U.S. Department of the Interior

U.S. Geological Survey

Data Series 253

Prepared in cooperation with the City of Longmont

Aquatic Communities and Selected Water Chemistry in 

St. Vrain Creek near the City of Longmont, Colorado, 

Wastewater-Treatment Plant, 2005 and 2006
Front cover photograph: St. Vrain River downstream from Airport Road at Golden Ponds Nature Area, 

Longmont Colorado, late April 2005.
Aquatic Communities and Selected Water 

Chemistry in St. Vrain Creek near the 

City of Longmont, Colorado, WastewaterTreatment Plant, 2005 and 2006

By Robert E. Zuellig, Lori A. Sprague, Jim A. Collins, and Oliver N. Cox

Prepared in cooperation with the City of Longmont

Data Series 253

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Zuellig, R.E., Sprague, L.A., Collins, J.A., and Cox, O.N., 2007, Aquatic communities and selected water chemistry in 

St. Vrain Creek near the City of Longmont, Colorado, wastewater-treatment plant, 2005 and 2006: U.S. Geological 

Survey Data Series 253, 30 p.
iii

Contents

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

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

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

Study Area.......................................................................................................................................................3

Approach and Results...................................................................................................................................4

Historical Data on Aquatic Communities..........................................................................................4

Fish Communities.........................................................................................................................4

Trouts (Salmonidae)............................................................................................................5

Minnows (Cyprinidae)........................................................................................................5

Suckers (Catostomidae) ....................................................................................................8

Bullhead Catfishes (Ictaluridae).......................................................................................8

Killifishes (Fundulidae).......................................................................................................9

Livebearers (Poeciliidae)...................................................................................................9

Sticklebacks (Gasterosteidae) .........................................................................................9

Sunfishes (Centrarchidae) ..............................................................................................10

Perches (Percidae)...........................................................................................................10

Macroinvertebrate Communities ............................................................................................10

Biological Data Synopsis..........................................................................................................11

Wastewater Compounds ...................................................................................................................12

Travel-Time Estimation..............................................................................................................12

Rhodamine-WT Injection and Sampling .......................................................................12

Lagrangian Synoptic .................................................................................................................13

Hydrophobic Organic Compounds...................................................................................................13

Acknowledgments.......................................................................................................................................14

References Cited..........................................................................................................................................28

Figure

1. Map showing St. Vrain Creek Basin, Colorado, with land use, designated stream 

segments, and sampling stations...............................................................................................2

Tables

1. Sites sampled for water chemistry in the study reach in Longmont, Colorado .................3

2. Travel-time results for the April 5, 2005, tracer study, St. Vrain Creek ..............................13

3. Travel-time results for the March 14, 2006, tracer study, St. Vrain Creek.........................14

4. Data from the analysis of wastewater compounds and associated field properties .....15

5. Percent difference between environmental and replicate samples and percent 

recovery of spike concentrations of wastewater compounds ...........................................25

6. Data from the toxicity assays conducted on dialysates from the semipermeable 

membrane devices .....................................................................................................................27
iv

Conversion Factors, Datums, and Acronyms

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Flow rate

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

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

°F=(1.8×°C)+32

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

(NAVD 88).

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

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

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

25°C).

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

or micrograms per liter (μg/L).

Acronyms

USGS U.S. Geological Survey

SPMDs semipermeable membrane devices

AhR aryl hydrocarbon receptor

PAHs polycyclic aromatic hydrocarbons

PCBs polychlorinated biphenyls

WWTP wastewater-treatment plant

CDOW Colorado Division of Wildlife

INHS Illinois Natural History Survey

LFL Larval Fish Laboratory, Colorado State University, Fort Collins, Colorado

TEQs toxic equivalents
Aquatic Communities and Selected Water Chemistry 

in St. Vrain Creek near the City of Longmont, Colorado, 

Wastewater-Treatment Plant, 2005 and 2006

By Robert E. Zuellig, Lori A. Sprague, Jim A. Collins, and Oliver N. Cox

Abstract

In 2005, the U.S. Geological Survey and the City of 

Longmont, Colo., began a study to document chemical 

characteristics of St. Vrain Creek that had previously been 

unavailable either due to high cost of analysis or lack of analytical capability. Stream samples were collected at seven sites 

on St. Vrain Creek during the spring of 2005 and 2006 for 

analysis of wastewater compounds. A Lagrangian-sampling 

design was followed during each sampling event, and time-oftravel studies were conducted just prior to each sampling event 

to determine appropriate sampling times for the synoptic. In 

addition, semipermeable membrane devices, passive samplers that concentrate hydrophobic organic chemicals, were 

installed at six sites during the spring of 2005 and 2006 for 

approximately 4 weeks. After retrieval, contaminant residues 

concentrated in the semipermeable membrane devices were 

recovered and used in a toxicity assay that provided a screen 

for aryl hydrocarbon receptor type compounds, including 

polycyclic aromatic hydrocarbons, polychlorinated biphenyls, 

dioxins, and furans.

In addition, the U.S. Geological Survey summarized 

information on macroinvertebrate and fish communities known 

from St. Vrain Creek dating back to the early 1900s in order 

to assess their utility in evaluating wastewater-treatment plant 

upgrades and habitat improvement projects. Unfortunately, 

because of inconsistencies in data collection these data cannot 

be used as intended; however, they are useful for understanding to some degree gross patterns in fish species distribution, 

but less so for macroinvertebrates.

Introduction

The St. Vrain Creek Basin in northeastern Colorado 

(fig. 1) has experienced rapid urban growth over the last 

two decades. As a result, some agricultural land in the lower 

half of the basin has been converted to urban land to accommodate the growing population in and around the cities of 

Longmont and Boulder. This population growth has led to 

an increase in treated waste volumes being processed at the 

wastewater-treatment plants (WWTPs) in the basin. In the 

last two decades, in-stream restoration efforts and new waste 

treatment technologies have been implemented by the City 

of Longmont, with the goal of improving water quality and 

aquatic organism community structure downstream from 

WWTP effluent.

WWTP upgrades primarily were designed to address 

conventional issues such as elevated nutrients, metals, and 

suspended-solids concentrations. The Longmont WWTP has 

been monitoring these compounds regularly to determine 

the efficacy of plant upgrades in decreasing concentrations 

in the effluent. However, recent studies have indicated that 

additional, previously unmonitored compounds are present in surface water downstream from WWTPs (Kolpin and 

others, 2002). These organic wastewater chemicals, which 

include detergents, disinfectants, fragrances, fire retardants, 

nonprescription drugs, and pesticides, can be released to the 

environment through discharges from industrial facilities, 

animal feed lots, WWTPs, and individual septic disposal systems, or through runoff from land applications in agricultural 

and urban areas. Some of these chemicals have been shown to 

disrupt endocrine systems in fish (Thorpe and others, 2001; 

Schreurs and others, 2004), increase antibiotic resistance of 

bacteria (McMurry and others, 1998), and shift the community 

structure of algae (Wilson and others, 2003). In addition to 

human waste, the Longmont WWTP also receives industrial 

waste from poultry and dairy operations and biotechnology 

and metals processing facilities; as a result, it is probable that 

some of these wastewater chemicals are present in St. Vrain 

Creek. As there is currently no information on the presence 

of such compounds in the Longmont WWTP effluent or in 

St. Vrain Creek, it is difficult to begin to assess their potential 

impacts on aquatic communities in the stream.

Another class of compounds that may be present in the 

Longmont WWTP effluent and in surface runoff from the 

surrounding urban areas both up and downstream from the 

WWTP discharge location are hydrophobic contaminants such 

as polychlorinated dioxins and furans, polycyclic aromatic 

hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), 

organochlorine insecticides, and pyrethroid insecticides. Many 
!

!

!

!

!

!

!

! !

!

!

#

#

#

#

Coal Creek

Boulder Creek

Left Hand Creek

Dry Creek

Saint Vrain

Creek

South Saint Vrain Creek

South Boulder Creek

Middle Boulder Creek

Dry Creek

Dry Creek

MEAD

WARD ERIE

LYONS

BOULDE

R

SUPERIOR

LONGMON

T

NEDERLAND

LAFAYETTE

JAMESTOWN

LOUISVILLE

105°15’ 105°

105°

40°

40°15’

105°30’

40°

40°15’

105°30’

!

DENVER

South Platte River

"

119

119Th St.

287

Weld County Road 1

Boston Avenue 

rport Road Ai M4

T8 M6

O1 M8

M9

T1

Longmont Diagonal

Ken Pratt

C O L O R A D O

Hygiene Road

N 75th St.

Hover Road

North Saint Vrain Creek 

Segment 1

Segment 2

Segment 3

Base modified from U.S. Geological Survey 1:100,000 digital data, 2003Land cover modified from U.S. Geological Survey National Land Cover 30-meter resolution, 1992; data resampled to 1-kilometerRoads modified from StreetMap USA, 1:50,000 digital data, 2006Albers Equal-Area Conic projectionStandard parallels 29°30’ and 45°30’, central meridian -104°00’ 

EXPLANATION

ForestGrassland/pastureCroplandUrban/residentialShrublandWetlandBare rockWaterIce/snow

5 MILES

5 KILOMETERS

0 2.50 2.5

Creek

Saint

Dry Creek

Site

Additional tracer site

Wastewater treatment plant

Dry Creek

Left Hand Creek

Vrain

Boulder Creek

105°15’

Figure 1. St. Vrain Creek Basin, Colorado, with land use, designated stream segments, and sampling stations.

   Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 1. Sites sampled for water chemistry in the study reach in Longmont, Colorado.

[Abbreviation: USGS, U.S. Geological Survey]

Site number1 USGS station number Site name

M9 401011105084701 St. Vrain Creek below Airport Road at Longmont

M8 400919105051501 St. Vrain Creek 50 feet above Left Hand Creek at Longmont

T1 400918105051601 Left Hand Creek 30 feet above mouth at Longmont

O1 400920105051001 Wastewater outflow on St. Vrain Creek at Longmont

M6 400911105042500 St. Vrain Creek at North 119th Street near Longmont

T8 400928105003401 Boulder Creek 400 feet above mouth at Longmont

M4 400937105002901 St. Vrain Creek at Highway 119 near Longmont

1

 Location of sites shown in figure 1.

of these compounds have been shown to be toxic to aquatic 

organisms. However, they are not routinely monitored by the 

Longmont WWTP owing to the high cost of laboratory analysis and the difficulty in detecting them at their typically low 

concentrations. Even at low concentrations, these compounds 

may still be bioaccumulated by aquatic organisms. Semipermeable membrane devices (SPMDs), passive samplers that 

are designed to mimic the bioaccumulation of organic contaminants in the fatty tissues of aquatic organisms, concentrate 

trace levels of hydrophobic organic contaminants in aquatic 

systems over time (Huckins and others, 1990). Extracts from 

the sequestering media in the SPMD can be used in toxicity 

tests that provide a relatively inexpensive means of assessing 

potential toxicity at a particular location in the stream.

In 2005, the U.S. Geological Survey (USGS), in cooperation with the City of Longmont, began a study to document 

selected chemical characteristics of St. Vrain Creek that had 

previously been unavailable either due to high cost of analysis 

or lack of analytical capability. In addition, the USGS summarized information on macroinvertebrate and fish communities known from St. Vrain Creek dating back to the early 

1900s. These historical biological data were summarized to 

assess their utility in evaluating WWTP upgrades and habitat 

improvement projects facilitated by the City of Longmont.

Purpose and Scope

This report describes results from a study whose objectives were to (1) review and summarize available information 

regarding fish and macroinvertebrate communities in St. Vrain 

Creek below Hygiene Road in Longmont to the confluence 

with Boulder Creek, and (2) supplement the current monitoring program in place at the Longmont WWTP with an assessment of additional chemical factors that may be affecting 

biological communities.

Sampling during the study included wastewater chemicals 

and toxicity of hydrophobic organic contaminants. St. Vrain 

Creek was sampled along an 8.6 mile reach beginning a few 

miles upstream from the WWTP outfall and ending at the 

confluence with Boulder Creek. Additionally, macroinvertebrate samples were collected in April of 2005 and 2006 at 

selected sites within the study reach and delivered to the City 

of Longmont where they worked with a local consulting company to process the samples.

Study Area

St. Vrain Creek originates along the Continental Divide 

in northeastern Colo. (fig. 1). The headwater streams travel 

through primarily forested land until they exit the mountains 

and converge near Lyons, Colo., to form St. Vrain Creek 

(Litke and Kimbrough, 1998). The St. Vrain then travels east 

through primarily agricultural land to the city of Longmont. 

After flowing through Longmont, the St. Vrain continues 

east through agricultural land to its confluence with the South 

Platte River near Platteville, Colo., approximately 15 miles 

away.

Water chemistry sampling for this study was conducted 

at seven sites along the study reach (table 1). Two sites were 

on St. Vrain Creek upstream from the WWTP outfall (M9 and 

M8); two sites were at the mouths of the major tributaries, Left 

Hand Creek and Boulder Creek (T1 and T8); one site was at 

the WWTP outfall (O1), and two sites were on St. Vrain Creek 

downstream from the outfall (M6 and M4). Site M9, located at 

Airport Road on the western edge of Longmont, represented 

inputs to St. Vrain Creek upstream from most of the urbanizing area in and around Longmont. Site M8, located immediately upstream from the WWTP outfall, represented inputs 

from upstream urban and agricultural inputs prior to the input 

of treated WWTP effluent. Site T1 was located at the mouth 

of Left Hand Creek and site T8 was located at the mouth of 

Boulder Creek; these are the two largest tributaries entering St. Vrain Creek in the study reach. Site M6 was located 

approximately 1 mile downstream from the outfall with no 

intervening tributaries, and site M4 was located just downstream from the confluence of St. Vrain Creek and Boulder 

Creek (previous sampling by the City of Longmont at 

Study Area 
site M4 was upstream from the Boulder Creek confluence). 

Due to the limited scope of the study, all tributaries and storm 

drains along the study reach were not sampled.

Approach and Results

Historical Data on Aquatic Communities

Available information on macroinvertebrate and fish communities was reviewed from previously published literature, 

the Colorado Division of Wildlife (CDOW) fish database, and 

from holdings at the Illinois Natural History Survey (INHS) 

in Urbana, Illinois, and the C.P. Gillette Museum of Arthropod Diversity at Colorado State University in Fort Collins, 

Colorado. The Larval Fish Laboratory (LFL, Colorado State 

University, Fort Collins, Colo.) also was contacted but they did 

not have any historical records of fish from St. Vrain Creek in 

their holdings. An exhaustive search of additional museums 

was not made because much of this historical information was 

previously incorporated in the literature and the CDOW fish 

database. Additional records of fish from St. Vrain Creek may 

exist in other museum holdings but likely do not include new 

species records for this drainage. Although a comprehensive 

knowledge of aquatic community structure prior to the many 

hydrologic, water quality, and habitat alterations made to 

St. Vrain Creek is unavailable, much more is known about fish 

than macroinvertebrates.

Fish Communities

The first known fish collections from the plains portion 

of St. Vrain Creek did not take place until the early 1900s 

(Juday, 1904, 1905). Although these collections took place 

more than 100 years ago, they occurred well after many alterations in hydrology, water quality, and habitat had occurred 

in the area (Fausch and Bestgen, 1996). Because of the lack 

of information prior to these alterations, it is difficult to get 

a clear picture of historical fish distribution and abundance 

patterns in St. Vrain Creek prior to 1900. Information on 

early fish distribution patterns in Boulder County is available 

primarily as a result of the early collections by Juday (1904, 

1905) from Boulder and St. Vrain Creeks. Ellis (1914) was 

the first to publish a comprehensive recollection of the fishes 

of Colorado, which included collections from 1912 and 1913, 

earlier published accounts, and holdings at the University of 

Colorado at Boulder including those of Juday (1904, 1905). 

Hendricks (1950) later summarized his and the early collections of fishes from Boulder County prior to 1950, providing 

additional knowledge about fish community structure in the 

lower St. Vrain and Boulder Creeks. Hendricks noted that 

several species had been eliminated based on his collections 

by that time. In 1952, Beckman published a guide to the fishes 

of Colorado, providing a taxonomic key for identification 

but did not include specific collection locality information. 

Later, Li (1968) described the early surveys of the South Platte 

River Basin, including the early work in St. Vrain Creek, 

and reconciled some of the probable misidentifications and 

nomenclature changes in the historic record. During the early 

1970s local consultants and Colorado State University graduate students conducted several surveys to assess the influence 

of the Fort St. Vrain power plant operations on biological 

communities near the confluence of St. Vrain Creek and 

South Platte River (downstream from the study reach). Propst 

(1982) further sorted out historical accounts and led a major 

effort to describe the distribution, ecology, and community 

dynamics of fishes of the plains portion of the South Platte 

River Basin (Propst and Carlson 1986). Propst’s work included 

sampling St. Vrain Creek in the late 1970s. Several collections have occurred since that time that were part of comprehensive inventories of the South Platte River system (Nesler 

and others, 1997), were sporadic collections that provided 

little comprehensive information (unpublished data in CDOW 

fish database), or were not available for review (data from 

Schrader, 1989).

Few direct comparisons of site-specific species abundance or richness can be made using the assembled fish data 

from St. Vrain Creek because of the variety of methods used, 

the variability in space and time of sampling, the unknown 

level of reliability associated with each collection, and the 

uncertainty around the consistency of species reported during 

earlier sampling. For example, some records in the CDOW 

fish database reported only one species for a sampling event 

when certainly more were present. Additionally, notes in the 

database were unfortunately often incomplete and included 

very little information on capturing methods and amount of 

effort used prior to the data collected by Nesler and others 

(1997). Furthermore, there was very little consistency regarding which sites were sampled across seasons and years. 

Although these data may not be useful for assessing sitespecific trends in abundance and richness in St. Vrain Creek, 

they are useful for understanding to some degree gross patterns in species distribution along the entire study reach. 

Because of the sporadic nature of collections at various sites 

and times, species occurrences are described by distinct 

segments as follows: segment 1 includes sites from Airport 

Road upstream to Hygiene Road, segment 2 includes sites 

from Airport Road downstream to the WWTP, and segment 3 

includes sites from the WWTP downstream to Boulder Creek.

Below is a brief summary of the known distribution and 

historic accounts of fishes found in lower St. Vrain Creek from 

Hygiene Road downstream to the confluence with Boulder 

Creek. Much of this historic information regarding the occurrence of fish species in St. Vrain Creek has been previously 

summarized by earlier workers as part of larger scale studies 

such as investigations of the fishes of Boulder County (Juday, 

1904, 1905; Hendricks, 1950), the South Platte River Basin 

in Colorado (Li, 1968, Propst, 1982; Propst and Carlson, 

1986; Nesler and others, 1997), the Great Plains portion of 

Colorado (Fausch and Bestgen, 1996), and of Colorado (Ellis, 

1914; Beckman, 1952; Woodling, 1985). Species accounts 

 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
and information from the above publications and other sources 

mentioned earlier are summarized by the first known collection records of the species from St. Vrain Creek, generalizations about which river segment a species occurred in, brief 

notes on habitat and spawning requirements, and species status 

in Colorado and elsewhere when applicable.

Trouts (Salmonidae)

Various non-native trout species are routinely stocked in 

gravel pits and reservoirs in the upper reaches of the plains 

portion of St. Vrain Creek near the plains-mountain interface 

for recreational opportunities, but only one species, brown 

trout (Salmo trutta), has been reported from the study reach 

(CDOW fish database). Brown trout are consistently collected 

in low numbers upstream from Hover Road and become more 

abundant in samples closer to the plains-mountain interface. 

Occasionally, brown trout are collected below Hover Road. 

Historically, native greenback cutthroat trout (Oncorhynchus 

clarki stomias) likely inhabited the uppermost reaches of the 

plains portion of St. Vrain Creek (Behnke, 1992) and possibly 

through the study reach, especially during high snowmelt runoff years. Historical overfishing and especially the introduction of other salmonids are apparent causes of greenback 

cutthroat disappearance across its native South Platte range 

(Behnke, 1992). Potentially increased water temperatures 

associated with water withdrawal for irrigation purposes near 

the plains-mountain interface possibly further influenced 

downstream fish communities. Greenback cutthroat trout was 

federally listed as endangered in 1973. Since that time, several 

locations in the headwaters of St. Vrain Creek Basin have been 

used as reintroduction sites as part of the recovery plan for this 

federally listed species. Currently, greenback cutthroat trout is 

federally and state listed as threatened (Schmidt, 2006). There 

are no known records of this species from the study reach.

Minnows (Cyprinidae)

Central stoneroller (Campostoma anomalum) is considered common in the South Platte River system (Nesler and 

others, 1997). When present, it is usually not a dominant 

component of total fish abundance (Propst, 1982). It inhabits 

foothill streams to the lower reaches of the South Platte River 

but is usually not found in reaches influenced by organic 

enrichment (Woodling, 1985). Typical habitat requirements 

include sand-gravel-bottomed pools and riffles with some 

current. In Missouri, this species requires streams with permanent flow and well-defined riffles with gravel, rubble, or 

bedrock substrate (Pflieger, 1997). This species has specialized mouthparts to feed on algae but also intakes midge larva, 

some plant tissue, sand, and clay (Schrader, 1989 and citations 

within). Clean gravel, moderately clear water, and a nearby 

pool are requirements for spawning (Schrader, 1989 and 

citations within; Cross and Collins, 1995). Juday (1905) first 

reported central stoneroller from the lower St. Vrain River at a 

site presumably near Highway 287 (segment 2). This species 

is consistently collected at sites upstream from the WWTP 

(segments 1 and 2) and occasionally downstream in segment 3 

(CDOW fish database). This species is listed as a species of 

concern in North Dakota (Schmidt, 2006).

Native to eastern Asia, goldfish (Carassius auratus) 

was introduced into Colorado in the 1870s (Wiltzius, 1981). 

When present, goldfish never make up a large portion of the 

fish community in terms of abundance in stream habitats in 

Colorado (CDOW fish database). Goldfish have been occasionally collected in St. Vrain Creek probably as a result of 

well-meaning people releasing their unwanted pets. The influence of goldfish on plains fish communities is unknown but is 

probably minimal because they are rarely collected in stream 

systems. The earliest records of goldfish in St. Vrain Creek are 

from the early 1900s as reported by Juday (1905).

Lake chub (Couesius plumbeus) was considered extirpated from the South Platte River Basin (Propst, 1982) until 

a single specimen was collected from South Fork St. Vrain 

Creek upstream of Lyons in 1989 (Bestgen and others, 1991). 

Since that time it has been collected from reservoirs in the 

upper Poudre River and Clear Creek Basins (Nesler and 

others, 1997; Kevin Bestgen, Larval Fish Laboratory, Colorado State University, oral commun., 2006) and recently from 

a private reservoir on Middle Fork St. Vrain Creek and from 

Barker Reservoir in Nederland (Harry Crockett, Colorado 

Division of Wildlife, oral commun., 2006). Historical records 

from the early 1900s are from St. Vrain and Boulder Creeks 

(Juday, 1904, 1905; Ellis, 1914; Bestgen and others, 1991; 

Nesler and others, 1997). Adults are primarily insectivores 

and have generalized spawning requirements (Schrader, 1989 

and citations within). Lake chub is state listed as endangered 

in Colorado and Massachusetts and is a species of concern 

in Illinois, North Dakota, Washington, and Wyoming (Nesler 

and others, 1997; Patton, 1997; Schmidt, 2006). Currently, 

this species appears to be limited to upper-elevation lakes and 

reservoirs with rocky shorelines. Most recent records are from 

lake habitats with rocky shorelines, whereas historical records 

are primarily from transition zone stream habitats. In Wyoming, lake chub is found in a variety of habitats including both 

small streams and lakes (Baxter and Stone, 1995). More effort 

is needed to better understand its distribution in Colorado and 

in the St. Vrain Basin (Nesler and others, 1997).

Red shiner (Cyprinella lutrensis) is considered common 

in the South Platte River system (Nesler and others, 1997) and 

is tolerant of many natural variations in physical and chemical 

conditions (Propst, 1982). It is typically associated with eddies 

formed by trees, debris piles, and riprap as well as large pools 

and is most common in the lower reaches of the South Platte 

River and its tributaries (Propst, 1982). Red shiner is considered an opportunistic feeder that primarily feeds on insects 

(Pflieger, 1997) and has generalized spawning requirements 

(Schrader, 1989 and citations within). The earliest records 

of this species in St. Vrain Creek are from the collections 

of Juday made in the early 1900s (Ellis, 1914). Red shiner 

has been collected both upstream and downstream from the 

WWTP (segments 1, 2, and 3) but is more consistently collected in segment 3 (CDOW fish database).

Approach and Results   
Native to Europe, common carp (Cyprinus carpio) was 

introduced into Colorado in 1879 (Wiltzius, 1981) and since 

has been found in most warm water river systems and reservoirs in the State (Woodling, 1985). This species tolerates a 

wide variety of environmental conditions, including organically enriched water below wastewater and industrial effluents. 

Large schools of feeding carp can disrupt the spawning of 

other species and increase turbidity in shallow water systems 

(Woodling, 1985). In St. Vrain Creek, carp are commonly 

collected in segments 2 and 3 in the study reach (CDOW fish 

database). The influence of this species on native plains fish in 

Colorado is unknown.

Brassy minnow (Hybognathus hankinsoni) was once 

considered common in the South Platte River Basin (Ellis, 

1914); however, its distribution has been significantly reduced 

in Colorado (Propst, 1982; Nesler and others, 1997). Brassy 

minnow is tolerant of a wide range of physical and biological 

conditions associated with harsh plains environments. This 

species mostly consumes algae but also feeds on zooplankton, 

phytoplankton, aquatic insects, and plants and requires aquatic 

vegetation for spawning (Schrader, 1989 and citations within). 

The decline of brassy minnow is assumed to be a result of 

habitat reduction and possibly poor water quality. Slowmoving pools and flooded backwater habitats are important 

for the persistence of this species. In the Arikaree River in 

eastern Colorado, basin-wide movements were required by 

brassy minnow in order to move between spawning, rearing, 

and over-summering and over-wintering habitat (Scheurer and 

Fausch, 2003). In the plains portion of St. Vrain Creek, brassy 

minnow is occasionally collected both upstream and downstream from the WWTP (CDOW fish database). Brassy minnow is state listed as threatened in Colorado and is currently 

listed as rare, a species of special concern, or is a candidate 

species for listing in Illinois, Kansas, Missouri, Vermont, British Columbia, and Quebec (Nesler and others, 1997; Schmidt, 

2006). The plains portion of St. Vrain Creek is vital to the persistence of brassy minnow in transition zone stream habitats in 

the South Platte River Basin. More work is warranted in these 

habitats to better understand requirements of brassy minnow 

occurrence in transition zone streams.

Common shiner (Luxilus cornutus) distribution is localized in the South Platte River Basin, found mainly in St. Vrain 

Creek and the Upper South Platte tributary system (Nesler and 

others, 1997). Generally, this species requires streams with 

moderate gradient and cool, clear water, and silt-free gravel, 

overhung by riparian vegetation. Common shiner is apparently 

sensitive to habitat changes due to siltation events (Nesler 

and others, 1997). Diet consists of algae, aquatic plants, and 

aquatic insects (Schrader, 1989 and citations within). Common 

shiner generally spawns in moving water over gravel or rubble 

and is known to use spawning nests of other species such as 

creek chub or hornyhead chub (Cross and Collins, 1995). Earliest collection records in St. Vrain Creek are from the early 

1900s, presumably upstream from the WWTP in segment 2 

(Juday, 1905). In St. Vrain Creek, common shiner is routinely 

collected from all stream segments but is most consistently 

found upstream from the WWTP in segments 1 and 2 (CDOW 

fish database). Efforts have been made by the CDOW to 

enhance current populations of common shiner in the St. Vrain 

Basin by selective stocking (Randy Van Buren, Colorado 

Division of Wildlife, oral commun., 2005). Currently, common 

shiner is state listed as threatened due to its decline in distribution and abundance in Colorado and is a species of concern 

in Wyoming (Nesler and others, 1997; Schmidt, 2006). In 

Colorado, most of the decline on record has occurred since 

the late 1970s (Nesler and others, 1997). The lower St. Vrain 

and tributaries are critical for the consistent well-being of this 

species in transition-zone stream habitats in Colorado. More 

work is warranted in the St. Vrain Basin to better understand 

requirements for common shiner persistence.

Hornyhead chub (Nocomis biguttatus) was historically 

reported from Boulder and St. Vrain Creeks in the early 1900s 

(Juday, 1905). No other collections of this species have been 

made in Colorado since the early records of Juday (Ellis, 

1914; Hendricks, 1950; Li, 1968; Propst, 1982; Nesler and 

others, 1997). Hornyhead chub builds a mound of clean gravel 

in which to spawn (Cross and Collins, 1995). Several other 

species have been observed using chub mounds as spawning 

sites (Pflieger, 1997). Diet primarily consists of insects (Cross 

and Collins, 1995). Hornyhead chub is considered extirpated 

from Colorado (Nesler and others, 1997) and has noticeably 

declined in Wyoming where it was historically common in 

the Laramie River system (Baxter and Stone, 1995). Populations have also disappeared from western Kansas (Cross and 

Collins, 1995), where it is state listed as threatened (Schmidt, 

2006), and from the prairie portion of some Missouri streams 

(Pflieger, 1997). Additionally, hornyhead chub is a species 

of concern in North Dakota, Pennsylvania, and Manitoba 

(Schmidt, 2006).

Bigmouth shiner (Notropis dorsalis) inhabits the lower 

portions of the South Platte River and its major tributaries 

(Propst, 1982). Its distribution is patchy owing to specific 

habitat requirements such as sand and gravel-bottomed runs 

and riffles. This species appears to be intolerant of nutrient 

enrichment (Propst, 1982) and feeds on both invertebrates 

and filamentous algae (Schrader, 1989 and citations within). 

Although it is uncertain, bigmouth shiner is thought to spawn 

in open water as some other members of the genus where 

semi-buoyant eggs hatch as they drift downstream (Moore, 

1944). In the CDOW fish database, bigmouth shiner was 

present in collections from the 1960s to the 1990s in lower 

St. Vrain Creek. In the 1960s, 1970s, and 1980s, bigmouth 

shiner was collected from stations both up and downstream 

from the WWTP (segments 1, 2, and 3). Since 1990, it has 

only been collected one time out of eight sampling events at 

a station near Highway 287 (segment 2) and was not present 

in any of three sampling events downstream from the WWTP 

(CDOW fish database). Similar patterns in bigmouth shiner 

absence from previous collection locations have been observed 

in the Big Thompson and Cache la Poudre Rivers since the 

1980s (Kevin Bestgen, Larval Fish Laboratory, Colorado State 

University, oral commun., 2006). More effort is warranted to 

   Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
better understand bigmouth shiner distribution and abundance 

in St. Vrain Creek. Bigmouth shiner is listed as a species of 

concern in Indiana, Tennessee, and Manitoba, and is considered threatened in Pennsylvania (Schmidt, 2006).

Juday (1905) first reported blacknose shiner (Notropis 

heterolepis) in Colorado from St. Vrain Creek in Longmont. 

Propst (1982) believed the records to be authentic; however, 

this species has never been recollected in Colorado and 

consequently is considered extirpated from the State (Nesler 

and others, 1997). Additionally, blacknose shiner has been 

extirpated from Kansas (Cross and Collins, 1995) and from 

several streams in Missouri (Pflieger, 1997). Diet primarily 

consists of insects and small crustaceans (Becker, 1983), and 

spawning requirements are currently unknown. Additionally, 

this species is endangered in Illinois, Nevada, Ohio, and South 

Dakota, threatened in Iowa, and is a species of concern in 

North Dakota (Schmidt, 2006).

Sand shiner (Notropis stramineus) is commonly collected 

from the South Platte River and its major tributaries, where 

it often comprises a large portion of the sample when present 

(Propst, 1982). It inhabits a wide array of habitat types; however, it apparently avoids high-velocity riffles and deep pools. 

Although this species has been collected from areas with a 

variety of environmental conditions, it apparently is intolerant 

of heavy organic enrichment and silt-laden irrigation-return 

waters (Propst, 1982). Sand shiner feeds primarily on aquatic 

insects (Schrader, 1989 and citations within) and spawns over 

clean gravel in Missouri (Pflieger, 1997). Very little additional 

information is available regarding the details of spawning 

behavior. It is likely this species has somewhat flexible spawning requirements, as it is a common constituent of many plains 

streams in Colorado. In the plains portion of St. Vrain Creek, 

sand shiner has been routinely collected both upstream and 

downstream from the WWTP in all segments (CDOW fish 

database).

Historically, suckermouth minnow (Phenacobius mirabilis) was widespread in foothills and plains streams of 

the South Platte River Basin (Bestgen and others, 2003). 

Currently, in the South Platte River Basin, it is apparently 

restricted to the lower reaches (Bestgen and others, 2003; 

Nesler and others, 1997). Propst (1982) found this species 

associated with shallow side channels with sand and gravel 

riffles and suggested they are sensitive to siltation and nutrient enrichment. Bestgen and others (2003) found deep pools 

below diversion dams to be important features for suckermouth minnow during drought in the South Platte River Basin. 

Like Propst, Bestgen and others (2003) typically collected 

suckermouth minnow over gravel. They feed primarily on 

aquatic insects, but are known to consume plant material and 

bottom ooze (Schrader, 1989 and citations within). The first 

reported records of suckermouth minnow in St. Vrain Creek 

are from Juday (1905). Subsequently, this species has not been 

recollected in the St. Vrain system (Nesler and others, 1997) 

although St. Vrain Creek was not intensively sampled during a recent investigation of factors influencing suckermouth 

minnow distribution (Bestgen and others, 2003). Suckermouth 

minnow is currently listed as state endangered in Colorado 

and Mississippi, threatened in New Mexico, and is a species of 

concern in Arkansas, Louisiana, South Dakota, West Virginia, 

and Wyoming (Nesler and others, 1997; Schmidt, 2006). More 

effort is needed to identify suckermouth minnow distribution 

in St. Vrain Creek downstream from the WWTP.

Northern redbelly dace (Phoxinus eos) is rare in Colorado, both historically and at present (Nesler and others, 

1997). Bestgen (1989) documented the distribution of this 

species and provided notes on its biology in Colorado. In 

the South Platte River system, this species was present in 

Boulder and St. Vrain Creeks. It is currently only present in 

Colorado in the Upper South Platte tributary of West Plum 

Creek 50 miles southwest of Denver (Bestgen, 1989). All 

recent records of this species in Colorado are from transition 

zone, standing-water habitats (Bestgen, 1989), and historical 

records reported by Ellis (1914) were all from transition-zone 

stream habitats in West Plum Creek, Boulder Creek, and 

St. Vrain Creek. Despite extensive sampling, this species was 

not collected from stream habitats but rather from cool, clear, 

standing water habitats off the main channel in the West Plum 

Creek area (Bestgen, 1989). Bestgen (1989) noted that these 

standing-water habitats were associated with cool springs 

or diverted cool-stream flow. In West Plum Creek, northern 

redbelly dace diet includes mostly detritus; however, they also 

consume plant material, algae, and zooplankton (Bestgen, 

1989). Spawning apparently occurs in mats of filamentous 

algae (Becker, 1983). Reductions of this species in streams 

are presumed to be a result of the destruction of associated 

off-channel habitats by stream channelization, reductions in 

discharge, and poor water quality (Bestgen, 1989). Interestingly, a hybrid specimen (P. eos x finescale dace [P. neogaeus]) was collected from St. Vrain Creek in 1986 upstream 

from the WWTP (Bestgen, 1989). Although finescale dace 

has never been collected in the South Platte River Basin, 

hybrids are maintained by gynogenesis where the hybrid dace 

are female clones (Dawley and others, 1987; Bestgen, 1989). 

In gynogenesis, genetic material is not incorporated into the 

offspring even though the sperm from the male is needed to 

stimulate egg development. Some female hybrid dace can even 

reproduce by cloning (Goddard and others, 1998). Schlosser 

and others (1998) reported entire populations with the same 

genes in Minnesota. Northern redbelly dace is currently state 

listed as endangered in Colorado, Massachusetts, threatened in 

Nebraska and South Dakota, and of concern in North Dakota 

(Nesler and others, 1997; Schmidt, 2006). Montana listed 

hybrid populations as species of special concern (Hunter, 

1997). Protected off-channel habitats will likely be needed in 

the St. Vrain Creek Basin to reestablish populations. Recently, 

individuals were stocked in the St. Vrain Creek Basin in two 

small off-channel habitats on City of Boulder and Boulder 

County Open Space property (Harry Crockett, Colorado 

Division of Wildlife, oral commun., 2006). It is unknown to 

what extent instream habitat typical of northern redbelly dace 

has changed in the St. Vrain Creek and Boulder Creek Basins 

since early collections.

Approach and Results 
Fathead minnow (Pimephales promelas) is one of the 

most frequently encountered species in the South Platte River 

Basin (Nesler and others, 1997) and can tolerate a wide variety 

of environmental conditions (Propst, 1982; Pflieger, 1997). 

Although it can make use of a variety of habitats, it is most 

frequently found in stream reaches with numerous pools and 

velocities below a few centimeters per second (Propst, 1982). 

Diets are composed primarily of algae and higher plant material; however, they also consume aquatic insects (Schrader, 

1989 and citations within). Eggs are deposited on submerged 

objects such as rocks, boards, or tree roots during spawning 

(Markus, 1934). In the plains portion of St. Vrain Creek, they 

are often the most frequently encountered minnow present 

in samples both above and below the WWTP (CDOW fish 

database).

Longnose dace (Rhinichthys cataractae) is typically associated with foothill and transition-zone streams of the South 

Platte River Basin, inhabiting riffles with rubble substrate 

having moderate to fast velocity (Propst, 1982). Its abundance 

typically decreases as riffle habitat becomes less common. 

Longnose dace can tolerate a wide variety of environmental 

conditions, even heavy organic enrichment and heavily urbanized areas. Food items include mostly aquatic insects and 

small amounts of algae (Schrader, 1989 and citations within). 

Breeding habits have not been studied in the Rocky Mountain 

region (Baxter and Stone, 1995). Longnose dace also persists 

in low numbers in the main stem of the South Platte River 

in eastern Colorado (Propst, 1982). In the plains portion of 

St. Vrain Creek, longnose dace has been consistently collected 

upstream and downstream from the WWTP (CDOW fish data 

base).

Creek chub (Semotilus atromaculatus) is considered common in the South Platte River Basin (Propst, 1982; Nesler and 

others, 1997). This species can be found in all habitat types, 

including environmentally degraded locations; however, it prefers sites with a high degree of habitat diversity (Propst, 1982). 

Creek chub inhabits a variety of habitats including shallow 

backwaters, undercut banks retained by root systems, and deep 

pools. Creek chub are generalists, feeding on aquatic insects 

and small fishes; however, their diets shift depending on what 

is available (Schrader, 1989 and citations within). It is usually associated with flowing streams with gravel substrate for 

spawning but is more tolerant of silt than other gravel spawning fishes (Baxter and Stone, 1995). In St. Vrain Creek, creek 

chub is a common constituent of collections both upstream 

and downstream from the WWTP (CDOW fish database).

Suckers (Catostomidae)

Longnose sucker (Catostomus catostomus) is considered 

a common cool-water transition zone species (Nesler and 

others, 1997). It inhabits a variety of habitats, and is often collected from high velocity riffles, undercut banks, and shaded 

pools (Propst, 1982). It is usually absent from sites void of riffles or runs and is absent from intermittent streams. Longnose 

sucker is an opportunistic feeder, taking advantage of both 

plants and invertebrates (Schrader, 1989 and citations within). 

Prior to 1980, it was commonly collected in low numbers in 

the main stem of the South Platte River as far east as Julesburg 

(CDOW fish database). Juday (1905) reported the first known 

collections of longnose sucker from St. Vrain Creek, presumably collected near Highway 287 (segment 2). This species 

continues to be collected in all segments of the study reach.

White sucker (Catostomus commersoni) is a very prevalent species in the South Platte River Basin and can tolerate a 

wide variety of environmental conditions (Propst, 1982). Large 

white suckers (greater than 6 inches in total length) are usually 

found in deep pools and slow moving runs; small white suckers (less than 6 inches in total length) inhabit shallow backwater, riffles of moderate velocity, and sand-rubble runs. 

White suckers consume a wide range of food items including 

insects, plant material, fish, and fish eggs (Schrader, 1989 and 

citations within). Juday (1905) collected the earliest records of 

white sucker from St. Vrain Creek at a site presumably near 

Highway 287 (segment 2). Since that time, this species continues to be present in collections throughout the plains portion 

of St. Vrain Creek (CDOW fish database).

Bullhead Catfishes (Ictaluridae)

Black bullhead (Ictalurus melas) typically occurs in low 

numbers in plains streams and can tolerate a wide range of 

water-quality conditions (Nesler and others, 1997). Propst 

(1982) reported it from several “widely scattered locations” in 

the South Platte River Basin. When found, it often inhabits silt 

and sand-bottomed backwater pools or sloughs associated with 

gravel bars, bridge abutments, or debris piles (Propst, 1982). 

Immature individuals often eat crustaceans, and adults feed on 

large cladocerans, midge pupae, and other immature aquatic 

insects (Repsys and others, 1976). They often spawn in cavities in logs or undercut banks, but no overhead cover is necessary for spawning success (Pflieger, 1997). In St. Vrain Creek, 

black bullhead is occasionally collected from sites above and 

below the WWTP (CDOW fish database). Nocturnal habits 

likely make this species less susceptible to daytime sampling, 

which may help explain why they are infrequently collected.

Channel catfish (Ictalurus punctatus) has never been 

common in moving water habitats of the South Platte River 

Basin (Ellis, 1914; Li, 1968; Propst, 1982). Populations are 

primarily managed by stocking in reservoirs for sport fishing (Nesler and others, 1997). This species occasionally is 

collected from St. Vrain Creek both above and below the 

WWTP (CDOW fish database). The occurrence of this species 

in St. Vrain Creek is likely a result of escapes from adjacent 

abandoned gravel pits and reservoirs managed for fishing.

Stonecat (Noturus flavus) is considered rare in Colorado, 

having only been collected from the St. Vrain and Republican River Basins (Nesler and others, 1997). Cockerell (1908) 

reported stonecat from Colorado but did not provide location 

information. Beckman (1952) reported it from the Republican River near the Colorado-Nebraska border; however, 

specimens are not available for verification of these early 

 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
reports. Cancalosi (1981) confirmed the presence of stonecat 

in the Republican River. No specimens were reported by 

Propst (1982) during an extensive inventory of the South 

Platte River Basin. Later, Platania and others (1986) collected stonecat from St. Vrain Creek at a site just upstream 

from the WWTP (segment 2). In Missouri, stonecat inhabits 

shallow riffles or runs with noticeable current and available 

cover and is apparently absent from high-velocity streams 

(Pflieger, 1997). Similar habitat requirements are described 

by Cross and Collins (1995) in Kansas. Platania (1986) 

reported St. Vrain Creek specimens being collected from a 

variety of habitats with available cover including “undercut 

banks” and a “shallow, unvegetated, rubble-substrate pool.” 

Diet mainly consists of aquatic insects, but they also feed on 

minnows, crayfish, mollusks, and plant material (Schrader, 

1989 and citations within). Large specimens occasionally eat 

other fish. Eggs are typically deposited under flat stones and 

guarded by the male. This species is likely more common than 

records indicate because of its nocturnal habits and preference 

for cover that make it less susceptible to daytime sampling 

(Nesler and others, 1997). Cross and Collins (1995) reported 

declines in stonecat distribution in western Kansas. Stonecat 

is endangered in North Carolina and Vermont and is a species 

of concern in Arkansas, Massachusetts, Oklahoma, Virginia, 

and Saskatchewan (Nesler and others, 1997; Schmidt, 2006). 

Additionally, stonecat is a species of concern in Colorado due 

to its limited distribution. The historic distribution, present 

abundance, and specific habitat requirements of stonecat in 

Colorado is unclear.

Killifishes (Fundulidae)

Plains topminnow (Fundulus sciadicus) is considered 

uncommon in the South Platte River Basin (Nesler and others, 

1997). When collected, it is found almost exclusively at sites 

with aquatic vegetation, almost stagnant water, and gravel 

substrate (Propst, 1982). Diet is not well studied; however, 

insects are thought to be an important component (Pflieger, 

1997; Cross and Collins, 1995). Eggs are deposited among 

plants or algae. Collection of plains topminnow from St. Vrain 

Creek has been rare (CDOW fish database). Juday (1905) first 

reported the species from the St. Vrain and Boulder Creeks. 

Ellis (1914) later reported several individuals from similar 

sites in the St. Vrain Creek Basin. Propst (1982) noted there 

was “no apparent geographic pattern to their distribution” and 

that they were “absent from many sites containing suitable 

habitat.” Plains topminnow was last collected from St. Vrain 

Creek in 2004 downstream from the WWTP; prior to 2004, 

it was collected sporadically at sites upstream (CDOW fish 

database). Lynch (1988) suggested competition with mosquito 

fish, a widely introduced species for mosquito control, to be 

a reason for plains topminnow declines in Nebraska. Others 

have linked native species declines to mosquito fish, as it is 

a known predator of other fish larvae (Meffe, 1985). Nesler 

and others (1997) and Patton (1997) suggested this is not the 

case in Colorado and Wyoming. Plains topminnow is a species 

of concern in Missouri, Minnesota, and Oklahoma, and is 

threatened in South Dakota (Nesler and others, 1997; Missouri 

Natural Heritage Program, 2006; Schmidt, 2006).

Plains killifish (Fundulus zebrinus) is a minor component of most moving water habitats, but is a very distinctive 

component of plains streams. It has been reported from foothill streams, but only from sites resembling plains locations 

(Propst and Carlson, 1986). Typically, plains killifish is found 

in shallow, stagnant, backwater habitats, and other protected 

areas with filamentous algae (Propst, 1982). They are opportunistic feeders with a preference for aquatic insects but also 

eat diatoms and other plant material. Eggs are deposited on 

sand and are unattended (Cross and Collins, 1995). The earliest records of this species from St. Vrain Creek are from the 

early 1900s (Juday, 1905); there are few additional records of 

plains killifish from St. Vrain Creek since that time (CDOW 

fish database). Bestgen (Larval Fish Laboratory, Colorado 

State University, oral commun., 2006) has noticed declines in 

killifish presence from previous collection locations in the Big 

Thompson and Cache la Poudre Rivers since the 1980s.

Livebearers (Poeciliidae)

Non-native western mosquito fish (Gambusia affinis) 

was not present in records before 1980 in the South Platte 

River Basin (CDOW fish database) and has not received much 

attention in the literature of the fishes of Colorado. This fish 

has been widely introduced as a means to control mosquitoes 

in Colorado (Woodling, 1985) and others parts of the United 

States and the World. This species is susceptible to cold 

temperatures and typically does not survive winters in Colorado, although a few over-wintering populations have been 

found in Denver and other parts of the State (Woodling, 1985). 

Diet consists of aquatic insects as well as fish larvae. Young 

are born live and fully active, repeatedly, during the summer 

(Cross and Collins, 1995). Western mosquito fish can inhabit 

nearly all still-water habitats associated with plains streams, 

from slow-moving pools to isolated, stagnant overflow areas. 

The influence of this species on native fish requiring similar habitat such as plains killifish and plains topminnow is 

unknown in Colorado. In Nebraska, Lynch (1988) suggested 

competition with mosquito fish to be a reason for plains topminnow declines. Others have found mosquito fish to consume 

other fish larvae (Meffe, 1985). The influence of mosquito 

fish on morphologically similar native species such as plains 

topminnow and plains killifish in Colorado is unknown.

Sticklebacks (Gasterosteidae)

Propst and Carlson (1986) describe brook stickleback 

(Culaea inconstans) as a minor component of plains streams 

and as having a “patchy” distribution in the South Platte River 

Basin. Propst (1982) considered brook stickleback as native, 

although this species was not recorded in early surveys. This 

species seems to prefer undercut banks and backwater habitats 

with vascular macrophytes or filamentous algae (Propst, 

1982). Diet includes algae, aquatic insect larvae, and small 

Approach and Results 
crustaceans (Schrader, 1989 and citations within). Nests are 

constructed in shallow water (Woodling, 1985). This species 

occasionally is collected from St. Vrain Creek at locations just 

upstream from the WWTP (segment 2). Brook stickleback is a 

species of concern in Pennsylvania (Schmidt, 2006).

Sunfishes (Centrarchidae)

Several non-native sunfish species, including but not 

limited to bluegill (Lepomis macrochirus), largemouth bass 

(Micropterus salmoides), and black crappie (Pomoxis nigromaculatus), have been introduced into reservoirs and gravel 

pits throughout the plains portion of the St. Vrain River Basin 

and other parts of Colorado for sport-fishing opportunities. 

These species never make up a large portion of samples in 

plains streams in terms of their abundance, nor do they appear 

to reproduce in these habitats in Colorado. These non-native 

species have been collected periodically from all segments of 

the plains portion of St. Vrain Creek (CDOW fish database). 

The influence of these non-native predators on native fishes is 

currently unknown.

Green sunfish (Lepomis cyanellus) is commonly found 

in permanent streams of the plains portion of the South Platte 

River Basin and in lower portions of South Platte tributaries, 

but they are never collected in large numbers (Propst, 1982). 

This species inhabits locations with moderate nutrient enrichment and a variety of physical and chemical conditions; however, Propst (1982) reported it only from sites that had either 

deep, vegetated potholes or structured banks and large pools. 

Adult green sunfish consume fish, including younger green 

sunfish, insects, and crayfish (Schrader, 1989 and citations 

within). Males build nests and guard their young. Juday (1905) 

reported the first records of green sunfish from the plains portion of St. Vrain Creek. This species has been and continues to 

be consistently collected at sites upstream from Highway 287 

(segments 1 and 2); however, the occurrence of this species 

downstream from Highway 287 (segment 3) appears to be 

sporadic, only being reported on a few occasions (CDOW fish 

database).

Orangespotted sunfish (Lepomis humilis) is considered 

rare in the South Platte River Basin (Nesler and others, 1997) 

and has been collected occasionally from sites in the plains 

portion of St. Vrain Creek. This species prefers habitat similar 

to green sunfish, such as deep, slow-velocity pools with cover 

(Propst, 1982). Propst further reports the association of this 

species with pools containing root systems of large cottonwoods. Their primary food includes insects and crustaceans 

with occasional occurrences of fish scales, algae, and small 

fish (Schrader, 1989 and citations within). Males build nests 

and guard their young. Juday (1905) first reported orangespotted sunfish from a site presumably near Highway 287 

(segment 2) in St. Vrain Creek. This species has also been collected above Hover Road in segment 1 (CDOW fish database).

Perches (Percidae)

Iowa darter (Etheostoma exile) exists in low numbers 

in the South Platte River Basin even though populations are 

considered stable in Colorado (Nesler and others, 1997). It 

inhabits cool clear streams with sand substrates and is found in 

cool off-channel environments with rooted vegetation (Woodling, 1985; Nesler and others, 1997). Propst (1982) found Iowa 

darter associated with undercut stream banks with vegetative cover. Diet mostly consists of amphipods, copepods, and 

aquatic insects (Schrader, 1989 and citations within). Little is 

known about the life history of Iowa darter in Colorado. Iowa 

darter is occasionally collected from St. Vrain Creek at sites 

just upstream from the WWTP (CDOW fish database). This 

species is listed as a species of special concern in Colorado 

because of its apparent specialized habitat requirements that 

occurs in areas of Colorado that are under rapid urban development (Nesler and others, 1997). Iowa darter also is a species 

of concern in Ohio and Vermont and is endangered in Illinois 

(Nesler and others, 1997; Schmidt, 2006).

Johnny darter (Etheostoma nigrum) inhabits foothill 

streams of the South Platte River Basin, where it was once 

considered common by early workers (Jordon, 1891; Juday, 

1905; Ellis, 1914). Since that time its abundance and distribution have generally declined (Propst and Carlson, 1989). The 

Johnny darter prefers shallow, slow-to-moderate velocity runs 

with cobble bottoms and shallow backwater. Propst (1982) 

reported this species to be absent from silt-laden-stream 

reaches below irrigation return flows and noticed the absence 

of Johnny darter when large numbers of crayfish were present. 

In Colorado, diet consists largely of midge larvae, and eggs are 

deposited on the undersides of smooth, elevated cobble (Propst 

and Carlson, 1989). Johnny darter has been consistently collected in low numbers from St. Vrain Creek above and below 

the WWTP (CDOW fish database). A better understanding 

of the current distribution and abundance of Johnny darter 

in St. Vrain Creek would allow comparison with collections 

made by Propst and Carlson (1989) to help better understand 

population dynamics of this species.

Non-native yellow perch (Perca flavescens) are introduced into abandoned gravel pits and reservoirs in the plains 

portion of St. Vrain Creek for recreational opportunities. 

They have been occasionally collected in St. Vrain Creek at 

locations near reservoirs where they have been stocked (segments 1 and 3). The influence of yellow perch on native plains 

fish communities is unknown.

Macroinvertebrate Communities

Very few collections were made of aquatic invertebrates 

in the plains portion of the South Platte River Basin prior 

to the advent of the Clean Water Act in the early 1970s. As 

a result, very little is known about the aquatic invertebrate 

10 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
fauna that historically occurred in St. Vrain Creek or any other 

plains streams in Colorado. There are sporadic early records 

of macroinvertebrates from other plains streams where several 

species have not been recollected (Edmunds and McCafferty, 

1984; McCafferty and others, 1993; Kondratieff and Baumann, 

2002). Needham and Claassen (1925) first reported the stonefly Isoperla bilineata, a species commonly found in Eastern 

and Midwestern states, in Colorado, but did not give locality 

information. Needham and Claassen deposited much of their 

material in the Entomological Collection at Cornell University, 

Ithaca, N.Y.; however, these specimens could not be located 

during a recent study (Zuellig and others, 2006). Other stonefly species historically known from transition-zone streams but 

that have not been recollected include Isogenoides elongatus 

and Taenionema pacificum (Kondratieff and Baumann, 2002), 

which were collected in the late 1800s. Other stonefly records 

collected in the 1940s from the South Platte River at Littleton 

include the stoneflies Capnia decepta and Capnia vernalis

(Illinois Natural History Survey, catalogue numbers, 12103 

and 1376), which also have not been recollected at these localities. Additionally, there are early records (late 1800s early 

1900s) of the mayflies McDunnough persimplex and Ephemera compar from transition zone streams that have never been 

recollected since that time (McCafferty and others, 1993). 

Ephemera compar is considered an extinct mayfly, as it was 

only known from the early collection from “Denver Foothills” 

(McCafferty, 2001). Furthermore, Herrmann and others (1986) 

reviewed the caddisflies of Colorado and reported on several 

species from early collections where locality information was 

vague. They considered these records unreliable because the 

original specimens could not be verified or additional material 

was never recollected despite extensive effort.

There is at least partial evidence of changes in macroinvertebrate species distributions in St. Vrain Creek based 

on the historic record. The earliest records presumed to be 

from St. Vrain Creek were collected in 1938, well after many 

modifications had already occurred to Front Range streams. 

One adult stonefly specimen of Perlesta decipiens, a common Midwestern species, resides in the INHS collection. 

Locality information associated with this single specimen is 

“Longmont.” Although the specific locality is unknown, it was 

most likely collected from St. Vrain Creek somewhere near 

the present day Highway 287, just upstream from the WWTP 

(segment 2). This species appears to be common in the eastern 

portion of the South Platte River Basin and is occasionally collected near the plains mountain interface (Zuellig and others, 

2006). Although this species is collected from other plains 

South Platte River Basin localities, it has not been collected 

from St. Vrain Creek since 1938. It is unknown if this species 

has been extirpated from St. Vrain Creek.

There are a few more recent examples of macroinvertebrate community change in St. Vrain Creek. Ward (1986) 

published an extensive study describing macroinvertebrate altitudinal zonation patterns in St. Vrain Creek, but unfortunately 

sampled only one site on the plains, located approximately 

6 miles downstream from the town of Lyons (probably near 

Hygiene Road). In this study, Ward reported several species of 

mayflies (Diphetor hageni, Pseudocloeon dardanum, Epeorus 

albertae, Nixie spp., Heptagenia elegantula, Rhithrogena 

hageni, Choroterpes inornata, Paraleptophlebia heteronea, 

Ephemerella dorothea infrequens, Attenella margarita, and 

Serratella micheneri), stoneflies (Isoperla quinquepunctata, 

Skwala americana, Claassenia sabulosa, Triznaka signata), 

and caddisflies (Glossosoma sp., Nectopsyche sp., and 

Limnephilus sp.) that have not been found during any of the 

sampling conducted by the City of Longmont from 2000 to 

2006. Because most of the City of Longmont macroinvertebrate samples were identified to the family level, it is uncertain 

which species may have been eliminated, although some information can be inferred. Recent samples collected during this 

study also did not include any of the above mentioned genera. 

Further effort is warranted to determine if these observations 

are real or a result of small differences in site locations.

Biological Data Synopsis

At least 33 fish species have been collected from 

St. Vrain Creek in the study reach since the earliest records of 

Juday. Twenty-five of these 33 species are considered native to 

the South Platte River Basin; the remaining 8 are non-native. 

Of the 25 native species, 2 species (hornyhead chub and 

blacknose shiner) are considered extirpated from Colorado and 

8 (northern redbelly dace, suckermouth minnow, lake chub, 

brassy minnow, common shiner, stonecat, Iowa darter, and 

orangespotted sunfish) are state listed as threatened, endangered, or species of concern; many are also species of concern 

in other states. Of the eight state listed species, three (northern 

redbelly dace, suckermouth minnow, and lake chub) have not 

been recollected from the study boundaries since their original 

early accounts. Of the remaining state listed species known 

from St. Vrain Creek, two (common shiner and stonecat) are 

frequently encountered and three are occasionally collected 

(brassy minnow, Iowa darter, and orangespotted sunfish). The 

remaining 15 native species include several that are commonly 

collected (sand shiner, red shiner, creek chub, fathead minnow, 

longnose dace, longnose sucker, white sucker, green sunfish) 

and others that are occasionally encountered in comparatively 

lower abundances (channel catfish, black bullhead, brook 

stickleback, plains killifish, bigmouth shiner, plains topminnow, and Johnny darter). Remarkably, the 10 state listed or 

extirpated species described above represent more than 40 percent of the total native fish fauna in the South Platte River 

Basin that are known from a short section of St. Vrain Creek.

Although much less is known about early macroinvertebrate community structure in St. Vrain Creek, there is evidence that macroinvertebrate communities have changed in 

other Front Range transitional zone streams. Several species 

of stoneflies, such as Isoperla bilineata, Isogenoides elongatus, Taenionema pacifica, Capnia decepta, Capnia vernalis, 

and the mayfly McDunnough persimplex have apparently 

been locally eliminated from other regional streams. Additionally, the mayfly Ephemera compar is considered extinct 

Approach and Results 11
and the stonefly Perlesta decipiens has not been recollected 

from St. Vrain Creek since 1938. Several species of mayflies, 

stoneflies, and caddisflies have been reported from a site 

presumably near Hygiene Road that have not been recorded by 

the city of Longmont in their samples collected since 2000 at a 

nearby downstream site.

St. Vrain Creek continues to harbor native fish species 

of concern that have declined in other parts of the South 

Platte River Basin. Generally, fish collections in the Colorado 

Division of Wildlife fish database and the City of Longmont 

macroinvertebrate samples from St. Vrain Creek have been 

collected inconsistently in space and time. Macroinvertebrate 

samples collected prior to 2005 by the City of Longmont were 

processed at the family level, making it difficult to determine 

community response to changing water-quality or habitat 

conditions. As a result, these data cannot be used to assess 

the influence of recent upgrades in WWTP operations. If 

biological data are used to assess the effects of future WWTP 

upgrades or habitat improvements in St. Vrain Creek, then a 

monitoring program designed to address specific questions 

will be necessary for a meaningful interpretation. Additionally, 

more effort is warranted to better understand the differences 

between macroinvertebrate collections made by Ward (1986) 

and by the City of Longmont and to better understand fish 

community dynamics in St. Vrain Creek. Furthermore, investigation is needed to understand if there are unique characteristics of St. Vrain Creek that allow the persistence of many fish 

species of concern in Colorado.

Wastewater Compounds

Wastewater samples were collected at the seven sites 

during the spring of 2005 and 2006. A Lagrangian-sampling 

design (following the same parcel of water as it moves downstream) was used during each sampling event, and time-oftravel studies were conducted just prior to each sampling event 

to determine appropriate sampling times.

Travel-Time Estimation

Tracer studies provide accurate travel-time estimates 

within a stream reach. Travel-time estimates from tracer studies may be used to predict the time of arrival and passage of a 

dissolved constituent accidentally released or spilled upstream. 

These estimates also may be used to characterize movement of 

constituents that may be released into a stream intentionally, as 

in the case of WWTP discharge. In this study, rhodamine-WT 

dye was used as a tracer. Rhodamine-WT dye acts as a solute 

and completely mixes with the stream, simulating movement 

and dispersion of water particles (Ruddy and Britton, 1989). 

Rhodamine-WT has a highly detectable fluorescence that is 

easily isolated from background fluorescence and is harmless at the low concentrations used in this study. Fluorometry 

is a widely accepted technique for tracer measurements, as it 

provides simple and accurate stream-tracer detection at low 

concentrations of rhodamine-WT dye (Wilson and others, 

1986).

Rhodamine-WT Injection and Sampling

Travel times in the study reach were estimated twice, 

once in April of 2005 and again in March of 2006. Sluginjection dye doses were prepared by mixing a predetermined 

amount of dye into a small volume of water. The mixed dye 

was poured rapidly into the center of the stream, and a quick 

rinse of the container removed any remaining dye. The amount 

of dye used for each injection was determined using the 

following equation (Kilpatrick, 1970):

V x Q L

v d C m = p





 



 − 3 4 10 4

0 93

.

.

(1)

where

Vd is the volume of rhodamine-WT dye;

Qm is the mean discharge of the reach, in cubic feet 

per second;

L is the reach length, in miles;

v is the mean stream velocity, in feet per second; and

Cp is the peak concentrations desired at the end of the 

reach, in micrograms per liter.

Mean velocities and discharges throughout the reach were 

measured several days prior to the tracer experiment.

Grab samples were collected from the center of the 

stream at each site. A part of each sample was measured onsite 

to determine the arrival of the leading edge, peak, and trailing 

edge of the dye plume. Samples were collected approximately 

every 15 minutes prior to the arrival of the leading edge and 

then every 5 minutes until 10 percent of the peak concentration was reached. Because fluorescence is temperature dependent, the remainder of each sample was measured again at a 

constant temperature in the USGS Colorado Water Science 

Center Laboratory in Lakewood. All dye measurements were 

made using either a Turner Model 10 bench fluorometer or a 

Turner Design-360 portable fluorometer. Travel times were 

defined as the elapsed time for the dye peak to travel between 

two monitoring sites.

In order to complete the tracer studies over the full study 

reach in a reasonable amount of time, the stream was divided 

into segments where individual injections occurred (two segments in 2005 and three segments in 2006). On April 5, 2005, 

the first injection site was at the intersection of Airport Road 

and St. Vrain Creek, where 80 milliliters of dye were injected. 

The movement of this dye was monitored at three downstream 

sites—M9, the intersection of Boston Avenue and St. Vrain 

Creek, and M8 (table 2). The second injection site was immediately upstream from the bridge at the intersection of South 

Pratt Parkway and St. Vrain Creek, where 200 milliliters of 

dye were injected. The movement of this dye was monitored 

at four downstream sites—M8, M6, the intersection of Weld 

County Road 1 and St. Vrain Creek, and M4 (table 2).

12 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
On March 14, 2006, the first injection site was at the 

intersection of Airport Road and St. Vrain Creek, where 

80 milliliters of dye were injected. The movement of this dye 

was monitored at three downstream sites—M9, the intersection of Boston Avenue and St. Vrain Creek, and the intersection of South Pratt Parkway and St. Vrain Creek (table 3). 

The second injection site was at the intersection of Boston 

Avenue and St. Vrain Creek, where 110 milliliters of dye were 

injected. The movement of this dye was monitored at three 

downstream sites—the intersection of South Pratt Parkway 

and St. Vrain Creek, M8, and M6 (table 3). The third injection site was immediately upstream from the bridge at the 

inter­section of North 119th Street and St. Vrain Creek, where 

200 milliliters of dye were injected. The movement of this dye 

was monitored at three downstream sites—M6, the intersection of Weld County Road 1 and St. Vrain Creek, and M4 

(table 3).

A rating curve of the logarithm of the travel-time 

estimates and the logarithm of the stream discharge measurements was developed to estimate travel times in the study 

reach at the slightly different stream discharges encountered 

during the subsequent synoptic sampling in 2005 and 2006. 

For the synoptic sampling in 2005, streamflow had increased 

slightly compared to the tracer study only between sites M6 

and M4, and the travel time between these two sites was 

adjusted. For the synoptic sampling in 2006, streamflow had 

decreased slightly compared to the tracer study only between 

sites M9 and M8, and the travel time between these two sites 

was adjusted.

Lagrangian Synoptic

Wastewater samples were collected using standardized 

depth- and width-integrating techniques and were processed 

and preserved onsite using standard methods described in 

U.S. Geological Survey (variously dated). Samples were 

analyzed at the USGS National Water Quality Laboratory in 

Denver, Colo., according to methods described in Zaugg and 

others (2002). Quality-control samples, including one field 

blank, one replicate, and one laboratory spike, were collected 

during each sampling event. In addition, field measurements 

were obtained for water temperature, dissolved oxygen, pH, 

specific conductance, and discharge at the time of sampling.

Samples were collected longitudinally in a Lagrangian 

manner at specific times calculated from the travel-time 

data. Lagrangian sampling follows the same parcel of water 

as it moves downstream. Sampling times were based on the 

stream velocity between sites; sampling occurred when it was 

estimated that the target parcel of water had reached each site. 

Sampling in this manner allows changes in chemical concentration due to instream processing, attenuation, and dilution 

to be isolated from changes in upstream loading over time. 

Results from the Lagrangian synoptic are presented in table 4.

Hydrophobic Organic Compounds

Six-inch SPMDs were deployed at six sites (not including O1) in spring of 2005 and 2006, for approximately 4 

weeks. To prevent the rhodamine-WT dye from interfering 

with the target chemicals, the SPMDs were deployed at least 

a week before or after the travel-time experiments. After 

retrieval, contaminant residues concentrated in the SPMDs 

were recovered and separated from the lipid by dialysis in 

iso-octane at Environmental Sampling Technologies, in St. 

Joseph, Mo., by using methods described in Huckins and 

others (1990). The U.S. Army Corp of Engineers Environmental Laboratory in Vicksburg, Miss., then used the dialysate 

in toxicity testing. This toxicity assay, the P450RGS test, 

provides a rapid screen for aryl hydrocarbon receptor (AhR) 

type compounds that include PCBs, PAHs, dioxins, and furans 

Table 2. Travel-time results for the April 5, 2005, tracer study, St. Vrain Creek.

[E, estimated]

Collection site

Distance 

from first 

injection 

point

(miles)

Cumulative travel time of dye cloud

(minutes)

Average velocity 

of peak between 

adjacent sites 

(miles per hour)

Discharge at 

site 

(cubic feet 

per second) Leading edge Peak Trailing edge

M9 0.7 40 90 180 0.47 42.0

Boston Avenue and St. Vrain Creek 2.45 200 250 410 .66 40.2

M8 4.19 355 435 625 .56 42.1

M6 4.98 435 500 540 .73 76.0

Weld County Road 1 and St. Vrain 

Creek 6.07 500 585 670 .77 E78.0

M4 9.37 630 735 940 1.32 140

Approach and Results 13
(Murk and others, 1996). All vertebrates produce detoxifying 

enzymes upon exposure to AhR compounds; the amount of 

enzymes produced is directly proportional to the concentration of the compounds. Quantifying one of these enzymes (the 

gene CYP1A1) serves as a measure of dioxin activity. The 

concentration of AhR compounds in the SPMD extract that 

induce CYP1A1 production will be expressed as the amount 

of dioxin, in toxic equivalents (TEQs), that would induce the 

same response.

Quality-control samples for the SPMDs, including two 

replicates, one dialysis blank, and one trip blank, were collected during each sampling period. During processing in 

the laboratory, dialysis blanks were collected to monitor for 

possible manufacturing and laboratory contamination. Trip 

blanks were collected in the field by exposing an SPMD to the 

air for the amount of time it took to remove an SPMD from 

the canister and place it in the stream, and then to remove 

the same SPMD from the stream and place it back into the 

canister. With the trip blank, however, the SPMD was left 

in the canister whereas the field-SPMDs were deployed in 

the stream. In this way, the trip blank mimicked exposure to 

airborne chemical contamination that field-deployed SPMDs 

experienced during deployment and retrieval.

In 2005, the only compound detected in the blank sample 

was phenol; in 2006, both methyl salicylate and naphthalene 

were detected in the blank sample (table 4). In many cases, 

the concentration in the blank sample was greater than the 

respective concentrations in the environmental samples. Concentrations in blank samples can be used to assess potential 

contamination made during field collection and (or) laboratory 

analysis. In 2005, the percent difference in the concentrations 

of the replicate samples ranged from 0 to 58; the maximum 

percent difference was in beta-stigmastanol (table 5). In 2006, 

the percent difference in the concentrations of the replicate 

Table 3. Travel-time results for the March 14, 2006, tracer study, St. Vrain Creek.

[E, estimated]

Collection site

Distance 

from first 

injection 

point

(miles)

Cumulative travel time of dye cloud

(minutes)

Average velocity 

of peak between 

adjacent sites 

(miles per hour)

Discharge at 

site

 (cubic feet 

per second) Leading edge Peak Trailing edge

M9 0.7 100 180 310 0.23 10.3

Boston Avenue and St. Vrain Creek 2.45 400 550 780 .28 11.8

South Pratt Parkway and St. Vrain 

Creek 3.1 550 780 1,090 .17 15.2

M8 4.19 910 1,005 1,150 .29 15.9

M6 4.98 950 1,050 1,250 1.05 E33.0

Weld County Road 1 and St. Vrain 

Creek 6.07 1,040 1,170 1,350 .55 34.0

M4 9.37 1,280 1,340 1,520 1.16 E90.0

samples ranged from 0 to 100 (with the 100 percent difference 

indicating that one value out of the replicate pair was censored 

and the other was not); the maximum percent difference was in 

naphthalene (table 5). These percent difference values can be 

used to characterize potential variability in reported concentrations of each compound. Spike recoveries in 2005 and 2006 

are shown in table 5. In 2005, percent recoveries of the spiked 

concentrations ranged from 40 to 172, with a mean of 89; in 

2006, percent recoveries ranged from 23 to 206, with a mean 

of 101. Percent recovery of spike concentrations can be used 

to characterize potential recovery of these compounds during 

field collection and laboratory analysis.

In 2005, one laboratory replicate out of three had a 

detection in the toxicity assay of the dialysis blank, indicating 

potential for low-level contamination from manufacturing or 

laboratory processing during dialysis (table 6). The value in 

the trip blank was slightly higher than in the dialysis blank, 

indicating that there may have been additional low-level atmospheric contamination. In 2006, there were no detections in the 

toxicity assay of the dialysis or trip blank. In 2005, the percent 

difference in the values of the replicate samples ranged from 

5 to 35; in 2006, they ranged from 1 to 13 (table 6).

Acknowledgments

The authors gratefully acknowledge all those who helped 

with field work, including Norm Spahr, Alan Duran, Bret 

Bruce, Jason Gurdak, Jeff Bails, and Carmia Fiechtner from 

the USGS and Mary Paterniti and Kathryn Marko from the 

City of Longmont. Additionally, comments provided by Harry 

Crockett and Nicole Vieira with the Colorado Division of 

Wildlife and Bill Battaglin and Bret Bruce with the USGS 

greatly improved the quality of this data series report.

14  Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 4. Data from the analysis of wastewater compounds and associated field properties.

[Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time

QC 

sample 

type

Barometric 

pressure, 

in millimeters 

of mercury

Dissolved 

oxygen, 

in milligrams 

per liter

pH, 

in standard 

units

Specific 

conductance, 

in microsiemens per 

centimeter 

at 25 degrees 

Celsius

Water 

temperature, 

in degrees 

Celsius

1,4-Dichlorobenzene 1-Methyl- naphthalene

P00025 P00300 P00400 P00095 P00010 P34572 P62054

Environmental samples

M9 401011105084701 4/14/2005 0720 -- 628 9.7 7.5 177 8.0 <0.5 <0.5

M8 400919105051501 4/14/2005 1300 -- 630 11.9 8.0 495 11.9 <.5 <.5

T11 400918105051601 4/14/2005 1305 -- 630 11.7 8.1 897 15.0 <.5 <.5

O1 400920105051001 4/14/2005 1320 -- 630 9.3 7.3 1,324 16.6 E.17 <.5

M6 400911105042500 4/14/2005 1350 -- 630 11.2 7.9 796 14.4 E.030 <.5

T8 400928105003401 4/14/2005 1730 -- 630 9.3 8.3 734 17.4 <.5 <.5

M4 400937105002901 4/14/2005 1810 -- 630 9.0 8.1 800 16.9 <.5 <.5

M9 401011105084701 3/28/2006 1900 -- 630 8.6 8.1 375 11.3 <.5 <.5

M8 400919105051501 3/29/2006 1045 -- 625 12.6 8.4 160 10.5 <.5 <.5

T11 400918105051601 3/29/2006 1100 -- 625 12.6 8.4 1,210 10.5 <.5 <.5

O1 400920105051001 3/29/2006 1115 -- 625 11.1 7.3 1,590 15.0 E.21 <.5

M6 400911105042500 3/29/2006 1145 -- 625 13.8 8.2 1,400 13.5 E.097 <.5

T8 400928105003401 3/29/2006 1740 -- 625 9.0 8.6 940 15.0 <.5 <.5

M4 400937105002901 3/29/2006 1810 -- 625 9.5 8.8 1,160 15.1 E.012 <.5

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank -- -- -- -- -- <0.5 <0.5

O1 400920105051001 4/14/2005 1321 replicate -- -- -- -- -- E.16 <.5

M4 400937105002901 4/14/2005 1812 spike -- -- -- -- -- E.63 .73M9 401011105084701 3/28/2006 1901 replicate -- -- -- -- -- <.5 <.5

M6 400911105042500 3/29/2006 1147 spike -- -- -- -- -- E.59 .70

T8 400928105003401 3/29/2006 1700 blank -- -- -- -- -- <.5 <.5

Approach and Results 15
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time

QC 

sample 

type

2,6-Dimethylnaphthalene 2-Methyl- naphthalene 

3-betaCoprostanol 

3-Methyl-1Hindole 

3-tert-Butyl-4-

hydroxyanisole 4-Cumylphenol 

P62055 P62056 P62057 P62058 P62059 P62060

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <2.0 <1.0 <5.0 <1.0M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <2.0 <1.0 <5.0 <1.0

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <2.0 <1.0 <5.0 <1.0

O1 400920105051001 4/14/2005 1320 -- <.5 <.5 E1.00 E.058 E.10 <1.0

M6 400911105042500 4/14/2005 1350 -- <.5 <.5 E.33 <1.0 <5.0 <1.0

T8 400928105003401 4/14/2005 1730 -- <.5 <.5 E.44 <1.0 <5.0 <1.0

M4 400937105002901 4/14/2005 1810 -- <.5 <.5 E.28 E.028 <5.0 <1.0

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <2 <1.0 <5.0 <1.0

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 E.35 <1.0 <5.0 <1.0

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <2 <1.0 <5.0 <1.0

O1 400920105051001 3/29/2006 1115 -- <.5 <.5 E1.23 E.027 E.12 <1.0

M6 400911105042500 3/29/2006 1145 -- <.5 <.5 E.80 E.013 E.074 <1.0

T8 400928105003401 3/29/2006 1740 -- <.5 <.5 E.65 <1.0 <5.0 <1.0

M4 400937105002901 3/29/2006 1810 -- <.5 <.5 E.69 <1.0 <5.0 <1.0

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <2.0 <1.0 <5.0 <1.0

O1 400920105051001 4/14/2005 1321 replicate <.5 <.5 E.82 E.042 E.10 <1.0

M4 400937105002901 4/14/2005 1812 spike .72 .7 2.2 E.76 E.51 E.71

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <2 <1.0 <5.0 <1.0

M6 400911105042500 3/29/2006 1147 spike .75 .69 E3.29 E.86 E.98 1.06

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <2 <1.0 <5.0 <1.0

16 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time

QC 

sample 

type

4-Octylphenol 4-Nonyl- phenol 4-tert- Octylphenol 5-Methyl-1H- benzotriazole 9,10-Anthra- quinone Aceto- phenone 

Acetyl 

hexamethyl 

tetrahydronaphthalene

P62061 P62085 P62062 P62063 P62066 P62064 P62065

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <1.0 <5.0 <1.0 <2.0 <0.5 <0.5 <0.5

M8 400919105051501 4/14/2005 1300 -- <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

T11 400918105051601 4/14/2005 1305 -- <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

O1 400920105051001 4/14/2005 1320 -- <1.0 E1.10 <1.0 E1.50 <.5 E.12 E.360

M6 400911105042500 4/14/2005 1350 -- <1.0 E.41 <1.0 E.68 <.5 <.5 E.066

T8 400928105003401 4/14/2005 1730 -- <1.0 E.44 <1.0 <2.0 <.5 <.5 E.040

M4 400937105002901 4/14/2005 1810 -- <1.0 E.49 <1.0 E.64 <.5 <.5 E.046

M9 401011105084701 3/28/2006 1900 -- <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

M8 400919105051501 3/29/2006 1045 -- <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

T11 400918105051601 3/29/2006 1100 -- <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

O1 400920105051001 3/29/2006 1115 -- <1.0 E2.27 E.19 E1.53 <.5 E.21 E.45

M6 400911105042500 3/29/2006 1145 -- <1.0 E1.82 E.10 E1.18 <.5 E.12 E.24

T8 400928105003401 3/29/2006 1740 -- <1.0 <5.0 E.088 E.83 <.5 <.5 <.5

M4 400937105002901 3/29/2006 1810 -- <1.0 E.64 E.073 E.71 <.5 <.5 E.072

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <1.0 <5.0 <1.0 <2.0 <0.5 <0.5 <0.5

O1 400920105051001 4/14/2005 1321 replicate <1.0 E1.00 <1.0 E1.40 .5 E.12 E.320

M4 400937105002901 4/14/2005 1812 spike E.69 E5.60 E.81 4.7 .8 .88 .78M9 401011105084701 3/28/2006 1901 replicate <1.0 <5.0 <1.0 <2.0 .5 <.5 <.5

M6 400911105042500 3/29/2006 1147 spike E.75 E7.04 1.04 E7.29 .98 .98 1.11T8 400928105003401 3/29/2006 1700 blank <1.0 <5.0 <1.0 <2.0 <.5 <.5 <.5

Approach and Results 17
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time QC sample type Anthracene Benzo[a]pyrene Benzo- phenone beta- Sitosterol beta- Stigmastanol Bisphenol A Bromacil

P34221 P34248 P62067 P62068 P62086 P62069 P04029

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <0.5 <2.0 <2.0 <1.0 <0.5

M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <.5 <2.0 <2.0 <1.0 <.5

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <.5 <2.0 <2.0 <1.0 <.5

O1 400920105051001 4/14/2005 1320 -- <.5 <.5 E.200 E1.30 E 1.60 E.130 <.5

M6 400911105042500 4/14/2005 1350 -- <.5 <.5 E.036 <2.0 <2.0 <1.0 <.5

T8 400928105003401 4/14/2005 1730 -- <.5 <.5 <.5 E.66 <2.0 <1.0 <.5

M4 400937105002901 4/14/2005 1810 -- <.5 <.5 E.056 <2.0 E.29 <1.0 <.5

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <.5 <2.0 <2.0 E.20 <.5

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 <.5 <2.0 <2.0 E.24 <.5

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <.5 <2.0 <2.0 -- <.5

O1 400920105051001 3/29/2006 1115 -- <.5 <.5 E.19 E1.04 E.92 E.52 <.5

M6 400911105042500 3/29/2006 1145 -- <.5 <.5 E.10 E.52 <20 E.34 <.5

T8 400928105003401 3/29/2006 1740 -- <.5 <.5 E.077 E.60 E.61 E.26 <.5

M4 400937105002901 3/29/2006 1810 -- <.5 <.5 E.082 E.45 E.36 E.28 <.5

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <0.5 <2.0 <2.0 <1.0 <0.5

O1 400920105051001 4/14/2005 1321 replicate <.5 <.5 E.160 E.82 E.68 E.096 <.5

M4 400937105002901 4/14/2005 1812 spike .66 .54 .84 2.0 E1.70 E.810 3.4

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <.5 <2.0 <2.0 E.16 <.5

M6 400911105042500 3/29/2006 1147 spike .77 E.48 1.08 E2.64 E2.41 E1.18 4.08

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <.5 <2.0 <2.0 -- <.5

18  Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site number USGS station number Date (month/ day/year) Time QC sample type Caffeine Camphor Carbaryl Carbazole Chlorpyrifos Cholesterol Cotinine P50305 P62070 P82680 P62071 P38933 P62072 P62005

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <1.0 <0.5 <0.5 <2.0 <1.0

M8 400919105051501 4/14/2005 1300 -- E.058 <.5 <1.0 <.5 <.5 <2.0 <1.0

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <1.0 <.5 <.5 <2.0 <1.0

O1 400920105051001 4/14/2005 1320 -- 0.74 E.036 <1.0 <.5 <.5 2.2 E.33

M6 400911105042500 4/14/2005 1350 -- E.200 <.5 <1.0 <.5 <.5 E.62 <1.0

T8 400928105003401 4/14/2005 1730 -- E.180 <.5 <1.0 <.5 <.5 E.91 <1.0

M4 400937105002901 4/14/2005 1810 -- E.170 <.5 <1.0 <.5 <.5 E.72 <1.0

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <1.0 <.5 <.5 <2.0 <1.0

M8 400919105051501 3/29/2006 1045 -- E.079 <.5 <1.0 <.5 <.5 E.56 <1.0

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <1.0 <.5 <.5 <2.0 <1.0

O1 400920105051001 3/29/2006 1115 -- .58 E.057 <1.0 <.5 <.5 E2.45 E.14

M6 400911105042500 3/29/2006 1145 -- E.32 E.040 <1.0 <.5 <.5 E1.49 E.080

T8 400928105003401 3/29/2006 1740 -- E.32 <.5 <1.0 <.5 <.5 E.88 <1.0

M4 400937105002901 3/29/2006 1810 -- E.28 E.020 <1.0 <.5 <.5 E1.05 <1.0

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <1.0 <0.5 <0.5 <2.0 <1.0

O1 400920105051001 4/14/2005 1321 replicate .62 E.039 <1.0 <.5 <.5 E1.70 E.31

M4 400937105002901 4/14/2005 1812 spike .89 .76 E1.00 .69 .75 2.5 2.8

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <1.0 <.5 <.5 <2 <1.0

M6 400911105042500 3/29/2006 1147 spike 1.17 .84 E.84 .82 .90 E3.87 E3.83

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <1.0 <.5 <.5 <2.0 <1.0

Approach and Results 19
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time

QC 

sample 

type

DEET Diazinon Diethoxy- nonylphenol Diethoxy- octylphenol d-Limonene Ethoxy- octylphenol Fluoranthene

P62082 P39572 P62083 P61705 P62073 P61706 P34377

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <5.0 <1.0 <0.5 <1.0 <0.5M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

O1 400920105051001 4/14/2005 1320 -- E.37 <.5 E7.2 E.31 <.5 <1.0 <.5

M6 400911105042500 4/14/2005 1350 -- E.12 <.5 E1.6 <1.0 <.5 <1.0 <.5

T8 400928105003401 4/14/2005 1730 -- E.11 <.5 E1.7 E.18 <.5 E.23 <.5

M4 400937105002901 4/14/2005 1810 -- E.11 <.5 <5.0 E.10 <.5 E.16 <.5

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 E1.18 <1.0 <.5 <1.0 E.0086

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

O1 400920105051001 3/29/2006 1115 -- E.34 <.5 E12.4 E.84 <.5 E.33 <.5

M6 400911105042500 3/29/2006 1145 -- E.20 <.5 E6.81 E.44 <.5 E.22 <.5

T8 400928105003401 3/29/2006 1740 -- E.14 <.5 E2.89 E.25 <.5 E.34 <.5

M4 400937105002901 3/29/2006 1810 -- E.15 <.5 E2.68 E.24 <.5 E.22 <.5

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <5.0 <1.0 <0.5 <1.0 <0.5

O1 400920105051001 4/14/2005 1321 replicate E.37 <.5 E6.3 E.28 <.5 <1.0 <.5

M4 400937105002901 4/14/2005 1812 spike .81 .81 E 1.0 E.57 E.3900 E1.50 .69

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

M6 400911105042500 3/29/2006 1147 spike 1.20 .98 E20.0 E1.19 E.23 E2.30 .73

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <5.0 <1.0 <.5 <1.0 <.5

20 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time QC sample type

Hexahydrohexamethyl 

cyclopentabenzopyran Indole Isoborneol Isophorone Isopropyl- benzene Isoquino- line Menthol Metalaxyl

P62075 P62076 P62077 P34409 P62078 P62079 P62080 P50359

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

O1 400920105051001 4/14/2005 1320 -- 2.1 E.230 <.5 <.5 <.5 <.5 <.5 E.066

M6 400911105042500 4/14/2005 1350 -- E.43 E.036 <.5 <.5 <.5 <.5 <.5 <.5

T8 400928105003401 4/14/2005 1730 -- E.24 <.5 <.5 <.5 <.5 <.5 <.5 <.5

M4 400937105002901 4/14/2005 1810 -- E.28 <.5 <.5 <.5 <.5 <.5 <.5 <.5

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

T11 400918105051601 3/29/2006 1100 -- E.032 <.5 <.5 <.5 <.5 <.5 <.5 <.5

O1 400920105051001 3/29/2006 1115 -- 2.54 E.11 <.5 <.5 <.5 <.5 <.5 <.5

M6 400911105042500 3/29/2006 1145 -- 1.43 E.056 <.5 <.5 <.5 <.5 <.5 <.5

T8 400928105003401 3/29/2006 1740 -- E.34 E.036 <.5 <.5 <.5 <.5 <.5 <.5

M4 400937105002901 3/29/2006 1810 -- E.47 <.5 <.5 <.5 <.5 <.5 <.5 <.5

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

O1 400920105051001 4/14/2005 1321 replicate 2.1 E.200 <.5 <.5 <.5 <.5 <.5 E.067

M4 400937105002901 4/14/2005 1812 spike .99 .67 .8 .82 E.50 .79 .78 .8

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

M6 400911105042500 3/29/2006 1147 spike 2.33 .79 .86 .91 E.30 .92 .90 1.15

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <.5 <.5 <.5 <.5 <.5 <.5

Approach and Results 21
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time QC sample type

Methyl 

salicylate

Metolachlor Naphtha- lene p-Cresol Penta- chloro- phenol Phenan- threne Phenol Prometon

P62081 P39415 P34443 P62084 P34459 P34462 P34466 P04037

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <0.5 <1.0 -- <0.5 <0.5 <0.5

M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <.5 <1.0 -- <.5 E.14 <.5

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 E.027 <1.0 -- <.5 E.19 <.5

O1 400920105051001 4/14/2005 1320 -- <.5 <.5 E.022 1.4 -- <.5 0.87 <.5M6 400911105042500 4/14/2005 1350 -- <.5 <.5 E.022 E.26 -- <.5 E.25 <.5

T8 400928105003401 4/14/2005 1730 -- <.5 <.5 E.021 E.10 -- <.5 E.17 <.5

M4 400937105002901 4/14/2005 1810 -- <.5 <.5 E.026 E.12 -- <.5 .57 <.5M9 401011105084701 3/28/2006 1900 -- <.5 <.5 E.0085 <1.0 -- <.5 E.27 <.5

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 E.012 E.17 -- E.0092 <.5 <.5

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 E.014 <1.0 -- <.5 <.5 <.5

O1 400920105051001 3/29/2006 1115 -- <.5 <.5 <.5 E.88 -- <.5 .86 <.5

M6 400911105042500 3/29/2006 1145 -- <.5 <.5 E.011 E.24 -- E.013 E.24 <.5

T8 400928105003401 3/29/2006 1740 -- <.5 <.5 <.5 E.16 -- <.5 E.21 <.5

M4 400937105002901 3/29/2006 1810 -- <.5 <.5 <.5 E.22 -- <.5 E.32 <.5

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <0.5 <1.0 -- <0.5 E0.28 <0.5

O1 400920105051001 4/14/2005 1321 replicate <.5 <.5 E.024 1.5 -- <.5 .91 <.5

M4 400937105002901 4/14/2005 1812 spike .78 .75 .74 E.90 E3.5 .72 .89 .81

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <.5 <1.0 -- <.5 E.19 <.5

M6 400911105042500 3/29/2006 1147 spike .85 1.01 .69 1.03 E3.51 .75 1.04 1.01T8 400928105003401 3/29/2006 1700 blank E.017 <.5 E.011 <1.0 -- <.5 <.5 <.5

22 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site 

number

USGS station 

number

Date 

(month/

day/year)

Time QC sample type Pyrene Tetrachloro- ethene Tribromo- methane Tributyl phosphate Triclosan Triethyl citrate Triphenyl phosphate P34470 P34476 P34288 P62089 P62090 P62091 P62092

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <.5 <.5 <1.0 <.5 <.5

T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <.5 <.5 <1.0 <.5 <.5

O1 400920105051001 4/14/2005 1320 -- <.5 <.5 <.5 E.320 E.56 E.360 E.150

M6 400911105042500 4/14/2005 1350 -- <.5 <.5 <.5 E.082 E.10 E.079 E.041

T8 400928105003401 4/14/2005 1730 -- <.5 <.5 <.5 E.039 E.15 E.067 E.028

M4 400937105002901 4/14/2005 1810 -- <.5 <.5 <.5 E.056 E.12 E.069 E.029

M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <.5 <.5 <1.0 <.5 E.023

M8 400919105051501 3/29/2006 1045 -- <.5 <.5 <.5 <.5 <1.0 <.5 <.5

T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <.5 <.5 <1.0 <.5 <.5

O1 400920105051001 3/29/2006 1115 -- <.5 <.5 <.5 E.18 E.77 .67 E.19

M6 400911105042500 3/29/2006 1145 -- <.5 <.5 <.5 E.12 E.47 E.30 E.12

T8 400928105003401 3/29/2006 1740 -- <.5 <.5 <.5 E.073 E.19 E.13 E.047

M4 400937105002901 3/29/2006 1810 -- <.5 <.5 <.5 E.084 E.21 E.14 E.056

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

O1 400920105051001 4/14/2005 1321 replicate <.5 <.5 <.5 E.290 E.52 E.360 E.140

M4 400937105002901 4/14/2005 1812 spike .69 E.38 E.67 .88 E.86 .84 .83M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <.5 <.5 <1.0 <.5 E.021

M6 400911105042500 3/29/2006 1147 spike .71 E.17 E.65 1.34 1.31 1.26 .99

T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <.5 <.5 <1.0 <.5 <.5

Approach and Results 23
Table 4. Data from the analysis of wastewater compounds and associated field properties.—Continued

Units are micrograms per liter unless otherwise specified. USGS, U.S. Geological Survey; QC, quality control; --, not applicable or not analyzed; E, estimated; PXXXXX, USGS laboratory parameter code; <, less than]

Site number USGS station number Date (month/ day/year) Time QC sample type Tris(2-butoxyethyl) phosphate Tris(2-chloroethyl) phosphate Tris(dichloroisopropyl) phosphate Dichlorvos P62093 P62087 P62088 P38775

Environmental samples

M9 401011105084701 4/14/2005 0720 -- <0.5 <0.5 <0.5 --

M8 400919105051501 4/14/2005 1300 -- <.5 <.5 <.5 --T11 400918105051601 4/14/2005 1305 -- <.5 <.5 <.5 --O1 400920105051001 4/14/2005 1320 -- 4.5 E.290 E.460 --M6 400911105042500 4/14/2005 1350 -- .8 E.068 E.130 --T8 400928105003401 4/14/2005 1730 -- .84 E.110 E.075 --M4 400937105002901 4/14/2005 1810 -- .76 E.100 E.098 --M9 401011105084701 3/28/2006 1900 -- <.5 <.5 <.5 --M8 400919105051501 3/29/2006 1045 -- E.24 <.5 <.5 --T11 400918105051601 3/29/2006 1100 -- <.5 <.5 <.5 --O1 400920105051001 3/29/2006 1115 -- E9.37 E.28 E.35 --M6 400911105042500 3/29/2006 1145 -- E5.19 E.18 E.25 --T8 400928105003401 3/29/2006 1740 -- E4.45 E.16 E.21 --M4 400937105002901 3/29/2006 1810 -- E3.93 E.14 E.19 --

Quality-control samples

M8 400919105051501 4/14/2005 1230 blank <0.5 <0.5 <0.5 --O1 400920105051001 4/14/2005 1321 replicate 4.4 E.240 E.380 --M4 400937105002901 4/14/2005 1812 spike 1.6 .87 .91 E0.069

M9 401011105084701 3/28/2006 1901 replicate <.5 <.5 <.5 --

M6 400911105042500 3/29/2006 1147 spike E5.01 1.02 1.11 --T8 400928105003401 3/29/2006 1700 blank <.5 <.5 <.5 --

24  Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 5. Percent difference between environmental and replicate samples and percent recovery of spike concentrations of 

wastewater compounds.

U.S. Geological 

Survey parameter codeParameter name

Percent difference between 

environmental and replicate 

samples

Percent recovery of spike 

concentrations

2005 2006 2005 2006

34572 1,4-Dichlorobenzene 6 0 79 61

62054 1-Methylnaphthalene 0 0 91 88

62055 2,6-Dimethylnaphthalene 0 0 90 93

62056 2-Methylnaphthalene 0 0 88 86

62057 3-beta-Coprostanol 18 0 60 78

62058 3-Methyl-1H-indole 28 0 92 106

62059 3-tert-Butyl-4-hydroxyanisole 0 0 64 113

62060 4-Cumylphenol 0 0 89 133

62061 4-Octylphenol 0 0 86 94

62085 4-Nonylphenol 9 0 80 82

62062 4-tert-Octylphenol 0 0 101 117

62063 5-Methyl-1H-benzotriazole 7 0 63 95

62066 Anthraquinone 0 0 100 123

62064 Acetophenone 0 0 110 108

62065 Acetyl-hexamethyl-tetrahydro-naphthalene 11 0 92 108

34221 Anthracene 0 0 83 96

34248 Benzo[a]pyrene 0 0 68 60

62067 Benzophenone 20 0 98 122

62068 beta-Sitosterol 37 0 63 66

62086 beta-Stigmastanol 58 0 44 75

62069 Bisphenol A 26 16 101 106

04029 Bromacil 0 0 106 128

50305 Caffeine 16 0 90 106

62070 Camphor 8 0 95 100

82680 Carbaryl 0 0 125 105

62071 Carbazole 0 0 86 102

38933 Chlorpyrifos 0 0 94 113

62072 Cholesterol 23 0 56 74

62005 Cotinine 6 0 88 117

62082 N,N-diethyl-meta-toluamide (DEET) 0 0 88 125

39572 Diazinon 0 0 101 123

62083 Diethoxynonylphenol 13 0 172 206

61705 Diethoxyoctylphenol 10 0 100 159

62073 d-Limonene 0 0 49 29

61706 Monoethoxyoctylphenol 0 0 84 130

34377 Fluoranthene 0 0 86 91

62075 Hexahydrohexamethyl cyclopentabenzopyran 0 0 89 113

62076 Indole 13 0 84 92

Approach and Results 25
U.S. Geological 

Survey parameter codeParameter name

Percent difference between 

environmental and replicate 

samples

Percent recovery of spike 

concentrations

2005 2006 2005 2006

62077 Isoborneol 0 0 100 108

34409 Isophorone 0 0 103 114

62078 Isopropylbenzene 0 0 63 38

62079 Isoquinoline 0 0 99 115

62080 Menthol 0 0 98 112

50359 Metalaxyl 2 0 100 144

62081 Methyl salicylate 0 0 98 106

39415 Metolachlor 0 0 94 126

34443 Naphthalene 9 100 89 85

62084 p-Cresol 7 0 98 99

34462 Phenanthrene 0 0 90 92

34466 Phenol 5 30 40 100

04037 Prometon 0 0 101 126

34470 Pyrene 0 0 86 89

34476 Tetrachloroethylene 0 0 48 22

34288 Bromoform 0 0 84 82

62089 Tributyl phosphate 9 0 103 152

62090 Triclosan 7 0 93 105

62091 Triethyl citrate 0 0 96 120

62092 Triphenyl phosphate 7 6 100 109

62093 Tris(2-butoxyethyl) phosphate 2 0 105 -23

62087 Tris(2-chloroethyl) phosphate 17 0 96 105

62088 Tris(dichloroisopropyl) phosphate 17 0 102 108

Table 5. Percent difference between environmental and replicate samples and percent recovery of spike concentrations of 

wastewater compounds.—Continued

26 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Table 6. Data from the toxicity assays conducted on dialysates from the semipermeable membrane devices.

[USGS, U.S. Geological Survey; LR, laboratory replicate; --, not applicable; <, less than; %difference, percent difference between the environmental and replicate samples]

Site 

number

USGS station 

number

Type of 

quality-control 

sample

Toxicity, in picograms of toxic equivalents per milliliter

2005 sampling event 2006 sampling event

LR 1 LR 2 LR 3 LR 1 LR 2 LR 3

Environmental samples

M9 401011105084701 -- 132 145 <125 229 179 262

M8 400919105051501 -- 1,993 2,460 2,215 1,227 1,127 1,145

T11 400918105051601 -- 907 1,333 926 458 477 436

M6 400911105042500 -- 2,038 1,604 1,606 816 673 830

T8 400928105003401 -- 941 950 804 895 822 909

M4 400937105002901 -- 916 1,189 957 937 951 1,265

Quality-control samples

M6 400911105042500 Replicate 1,581 1,522 1,516 -- -- --

M6 400911105042500 %difference 29 5 6 -- -- --

M4 400937105002901 Replicate 1,230 1,720 1,481 -- -- --

M4 400937105002901 %difference 26 31 35 -- -- --

M9 401011105084701 Replicate -- -- -- 210 203 265

M9 401011105084701 %difference -- -- -- 9 12 1

T8 400928105003401 Replicate -- -- -- 795 747 810

T8 400928105003401 %difference -- -- -- 13 10 12

-- -- Dialysis blank <125 126 <125 <165 <165 <165

-- -- Trip blank <125 166 <125 <165 <165 <165

Approach and Results 27
References Cited

Baxter, G.T., and Stone, M.D., 1995, Fishes of Wyoming: 

Cheyenne, Wyo., Wyoming Game and Fish Department, 

290 p.

Becker, G.C., 1983, Fishes of Wisconsin: Madison, Wis., 

University of Wisconsin Press, 1,052 p.

Beckman, W.C., 1952, A guide to the fishes of Colorado: 

Boulder, Colo., University of Colorado Museum Leaflet 11, 

110 p.

Behnke, R.J., 1992, Native trout of Western North America: 

Bethesda, Md., American Fisheries Society, Monograph 6, 

275 p.

Bestgen, K.R., 1989, Distribution and notes on the biology 

of Phoxinus eos (Cyprinidae) in Colorado: Southwestern 

Naturalist, v. 34, p. 225–231.

Bestgen, K.R., Fausch, K.D., and Riley, S.C., 1991, Rediscovery of a relict southern-population of lake chub, Couesius 

plumbeus, in Colorado: Southwestern Naturalist, v. 36, 

p. 125–127.

Bestgen, K.R., Zelasko, K.A., and Compton, R.I., 2003, 

Environmental factors limiting suckermouth minnow 

Phenacobius mirabilis populations in Colorado: Fort 

Collins, Colorado State University, Larval Fish Laboratory 

Contribution 136, 83 p.

Cancalosi, J.J., 1981, Fishes of the Republican River basin in 

Colorado: Fort Collins, Colorado State University, Department of Zoology and Entomology, M.S. thesis, 87 p.

Cockerell, T.D.D., 1908, Fishes of the Rocky Mountain 

region: University of Colorado Studies, v. 5, p. 159–178.

Cross, F.B., and Collins, J.T., 1995, Fishes in Kansas (2d ed.): 

Lawrence, University of Kansas Museum of Natural History, Public Education Series No. 14, 315 p.

Dawley, R.M., Schultz, R.J., and Goddard, K.A., 1987, 

Clonal reproduction and polyploidy in unisexual hybrids of 

Phoxinus eos and Phoxinus neogaeus (Pisces: Cyprinidae): 

Copeia, v. 1987, p. 275–283.

Edmunds, G.F. and McCafferty, W.P., 1984, Ephemera 

compar—An obscure Colorado burrowing mayfly 

(Ephemeroptera: Ephemeridae): Entomological News, 

v. 95, p. 196–188.

Ellis, M.M., 1914, Fishes of Colorado: University of Colorado 

Studies, v. 11, p. 1–136.

Fausch, K.D., and Bestgen, K.R., 1996, Ecology of fishes 

indigenous to the Central and Southwestern Great Plains, in

Knopf, F.L., and Samson, F.B., eds., Ecology and conservation of Great Plains vertebrates: New York, Springer-Verlag, 

Inc., p. 131–166.

Goddard, K.A., Megwinoff, O., Wessner, L.L., Giaimo, F., 

1998, Confirmation of gynogenesis in Phoxinus eosneogaeus (Pisces: Cyprinidae): Journal of Heredity, v. 89, 

p. 151–157.

Hendricks, L.J., 1950, The fishes of Boulder County, Colorado: Boulder, University of Colorado, M.S. thesis, 55 p.

Herrmann, S.J., Ruiter, D.E., and Unzicker, J.D., 1986, Distribution and records of Colorado Trichoptera: Southwestern 

Naturalist, v. 31, p. 421– 457.

Huckins, J.N., Tubergen, M.W., and Manuweera, G.K., 1990, 

Semipermeable membrane devices containing model 

lipid—A new approach to monitoring the availability of 

lipophilic contaminants and estimating their bioconcentration potential: Chemosphere, v. 20, p. 533–552.

Hunter, Chris, 1997, Fishes of special concern, an update: 

Montana Outdoors, November/December, p. 26–27.

Jordon, D.S., 1891, Report of explorations in Colorado and 

Utah during the summer of 1889, with an account of the 

fishes found in each of the river basins examined: U.S. Fish 

Commission Bulletin, v. 9, p. 1– 40.

Juday, C., 1904, Fishes of Boulder County: University of 

Colorado Studies, v. 2, p. 113–114.

Juday, C., 1905, A list of fishes collected in Boulder County, 

Colorado, with a description of a new species of Leucisus: 

United States Bureau Fisheries Bulletin, v. 24, p. 225–227.

Kilpatrick, F.A., 1970, Dosage requirements for slug injections 

of Rhodamine BA and WT dyes: U.S. Geological Survey 

Professional Paper 700-B, p. 250–253.

Kolpin, D.W., Furlong, E.T., Meyer, M.T., Thurman, E.M., 

Zaugg, S.D., Barber, L.B., and Buxton, H.T., 2002, Pharmaceuticals, hormones, and other organic wastewater contaminants in United States streams, 1999-2000—A national 

reconnaissance: Environmental Science and Technology, 

v. 36, no. 6, p. 1,202–1,211.

Kondratieff, B.C., and Baumann, R.W., 2002, A review of the 

stoneflies of Colorado with description of a new species of 

Capnia (Plecoptera: Capniidae): Transactions of the American Entomological Society, v. 128, p. 385–401.

Li, H.W., 1968, Fishes of the South Platte River Basin: Fort 

Collins, Colorado State University, M.S. thesis, 67 p.

28  Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Litke, D.W., and Kimbrough, R.A., 1998, Water-quality 

assessment of the South Platte River Basin, Colorado, 

Nebraska, and Wyoming—Environmental setting and water 

quality of fixed sites, 1993–1995: U.S. Geological Survey 

Water-Resources Investigations Report 97–4220, 61 p.

Lynch, J.D., 1988, Habitat utilization by an introduced fish, 

Gambusia affinis, in Nebraska (Actinopterygii: Poecilidae): 

Transactions of the Nebraska Academy of Science, v. 16, 

p. 63– 67.

Markus, H.C., 1934, Life history of the blackhead minnow 

(Pimephales promelas): Copeia, v. 3, p. 116–122.

McCafferty, W.P., 2001, Status of some historically unfamiliar 

American mayflies (Ephemeroptera): Pan-Pacific Entomologist, v. 77, p. 210–218.

McCafferty, W.P., Durfee, R.S., and Kondratieff, B.C., 1993, 

Colorado mayflies (Ephemeroptera)—An annotated inventory: Southwestern Naturalist, v. 38, p. 252–274.

McMurry, L.M., Oethinger, M., and Levy, S.B., 1998, Overexpression of marA, soxS, or acrAB produces resistance to 

triclosan in laboratory and clinical strains of Escherichia 

coli: FEMS Microbiology Letters, v. 166, no. 2, p. 305–309.

Meffe, G.K., 1985, Predation and species replacement in 

American southwestern fishes, a case study: Southwestern 

Naturalist, v. 116, p. 1–11.

Missouri Natural Heritage Program (MNHP), 2006, Missouri 

species and communities of conservation concern checklist: 

Jefferson City, Missouri Department of Conservation, 58 p.

Moore, G.A., 1944, Notes on the early life history of Notropis 

girardi: Copeia, v. 4, p. 209–214.

Murk, A.J., Legler, J., Penison, M.S., Giesy, J.P., Vande 

Guchte, C., and Brouwer, A., 1996, Chemical activated 

luciferase gene expression (calux)—A novel in vitro bioassay for AH receptor active compounds in sediment and 

pore water: Fundamental and Applied Toxicology, v. 33, 

p. 149–160.

Needham, J.G., and Claassen P.W., 1925, A monograph of the 

Plecoptera or stoneflies of America north of Mexico: Entomological Society of North America, Thomas Say Foundation, v. 2, 397 p.

Nesler, T.P., Van Buren, Randy, Stafford, J.A., and Jones, 

Mark, 1997, Inventory and status of South Platte River 

native fishes in Colorado: Colorado Division of Wildlife, 

Final Report, 111 p.

Patton, T.M., 1997, Distribution and status of fishes in the 

Missouri River drainage in Wyoming—Implications for 

selecting conservation areas: Laramie, University of Wyoming, Ph.D. dissertation, 173 p.

Pflieger, W.L., 1997, The Fishes of Missouri: Jefferson City, 

Missouri Department of Conservation, 372 p.

Platania, S.P., Cummings, T.R., and Kehmeier, K.J., 1986, 

First verified record of the stonecat (Noturus flavus (Ictularidae) in the South Platte River system, Colorado, with 

special notes on an albinistic specimen: The Southwestern 

Naturalist, v. 31, p. 553–555.

Propst, D.L., 1982, Warmwater fishes of the Platte River 

Basin, Colorado; distribution, ecology, and community 

dynamics: Fort Collins, Colorado State University, Ph.D. 

dissertation, 283 p.

Propst, D.L., and Carlson, C.A., 1986, The distribution and 

status of warmwater fishes in the Platte River drainage, 

Colorado: The Southwest Naturalist, v. 31, p. 149–167.

Propst, D.L., and Carlson, C.A., 1989, Life history notes 

and distribution of the Johnny darter, Etheostoma nigrum

(Percidae) in Colorado: The Southwest Naturalist, v. 34, 

p. 250–259.

Repsys, A.J., Applegate, R.L., Hales, D.C., 1976, Food and 

food selectivity of the black bullhead, Ictalurus melas, 

in Lake Poinsett, South Dakota: Journal of the Fisheries 

Research Board of Canada, v. 33, p. 768–775.

Ruddy, B.C., and Britton, L.J., 1989, Traveltime and reaeration of selected streams in the North Platte and Yampa River 

Basins, Colorado: U.S. Geological Survey Water-Resources 

Investigations Report 88–4205, 56 p.

Scheurer, J.A., and Fausch, K.D., 2003, Multiscale processes 

regulate brassy minnow persistence in a Great Plains river: 

Transactions of the American Fisheries Society, v. 132, 

p. 840–855.

Schlosser, I.J., Doeringsfield, M.R., Elder, J.F., and Arqayus, 

L.F., 1998, Niche relationships of clonal and sexual fish in a 

heterogeneous landscape: Ecology, v. 79, p. 953–968.

Schmidt, K., 2006, Endangered, threatened, and special status 

fishes of North America: St. Paul, Minn., North American 

Native Fishes Association, version July 31, 2006, accessed 

August 15, 2006, at http://www.nanfa.org/bccconservation.

shtml.

Schrader, L.H., 1989, Use of the Index of Biotic Integrity to 

evaluate fish communities in western Great Plains streams: 

Fort Collins, Colorado State University, M.S. thesis, 120 p.

Schreurs, R.M., Legler, J., Artola-Garicano, E., Sinnige, T.L., 

Lanser, P.H., Seinen, W., and Van Der Burg, B., 2004, In 

vitro and in vivo antiestrogenic effects of polycyclic musks 

in zebrafish: Environmental Science and Technology, v. 38, 

no. 4, p. 997–1,002.

References Cited 29
Thorpe, K.L., Hutchinson, T.H., Hetheridge, M.J., Scholze, 

M., Sumpter, J.P., and Tyler, C.R., 2001, Assessing the 

biological potency of binary mixtures of environmental 

estrogens using vitellogenin induction in juvenile rainbow 

trout (Oncorhynchus mykiss): Environmental Science and 

Technology, v. 35, no. 12, p. 2,476–2,481.

U.S. Geological Survey, variously dated, National Field Manual for the Collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, 

book 9, chaps. A1–A9, available online at http://pubs.water.

usgs.gov/twri9A.

Ward, J.V., 1986, Altitudinal zonation in a Rocky Mountain 

stream: Archiv fuer Hydrobiologie–Supplementband, v. 74, 

no. 2, p. 133–199.

Wilson, B.A., Smith, V.H., Denoyelles, F., Larive, C.K., 2003, 

Effects of three pharmaceutical and personal care products 

on natural freshwater algal assemblages: Environmental 

Science and Technology, v. 37, no. 9, p. 1,713–1,719.

Wilson, J.F., Jr., Cobb, E.D., and Kilpatrick, F.A., 1986, Fluorometric procedures for dye tracing: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 3, 

chap. A12, 34 p.

Wiltzius, W.J., 1981, Compendium of introduction date and 

state and federal annual stocking of various fishes in Colorado, 1972–1978: Unpublished report, Colorado Division of 

Wildlife, Fort Collins, Colorado.

Woodling, John, 1985, Colorado’s little fish, a guide to the 

minnows and other lesser known fishes in the State of Colorado: Denver, Colorado Division of Wildlife, 77 p.

Zaugg, S.D., Smith, S.G., Schroeder, M.P., Barber, L.B., and 

Burkhardt, M.R., 2002, Methods of analysis by the U.S. 

Geological Survey National Water-Quality Laboratory—

Determination of wastewater compounds by polystyrenedivinylbenzene solid-phase extraction and capillary-column 

gas chromatography/mass spectrometry: U.S. Geological 

Survey Water-Resources Investigations Report 01–4186, 

37 p.

Zuellig, R.E., Kondratieff, B.C., and Hood, R.W., 2006, 

Studies on stoneflies (Plecoptera) of Colorado with eastern 

faunal affinities, including a new state record of the midwestern salmonfly, Pteronarcys pictetii Hagen (Plecoptera: 

Pteronarcyidae): Proceedings of the Entomological Society 

of Washington, v. 108, p. 335–340.

30 Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006
Zuellig and others—Aquatic Communities and Selected Water Chemistry in St. Vrain Creek, near Longmont, Colorado, 2005 and 2006—Data Series 253

Printed on recycled paper