Water Quality and Aquatic Toxicity Data of


2002 Spring Thaw Conditions in the upper 
Contents 

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

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

Background......................................................................................................2 

Scope of Work...................................................................................................3 

Timing of Sampling.............................................................................................3 

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

Water Quality.........................................................................................4 

Sample Collection..........................................................................4 

Water-Chemistry Analyses................................................................5 

Aquatic Toxicity......................................................................................6 

Sample Collection...........................................................................6 

Aquatic Toxicity Analytical Methods....................................................6 

Water-Quality Results.........................................................................................6 

Aquatic Toxicity Results....................................................................................13 

Summary.......................................................................................................14 

Acknowledgements...........................................................................................15 

References.....................................................................................................16 

List of Figures 

Figure 1. Locality map of streamwater and toxicity sampling sites, upper Animas River, 

Colorado..............................................................................................4 

Figure 2. Discharge of Animas River at A-72 gage from early March to early May 2002.........5 

Figure 3. Discharge and turbidity over the sampling period March 27-30, 2002.....................7 

Figure 4. Concentration curves for calcium and strontium over the sampling 

period March 27-30, 2002..........................................................................7 

Figure 5. Concentration and load curves for sulfate over the sampling period March 27-30, 

2002....................................................................................................8 

Figure 6. Concentration and load curves for aluminum over the sampling period March 27-30, 

2002....................................................................................................8 

Figure 7. Concentration and load curves for silicon over the sampling period March 27-30, 

2002....................................................................................................9 

Figure 8. Concentration curves for total-recoverable iron, dissolved ferrous iron, dissolved 

ferrous plus ferric iron, with turbidity curve for comparison.................................10 

i 
Figure 9. Concentration and load curves for total-recoverable-iron over the sampling period 

March 27-30, 2002...................................................................................11 

Figure 10. Concentration and load curves for copper over the sampling period March 27-30, 

2002...................................................................................................11 

Figure 11. Concentration and load curves for lead over the sampling period March 27-30, 

2002...................................................................................................12 

Figure 12. Concentration and load curves for zinc over the sampling period March 27-30, 

2002...................................................................................................12 

Figure 13. Toxicity of stream water and dilutions from the Animas River at A-72 to 

amphipods............................................................................................13 

Figure 14. Toxicity of stream water and dilutions from the Animas River at A-72 to 

minnows...............................................................................................14 

List of Tables In Appendix 

Table A1. Field numbers, date, time, discharge, conductivity, pH, temperature, hardness, 

alkalinity, turbidity, ferrous iron, ferrous plus ferric iron, and fluorine, chlorine, and 

nitrate concentrations of water samples, Animas River water samples from A-72 gage, 

March 27-30, 2002...............................................................................A1 

Table A2. Field numbers, date, time, discharge, conductivity, pH, temperature, hardness, 

alkalinity, turbidity, ferrous iron, and fluorine, chlorine, and nitrate concentrations of 

water samples, Cement Creek, Mineral Creek, and upper Animas River, March 27-30, 

2002.................................................................................................A2 

Table A3. Date, time, discharge, and major and trace element data for unfiltered water at gage 

station A-72, Animas River below Silverton, March 27-30, 

2002..................................................................................................A3 

Table A4. Date, time, discharge, and major and trace element data for unfiltered water samples 

from Cement Creek, Mineral Creek, and upper Animas River, March 27-30, 

2002...................................................................................................A5 

Table A5. Quality control data for unfiltered water samples collected from Animas River, Cement 

Creek, and Mineral Creek near Silverton, Colorado, March 27-30, 2002..................A6 

Table A6. Survival of amphipods (Hyalella azteca) and fathead minnows (Pimephales promelas) 

in serial dilutions of stream water collected at gage station A-72, Animas River below 

Silverton, March 22-27 (Test 1), March 28-29 (Test 2), and May 1-6 (Test 3)...........A8 

ii 
Water Quality and Biological Toxicity Data of 2002 Spring Thaw

Conditions 

in the upper Animas River watershed, Silverton, Colorado 

Abstract 

This report presents hydrologic, water-quality, and biologic toxicity data collected during the 

annual spring thaw of 2002 in the upper Animas River watershed near Silverton, Colorado. The 

spring-thaw runoff is a concern because elevated concentrations of iron oxyhydroxides can 

contain sorbed trace metals that are potentially toxic to aquatic life. Water chemistry of streams 

draining the San Juan Mountains is affected by natural acid drainage and weathering of 

hydrothermal altered volcanic rocks and by more than a century of mining activities. The timing 

of the spring-thaw sampling effort was determined by reviewing historical climate and streamflow hydrographs and current weather conditions. Twenty-one water-quality samples were 

collected between 11:00 AM March 27, 2002 and 6:00 PM March 30, 2002 to characterize water 

chemistry at the A-72 gage on the upper Animas River below Silverton. Analyses of unfiltered 

water at the A-72 gage showed a relation between turbidity and total-recoverable iron 

concentrations, and showed diurnal patterns. Copper and lead concentrations were related to iron 

concentrations, indicating that these elements are probably sorbed to colloidal iron material. 

Calcium, strontium, and sulfate concentrations showed overall decreasing trends due to dilution, 

but the loads of those constituents increased over the sampling period. Nine water-quality 

samples were collected near the confluence of Mineral Creek with the Animas River, the 

confluence of Cement Creek with the Animas River, and on the upper Animas River above the 

confluence with Cement Creek (three samples at each site). A total of six bulk water-toxicity 

samples were collected before, during, and after the spring thaw from the Animas River at the A72 gage site. Toxicity tests conducted with the bulk water samples on amphipods did not show 

strong differences in toxicity among the three sampling periods; however, toxicity of river water 

to fathead minnows showed a decreasing trend during the course of the study. 

1 
Introduction 

The initial spring thaw or early rising limb of the snowmelt cycle typically produces highly 

turbid water. This is a particular concern in the highly mineralized upper Animas River watershed 

(fig. 1), containing hundreds of inactive prospects and mines, and characterized by naturally 

acidic drainage from a hydrothermally-altered volcanic complex. Water quality of alpine 

watersheds is highly seasonal and can change rapidly over short periods ranging from hours to 

days, particularly in response to warm weather that produces snowmelt runoff or to episodic 

storm runoff (Wirt and others, 2000; Leib and others, 1999; Sullivan and Drever, 2001). Local 

observers describe a spring thawing period when streams are highly turbid and turn orange-brown 

for a few days to a week during late March or early April. The color of the water is indicative of 

suspended iron hydroxides that form in acid drainage environments. Iron-oxide material can sorb 

and transport potentially toxic metals in the solid phase (Smith, 1999; Church and others, 1997; 

Horowitz and Elrick, 1987). Better understanding of this phenomenon is needed to determine 

whether this short-lived flush of iron hydroxides in the initial pulse of snowmelt may be a critical 

limiting factor for stream biota by mobilizing high concentrations of toxic metals (Besser and 

Leib, 1999; Besser and others, 2001). 

Snowmelt occurs when the snow pack becomes isothermal and melted water percolates 

through the snow pack. In a mineralized watershed such as the Animas River watershed, metalrich salts, iron hydroxides, and fine particulates stored during winter are mobilized from the soil 

zone. In addition, amorphous, colloidal iron-hydroxide material that formed in the water column 

and settled to the streambed or was deposited on stream banks during the low flow winter 

conditions can be mobilized by the increase in flow. The highest turbidity values are typically 

measured during these early stages of snowmelt and also in the runoff from large rainstorms 

(Wirt and others, 2000; Nimick and others, 2002). In the early stages of snowmelt, the turbidity is 

positively correlated with diurnal variations in stream-flow discharge. This is in contrast with the 

clear, relatively sediment-free discharge of winter base flow. Later in the cycle, the relatively 

pure snowmelt dominates the hydrograph and dilutes the diminishing fraction of more 

concentrated base flow that is derived from ground water. In this report we define the “spring 

thaw” phenomenon as the highly turbid, initial rising limb of the hydrograph resulting from the 

first pulse of snowmelt, which can last several days or longer. 

Few time-series data have previously been available to describe this brief transitional period 

between late winter base flow and the early snowmelt runoff—in part because of the forecasting 

and logistical difficulties of collecting such a dataset. Thus, we sought to characterize the 

variation in total metal concentrations and iron hydroxides, and the toxicity of the turbid water 

during this time period. This report presents water-quality and biologic toxicity data that were 

collected during the spring thaw of 2002 in the upper Animas River watershed near Silverton, 

Colorado. 

Background 

Since 1994, the USGS has been cooperating with the Animas River Stakeholders Group to 

characterize the effects of historical mines on the environment and to describe the occurrence of 

pre-mining concentrations of metals in the watershed. In 1997, the USGS started the Department 

of the Interior Abandoned Mine Lands (AML) Initiative in the upper Animas River watershed. 

The goal of the AML Initiative is to supply scientific information needed to develop cost-efficient 

remediation strategies for clean up of historical mine lands on Federal land in the western US. 

The spring thaw phenomenon was identified through analysis of data collected as part of AML, 

and an understanding of the event was identified as a data gap that needs to be addressed in the 

watershed. 

2 
Scope of Work 

The objectives of this study were 1) to collect and analyze a time-series set of water 

chemistry samples during the spring thaw, and 2) to conduct toxicity testing of amphipods and 

minnows with Animas River water. 

The study approach was to collect a time-series set of water samples at the A-72 gage of the 

Animas River below Silverton, Co. for chemical and toxicity analysis that are representative of 

spring thaw conditions. A total of thirty water-quality samples were collected from the Animas 

River and its tributaries near Silverton, Colorado during a 4-day period of high the turbidity that 

is characteristic of the spring thaw. The A-72 gage was selected as an integrator site for the 

Animas River watershed, owing to its position downstream from the confluence of the upper 

Animas River with Cement Creek and Mineral Creek (Fig. 1). Stream stage, discharge, water 

temperature, pH, specific conductance, and turbidity were measured at the continuous monitor 

probe at the Animas River below Silverton stream-flow gaging station (A-72; USGS gage site no. 

09359020, see fig. 1). The data were collected at 15-minute intervals, and transmitted to the 

internet via satellite telemetry. The data from the continuous probe were semi-quantitative, and 

were not regularly checked against known turbidity standards. However, the turbidity data were 

critical in determining the timing of the time-series water-quality and toxicity samples. The 

monitor probe and internet hookup were installed September 25, 2001, and removed July 23, 

2002. 

Timing of Sampling 

In addition to reviewing the data from the continuous monitor probe, we looked at historical 

climate data and stream-flow hydrographs. Prior to the field effort, historical stream-flow 

discharge at the A-72 gage and air temperature data from the South Mineral Creek weather 

station were compiled to estimate the timing of the spring thaw. Over the past 9 years, the 

average date of the beginning of the spring thaw has been April 3. This analysis helped to forecast 

the event and to explain the hydrologic processes contributing to it. Data from the continuous 

monitor probe were inspected daily throughout March to observe patterns in discharge and 

turbidity. 

The winter of 2001-2002 produced below 50 percent of normal snowfall resulting in an early 

and below-normal snowmelt runoff. Local weather for the Red Mountain Pass and Molas Pass 

weather stations was monitored for warming trends via internet. Between March 1 and March 27, 

2002, turbidity began to increase while discharge and specific conductance were relatively stable. 

Sampling began on March 27, soon after the 4-person sampling team arrived in Silverton, and 

ended three days later on March 30 when rising discharge made the river difficult to wade. The 

increased levels of turbidity continued until about April 5. 

The spring thaw is characterized by changes in discharge, turbidity, and specific conductance. 

Between March 27 and April 3, 2002, discharge had a strongly diurnal rising trend. The sampling 

timeframe brackets the transition between concentrated winter base flow and the higherdischarge, more dilute spring runoff. Figure 2 shows that the sampling period for this study did 

occur during the rising limb of the discharge curve, and that water-quality samples we collected 

are representative of spring-thaw conditions. 

3 
Figure 1. Map of the upper Animas River watershed, showing localities of mines and prospects 

(from USGS topographic maps), the localities of stream sampling and gaging sites, and index map 

showing location of the upper Animas River watershed in Colorado. 

Methods 

Water Quality 

Sample Collection 

A total of thirty water quality samples were collected from the Animas River and its 

tributaries near Silverton, Colorado during a 4-day period of high turbidity in which discharge 

increased at the A-72 gage from 70 to 140 cubic feet per second (ft3

/s) and turbidity ranged from 

approximately 40 to 160 normal turbidity units (NTU). Twenty-one of the water-quality samples 

were collected near the A-72 gage below Silverton (fig 1). These time-series samples were 

collected in a wide, relatively shallow reach just upstream from the gage. Samples were collected 

from noon on March 27 until 6:00 PM on March 30. Samples were generally collected at 6 AM, 

12 noon, 3 PM, 6 PM, 9 PM and 12 midnight. In addition, daily samples were collected near the 

gages on the three major upstream tributaries (fig 1)—Mineral Creek (M-34; gage site 

09359010), Cement Creek (C48; gage site 09358550), and the upper Animas River near Silverton 

(A68; gage site 09358000). 

4 
Figure 2. Graph showing discharge of Animas River from continuous water-quality monitor at A72 gage on Animas River below Silverton, Colorado, early March through early May 2002. The 

sampling period from March 27-30 is shown on the rising limb of the spring thaw. 

Each flow-weighted composite sample was collected with a DH-81 wading sampler (Shelton, 

1994) using the equal width integrated (EWI) approach described by Edwards and Glysson 

(1988). Field parameters including pH, water temperature, specific conductance, and dissolved 

oxygen were measured onsite from a container of composite water. The pH, temperature, and 

specific conductance values are in tables A1 and A2; dissolved oxygen readings were 

uncalibrated and incomplete, and are not presented. Samples were immediately transported to a 

refrigerator in a motel room in Silverton and acidified with ultrapure nitric acid usually within 12 

hours of collection. An aliquot of each sample was filtered using a 0.45-micron syringe-mounted 

filter and acidified with ultrapure hydrochloric acid for analysis of ferrous iron. A separate aliquot 

was filtered using a 0.45-micron syringe-mounted filter and acidified with ultrapure nitric acid for 

analysis of dissolved iron (Fe+2 and Fe+3). 

Four duplicate samples were collected— (1) at site A-72 (A-72 119, duplicate of A-72 118), 

(2) at the Mineral Creek site (MC-104, duplicate of MC-103), (3) at the Cement Creek site (CC103, duplicate of CC-102), and (4) at the upper Animas River site (UA-104, duplicate of UA103). We also collected four field blanks by processing de-ionized laboratory water in the motel 

room. 

Five suspended-sediment samples were collected at the A-72 site, one on March 27 (2 PM), 

one on March 28 (12 PM), two on March 29 (12 PM and 8:40 PM), and one on March 30 (6 PM). 

These samples were collected by filtering 6 liters of EWI stream water through a 142-millimeter 

diameter 0.7 micron filter in a pressurized stainless-steel filter apparatus. 

Water-Chemistry Analysis 

The unfiltered, acidified water samples were analyzed by ICP-AES (Briggs and Fey, 1996) 

and by inductively coupled plasma-mass spectroscopy (ICP-MS; Lamothe and others, 1999) for 

26 elements and sulfate. Data are in tables A3-A4. Samples labeled A-72 100-123 are from A-72 

gage site on the Animas River. Samples labeled CC 101-104 are from Cement Creek at Memorial 

Park in Silverton, about 0.2 mi below the C48 gage. Samples labeled MC 101-104 are from 

5 
Mineral Creek just above its confluence with the Animas River, at gage M34. Samples labeled 

UA 101-104 are from the Animas River above Cement Creek, at the A68 gage. Filtered, 

unacidified water samples were analyzed for the anions fluoride, chloride, and nitrate, by ion 

chromatography (d’Angelo and Ficklin, 1996). These data are in table A1-A2. Quality control 

data from the field duplicates, field blanks, and analytical standards are in table A5. 

Hydrochloric acid-filtered samples were measured for ferrous iron by spectrophotometer for 

only the samples from the A-72 site using the phenanthroline method (Hach Company, 1997). 

The ferrous iron results are in table A1. Nitric acid-preserved filtered samples were analyzed for 

both forms of iron by ICP-AES; these results are also in table A1. 

The suspended-sediment samples were analyzed by X-ray diffraction for mineralogy. 

Aquatic Toxicity 

Sample Collection 

A total of six water samples were collected at the A-72 site before, during, and after the 

spring thaw between March 22 and May 6, 2002 for toxicity testing. Unfiltered samples (10-20 L) 

were placed on ice and shipped on ice to the U.S. Geological Survey Columbia Environmental 

Research Center (CERC) in Missouri by overnight courier. Water samples were stored at 4 °C 

until used in toxicity tests. Two samples were used for each test: water for Test #1 was collected 

on March 22 and March 27; water for Test #2 was collected on March 28 and March 29; and 

water for Test #3 was conducted on May 1 and May 6. 

Toxicity Tests 

Seven-day toxicity tests were conducted with the amphipod, Hyalella azteca, and the fathead 

minnow, Pimephales promelas (U.S. Environmental Protection Agency, 1994). Amphipod tests 

were started with juveniles (7- to 14-days old) and minnow tests were started with newly-hatched 

larvae (less than 48-hr old). The primary toxicity endpoint for both species was survival. Both 

species were exposed to undiluted (100 percent) stream water and a series of three dilutions (50 

percent, 25 percent, and 12.5 percent). Stream water from the A-72 site was diluted with 

reconstituted water formulated to approximate the ionic composition of Animas River water 

during early snowmelt period (‘Animas Hard’ reconstituted water, or ARW; alkalinity = 9 mg/L 

as CaCO3, hardness 240 mg/L, sulfate 213 mg/L; Besser and others, 2001). Two sets of controls 

were used, one using ARW and another using CERC well water, diluted to equivalent hardness 

(diluted well water, DWW). Exposure water was replaced daily. 

Toxicity data were rank-transformed and analyzed by analysis of variance. Comparisons 

between A-72 stream water (and dilutions) and controls (ARW) were made by Dunnett’s onetailed test. Statements of statistical significance refer to p≤0.05. 

Water-Quality Results 

Discharge and turbidity at the A-72 gage site are related (fig 3) and both variables exhibit 

diurnal peaks. Daily maximum discharge and turbidity values occurred around 9 PM, and daily 

minimum values occurred around 9 am. Melting of snow during the daylight hours in the upper 

tributary basins provides increased water to the Animas River at A-72, with a lag time offsetting 

the integrated peak discharge. Over the duration of the sampling period, the difference between 

the low and high discharges also increased. On March 27, the flow ranged from 53 to 74 cubic 

feet per second (ft3

/s), a variation of 21 ft3/s, or 28 percent. On March 29, the discharge ranged 

from 78 to 130 ft3

/s, a variation of 52 ft3/s, or 40 percent. The diurnal rise in stream discharge is 

due to both an increase in stream velocity and cross-sectional area. This increase in channel size 

and water velocity (stream energy) results in a greater amount of suspended material, producing a 

corresponding increase in turbidity. 

6 
Figure 3. Graph showing the diurnal variations in and relation between discharge in ft3

/s and 

turbidity in NTU versus time over the sampling period March 27-30, 2002. Turbidity values are 

semi-quantitative and subject to revision. 

Some chemical constituents showed an increase in concentration with a diurnal response over 

the sampling period, some showed a decrease in concentration, also with a diurnal response, and 

some showed a diurnal response with small or no change in concentrations. Figure 4 shows the 

concentration curves of total calcium and strontium. The presence of these constituents in the 

water is the result of weathering of rock-forming minerals such as feldspars in the watershed. 

They show a noticeable decreasing concentration trend owing to dilution from the increased 

Figure 4. Graph showing total calcium and strontium concentrations for March 27-30, 2002 at the 

A-72 gage, Animas River below Silverton. The concentrations of both constituents decrease with 

time due to dilution by snowmelt, superposed by diurnal fluctuations. 

7 
snowmelt discharge. Calcium and strontium concentrations also exhibit minimum and maximum 

concentrations; the maximum concentration roughly corresponding to the minimum discharge 

values, and the minimum concentrations corresponding to maximum discharge values. Calcium is 

the dominant cation in these waters. 

Figure 5. Graph showing total sulfate concentration and load for March 27-30, 2002 at the A-72 

gage, Animas River below Silverton. Sulfate concentration shows a decreasing trend over time 

due to dilution by snowmelt, superposed by diurnal fluctuations. 

Sulfate, the dominant anion, whose concentration through time is shown in figure 5, also 

exhibits a decreasing trend with diurnal peaks. The general decrease in sulfate concentration is 

due to dilution by snowmelt. The sulfate load, however, that is the concentration multiplied by the 

discharge, experiences a generally increasing trend. 

Figure 6. Graph showing total aluminum concentration and load for March 27-30, 2002 at the A72 gage, Animas River below Silverton. Aluminum concentrations do not increase or decrease 

with time but may show a slight diurnal pattern. 

8 
The aluminum concentrations (fig 6) vary between 2,500 and 3,500 parts per billion (ppb). 

There appears to be some diurnal fluctuation in aluminum concentrations, but there is no clear 

trend. 

Silicon concentrations (fig 7) show little variation over the sampling period. There is no clear 

diurnal response; however the silicon load increases over the sampling period due to the sharp 

increase in discharge. 

Figure 7. Graph showing total silicon concentration and load for March 27-30, 2002 at the A-72 

gage, Animas River below Silverton. Silicon concentration shows little variation over time, with 

no obvious diurnal pattern. 

Iron concentrations in unfiltered samples (total-recoverable iron) show a strong diurnal 

response (fig. 8, upper line). On March 28 and 29 a maximum concentration occurred about 9 

PM. This maximum concentration was 2.5 times greater than the minimum concentrations, which 

occur at about 11 AM or noon. The maximum and minimum values relate strongly to both 

discharge and turbidity. The concentration curves for both dissolved iron and ferrous iron (filtered 

at 0.45 microns) are also shown on figure 9. The two curves match each other closely, indicating 

that the dissolved iron is present mostly as ferrous iron. The dissolved and ferrous iron 

concentrations range from 10 to 60 percent of the total-recoverable iron concentrations. The 

lowest ratios occur when the total-recoverable iron concentrations peak. Since this is when the 

turbidity and discharge are greatest, it is evident that at peak discharges, the majority of iron is 

transported as suspended material, and this material is responsible for the turbidity. X-ray 

diffraction of the suspended sediment material revealed that it is mostly amorphous colloidal 

material, with some detrital quartz and possibly some feldspar. 

The response of dissolved (presumably mostly ferrous) iron concentrations in 0.45-micronfiltered water shows an inverse response to turbidity and the total-iron concentrations (fig. 8). The 

ferrous iron concentrations peak at around noon and reach minimum values at around 9 PM. 

There are several mechanisms that may account for this relation. One explanation involves 

photoreduction of iron, and turbidity. More photoreduction of ferric iron from colloidal material 

to dissolved ferrous iron would occur during peak daylight hours, and when water is clearer. The 

largest dissolved ferrous iron concentrations occur at around noon, just before the turbidity begins 

9 
Figure 8. Graph showing turbidity in NTU, total-recoverable iron concentrations, 0.45 micronfiltered ferrous iron, and .045 micron-filtered ferrous plus ferric iron for March 27-30, 2002 at the 

A-72 gage, Animas River below Silverton. Iron concentrations are positively related with 

discharge and turbidity. The dissolved iron concentrations are inversely related to the totalrecoverable-iron and turbidity trends. Ferrous iron concentrations and ferrous plus ferric iron 

concentrations nearly match, indicating that the dissolved iron is predominantly ferrous. The 

ferrous iron concentration highs occur near noon on each day, indicating that photoreduction of 

ferric iron may be taking place. Turbidity values are semi-quantitative and subject to revision. 

to rise (fig 8). The increase in turbidity would block sunlight from reaching the full depth of the 

water, reducing the amount of material exposed to photoreduction. Another explanation could be 

that increased discharge results in dilution of the dissolved iron. 

A third possibility is that the increased turbidity of samples collected during the peak 

discharges causes plugging of the 0.45- micron filters. If the dissolved iron is not truly dissolved, 

but present as material smaller than 0.45 microns, then plugging of the filter would prevent some 

of that material from being analyzed. However, the dissolved iron concentrations dip the same 

amount on the first day of the sampling period, when the turbidity and total-iron concentrations 

rise by only a small amount, suggesting that filter plugging is not the main factor. It is not clear 

which one or combination of factors is responsible for the relation between the dissolved iron and 

the total-recoverable iron. 

The overall concentration trend of dissolved iron did not increase over the 3-day sampling 

period. However, the total-recoverable-iron load increased considerably, from 640 kg/day to over 

4,000 kg/day (Fig. 9). Much of the iron load is present as colloidal material (Fig. 8); some of this 

colloidal iron fills in the interstitial space in the streambed, introducing other metals (see below) 

into that environment. These introduced metals can affect benthic invertebrate life (Fey and 

others, 2002). 

Both copper (fig 10) and lead concentrations (fig 11) increase in response to diurnal changes 

in discharge. These concentrations are also related to total-recoverable iron concentrations. 

Copper and lead derive from the weathering of sulfide minerals in the watershed. Between stream 

pH of 5 to 6, these metals are largely sorbed to iron oxyhydroxides (Smith, 1999) that settle along 

stream banks and on streambed bottoms during low flow. The increases in copper and lead 

concentrations in unfiltered samples through time result from the increase in discharge, which 

mobilizes the bed sediment. 

10 
Figure 9. Graph showing total-recoverable iron concentration and load for March 27-30, 2002 at 

the A-72 gage, Animas River below Silverton. 

Zinc concentrations are greater than either copper or lead concentrations (fig. 12). Zinc 

concentrations also exhibit a slight increasing trend, but do not show a distinct diurnal relation 

with iron or turbidity. Zinc is less likely to sorb to iron colloids under the ambient pH conditions 

(Smith, 1999) and so zinc concentrations do not correlate total-iron concentrations. Zinc is likely 

to be present as a dissolved species and not as a sorbed constituent. 

Figure 10. Graph showing total copper concentration and load for March 27-30, 2002 at the A-72 

gage, Animas River below Silverton. Copper concentrations are positively related with iron 

concentrations, suggesting copper is sorbed to solid-phase iron material. 

11 
Figure 11. Graph showing total lead concentration and load for March 27-30, 2002 at the A-72 

gage, Animas River below Silverton. Lead concentrations are positively related with iron 

concentrations, suggesting lead is sorbed to solid-phase iron material. 

Figure 12 also shows the zinc load increased during the sampling period. Despite a relatively 

constant concentration, the load increases as a result of the increasing discharge. Copper and lead 

loads increased more than zinc loads, because these concentrations also increased. 

Figure 12. Graph showing total zinc concentration and load for March 27-30, 2002 at the A-72 gage, 

Animas River below Silverton. Variations in zinc are unrelated to those for turbidity or iron. At the pH of 

the sampled waters, zinc is not sorbed to colloidal iron material. Zinc load increase over time following the 

trend of diurnal discharge. 

Tables A2 and A4 present data for water samples collected from the Cement Creek, Mineral 

Creek, and upper Animas River sites. Concentration difference between these sites and the 

Animas A-72 site demonstrate the geochemical differences between the subbasins. Aluminum 

12 
concentrations were greatest in Cement Creek, probably a result of the weathering of clay-rich 

altered rock in that basin. The sulfate content of Cement Creek was greater than the other sites, 

probably due to exposures of acid-sulfate altered rock. Calcium, strontium, and iron 

concentrations were also greatest in Cement Creek, and the pH is the lowest of the three major 

tributaries. Mineral Creek had the highest concentrations of copper. The upper Animas River 

generally had the lowest concentrations of most other constituents, except manganese. 

Manganese concentrations and pH were highest in the upper Animas River. 

Aquatic Toxicity Results 

Amphipod toxicity tests did not show strong differences in toxicity among the three sampling 

periods (Figure 13). Undiluted water from the A-72 site caused nearly complete mortality of 

amphipods in all three tests. The high survival of amphipods in the 50 percent dilution in Test #1 

indicated that toxicity of stream water at the A-72 site during the pre-snowmelt period was less 

than that observed during the corresponding period in April 1999 (Besser and others, 2001). 

Toxicity of stream water to amphipods increased somewhat during Test #2, as evidenced by 

significant toxic effects in the 50 percent dilution. Results of Test #3 were difficult to interpret, 

because deterioration of the reconstituted ARW water (about one month after preparation) led to 

poor survival in all dilutions. However, undiluted stream water remained highly toxic during this 

test, with amphipod survival similar to that in tests conducted during late summer conditions in 

1998 (Besser and others, 2001). 

Figure 13. Graph showing toxicity of stream water from the Animas River (station A-72) and 

dilutions to amphipods (Hyalella azteca). Controls are DWW (diluted well water) and ARW 

(reconstituted Animas water). Asterisks indicate significant differences between stream water and 

controls (ARW). Undiluted (100%) Animas sample water from all three sampling periods 

was toxic to Hyalella azteca. Toxicity observed in the 50% dilutions indicated greater toxicity in 

Test #2 than in test #1. Test #3 results were affected by deteriorated control water (see text). 

13 
Toxicity of stream water to fathead minnows showed a decreasing trend during the course of 

the study (fig. 14). Toxicity was greatest during pre-snowmelt conditions (Test #1), when both 

undiluted stream water and the 50 percent dilution caused 100 percent mortality. Toxicity 

decreased slightly during early snowmelt (Test #2), as indicated by partial survival in the 50 

percent dilution, and no toxicity was observed during the late snowmelt period (Test #3). For 

minnows, toxicity in the first two tests was similar to that observed in a previous pre-snowmelt 

period (April 1999), and the absence of toxicity during the late-snowmelt period was similar to 

results of previous tests with this species during late-summer low flow of August 1998 (Besser 

and others, 2001). 

Figure 14. Graph showing toxicity of stream water from the Animas River (station A-72) and 

dilutions to fathead minnows (Pemephales promelas). Asterisks indicate significant differences 

between stream water and controls (ARW). Stream water was highly toxic to minnows in test #1, 

but toxicity decreased slightly in test #2, and was completely eliminated in test #3. 

Summary 

Water quality, suspended sediment, and toxicity-testing water samples were collected from 

the Animas River near the A-72 gage station below Silverton, Colorado from March 27 to March 

30, 2002. Discharge and specific conductance data from early March to early April 2002 and 

turbidity data from early March to early May 2002 characterizing the early spring thaw of the 

snow pack in the upper Animas River basin. Discharge was positively related to turbidity, and 

inversely related to specific conductance. Discharge, turbidity, and specific conductance showed 

strong diurnal patterns. 

Analyses of unfiltered water samples at A-72 revealed that total-recoverable iron 

concentrations were positively related to turbidity and strongly diurnal. X-ray diffraction analysis 

indicated that suspended sediment is mostly amorphous, colloidal material. Total-recoverable iron 

concentrations increased three-fold and the total-recoverable iron load increased by nearly seven14 
fold over the sampling period. Copper and lead concentrations were related to total-recoverable 

iron concentrations, indicating these elements are likely sorbed to colloidal iron material. Zinc 

concentrations showed neither a strong diurnal pattern nor an increasing or decreasing 

concentration trend over time. Calcium, strontium, and sulfate concentrations showed diurnal and 

overall decreasing trends. Aluminum and silicon concentrations showed relatively little variation 

with some possible diurnal effects. The increase in discharge over the sampling period resulted in 

increasing loads for all constituents, including those whose concentrations decreased over time. 

Dissolved ferrous iron was inversely related to total-recoverable iron and turbidity. Maximum 

ferrous-iron concentrations occurred near noon each day, indicating photo reduction of ferric iron 

may be responsible. Alternative explanations for this occurrence include diurnal dilution and 

filter plugging. 

Analyses of water samples from Cement Creek, Mineral Creek, and the upper Animas River 

demonstrated the difference in water chemistry between tributaries. Cement Creek had the 

greatest aluminum, sulfate, calcium, strontium, and iron concentrations and the lowest pH. 

Mineral Creek had the greatest copper concentrations, and the upper Animas River had the 

greatest manganese concentrations and highest pH. 

Toxicity tests conducted with water from A-72 collected before, during, and after the spring 

thaw indicated little difference in toxicity between the pre-snowmelt and early snow-melt periods. 

Toxicity tests conducted using fathead minnows showed a decrease in toxicity over time, with no 

toxicity observed during the late snowmelt period. Results of the toxicity tests provide little 

evidence to support the hypothesis that turbid water from the early snowmelt or spring thaw 

period has greater toxicity than water from typical low-flow winter conditions. 

Acknowledgements 

Andy Gleason of the Silverton Avalanche group provided local weather information and 

snowmelt prediction. Robert McDougal provided valuable assistance during sample collection. 

We thank Monique Adams for the ICP-MS analyses, and Rhonda Driscoll for the X-ray 

diffraction analyses. Douglas Hardesty, Chris Ivey and James Kunz conducted the toxicity tests. 

We acknowledge Suzanne Paschke for her helpful review of this manuscript. 

Funding for this study was partly provided by the Albuquerque District Office of the Army 

Corps of Engineers under contract number W81G6920955792. The USGS Central Region, Office 

of the Director, provided funding to purchase a continuous monitor probe at the Animas River 

below Silverton (A-72) stream-flow gaging station. 

15 
References 

Besser, J.M., and Leib, K.J., 1999, Modeling frequency of occurrence of toxic concentrations of 

zinc and copper in the upper Animas River, in U.S. Geological Survey Toxic Substance 

Hydrology Program, Proceedings of the technical meeting, Charleston, South Carolina, 

March 8-12, 1999--Volume 1-Contamination from Hardrock mining: U.S. Geological Survey 

Water Resources Investigations Report 99-4018A, p. 75-81. 

Besser, J.M., Allert, A.L., Hardesty, D., Ingersoll, C.G., May, T.W., and Wang, N., 2001, 

Evaluation of metal toxicity in streams of the upper Animas River watershed, Colorado: 

Biological Science Report, BSR-2001-01. U.S. Geological Survey, Columbia Environmental 

Research Center, Columbia, Missouri. 

Briggs, P.H., and Fey, D.L, 1996. Twenty-four elements in natural and acid mine waters by 

inductively coupled plasma-atomic emission spectrometry, in Arbogast, B.F., ed., Analytical 

methods manual for the Mineral Resources Program, U.S. Geological Survey Open-File 

Report 96-525, p. 95-101. 

d’Angelo, W.M., and Ficklin, W.H., 1996, Fluoride, chloride, nitrate, and sulfate in aqueous 

solution by chemically suppressed ion chromatography, in Arbogast, B.F., ed., Analytical 

methods manual for the Mineral Resources Program, U.S. Geological Survey Open-File 

Report 96-525, p. 63-67. 

Edwards, T.K., and Glysson, G.D., 1988, Field methods for measurement of fluvial sediment: 

U.S. Geological Survey Open-File Report 86-531, 118 p. 

Fey, D.L., Church, S.E., Unruh, D.M. and Bove, D.J., 2002, Water and Sediment Study of the 

Snake River Watershed, Colorado, Oct 9-12, 2001: U.S. Geological Survey Open-File Report 

02-330, 41 p. 

Hach Company, 1997, DR/2010 Spectrophotometer Procedures Manual: p. 327-330. 

Horowitz, A.J., and Elrick, K.A., 1987, The relation of stream sediment surface area, grain size, 

and composition to trace-element chemistry: Applied Geochemistry, Vol. 2, p. 437-451. 

Lamothe, P.J., Meier, A.L., and Wilson, S.A., 1999, The determination of forty four elements in 

aqueous samples by Inductively Coupled Plasma - Mass Spectrometry, U.S. Geological 

Survey Open File Report 99-151, 14 p. 

Leib, K.J., Wright, W.G., and Mast, M.A., 1999, Using flood-analysis techniques to estimate 

dissolved- zinc concentrations: Tailings and Mine Waste ‘99: Netherlands, A.A. Balkema 

Publications, p. 633- 638. 

Shelton, L.R., 1994, Field guide for collection and processing stream-water samples for the 

National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 94-

455, 42 p. 

Smith, K.S., 1999, Metal sorption on mineral surfaces: an overview with examples relating to 

mineral deposits: in Plumlee and Logsdon, editors, Reviews in economic geology, volume 6a, 

The environmental geochemistry of mineral deposits, p 161-182. 

16 
References 

Continued 

Sullivan, A.B., and Drever, J.I., 2001, Spatiotemporal variability in stream chemistry in a highelevation catchment affected by mine drainage: Journal of Hydrology, v. 252, p. 237-250. 

USEPA, 1994, Short-term methods for estimating the chronic toxicity of effluents and receiving 

water to freshwater organisms (Third edition): EPA-600-4-91-002. 

Wirt, L., Leib, K. J., and Mast, M. A., 2000, Chemical-constituent loads during thunderstorm 

runoff in a high-altitude alpine stream affected by acid drainage: ICARD 2000; Proceedings 

from the Fifth International Conference on Acid Rock Drainage, Vol. II, p. 1391-1401. 

17 
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Appendix 1. Date, time, discharge and field parameters for unfiltered samples,ferrous iron and ferrous plus ferric iron for filtered samples, and anion concentrations for filtered waters USGS gage station A-72 (site number 09359020) near Silverton, Colorado, March 27-30, 2002U.S. Geological Survey Open-File Report 02-0488 by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright 

specific Fe2+ plus 

Sample No. date time discharge conductance pH Temp Hardness Alkalinity Fe2+ Fe3+ 

CFS uS/cm deg C mg/L CaCO3 mg/L CaCO3 mg/L mg/L 

A72-100 3/22/02 0900 57 662 4.88 3.4 A72-101 3/27/02 1100 54 638 5.50 4.3 4.90 4.00 A72-102 3/27/02 1400 63 615 5.50 6.9 1.20 1.00 2.42 A72-103 3/27/02 1615 69 628 5.12 6.1 0.97 0.80 2.03 A72-104 3/27/02 1800 73 612 5.17 4.1 1.56 A72-105 3/27/02 2100 74 599 5.36 2.7 0.12 0.10 1.54 0.43 A72-106 3/28/02 0010 69 589 5.50 1.8 0.24 0.20 1.90 1.20 A72-107 3/28/02 0900 62 606 5.70 1.4 2.92 2.40 2.55 2.40 A72-108 3/28/02 1200 63 599 5.57 6.0 0.12 0.10 2.54 2.30 A72-109 3/28/02 1500 76 627 4.88 8.6 2.20 1.80 2.21 2.00 A72-110 3/28/02 1800 95 553 5.43 3.6 1.49 1.40 1.55 1.40 A72-111 3/28/02 2100 95 548 5.23 2.2 2.44 2.00 1.54 1.60 A72-112 3/29/02 0005 89 544 5.26 1.2 0.98 0.80 2.06 1.80 A72-113 3/29/02 0610 80 568 5.67 0.1 3.90 3.20 2.43 2.20 A72-114 3/29/02 0900 80 611 5.70 1.4 2.93 2.40 2.57 2.40 A72-115 3/29/02 1200 81 564 5.05 7.4 2.59 2.50 A72-116 3/29/02 1502 97 583 5.15 7.2 1.46 1.20 2.32 2.20 A72-117 3/29/02 1805 127 521 5.38 3.6 1.70 1.40 1.66 1.40 A72-118 3/29/02 2040 127 495 5.30 2.3 1.83 1.50 1.61 1.50 A72-119 3/29/02 2040 127 495 5.30 2.3 1.46 1.20 1.47 1.40 A72-120 3/30/02 0610 103 523 5.69 0.2 4.15 3.40 2.33 2.10 A72-121 3/30/02 1800 145 482 5.43 4.4 0.49 0.40 1.90 1.70 A72-122 5/1/02 1340 246 283 6.35 8.3 12.80 10.5 0.35 A72-123 5/6/02 1440 270 255 6.02 11.5 14.02 11.5 

A1 
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--------

Appendix 2. Date, time, field parameters for unfiltered samples, ferrous iron for filtered samples,and anion concentrations for filtered waters at Cement Creek in Memorial Park (CC-48; 09358550),Mineral Creek above Animas River (M-34; 09359010), and upper Animas River (A-68 09358000), March 27-30, 2002U.S. Geological Survey Open-File Report 02-0488 by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright 

specific 

Sample No. date time conductance pH T Hardness Alkalinity Fe2+ Cl- F- NO3-

uS/cm deg C mg/L CaCO3 mg/L CaCO3 mg/L mg/L mg/L mg/L 

CC-101 3/27/02 1535 1032 3.88 8.8 0 0 0.2 1.5 0.6 

CC-102 3/28/02 1430 961 3.80 9.8 0 0 0.3 1.9 <.08 CC-103 3/28/02 1435 961 3.80 9.8 0 0 0.5 1.5 <.08 CC-104 3/29/02 1740 787 3.79 6.3 0 0 1.6 0.7 1.1 

MC-101 3/27/02 1500 648 5.12 6.1 0.61 1.50 1.5 1.2 0.6 

MC-102 3/28/02 1415 635 4.25 5.2 0 0 2.2 0.7 0.6 

MC-103 3/29/02 1410 560 4.45 5.5 0 0 3.0 0.8 <.2 

MC-104 3/29/02 1805 525 4.71 3.1 0.24 0.20 2.5 0.6 0.6 

UA-101 3/27/02 1530 416 6.92 3.2 33 27 1.2 0.7 0.5 

UA-102 3/28/02 1430 426 6.11 4.9 34 30 1.4 0.6 0.7 

UA-103 3/29/02 1720 378 6.59 2.2 32 26 1.4 0.6 1.6 

UA-104 3/29/02 1715 415 6.06 2.2 31 25 1.4 0.8 1.3 

A2 
Appendix 3. Date, time, discharge, and major and trace element data for unfiltered water 

at USGS gage station A-72 (09359020) near Silverton, Colorado, March 27-30, 2002 U.S. Geological Survey Open-File Report 02-0488 by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright Field No. date time discharge Al ug/L As ug/L Ba ug/L Be ug/L Ca mg/L Cd ug/L Co ug/L Cu ug/L Fe mg/L K mg/L La ug/L 

CFS ICP-MS ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS 

A72-101 3/27/02 1100 54 2760 2.0 21.0 0.3 119 2.12 7.57 27.7 4.5 1.1 2.11 A72-102 3/27/02 1400 63 2730 2.0 21.6 0.3 112 2.01 8.02 26.8 4.4 1.1 2.22 A72-103 3/27/02 1615 69 3240 2.0 21.2 0.4 111 2.11 8.28 28.8 5.4 1.1 2.53 A72-104 3/27/02 1800 73 3210 2.0 23.3 0.3 108 2.15 7.79 34.5 5.2 1.2 2.14 A72-105 3/27/02 2100 74 3490 3.0 22.9 0.4 106 2.16 9.00 34.5 5.8 1.2 2.45 A72-106 3/28/02 0010 69 3060 2.0 22.3 0.3 105 2.27 7.89 39.3 5.0 1.1 2.38 A72-107 3/28/02 0900 62 2940 2.0 21.6 0.3 108 2.43 7.59 39.7 4.6 1.1 2.12 A72-108 3/28/02 1200 63 2820 2.0 22.1 0.3 108 2.24 8.41 43.0 4.4 1.0 2.18 A72-109 3/28/02 1500 76 3210 2.0 22.4 0.3 109 2.22 8.41 41.7 5.0 1.1 2.28 A72-110 3/28/02 1800 95 3020 3.0 23.1 0.4 96 2.37 6.97 48.1 6.2 1.1 2.42 A72-111 3/28/02 2100 95 3250 4.1 25.2 0.4 96 2.46 7.55 54.9 13 1.3 2.48 A72-112 3/29/02 0005 89 2910 3.0 23.1 0.4 94 2.62 7.30 55.2 6.9 1.2 2.38 A72-113 3/29/02 0610 80 2660 2.0 22.3 0.3 101 2.57 6.91 44.7 5.1 1.1 2.07 A72-114 3/29/02 0900 80 2650 3.0 22.6 0.3 100 2.54 6.87 43.7 5.0 1.1 2.03 A72-115 3/29/02 1200 81 2640 2.0 22.0 0.3 102 2.65 7.15 46.5 5.1 1.0 2.15 A72-116 3/29/02 1502 97 2950 2.0 22.3 0.3 99 2.52 7.82 47.2 5.8 1.1 2.18 A72-117 3/29/02 1805 127 3520 5.4 29.4 0.4 90 2.64 7.42 61.7 14 1.1 2.79 A72-118 3/29/02 2040 127 3250 4.8 29.1 0.4 83 2.76 7.40 71.1 13 1.2 2.79 A72-119 3/29/02 2040 127 3220 4.1 28.6 0.4 81 2.80 7.23 70.5 12 1.2 2.59 A72-120 3/30/02 0610 103 2540 2.0 23.4 0.3 91 3.42 6.79 56.9 5.6 0.98 2.02 A72-121 3/30/02 1800 145 3190 4.0 29.8 0.4 80 3.28 7.00 61.3 12 1.0 2.52 

A3 
Appendix 3. Date, time, discharge, and major and trace element data for unfiltered water 

at USGS gage station A-72 (09359020) near Silverton, Colorado, March 27-30, 2002 continued U.S. Geological Survey Open-File Report 02-0488 by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright Field No. date time discharge Mo ug/L Na mg/L Ni ug/L P mg/L Pb ug/L Sc ug/L Si mg/L SO4 mg/L Sr ug/L Ti ug/L V 

CFS ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS IC

A72-101 3/27/02 1100 54 0.79 4.0 7.3 0.02 8.1 1.6 8.0 259 1090 3.6 A72-102 3/27/02 1400 63 0.55 4.0 7.3 0.02 8.2 1.5 8.2 258 1070 4.0 A72-103 3/27/02 1615 69 0.62 3.9 7.4 0.04 11.7 1.6 8.3 260 1060 5.0 A72-104 3/27/02 1800 73 0.68 4.0 7.0 0.04 14.2 1.6 8.5 305 1090 5.3 A72-105 3/27/02 2100 74 0.60 3.9 7.2 0.05 14.1 1.6 8.7 301 1060 4.6 A72-106 3/28/02 0010 69 0.69 3.5 7.1 0.03 16.4 1.5 8.2 240 984 4.2 A72-107 3/28/02 0900 62 0.96 4.2 7.3 0.02 11.7 1.6 8.5 262 1060 3.6 A72-108 3/28/02 1200 63 0.84 3.6 69 0.02 11.6 1.4 8.1 249 1050 3.4 A72-109 3/28/02 1500 76 0.51 4.0 7.5 0.03 13.4 1.5 8.3 302 1060 4.6 A72-110 3/28/02 1800 95 0.96 3.8 6.8 0.05 20.2 1.6 7.6 228 934 4.7 A72-111 3/28/02 2100 95 0.57 3.5 7.8 0.09 24.0 1.5 7.9 229 915 4.7 A72-112 3/29/02 0005 89 0.53 3.8 6.4 0.04 21.8 1.4 7.3 217 893 3.9 A72-113 3/29/02 0610 80 0.58 3.7 6.8 0.03 14.2 1.6 7.5 235 936 4.0 A72-114 3/29/02 0900 80 2.47 3.8 6.2 0.03 13.4 1.4 8.1 239 964 3.3 A72-115 3/29/02 1200 81 0.68 3.8 6.7 0.03 14.2 1.5 7.4 224 938 3.9 A72-116 3/29/02 1502 97 0.55 3.7 6.9 0.04 15.8 1.4 7.8 277 981 4.3 A72-117 3/29/02 1805 127 0.87 3.6 6.7 0.10 35.1 1.7 7.4 209 861 7.6 A72-118 3/29/02 2040 127 1.05 3.5 6.4 0.10 39.2 1.6 7.1 193 802 6.5 A72-119 3/29/02 2040 127 0.67 3.4 6.2 0.10 34.4 1.6 7.1 195 807 5.6 A72-120 3/30/02 0610 103 0.96 3.3 6.1 0.03 17.4 1.4 7.4 215 866 3.6 A72-121 3/30/02 1800 145 0.75 3.0 5.7 0.10 31.3 1.5 7.2 186 762 5.4 

A4 
Appendix 4. Date, time, and major and trace element data for unfiltered water

at Cement Creek in Memorial Park (CC-48; 09358550),Mineral Creek above Animas River (M-34; 09359010), and upper Animas River (A-68 09358000), March 27-30, 2002U.S. Geological Survey Open-File Report 02-0488 by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright Field No. date time Al ug/L As ug/L Ba ug/L Be ug/L Ca mg/L Cd ug/L Co ug/L Cu ug/L Fe mg/L K mg/L La ug/L L

ICP-MS ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS IC

CC-101 3/27/02 1535 6310 8.9 15.5 0.7 190 2.13 15.9 33.8 11 2.0 2.30 CC-102 3/28/02 1430 5290 5.3 15.1 0.6 150 2.24 14.2 39.6 8.3 1.7 2.13 CC-103 3/28/02 1435 6060 5.7 15.7 0.6 180 2.34 16.7 43.5 9.9 1.8 2.17 CC-104 3/29/02 1740 7360 12.6 48.4 0.7 120 3.03 19.0 74.3 40 1.5 4.62 

MC-101 3/27/02 1500 5410 1.0 23.3 0.4 110 2.01 13.6 52.8 6.8 0.84 5.59 MC-102 3/28/02 1415 4770 2.0 23.8 0.4 100 2.44 11.3 238 7.4 0.80 4.88 MC-103 3/29/02 1410 4360 2.0 25.1 0.3 91 2.61 9.59 92 8.9 0.78 3.82 MC-104 3/29/02 1805 5220 4.2 26.1 0.4 83 2.65 9.06 115 14 0.76 4.19 

UA-101 3/27/02 1530 280 <1 26.1 0.1 74 2.51 1.44 10.2 0.73 0.83 0.72 UA-102 3/28/02 1430 364 <1 25.7 0.1 74 2.76 2.00 12.3 1.1 0.93 0.88 UA-103 3/29/02 1720 366 <1 23.2 0.2 65 2.73 1.72 18.7 1.1 1.2 1.21 UA-104 3/29/02 1715 386 <1 23.5 0.2 66 2.68 1.76 17.6 1.2 1.2 1.24 

Field No. date time Mo ug/L Na mg/L Ni ug/L P mg/L Pb ug/L Sc ug/L Si mg/L SO4 mg/L Sr ug/L Ti ug/L V ug/L Y 

ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS IC

CC-101 3/27/02 1535 1.67 4.5 15.2 0.09 17.9 3.0 15.5 471 2030 10.1 4.0 CC-102 3/28/02 1430 0.53 3.4 12.8 0.06 17.9 2.3 14.0 418 1850 6.7 2.9 CC-103 3/28/02 1435 < 0.2 4.1 14.2 0.07 19.0 2.4 13.9 521 1990 8.1 3.4 CC-104 3/29/02 1740 0.35 3.1 13.8 0.40 49.5 3.2 12.6 378 1350 12.5 12.2 

MC-101 3/27/02 1500 0.35 5.1 7.2 0.02 14.1 1.6 9.1 278 983 3.8 1.0 MC-102 3/28/02 1415 0.6 4.8 6.7 0.03 24.1 1.6 8.2 240 907 3.8 1.0 MC-103 3/29/02 1410 0.59 4.3 5.9 0.04 28.9 1.5 8.2 226 836 3.7 1.1 MC-104 3/29/02 1805 1.84 4.6 5.9 0.06 44.8 1.7 7.9 206 782 5.2 1.8 

UA-101 3/27/02 1530 2.08 2.8 3.3 0.01 6.6 0.7 4.1 149 695 3.8 0.2 UA-102 3/28/02 1430 3.36 2.8 3.8 0.01 7.6 0.8 4.3 190 744 3.9 0.2 UA-103 3/29/02 1720 1.42 2.7 3.4 0.04 11.1 0.8 3.6 128 607 3.1 0.2 UA-104 3/29/02 1715 1.46 2.5 3.1 0.04 10.6 0.7 3.8 134 617 2.8 0.2 

A5 
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Appendix 5. Quality control data for unfiltered water samples collected from Animas River, Cement Creek, and Mineral Creek near Silverton, Colorado, March 27-30, 2002 U.S. Geological Survey Open-File Report 02-0488 

by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright 

Sample No. Al ug/L As ug/L Ba ug/L Be ug/L Ca mg/L Cd ug/L Co ug/L Cu ug/L Fe mg/L K mg/L La ug/L L

ICP-MS ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-AES ICP-MS ICP-MS IC

A72-901 field blank <0.1 <1 <0.1 <0.05 < 1 <0.02 <0.02 <0.5 < 0.05 <0.03 < 0.01 A72-902 field blank 0.43 <1 <0.1 <0.05 < 1 <0.02 <0.02 <0.5 < 0.05 <0.03 < 0.01 A72-903 field blank 0.15 <1 <0.1 <0.05 < 1 <0.02 <0.02 <0.5 < 0.05 <0.03 < 0.01 A72-904 field blank 0.35 <1 0.32 <0.05 < 1 <0.02 <0.02 <0.5 < 0.05 <0.03 < 0.01 WRD-131 water standard 135 55.3 491 13.5 30 6.48 26.3 22.2 0.094 2.8 0.02 WRD-131, certified 132 57 507 12 30.6 6.1 25 20 0.091 2.39 WRD-135 water standard 9.84 9.6 65.3 59.9 10 49.5 44.2 64.3 0.24 1.0 0.03 

WRD-135, certified 10.5 10 67.8 59 10.4 50.5 40 62 0.228 0.96 

WRD-137 water standard 29.2 <1 62 5.5 37 6.93 0.19 1.8 0.071 1.2 0.04 

WRD-137, certified 30.5 0.6 65 5.2 38.1 6.8 0.4 1.9 0.071 1.19 

WRD-161 water standard 53.8 22.5 68.9 12 7.4 16.5 12.1 21 0.080 1.2 0.13 

WRD-161, certified 32 26 70 13 7.2 17 13 22 0.062 1.26 

A72-118 3250 4.8 29.1 0.4 83 2.76 7.40 71.1 13 1.2 2.79 A72-119 field duplicate 3220 4.1 28.6 0.4 81 2.80 7.23 70.5 12 1.2 2.59 MC-102 4770 2.0 23.8 0.4 100 2.44 11.3 238 7.4 0.80 4.88 MC-103 field duplicate 4360 2.0 25.1 0.3 91 2.61 9.59 92 8.9 0.78 3.82 UA-103 366 <1 23.2 0.2 65 2.73 1.72 18.7 1.1 1.2 1.21 UA-104 field duplicate 386 <1 23.5 0.2 66 2.68 1.76 17.6 1.2 1.2 1.24 

A6 
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Appendix 5. Quality control data for unfiltered water samples collected from Animas River, Cement Creek, and Mineral Creek near Silverton, Colorado, March 27-30, 2002 contined U.S. Geological Survey Open-File Report 02-0488 

by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright 

Sample No. Mo ug/L Na mg/L Ni ug/L P mg/L Pb ug/L Sc ug/L Si mg/L SO4 mg/L Sr ug/L Ti ug/L 

ICP-MS ICP-AES ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS ICP-MS 

A72-901 field blank < 0.2 < 1 <0.1 < 0.01 <0.05 < 0.1 < 0.2 < 2 < 0.5 < 0.1 A72-902 field blank 0.59 < 1 <0.1 < 0.01 <0.05 < 0.1 < 0.2 < 2 < 0.5 < 0.1 A72-903 field blank < 0.2 < 1 <0.1 < 0.01 <0.05 < 0.1 < 0.2 < 2 < 0.5 < 0.1 A72-904 field blank < 0.2 < 1 <0.1 < 0.01 <0.05 < 0.1 < 0.2 < 2 < 0.5 < 0.1 WRD-131 water standard 113 21.0 62.6 < 0.01 16.3 0.8 3.3 2.0 291 0.2 WRD-131, certified 112 21.4 56 18 295 WRD-135 water standard 55.4 30.0 69.1 0.03 94.9 0.3 2.1 5.0 48.1 0.4 

WRD-135, certified 63 30.8 65.6 103 2.0 46 

WRD-137 water standard 7.12 20.0 16 0.06 5.9 0.7 3.3 40 220 0.7 

WRD-137, certified 8.9 22.0 15 6.3 3.24 230 

WRD-161 water standard 15.1 37 28 < 0.01 15.8 1.3 7.1 4 52 1.8 WRD-161, certified 19 43 29 16 6.9 54 A72-118 1.05 3.5 6.4 0.10 39.2 1.6 7.1 193 802 6.5 A72-119 field duplicate 0.67 3.4 6.2 0.10 34.4 1.6 7.1 195 807 5.6 MC-102 0.6 4.8 6.7 0.03 24.1 1.6 8.2 240 907 3.8 MC-103 field duplicate 0.59 4.3 5.9 0.04 28.9 1.5 8.2 226 836 3.7 UA-103 1.42 2.7 3.4 0.04 11.1 0.8 3.6 128 607 3.1 UA-104 field duplicate 1.46 2.5 3.1 0.04 10.6 0.7 3.8 134 617 2.8 

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Appendix 6. Survival of amphipods (Hyalella azteca ) and fathead minnows (Pimephales 

promelas ) in serial dilutions of stream water collected at gage station A-72, Animas River 

below Silverton, March 22-27 (Test 1), March 28-29 (Test 2), and May 1-6 (Test 3). DWW=diluted 

well water; ARW= Animas reconstituted water (control). 

U.S. Geological Survey Open-File Report 02-0488 

by D.L. Fey, L. Wirt, J.M. Besser, and W.G. Wright 

Treatment Replicate Amphipod survival (of 10) Minnow survival (of 10) 

Test 1 Test 2 Test 3 Test 1 Test 2 Test 3 

DWW 1 10 10 10 10 10 10 

DWW 2 10 10 10 10 9 9 

DWW 3 10 10 10 9 9 10 

DWW 4 10 10 10 10 10 9 

DWW 5 9 10 9 

DWW 6 10 10 10 

ARW 1 8 8 3 10 10 10 

ARW 2 8 8 2 10 8 9 

ARW 3 8 6 3 10 8 9 

ARW 4 9 8 3 9 10 8 

ARW 5 8 7 3 

ARW 6 7 6 2 

A-72 12.5% 1 8 6 3 10 9 4 

A-72 12.5% 2 9 9 2 10 10 2 

A-72 12.5% 3 9 9 2 10 9 10 

A-72 12.5% 4 8 6 3 9 10 10 

A-72 12.5% 5 10 6 3 

A-72 12.5% 6 9 9 3 

A-72 25% 1 10 9 5 10 10 10 

A-72 25% 2 9 8 5 9 10 8 

A-72 25% 3 9 4 7 10 10 9 

A-72 25% 4 8 7 4 8 10 9 

A-72 25% 5 9 8 2 

A-72 25% 6 10 7 4 

A-72 50% 1 7 4 3 0 3 10 

A-72 50% 2 9 7 4 0 4 9 

A-72 50% 3 10 4 0 0 4 8 

A-72 50% 4 10 1 8 0 4 10 

A-72 50% 5 8 2 5 

A-72 50% 6 9 4 4 

A-72 100% 1 0 0 0 0 0 10 

A-72 100% 2 0 0 0 0 0 10 

A-72 100% 3 0 0 1 0 0 9 

A-72 100% 4 0 0 0 0 0 10 

A-72 100% 5 0 0 0 

A-72 100% 6 0 0 0 

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