine and from two locations on Elk Creek. The 

objective of the sampling was to: (1) better define the expected 

range and timing of variations in pH and metal concentrations 

in Level 1 discharge and Elk Creek during spring runoff; and 

(2) further evaluate possible mechanisms controlling water 

quality during spring runoff. Samples were analyzed for major 

ions, selected trace elements, and stable isotopes of oxygen 

and hydrogen (oxygen-18 and deuterium). The Level 1 portal 

sample and one of the Elk Creek samples (EC-CELK1) were 

collected from the same locations as samples taken in the 

spring of 2007, allowing comparison between the two different years. Available meteorological and hydrologic data suggest that 2010 was an average water year and 2007 was below 

average.

Field pH and dissolved metal concentrations in Level 1 

discharge had the following ranges: pH, 2.90 to 6.23; zinc, 

11.2 to 26.5 mg/L; cadmium, 0.084 to 0.158 mg/L; manganese, 3.23 to 10.2 mg/L; lead, 0.0794 to 1.71 mg/L; and 

copper, 0.0674 to 1.14 mg/L. These ranges were generally 

similar to those observed in 2007. Metal concentrations near 

the mouth of Elk Creek (EC-CELK1) were substantially lower 

than in 2007. Possible explanations include remedial efforts 

at the Standard Mine site implemented after 2007 and greater 

dilution due to higher Elk Creek flows in 2010. Temporal patterns in pH and metal concentrations in Level 1 discharge were 

similar to those observed in 2007, with pH, zinc, cadmium, 

and manganese concentrations generally decreasing, and lead 

and copper generally increasing during the snowmelt runoff 

period. Zinc and cadmium concentrations were inversely 

correlated with flow and thus apparently dilution-controlled. 

Lead and copper concentrations were inversely correlated with 

pH and thus apparently pH-controlled. Zinc, cadmium, and 

manganese concentrations near the mouth of Elk Creek did not 

display the pronounced increase observed during high flow in 

2007, again perhaps due to remedial activities at the mine site 

or greater dilution in 2010.

Zinc and cadmium loads near the mouth of Elk Creek 

were generally greater than those at the Level 1 portal for the 

six sample days in 2010. Whereas metal loads in September 

2007 suggested that Level 1 portal discharge was the primary 

source of metals to the creek, metal loads computed for this 

study suggest that this may not have been the case in the 

spring of 2010. d18O values are well correlated with flow, 

becoming lighter (more negative) during snowmelt in both 

Level 1 discharge and Elk Creek. Seasonal variations in the 

chemistry of Level 1 discharge, along with portal flow tracking very closely with creek flow, are consistent with geochemical and environmental tracer data from 2007 that indicate 

short residence times (<1 year) for groundwater discharging 

from the Standard Mine.

Introduction

In 2006, the U.S. Environmental Protection Agency 

(USEPA) listed the Standard Mine in the Elk Creek watershed 

near Crested Butte, Colorado (fig. 1), as a Superfund Site. 

Drainage from the Standard Mine enters Elk Creek, contributing dissolved and suspended loads of zinc, cadmium, copper, 

and other metals to the stream. Elk Creek flows into Coal 

Creek, which is a source of drinking water for the town of 

Crested Butte. This study is the latest in a series of studies 

performed by the U.S. Geological Survey (USGS) since 2006 

to characterize the geology, hydrogeology, and water chemistry in the vicinity of the Standard Mine and assist the USEPA 

in evaluating remedial options for the site (Verplanck and others, 2007; Manning and others, 2008; Caine and others, 2010; 

Minsley and others, 2010; Verplanck and others, 2010).

The purpose of this report is to provide additional data to: 

(1) better define the expected range and timing of variations in 

pH and metal concentrations in Level 1 portal discharge and 

Elk Creek during spring runoff; and (2) further evaluate possible mechanisms controlling water quality during spring runoff. Water-chemistry samples were collected from the Level 1 

portal of the Standard Mine (EC-MSTD1) and two locations 

on Elk Creek during the spring of 2010 (fig. 2). The two Elk 

Creek locations include EC-CELK1 located just above the 

confluence with Coal Creek, and EC-CELK2 located approximately one-third of the distance downstream from EC-MSTD1 

to EC-CELK1 (close to USEPA sample site ELK-08). Samples were collected approximately every two weeks during 

the snowmelt runoff period in April, May, and June, 2010. 

Spring Runoff Water-Chemistry Data from the Standard 

Mine and Elk Creek, Gunnison County, Colorado, 2010

By Andrew H. Manning, Philip L. Verplanck, M. Alisa Mast, Joseph Marsik, and R. Blaine McCleskey
2 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Mt. Emmons

Standard

Mine

Daisy

Mine

Keystone

Mine

Peeler Lakes

Copley

Lake

Crested Butte

Scarp Ridge

Elk Cr.

Coal Cr.

Oh-Be-Joyful Cr.

Redwell Cr.

Slate

River

Nicholson

Lake

38o52'30"

38o55'00"

107o 107 00' o

05'

mile

kilometer

0 0.5 1

0 0.5 1

Colorado

Colorado

Plateau

Southern

Rocky

Mountains

Great Plains

Denver

Crested Butte

Figure 1

Figure 1. Location of Standard Mine and Elk Creek.
Introduction 3

EC-CELK1

EC-CELK2

EC-MSTD1

107o05' 107o04' 107o03'

38o52'

38o53'

mile

kilometer

0 0.5 1

0 0.5 1

Figure 2

Figure 2. Location of sample sites. Base map compiled from U.S. Geological Survey 1:24,000 topographic maps of the 

Oh-Be-Joyful, Colo. and Mt Axtell, Colo. quadrangles (1973). Contour interval, 40 feet.
4 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Samples were analyzed for pH and specific conductance, as 

well as concentrations of major ions, selected trace elements, 

and stable isotopes of oxygen and hydrogen (oxygen-18 and 

deuterium). Five samples were collected by the USGS from 

EC-MSTD1 and EC-CELK1 during the same period in 2007 

and analyzed for the same water quality constituents (Manning 

and others, 2008).

Site Description

The Standard Mine is located within the Elk Creek watershed, a roughly 2-square mile subalpine to alpine watershed 

located approximately 4 miles (mi) west-northwest of Crested 

Butte in west-central Colorado (fig. 1). Land-surface elevations in the watershed range from 9,600 to 12,200 feet (ft) (fig. 

2). Vegetation is subalpine to alpine, consisting of dominantly 

mixed spruce and fir forest or tundra. The closest meteorological stations are in the town of Crested Butte at an elevation of 

8,860 ft (http://www.wrcc.dri.edu), at Crested Butte Ski Area 

about 6 mi to the northeast at an elevation of 10,160 ft, and 

at Schofield Pass about 10 mi to the north at an elevation of 

10,700 ft (http://www.wcc.nrcs.usda.gov/snotel). Data from 

these stations indicate that likely ranges (elevation-dependent) 

for mean annual air temperature, mean annual precipitation, 

and percentage of precipitation falling as snow for the Elk 

Creek watershed are 0° to 2°C, 25 to 50 inches (in), and 55 to 

75 percent, respectively. Snow cover generally persists from 

November through May. Streamflow records for Elk Creek 

are available from 2008 onward (Jan Christner, URS Corporation, oral communication, February 2011), measured at the 

USEPA’s ELK-00 site located at the mouth of Elk Creek just 

below sample site EC-CELK1 (fig. 2). Available data indicate 

baseflows on the order of 0.1 cubic feet per second (cfs), and 

spring high flows on the order of 10 cfs. The stream is perennial and snowmelt-dominated, with the majority of annual 

discharge occurring in April, May, and June.

The Standard Mine is an abandoned, underground, hardrock mine within the Ruby mining district that was mined 

intermittently from 1880 through the 1960s (Wood and Oerter, 

2007). Metals mined at the deposit included silver, lead, zinc, 

and copper. The primary mineral deposit targeted was a polymetallic vein system associated with the Standard fault that 

contained sphalerite, pyrite, argentiferous galena, and chalcopyrite. Sharp (1978) concluded that the poly-metallic vein 

mineralization in the upper Elk Creek watershed (including the 

Standard fault vein) appear genetically and spatially related to 

an underlying Tertiary rhyolite porphyry stock, exposed to the 

northeast in Redwell basin. The mine consists of four adits and 

several stopes and shafts that generally follow the Standard 

fault vein (Colorado Division of Reclamation, Mining, and 

Safety, 2007). The adits are designated Levels 1, 2, 3, and 5, 

in sequence from lowermost to uppermost. The Level 1 and 

Level 5 portals are the only portals that consistently drain 

water. Level 1 discharges considerably more water than the 

other levels and thus is the largest potential source of metals in 

Elk Creek associated with the Standard Mine.

Acknowledgments

This work was done in cooperation with the USEPA. 

We greatly appreciate the efforts of Mackenzie Johnston, 

Jim Coogan, and Tom Sunderland for assisting in the sample 

collection. We thank Robert Runkel and Thomas Chapin of 

the USGS for reviewing this report and providing helpful 

comments.

Methods

Sampling Sites

Table 1 and Figure 2 provide sample site locations. One 

sample was collected from Level 1 portal discharge (ECMSTD1) and two samples were collected from Elk Creek 

(EC-CELK1 and EC-CELK2) at six different times during 

the Spring of 2010: March, 28th; April 22nd; May 6th and 23rd; 

and June 9th and 21st. Sites EC-MSTD1 and EC-CELK1 were 

sampled previously by the USGS in 2006, 2007, and 2009 

(Manning and others, 2008; Verplanck and others, 2010).

Table 1. Sample site information.

[ft, feet; m, meter; coordinates are Universal Transverse Mercator (UTM) coordinate system, North American 

Datum of 1983, Zone 13]

Site Name Easting

(m)

Northing

(m) Description Elevation(ft)

EC-CELK1 321270 4302915 Elk Creek near confluence with Coal Creek 9,579

EC-CELK2 319815 4304521 Elk Creek near USEPA site ELK-08 10,558

EC-MSTD1 320124 4305517 Standard Mine, Level 1 Portal 11,008
Methods 5

Water-Chemistry Sampling

Measurements of pH, specific conductance (SC), and 

temperature were taken in the field and again in the laboratory 

within five days of sample collection. Samples for major-ion 

and trace-element analyses were filtered onsite through a 

0.45-micrometer (μm) capsule filter. Four of the six samples 

collected from EC-CELK1 (those collected May 6th through 

June 21st) were also filtered through a 0.1-μm syringe filter. 

Several sample aliquots were collected, including: an unfiltered, nitric acid acidified aliquot (raw acidified, or RA) for 

total-recoverable major cation and trace-element determinations; a 0.45- μm filtered, nitric acid acidified aliquot (filtered 

acidified, or FA) for dissolved major cation and trace-element 

determinations; a 0.45-μm filtered, unacidified aliquot (filtered 

unacidified, or FU) for anion and alkalinity determinations; 

and a 0.45-μm filtered, hydrochloric acid acidified aliquot 

(also FA) for iron redox species determinations. Additionally, 

a 0.1-μm filtered, nitric acid acidified aliquot (FA 0.1) for 

dissolved major cation and trace-element determinations was 

collected for four of the samples from EC-CELK1. Bottles 

for FA, FA 0.1, and RA aliquots were presoaked in nitric acid, 

rinsed in distilled water, and prerinsed with sample water. 

Bottles for FU aliquots were presoaked in distilled water and 

prerinsed with sample water. Opaque bottles for iron redox aliquots were presoaked in hydrochloric acid, rinsed in distilled 

water, and prerinsed with sample water. Appropriate aliquots 

were acidified with ultrapure acid and then stored on ice until 

refrigerated. Samples for analysis of oxygen and hydrogen 

isotopic compositions (d18O, d2

H) of water were collected in 

borosilicate glass bottles (unfiltered, unpreserved).

Laboratory Methods

All reagents were of a purity at least equal to the reagentgrade standards of the American Chemical Society. Doubledistilled deionized water, and redistilled acids using a subboiling purification technique (Kuehner and others, 1972), were 

used in all preparations. The analytical method and detection 

limit for each analyte are listed in table 2. USGS standard 

reference water samples and blanks were included with each 

sample suite for inductively coupled plasma atomic-emission 

spectroscopy (ICP-AES) and inductively coupled plasma-mass 

spectrometry (ICP-MS). Major cations (calcium, magnesium, 

potassium, and sodium) and silica and selected trace elements 

(aluminum, boron, barium, cadmium, copper, iron, manganese, 

lead, strontium, and zinc) for total-recoverable and dissolved 

samples were determined using a Leeman Labs DRE-DTM 

ICP-AES. Trace elements for total-recoverable and dissolved 

samples were analyzed with the Elan DCRe ICP-MS using a 

method developed by the U.S. Geological Survey (Meier and 

others, 1994; Lamothe and others, 2002). This method is used 

to directly determine the elements in the water samples without 

need for any preconcentration or dilution. Elemental detection 

limits are in the subparts per billion range (table 2), and the 

working linear range is six or more orders of magnitude.

Concentrations of major anions (Cl-

, F-, NO3

-

 and SO4

-

) 

were determined by ion chromatography (Brinton and others, 1995) using a Dionex 600TM ion chromatograph with a 

25-microliter injection loop. USGS standard-reference-water 

samples were used as independent quality-control standards. 

Alkalinity (as HCO3

-

) was determined using an Orion 960TM 

autotitrator and standardized H2SO4 (Barringer and Johnsson, 

1989). Samples were diluted as necessary to bring the analyte 

concentration within the optimal range of the method. Iron (II) 

and total iron were determined using a modification of the FerroZineTM colorimetric method (Stookey, 1970; To and others, 

1999) with a Hewlett Packard 8453TM diode array ultraviolet/

visible (UV/VIS) spectrophotometer.

Samples for analysis of oxygen (d18O) and hydrogen 

(d2H) isotopic compositions of water were analyzed by the 

U.S. Geological Survey Stable Isotope Laboratory in Denver, 

Colorado. Oxygen isotopic compositions were determined 

using a Micromass Optima with an automated CO2 equilibration technique adapted from Epstein and Mayeda (1953). 

Water samples were prepared for hydrogen-isotopic analyses 

using the zinc-reduction technique (Kendall and Coplen, 

1985). The hydrogen analyses were performed on a Finnigan 

MAT 252 mass spectrometer. Values of d18O and d2H were 

relative to Vienna Standard Mean Ocean Water (VSMOW), 

and they have reproducibility of approximately 0.2 and 1.0 

permil, respectively.

Data Quality

Field and laboratory measurements of SC were in 

close agreement (generally within 5%). Field and laboratory 

measurements of pH showed similar temporal variations, but 

often differed somewhat; field pH was commonly 10 to 20 

percent lower than lab pH. Testing of the two different meters 

used to measure field and laboratory pH immediately after the 

sampling period revealed that, although the field pH meter 

performed well in calibration standards, it equilibrated slowly 

and read as much as 0.2 pH units low in acidic natural waters 

and 1.0 pH unit low in circum-neutral natural waters compared to other pH probes tested in the laboratory. The laboratory pH measurements may have differed slightly from the pH 

of sampled water in the field given that it was measured days 

after sample collection. It is thus difficult to determine whether 

field or laboratory pH is more reliable. Both measurements 

are provided in this report (table 3). However, all figures and 

discussion involving pH henceforth refer to field pH measurements because only the field pH data are available for all six 

sampling events.

Quality control included replicate samples, field-equipment blanks, analyses by alternative methods, analysis of 

standard reference water samples, and calculation of charge 

imbalance. Replicate samples are two field-collected samples 

that are considered to be essentially identical in composition 

and are used to estimate variability in environmental data. 

Replicate samples were collected immediately following the 

environmental sample. Each replicate sample was processed 
6 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Table 2. Methods of analysis and detection limits.

[mg/L, milligram per liter; μg/L, microgram per liter; IC, ion chromatography; ICP-MS, inductively coupled plasma-mass 

spectrometry; ICP-AES, inductively coupled plasma-atomic emission spectroscopy]

Element Detection limit Method Element Detection limit Method

Ag 1 μg/L ICP-MS Mn 1 μg/L ICP-AES

Al 80 μg/L ICP-AES Mn 0.2 μg/L ICP-MS

Al 2 μg/L ICP-MS Mo 2 μg/L ICP-MS

As 1 μg/L ICP-MS Na 1 mg/L ICP-AES

B 10 μg/L ICP-AES Nb 0.2 μg/L ICP-MS

Ba 0.8 μg/L ICP-AES Nd 0.01 μg/L ICP-MS

Ba 0.2 μg/L ICP-MS Ni 0.4 μg/L ICP-MS

Be 0.05 μg/L ICP-MS NO3

- 0.05 mg/L IC

Bi 0.2 μg/L ICP-MS P 10 μg/L ICP-MS

Ca 0.02 mg/L ICP-AES Pb 7 μg/L ICP-AES

Cd 1 μg/L ICP-AES Pb 0.05 μg/L ICP-MS

Cd 0.02 μg/L ICP-MS Pr 0.01 μg/L ICP-MS

Ce 0.01 μg/L ICP-MS Rb 0.01 μg/L ICP-MS

Cl- 0.1 mg/l IC Sb 0.3 μg/L ICP-MS

Co 0.02 μg/L ICP-MS Sc 0.6 μg/L ICP-MS

Cr 1 μg/L ICP-MS Se 1 μg/L ICP-MS

Cs 0.02 μg/L ICP-MS SiO2 0.06 mg/L ICP-AES

Cu 3 μg/L ICP-AES SO4

- 0.1 mg/L IC

Cu 0.5 μg/L ICP-MS Sm 0.01 μg/L ICP-MS

Dy 0.005 μg/L ICP-MS Sr 0.7 μg/L ICP-AES

Er 0.005 μg/L ICP-MS Sr 0.5 μg/L ICP-MS

Eu 0.005 μg/L ICP-MS Ta 0.02 μg/L ICP-MS

F- 0.05 mg/l IC Tb 0.005 μg/L ICP-MS

Fe 3 μg/L ICP-AES Th 0.2 μg/L ICP-MS

Fe 2 μg/L FerroZine Ti 0.5 μg/L ICP-MS

Fe (II) 2 μg/L FerroZine Tl 0.1 μg/L ICP-MS

Ga 0.05 μg/L ICP-MS Tm 0.005 μg/L ICP-MS

Gd 0.005 μg/L ICP-MS U 0.1 μg/L ICP-MS

Ho 0.005 μg/L ICP-MS V 0.5 μg/L ICP-MS

K 0.03 mg/L ICP-AES W 0.5 μg/L ICP-MS

K 0.03 μg /L ICP-MS Y 0.01 μg/L ICP-MS

La 0.01 μg/L ICP-MS Yb 0.01 μg/L ICP-MS

Li 0.1μg/L ICP-MS Zn 2 μg/L ICP-AES

Mg 0.002 mg/L ICP-AES Zn 3 μg/L ICP-MS
Results 7

through all the steps of the environmental sample using a new 

filter and clean equipment. Replicate samples were analyzed at 

the same time using the same instruments as the other samples 

collected during the same sampling trip. Analytical results of 

replicate samples are included in tables 3 and 4, and follow the 

associated environmental sample (sample name ending with 

R). Most major, minor, and trace-element replicate concentrations are within ±10 percent of the corresponding environmental sample.

A field-equipment blank is a sample prepared using 

deionized water passed through all the sampling and processing equipment. This type of sample is used to check for the 

potential contamination of the water-chemistry samples during 

collection, processing, handling, and analysis. Analytical 

results are included in tables 3 and 4, designated EB-08 and 

EB-09 (equipment blank). All analytes were below analytical detection limits except for bicarbonate alkalinity, which 

was consistently measured at 2 mg/L, just above the reporting 

limit.

Concentrations of cations were determined by ICP-AES 

and ICP-MS. Good agreement between ICP-AES and ICP-MS 

results was observed for constituents with concentrations at 

least three times the detection limit (fig. 3). Barium, calcium, 

manganese, strontium, and zinc were chosen for comparison in 

Figure 3 because the range in concentrations of these elements 

was within the working range of both analytical techniques.

Data for all samples with complete analyses were 

checked using the computer program WATEQ4F (Ball and 

Nordstrom, 1991) for charge imbalance (C.I.), using the following calculation:

 anions)/2 sum cations (sum

- cations (sum * 100 anions) sum

 (percent) C.I.

+

=

where sum cations is the sum of the cations in milliequivalents 

per liter, and sum anions is the sum of the anions in milliequivalents per liter. The percent-charge imbalance reflects 

how well the major anions and cations balance and usually 

is an independent measure of the accuracy of the analytical 

techniques. The percent-charge imbalance was low (less than 

10 percent) for all samples (table 3) except four of the most 

dilute samples for which the imbalance was approximately 

15 percent. This is not uncommon for dilute samples because 

analytical uncertainty increases at concentrations approaching 

instrument detection limits, and unmeasured organic anions 

can be important in dilute samples. 

Results

Snowmelt Runoff Hydrology

Snowpack measurements are not available for the Elk 

Creek watershed. However, two snowpack telemetry (SNOTEL) sites are relatively close: Butte is located about 6 mi to 

the northeast, and Schofield Pass is about 10 mi to the north 

(http://www.wcc.nrcs.usda.gov/snotel). Schofield Pass was 

chosen as the most representative site because its elevation 

of 10,700 ft is closer to the mean elevation of the Elk Creek 

watershed (about 10,900 ft). Figure 4A shows snow water 

equivalent (SWE) data for Schofield Pass for the period of 

March 1st to July 1st for the years 2010 and 2007. Mean SWE 

for years 1986 to 2010 is also shown for reference. The year 

2007 is shown in addition to 2010 because water-chemistry 

data for these two years are discussed and compared below. 

2010 maximum SWE at Schofield Pass was near average, and 

2007 maximum SWE was 20 percent below average.

Elk Creek streamflows have been measured since 2008, 

but this is too short a period to provide meaningful average 

flows against which 2010 and 2007 flows can be compared. 

The nearest available stream gage with a long-term record is 

a USGS station on the East River located about 12 mi to the 

southeast just downstream from the confluence with Cement 

Creek (http://waterdata.usgs.gov/co/nwis/rt). Figure 4B shows 

East River streamflow data for the period of March 1st to July 

1st for the years 2010 and 2007. Mean, 25th percentile, and 75th

percentile flows for years 1964 to 2010 also are shown for reference. Discharge during spring runoff in 2010 was generally 

average to above average. 2007 flows are near average early 

in the runoff period, but during late May and early June (when 

annual maximum flows typically occur) flows are generally 

less than the 25th percentile, indicating below-average total 

spring runoff.

The SWE data from Schofield Pass suggest that the 

amount of water stored in the snowpack in the Elk Creek 

watershed was near average prior to snowmelt in 2010, and 

below average in 2007. Similarly, streamflow data from the 

East River suggest that spring runoff flows in Elk Creek were 

near average in 2010 and below average in 2007. In short, 

available meteorological and hydrologic information suggest that the water-quality data collected in spring 2010 are 

representative of an average water year, and those collected in 

spring 2007 are representative of a low-water year. 

Figure 5 shows 2010 streamflow data for the ELK-00 

gage on Elk Creek, located immediately downstream of 

sampling site EC-CELK1 (fig. 2), and the gage at the Level 

1 portal, co-located with sampling site EC-MSTD1. 2010 

flows for the East River and 2010 SWE for Schofield Pass are 

also shown. Photographs in Figures 6 and 7 display changes 

in snowpack at the Level 1 portal and changes in flow in Elk 

Creek through the spring of 2010. Flow at all three stream 

gage sites followed a similar pattern during the 2010 snowmelt 

runoff period. Peak flows occurred within the period of June 

7th to 9th, with flows at the Level 1 portal, ELK-00, and East 

River reaching 0.30, 24, and 2,700 cfs, respectively. These 

peak flows were 1.5 to 2 orders of magnitude greater than 

baseflows in early March. Flows are closely correlated with 

Schofield Pass SWE; constant or decreasing flows correspond 

to periods of constant or increasing SWE, and increasing 

flows correspond to periods of decreasing SWE (snowmelt). A 

unique feature of the flow record at all three sites is a drop in 

late April that leads to a double peak. This drop is synchronous 
8 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010 ICP-AES, IN MILLIGRAMS PER LITER

ICP-MS, IN MILLIGRAMS PER LITER

B

0 20 40 60 80 100

0

20

40

60

80

100

Calcium

ICP-AES, IN MILLIGRAMS PER LITER

ICP-MS, IN MILLIGRAMS PER LITER

C

0 2 4 6 8 10 12

0

2

4

6

8

10

12

Manganese

0.000 0.005 0.010 0.015 0.020 0.025

0.000

0.005

0.010

0.015

0.020

0.025

Barium

ICP-AES, IN MILLIGRAMS PER LITER

ICP-MS, IN MILLIGRAMS PER LITER

A

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Strontium

ICP-AES, IN MILLIGRAMS PER LITER

ICP-MS, IN MILLIGRAMS PER LITER

D

0 5 10 15 20 25 30

0

5

10

15

20

25

30

Zinc

ICP-AES, IN MILLIGRAMS PER LITER

ICP-MS, IN MILLIGRAMS PER LITER

E

Figure 3 Figure 3. Comparison of analytical results by using ICP–MS (inductively coupled plasma–mass 

spectrometry) and ICP–AES (inductively coupled plasma–atomic emission spectroscopy). Barium 

(A), calcium (B), manganese (C), strontium (D), and zinc (E) concentration. Solid diagonal line, 1:1 

correspondence; dashed line, 10 percent variation.
Results 9

Figure 4. Snow water equivalent data from Schofield Pass snow telemetry site (A) and streamflow 

data from the East River near the town of Crested Butte (B) for the years 2007 and 2010 compared to 

mean values. Mean snow water equivalent is for years 1986 to 2010. Mean, 25th percentile, and 75th

percentile streamflow values are for years 1964 to 2010.

Figure 4

0

5

10

15

20

25

30

35

40

45

3/1 4/1 5/1 6/1 7/1

SNOW WATER EQUIVALENT, IN INCHES

CALENDAR DAY

A

2010

2007

Mean

0

500

1000

1500

2000

2500

3000

3/1 4/1 5/1 6/1 7/1

2010

2007

Mean

25th and 75th

Percentile

FLOW, IN CUBIC FEET PER SECOND

CALENDAR DAY

B

3/1 4/1 5/1 6/1 7/1

0

5

10

15

20

25

30

35

40

45

Level 1 Portal ELK-00 East River Schofield Pass SWE

104

103

102

101

100

10-1

10-2

10-3

DATE

FLOW, IN CUBIC FEET PER SECOND

SNOW WATER EQUIVALENT, IN INCHES

Figure 5. Streamflow records for the Level 1 portal, ELK-00 

gage, and the USGS East River gage for the spring of 2010. 

Snow water equivalent (SWE) measured at the Schofield 

Pass snow telemetry site is also shown.
10 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

Figure 6. Photographs showing snowpack at the Level 1 portal on the six sampling days (A through F) during the spring of 2010. Snow 

water equivalent (SWE) values are from the Schofield Pass snow telemetry site.

Figure 6

(A) March 28, Schofield Pass SWE 33.6 inches. (B) April 22, Schofield Pass SWE 28.5 inches.

(C) May 6, Schofield Pass SWE 32.5 inches. (D) May 23, Schofield Pass SWE 24.9 inches.

(E) June 9, Schofield Pass SWE 0.0 inches. (F) June 21, Schofield Pass SWE 0.0 inches.
Results 11

Figure 7

(A) March 28, ELK-00 flow 0.30 cfs. (B) April 22, ELK-00 flow 14 cfs.

(C) May 6, ELK-00 flow 3.3 cfs. (D) May 23, ELK-00 flow 14 cfs.

(E) June 9, ELK-00 flow 23 cfs. (F) June 21, ELK-00 flow 6.4 cfs.

Figure 7. Photographs showing flow in Elk Creek on the six sampling days (A through F) during the spring of 2010. Flow values (in cubic 

feet per second, or cfs) are from the ELK-00 gage located immediately downstream from sampling site EC-CELK1 where all photos were 

taken. All views are looking upstream from the sampling site, except photo A (March 28th) which shows the sampling hole dug through 

snow that completely covered the stream. 
12 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

with a distinct rebound in SWE that causes a similar double 

peak in the SWE curve. A close correlation between SWE and 

flow is expected for the two surface water sites, but is less 

intuitive for the Level 1 portal given that snowmelt water must 

flow as groundwater through a substantial mass of rock (tunnel overburden thickness of up to 1000 ft) prior to reaching 

Level 1. The rapid response of Level 1 portal flow to the onset 

of snowmelt (<3 days) is consistent with geochemical and 

environmental tracer data collected previously from the Level 

1 portal (Manning and others, 2008) which indicate short 

residence times (<1 year) for groundwater discharging from 

the Standard Mine.

Water Chemistry

Major Ions and Trace Elements

The following discussion focuses on the field parameters 

pH and SC; the major ions calcium (Ca) and sulfate (SO4); 

and the metals zinc (Zn), cadmium (Cd), manganese (Mn), 

lead (Pb), and copper (Cu) to remain consistent with previous reports (Manning and others, 2008; Verplanck and others, 

2010). All concentrations discussed are dissolved concentrations unless otherwise noted. Field parameter values, 

major-ion concentrations, and metal concentrations measured 

in 2007 (Manning and others, 2008) and in 2010 at sites ECMSTD1 and EC-CELK1 are compared on box-and-whisker 

plots in Figure 8. For EC-MSTD1, 2007 and 2010 values 

are similar, though the range of values measured in 2010 is 

larger than in 2007 for most constituents. The lower minimum concentrations in 2010 may be due to greater dilution 

resulting from higher flows at the Level 1 portal in 2010 (fig. 

4). It is also possible that variations in the chemistry of Level 

1 portal discharge in 2007 actually were as large as in 2010, 

but the full range simply was not captured by the samples 

collected. For EC-CELK1, 2007 and 2010 values are similar 

for the field parameters and major ions. As at EC-MSTD1, 

2010 values cover a larger range than 2007 (pH excepted), 

and possible reasons for this are the same as explained above. 

However, metal concentrations are notably lower in 2010 than 

in 2007. Maximum concentrations of Zn, Cd, and Mn are 60 

to 90 percent lower, and maximum concentrations of Pb and 

Cu are about 50 percent lower. The lower concentrations may 

be due to remedial efforts at the Standard Mine site implemented after 2007, including the installation of a bioreactor 

for treating Level 1 portal discharge (just downstream of ECMSTD1) and the relocation of waste rock and tailings (URS 

Operating Services, 2010). The lower values also may be due 

to greater dilution resulting from higher flows in Elk Creek in 

2010 (fig. 4).

Figures 9, 10, and 11 show temporal trends in field pH 

and SC, major-ion concentrations, and selected metal concentrations at all three sample sites through the spring of 

2010. Flow records for the Level 1 portal and ELK-00 also 

are shown for reference. Field pH and SC values display a 

first-order trend of decreasing during spring high flows, as 

observed in 2007 (fig. 9). At the Level 1 portal, the largest 

pH drop (from about 6 to about 3) occurs early in the spring 

runoff period, apparently due to the mobilization of a low-pH 

water source in the early stages of snowmelt. Specific conductance is apparently dilution-controlled, with lower values 

well correlated with higher flows and vice versa. Both of these 

patterns were observed in the 2007 data as well. Like SC, 

major-ion concentrations are in general inversely proportional 

to flow and appear to be dilution-controlled (fig. 10). The same 

was observed in 2007. A distinct late-April rebound in majorion concentrations, which otherwise decrease from March to 

early June, clearly corresponds to a late-April cold spell and 

associated decrease in streamflow evident in both flow records 

(though subtle at the Level 1 portal).

Metal concentrations follow two types of temporal 

patterns (fig. 11). Zinc and Cd follow an apparently dilutioncontrolled pattern similar to SC and the major ions. Lead and 

Cu follow an apparently pH-controlled pattern, with concentrations inversely correlated with pH. Lead and Cu thus rise 

rather than fall during spring high flows. Dissolved concentrations of Pb and Cu are known to be pH-sensitive; when the pH 

drops below 4–5, these metals transition from a mainly sorbed 

state (onto suspended sediment particles) to a mainly dissolved 

state (Dzombak and Morel, 1990). The same temporal patterns 

for Zn, Cd, Pb, and Cu were observed for in 2007. Manganese at the Level 1 portal is apparently dilution-controlled, 

as observed in 2007. However, Mn at site EC-CELK2 follows a pattern that is apparently both dilution-controlled and 

pH-controlled, the former dominating late in the runoff cycle 

and the latter dominating early in the runoff cycle. Zinc and 

Cd concentrations increase slightly at the onset of snowmelt, 

as seen in 2007, suggesting that the low-pH water mobilized 

early in the snowmelt period is also elevated in Zn and Cd. 

The source of this water is unknown (Manning and others, 

2008), but it could be water within the mine workings that is 

relatively immobile during the rest of the year (and exposed 

to oxygen), such as water in muck/debris piles or in stagnant 

puddles on the tunnel floors.

Temporal patterns in Zn, Cd, and Mn concentrations in 

Elk Creek display notable differences in 2007 and 2010. In 

2007, these metals spiked during spring runoff. In 2010, they 

decreased at EC-CELK2 and remained essentially constant at 

EC-CELK1. As with the lower overall concentrations of these 

metals in 2010 (fig. 8), the absence of the spike during high 

flow in 2010 could be the result of either remedial efforts at 

the Standard Mine site or dilution caused by higher flows in 

2010 (fig. 4).

Manning and others (2008) hypothesized that Level 

1 portal discharge was the primary source of metals in Elk 

Creek based on temporal patterns in metal concentrations 

and on metal load estimates made using flow measurements 

from September 2006. Metal concentration patterns for the 

2010 samples (fig. 11) also are generally consistent with this 

hypothesis. Metal concentrations decrease with distance downstream from the Level 1 portal, and metals that decrease at the 

Level 1 portal during spring runoff also generally decrease in 
Results 13

(A) Sample Site EC-MSTD1 

pH

2007 2010

pH

2007 2010

SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER

Specific

Conductance

0

20

40

60

80

100 Ca

2007 2010

Ca, IN MILLIGRAMS PER LITER

100

150

200

250

300

350 SO4

2007 2010

SO4, IN MILLIGRAMS PER LITER

8

12

16

20

24

28

0.08

0.10

0.12

0.14

0.16

2

4

6

8

10

12 Zn

2007 2010

Zn, IN MILLIGRAMS PER LITER

Cd

2007 2010

Cd, IN MILLIGRAMS PER LITER

Mn

2007 2010

Mn, IN MILLIGRAMS PER LITER

0.0

0.4

0.8

1.2

1.6

2.0 Pb

2007 2010

Pb, IN MILLIGRAMS PER LITER

0.0

0.4

0.8

1.2 Cu

2007 2010

Cu, IN MILLIGRAMS PER LITER

2

3

4

5

6

7

300

400

500

600

700

(B) Sample Site EC-CELK1 

Figure 8

10

20

30

40

50 SO4

2007 2010

SO4, IN MILLIGRAMS PER LITER

pH

2007 2010

pH

2007 2010

SPECIFIC CONDUCTANCE, IN

MICROSIEMENS PER CENTIMETER

Specific

Conductance

5

10

15

20

25

30 Ca

2007 2010

Ca, IN MILLIGRAMS PER LITER

0.2

0.4

0.6

0.8

1.0 Zn

2007 2010

Zn, IN MILLIGRAMS PER LITER

0.001

0.002

0.003

0.004

0.005 Cd

2007 2010

Cd, IN MILLIGRAMS PER LITER

0.00

0.04

0.08

0.12

0.16

0.20 Mn

2007 2010

Mn, IN MILLIGRAMS PER LITER

0.000

0.002

0.004

0.006

0.008 Pb

2007 2010

Pb, IN MILLIGRAMS PER LITER

0.000

0.004

0.008

0.012

0.016 Cu

2007 2010

Cu, IN MILLIGRAMS PER LITER

5.5

6.0

6.5

7.0

7.5

40

80

120

160

200

Figure 8. Box-and-whisker plots comparing 2007 and 2010 measurements at sample site EC-MSTD1 (A) and sample site 

EC-CELK1 (B). Each year includes six samples.
14 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

2

3

4

5

6

7

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

4

5

6

7

8

3/15 4/1 4/15 5/1 5/15 6/1 6/15

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

pH

DATE

FLOW, IN CUBIC FEET

PER SECOND

A

7/1

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

DATE

FLOW, IN CUBIC FEET

PER SECOND

B

200

300

400

500

600

700

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0

50

100

150

200

250

3/15 4/1 4/15 5/1 5/15 6/1 6/15

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Figure 9

7/1

Figure 9. pH (A) and specific conductance (B) plotted versus sample date. Flows at the Level 1 portal the ELK-00 gage are 

shown for reference.

0

20

40

60

80

100

120

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0

5

10

15

20

25

30

35

3/15 4/1 4/15 5/1 5/15 6/1 6/15

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Ca, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

A

7/1

50

100

150

200

250

300

350

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0

10

20

30

40

50

60

70

80

90

3/15 4/1 4/15 5/1 5/15 6/1 6/15

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

SO4, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

B

7/1

Figure 10. Calcium (A) and sulfate (B) concentration plotted versus sample date. Flows at the Level 1 portal the ELK-00 gage 

are shown for reference.
Results 15

5

10

15

20

25

30

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0.0

0.5

1.0

1.5

2.0

2.5

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Zn, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

A

3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0.000

0.002

0.004

0.006

0.008

0.010

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Cd, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

B

3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

2

4

6

8

10

12

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0.00

0.05

0.10

0.15

0.20

0.25

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

CMn, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

0.0

0.4

0.8

1.2

1.6

2.0

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Pb, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

D

3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

EC-MSTD1 Level 1 Portal Flow

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0

5

10

15

20

25

30

EC-CELK1 EC-CELK2 ELK-00 Flow

Cu, IN MILLIGRAMS

PER LITER

DATE

FLOW, IN CUBIC FEET

PER SECOND

E

3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

Figure 11. Zinc (A), cadmium (B), manganese (C), lead (D), 

and copper (E) concentration plotted versus sample date. Only 

samples with concentrations above detection limit are shown. 

Flows at the Level 1 portal the ELK-00 gage are shown for 

reference.
16 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

0

20

40

60

80

100

120

140

160

EC-MSTD1

EC-CELK1

3/28 4/22 5/6 5/23 6/9 6/21

AZn LOAD, IN MILLIGRAMS

PER SECOND

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

EC-MSTD1

EC-CELK1

3/28 4/22 5/6 5/23 6/9 6/21

BCd LOAD, IN MILLIGRAMS

PER SECOND

0

5

10

15

20

25

30

EC-MSTD1

EC-CELK1

3/28 4/22 5/6 5/23 6/9 6/21

CMn LOAD, IN MILLIGRAMS

PER SECOND

0

1

2

3

4

5

6

7

8

9

EC-MSTD1

EC-CELK1

3/28 4/22 5/6 5/23 6/9 6/21

DPb LOAD, IN MILLIGRAMS

PER SECOND

0

1

2

3

4

5

6

7

EC-MSTD1

EC-CELK1

3/28 4/22 5/6 5/23 6/9 6/21

ECu LOAD, IN MILLIGRAMS

PER SECOND

Figure 12. Bar charts showing calculated loads for zinc (A), 

cadmium (B), manganese (C), lead (D), and copper (E). Loads 

were computed for sampling sites EC-CELK1 and EC-MSTD1 for 

each sampling event.

Elk Creek, and vice versa (Mn excepted). The availability of 

continuous flow data at both the Level 1 portal and ELK-00 

for the spring of 2010 allows for a more rigorous evaluation 

of this hypothesis by examining metal loads. Loads were 

computed for EC-MSTD1 and EC-CELK1 for each of the six 

sampling times using dissolved metal concentrations along 

with flows from the Level 1 portal gage and ELK-00 gage 

(located several hundred feet downstream from EC-CELK1) 

recorded within 15 minutes of the sampling time. If the Level 

1 portal is the primary metal source to Elk Creek, metal loads 

at EC-CELK1 should be similar to or less than loads at ECMSTD1. Metal loads for the two sample sites are compared 

in figure 12. For the more conservative metals Zn and Cd (not 

pH-sensitive), loads at EC-CELK1 are greater than at ECMSTD1 for five of the six sampling events. For Mn, Pb, and 

Cu, loads at EC-CELK1 are generally less than at EC-MSTD1. 

However, these metals are pH-sensitive so this could be due to 

pH differences at the two sites (pH ≥6 at EC-ELK1 versus pH 

3-5 at EC-MSTD1). The load results thus suggest that metals 

in Elk Creek during spring runoff may have sources other than 

the Level 1 portal. Discrepancies between Zn and Cd loads at 

the two sites generally decrease throughout the spring. This 

trend is consistent with the additional metal source(s) being 

located lower in the watershed, given that snowmelt sourced at 

lower elevation should compose a progressively smaller fraction of streamflow through the runoff period.
Results 17

Two potential sources of error in the calculated loads 

include (1) the assumption that loads remained constant 

throughout the sample day (that is, neglecting possible diurnal 

variations in load), and (2) errors in the flow measurements. 

Samples were collected within about four hours of each other 

for each sampling event, and collected in downstream order 

(EC-MSTD1 first, EC-CELK1 last), minimizing the possibility of large errors due to diurnal load variations. The magnitude of the flow measurement uncertainty is unknown and may 

be large, but probably not large enough to completely account 

for observed differences in Zn and Cd loads between the two 

sites. Nonetheless, all calculated loads should be interpreted 

with some caution.

Calculated loads can also be used to evaluate the possibility discussed above that lower metal concentrations at 

EC-CELK1 in 2010 compared to 2007 are due simply to 

higher flows in Elk Creek in 2010, leading to greater dilution of portal discharge (assumed metal source). If this were 

the case, loads at EC-CELK1 would be similar to or greater 

than loads at EC-MSTD1. If not (i.e., if metals are being 

removed from portal discharge in the bioreactor), then loads 

at EC-CELK1 would be smaller. As previously discussed, 

loads for the conservative metals Zn and Cd at EC-CELK1 

are generally greater than loads at EC-MSTD1, suggesting 

that dilution alone could indeed explain the lower Zn and Cd 

concentrations in 2010. It is possible that the bioreactor has 

a larger affect on the Mn, Pb, and Cu because loads of these 

metals at EC-CELK1 are similar to or less than EC-MSTD1. 

However, as mentioned above, this also simply could be a 

pH effect. 

Oxygen-18 and Deuterium

Oxygen-18 and deuterium isotopic ratios (d18O and d2H) 

are presented in table 5. Figure 13 shows temporal trends in 

d18O and d2H at the three sites sampled in 2010, as well as 

2007 results and flow records for the Level 1 portal and ELK00 for reference. Discussion of these data focuses on d18O 

because d2

H displays very similar trends to d18O for the 2010 

samples, as expected. In 2007, d2H showed some differences 

from d18O, but the reason for these is not clear and discussion 

of them is beyond the scope of this report. 2010 d18O values 

generally become lighter (more negative) during spring high 

flows, following a trend that is very similar to the dilutioncontrolled trends displayed by SC, Ca, and SO4

 (figs. 9 and 

10). 2007 samples follow the same first-order trend. This is 

likely due to precipitation d18O values being generally heavier 

(less negative) in rain than in snow (Manning and others, 

2008). In early spring immediately before snowmelt, baseflow 

waters in Elk Creek and in Level 1 portal discharge are likely 

composed of a mixture of prior precipitation—that is, both 

rain and snow. During spring runoff, the fraction of snowmelt 

(from the current year) in high flow waters is much larger, 

making d18O values lighter.

A notable difference between the 2010 and 2007 d18O 

data is that 2010 values are lighter by 0.5 to 2 permil. This 

could be the result of annual variability in the isotopic 

composition of the snowpack caused by annual variability 

in dominant winter storm tracks. Another possible explanation is that the ratio of the current year’s SWE to the prior 

summer’s rain is larger for 2010 than 2007 according to 

measurements at the Schofield Pass SNOTEL site. For spring 

2007, total SWE was 29 inches and the prior summer’s rain 

totaled 15 inches resulting in a SWE/rain ratio of 1.9. For 

spring 2010, total SWE was 37 inches and the prior summer’s rain totaled 8 inches resulting in a SWE/rain ratio of 

4.6. Assuming that the prior summer’s rain is a major control 

on d18O values in the following baseflow period (more rain 

equals heavier), then the larger SWE/rain ratio for the spring 

of 2010 should result in lighter high-flow d18O values, as 

observed. Another difference between 2010 and 2007 results 

is that 2007 d18O values at EC-MSTD1 increased early in 

the runoff period before decreasing later during the highest 

flows. An explanation for this is not clear, but it also may 

be related to differences in fractions and/or timing of prior 

years’ rain and snow. 

Table 5. Oxygen-18 and deuterium results.

[R (appended to sample name), replicate sample]

Sample Name Sample

Date

d18O

(permil)

d2H

(permil)

EC-CELK1-10 3/28/10 -16.88 -123.7

EC-CELK1-11 4/22/10 -18.00 -129.4

EC-CELK1-12 5/6/10 -18.00 -128.4

EC-CELK1-13 5/23/10 -18.15 -131.0

EC-CELK1-14 6/9/10 -17.45 -130.1

EC-CELK1-15 6/21/10 -16.98 -124.9

EC-CELK2-01 3/28/10 -16.62 -121.8

EC-CELK2-02 4/22/10 -17.70 -128.4

EC-CELK2-03 5/6/10 -17.40 -126.4

EC-CELK2-04 5/23/10 -18.00 -131.4

EC-CELK2-05 6/9/10 -17.74 -130.0

EC-CELK2-06 6/21/10 -17.10 -125.8

EC-MSTD1-11 3/28/10 -16.58 -119.2

EC-MSTD1-12 4/22/10 -16.94 -122.7

EC-MSTD1-13 5/6/10 -16.75 -121.9

EC-MSTD1-14 5/23/10 -17.35 -124.2

EC-MSTD1-15 6/9/10 -17.84 -129.6

EC-MSTD1-15R 6/9/10 -17.92 -129.2

EC-MSTD1-16 6/21/10 -17.22 -124.8
18 Spring Runoff Water-Chemistry Data from the Standard Mine and Elk Creek, Gunnison County, Colorado, 2010

-18.0

-17.5

-17.0

-16.5

-16.0

-15.5

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

2010 EC-MSTD1 2007 EC-MSTD1 Level 1 Portal Flow

-18.5

-18.0

-17.5

-17.0

-16.5

-16.0

-15.5

2/15 3/1 3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

0

5

10

15

20

25

30

2010 EC-CELK1 2010 EC-CELK2

2007 EC-CELK1 ELK-00 Flow

18O, IN PER MIL

CALENDAR DAY

FLOW, IN CUBIC FEET

PER SECOND

A

2010 EC-MSTD1 2007 EC-MSTD1 Level 1 Portal Flow

2/15 3/1 3/15 4/1 4/15 5/1 5/15 6/1 6/15 7/1

2010 EC-CELK1 2010 EC-CELK2

2007 EC-CELK1 ELK-00 Flow

2H, IN PER MIL

CALENDAR DAY

FLOW, IN CUBIC FEET

PER SECOND

B

-132

-128

-124

-120

-116

-112

-108

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

-136

-132

-128

-124

-120

-116

-112

0

5

10

15

20

25

30

Figure 13

Figured 13. δ18O (A) and δ2H (B) values plotted versus calendar day of sample collection. 2007 results at EC-MSTD1 and 

EC-CELK1, along with 2010 flows at the Level 1 portal the ELK-00 gage, are shown for reference.
References Cited 19

Conclusions

1. Field parameter values (pH and specific conductance), 

major ion concentrations (calcium and sulfate), and metal 

concentrations (zinc, cadmium, manganese, lead, and 

copper) in Level 1 portal discharge are similar to those in 

2007 reported by Manning and others (2008). For samples 

collected at sample site EC-CELK1 near the mouth of Elk 

Creek, field parameter values and major ion concentrations measured in 2010 and 2007 are similar, but 2010 

metal concentrations are lower. These lower concentrations could be due either to remedial activities performed 

at the Standard Mine site between 2007 and 2010, or to 

greater dilution of Level 1 portal discharge in 2010 caused 

by higher Elk Creek flows.

2. Temporal patterns in field parameters, major ion concentrations, and metal concentrations during the 2010 spring 

runoff period were similar to those in 2007 reported by 

Manning and others (2008). The pH, specific conductance, and major ion concentrations generally decreased 

during high flows. The pH of Level 1 portal discharge 

dropped from about 6 to about 3 in the early stages of 

snowmelt. Concentrations of zinc, cadmium, and manganese generally decreased during high flows and concentrations of lead and copper generally increased.

3. The 2010 data support the finding by Manning and others 

(2008) that two primary factors control metal concentrations in Level 1 portal discharge and Elk Creek: dilution 

and pH. Zinc and cadmium concentrations are apparently 

dilution-controlled, being inversely proportional to streamflows. Lead and copper concentrations are apparently pHcontrolled, being inversely proportional to pH and poorly 

correlated with streamflows. Manganese concentrations 

may be either dilution-controlled or pH-controlled, depending on sample location and time within the runoff period.

4. Calculated zinc and cadmium loads near the mouth of 

Elk Creek (EC-CELK1) are generally greater than loads 

at the Level 1 portal. This suggests that another source of 

zinc and cadmium in addition to the Level 1 portal might 

exist for Elk Creek during the spring runoff period. This 

also suggests that the lower metal concentrations measured near the mouth of Elk Creek (EC-CELK1) in 2010 

compared to 2007 could be explained solely by greater 

dilution in 201 However, uncertainties in the calculated 

loads are not well characterized and could be substantial.

5. d18O values are well correlated with flow, becoming lighter 

(more negative) during spring high flows in both Level 1 

discharge and Elk Creek. The distinct seasonal drop in d18O 

in Level 1 discharge, along with portal flow tracking very 

closely with creek flow, is consistent with geochemical 

and environmental tracer data collected by Manning and 

others (2008) indicating short residence times (<1 year) for 

groundwater discharging from the Standard Mine.

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sulfate in natural water using ion chromatography: U.S. 

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