U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 00–4154

Determination of Instream Metal Loads 

Using Tracer-Injection and SynopticSampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

By Roderick F. Ortiz and Kenneth E. Bencala

Denver, Colorado

2001

Prepared in cooperation with the

U.S. ENVIRONMENTAL PROTECTION AGENCY and the

COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
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 this report is for identification purposes only and does

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

For additional information write to: Copies of this report can be purchased

U.S. Geological Survey

Information Services

Box 25286

Federal Center

Denver, CO 80225

from:

District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046
CONTENTS III

CONTENTS

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

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

Purpose and Scope....................................................................................................................................................... 3

Description of Study Area ........................................................................................................................................... 3

Acknowledgments ....................................................................................................................................................... 6

Study Approach ..................................................................................................................................................................... 6

Background Chloride and Streamflow Conditions...................................................................................................... 6

Tracer Injection............................................................................................................................................................ 8

Synoptic Sampling....................................................................................................................................................... 9

Tracer-Injection and Synoptic-Sampling Results .................................................................................................................. 9

Chloride Flux ............................................................................................................................................................... 9

Chloride Profiles .......................................................................................................................................................... 10

Discharge Profiles........................................................................................................................................................ 10

Synoptic-Sampling Results.......................................................................................................................................... 12

Metal Loads ........................................................................................................................................................................... 14

Primary Study Reach ................................................................................................................................................... 14

Secondary Study Reach ............................................................................................................................................... 17

Summary................................................................................................................................................................................ 18

References Cited.................................................................................................................................................................... 20

Appendix................................................................................................................................................................................ 21

FIGURES

1. Map showing location of Summitville Mine site........................................................................................................ 2

2. Map showing location of injection site, selected sampling sites on Wightman Fork, and selected inflow 

sites to Wightman Fork ............................................................................................................................................... 4

3–9. Graphs showing:

3. Background and synoptic chloride concentrations in Wightman Fork, September 16–19, 1997 ...................... 7

4. Discharge at U.S. Geological Survey streamflow-gaging station 08235270, September 16–19, 1997 ............. 7

5. Chloride concentrations at selected transport sites in Wightman Fork during tracer-injection and 

synoptic-sampling study, September 16–19, 1997............................................................................................. 8

6. Mass flux of chloride into Wightman Fork during continuous injection, September 17–19, 1997................... 10

7. Chloride concentrations in Wightman Fork attributable to tracer injection, September 18 and 19, 1997......... 11

8. Discharge profiles in Wightman Fork during synoptic sampling, September 18 and 19, 1997......................... 12

9. pH profiles in Wightman Fork and inflow sites, September 18 and 19, 1997 ................................................... 14

10. Mass-load profiles for dissolved aluminum and copper in Wightman Fork, September 18 and 19, 1997................. 15

11. Mass-load profiles for dissolved iron and manganese in Wightman Fork, September 18 and 19, 1997.................... 16

12. Mass-load profile for dissolved zinc in Wightman Fork, September 18 and 19, 1997............................................... 17

TABLES

1. Site locations for tracer-injection and synoptic-sampling study in Wightman Fork at the 

Summitville Mine site, September 18 and 19, 1997 ............................................................................................... 5

2. Estimated discharge, pH, dissolved metal concentrations, and calculated dissolved metal loads 

in Wightman Fork at the Summitville Mine site, September 18 and 19, 1997 ....................................................... 13

3. Increase in metal loads along a selected stream reach of Wightman Fork, and percentage of 

load from selected stream reach when compared to loads at the end of the primary study reach, 

September 18, 1997................................................................................................................................................. 18

4. Change in metal loads along selected stream reaches of Wightman Fork, and percentage of load 

from selected stream reaches when compared to loads at the end of the secondary study reach, 

September 19, 1997................................................................................................................................................. 18
IV CONTENTS

5. Summary of dissolved metal loading for selected source areas along Wightman Fork to downstream 

end of primary and secondary study reaches, September 18 and 19, 1997 ............................................................ 19

6. Site locations, specific conductance, and pH for inflows to Wightman Fork during tracer-injection 

and synoptic-sampling study, September 18 and 19, 1997 ..................................................................................... 23

7. Selected chemical data for synoptic samples collected from inflow sites to Wightman Fork during 

the tracer-injection and synoptic-sampling study on Wightman Fork, September 18 and 19, 1997 ...................... 24

8. Selected chemical data for synoptic samples collected from Wightman Fork during the tracer-injection 

and synoptic-sampling study on Wightman Fork, September 18 and 19, 1997...................................................... 26

CONVERSION FACTORS AND ACRONYMS

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived 

from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.

Acronyms used in this report:

USEPA United States Environmental Protection Agency

CDPHE Colorado Department of Public Health and Environment

SWTF Summitville Water Treatment Facility

NWD North Waste Dump

SDI Summitville Dam Impoundment

USGS United States Geological Survey

Multiply By To obtain

liter 0.2642 gallon

liters per second 0.0353 cubic feet per second

kilogram 2.205 pound

milliliter 0.0339 ounce

milligram 0.00003527 ounce

micrometer 0.0000394 inch
Abstract 1

Abstract

Spatial determinations of the metal loads in 

Wightman Fork can be used to identify potential 

source areas to the stream. In September 1997, a 

chloride tracer-injection study was done concurrently with synoptic water-quality sampling in 

Wightman Fork near the Summitville Mine site. 

Discharge was determined and metal concentrations at 38 sites were used to generate mass-load 

profiles for dissolved aluminum, copper, iron, 

manganese, and zinc. The U.S. Environmental 

Protection Agency had previously identified these 

metals as contaminants of concern.

Metal loads increased substantially in 

Wightman Fork near the Summitville Mine. 

A large increase occurred along a 60-meter 

reach that is north of the North Waste Dump 

and generally corresponds to a region of 

radial faults. Metal loading from this reach 

was equivalent to 50 percent or more of the 

dissolved aluminum, copper, iron, manganese, 

and zinc load upstream from the outfall of the 

Summitville Water Treatment Facility (SWTF). 

Overall, sources along the entire reach upstream 

from the SWTF were equivalent to 15 percent of 

the iron, 33 percent of the copper and manganese, 

58 percent of the zinc, and 66 percent of the 

aluminum load leaving the mine site. The largest 

increases in metal loading to Wightman Fork 

occurred as a result of inflow from Cropsy Creek.

Aluminum, iron, manganese, and zinc loads from 

Cropsy Creek were equivalent to about 40 percent 

of the specific metal load leaving the mine site. 

Copper, iron, and manganese loads from Cropsy 

Creek were nearly as large or larger than the load 

from sources upstream from the SWTF.

INTRODUCTION

The Summitville Mine site is located at an 

elevation of 11,500 feet above sea level in the San Juan 

Mountains of southwestern Colorado (fig. 1). Historically, the site was operated as an underground gold 

mine. Mine-drainage waters from the Summitville 

Mine are among the most acidic and metal rich in 

Colorado (Plumlee and others, 1995). High concentrations of aluminum, copper, iron, zinc, and several 

other metals are present in Wightman Fork. In 1992, 

the operating company abandoned the mine site, and 

the U.S. Environmental Protection Agency (USEPA) 

assumed responsibility for cleanup and remediation of 

the newly designated Superfund site. The Colorado 

Department of Public Health and Environment 

(CDPHE) assumed shared management responsibilities for the Summitville Mine site with the USEPA in 

1998.

Remedial strategies at the mine site have 

focused on two main objectives: (1) reduction of 

acid-mine drainage by decreasing exposure of sulfide 

minerals to air and water; and (2) capture and treatment of the acid mine drainage before it reaches 

Wightman Fork. Major remediation efforts at the site 

have included plugging several mine adits, relocating 

waste material to the mine pits, capping the mine pits 

Determination of Instream Metal Loads Using

Tracer-Injection and Synoptic-Sampling Techniques

in Wightman Fork, Southwestern Colorado,

September 1997

By Roderick F. Ortiz and Kenneth E. Bencala
2 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

0 1/4 1/2 MILE

0 0.25 0.5 KILOMETER

Mine Pit Area

Iowa Adit

Reynolds

Adit

Chandler Adit

Summitville Water

Treatment Facility

Summitville Dam

Impoundment

Former Cropsy

Waste Pile

Heap Leach

Pad

Former Beaver

Mud Dump

North Waste

Dump

37°18'

37°18'30"

106°36' 106°35'

Base modified from Morrison Knudsen Corporation, 1997

Albers Equal-Area Conic Projection

Standard Parallels 37°30' N and 40°30' N Central Meridian 105°30' W

DENVER

Alamosa

Summitville Mine

Pipeline Creek

Wightman Fork

Cropsy Creek

Approximate

Boundary of

Summitville

Mine Site

Figure 1. Location of Summitville Mine site.
INTRODUCTION 3

and the heap leach pad, increasing the storage capacity 

of impoundment structures, and increasing the 

capacity of the Summitville Water Treatment Facility 

(SWTF). Remediation efforts at the Summitville Mine 

have resulted in a large decrease in metal loads1

discharging from the old mine workings (Morrison 

Knudsen Corporation, 1997). Although remediation 

efforts at the Summitville Mine site have been relatively successful, areas of concern still exist. 

Metal loads from upper Wightman Fork could 

be a significant part of the total load leaving the mine 

site. Historical ferricrete masses (a hard conglomerate 

of sand and gravel cemented by iron oxide) along the 

northern boundary of the mine site indicate that the 

North Waste Dump (NWD) (fig. 1) represented a 

substantial source of acid drainage to Wightman Fork. 

Large amounts of sulfidic waste rock are still present 

in the NWD. Along the toe of the NWD, springs 

related to a northwest/southeast-trending fault escarpment are apparent (Morrison Knudsen Corporation, 

1997). Seepage around the plugged Chandler Adit 

(fig. 1) and seeps adjacent to, and hydraulically 

downgradient from, the adit also could be a potential 

source of metals to upper Wightman Fork (Morrison 

Knudsen Corporation, 1997). Although a collection 

system along the northern perimeter of the mine 

site redirects surface water to the Summitville Dam 

Impoundment (SDI) (fig. 1), results of previous waterquality sampling have shown that high concentrations 

of metals are present in upper Wightman Fork (J. Fox, 

Environmental Chemical Corporation, written 

commun., 1998). Effluent from the SWTF represents a point source of metal load to Wightman Fork; 

however, metal concentrations generally were low 

in this water (Environmental Chemical Corporation, 

1998). Cropsy Creek, which flows along the southern 

and eastern boundary of the mine site, is in close proximity to the heap leach pad; numerous acidic seeps 

have been identified downgradient from the heap leach 

pad (Morrison Knudsen Corporation, 1997).

In 1997, the U.S. Geological Survey (USGS), 

in cooperation with the USEPA and the CDPHE, 

investigated metal loading in Wightman Fork at 

the Summitville Mine site by using tracer-injection 

and synoptic-sampling techniques. By determining 

discharge and tracer concentration at multiple sites, 

investigators provided a detailed understanding of 

source areas to upper Wightman Fork. The resulting 

mass-loading profiles would allow the USEPA and the 

CDPHE to identify and target source areas for future 

remediation efforts at the Summitville Mine site. 

Purpose and Scope

This report describes the results of a tracerinjection and synoptic-sampling study conducted 

September 16–19, 1997, to identify and quantify 

sources of metal loading to Wightman Fork adjacent 

to the Summitville Mine site. Metal loads were calculated using (1) discharge data derived from a continuous chloride injection and (2) concentration data 

collected during synoptic water-quality sampling. 

The report quantifies metal loads and pH at 38 sites 

in Wightman Fork from near the headwaters to the 

eastern boundary of the mine site. The study reach is 

2,815 meters long. Mass-loading profiles were generated for aluminum, copper, iron, manganese, and zinc 

along two study reaches.

Description of Study Area

Wightman Fork flows east along the northern 

perimeter of the Summitville Mine site (fig. 1). The 

study area consisted of two contiguous reaches on 

Wightman Fork. The primary study reach extended 

1,748 meters from near the headwaters to just 

upstream from the SWTF outfall (fig. 2). Quantification of metal loads upstream from the SWTF were 

of greatest interest to the cooperators since available 

data were limited and the metal loading profile of 

Wightman Fork in this reach was largely unknown. 

Thirty-four main-stem sites, including a background 

site (WF_BG), were located in the primary reach 

(table 1). Sites were selected to provide good spatial 

resolution of the metal loading in Wightman Fork. 

Pipeline Creek is the largest tributary along the 

primary reach, although several small tributaries, 

springs, and seeps also exist. Ground-water inflow 

most likely occurs as well. 

The secondary reach extended from just 

upstream of the SWTF outfall to the USGS gaging 

station (08235270; site WF_2,815m) at the eastern 

boundary of the mine site (fig. 2). Only six mainstem sites were located along this 1,067-meter reach 

1Load is defined as the mass of a target analyte in the stream 

per unit time and is the product of analyte concentration and 

discharge.
4 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork,

Southwestern Colorado, September 1997

WF_1,592mWT_2,757m

WF_BG

WT_25m

WF_592m

WF_802m WF_954m WT_596m

WT_807m

WT_829m

WT_845m WF_1,332m

WF_1,645m

WF_1,748m

WF_1,807m

WF_2,755m WF_2,815m

WT_1,267m

WT_1,759m(Pump HouseFault) WT_2,757m

WT_1,774mWT_1,777mSummitville WaterTreatment Facility

EXPLANATION

Wightman Fork sampling site and numberInflow sampling site and number

Mine Pit Area

North Waste

Dump

Former Beaver

Mud Dump

Heap Leach

Pad

Summitville

Dam Impoundment

Primary Reach Secondary Reach

37°18'30"

106°36' 106°35'

37°18'

Base modified from Morrison Knudsen Corporation, 1997Albers Equal-Area Conic ProjectionStandard Parallels 37°30' N and 40°30' N

Central Meridian 105°30' W

WF0m(InjectionPoint)

keer Cenil epi P

Wightman Fork

Cropsy

Creek

0 0.1 0.2 0.3 MILE0 0.1 0.2 0.3 KILOMETER

Figure 2. Location of injection site, selected sampling sites on Wightman Fork, and selected inflow sites to Wightman Fork.
INTRODUCTION 5

Table 1. Site locations for tracer-injection and synoptic-sampling study in Wightman Fork at the Summitville Mine site, 

September 18 and 19, 1997

[NA, not applicable; USEPA, U.S. Environmental Protection Agency; SDI, Summitville Dam Impoundment; USGS, U.S. Geological Survey; shaded area 

denotes extent of secondary study reach]

Site identification

and transport 

site number

Sampling 

date

Sampling 

time

Distance from 

injection site 

(meters)

Stream 

reach

Description of 

site location or 

stream characteristics

WF_BG 09–18–97 1520 –7 NA Background site; unaffected by injection

WF_0m NA NA 0 NA Injection point

WF_13m (T1) 09–18–97 1515 13 Primary First transport site: upstream from tributary

WF_31m 09–18–97 1505 31 Primary Downstream from tributary

WF_54m 09–18–97 1500 54 Primary Grayish-white precipitate apparent

WF_145m 09–18–97 1445 145 Primary Deeply cut channel in tundra

WF_265m 09–18–97 1435 265 Primary Middle of grassy meanders

WF_445m 09–18–97 1425 445 Primary

WF_592m 09–18–97 1355 592 Primary Upstream from Pipeline Creek

WF_622m 09–18–97 1345 622 Primary Downstream from Pipeline Creek

WF_682m (T2) 09–18–97 1340 682 Primary Second transport site

WF_742m 09–18–97 1330 742 Primary Less precipitates on stream bottom

WF_802m 09–18–97 1320 802 Primary Aluminum precipitates very apparent

WF_817m 09–18–97 1310 817 Primary White precipitate present; no orange floc

WF_832m 09–18–97 1305 832 Primary Orange floc downstream from site

WF_862m (T3) 09–18–97 1250 862 Primary Third transport site

WF_890m 09–18–97 1245 890 Primary

WF_922m 09–18–97 1205 922 Primary Algae apparent

WF_954m 09–18–97 1200 954 Primary Abiotic floc: previous site USEPA WF2

WF_993m 09–18–97 1145 993 Primary

WF_1,042m 09–18–97 1135 1,042 Primary Algae and floc apparent

WF_1,083m 09–18–97 1130 1,083 Primary Green algae

WF_1,102m (T4) 09–18–97 1100 1,102 Primary Fourth transport site

WF_1,131m 09–18–97 1055 1,131 Primary Upstream from old dam structure

WF_1,163m 09–18–97 1045 1,163 Primary Downstream from old dam structure; less floc

WF_1,214m 09–18–97 1040 1,214 Primary Less algae

WF_1,259m 09–18–97 1017 1,259 Primary Upstream from unnamed tributary

WF_1,274m 09–18–97 1010 1,274 Primary Downstream from unnamed tributary

WF_1,332m 09–18–97 1000 1,332 Primary

WF_1,392m 09–18–97 0955 1,392 Primary Sparse algae

WF_1,485m 09–18–97 0950 1,485 Primary

WF_1,599m 09–18–97 0935 1,599 Primary

WF_1,645m 09–18–97 0930 1,645 Primary Bromide spot injection location

WF_1,748m (T5) 09–18–97 0920 1,748 Primary Upstream from treatment facility outfall

WF_1,748m (T5) 09–19–97 1040 1,748 Secondary Fifth transport site

WF_1,807m 09–19–97 1020 1,807 Secondary Downstream from treatment facility outfall

WF_1,964m 09–19–97 1005 1,964 Secondary Upstream from unnamed tributary

WF_2,384m 09–19–97 0950 2,384 Secondary Before culvert at SDI dam

WF_2,755m 09–19–97 0930 2,755 Secondary Upstream from Cropsy Creek

WF_2,815m (T6) 09–19–97 0920 2,815 Secondary At USGS streamflow-gaging station 08235270
6 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

(table 1). Discharge from the SWTF and Cropsy 

Creek are the most significant inflows along the 

secondary reach. Discharge at the gaging station 

during September generally ranged from 85 to 

170 liters per second (Crowfoot and others, 1997, 

1998).

Site WF_1,748m was included in both study 

reaches; it represented the downstream end of the 

primary study reach and the upstream end of the 

secondary reach. The site was used for comparison 

of metal loads between the two reaches. Thirty-eight 

inflow sites also were sampled as part of the study plan 

(table 6 in the Appendix at the back of report). All 

sampling sites were identified by a two-letter prefix 

and the measured distance (in meters) downstream 

from the injection point (WF_0m). Main-stem sites 

are designated by the prefix WF and inflow sites are 

designated by the prefix WT. Only those sites that 

were specifically addressed in the report are shown 

in figure 2.

Acknowledgments

The authors thank Briant Kimball, Robert 

Runkel, Katherine Walton-Day, Robert Broshears, 

Jonathan B. Evans, Tracy B. Yager, and Fred Rossi 

of the USGS Toxic Substances Hydrology Program 

for their assistance in the collection of the data used 

in this report. Special thanks to Sheryl Ferguson and 

Robert Stogner of the USGS for effort and assistance 

during the study.

STUDY APPROACH

Tracer-injection and synoptic-sampling techniques are well suited for the determination of source 

loading in small mountain streams. Discharge can be 

measured with good precision by adding a conservative salt tracer to a stream and calculating discharge 

from the amount of dilution as the tracer moves downstream (Bencala and others, 1990; Kimball, 1997). By 

controlling the concentration of the salt tracer and the 

rate at which it is added to the stream, the mass of 

salt added to the stream is known (Zellweger and 

others, 1988). Discharges can then be calculated by 

measuring the concentration of the tracer upstream 

and downstream from the injection point and using 

conservation of mass to derive the discharge (Kimball 

and others, 1999a). Coupled with synoptic waterquality sampling, a detailed spatial determination of 

the loading in the stream can be generated and source 

areas contributing the greatest loads can be identified 

for remedial action (Kimball, 1997; Kimball and 

others, 1999b).

Background Chloride and Streamflow 

Conditions

A tracer is usually chosen because the addition 

of a reasonable amount of the tracer into the stream 

dominates the relatively low background concentration 

of the tracer already present in the water. Chloride was 

selected as the injection tracer even though the spatial 

variability of chloride in the study reach was mostly 

unknown. However, previous data had shown chloride 

concentrations at site WF_2,815m to be about 4 to 

6 milligrams per liter (S.A. Ferguson, U.S. Geological 

Survey, oral commun., 1998). In order to quantify the 

background chloride concentrations in Wightman 

Fork, a presynoptic sampling for chloride was 

conducted the day before the start of the chloride 

tracer injection. Background chloride samples were 

collected at 29 main-stem synoptic sampling sites 

(fig. 3). Chloride concentrations were estimated for 

nine additional sites where no samples were collected 

or analytical values were suspect. Background concentrations along the primary study reach ranged from 

0.24 to 2.69 milligrams per liter. An increase in chloride concentration occurred at the SWTF and persisted 

throughout the secondary reach; background chloride 

concentrations ranged from 2.69 to 4.84 milligrams 

per liter. Nevertheless, background chloride concentrations in Wightman Fork were substantially lower than 

synoptic chloride concentrations.

An assumption was made that discharge in 

Wightman Fork upstream from the SWTF was similar 

during the presynoptic (September 16) and synoptic 

(September 18) sampling periods. The assumption 

was based on the lack of appreciable rainfall at the 

mine site during this period (B.T. Marshall, Rocky 

Mountain Consultants Inc., written commun., 2000) 

and the base discharge conditions at the site. A change 

in discharge, however, did occur along the secondary 

study reach due to discontinuous operations at the 

SWTF (fig. 4). Synoptic samples along this reach were 

not collected until the discharge had returned to levels 

similar to those observed during the presynoptic 

(background) sampling. As such, synoptic sampling 

along the secondary reach did not occur until 

September 19, 1997.
STUDY APPROACH 7

Note: Synoptic chloride for WF_13m

was 232 milligrams per liter

500 1,000 1,500 2,000 2,500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

0

160

20

40

60

80

100

120

140

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

Synoptic concentration (September 18–19, 1997)

Background concentration (September 16, 1997)

Estimated background concentration

0

0600 1200 1800 2400 0600 1200 1800 2400 0600 1200 1800 2400 0600 1200 1800

16 17 18 19

September 1997

Approximate sampling time on September 19

along secondary study reach

Approximate sampling time on September 16

for presynoptic chloride samples

70

150

80

90

100

110

120

130

140

DISCHARGE, IN LITERS PER SECOND

Figure 3. Background and synoptic chloride concentrations in Wightman Fork, September 16–19, 1997.

Figure 4. Discharge at U.S. Geological Survey streamflow-gaging station 08235270, September 16–19, 1997.
8 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Tracer Injection

A simultaneous injection of sodium chloride 

(NaCl) and lithium chloride (LiCl) solutions began 

at 11:00 a.m. on September 17, 1997. The two salts 

were selected as injectates for various reasons, but 

for the purpose of this report, only chloride is 

discussed. Metered injection pumps were operated in 

parallel to deliver the two salt solutions at specified 

rates. Initial injection rates were 512 milliliters per 

minute of NaCl and 105 milliliters per minute of LiCl. 

Samples of the two injectates were collected from the 

pumps at the start of the injection to quantify the initial 

chloride flux2

 to the stream. The chloride flux is 

additive because chloride is present in both salts. Eight 

sets of injectate samples were collected during the 

course of the continuous injection to quantify the chloride flux. 

Multiple chloride samples were collected at six 

transport sites (T1–T6) on Wightman Fork (table 1). 

The samples were used to quantify traveltimes in 

Wightman Fork and to confirm that tracer chloride 

concentrations had reached a plateau in the stream 

prior to and during synoptic sampling. Figure 5 

illustrates the typical pattern observed at the transport 

sites. The continuous injection was terminated, after 

46 hours, at 9:00 a.m. on September 19, 1997.

A spot injection of sodium bromide was 

done upstream from the SWTF (site WF_1,645m) on 

September 19, 1997 (fig. 2). The spot injection was 

intended as an independent check of the discharge 

estimate at this site provided by the chloride tracer.

2Flux is defined as the mass of chloride (in milligrams) 

delivered per unit time (in seconds).

2400 0600 1200 1800 2400 0600 1200 1800 2400 0600 1200 1800 2400

17 18 19

September 1997

240

20

40

60

80

100

120

140

160

180

200

220

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

EXPLANATION

WF_13m (Transport site 1) WF_862m (Transport site 3) WF_2,815m (Transport site 6)

0

Figure 5. Chloride concentrations at selected transport sites in Wightman Fork during tracer-injection 

and synoptic-sampling study, September 16–19, 1997.
TRACER-INJECTION AND SYNOPTIC-SAMPLING RESULTS 9

Synoptic Sampling

Synoptic sampling provides a spatially detailed 

description of the water quality in a stream and is 

accomplished by sampling numerous sites in a relatively short time. Analysis of the synoptic samples 

provides both tracer-concentration data needed for 

estimation of discharge and concentration data for 

specific constituents needed for load calculations. 

Constituents of concern in Wightman Fork were pH, 

dissolved aluminum, copper, iron, manganese, and 

zinc. The following discussion focuses on these six 

parameters. Analytical data for other constituents are 

in table 8 in the Appendix at the back of the report. 

Two synoptic-sampling efforts were 

conducted during the continuous tracer injection. 

Including the background site, 33 sites were 

sampled on September 18, 1997, along the primary 

reach in Wightman Fork (table 1). In addition, 

30 inflow sites along this reach were sampled 

(table 6 and table 7 in the Appendix at the back 

of report). Samples were analyzed for anions, 

including chloride, and selected dissolved metals. 

In addition, specific conductance and pH were 

measured. Synoptic sampling was not done along 

the secondary study reach on September 18 because 

discharge from the SWTF was discontinuous at the 

time (fig. 4).

Synoptic sampling along the secondary study 

reach took place on September 19 after operations 

at the SWTF had reestablished routine discharge to 

Wightman Fork (fig. 4). Six sites were sampled in 

Wightman Fork; site WF_1,748m was resampled 

to provide a comparison of data collected on the 

previous day (table 1). Eight inflow sites were 

sampled (table 6 and table 7 in the Appendix at the 

back of report). Samples were analyzed for anions, 

including chloride, and selected dissolved metals. 

In addition, specific conductance and pH were 

measured.

Synoptic samples were collected in an 

upstream order to avoid potential contamination 

of sampling sites. Samples were collected in 3-liter 

plastic containers near the centroid of the stream by 

using grab-sample techniques. Samples were transported to a nearby laboratory area for immediate 

processing. Sample water for analysis of dissolved 

constituents was passed through 0.1-micrometer plate 

filters and preserved with nitric acid. All samples were 

packaged and transported to the USGS Utah District 

laboratory for analysis. 

Data-collection and analytical procedures 

used in this study incorporated practices designed 

to control, verify, and assess the quality of sample 

data. Methods and associated quality control for 

collection and processing of water samples are 

described by Horowitz and others (1994). In 

general, quality-assurance methods were comparable to those described in Kimball and others 

(1999a) and Cleasby and others (2000). A 5-percent 

error in analytical precision was assumed for all 

metals data (Briant Kimball, U.S. Geological 

Survey, oral commun.,1999).

TRACER-INJECTION AND SYNOPTICSAMPLING RESULTS

Metal loads are the product of stream 

discharge and concentration. Synoptic sampling 

provides the required concentration data. Estimation of discharge using tracer-injection techniques, 

however, requires additional data analysis. First, 

the chloride flux to the stream during the synoptic 

sampling must be determined. Second, downstream 

chloride concentrations attributable to the tracer 

needs to be established. Lastly, an appropriate equation is applied to calculate the discharge. The 

following sections will describe the methodology 

used to calculate metal loads in Wightman Fork on 

September 18 and 19, 1997.

Chloride Flux

Analysis of the mass flux data (injection rate 

times injectate concentration) indicated that the 

chloride flux was not constant during the 46-hour 

injection period (fig. 6). However, chloride flux was 

less variable on September 18 than any other period 

during the injection. As such, the flux measurements on September 18 were most representative of 

the chloride flux during synoptic sampling on that 

day since traveltime was less than 6 hours to the 

downstream end of the primary reach. An average 

flux of 1,053 milligrams per second was used to 

calculate discharge on September 18 along the 

primary study reach. One chloride flux measurement was made at 9:00 a.m. on September 19, 1997. 

Available pump data indicated that the pumping 

parameters at that time were similar to those 

observed 6 to 7 hours earlier. Given that traveltimes 
10 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Average chloride flux on September 18, 1997

Estimated chloride flux on September 19, 1997

Measured flux from September 17–19, 1997

600

2,000

800

1,000

1,200

1,400

1,600

1,800

CHLORIDE FLUX, IN MILLIGRAMS PER SECOND

2400 0600 1200 1800 2400 0600 1200 1800 2400 0600 1200 1800 2400

17 18 19

September 1997

along the secondary study reach were greater 

than 6 hours, this single flux measurement of 

902 milligrams per second generally was representative of the chloride flux during the synoptic 

sampling on September 19, 1997. 

Chloride Profiles

Chloride concentrations in Wightman 

Fork attributable to the tracer were determined by 

subtracting background concentrations from concentrations measured in the synoptic samples. The chloride differences (delta-chloride data) were smoothed 

to produce a chloride profile that showed decreasing 

concentration, or increasing discharge, in the downstream direction (fig. 7). Smoothing was accomplished 

by identifying sites in the stream where substantial 

decreases in chloride concentration occurred and 

identifiable tributary inflow (increased dilution) 

was observed. The concentrations at these Wightman 

Fork sites were used to delineate several subreaches 

or levels of chloride from highest to lowest concentration. A linear interpolation of the delta-chloride 

concentrations was done for intermediate sites along 

a subreach. The delta-chloride concentrations taken 

from the smoothed chloride profile were used to calculate stream discharges (fig. 7).

Discharge Profiles

Stream discharge at sampling points downstream from the injection is calculated by considering the injectate flux and the observed tracer 

concentrations (Broshears and others, 1993):

(1)

where

Q is the stream discharge,

CINJ is the tracer concentration in the injection 

solution,

QINJ is the rate of the tracer injection into the 

stream,

C is the tracer concentration measured in the 

synoptic sample, and

CP is the tracer concentration measured in the 

presynoptic sample.

Q QINJ CINJ ( ) C CP = ⁄ ( ) –

Figure 6. Mass flux of chloride into Wightman Fork during continuous injection, September 17–19, 1997.
TRACER-INJECTION AND SYNOPTIC-SAMPLING RESULTS 11

The denominator (C – Cp) in equation 1 

is the delta-chloride concentration described in 

the previous section. A discharge profile along 

the two study reaches was developed using 

equation 1 (fig. 8). The discharge at the first site 

downstream from the injection, Q, is used to calculate the discharge at the next site. The calculated 

discharge is then used as the upstream discharge in 

order to calculate the next downstream discharge, 

and so on.

Estimations of error were assigned for 

discharges on September 18 using the range in flux 

measured on that day. September 19 discharges were 

assigned an error of plus or minus 15 percent, which 

represents a worst case scenario given the variability 

in injection parameters on September 19, 1997. In 

addition, three instantaneous discharge measurements 

were done on September 19 along the secondary 

study reach (fig. 8). Only the measurement at 

site WF_2,815m was done during synoptic sampling.

The discharge estimate using the bromide spot injection represents conditions on September 19, whereas 

discharges in the primary study reach were calculated 

for conditions on September 18.

Discharge in Wightman Fork increased downstream nearly twentyfold along the 2,815-meter 

study reach. The major tributary inflows to the 

stream along the primary study area were Pipeline 

Creek (site WT_596m) and unnamed tributaries 

at sites WT_25m and WT_845m (fig. 8). In the 

secondary reach, inputs from the Summitville 

Water Treatment Facility (sites WT_1,774m and 

WT_1,777m) and Cropsy Creek (site WT_2,757m) 

composed nearly all the increase in discharge.

1,500 2,000 2,500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

Summitville Water Treatment Facility (WT_1,774m and WT_1,777m)

Inflow from unnamed tributary (WT_845m)

1,000

0

0 500

250

25

50

75

100

125

150

175

200

225

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

Inflow from unnamed tributary (WT_25m)

Smoothed chloride (September 18, 1997)

Smoothed chloride (September 19, 1997)

Concentration attributed to injection (September 18, 1997)

Concentration attributed to injection (September 19, 1997)

Inflow from Pipeline Creek (WT_596m)

Inflow from Cropsy Creek (WT_2,757m)

Figure 7. Chloride concentrations in Wightman Fork attributable to tracer injection, September 18 and 19, 1997.
12 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Synoptic-Sampling Results

Dissolved aluminum, copper, iron, manganese, 

and zinc concentrations in Wightman Fork exhibited 

similar downstream profiles (table 2). Metal concentrations upstream from Pipeline Creek were slightly 

elevated but decreased as relatively clean water 

from Pipeline Creek entered the stream. Between 

sites WF_802m and WF_862m, concentrations 

of the five metals increased by fourfold to as much 

as a hundredfold. Concentrations continued to 

increase, by varying degrees, between site WF_862m 

and site WF_1,214m before decreasing slightly 

downstream to site WF_1,332m. A relatively clean 

tributary (WT_1,267m) enters Wightman Fork 

in this reach. A small increase in concentration 

occurred downstream to site WF_1,748m. Aluminum, 

copper, manganese, and zinc concentrations decreased 

just downstream from the SWTF as treated water was 

released to Wightman Fork (table 7 in the Appendix at 

the back of report). Near the end of the study area, 

concentrations increased primarily due to inflow 

from Cropsy Creek.

The pH of Wightman Fork was acidic 

along the entire study reach (fig. 9 and table 2). 

The highest pH values in the stream (pH 6.1) occurred 

just downstream from Pipeline Creek (WT_596m), 

although the effect of water contributed by Pipeline 

Creek (pH 7.5) was negated less than 200 meters 

downstream. The pH of Wightman Fork decreased 

to 4.5 by WF_817m and remained suppressed to 

the outfall from the SWTF (between WF_1,748m 

and WF_1,807m). Inflow pH values from tributaries 

and subsurface sampling pits along this reach were 

generally less than 4 standard units (table 6 in the 

Appendix at the back of report). Inputs of alkaline 

water from the treatment facility (pH 9.2) initially 

increased the pH in the stream slightly, but the pH 

remained near 4.6 along the entire secondary study 

reach (fig. 9).

0 500

0

10

20

110

30

40

50

60

70

80

90

100

DISCHARGE, IN LITERS PER SECOND

Error estimation

Estimated discharge (September 18, 1997)

Estimated discharge (September 19, 1997)

Estimated discharge from spot injection (September 19, 1997)

Instantaneous discharge measurement (September 19, 1997)

Inflow from unnamed tributary (WT_25m)

Inflow from Pipeline Creek (WT_596m)

Inflow from unnamed tributary(WT_845m)

Summitville Water Treatment Facility

(WT_1,774m and WT_1,777m)

1,500 2,000

DISTANCE FROM INJECTION SITE, IN METERS

1,000 2,500 3,000 Inflow from Cropsy Creek (WT_2,757m)

Figure 8. Discharge profiles in Wightman Fork during synoptic sampling, September 18 and 19, 1997.
TRACER-INJECTION AND SYNOPTIC-SAMPLING RESULTS 13

Table 2. Estimated discharge, pH, dissolved metal concentrations, and calculated dissolved metal loads in Wightman Fork at 

the Summitville Mine site, September 18 and 19, 1997

[Al, aluminum; Cu, copper; Fe, iron; Mn, manganese; Zn, zinc; ND, not detected; shaded area denotes secondary study reach] 

Site

identification

Estimated

discharge

(liters per

second)

pH

(standard

units)

Dissolved metal1 concentration 

(milligrams per liter)

Calculated dissolved metal load

(kilograms per day)

Al Cu Fe Mn Zn Al Cu Fe Mn Zn

WF_13m 4.55 4.2 4.93 0.06 0.60 1.64 0.85 1.94 0.02 0.24 0.64 0.33

WF_31m 8.68 4.9 4.01 .04 .38 1.09 .63 3.01 .03 .28 .82 .47

WF_54m 8.72 4.9 2.74 .03 .31 1.03 .56 2.07 .03 .24 .78 .42

WF_ 145m 8.90 4.9 2.75 .04 .39 1.03 .55 2.12 .03 .30 .79 .43

WF_ 265m 9.14 4.9 2.52 .03 .50 1.03 .56 1.99 .02 .39 .81 .44

WF_ 445m 9.54 4.8 2.53 .03 .58 1.05 .64 2.09 .03 .48 .86 .53

WF_ 592m 9.89 4.8 2.26 .03 .72 1.06 .57 1.93 .02 .62 .90 .49

WF_ 622m 19.4 6.1 .04 .01 .34 .58 .32 .06 .02 .56 .97 .54

WF_ 682m 19.5 6.1 .05 ND .41 .62 .35 .09 .02 .69 1.05 .59

WF_ 742m 19.6 5.9 .09 ND .37 .61 .34 .16 .02 .62 1.04 .59

WF_ 802m 19.8 5.4 .32 .03 .38 .70 .38 .55 .05 .64 1.21 .65

WF_ 817m 21.0 4.5 6.91 .25 .44 1.50 .81 12.5 .45 .79 2.72 1.47

WF_ 832m 22.3 4.4 20.10 .81 .64 3.11 1.57 38.7 1.56 1.23 5.99 3.03

WF_ 862m 25.4 4.4 32.19 1.60 1.56 4.61 2.45 70.8 3.51 3.44 10.1 5.38

WF_ 890m 25.5 4.3 30.11 1.46 1.65 4.27 2.25 66.5 3.22 3.64 9.42 4.98

WF_ 922m 25.7 4.2 30.15 1.47 1.95 4.58 2.41 66.9 3.25 4.33 10.2 5.34

WF_ 954m 25.8 4.2 31.84 1.49 1.84 4.55 2.37 71.1 3.33 4.11 10.2 5.30

WF_ 993m 26.0 4.3 31.65 1.50 1.66 4.56 2.37 71.1 3.38 3.74 10.2 5.32

WF_ 1,042m 26.2 4.3 31.10 1.56 1.79 4.62 2.53 70.4 3.53 4.06 10.5 5.74

WF_ 1,083m 26.4 4.2 32.34 1.65 1.94 4.69 2.60 73.8 3.75 4.43 10.7 5.93

WF_ 1,102m 26.5 4.2 30.89 1.66 1.98 4.66 2.53 70.7 3.81 4.54 10.7 5.80

WF_ 1,131m 26.6 4.2 30.64 1.70 1.98 4.64 2.51 70.5 3.92 4.55 10.7 5.77

WF_ 1,163m 26.8 4.2 35.65 2.27 1.96 5.18 2.86 82.5 5.26 4.53 12.0 6.62

WF_ 1,214m 27.1 4.2 37.04 2.47 1.98 5.36 2.86 86.4 5.77 4.63 12.5 6.68

WF_ 1,259m 27.2 4.1 31.92 2.45 1.79 4.99 2.43 75.1 5.77 4.20 11.7 5.73

WF_ 1,274m 27.3 4.2 32.67 2.34 1.79 5.07 2.74 77.1 5.51 4.23 12.0 6.46

WF_ 1,332m 29.2 4.2 31.76 2.36 1.72 5.00 2.62 80.2 5.95 4.33 12.6 6.61

WF_ 1,392m 29.5 4.2 34.10 2.25 1.63 4.92 2.68 86.9 5.74 4.16 12.5 6.83

WF_ 1,485m 29.9 4.2 34.49 2.26 1.62 5.09 2.86 89.1 5.83 4.19 13.2 7.39

WF_ 1,599m 30.4 4.1 34.30 2.37 1.45 5.09 2.69 90.2 6.24 3.82 13.4 7.07

WF_ 1,645m 30.6 4.1 34.80 2.36 1.40 5.02 2.69 92.2 6.26 3.71 13.3 7.13

WF_ 1,748m 31.2 4.2 33.40 2.55 1.48 5.65 3.10 89.9 6.86 3.99 15.2 8.34

WF_ 1,748m 36.4 4.3 23.74 1.82 1.09 4.12 2.07 74.7 5.73 3.42 13.0 6.50

WF_ 1,807m 64.4 4.6 11.82 1.74 1.62 2.46 0.98 65.8 9.71 8.99 13.7 5.45

WF_ 1,964m 64.5 4.7 9.27 1.51 1.51 2.42 0.93 51.7 8.42 8.43 13.5 5.21

WF_ 2,384m 64.7 4.6 9.46 1.67 1.55 2.62 1.03 52.9 9.33 8.69 14.6 5.76

WF_ 2,755m 64.9 4.6 10.87 2.26 2.18 4.31 1.17 60.9 12.7 12.2 24.2 6.57

WF_ 2,815m 90.1 4.6 14.58 2.24 2.91 5.12 1.44 113 17.5 22.7 39.9 11.2

1Sample water filtered through 0.1-micrometer plate filter.
14 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

METAL LOADS

Mass loading in Wightman Fork for 

dissolved aluminum, copper, iron, manganese, 

and zinc is discussed in the following sections and 

is graphically depicted in figures 10, 11, and 12. 

The load profiles incorporate estimations of error, 

as described previously, that include variation in 

chloride flux and analytical error. Loads in the 

primary reach were calculated using data collected 

on September 18, 1997; no metals data were 

collected along the secondary reach on that day. 

Loads in the secondary reach were calculated 

using data collected on September 19, 1997. As 

such, the two load profiles were not continuous 

along the entire study reach; however, metal loads 

at site WF_1,748m were calculated on both days 

and provide a semiquantitative comparison between 

the two reaches.

Data collected from inflow sites were used 

to help identify source areas along the two study 

reaches (table 7 in the Appendix at the back of report). 

In general, metal sources were not specifically identified, but were generalized as source areas within a 

stream reach. 

Primary Study Reach

Dissolved aluminum, copper, iron, manganese, and zinc loads were relatively low and generally remained stable from the injection point to 

site WF_802m (figs. 10–12 and table 2). Aluminum 

loads, however, decreased downstream from 

site WF_592m as near-neutral water (pH 7.5) from 

Pipeline Creek (WT_596m) entered Wightman 

Fork. Downstream from Pipeline Creek, the pH of 

the stream increased from 4.8 to 6.1 standard units 

(table 2), and aluminum precipitates were observed 

on the streambed. 

Metal loads increased substantially 

between sites WF_802m and WF_862m. This 

reach is north of the NWD and is downgradient 

from spring and seep inflows from the northern 

toe of the NWD (fig. 2). The area generally corresponds to a region of radial faults as described 

in Morrison Knudsen Corporation (1997). Three 

inflow sites were sampled along this 60-meter reach in 

an attempt to identify potential sources. The inflows 

consisted of seepage from a small ponded area situated 

above the stream (WT_807m), flow from an arroyo 

below the NWD (WT_829m), and flow from bogs 

Figure 9. pH profiles in Wightman Fork and inflow sites, September 18 and 19, 1997.

0 1,000 1,500 2,000 2,500 500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

2

10

3

4

5

6

7

8

9

pH (September 18, 1997)

pH (September 19, 1997)

pH of inflow site

WT_596m

WF_954m

WT_1,777m

WT_2,757m

pH, IN STANDARD UNITS
METAL LOADS 15

WT_596m

WF_954m

WT_1,777m

0

140

20

40

60

80

100

120

ALUMINUM LOAD, IN KILOGRAMS PER DAY

Error estimation

September 18, 1997

September 19, 1997

Error estimation

September 18, 1997

September 19, 1997

WT_2,757m

0 500 1,000 1,500 2,000 2,500 3,000

500 1,000 1,500 2,000 2,500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

0

20

2

4

6

8

10

12

14

16

18

COPPER LOAD, IN KILOGRAMS PER DAY

0

at the edge of the NWD (WT_845m). The three 

samples generally were similar in chemistry and 

exhibited high metal concentrations (table 7 in the 

Appendix at the back of report). Plumlee and others 

(1996) reported elevated concentrations of copper, 

iron, and zinc in several springs in this area that 

compared well with ground water chemistry from 

the underground workings area. Along this short 

stream reach, aluminum load increased nearly 

130-fold and copper load increased seventyfold. Iron, 

manganese, and zinc loads each increased between 5 

and 10 times. Metal loads from these inflows represented a substantial percentage of the dissolved 

aluminum (78 percent), copper (50 percent), iron 

Figure 10. Mass-load profiles for dissolved aluminum and copper in Wightman Fork, September 18 

and 19, 1997.
16 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

WT_596m

WF_954m

WT_1,777m

WT_2,757m

500 1,000 1,500 2,000 2,500 3,000

0

30

5

10

15

20

25

IRON LOAD, IN KILOGRAMS PER DAY

Error estimation

September 18, 1997

September 19, 1997

500 1,000 1,500 2,000 2,500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

0

50

10

20

30

40

MANGANESE LOAD, IN KILOGRAMS PER DAY

Error estimation

September 18, 1997

September 19, 1997

0

0

(70 percent), manganese (58 percent), and zinc 

(57 percent) load measured at the end of the primary 

reach (table 3). Overall, metal loading from just 

60 meters of the 1,748-meter reach was equivalent to 

50 percent or more of the dissolved aluminum, copper, 

iron, manganese, and zinc load at the downstream end 

of the primary study reach.

Metal loads, although somewhat variable, 

continued to increase downstream from site WF_862m 

to the end of the primary study reach but at a much 

lower rate; the increase in load was less than twofold 

for all the metals of concern. Diffuse subsurface inputs 

were the predominant source of metals to Wightman 

Fork downstream from site WF_862m.

Figure 11. Mass-load profiles for dissolved iron and manganese in Wightman Fork, September 18 

and 19, 1997.
METAL LOADS 17

Secondary Study Reach

Metal loads at site WF_1,748m represented 

the dissolved metal load in Wightman Fork upstream 

from the SWTF (the primary study reach). On 

September 19, 1997, the dissolved metal load at 

site WF_1,748m was equivalent to 66 percent of 

the aluminum load, 33 percent of the copper load, 

15 percent of the iron load, 33 percent of the manganese load, and 58 percent of the zinc load leaving the 

study area (table 4). It could be inferred from table 3 

then that the metal loads from the reach between 

WF_802m to WF_862 were equivalent to about 

51 percent of the aluminum load, 16 percent of the 

copper load, 10 percent of the iron load, 19 percent 

of the manganese load, and 33 percent of the zinc 

load leaving the secondary study area.

Metal loads in Wightman Fork showed 

some variability but generally continued to increase 

downstream along the secondary study reach 

(figs. 10–12 and table 2). Aluminum and zinc 

loads initially decreased between site WF_1,748m 

and site WF_1,807m. Effluent from the SWTF 

(WF_1,774m and WF_1,777m) and discharge 

from the Pump House Fault (WT_1,759m) were 

the primary sources of metal loading along this 

short reach (Environmental Chemical Corporation, 

1998). The SWTF was a substantial source of 

aluminum load, whereas the Pump House Fault 

was a substantial source for copper and iron load.3

Increased aluminum and zinc load was not observed 

farther downstream because alkaline water from the 

SWTF (pH 9.2) caused precipitation of the metals 

from the water column. Similar geochemical 

processes could have occurred for copper and iron 

but were likely masked by the loading from Pump 

House Fault. Manganese load along this short reach 

remained relatively stable. Overall, aluminum load 

decreased by 12 percent and zinc load decreased by 

16 percent along this 59-meter reach. Copper load, 

however, increased 69 percent and iron load 

increased 163 percent. These increases accounted 

for about 25 percent of the copper and iron load at 

the end of the study reach (table 4).

3Loads were estimated using daily mean discharge data for 

the treatment facility outfall (September 19) and an instantaneous 

discharge measurement of Pump House Fault (September 16) with 

USGS chemical data collected during the synoptic sampling on 

September 19, 1997.

WT_596m

WF_954m

WT_1,777m

0 1,000 1,500 2,000 2,500 500 3,000

DISTANCE FROM INJECTION SITE, IN METERS

0

14

2

4

6

8

10

12

ZINC LOAD, IN KILOGRAMS PER DAY

Error estimation

September 18, 1997

September 19, 1997

WT_2,757m

Figure 12. Mass-load profile for dissolved zinc in Wightman Fork, September 18 and 19, 1997.
18 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Table 4. Change in metal loads along selected stream reaches of Wightman Fork, and percentage of load from selected 

stream reaches when compared to loads at the end of the secondary study reach, September 19, 1997

Metal of 

concern

Change in metal load between 

selected Wightman Fork reach

(kilograms per day) Metal load 

at site WF_2,815m 

(kilograms per day)

Percentage of load at site WF_2,815m 

from selected stream reach

WF_13m to

WF_1,748m

WF_1,748m to 

WF_1,807m

WF_2,755m to

WF_2,815m

WF_13m to

WF_1,748m

WF_1,748m to 

WF_1,807m

WF_2,755m to

WF_2,815m

Aluminum 74.7 –8.90 52 113 66 losses

occur

46

Copper 5.73 3.98 4.8 17.5 33 23 27

Iron 3.42 5.57 10.5 22.7 15 25 46

Manganese 13.0 .7 15.7 39.9 33 2 39

Zinc 6.50 –1.05 4.6 11.2 58 losses

occur

41

In the secondary study reach, the largest 

increase in metal loading was as a result of inflow 

from Cropsy Creek (WT_2,757m) (figs. 10–12). 

Cropsy Creek delineates the southern and eastern 

boundary of the Summitville Mine and is in close 

proximity to the former Cropsy waste pile and the 

heap leach pad (fig. 2). Numerous acidic seeps (pH 2.2 

to 3.2) were identified in areas downgradient from the 

heap leach pad (Morrison Knudsen Corporation, 

1997); the pH of Cropsy Creek was 3.5 standard units. 

Just downstream from Cropsy Creek, aluminum and 

iron loads in Wightman Fork increased by about 

85 percent while manganese and zinc loads increased 

by more than 65 percent. Copper loads increased the 

least (38 percent). Aluminum, iron, manganese, and 

zinc loads from Cropsy Creek were equivalent to 

about 40 percent of the specific metal load at the end 

of the study reach (site WF_2,815m); copper load was 

equivalent to 27 percent of the load at site WF_2,815m 

(table 4). Copper, iron, and manganese loads from 

Cropsy Creek were nearly as large or larger than the 

load from the primary study reach; aluminum and zinc 

loads were about 20 percent smaller.

SUMMARY

In September 1997, a tracer-injection and 

synoptic water-quality sampling study was done 

to identify stream reaches where metal loading 

occurred. The two techniques provide a description 

of streamflow and metal concentrations in the 

stream. From that information, mass loading in the 

stream can be determined and source areas contributing the greatest loads can be identified. 

A continuous injection of chloride near the 

headwaters of Wightman Fork was done and mass 

loading of chloride to the stream was determined 

for two study reaches. Discharges at numerous 

sites in Wightman Fork were calculated and profiles 

were generated. During this study, 33 synoptic 

sites were sampled in the primary reach (0 to 

1,748 meters) and 6 synoptic sites were sampled 

in the secondary reach (1,748 to 2,815 meters). 

Synoptic sampling occurred along the primary 

study reach on September 18, 1997, and along the 

secondary study on September 19, 1997. Samples 

Table 3. Increase in metal loads along a selected stream reach of Wightman Fork, and percentage of load from selected 

stream reach when compared to loads at the end of the primary study reach, September 18, 1997

Metal of

concern

Increase in metal load between 

site WF_802m and site WF_862m

(kilograms per day)

Metal load at site WF_1,748m 

(kilograms per day)

Percentage of load at site WF_1,748m 

attributable to stream reach between

site WF_802m and site WF_862m

Aluminum 70.2 89.9 78

Copper 3.46 6.86 50

Iron 2.80 3.99 70

Manganese 8.89 15.2 58

Zinc 4.73 8.34 57
SUMMARY 19

were analyzed for dissolved aluminum, copper, 

iron, manganese, and zinc. Field measurements of 

pH were also made. Load profiles for the metals 

were determined by multiplying the discharge at 

each site by the concentration.

Metal loads along the primary study reach 

increased substantially. The largest increases 

occurred along a 60-meter reach bounded upstream 

by site WF_802m and downstream by site WF_862m. 

Metal loads for all five metals of concern increased 

anywhere from 5 to 130 times along this reach. The 

reach lies to the north of the North Waste Dump 

and is downgradient from spring and seep flow along 

the northern toe of the waste dump and generally 

corresponds to a region of radial faults. Metal loading 

from just 60 meters of the 1,748-meter reach was 

equivalent to 50 percent or more of the dissolved 

aluminum, copper, iron, manganese, and zinc load 

at the downstream end of the primary study reach 

(table 5). It also could be inferred that metal loads 

from this reach were equivalent to about 10 percent of 

the iron load, 16 percent of the copper load, 19 percent 

of the manganese load, 33 percent of the zinc load, and 

51 percent of the aluminum load leaving the secondary 

study area (table 5). 

Overall, sources along the primary study reach 

were equivalent to 15 percent of the iron, 33 percent of 

the copper and manganese, 58 percent of the zinc, and 

66 percent of the aluminum load leaving the mine site 

(table 5). In general, metal loads continued to increase 

downstream from the primary study reach; however, 

aluminum and zinc loads initially decreased downstream from the outfall from the Summitville Water 

Treatment Facility and discharge from the Pump 

House Fault. Alkaline effluent from the treatment 

facility caused aluminum and zinc to precipitate from 

the water column. Copper and iron loads increased 

substantially along this reach as discharge from the 

Pump House Fault entered Wightman Fork (table 5). 

The largest increases in metal loading to Wightman 

Fork occurred as a result of inflow from Cropsy Creek. 

Aluminum and iron loads in Wightman Fork increased 

by about 85 percent while manganese and zinc loads 

increased by more than 65 percent. Aluminum, iron, 

manganese, and zinc loads from Cropsy Creek were 

equivalent to about 40 percent of the specific metal 

load at the end of the study reach (table 5). Copper, 

iron, and manganese loads from Cropsy Creek were 

nearly as large or larger than the load from the primary 

study reach; aluminum and zinc loads were about 

20 percent smaller.

Table 5. Summary of dissolved metal loading for selected source areas along Wightman Fork to downstream end of primary 

and secondary study reaches, September 18 and 19, 1997

Source area delineated

by site identification number(s) Source of load

Equivalent percentage of dissolved metal 

at the downstream end of the study reach

Aluminum Iron Copper Manganese Zinc

Primary study reach (0 to 1,748 meters)

WF_802m to WF_862m Area corresponding to region of 

radial faults and downgradient 

from spring and seep inflows 

from the toe of the North Waste 

Dump

78 50 70 58 57

Secondary study reach (1,748 to 2,815 meters)

WF_0m to WF_1,748m All loads from primary study reach 66 33 15 33 58

WF_802m to WF_862m Area corresponding to region of 

radial faults and downgradient 

from spring and seep inflows 

from the toe of the North Waste 

Dump

51 16 10 19 33

WF_1,748m to WF_1,807m Pump House Fault and outfall from 

Summitville Water Treatment 

Facility

losses

occurred

23 25 2 losses

occurred

WF_2,755m to WF_2,815m Cropsy Creek 46 27 46 39 41
20 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

REFERENCES CITED

Bencala, K.E., McKnight, D.M., and Zellweger, G.W., 

1990, Characterization of transport in an acidic and 

metal-rich mountain stream based on a lithium tracer 

injection and simulations of transient storage: Water 

Resources Research, v. 26, no. 5, p. 989–1000.

Broshears, R.E., Bencala, K.E., Kimball, B.A., and 

McKnight, D.M., 1993, Tracer-dilution experiments 

and solute-transport simulations for a mountain stream, 

Saint Kevin Gulch, Colorado: U.S. Geological Survey 

Water-Resources Investigations Report 92–4081, 18 p.

Cleasby, T.E., Nimick, D.A., Kimball, B.A., 2000, Quantification of metal loads by tracer-injection and synopticsampling methods in Cataract Creek, Jefferson County, 

Montana, August 1997: U.S. Geological Survey WaterResources Investigations Report 00–4237, 39 p.

Crowfoot, R.M., Paillet, A.V., Ritz, G.F., Smith, M.E., 

Steger, R.D., and O’Neill, G.B., 1997, Water 

resources data for Colorado, water year 1996—v. 1, 

Missouri River Basin, Arkansas River Basin, and Rio 

Grande Basin: U.S. Geological Survey Water-Data 

Report CO–96–1, 512 p.

———1998,Water resources data for Colorado, water 

year 1997—v. 1, Missouri River Basin, Arkansas River 

Basin, and Rio Grande Basin: U.S. Geological Survey 

Water-Data Report CO–97–1, 513 p.

Environmental Chemical Corporation, 1998, Summitville 

Water Treatment Facility Draft Annual Report, 

1997: Contract number 1425–6–CS–40–18810, 

February 28, 1998.

Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, T.L., 

and Rickert, D.A., 1994, U.S. Geological Survey 

protocol for the collection and processing of surfacewater samples for the subsequent determination of 

inorganic constituents in filtered water: U.S. Geological Survey Open-File Report 94–539, 57 p.

Kimball, B.A., 1997, Use of tracer injections and synoptic 

sampling to measure loadings from acid mine 

drainage: U.S. Geological Survey Fact Sheet 245–96, 

4 p.

Kimball, B.A., Nimick, D.A., Gerner, L.J., and Runkel, 

R.L., 1999a, Quantification of metal loading in 

Fisher Creek by tracer injection and synoptic 

sampling, Park County, Montana, August 1997: 

U.S. Geological Survey Water-Resources Investigations Report 99–4119, 40 p.

Kimball, B.A., Runkel, R.L., Bencala, K.E., and WaltonDay, Katherine, 1999b, Use of tracer-injection and 

synoptic-sampling studies to quantify effects of metal 

loading from mine drainage, in Morganwalp, D.W., 

and Buxton, H.T., eds., U.S. Geological Survey Toxic 

Substances Hydrology Program, Proceedings of the 

Technical Meeting, Charleston, South Carolina, 

March 8–12, 1999—v. 1, Contamination from 

Hardrock Mining: U.S. Geological Survey WaterResources Investigations Report 99–4018A, 6 p.

Morrison Knudsen Corporation, 1997, Technical 

memorandum—Current understanding of South 

Mountain hydrogeology, Summitville Mine Superfund 

Site: ARCS Contract 68–W9–0025, Work Assignment 65–8LY3, Englewood, Colo.

Plumlee, G.S., Smith, K.S., Mosier, E.L., Ficklin, W.H., 

Montour, M., Briggs, P.H., and Meirer, A.L., 1995, 

Geochemical processes controlling acid-drainage 

generation and cyanide degradation at Summitville, 

in Posey, H.H., Pendleton, J.A., and Zyl, D.V., 

Proceedings—Summitville Forum 1995: Colorado 

Geological Survey, Special Publication 38, 375 p.

Plumlee, G.S., Smith, K.S., Montour, M.R., 1996, Compositions and metal loadings from several seeps at the 

Summitville Mine—Preliminary results of sampling in 

August 1995, and comparison to August 1994 results: 

U.S. Geological Survey Open-File Report 96–049, 6 p.

Zellweger, G.W., Bencala, K.E., McKnight, D.M., Hirsch, 

R.M., and Kimball, B.A., 1988, Practical aspects of 

tracer experiments in acidic, metal-enriched streams, 

in Mallard, G.E., ed., U.S. Geological Survey Toxic 

Substances Hydrology Program—Surface-Water 

Contamination: U.S. Geological Survey Open-File 

Report 87–764, p. 125–130.
APPENDIX
APPENDIX 23

Table 6. Site locations, specific conductance, and pH for inflows to Wightman Fork during tracer-injection and synopticsampling study, September 18 and 19, 1997

[m, meters; μS/cm; microsiemens per centimeter at 25 degrees Celsius; USEPA, U.S. Environmental Protection Agency; SWTF, Summitville Water Treatment Facility; shaded area denotes secondary study reach]

Site 

identifier

Distance

downstream from 

injection point

(m)

Field value

Inflow 

type Feature or description of inflow Specific

conductance

(μS/cm)

pH

(standard

units)

WT_11m 11 187 5.6 Pit Subsurface sampling pit near right bank

WT_25m 25 48 7.0 Tributary Previously sampled as site USEPA WF1

WT_29m 29 300 6.6 Pit Subsurface sampling pit near left bank

WT_43m 43 113 7.3 Tributary Small unnamed tributary along left bank

WT_70m 70 54 6.3 Pit Subsurface sampling pit near left bank

WT_79m 79 352 6.4 Pit Subsurface sampling pit near right bank

WT_163m 163 53 6.0 Tributary Small unnamed tributary along left bank

WT_258m 258 117 6.3 Pit Subsurface sampling pit near right bank

WT_473m 473 573 3.8 Diffuse Bog area along right bank

WT_596m 596 39 7.5 Tributary Tributary flow from Pipeline Creek along left bank

WT_598m 598 1,203 3.9 Tributary Small unnamed tributary along right bank

WT_807m 807 2,880 3.3 Pit Subsurface sampling pit adjacent to ponded area along right bank

WT_829m 829 2,330 3.3 Diffuse Seepage from arroyo cut along right bank downstream from bogs

WT_845m 845 2,400 2.8 Tributary Tributary flow along right bank downstream from bog area

WT_868m 868 1,189 3.3 Pit Subsurface sampling pit near right bank

WT_902m 902 1,887 3.2 Pit Subsurface sampling pit near right bank

WT_912m 912 2,000 3.4 Pit Subsurface sampling pit near right bank

WT_982m 982 805 3.3 Pit Subsurface sampling pit near right bank

WT_985m 985 930 3.0 Pit Subsurface sampling pit near right bank

WT_1,037m 1,037 829 3.0 Pit Subsurface sampling pit near right bank

WT_1,075m 1,075 925 3.0 Tributary Small unnamed tributary along right bank

WT_1,079m 1,079 760 3.0 Pit Subsurface sampling pit near right bank

WT_1,089m 1,089 653 3.0 Pit Subsurface sampling pit near right bank

WT_1,144m 1,144 355 5.7 Pit Subsurface sampling pit along left bank of dam impoundment

WT_1,156m 1,156 2,410 3.4 Tributary Small unnamed tributary along right bank downstream from dam

WT_1,267m 1,267 126 7.4 Tributary Unnamed tributary along left bank near historic building

WT_1,283m 1,283 523 4.4 Tributary Small unnamed tributary along right bank

WT_1,554m 1,554 1,455 3.2 Pit Subsurface sampling pit near right bank

WT_1,560m 1,560 990 5.0 Pit Subsurface sampling pit near right bank

WT_1,705m 1,705 2,170 4.5 Pit Subsurface sampling pit near right bank

WT_1,752m 1,752 2,410 3.7 Pit Subsurface sampling pit near right bank near pump house

WT_1,759m 1,759 1,570 3.6 Pipe Pump House Fault discharge pipe

WT_1,774m 1,774 2,790 9.2 Pipe SWTF discharge pipe

WT_1,777m 1,777 2,330 9.3 Pipe SWTF discharge pipe

WT_1,983m 1,983 68 7.3 Tributary Small unnamed tributary along left bank

WT_2,571m 2,571 2,330 3.9 Seepage Seepage below Summitville Dam Impoundment structure

WT_2,573m 2,573 2,300 4.0 Seepage Seepage below Summitville Dam Impoundment structure

WT_2,757m 2,757 814 3.5 Tributary Inflow from Cropsy Creek along right bank
24 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Table 7. Selected chemical data for synoptic samples collected from inflow sites to Wightman Fork during the tracer-injection 

and synoptic-sampling study on Wightman Fork, September 18 and 19, 1997

[Al, aluminum; Ca, calcium; Cd, cadmium; Co, cobalt, Cr, chromium; Cu, copper; Fe, iron; Li, lithium; Mg, magnesium; Mn, manganese; Ni, nickel; SiO2, 

silica; Na, sodium; Sr, strontium; Zn, zinc; ND, not detected]

Site 

identifier

Sample Element

(milligrams per liter)

Date Time Al Ca Cd Co Cr Cu Fe

WT_11m 09–18–97 1520 0.24 15.1 ND ND ND ND 12.7

WT_25m 09–18–97 1515 ND 5.6 ND ND ND ND .21

WT_29m 09–18–97 1505 ND 34.5 ND 0.01 0.08 ND 11.1

WT_43m 09–18–97 1500 ND 12.1 ND ND ND ND .15

WT_70m 09–18–97 1455 .08 5.7 ND ND ND ND 2.3

WT_79m 09–18–97 1455 .55 21.0 ND .01 .02 ND 89.5

WT_163m 09–18–97 1530 .14 6.0 ND ND ND ND .82

WT_258m 09–18–97 1430 .11 7.2 ND ND ND ND 23.7

WT_473m 09–18–97 1410 .32 61.5 ND ND .05 ND 8.9

WT_596m 09–18–97 1350 ND 4.5 ND ND ND ND .21

WT_598m 09–18–97 1400 .79 164 ND .01 .16 ND 16.7

WT_807m 09–18–97 1315 428 204 .13 1.1 .66 13.5 3.4

WT_829m 09–18–97 1305 303 121 .11 .96 .56 13.5 6.3

WT_845m 09–18–97 1255 260 85.1 .13 .90 .49 21.7 34.5

WT_868m 09–18–97 1250 117 46.3 .03 .39 .28 2.8 2.6

WT_902m 09–18–97 1225 231 70.6 ND .82 .69 1.4 8.4

WT_912m 09–18–97 1210 252 69.2 .10 .98 .76 11.6 1.6

WT_982m 09–18–97 1150 52.8 21.4 ND .08 .08 .42 17.0

WT_985m 09–18–97 1150 47.3 23.1 ND .88 .09 .55 26.4

WT_1,037m 09–18–97 1140 76.1 28.8 .02 .17 .29 6.3 14.5

WT_1,075m 09–18–97 1130 58.5 24.4 .02 .13 .25 4.8 7.1

WT_1,079m 09–18–97 1130 26.6 15.4 ND .06 .05 .85 4.2

WT_1,089m 09–18–97 1125 19.2 21.1 ND .04 .13 .33 2.9

WT_1,144m 09–18–97 1050 ND 35.9 ND ND ND .03 .19

WT_1,156m 09–18–97 1045 314 120 .14 1.1 .74 58.8 8.0

WT_1,267m 09–18–97 1015 ND 15.1 ND ND ND ND .41

WT_1,283m 09–18–97 1005 11.1 41.4 ND .04 .12 1.9 .34

WT_1,554m 09–18–97 0955 35.6 158 .03 .20 .17 11.9 4.9

WT_1,560m 09–18–97 0940 .83 142 ND .08 .01 .86 61.3

WT_1,705m 09–18–97 0925 13.6 357 .03 .24 .33 10.0 .18

WT_1,752m 09–19–97 1035 21.7 442 .03 .28 .56 11.3 1.0

WT_1,759m 09–19–97 1030 35.8 157 .03 .31 .17 75.5 106

WT_1,774m 09–19–97 1025 9.5 1,160 ND ND .02 .01 .02

WT_1,777m 09–19–97 1020 8.8 854 ND ND .02 ND ND

WT_1,983m 09–19–97 1000 .02 14.9 ND ND ND ND .12

WT_2,571m 09–19–97 0940 98.6 457 .08 1.0 .85 24.6 39.7

WT_2,573m 09–19–97 0935 37.1 351 .04 .56 .71 11.3 5.3

WT_2,757m 09–19–97 0925 20.0 86.3 ND .12 .15 2.0 11.3
APPENDIX 25

Table 7. Selected chemical data for synoptic samples collected from inflow sites to Wightman Fork during the tracer-injection 

study on Wightman Fork, September 18-19, 1997—Continued

[Al, aluminum; Ca, calcium; Cd, cadmium; Co, cobalt, Cr, chromium; Cu, copper; Fe, iron; Li, lithium; Mg, magnesium; Mn, manganese; Ni, nickel; SiO2, 

silica; Na, sodium; Sr, strontium; Zn, zinc; ND, not detected]

Site 

identifier

Sample Element

(milligrams per liter)

Date Time Li Mg Mn Ni SiO2 Na Sr Zn

WT_11m 09–18–97 1520 0.01 4.1 0.96 ND 19.8 3.3 0.26 0.16

WT_25m 09–18–97 1515 ND 1.5 .01 ND 19.1 2.4 .06 .01

WT_29m 09–18–97 1505 ND 9.0 5.5 ND 15.8 7.6 .62 ND

WT_43m 09–18–97 1500 ND 5.3 .04 ND 16.7 3.4 .17 ND

WT_70m 09–18–97 1455 ND 2.4 .46 ND 8.0 2.2 .07 ND

WT_79m 09–18–97 1455 ND 3.2 4.3 ND 19.0 3.0 .21 .04

WT_163m 09–18–97 1530 ND 1.2 .11 ND 23.0 3.3 .05 ND

WT_258m 09–18–97 1430 ND 1.6 .59 ND 21.8 3.8 .06 .03

WT_473m 09–18–97 1410 ND 17.1 1.2 ND 22.8 8.9 .65 .07

WT_596m 09–18–97 1350 ND 1.0 ND ND 26.5 2.0 .04 ND

WT_598m 09–18–97 1400 ND 51.9 5.0 .01 18.5 11.0 1.1 .17

WT_807m 09–18–97 1315 .06 73.0 37.9 1.3 61.8 8.0 .83 22.1

WT_829m 09–18–97 1305 .03 50.0 30.8 1.0 64.8 6.9 .57 17.7

WT_845m 09–18–97 1255 .04 40.7 28.4 1.0 79.6 7.6 .36 17.8

WT_868m 09–18–97 1250 .02 16.8 14.7 .40 67.7 6.2 .23 6.9

WT_902m 09–18–97 1225 .02 34.4 31.7 .69 54.7 6.2 .43 10.3

WT_912m 09–18–97 1210 .03 37.2 34.1 .89 55.5 6.1 .44 17.4

WT_982m 09–18–97 1150 ND 7.5 5.6 .13 67.5 8.7 .16 3.0

WT_985m 09–18–97 1150 ND 8.8 6.4 .12 57.4 8.0 .16 2.3

WT_1,037m 09–18–97 1140 .01 9.7 7.2 .22 65.0 7.3 .15 6.4

WT_1,075m 09–18–97 1130 .01 8.0 5.7 .18 61.5 7.0 .15 5.3

WT_1,079m 09–18–97 1130 ND 4.8 3.3 .09 56.9 7.0 .13 2.8

WT_1,089m 09–18–97 1125 ND 5.0 3.2 .07 55.1 6.7 .16 2.3

WT_1,144m 09–18–97 1050 .01 9.4 .26 ND 17.5 4.0 .41 .11

WT_1,156m 09–18–97 1045 .05 45.3 39.7 1.1 96.8 7.0 .55 18.9

WT_1,267m 09–18–97 1015 ND 5.1 .17 ND 20.3 3.2 .21 ND

WT_1,283m 09–18–97 1005 .06 12.7 3.2 .07 21.9 7.6 .45 1.4

WT_1,554m 09–18–97 0955 .48 20.5 9.7 .24 44.0 12.5 .61 7.8

WT_1,560m 09–18–97 0940 ND 9.4 2.5 .04 22.1 18.9 .37 1.9

WT_1,705m 09–18–97 0925 .01 42.1 12.2 .47 34.1 28.3 1.5 7.0

WT_1,752m 09–19–97 1035 .02 45.9 12.3 .44 40.5 34.0 1.5 7.7

WT_1,759m 09–19–97 1030 ND 31.1 9.1 .34 35.9 6.2 2.4 7.5

WT_1,774m 09–19–97 1025 ND 18.4 .87 ND .26 36.8 1.3 ND

WT_1,777m 09–19–97 1020 ND 17.3 .81 ND .25 36.4 1.2 ND

WT_1,983m 09–19–97 1000 ND 2.4 .03 ND 17.0 1.9 .10 ND

WT_2,571m 09–19–97 0940 .03 62.1 50.7 .73 63.2 32.6 1.9 12.3

WT_2,573m 09–19–97 0935 .01 75.1 39.6 .50 40.9 22.4 2.0 8.0

WT_2,757m 09–19–97 0925 ND 15.5 9.0 .12 22.5 5.7 .63 2.6
26 Determination of Instream Metal Loads Using Tracer-Injection and Synoptic-Sampling Techniques in Wightman Fork, 

Southwestern Colorado, September 1997

Table 8. Selected chemical data for synoptic samples collected from Wightman Fork during the tracer-injection and synopticsampling study on Wightman Fork, September 18 and 19, 1997

[Ca, calcium; Cd, cadmium; Co, cobalt, Cr, chromium; Mg, magnesium; Ni, nickel; SiO2, silica; Sr, strontium; ND, not detected]

Site 

identifier

Sample Element

(milligrams per liter)

Date Time Ca Cd Co Cr Mg Ni SiO2 Sr

WF_BG 09–18–97 1520 17.3 ND ND 0.07 5.4 0.01 19.9 0.12

WF_13m 09–18–97 1515 18.2 ND ND .02 5.3 .02 19.0 .12

WF_31m 09–18–97 1505 14.9 ND ND .05 4.1 .01 20.2 .11

WF_54m 09–18–97 1500 16.3 ND ND .01 4.3 .01 20.0 .11

WF_145m 09–18–97 1445 16.0 ND ND .01 4.4 .01 20.1 .11

WF_265m 09–18–97 1435 13.2 ND ND .01 4.4 .01 20.2 .12

WF_445m 09–18–97 1425 19.9 ND ND .01 4.5 .01 19.7 .13

WF_592m 09–18–97 1355 15.4 ND ND .01 4.8 .01 19.9 .13

WF_622m 09–18–97 1345 12.1 ND ND ND 3.1 ND 20.9 .09

WF_682m 09–18–97 1340 14.2 ND ND ND 3.5 ND 22.6 .10

WF_742m 09–18–97 1330 12.7 ND ND .03 3.3 ND 21.3 .10

WF_802m 09–18–97 1320 14.7 ND ND ND 3.8 ND 22.8 .11

WF_817m 09–18–97 1310 20.1 ND 0.02 .03 4.9 .02 21.9 .11

WF_832m 09–18–97 1305 26.3 ND .06 .06 7.0 .07 23.8 .13

WF_862m 09–18–97 1250 17.9 0.01 .10 .10 9.2 .11 27.8 .16

WF_890m 09–18–97 1245 21.9 .01 .09 .07 8.6 .11 26.8 .14

WF_922m 09–18–97 1205 23.0 .01 .10 .26 9.1 .11 27.6 .16

WF_954m 09–18–97 1200 24.2 .01 .09 .18 8.8 .11 27.4 .15

WF_993m 09–18–97 1145 23.6 .01 .10 .21 8.8 .11 27.3 .15

WF_1,042m 09–18–97 1135 21.7 .01 .10 .08 8.8 .11 27.3 .16

WF_1,083m 09–18–97 1130 20.8 .01 .10 .08 9.2 .12 28.3 .16

WF_1,102m 09–18–97 1100 19.7 .01 .11 .09 9.0 .13 28.1 .16

WF_1,131m 09–18–97 1055 19.0 .01 .11 .09 9.1 .13 28.3 .16

WF_1,163m 09–18–97 1045 22.4 .01 .11 .09 9.6 .13 29.1 .17

WF_1,214m 09–18–97 1040 28.4 .01 .12 .21 10.2 .13 30.8 .18

WF_1,259m 09–18–97 1017 25.2 .01 .10 .19 9.7 .12 28.5 .16

WF_1,274m 09–18–97 1010 22.6 .01 .11 .08 9.8 .13 28.8 .18

WF_1,332m 09–18–97 1000 21.3 .01 .11 .09 9.9 .13 28.7 .18

WF_1,392m 09–18–97 0955 27.3 .01 .11 .20 9.6 .12 28.4 .18

WF_1,485m 09–18–97 0950 24.7 .01 .11 .08 9.8 .12 28.3 .19

WF_1,599m 09–18–97 0935 28.1 .01 .10 .21 9.9 .12 28.7 .18

WF_1,645m 09–18–97 0930 28.4 .01 .10 .20 9.8 .11 28.5 .18

WF_1,748m 09–18–97 0920 18.0 .01 .12 .13 9.8 .13 29.7 .19

WF_1,748m 09–19–97 1040 141 ND .08 .10 11.2 .09 20.8 .43

WF_1,807m 09–19–97 1020 923 ND .04 .05 15.6 .04 13.2 .83

WF_1,964m 09–19–97 1005 484 ND .04 .14 13.1 .04 11.8 .89

WF_2,384m 09–19–97 0950 368 ND .04 .05 15.8 .04 12.7 .81

WF_2,755m 09–19–97 0930 409 ND .06 .07 16.3 .06 14.0 .86

WF_2,815m 09–19–97 0920 478 ND .07 .08 16.4 .07 15.5 .91