U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 

Characterization of Water Quality in 

Selected Tributaries of the Alamosa 

River, Southwestern Colorado, Including 

Comparisons to Instream Water-Quality 

Standards and Toxicological Reference 

Values, 1995–97

By Roderick F. Ortiz and Sheryl A. Ferguson

Denver, Colorado

2001

00 –4170

Prepared in cooperation with the

U.S. ENVIRONMENTAL PROTECTION AGENCY
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 the Study Area ..................................................................................................................................... 3

Methods Of Investigation....................................................................................................................................................... 3

Data-Collection Methods............................................................................................................................................. 3

Data-Analysis Methods ............................................................................................................................................... 4

Estimation of Hardness for Selected Sites......................................................................................................... 4

Lack of Dissolved-Metal Data for Selected Sites.............................................................................................. 5

Use of Censored Data ........................................................................................................................................ 5

Comparison of Aggregated Data to Instream Standards ................................................................................... 5

Comparison of Instantaneous Data to Instream Standards and Toxicological Reference Values...................... 5

Summary Statistics for Selected Tributary Sites.................................................................................................................... 6

Comparisons to Instream Standards and Toxicological Reference Values............................................................................ 6

pH Comparisons .......................................................................................................................................................... 11

Copper Comparisons ................................................................................................................................................... 12

Iron Comparisons......................................................................................................................................................... 13

Zinc Comparisons........................................................................................................................................................ 14

Summary................................................................................................................................................................................ 15

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

Appendix................................................................................................................................................................................ 17

FIGURES

1. Map showing location of study area and water-quality sampling sites in the Alamosa River Basin, 1995–97........ 2

TABLES

1. Summary of water-quality data collected at tributary sites to the Alamosa River, southwestern Colorado, 

1995–97 ................................................................................................................................................................... 4

2. Summary statistics for selected tributary sites in the Alamosa River Basin, 1995–97 ........................................... 7

3. Classifications and numeric standards for tributaries to the Alamosa River........................................................... 11

4. Toxicological reference values for aquatic biota in the Alamosa River Basin........................................................ 12

5. Percent instantaneous exceedance of instream pH standards and toxicological reference values for selected

tributary sites in the Alamosa River Basin, 1995–97 .............................................................................................. 12

6. Percent instantaneous exceedance of instream copper standards and toxicological reference values for selected

tributary sites in the Alamosa River Basin, 1995–97 .............................................................................................. 13

7. Percent instantaneous exceedance of instream iron standards and toxicological reference values for selected 

tributary sites in the Alamosa River Basin, 1995–97 .............................................................................................. 14

8. Percent instantaneous exceedance of instream zinc standards and toxicological reference values for selected

tributary sites in the Alamosa River Basin, 1995–97 .............................................................................................. 15

9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the 

Alamosa River, 1995–97 ......................................................................................................................................... 19
IV CONTENTS

CONVERSION FACTORS, ABBREVIATIONS, AND ACRONYMS

Multiply By To obtain

mile 1.609 kilometer

feet 0.3047 meter

inch 2.54 centimeter

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.

Abbreviations used in this report:

mg/L milligram per liter

μg/L microgram per liter

μS/cm microsiemens per centimeter at 25 degrees Celsius

s.u. standard units

Acronyms used in this report:

USEPA U.S. Environmental Protection Agency

CDPHE Colorado Department of Public Health and Environment

USGS U.S. Geological Survey

TRV Toxicological reference value

TVS Table value standard

COC Constituent of concern

MLE Maximum likelihood estimation

ERA Ecological risk assessment
Abstract 1

Characterization of Water Quality in Selected 

Tributaries of the Alamosa River, Southwestern 

Colorado, Including Comparisons to Instream 

Water-Quality Standards and Toxicological 

Reference Values, 1995–97

By Roderick F. Ortiz and Sheryl A. Ferguson

Abstract

A comprehensive water-quality sampling 

network was implemented by the U.S. Geological 

Survey from 1995 through 1997 at 12 tributary 

sites to the Alamosa River. The network was 

designed to address data gaps identified in the 

initial ecological risk assessment of the 

Summitville Superfund site. Tributaries draining 

hydrothermally altered areas had higher median 

values for nearly all measured properties and 

constituents than tributaries draining unaltered 

areas. Colorado instream standards for pH, 

copper, iron, and zinc were in attainment at most 

tributary sites. Instream standards for pH and 

chronic aquatic-life standards for iron were not 

attained in Jasper Creek. Toxicological reference 

values were most often exceeded at Iron Creek, 

Alum Creek, Bitter Creek, Wightman Fork, and 

Burnt Creek. These tributaries all drain hydrothermally altered areas. 

INTRODUCTION

The upper Alamosa River Basin is a heavily 

mineralized area in the San Juan Mountains of southwestern Colorado (fig. 1). Metal contamination of 

streams has occurred for decades from the 

Summitville Mine site, from other smaller mines, and 

from natural metal-enriched acidic drainage in the 

basin (Walton-Day and others, 1995). Mining activities have occurred intermittently in the Summitville 

area since the late 1800’s. Large-scale open-pit mining 

began at the Summitville Mine site in the mid-1980’s 

and continued until the mine site was abandoned in 

late 1992 (Plumlee and Edelmann, 1995). As a result, 

the State of Colorado requested the U.S. Environmental Protection Agency (USEPA) to assume sitemaintenance responsibilities under the emergency 

response provisions of Superfund. Since 1992, the site 

has undergone substantial waste-pile consolidation, 

runoff rerouting, water treatment, and reclamation. In 

1998, the Colorado Department of Public Health and 

Environment (CDPHE) assumed shared site responsibility of the Summitville site with the USEPA 

(Plumlee and Edelmann, 1995).

In 1995, the initial ecological risk assessment of 

the Summitville Superfund site identified multiple 

data gaps in the available data for the site (MorrisonKnudsen Corp., 1995). The data gaps included, but 

were not restricted to, the characterization of background water-quality conditions in the basin, characterization of other stressors, such as storms, on the 

river, and characterization of exposure levels to 

aquatic and terrestrial biota. As a result, the U.S. 

Geological Survey (USGS) developed a comprehensive sampling analysis plan to help address some of 

the data gaps (Edelmann and Ortiz, U.S. Geological 

Survey, written commun., 1995 and 1997). Between 

1995 and 1997, data collection included the operation 

of several instantaneous streamflow stations and 

water-quality monitors, and periodic water-quality 

sampling at several sites in the Alamosa River and 

Wightman Fork, including numerous tributaries to the 
2 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons to 

Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Figure 1. Location of study area and water-quality sampling sites in the Alamosa River Basin, 1995–97.
METHODS OF INVESTIGATION 3

Alamosa River. These collected data were used to 

address the data gaps. Information in this report will 

be incorporated in the draft Tier II Summitville 

Ecological Risk Assessment (Camp Dresser and 

McKee Inc., 1999) to help address background waterquality conditions in the basin and exposure risk to 

aquatic biota.

Purpose and Scope

The purpose of this report is to characterize the 

water quality of selected tributaries to the Alamosa 

River. The available data are summarized to provide a 

general overview of the water quality at 12 tributary 

sites. The data also are compared to Colorado instream 

water-quality standards for pH, copper, iron, and zinc. 

In addition, the data are compared to toxicological 

reference values (TRVs) to determine if aquatic life is 

at risk from acute or chronic exposure to low-pH water 

or elevated concentrations of copper, iron, or zinc.

Description of the Study Area

The upper Alamosa River Basin is located in 

southwest Colorado (fig. 1). Elevations in the study 

area range from 8,400 feet to nearly 13,000 feet above 

sea level. Annual precipitation ranges from approximately 12 inches at the lower elevations to as much as 

40 inches at the top of the highest peaks (Miller and 

McHugh, 1994). Most of the precipitation is in the 

form of snowfall. 

The study area extends from the headwaters of 

the Alamosa River to just above Terrace Reservoir and 

has a drainage area of approximately 110 square miles 

(Stogner, 1996). Several areas in the basin are hydrothermally altered and contain sulfide minerals and 

precious metals. Runoff from mined areas and undisturbed altered areas can adversely affect the water 

quality in the basin.

Low-pH water with high concentrations of trace 

metals from the Summitville Mine site adversely 

affects Wightman Fork and the Alamosa River downstream from the confluence with Wightman Fork 

(Walton-Day and others, 1995). The Alamosa River 

also receives drainage from several tributaries draining 

the Stunner and the Jasper hydrothermally altered 

areas (fig. 1). Many other small tributaries flow into 

the Alamosa River along the 14-mile reach from the 

confluence of Wightman Fork to Terrace Reservoir. 

Most of these tributaries do not drain hydrothermally 

altered areas.

METHODS OF INVESTIGATION

Water-quality data were collected at selected 

tributary sites by the USGS from 1995 through 

1997 (table 9, in the Appendix at the back of report). 

The samples were collected as described in the sample 

analysis plan for the study (Edelmann and Ortiz, 

U.S. Geological Survey, written commun., 1995 and 

1997). Additional data collected by the USGS in 

October 1998 and June 1999 were used to support 

data-analysis approaches (Kirk Nordstrom, U.S. 

Geological Survey, written commun., 1998). These 

data were collected in conjunction with geochemical 

modeling efforts in the Alamosa River Basin. A 

description of the various approaches and uses of the 

data follows.

Data-Collection Methods

Water-quality samples were collected from 

12 tributaries to the Alamosa River from April 1995 

through October 1997. The tributaries (in downstream 

order) were Iron Creek, Alum Creek, Bitter Creek, 

Wightman Fork, Jasper Creek, Burnt Creek, Spring 

Creek, Fern Creek, Castleman Gulch, Silver Creek, 

Lieutenant Creek, and Ranger Creek (fig. 1). The level 

of sampling included various sampling frequencies 

and different constituent lists for many of the tributaries (table 1). Sites sampled at a frequency of seven 

to nine times per year were accessed throughout the 

year and represented all flow regimes in the basin; 

these sites drain hydrothermally altered areas and will 

be referred to as “Group 1 sites” (table 1). Sites 

sampled at a frequency of four to five times per year 

generally were sampled between May and September 

and drained unaltered areas; these sites will be referred 

to as “Group 2 sites” (table 1). Samples collected 

during storm events in the basin also are included in 

this report. Typically, the storm data are limited to 

total-recoverable metal analyses from Group 1 sites.

The analytes of concern in this report are pH, 

copper, iron, and zinc. These analytes are consistent 

with the constituents of concern (COC) described in 

the draft Tier II ecological risk assessment; cyanide 
4 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

was identified as a COC but no data were available for 

comparison (Camp Dresser and McKee Inc., 1999). In 

addition, aluminum is not addressed in this report 

because no instream standards are applicable. 

Dissolved calcium and magnesium data collected in 

1998 and 1999 at selected tributary sites are used to 

estimate hardness at six of the sites sampled from 

1995 to 1997.

Data-Analysis Methods

The availability of water-quality data differed 

from site to site. Dissolved metal and anion data 

were not collected at Spring Creek, Fern Creek, 

Castleman Gulch, Silver Creek, Lieutenant Creek, and 

Ranger Creek (table 1). In addition, a high percentage 

of the total-recoverable copper and zinc data for these 

Group 2 sites were reported as censored values (less 

than the analytical reporting limit). In addition, 

comparisons of water-quality data to instream standards and TRVs differ depending on the use of aggregated or instantaneous data, stream reach in question, 

and aquatic biota of concern. In many cases, comparisons were site specific and various assumptions were 

required to adequately address the comparisons to 

instream standards or TRVs. The following sections 

describe the methodology used to address the various 

data concerns.

Estimation of Hardness for Selected Sites

Hardness is an integral component of many 

instream water-quality standards and TRVs. Dissolved 

calcium and magnesium concentrations are needed 

to calculate hardness (Hem, 1985). These data were 

not available for Group 2 sites during 1995–97 

(table 1). These sites were designated as miscellaneous 

water-quality sites and, as such, were sampled less 

often and only for total-recoverable metals (Edelmann 

and Ortiz, U.S. Geological Survey, written commun., 

1995 and 1997). However, water-quality samples 

collected at these same sites in October 1998 and June 

1999 included dissolved calcium and magnesium 

analyses (Kirk Nordstrom, U.S. Geological Survey, 

written commun., 1998). A comparison of the waterquality data collected from 1995 to 1997 and the data 

collected in 1998 and 1999 indicated that all six sites 

were similar in respect to pH, specific conductance, 

and metal concentrations. Since no substantial 

changes in land use had occurred along these six tributaries between 1995 and 1999, it was assumed that 

the hardness values in 1998 and 1999 are representative of hardness values from 1995 through 1997. 

Hardness values for Spring Creek, Fern Creek, 

Castleman Gulch, Silver Creek, Lieutenant Creek, 

and Ranger Creek in October 1998 and June 1999 

were grouped, and a regression equation was developed using specific conductance to predict hardness 

Table 1. Summary of water-quality data collected at tributary sites to the Alamosa River, southwestern Colorado, 1995–97

Site

name

Site 

number

Group

designation

Hydrothermal 

drainage 

area

Number 

of 

samples 

collected

Sampling 

frequency

(per year)

Sampling 

method

Analyte group

Totalrecoverable 

metals

Dissolved 

metals

Dissolved 

anions

Iron Creek IC0.0 1 Altered 29 7-9 Grab yes yes yes

Alum Creek AC0.0 1 Altered 31 7-9 Grab yes yes yes

Bitter Creek BI0.0 1 Altered 29 7-9 Grab yes yes yes

Wightman Fork WF0.0 1 Altered 117 7-9 Grab or 

automatic1

yes yes yes

Jasper Creek JC0.0 1 Altered 28 7-9 Grab yes yes yes

Burnt Creek BC0.0 1 Altered 17 7-9 Grab yes yes yes

Spring Creek SC0.0 2 Unaltered 12 4-5 Grab yes no no

Fern Creek FC0.0 2 Unaltered 13 4-5 Grab yes no no

Castleman Gulch CG0.0 2 Unaltered 16 4-5 Grab yes no no

Silver Creek SI0.0 2 Unaltered 13 4-5 Grab yes no no

Lieutenant Creek LC0.0 2 Unaltered 16 4-5 Grab yes no no

Ranger Creek RC0.0 2 Unaltered 15 4-5 Grab yes no no

1

 Multiple samples per day were collected at WF0.0 using a programmable automatic sampler installed at the site.
METHODS OF INVESTIGATION 5

(n=12, r2=0.975). Available specific conductance data 

from 1995 to 1997 were used in the regression equation (hardness=0.374 × specific conductance + 4.66) to 

estimate hardness values at each of the Group 2 sites.

Lack of Dissolved-Metal Data for Selected Sites

Dissolved-metal data are commonly used to 

define instream standards and TRVs. As described in a 

previous section, dissolved-metal data were not available for Spring Creek, Fern Creek, Castleman Gulch, 

Silver Creek, Lieutenant Creek, and Ranger Creek 

(table 1). It was assumed, however, that dissolved 

copper and zinc concentrations would constitute a 

large percentage of the total-recoverable metal fraction 

in these near-neutral-pH waters with little or no 

observable suspended-solid material. As such, a decision was made to compare dissolved copper and zinc 

standards to total-recoverable copper and zinc concentrations when no dissolved-metal data were available. 

This approach provided a conservative (worst case) 

approximation of the dissolved-metal concentration at 

these six sites.

The assumption stated above is not valid for 

iron concentrations in near-neutral water because 

dissolved iron concentrations generally are a small 

percentage of the total-recoverable concentrations. 

Therefore, a decision was made to apply a conversion 

factor to the available total-recoverable iron data 

collected at all Group 2 sites during 1995–97. This 

was accomplished by computing dissolved to totalrecoverable iron ratios for all paired data collected in 

1998 and 1999 at each of the six sites. The computed 

ratios ranged from 0.05 to 0.39 with a median of 0.16. 

The median ratio was then used as the conversion 

factor and was applied to all total-recoverable iron 

data collected at the six sites during 1995–97. The estimated dissolved iron concentrations were only used 

for comparisons to standards.

Use of Censored Data

A large percentage of the total-recoverable 

copper and zinc data for Spring Creek, Fern Creek, 

Castleman Gulch, Silver Creek, Lieutenant Creek, and 

Ranger Creek were reported as less than the analytical 

reporting limit. Helsel and Hirsch (1992) describe 

several methods to estimate summary statistics when 

data include censored values. The approach used in 

this report was to compare censored water-quality data 

to instream standards and TRVs using the reporting 

limit as the estimated concentration. This methodology produced a conservative (worst case) estimate 

of the metal concentration.

Copper data collected during August and 

September 1995 at Group 2 sites (table 1) were not 

compared to instream standards and TRVs because the 

reporting limits were affected by multiple dilutions of 

sample aliquots in the laboratories. These data were 

reported as censored values with reporting limits as 

much as 10 times greater than expected. As such, these 

data values were removed from the data set.

Comparison of Aggregated Data to Instream 

Standards

Numeric standards have been set for the Rio 

Grande Basin including the Alamosa River and its 

tributaries (Colorado Department of Public Health and 

Environment, 1998). Acute and chronic numbers 

adopted as stream standards are not to be exceeded 

more than once every 3 years on the average. It is 

recognized, however, that measured instream parameter values might exceed the standard approximately 

15 percent of the time (Colorado Department of Public 

Health and Environment, 1998). As such, an instream 

standard is exceeded if the 85th percentile value of the 

representative concentration data exceeds the instream 

standard value (P. Hegerman, Colorado Department 

of Public Health and Environment, oral commun., 

2000). With respect to pH in the Alamosa River Basin, 

exceedance of the standard would require that the 

15th percentile value was less than the standard value. 

Not all instream standards are set as a single 

numeric value. In some instances, standards may be 

established by site-specific adoption of the hardnessdependent equations (Colorado Department of Public 

Health and Environment, 1995). This approach 

utilizes applicable mean hardness values to calculate 

table value standards (TVS) for metals. In this study, 

mean hardness values were calculated using available 

data or estimated values as described in an earlier 

section.

Comparison of Instantaneous Data to Instream 

Standards and Toxicological Reference Values

Exceedances of USEPA TRVs are determined 

by comparing instantaneous data to the TRVs. For the 

purposes of this report, a decision was made also to 

compare instantaneous data to CDPHE instream 
6 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

standards. This decision allowed for comparisons of 

the percent exceedances of the TRVs and instream 

standards. Exceedances of the instream standards were 

determined only where applicable standards existed. It 

is worth noting that the term “exceedance” does not 

mean that a value is greater than the standard, only that 

it does not meet the criteria of the standard. In particular, a pH value less than the specified acceptable 

range is not in compliance; it “exceeds” the standard.

SUMMARY STATISTICS FOR SELECTED 

TRIBUTARY SITES

Summary statistics for selected water-quality 

characteristics are shown in table 2. The calculated 

statistics include the minimum, 25th percentile, 

median, 75th percentile, 85th percentile, and 

maximum value. The number of samples collected and 

the percentage of censored (less than) values also are 

shown. Multiply censored data accounted for more 

than 50 percent of the total-recoverable copper and 

zinc data collected at Group 2 sites. Quantile statistics 

(25th percentile, median, and 75th percentile) for these 

data were generated using maximum likelihood estimation methods (MLE) as described in Helsel and 

Cohn (1988). If more than 85 percent of the data was 

reported as censored values, the MLE was not applicable, and only the minimum and maximum values are 

shown in table 2. Hardness values for Group 2 sites 

were estimated using regression analysis of data 

collected in 1998 and 1999.

The water-quality characteristics of tributaries 

to the Alamosa River can be grouped according to the 

geologic nature of the basin the tributary drains 

(fig. 1). Iron Creek, Alum Creek, Bitter Creek, 

Wightman Fork, Jasper Creek, and Burnt Creek 

(Group 1 sites) all drain hydrothermally altered areas. 

Spring Creek, Fern Creek, Castleman Gulch, Silver 

Creek, Lieutenant Creek, and Ranger Creek (Group 2 

sites) all drain unaltered areas. Median values for 

nearly all measured characteristics at sites draining 

hydrothermally altered areas were higher than those 

from sites draining unaltered areas. The range of 

median values for Group 1 sites was 2.8 to 5.8 s.u. for 

pH; 172 to 1,560 μS/cm for specific conductance; 7.6 

to 962 μg/L for total-recoverable copper; 1,560 to 

163,000 μg/L for total-recoverable iron; and 11 to 766 

μg/L of total-recoverable zinc. In contrast, the range of 

median values for Group 2 sites was 7.2 to 7.8 s.u. for 

pH; 71 to 115 μS/cm for specific conductance; and 

136 to 516 μg/L for total-recoverable iron. Totalrecoverable copper and zinc concentrations for 

Group 2 sites were generally reported as “less than” 

values. Alkalinity values for Group 1 sites were 

consistently less than the reporting limit of 5 mg/L 

whereas alkalinity for Group 2 sites ranged from 26 to 

53 mg/L. For Group 1 sites, samples collected during 

storms invariably had the highest total-recoverable 

metal concentrations. Generally, a sample for 

dissolved metal analysis was not collected at these 

sites during storm events. No storm samples were 

collected at Group 2 sites.

COMPARISONS TO INSTREAM

STANDARDS AND TOXICOLOGICAL 

REFERENCE VALUES

The CDPHE established instream water-quality 

standards for stream segments in the Rio Grande 

Basin, including tributaries to the Alamosa River 

(Colorado Department of Public Health and Environment, 1998). Similarly, the draft Tier II Summitville 

Ecological Risk Assessment has established acute and 

chronic TRVs for aquatic biota in the Alamosa River 

Basin (Camp Dresser and McKee Inc., 1999). Standards were either a numeric standard or a calculated 

value. The general form of the equation for a calculated standard (STD) was:

STD = (expa × [ln (hardness)] ± b

) × m (1)

where

exp is the exponential e,

ln is the natural log,

hardness is the hardness value,

a is the slope of the log transformed data,

b is the adjusted intercept, and 

m is the conversion factor from total 

recoverable to dissolved concentrations.

The conversion factor, m, was specific to the 

calculation of TRVs and was not used for CDPHE 

instream standards (A. Patterson, Camp Dresser and 

McKee Inc., written commun., 2000). Mean hardness 

data were used to determine attainment or nonattainment of Colorado instream standards, as described in a 

previous section of this report. Instantaneous hardness 

values were used to determine instantaneous exceedances of TRVs or instream standards. 
COMPARISONS TO INSTREAM STANDARDS AND TOXICOLOGICAL REFERENCE VALUES 7

Table 2. Summary statistics for selected tributary sites in the Alamosa River Basin, 1995–97 

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; NA, not applicable; est, estimated;--, not reported]

Summary 

statistic

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Dissolved

Total 

recoverableDissolved

Total

recoverableDissolved

Total

recoverable

Iron Creek (IC0.0)1

Minimum 3.3 52 16 0 2 <4 68 1,400 9 9

25th percentile 3.7 81 23 -- 5 6 930 3,560 16 22

Median 4.2 172 35 -- 11 12 2,460 5,550 39 38

75th percentile 5.1 236 43 -- 15 19 3,770 9,120 48 59

85th percentile 5.3 331 52 -- 18 21 5,290 11,200 62 84

Maximum 5.9 472 67 5 21 3

 153 11,300 3 174,200 99 3 190

Number of 

samples

25 25 27 17 26 29 26 28 27 28

Percentage less 

than 

reporting 

limit

NA NA NA 100 12 7 0 0 0 4 

Alum Creek (AC0.0)1

Minimum 2.4 1,020 91 0 167 183 75,400 94,100 371 407

25th percentile 2.8 1,220 150 -- 217 222 132,500 140,500 660 640

Median 2.8 1,560 184 -- 250 257 148,000 163,000 815 766

75th percentile 2.9 1,730 239 -- 300 314 180,000 210,000 941 897

85th percentile 3.0 1,760 247 -- 327 375 195,200 244,700 970 961

Maximum 3.4 2,050 272 5 412 3

 1,460 254,500 3 3,260,000 1,000 3 1,940

Number of 

samples

25 25 27 17 27 31 27 31 27 31

Percentage less 

than 

reporting 

limit

NA NA NA 100 0 0 0 0 0 0 

Bitter Creek (BI0.0)1

Minimum 3.2 70 18 0 3 <1 1,100 2,670 9 12

25th percentile 3.4 174 48 -- 7 6 4,380 5,350 31 34

Median 3.6 374 86 -- 12 12 7,690 12,300 80 91

75th percentile 4.2 530 115 -- 17 21 12,700 14,100 118 120

85th percentile 4.6 558 126 -- 21 29 14,300 16,600 135 130

Maximum 5.1 616 140 5 65 3

 969 23,200 3 2,456,000 151 3 1,490

Number of 

samples

25 25 25 17 25 29 25 29 25 29

Percentage less 

than 

reporting 

limit

NA NA NA 100 8 14 0 0 0 0 
8 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Wightman Fork (WF0.0)1

Minimum 3.7 150 63 0 26 264 <4 635 129 190

25th percentile 4.5 313 105 -- 476 712 340 1,600 460 485

Median 4.8 598 177 -- 955 962 1,160 8,160 679 628

75th percentile 5.4 834 362 -- 1,800 1,990 4,600 15,050 1,040 1,050

85th percentile 6.3 904 404 -- 4,100 4,160 7,930 19,300 1,780 1,700

Maximum 7.8 2,470 840 24 8,410 3

 10,700 17,600 3 301,000 3,180 3 3,600

Number of 

samples

100 99 113 47 113 117 112 116 113 116

Percentage less 

than 

reporting 

limit

NA NA NA 55 0 0 3 0 0 0 

Jasper Creek (JC0.0)1

Minimum 4.1 58 24 0 1 <1 11 316 <3 <3

25th percentile 5.3 88 40 5 4 5 104 639 4 5

Median 5.8 182 84 5 5 8 195 1,560 8 11

75th percentile 6.8 282 163 11 10 13 414 3,730 22 24

85th percentile 7.2 411 223 12 18 17 543 5,090 37 36

Maximum 7.7 616 266 18 3

 56 3 1,000 3 2,800 3 1,420,000 3 78 3 1,400

Number of 

samples

25 25 26 19 26 28 26 28 26 28

Percentage less 

than 

reporting 

limit

NA NA NA 32 38 14 0 0 35 21 

Burnt Creek (BC0.0)1

Minimum 3.2 204 79 0 5 9 7 338 31 33

25th percentile 4.6 281 118 -- 10 14 44 1,580 36 60

Median 4.8 452 203 -- 14 20 135 3,400 70 91

75th percentile 5.1 540 291 -- 17 46 327 23,800 93 121

85th percentile 5.3 577 363 -- 19 336 354 184,700 97 466

Maximum 5.4 615 424 <5 3

 96 3 3,020 624 3 2,137,000 3 157 3 4,430

Number of 

samples

12 12 14 7 13 17 14 17 14 17

Percentage less 

than 

reporting 

limit

NA NA NA 71 0 0 14 0 0 0 

Table 2. Summary statistics for selected tributary sites in the Alamosa River Basin, 1995–97—Continued

s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

arbonate; <, less than; NA, not applicable; est, estimated;--, not reported]

Summary 

statistic

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Dissolved

Total 

recoverableDissolved

Total

recoverableDissolved

Total

recoverable
COMPARISONS TO INSTREAM STANDARDS AND TOXICOLOGICAL REFERENCE VALUES 9

Spring Creek (SC0.0)2,4

Minimum 6.8 64 est 29 29 -- -- -- 72 -- --

25th percentile 7.6 78 est 34 31 -- .73 -- 201 -- 1.98

Median 7.7 88 est 38 37 -- 1.31 -- 516 -- 3.04

75th percentile 8.0 127 est 52 46 -- 2.34 -- 820 -- 4.66

85th percentile 8.2 135 est 55 47 -- -- -- 1,110 -- --

Maximum 8.6 150 est 61 48 -- 5 -- 1,570 -- --

Number of 

samples

10 10 10 7 -- 10 -- 12 -- 12

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 70 -- 8 -- 67 

Fern Creek (FC0.0)2,4

Minimum 6.5 71 est 31 14 -- -- -- 60 -- --

25th percentile 6.9 84 est 38 22 -- .95 -- 237 -- 2.13

Median 7.8 106 est 51 26 -- 1.35 -- 476 -- 2.74

75th percentile 7.9 133 est 56 26 -- 1.93 -- 973 -- 3.51

85th percentile 8.0 142 est 60 28 -- -- -- 1,320 -- --

Maximum 8.2 191 est 76 30 -- -- -- 1,690 -- --

Number of 

samples

11 11 11 9 -- 11 -- 13 -- 13

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 73 -- 0 -- 77 

Castleman Gulch (CG0.0)2

Minimum 6.6 48 est 23 21 -- <1 -- 72 -- <3

25th percentile 6.9 64 est 29 27 -- -- -- 101 -- --

Median 7.2 71 est 31 34 -- -- -- 136 -- --

75th percentile 7.5 83 est 36 39 -- -- -- 176 -- --

85th percentile 7.7 87 est 37 42 -- -- -- 209 -- --

Maximum 7.8 98 est 41 48 -- 6 -- 354 -- <20

Number of 

samples

16 16 16 14 -- 14 -- 16 -- 16

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 86 -- 0 -- 87 

Table 2. Summary statistics for selected tributary sites in the Alamosa River Basin, 1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; NA, not applicable; est, estimated;--, not reported]

Summary 

statistic

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Dissolved

Total 

recoverableDissolved

Total

recoverableDissolved

Total

recoverable
10 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Silver Creek (SI0.0)2

Minimum 6.3 69 est 30 28 -- <1 -- 25 -- <3

25th percentile 7.3 80 est 35 33 -- -- -- 116 -- --

Median 7.8 104 est 44 38 -- -- -- 227 -- --

75th percentile 8.0 122 est 50 50 -- -- -- 428 -- --

85th percentile 8.1 124 est 51 53 -- -- -- 446 -- --

Maximum 8.4 136 est 56 57 -- <4 -- 725 -- <20

Number of 

samples

13 13 13 12 -- 12 -- 13 -- 13

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 92 -- 0 -- 100 

Lieutenant Creek (LC0.0)2,4

Minimum 6.8 94 est 40 35 -- <1 -- 130 -- --

25th percentile 7.8 103 est 43 48 -- -- -- 214 -- 1.97

Median 7.8 115 est 48 53 -- -- -- 344 -- 2.56

75th percentile 8.1 118 est 49 56 -- -- -- 521 -- 3.32

85th percentile 8.2 121 est 50 59 -- -- -- 565 -- --

Maximum 8.5 130 est 53 64 -- <5 -- 801 -- --

Number of 

samples

16 16 16 13 -- 14 -- 16 -- 16

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 86 -- 0 -- 81 

Ranger Creek (RC0.0)2,4

Minimum 6.9 63 est 28 16 -- <1 -- 61 -- --

25th percentile 7.5 71 est 31 31 -- -- -- 114 -- 1.10

Median 7.7 81 est 35 36 -- -- -- 174 -- 1.86

75th percentile 7.8 87 est 37 42 -- -- -- 405 -- 3.16

85th percentile 8.0 87 est 37 42 -- -- -- 535 -- --

Maximum 8.1 91 est 39 44 -- <4 -- 975 -- --

Number of 

samples

15 15 15 14 -- 13 -- 15 -- 15

Percentage less 

than 

reporting 

limit

NA NA NA 0 -- 92 -- 7 -- 80 

1

 Site drains hydrothermally altered areas; referred to as “Group 1” site in report.

2

 Site drains unaltered areas; referred to as “Group 2” site in report.

3

Samples were collected during a storm event.

4

Maximum likelihood estimation methods used to estimate median, 25th percentile, and 75th percentile values for copper and zinc.

Table 2. Summary statistics for selected tributary sites in the Alamosa River Basin, 1995–97—Continued

s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

arbonate; <, less than; NA, not applicable; est, estimated;--, not reported]

Summary 

statistic

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Dissolved

Total 

recoverableDissolved

Total

recoverableDissolved

Total

recoverable
COMPARISONS TO INSTREAM STANDARDS AND TOXICOLOGICAL REFERENCE VALUES 11

Tributaries in the Alamosa River Basin are classified by the CDPHE according to the beneficial use of 

the water, and classifications are assigned to specific 

stream segments. The 12 tributaries addressed in this 

report are included in either segment 4a, 6, 7, or 20 

(table 3). Applicable instream standards for each 

analyte of concern differed depending on the stream 

segment. Attainment or nonattainment of the CDPHE 

standards were examined for pH, copper, iron, and 

zinc prior to comparisons using instantaneous data. 

TRVs (table 4) were applicable to all tributary sites 

and were compared to instantaneous data.

pH Comparisons

Comparisons of the 15th percentile pH values to 

instream standards indicated that pH standards were in 

attainment at all tributary sites except Jasper Creek, 

where applicable pH instream standards were in effect. 

The 15th percentile value of 25 pH values taken at 

Jasper Creek was 5.0 s.u. compared to the instream 

standard value of 5.5 s.u. (table 3). Wightman Fork did 

not have an applicable instream pH standard.

Instantaneous exceedances of pH standards set 

by the CDPHE were relatively uncommon with the 

exception of Jasper Creek (table 5). Instantaneous pH 

values were less than the designated standard in 

35 percent of the Jasper Creek samples. Jasper Creek 

was the only tributary classified as “Aquatic Life—

Coldwater Class 2” (table 3).

The chronic pH TRV for rainbow trout and the 

acute and chronic pH TRV for benthic macroinvertebrates were exceeded between 74 and 100 percent of 

the time at Iron Creek, Alum Creek, Bitter Creek, 

Wightman Fork, and Burnt Creek (table 5). The acute 

TRV for rainbow trout also was exceeded from 8 to 

Table 3. Classifications and numeric standards for tributaries to the Alamosa River

[Colorado Department of Public Health and Environment, 1998; ln, natural log; e, exponential e; instream standards are shown as dissolved metal 

unless otherwise stated]

Site name Stream

segment Stream classification Applicable instream standard (in micrograms per liter)

Iron Creek, Alum Creek, 

Bitter Creek, Burnt Creek

4a 1Recreation–Class 2

2

Agriculture

pH = 2.5–9.0 standard units

Wightman Fork 6 1

Recreation–Class 2

2

Agriculture

No applicable standards 

Jasper Creek 7 1

Recreation–Class 2

2

Agriculture

3

Aquatic Life–Cold Water Class 2

pH = 5.5 to 9.0 standard units

Chronic copper = 90 (as total recoverable)

Chronic iron = 3,400 (as total recoverable)

Chronic zinc = 170 (as total recoverable)

Spring Creek, Fern Creek, 

Castleman Gulch, 

Silver Creek, 

Lieutenant Creek, 

Ranger Creek

20 1

Recreation–Class 2

2

Agriculture

4

Aquatic Life–Cold Water Class 1

pH = 6.5 to 9.0 standard units

Acute copper = e(0.9422 × [ln(hardness)] – 1.4634)

Chronic copper = e(0.8545 × [ln(hardness)] – 1.465)

Chronic iron = 300

Chronic iron = 1,000 (as total recoverable)

Acute zinc = e(0.8473 × [ln(hardness)] + 0.8604)

Chronic zinc = e(0.8473 × [ln(hardness)] + 0.7614)

1 These surface waters are suitable or intended to become suitable for recreational uses on or about the water included in secondary 

contact activities such as fishing and other streamside or lakeside recreation. 2

 These surface waters are suitable or intended to become suitable for irrigation of crops commonly grown in Colorado and are not 

hazardous as drinking water for livestock. 3

 These are waters that are not capable of sustaining a wide variety of cold- or warm-water biota due to physical habitat, water flows or 

levels, or uncorrectable water-quality conditions that result in substantial impairment of the abundance and diversity of species. 4

 These are waters that currently are capable of sustaining a wide variety of cold-water biota or could sustain such biota but for correctable water-quality conditions.
12 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

100 percent of the time at these five sites; Iron Creek 

(48 percent), Alum Creek (100 percent), and Bitter 

Creek (72 percent) had the highest percent exceedances. Alum Creek was the only site to exceed all four 

TRVs all of the time. Including exceedances at Jasper 

Creek, nearly all the observed exceedances of the 

TRVs were associated with sites that drain hydrothermally altered areas in the basin (fig. 1 and table 5).

Copper Comparisons

Comparisons of the 85th percentile copper 

concentrations to acute and chronic instream standards 

indicated that the standards were in attainment at all 

tributary sites where applicable copper instream standards were in effect. No applicable instream copper 

standard was in effect for Iron Creek, Alum Creek, 

Table 4. Toxicological reference values for aquatic biota in the Alamosa River Basin

[modified from draft Tier II Summitville Ecological Risk Assessment (Camp Dresser and McKee Inc., written commun., 2000); ln, natural log; e, 

exponential e; toxicological reference values are shown as dissolved metal unless otherwise stated]

Aquatic receptor Acute toxicological reference value 

(in micrograms per liter)

Chronic toxicological reference value 

(in micrograms per liter)

Rainbow trout pH = 4.2 standard units

copper = e(0.9016 × [ln(hardness)] – 0.562) × 0.960

iron = 1000 (as total-recoverable)

zinc = e(0.8390 × [ln(hardness)] + 2.6759) × 0.978

pH = 5.6 standard units

copper = e(0.8545 × [ln(hardness)] – 0.9895) × 0.960

iron = 1000 (as total recoverable)

zinc = e(0.8390 × [ln(hardness)] + 2.5710) × 0.986

Benthic macroinvertebrates pH = 5.38 standard units

copper = e(0.433 × [ln(hardness)] + 0.6050) × 0.960

iron = 320

zinc = e(1.23 × [ln(hardness)] + 1.039) × 0.978

pH = 6.5 standard units

copper = e(0.433 × [ln(hardness)] + 0.6050) × 0.960

iron = 320

zinc = e(0.6281 × [ln(hardness)] + 0.8473) × 0.986

Table 5. Percent instantaneous exceedance of instream pH standards and toxicological reference values for selected 

tributary sites in the Alamosa River Basin, 1995–97

[CDPHE, Colorado Department of Public Health and Environment; ERA, Ecological Risk Assessment; --, no applicable instream standard]

Site name

Stream 

segment

(fig. 1)

Hydrothermal 

drainage 

area

Instantaneous 

exceedance of 

CDPHE 

instream

standard

Summitville ERA toxicological reference value

Acute 

rainbow 

trout

Chronic 

rainbow 

trout

Acute 

benthic 

macroinvertebrate

Chronic 

benthic 

macroinvertebrate

Iron Creek 4a Altered 0 48 92 84 100

Alum Creek 4a Altered 8 100 100 100 100

Bitter Creek 4a Altered 0 72 100 100 100

Wightman Fork 6 Altered -- 15 79 74 86

Jasper Creek 7 Altered 36 4 44 28 64

Burnt Creek 4a Altered 0 8 100 83 100

Spring Creek 20 Unaltered 0 0 0 0 0

Fern Creek 20 Unaltered 0 0 0 0 0

Castleman Gulch 20 Unaltered 0 0 0 0 0

Silver Creek 20 Unaltered 8 0 0 0 8

Lieutenant Creek 20 Unaltered 0 0 0 0 0

Ranger Creek 20 Unaltered 0 0 0 0 0
COMPARISONS TO INSTREAM STANDARDS AND TOXICOLOGICAL REFERENCE VALUES 13

Bitter Creek, Burnt Creek, and Wightman Fork 

(table 3). Instream copper standards for Jasper Creek 

were based on total-recoverable concentrations.

Instantaneous exceedances of applicable copper 

standards set by the CDPHE occurred infrequently. 

Jasper Creek, Spring Creek, and Castleman Gulch 

were the only sites where exceedances occurred. No 

more than 11 percent of the instantaneous concentrations at the three sites exceeded the chronic copper 

instream standard (table 6). No instantaneous exceedances of the acute standard were observed.

The chronic copper TRV for rainbow trout

and the acute and chronic copper TRV for benthic 

macroinvertebrates were exceeded between 73 and 

100 percent of the time at Iron Creek, Alum Creek, 

and Wightman Fork (table 6). In addition, the acute 

TRV for rainbow trout was exceeded 31 percent of the 

time at Iron Creek and 100 percent of the time at Alum 

Creek and Wightman Fork. Alum Creek and 

Wightman Fork were the only sites to exceed all four 

TRVs all of the time. Exceedances of the TRVs for 

copper were associated only with sites that drain 

hydrothermally altered areas in the basin (fig. 1 and 

table 6). Copper concentrations analyzed from 

samples collected during rainstorms tended to exceed 

acute TRVs. Two of the three exceedances of the acute 

TRV for benthic macroinvertebrates in Jasper Creek 

were associated with storm runoff events; the acute 

TRV for rainbow trout was not exceeded during these 

storm runoff events.

Iron Comparisons

Comparisons of the 85th percentile dissolved 

iron concentrations to chronic agriculture standards 

indicated that iron standards were in attainment at all 

tributary sites where applicable agriculture standards 

were in effect. Agricultural standards for dissolved 

iron were in effect at Spring Creek, Fern Creek, 

Castleman Gulch, Silver Creek, Lieutenant Creek, and 

Ranger Creek (table 3). Aquatic-life standards, 

however, were based on total-recoverable iron concentrations (table 3). Chronic aquatic-life standards were 

not attained in Jasper Creek, Spring Creek, and Fern 

Creek (table 7). The 85th percentile concentration for 

Jasper Creek exceeded the standard of 3,400 μg/L by 

nearly 1,700 μg/L. Spring Creek and Fern Creek 

exceeded the standard of 1,000 μg/L by 110 and 

320 μg/L, respectively. No applicable instream 

Table 6. Percent instantaneous exceedance of instream copper standards and toxicological reference values for selected 

tributary sites in the Alamosa River Basin, 1995–97 

[CDPHE, Colorado Department of Public Health and Environment; ERA, Ecological Risk Assessment; --, no applicable instream standard; all instream 

standards and toxicological reference values are shown as dissolved copper unless otherwise stated]

Site

name

Stream 

segment

(fig. 1)

Hydrothermal 

drainage 

area

Instantaneous

exceedance of CDPHE 

instream standard

Summitville ERA toxicological reference value

Acute Chronic

Acute 

rainbow 

trout

Chronic 

rainbow 

trout

Acute 

benthic 

macroinvertebrate

Chronic 

benthic 

macroinvertebrate

Iron Creek 4a Altered -- -- 31 85 73 73

Alum Creek 4a Altered -- -- 100 100 100 100

Bitter Creek 4a Altered -- -- 4 28 36 36

Wightman Fork 6 Altered -- -- 100 100 100 100

Jasper Creek 7 Altered -- 1

 4 0 12 12 12

Burnt Creek 4a Altered -- -- 8 15 23 23

Spring Creek 20 Unaltered 0 11 0 0 0 0

Fern Creek 20 Unaltered 0 0 0 0 0 0

Castleman Gulch 20 Unaltered 0 8 0 0 0 0

Silver Creek 20 Unaltered 0 0 0 0 0 0

Lieutenant Creek 20 Unaltered 0 0 0 0 0 0

Ranger Creek 20 Unaltered 0 0 0 0 0 0

1

 Instream copper standard was based on total-recoverable concentrations.
14 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

standard for iron was in effect at Iron Creek, Alum 

Creek, Bitter Creek, Wightman Fork, and Burnt Creek 

(table 3).

Instantaneous exceedances of applicable iron 

standards set by the CDPHE occurred infrequently. 

Jasper Creek, Spring Creek, and Fern Creek were the 

only sites where exceedances occurred. Instantaneous 

concentrations measured at the three sites exceeded 

the chronic aquatic-life standard 17 to 29 percent of 

time (table 7). No instantaneous exceedances of the 

agriculture standard were observed.

The acute and chronic TRVs for rainbow trout 

and benthic macroinvertebrates were exceeded 

75 percent or more of the time at Iron Creek, Alum 

Creek, Bitter Creek, and Wightman Fork (table 7). In 

addition, the acute and chronic TRVs for rainbow trout 

were exceeded 88 percent of the time at Burnt Creek. 

Alum Creek and Bitter Creek were the only sites to 

exceed all four TRVs all of the time. 

Zinc Comparisons

Comparisons of the 85th percentile zinc concentrations to acute and chronic instream standards indicated that the standards were in attainment at all 

tributary sites where applicable zinc instream standards were in effect. No applicable instream zinc standard was in effect for Iron Creek, Alum Creek, Bitter 

Creek, Wightman Fork, and Burnt Creek (table 3). 

Instream zinc standards for Jasper Creek were based 

on total-recoverable concentrations.

Instantaneous exceedances of applicable zinc 

standards set by the CDPHE occurred only once at any 

tributary site. The chronic standard set for Jasper 

Creek (170 μg/L as total recoverable) was exceeded in 

a storm sample collected in August 1995; no acute 

standard is applicable at this site. No instantaneous 

exceedances of the acute standard were observed at 

any of the other sites.

The chronic zinc TRV for benthic macroinvertebrates was exceeded 50 percent or more of the time at 

Iron Creek, Alum Creek, Bitter Creek, Wightman 

Fork, and Burnt Creek (table 8). Wightman Fork was 

the only site to exceed all four TRVs. Acute rainbow 

trout TRVs were exceeded 34 percent of the time at 

Wightman Fork. Exceedances of the TRVs for zinc 

were generally associated with sites that drain hydrothermally altered areas (fig. 1 and table 8).

Table 7. Percent instantaneous exceedance of instream iron standards and toxicological reference values for selected tributary 

sites in the Alamosa River Basin, 1995–97

[CDPHE, Colorado Department of Public Health and Environment; ERA, Ecological Risk Assessment; --, no applicable instream standard; all instream standards and toxicological reference values are shown as dissolved iron unless otherwise stated]

Site

name

Stream 

segment 

(fig. 1)

Hydrothermal 

drainage

area

Instantaneous

exceedance of CDPHE 

instream standard

Summitville ERA toxicological reference value

Chronic 

aquatic life1

Chronic 

agriculture

Acute 

rainbow 

trout1

Chronic 

rainbow 

trout1

Acute 

benthic 

macroinvertebrate

Chronic 

benthic 

macroinvertebrate

Iron Creek 4a Altered -- -- 100 100 92 92

Alum Creek 4a Altered -- -- 100 100 100 100

Bitter Creek 4a Altered -- -- 100 100 100 100

Wightman Fork 6 Altered -- -- 89 89 75 75

Jasper Creek 7 Altered 29 -- 57 57 38 38

Burnt Creek 4a Altered -- -- 88 88 29 29

Spring Creek 20 Unaltered 17 0 17 17 0 0

Fern Creek 20 Unaltered 23 0 23 23 0 0

Castleman Gulch 20 Unaltered 0 0 0 0 0 0

Silver Creek 20 Unaltered 0 0 0 0 0 0

Lieutenant Creek 20 Unaltered 0 0 0 0 0 0

Ranger Creek 20 Unaltered 0 0 0 0 0 0

1 Instream standard and toxicological reference values were based on total-recoverable concentrations.
SUMMARY 15

SUMMARY

The U.S. Geological Survey collected waterquality data from 1995 through 1997 at 12 tributary 

sites to the Alamosa River. These data were used to 

address the data gaps identified in the initial ecological 

risk assessment of the Summitville Superfund site. 

Selected data were summarized to provide a general 

overview of the water quality of the tributaries. Tributaries to the Alamosa River can be grouped according 

to the geology of the basin the tributaries drain. Tributaries draining hydrothermally altered areas generally 

had higher median values than tributaries draining 

unaltered areas. In addition, samples collected during 

storms invariably had the highest total-recoverable 

metal concentrations.

Copper, iron, zinc, and pH data were compared 

to Colorado instream water-quality standards to determine if attainment of the standards had been met. 

Instantaneous data comparisons also were made to 

U.S. Environmental Protection Agency toxicological 

reference values (TRV) and Colorado instream standards. Instantaneous comparisons provided a means to 

determine the frequency at which a standard or TRV 

was exceeded.

Instream pH standards were in attainment at all 

tributary sites except Jasper Creek. Most instantaneous 

exceedances were associated with Jasper Creek. 

Chronic TRVs for rainbow trout, and acute and 

chronic TRVs for benthic macroinvertebrates were 

exceeded more than 70 percent of the time at Iron 

Creek, Alum Creek, Bitter Creek, Wightman Fork, and 

Burnt Creek. The acute TRV for rainbow trout was 

exceeded from 8 to 100 percent of the time at these 

five sites. 

Acute and chronic instream copper standards 

were in attainment at all tributary sites where applicable copper standards were in effect. Instantaneous 

exceedances of applicable instream standards occurred 

infrequently. Chronic TRVs for rainbow trout and 

acute and chronic TRVs for benthic macroinvertebrates were exceeded more than 70 percent of the 

time at Iron Creek, Alum Creek, and Wightman Fork. 

In addition, the acute TRV for rainbow trout was 

exceeded 31 percent of the time at Iron Creek and 

100 percent of the time at Alum Creek and Wightman 

Fork. 

Chronic agriculture standards for iron were in 

attainment at all tributary sites where applicable agriTable 8. Percent instantaneous exceedance of instream zinc standards and toxicological reference values for selected 

tributary sites in the Alamosa River Basin, 1995–97

[CDPHE, Colorado Department of Public Health and Environment; ERA, Ecological Risk Assessment; --, no applicable instream standard; all instream 

standards and toxicological reference values are shown as dissolved zinc unless otherwise stated]

Site

name

Stream 

segment 

(table 1)

Hydrothermal 

drainage

area

Instantaneous

exceedance of CDPHE 

instream standard

Summitville ERA toxicological reference value

Acute Chronic

Acute 

rainbow 

trout

Chronic 

rainbow 

trout

Acute 

benthic 

macroinvertebrate

Chronic 

benthic 

macroinvertebrate

Iron Creek 4a Altered -- -- 0 0 0 74

Alum Creek 4a Altered -- -- 0 0 0 100

Bitter Creek 4a Altered -- -- 0 0 0 92

Wightman Fork 6 Altered -- -- 34 4 22 100

Jasper Creek 7 Altered -- 1

 4 0 0 0 4

Burnt Creek 4a Altered -- -- 0 0 0 50

Spring Creek 20 Unaltered 0 0 0 0 0 0

Fern Creek 20 Unaltered 0 0 0 0 0 0

Castleman Gulch 20 Unaltered 0 0 0 0 0 0

Silver Creek 20 Unaltered 0 0 0 0 0 0

Lieutenant Creek 20 Unaltered 0 0 0 0 0 0

Ranger Creek 20 Unaltered 0 0 0 0 0 7

1 Instream standard was based on total-recoverable concentrations.
16 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

culture standards were in effect. Chronic aquatic-life 

standards for iron, however, were not attained at 

Jasper Creek, Spring Creek, and Fern Creek; instantaneous exceedances only occurred at these three sites. 

Acute and chronic TRVs for rainbow trout and benthic 

macroinvertebrates were exceeded 75 percent or more 

of the time at Iron Creek, Alum Creek, Bitter Creek, 

and Wightman Fork. In addition, the acute and chronic 

TRV for rainbow trout was exceeded 88 percent of the 

time at Burnt Creek. 

Instream zinc standards were in attainment at all 

tributary sites where applicable zinc instream standards were in effect. Instantaneous exceedances of 

applicable zinc standards occurred only once at any 

tributary site (Jasper Creek). The chronic TRV for 

benthic macroinvertebrates was exceeded 50 percent 

or more of the time at Iron Creek, Alum Creek, Bitter 

Creek, Wightman Fork, and Burnt Creek.

REFERENCES

Camp Dresser and McKee Inc., 1999, Tier II ecological risk 

assessment addendum for Summitville Mine Superfund site, Rio Grande, Conejos, Alamosa Counties, 

Colorado, draft report: Prepared by Camp Dresser and 

McKee Federal Programs Corporation for U.S. Environmental Protection Agency, November 1999.

Colorado Department of Public Health and Environment, 

1995, The basic standards and methodologies for 

surface water: Colorado Department of Public Health 

and Environment, Water Quality Control Commission, 

3.1.0 (5 CCR 1002–8), 49 p.

———1998, Classifications and numeric standards for Rio 

Grande basin: Colorado Department of Public Health 

and Environment, Water Quality Control Commission, 

Regulation Number 36, 37 p.

Helsel, D.R. and Cohn, T.A., 1988, Estimation of descriptive statistics for multiply censored water quality data: 

Water Resources Research, v. 24, No. 12, p. 1997–

2004. 

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods 

in water resources: New York, Elsevier Science 

Publishing Company Inc., 522 p.

Hem, J.D.,1985, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological 

Survey Water-Supply Paper 2254, 253 p.

Miller, M.W., and McHugh, J.B., 1994, Natural acid 

drainage from altered areas within and adjacent to the 

upper Alamosa River basin, Colorado: U.S. Geological 

Survey Open-File Report 94–144, 47 p.

Morrison-Knudsen Corporation, 1995, Tier I Ecological 

Risk Assessment, Summitville Mine site: Prepared 

under contract to U.S. Environmental Protection 

Agency, ARC contract number 68–W9–0025, July 

1995.

Stogner, R.W., 1996, Attenuation of metal concentrations in 

Terrace Reservoir, Conejos County, Colorado, May 

1994 through May 1995, in Hydrogeology of the San 

Luis Valley and environmental issues downstream 

from the Summitville mine: Geological Society of 

America, Field Guide, October 28–31, 1996, Denver, 

Colorado, not paginated.

Plumlee, G.S., and Edelmann, P.E., 1995, An update on 

USGS studies of the Summitville Mine and its downstream environmental effects: U.S. Geological Survey 

Open-File Report 95–23, 10 p.

Walton-Day, Katherine, Ortiz, R.F., and von Guerard, Paul, 

1995, Sources of water having low pH and elevated 

metal concentrations in the upper Alamosa River from 

the headwaters to the outlet of Terrace Reservoir, 

south-central Colorado, April–September, 1993, in

Posey, H.H., Pendelton, J.A., and Van Zyl, D., eds: 

Summitville Forum Proceedings, Colorado Geological 

Survey, Special Publication 38, p. 160–170.
APPENDIX
APPENDIX 19

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable

Iron Creek (IC0.0)

05-25-95 1005 5.4 81 23.8 2.9 <4 <4 924 3,240 15 21

06-07-95 1800 5.3 63 18.7 -- <5 6 421 4,730 13 18

06-15-95 1610 4.8 56 16.0 -- <5 8 168 9,020 10 22

06-30-95 1340 4.8 52 17.0 -- 2 4 520 1,400 11 11

07-25-95 1245 4.2 135 28.6 0 13 <5 -- -- 31 --

08-22-95 1030 4.1 168 35.7 -- 12 11 2,500 4,600 41 38

08-22-951 1830 -- -- 24.6 -- -- 69 68 98,000 18 150

09-26-95 1030 4.1 202 35.0 5.0 8 12 3,400 5,500 43 42

10-23-95 1440 3.7 374 66.0 5.0 21 20 11,300 13,500 92 82

04-25-96 1025 5.0 137 41.3 0 8 10 1,650 8,080 28 27

05-18-96 1120 5.9 67 19.4 -- 4 4 886 1,850 13 15

06-11-96 1250 4.7 175 36.1 -- 9 10 2,690 3,600 40 37

07-16-96 1105 3.7 302 50.8 <5.0 12 12 4,090 5,230 59 49

07-25-961 1430 -- -- -- -- -- 153 -- 174,200 -- 190

07-25-961 1555 -- -- -- -- -- 63 -- 18,600 -- 64

08-12-96 1555 3.3 445 67.2 0 18 19 5,070 4,880 99 85

09-17-96 1040 3.5 425 63.7 0 18 16 7,990 8,170 90 85

10-16-96 1245 3.4 472 61.1 0 16 14 9,270 9,940 89 91

03-25-97 1430 3.6 280 50.4 <5.0 14 15 3,840 6,620 49 53

04-24-97 1220 4.4 172 41.9 -- 10 12 2,990 6,250 42 40

05-14-97 1220 5.1 91 23.3 <5.0 4 10 1,050 11,300 16 25

05-28-97 1135 5.5 89 23.6 <5.0 4 6 1,317 3,090 21 22

06-05-97 1145 5.8 53 16.1 <5.0 4 5 431 2,100 9 9

06-17-97 1145 5.2 73 19.7 <5.0 5 4 949 1,640 16 13

07-15-97 1235 3.6 236 35.6 <5.0 13 14 2,420 3,420 44 38

07-21-971 1610 -- -- 32.9 -- 16 19 1,110 4,560 30 33

08-13-97 1320 4.1 208 35.4 <5.0 14 16 3,420 5,600 39 38

09-10-97 1305 4.1 222 39.7 <5.0 20 21 3,560 6,550 46 40

10-22-97 1245 3.5 236 44.7 -- 19 22 5,950 9,430 57 57
20 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Alum Creek (AC0.0)

04-27-95 1330 2.8 1,130 -- -- -- 369 -- 235,400 -- 827

05-25-95 0940 2.4 1,560 158 0 326 338 141,900 148,000 619 643

06-15-95 1420 3.0 1,100 91.0 -- 196 226 75,600 132,000 392 438

06-30-95 1625 2.9 1,120 -- -- -- 240 -- 110,000 -- 450

07-25-95 1230 2.7 1,450 142 0 260 237 129,000 124,000 700 638

08-22-95 1700 2.8 1,720 224 -- 300 280 173,000 159,000 930 830

09-14-951 1120 -- -- 209 -- 340 380 148,000 404,000 800 760

09-14-951 1345 -- -- 222 -- 340 320 170,000 204,000 870 730

09-26-95 1100 2.4 1,780 236 5.0 290 270 186,000 186,000 1,000 1,000

10-23-95 1435 2.8 1,710 249 5.0 250 240 186,000 173,000 1,000 880

04-25-96 0915 2.8 1,520 180 0 247 257 134,800 144,300 676 697

05-18-96 1350 3.4 1,216 123 -- 193 183 98,500 117,000 524 505

06-11-96 1510 2.9 1,470 179 -- 223 211 147,000 142,000 774 702

07-15-96 1625 2.8 1,780 247 <5.0 257 270 201,200 214,600 965 963

07-25-961 1420 -- -- -- -- -- 1,460 -- 3,260,000 -- 1,940

07-25-961 1605 -- -- -- -- -- 581 -- 484,000 -- 961

08-13-96 1125 3.2 1,680 255 0 229 218 148,000 139,000 966 852

08-23-961 1410 -- -- 267 -- 248 245 195,100 205,500 918 914

09-17-96 1040 2.9 1,730 272 0 236 208 164,000 150,000 1,000 937

10-16-96 1155 3.1 1,610 245 0 183 202 154,000 163,000 916 961

03-25-97 1700 2.8 2,050 170 <5.0 412 415 254,500 259,200 839 826

04-24-97 1015 2.7 1,760 184 -- 354 380 202,800 226,000 815 836

05-14-97 1520 2.7 1,150 99.3 <5.0 212 299 75,400 254,000 397 510

05-28-97 1430 2.9 1,520 143 <5.0 307 308 145,800 151,600 644 610

06-05-97 1355 3.0 1,020 92.4 <5.0 167 187 84,500 109,900 371 407

06-17-97 1445 2.7 1,160 115 <5.0 209 198 94,900 94,100 522 468

07-15-97 1325 2.8 1,470 158 <5.0 222 219 130,200 130,200 730 646

07-21-971 1620 -- -- 167 -- 203 225 147,500 163,800 715 743

08-13-97 1500 2.9 1,710 200 <5.0 269 269 154,100 151,700 834 766

09-10-97 1510 2.9 1,760 234 <5.0 266 253 174,000 165,000 952 851

10-22-97 1510 2.8 1,760 241 -- 300 298 196,000 199,400 1,000 970

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
APPENDIX 21

Bitter Creek (BI0.0)

04-27-95 1320 3.2 529 -- -- -- 38 -- 22,200 -- 112

05-25-95 1045 4.5 198 47.7 0 9 6 5,880 4,980 30 33

06-15-95 1315 5.1 70 20.0 -- <5 <5 1,160 7,680 16 22

06-30-95 1700 4.5 85 -- -- -- <1 -- 3,600 -- 17

07-25-95 1330 3.7 252 56.0 0 7 <5 4,380 4,920 51 46

08-22-95 1805 3.2 470 116 -- 33 30 12,700 12,300 110 98

09-26-95 1150 4.0 492 107 5.0 13 9 12,600 13,500 120 110

10-23-95 1620 3.4 548 138 5.0 12 12 14,600 14,100 140 120

04-25-96 1010 3.8 293 69.5 0 9 12 5,490 8,940 52 54

05-18-96 1515 4.7 99 25.0 -- 5 <3 2,030 4,430 19 20

06-11-96 1610 3.5 333 75.9 -- 6 7 6,770 6,790 77 70

07-15-96 1715 3.3 548 118 <5.0 20 21 7,690 8,590 118 112

07-25-961 1410 -- -- -- -- -- 969 -- 2,456,000 -- 1,490

07-25-961 1610 -- -- -- -- -- 126 -- 189,800 -- 242

08-13-96 1215 3.3 574 130 0 12 11 14,500 13,600 144 122

08-23-961 1440 -- -- 124 -- 22 26 13,500 14,300 132 131

09-17-96 1135 3.4 605 140 <1.0 14 14 14,200 13,300 151 142

10-16-96 1310 3.4 616 129 0 13 12 15,700 16,800 147 151

03-25-97 1720 3.2 606 111 <5.0 65 71 23,200 25,500 109 127

04-24-97 1515 3.6 333 75.6 -- 19 19 10,100 12,800 72 61

05-14-97 1615 3.9 174 39.7 <5.0 10 12 3,390 15,700 31 34

05-28-97 1540 4.2 138 33.2 <5.0 3 5 3,390 4,310 27 26

06-05-97 1450 4.9 140 18.2 <5.0 <4 5 1,110 5,350 9 12

06-17-97 1515 4.8 101 24.8 <5.0 4 3 2,010 2,670 17 15

07-15-97 1455 3.2 374 78.8 <5.0 7 6 4,740 4,920 79 70

07-21-971 1630 -- -- 85.6 -- 9 13 5,530 6,420 80 82

08-13-97 1600 3.7 481 97.7 <5.0 28 27 12,600 13,900 97 91

09-10-97 1550 3.5 530 112 <5.0 17 17 12,200 11,800 114 116

10-22-97 1600 3.5 471 109 -- 14 19 12,500 12,900 112 109

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
22 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Wightman Fork (WF0.0)

02-23-95 1110 7.5 1,520 369 -- 205 747 <15 1,000 386 411

03-15-95 1225 7.4 645 192 -- 78 679 <5 2,670 344 418

04-27-95 1120 6.8 302 113 -- 57 743 31 2,690 177 --

05-09-95 1310 7.8 298 113 -- 51 634 49 2,910 146 237

05-24-95 1220 6.3 205 64.3 3.4 336 560 1,220 8,630 266 295

06-16-95 0610 4.8 283 64.8 -- 841 875 2,100 9,260 502 499

06-29-95 1230 4.2 546 107 -- 3,000 2,900 11,000 16,000 1,300 1,300

07-26-95 1200 -- -- 162 0 5,970 5,620 12,600 20,000 2,440 2,270

07-26-95 1205 3.8 870 165 0 5,580 5,240 12,500 18,600 2,350 2,170

07-26-95 1620 3.8 869 162 0 5,330 5,000 12,100 17,700 2,280 2,140

07-26-95 2005 3.7 978 185 -- 8,410 8,080 17,600 30,300 3,180 3,020

07-27-95 0005 3.7 882 164 0 6,380 6,190 14,600 20,900 2,610 2,340

07-27-95 0405 3.7 883 149 -- 6,190 6,560 12,500 23,900 2,550 2,530

07-27-95 0805 3.8 861 154 0 5,330 5,320 10,500 19,900 2,270 2,280

08-21-951 1630 4.1 512 127 -- 1,800 3,500 620 301,000 1,100 1,600

08-21-951 2359 4.1 668 141 -- 4,100 4,000 6,500 34,700 1,800 1,600

08-23-95 1130 -- -- 183 -- 4,500 4,600 9,400 14,400 2,000 1,900

08-23-95 1135 4.4 726 171 -- 4,300 4,200 7,500 12,100 1,900 1,700

08-23-95 1937 4.3 793 178 -- 4,700 4,500 8,100 13,600 2,100 1,900

08-24-95 0337 4.3 791 177 -- 4,800 4,900 7,500 12,600 2,000 1,900

09-14-95 1345 -- -- 225 5.0 7,200 7,600 15,900 26,800 2,800 2,600

09-14-951 1430 4.6 848 -- -- -- 5,000 -- 15,100 -- 1,800

09-14-951 1945 4.2 1,080 -- -- -- 10,700 -- 54,400 -- 3,600

09-15-951 0300 4.3 893 -- -- -- 1,200 -- 12,800 -- 2,000

09-27-95 1030 -- -- 207 1.1 4,100 4,300 10,400 12,900 1,600 1,600

09-27-95 1235 4.8 866 207 1.0 4,200 4,200 8,800 11,200 1,600 1,500

09-27-95 2045 4.7 985 251 1.2 4,700 4,400 14,800 15,800 2,000 1,700

09-28-95 0440 4.7 819 234 1.0 5,200 5,000 10,600 12,700 1,900 1,700

10-24-95 1030 5.1 1,160 303 1.2 4,100 4,100 7,700 8,200 1,800 1,600

11-21-95 1615 5.0 1,670 403 -- 3,300 3,400 6,700 8,800 1,400 1,400

02-22-96 1335 5.8 2,470 541 -- 942 1,224 1,900 3,260 771 789

03-27-96 1115 6.6 2,030 459 -- 412 558 109 2,740 570 582

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
APPENDIX 23

Wightman Fork (WF0.0)—Continued

04-24-96 1125 7.7 637 172 24.4 101 264 97 2,010 129 190

05-16-96 0900 -- -- 96.1 2.2 322 397 1,380 11,700 343 341

05-16-96 1105 5.2 381 118 -- 375 398 1,860 3,910 354 319

05-16-96 1505 4.9 381 115 -- 492 540 2,850 12,000 482 460

05-16-96 1905 5.0 257 79.1 -- 243 388 974 24,600 325 362

05-16-96 2305 5.2 273 81.9 -- 276 327 888 7,200 290 296

05-17-96 0305 5.2 320 91.9 -- 326 339 1,030 4,180 316 289

05-17-96 0705 5.2 354 106 2.2 355 383 1,310 4,320 339 326

06-10-96 1545 6.7 639 287 2.1 150 459 17 1,140 340 325

06-11-96 1400 -- -- 272 1.8 203 438 44 951 349 318

06-11-96 1600 6.7 598 287 -- 129 446 <4 1,020 329 331

06-11-96 2000 6.6 620 297 -- 222 472 15 1,210 388 387

06-11-96 2359 6.4 554 265 -- 263 502 143 1,290 367 364

06-12-96 0400 6.5 543 251 -- 145 450 24 1,220 322 330

06-12-96 0800 6.6 584 272 -- 188 468 56 989 338 346

06-12-96 1200 6.7 584 280 2.4 146 477 23 1,020 336 356

07-17-96 1430 -- -- 362 <5.0 1,060 1,250 483 14,680 788 818

07-17-96 1630 5.2 801 366 -- 645 712 644 1,580 615 547

07-17-96 2030 5.8 754 364 -- 582 717 506 1,450 597 543

07-18-96 0030 6.0 788 377 -- 521 775 403 1,850 589 558

07-18-96 0430 4.5 893 430 -- 3,060 3,220 45 64,900 1,920 1,780

07-18-96 0830 4.8 801 393 -- 1,090 1,070 922 4,910 888 776

07-18-96 1230 5.1 794 408 <5.0 862 830 871 2,160 735 634

07-25-961 1630 -- -- -- -- -- 917 -- 2,260 -- 595

08-13-96 1220 -- -- 476 <1.0 981 973 536 1,080 710 599

08-13-96 1420 5.3 930 574 <1.0 863 921 507 1,010 625 562

08-13-96 2220 5.5 372 489 -- 655 789 202 951 574 513

08-14-96 0220 5.4 345 446 -- 1,740 1,700 1,120 1,650 971 852

08-14-96 1020 5.4 995 466 <1.0 1,370 1,300 801 1,430 894 749

08-22-961 1330 4.5 661 250 -- 1,950 1,990 1,140 8,120 1,250 1,260

08-22-961 2130 4.7 582 227 -- 1,490 1,560 1,090 8,680 1,040 1,070

08-23-961 0130 4.4 683 256 <5.0 2,660 2,780 2,860 41,400 1,770 1,790

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
24 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Wightman Fork (WF0.0—Continued

08-23-961 0930 4.2 642 235 -- 1,840 1,880 1,050 17,400 1,310 1,310

08-23-961 1730 4.5 610 249 <5.0 1,330 1,330 1,200 5,680 1,040 1,040

09-16-96 1425 5.6 1,570 834 <1.0 759 830 650 1,430 638 600

09-17-96 1215 -- -- 800 <1.0 865 922 792 2,430 663 622

09-17-96 1415 5.3 1,330 676 <1.0 741 843 366 1,300 591 566

09-17-96 2215 5.4 1,620 840 -- 715 807 694 1,270 575 548

09-18-96 1015 5.1 1,570 801 -- 865 922 871 2,620 672 641

10-16-96 0920 4.6 1,640 739 <5.0 305 701 161 958 460 508

11-20-96 1120 6.6 523 218 14.0 162 913 7 1,610 451 520

02-19-97 1030 6.1 507 227 7.1 241 636 <10 635 532 553

03-26-97 1045 7.5 295 112 23.4 26 396 5 3,200 129 210

04-22-97 1140 4.9 356 118 -- 1,220 1,270 3,390 16,900 716 689

05-13-97 1125 5.2 184 63.0 <5.0 290 417 844 8,270 271 293

05-14-97 1000 -- -- 63.8 <5.0 476 577 754 17,400 349 364

05-14-97 1200 4.8 175 65.2 -- 429 487 1,360 10,500 332 338

05-14-97 2000 4.6 165 65.1 -- 468 621 741 24,600 359 376

05-14-97 2359 4.6 161 64.7 -- 534 666 632 19,400 384 408

05-15-97 0800 4.8 150 64.2 <5.0 484 562 680 10,400 337 353

05-28-97 0945 -- -- 86.4 <5.0 973 926 3,270 9,290 562 507

05-28-97 1145 4.5 306 101 -- 1,190 1,150 4,580 9,560 660 597

05-28-97 1545 4.5 296 98.5 -- 1,140 1,060 4,500 9,710 641 560

05-28-97 1945 4.6 241 76.9 -- 806 776 2,460 10,800 488 442

05-28-97 2345 4.5 250 69.3 -- 895 799 -- -- 524 468

05-29-97 0345 4.5 262 84.2 -- 922 895 2,960 8,360 546 496

05-29-97 0745 4.5 264 88.4 <5.0 1,020 964 3,430 8,510 576 515

06-03-97 0900 -- -- 82.4 <5.0 1,420 1,600 4,680 26,300 686 761

06-03-97 1100 4.0 352 97.1 -- 1,840 1,990 6,430 16,500 839 915

06-03-97 1500 4.0 329 85.3 -- 1,450 1,580 5,330 32,400 704 764

06-03-97 1900 4.3 228 66.6 -- 990 1,210 2,910 37,100 502 585

06-03-97 2300 4.1 250 74.8 -- 1,270 1,410 3,870 19,100 612 670

06-04-97 0300 4.0 267 85.4 -- 1,560 1,690 5,130 15,000 732 782

06-04-97 0700 4.0 286 92.2 <5.0 1,710 1,880 5,960 15,400 798 876

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
APPENDIX 25

Wightman Fork (WF0.0)—Continued

06-16-97 1630 -- -- 113 -- 2,310 2,240 9,410 29,200 1,120 976

06-18-97 1000 -- -- 107 <5.0 1,360 1,320 4,190 8,510 728 655

06-18-97 1200 4.1 442 134 -- 2,270 2,190 8,280 13,300 1,120 1,020

06-18-97 1600 4.1 427 127 -- 2,120 2,100 7,830 13,500 1,060 1,010

06-18-97 2000 4.5 279 91.7 -- 922 891 2,130 6,550 531 490

06-18-97 2359 4.6 283 97.5 -- 955 925 2,180 6,200 548 514

06-19-97 0800 4.7 296 105 <5.0 1,050 1,010 2,830 6,660 593 540

07-15-97 1130 -- -- 378 <5.0 974 951 85 915 731 663

07-15-97 1330 4.8 753 359 -- 885 923 151 998 718 616

07-15-97 1730 4.8 770 373 -- 957 986 97 711 745 656

07-15-97 2130 4.9 798 390 -- 949 962 58 817 732 640

07-16-97 0130 4.9 732 361 -- 894 888 53 708 679 578

07-16-97 0530 5.0 742 363 -- 885 904 54 884 699 610

07-16-97 0930 5.0 758 372 <5.0 908 933 114 982 716 663

08-13-97 1400 -- -- 140 <5.0 1,390 1,390 1,520 4,040 968 992

08-13-97 1600 4.7 482 143 -- 1,400 1,420 1,920 4,410 985 954

08-13-97 2359 4.7 408 142 -- 1,400 1,400 1,460 4,160 988 953

08-14-97 0400 4.8 400 140 -- 1,370 1,330 1,170 3,310 945 913

08-14-97 1200 4.8 394 137 <5.0 1,360 1,370 1,630 3,650 959 924

09-11-97 1005 5.2 1,010 557 <5.0 922 899 261 1,160 762 647

10-23-97 0930 5.7 850 434 <5.0 656 793 583 1,250 540 527

Jasper Creek (JC0.0)

04-27-95 1315 5.4 182 -- -- -- 13 -- 4,640 -- 16

05-25-95 1215 6.8 86 31.4 12.6 <4 4 148 1,850 <4 5

06-15-95 1145 7.5 61 23.5 -- <5 <5 100 2,230 <4 7

06-30-95 1743 5.4 71 -- -- -- <1 -- 610 -- <5

07-25-95 1420 6.5 130 52.3 12.2 <5 <5 326 491 <4 <4

08-22-951 1725 -- -- 171 -- 52 1,000 240 1,420,000 78 1,400

08-22-95 1905 4.2 260 103 -- 29 28 1,000 6,000 21 22

09-26-95 1250 5.3 370 162 4.6 <30 5 1,100 1,700 24 28

10-23-95 1745 5.1 472 217 3.1 6 8 430 1,600 22 23

04-25-96 1230 7.5 137 56.1 18.4 5 7 133 3,500 <4 8

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
26 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Jasper Creek (JC0.0)—Continued

05-18-96 1300 7.7 85 34.5 -- 4 <3 169 756 4 4

06-11-96 1745 5.1 184 75.9 5.6 <3 3 11 433 <3 <3

07-15-96 1845 4.8 189 164 <5.0 9 16 488 1,620 17 12

08-13-96 1255 4.1 616 266 0 15 17 321 394 44 41

08-23-961 1530 -- -- 245 -- 56 53 2,800 5,360 67 66

09-17-96 1240 5.6 571 254 <1.0 11 10 266 333 37 36

10-16-96 1605 4.8 587 244 <5.0 11 12 451 712 38 37

03-26-97 1415 5.5 223 83.6 <5.0 7 13 365 4,400 11 22

04-24-97 1715 5.6 140 53.7 -- <4 12 118 5,110 10 14

05-14-97 1715 7.1 91 33.2 6.6 5 27 190 18,900 <5 32

05-28-97 1630 6.6 74 29.8 10.4 2 4 152 649 3 <3

06-05-97 1600 7.4 58 24.3 13.2 4 7 96 818 <4 <4

06-17-97 1600 6.1 88 35.5 12.4 4 3 201 443 <3 <3

07-15-97 1555 5.8 157 63.3 <5.0 1 2 27 316 <3 4

07-21-971 1900 -- -- 83.7 -- <4 7 94 1,440 7 8

08-13-97 1655 7.0 204 84.5 5.0 <3 9 53 1,840 5 12

09-10-97 1635 6.1 309 131 <5.0 <3 5 19 917 9 12

10-22-97 1635 6.3 282 125 6.1 <4 13 710 1,510 13 17

Burnt Creek (BC0.0)

04-27-95 1410 3.2 529 -- -- -- 27 -- 11,300 -- 95

04-27-95 1830 -- -- -- -- -- 46 -- 23,800 -- 103

05-25-95 1335 4.9 250 96.2 2.8 -- 11 199 1,190 31 35

06-15-95 1010 5.4 204 78.6 -- 5 12 378 5,330 32 42

06-30-95 1800 4.8 434 -- -- -- 19 -- 3,400 -- 75

08-24-951 1735 -- -- 185 -- 11 1,300 <40 890,000 47 1,700

04-25-96 1320 4.7 615 298 0 12 16 33 2,540 86 87

05-18-96 1225 4.5 580 271 -- 16 14 260 338 96 91

08-23-961 1555 -- -- 424 -- 17 19 26 1,240 115 121

08-23-961 1840 -- -- 363 -- 20 3,020 7 2,137,000 96 4,430

03-26-97 1450 4.6 575 247 <5.0 17 39 55 19,500 73 113

04-24-97 1740 4.9 470 204 -- 14 21 71 770 73 67

05-14-97 1810 5.3 274 105 <5.0 10 476 <60 290,000 35 648

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
APPENDIX 27

Burnt Creek (BC0.0)—Continued

05-28-97 1700 5.1 284 118 <5.0 8 9 624 1,580 36 33

06-05-97 1645 5.4 285 118 <5.0 6 12 353 2,090 36 37

06-17-97 1630 4.5 476 203 <5.0 19 20 248 1,940 67 60

07-21-971 1850 -- -- 371 -- 96 127 349 26,900 157 192

Spring Creek (SC0.0)

04-27-95 1425 -- -- -- -- -- 5 -- 1,570 -- 7

05-25-95 1240 7.5 64 est 28.6 -- -- <4 -- 1,420 -- 6

06-15-95 1645 -- -- -- -- -- <5 -- 780 -- 7

08-23-95 1700 8.3 150 est 60.8 45.0 -- -- -- 96 -- 4

09-27-95 1015 8.6 138 est 56.3 48.0 -- -- -- <90 -- <10

04-25-96 1400 7.6 64 est 28.6 -- -- <4 -- 729 -- <4

05-13-97 1000 6.8 87 est 37.0 31.0 -- 3 -- 939 -- <20

05-27-97 1705 7.7 79 est 34.2 29.2 -- 2 -- 504 -- <3

06-05-97 1356 7.8 78 est 33.8 31.9 -- <4 -- 528 -- <4

06-17-97 1440 7.3 90 est 38.3 36.7 -- <1 -- 245 -- <3

07-14-97 1555 7.6 129 est 52.9 47.3 -- <1 -- 72 -- <3

08-12-97 1325 8.0 122 est 50.3 -- -- <3 -- 236 -- <4

Fern Creek (FC0.0)

04-27-95 1435 -- -- est 42.1 -- -- <4 -- 1,260 -- 5

05-25-95 1330 -- -- est 32.7 -- -- <4 -- 1,690 -- 4

07-26-95 1511 6.8 139 est 56.6 -- -- <5 -- 60 -- <4

08-23-95 1615 8.2 155 est 62.6 29.0 -- -- -- 330 -- 4

09-27-95 1110 7.9 191 est 76.1 26.0 -- -- -- 94 -- <10

04-25-96 1410 6.5 106 est 44.3 17.0 -- <4 -- 973 -- <4

05-16-96 1605 7.0 124 est 51.0 22.0 -- <3 -- 156 -- <3

05-13-97 0930 6.6 92 est 39.1 30.0 -- 3 -- 1,540 -- <20

05-27-97 1815 7.2 71 est 31.2 14.0 -- 2 -- 596 -- <3

06-05-97 1330 7.8 75 est 32.7 24.0 -- <4 -- 740 -- <4

06-17-97 1515 8.0 84 est 36.2 25.5 -- 1 -- 476 -- <3

07-14-97 1635 7.8 130 est 53.3 25.8 -- <1 -- 237 -- <3

08-12-97 1245 7.8 133 est 54.4 -- -- <3 -- 260 -- <4

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
28 Characterization of Water Quality in Selected Tributaries of the Alamosa River, Southwestern Colorado, Including Comparisons 

to Instream Water-Quality Standards and Toxicological Reference Values, 1995–97

Castleman Gulch (CG0.0)

06-29-95 1118 7.6 48 est 22.6 21.0 -- <1 -- 120 -- <5

07-26-95 1430 6.8 66 est 29.3 -- -- <5 -- 141 -- <4

08-23-95 1530 7.8 82 est 35.3 36.0 -- -- -- 100 -- 6

09-27-95 1155 7.7 85 est 36.4 36.0 -- -- -- 98 -- <10

04-25-96 1440 6.6 98 est 41.3 42.0 -- <4 -- 204 -- <4

05-16-96 1525 7.3 64 est 28.6 27.0 -- <3 -- 101 -- <3

06-11-96 1045 7.1 66 est 29.3 38.0 -- <3 -- 72 -- <3

07-16-96 1020 6.9 77 est 33.5 42.0 -- <4 -- 116 -- <4

08-13-96 1330 6.6 87 est 37.2 48.0 -- 6 -- 141 -- 5

09-16-96 1545 7.4 93 est 39.4 39.0 -- <3 -- 75 -- <3

05-13-97 0835 7.0 71 est 31.3 33.0 -- <3 -- 242 -- <20

05-27-97 1845 7.0 57 est 26.0 23.7 -- <1 -- 167 -- <3

06-05-97 1255 7.8 63 est 28.2 26.6 -- <4 -- 211 -- <4

06-16-97 1700 6.6 61 est 27.4 23.7 -- 1 -- 146 -- <3

07-14-97 1700 7.5 71 est 31.2 30.1 -- <1 -- 354 -- <3

08-12-97 1200 7.3 75 est 32.7 -- -- <3 -- 132 -- <4

Silver Creek (SI0.0)

06-29-95 1030 8.3 80 est 34.6 34.0 -- <1 -- 160 -- <5

09-27-95 1245 8.1 136 est 55.5 54.0 -- -- -- 140 -- <10

04-25-96 1430 7.6 85 est 36.4 37.0 -- <4 -- 227 -- <4

05-16-96 1750 7.1 113 est 46.9 38.0 -- <3 -- 70 -- <3

06-11-96 1125 7.4 122 est 50.3 49.0 -- <3 -- 25 -- <3

07-16-96 1200 6.3 122 est 50.3 52.0 -- <4 -- 113 -- <4

09-17-96 1455 8.0 134 est 54.8 57.0 -- <3 -- 374 -- <3

05-13-97 1255 7.0 79 est 34.4 30.0 -- <3 -- 437 -- <20

05-28-97 1345 7.3 71 est 31.2 28.2 -- <1 -- 243 -- <3

06-05-97 1225 7.8 69 est 30.5 27.6 -- <4 -- 482 -- <4

06-16-97 1610 8.4 88 est 37.7 35.9 -- 2 -- 428 -- <3

07-14-97 1815 7.8 117 est 48.4 46.7 -- <1 -- 725 -- <3

08-12-97 1105 7.9 104 est 43.6 -- -- <3 -- 116 -- <4

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable
APPENDIX 29

Lieutenant Creek (LC0.0)

06-29-95 0915 8.4 100 est 42.1 -- -- <1 -- 170 -- <5

07-26-95 1250 6.8 116 est 48.0 -- -- <5 -- 138 -- <4

08-23-95 1440 8.2 116 est 48.0 54.0 -- -- -- 220 -- 5

09-27-95 0910 7.8 121 est 49.9 53.0 -- -- -- 130 -- <10

04-25-96 1445 8.1 120 est 49.5 59.0 -- <4 -- 398 -- <4

05-16-96 1445 7.8 130 est 53.3 64.0 -- <3 -- 801 -- 4

06-11-96 1155 8.5 114 est 47.3 54.0 -- <3 -- 429 -- <3

07-16-96 1100 7.8 117 est 48.4 51.0 -- <4 -- 518 -- <4

08-13-96 1405 7.4 114 est 47.3 59.0 -- <3 -- 221 -- <3

09-17-96 1430 8.1 123 est 50.7 56.0 -- <3 -- 289 -- <3

05-13-97 1340 7.8 96 est 40.5 45.0 -- <3 -- 608 -- <20

05-28-97 1735 7.9 94 est 39.8 35.2 -- <1 -- 577 -- <3

06-05-97 1145 7.6 102 est 42.8 47.8 -- 4 -- 421 -- <4

06-16-97 1540 7.2 103 est 43.2 48.0 -- 1 -- 530 -- 4

07-14-97 1850 7.9 117 est 48.4 41.4 -- <1 -- 194 -- <3

08-12-97 1015 8.0 110 est 45.8 -- -- <3 -- 223 -- <4

Ranger Creek (RC0.0)

06-29-95 0825 7.6 75 est 32.7 31.0 -- <1 -- 120 -- <5

08-23-95 1350 8.1 86 est 36.8 44.0 -- -- -- 61 -- 10

09-27-95 1320 8.1 89 est 38.0 41.0 -- -- -- <90 -- <10

04-25-96 1505 7.5 72 est 31.6 36.0 -- <4 -- 468 -- <4

05-16-96 1350 7.7 91 est 38.7 37.0 -- <3 -- 101 -- <3

06-11-96 1220 7.8 80 est 34.6 41.0 -- <3 -- 113 -- <3

07-16-96 1125 6.9 85 est 36.4 44.0 -- <4 -- 211 -- <4

08-13-96 1435 7.3 87 est 37.2 42.0 -- <3 -- 117 -- 4

09-17-96 1510 8.0 87 est 37.2 42.0 -- <3 -- 199 -- <3

05-13-97 1415 7.7 63 est 28.3 28.0 -- <3 -- 975 -- <20

05-28-97 1800 7.8 69 est 30.5 16.2 -- <1 -- 561 -- <3

06-05-97 1115 7.5 67 est 29.7 32.6 -- <4 -- 543 -- <4

06-16-97 1505 7.3 69 est 30.6 32.1 -- 1 -- 342 -- 3

07-14-97 1935 7.8 86 est 36.8 27.8 -- <1 -- 116 -- <3

08-12-97 0910 7.8 81 est 35.0 -- -- <3 -- 174 -- <4

1 Storm sample collected on this date.

Table 9. Instantaneous pH, specific conductance, and selected chemical data for selected tributary sites to the Alamosa River, 

1995–97—Continued

[s.u., standard units; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; CaCO3, calcium 

carbonate; <, less than; est, estimated]

Sample collection

pH

(s.u.)

Specific 

conductance

(μS/cm)

Hardness

(mg/L as 

CaCO3)

Alkalinity

(mg/L)

Copper

(μg/L)

Iron

(μg/L)

Zinc

(μg/L)

Date Time Dissolved

Total

recoverable

Dissolved

Total

recoverable

Dissolved

Total

recoverable