U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2013–1051

Water Temperature and Baseflow Discharge of Streams 

Throughout the Range of Rio Grande Cutthroat Trout in 

Colorado and New Mexico—2010 and 2011
 
Water Temperature and Baseflow 

Discharge of Streams Throughout the 

Range of Rio Grande Cutthroat Trout in 

Colorado and New Mexico—2010 and 2011

By Matthew P. Zeigler, Andrew S. Todd, and Colleen A. Caldwell

Open-File Report 2013–1051

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

To learn about the USGS and its information products visit http://www.usgs.gov/

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:

Zeigler, M.P., Todd, A.S., and Caldwell, C.A., 2013, Water temperature and baseflow discharge of streams throughout 

the range of Rio Grande cutthroat trout in Colorado and New Mexico—2010 and 2011: U.S. Geological Survey OpenFile Report 2013–1051, 18 p., http://pubs.usgs.gov/of/2013/1051/.
iii

Acknowledgments

Funding for this project was supported by the U.S. Geological Survey Science Support 

Partnership, the USGS Climate Change and Wildlife Science Center, and T&E, Inc. Additional 

support was provided by New Mexico State University, Agricultural Experiment Station, 

and the Department of Fish, Wildlife and Conservation Ecology. We would also like to thank 

R. Galindo and S. Hall for field assistance as well as K. Patten (New Mexico Department of

Game and Fish), J. Alves (Colorado Division of Wildlife), D. Storch (U.S. Forest Service),

C. Cook (U.S. Forest Service), and S. Oetker (U.S. Fish and Wildlife Service) for valuable

information of study streams and logistical support. 

v

Contents

Acknowledgments .......................................................................................................................................iii

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

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

Purpose and Scope ......................................................................................................................................2

Study Area ......................................................................................................................................................2

Data-Collection Methods .............................................................................................................................4

Site Selection ........................................................................................................................................4

Collection of Data .................................................................................................................................4

Quality Control .............................................................................................................................................10

Stream and Air Temperature Data ..................................................................................................10

Stream-Discharge Data ....................................................................................................................10

Results ..........................................................................................................................................................10

Water Temperature ...........................................................................................................................10

Air Temperature .................................................................................................................................13

Comparison with Colorado’s Water Temperature Criteria ..........................................................13

Discharge ............................................................................................................................................13

Summary .......................................................................................................................................................17

References ...................................................................................................................................................17

Appendix A: Monitoring Site Data for Rio Grande Cutthroat Trout Populations (two parts 

available online at http://pubs.usgs.gov/of/2013/1051/)

Figures

1. Map showing historical range of Rio Grande cutthroat trout and monitoring 

sites within selected fourth level (8-digit) hydrological units ..............................................3

2. Map showing location of monitoring sites and documented Rio Grande cutthroat 

trout (RGCT) populations within the historical range of the subspecies ............................5

3. Graphs showing weekly average temperature (WAT) within streams containing 

Rio Grande cutthroat trout (WAT is calculated as the 7-day running average of 

the daily average temperature for that day and the prior 6 days) .....................................11

4. Graphs showing daily maximum (DM) temperatures as measured in three regions 

within the distribution of Rio Grande cutthroat trout (DM is the maximum daily 

value of the running 2-hour average) .....................................................................................12

5. Graphs showing summary water temperature metrics calculated from water 

temperature datasets collected in 2010 and 2011 ................................................................14

6. Graphs showing flow hydrographs for U.S. Geological Survey or Colorado 

Division of Water Resources monitored gage stations (within or in close 

proximity to Rio Grande cutthroat trout streams) used for comparison of 

measured discharge values in this study ..............................................................................15

7. Graphs showing measured baseflow discharge at sites within occupied Rio 

Grande cutthroat trout streams: A, 2010 (n = 54) and B, 2011 (n = 90) ..............................16
vi

Table

1. Landscape, stream temperature, and summer baseflow metrics for study 

streams within the current distribution of Rio Grande cutthroat trout ...............................6

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

hectare (ha) 2.471 acre

square kilometer (km2) 247.1 acre

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s)

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/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 insert datum name (and abbreviation) here, 

for instance, “North American Vertical Datum of 1988 (NAVD 88)”

Horizontal coordinate information is referenced to the insert datum name (and abbreviation) 

here, for instance, “North American Datum of 1983 (NAD 83)”
Water Temperature and Baseflow Discharge of Streams 

Throughout the Range of Rio Grande Cutthroat Trout in 

Colorado and New Mexico—2010 and 2011

By Matthew P. Zeigler, Andrew S. Todd, and Colleen A. Caldwell

Abstract

This study characterized the thermal regime in a 

number of Colorado and New Mexico streams that contain 

populations of Rio Grande cutthroat trout and had no previous 

record of continual temperature records. When compared 

to Colorado’s water temperature criteria (Cold Tier 1), a

portion of these populations appeared to be at risk from 

elevated stream temperatures, as indicated by exceedance of 

both acute (17–22 percent) and chronic (2–9 percent) water

quality metrics. Summer water temperature profiles recorded 

at sites within current Rio Grande cutthroat trout habitat 

indicated that although the majority of currently occupied 

conservation streams have temperatures that fall well below 

these biologically based acute and chronic thermal thresholds, 

several sites may be at or approaching water temperatures 

considered stressful to cutthroat trout. Further, water 

temperatures should be considered in decisions regarding 

the current and future thermal suitability of potential Rio 

Grande cutthroat trout restoration sites. Additionally, baseflow 

discharge sampling indicated that a majority of the sampled 

stream segments containing Rio Grande cutthroat trout have 

flows less than 1.0 cubic feet per second (cfs) in both 2010

(74 percent) and 2011 (77 percent). The relative drought

sensitivity of these low baseflow streams containing Rio 

Grande cutthroat trout should be further evaluated to assess 

their probable sustainability under possible future drought 

conditions. 

Introduction

The Rio Grande cutthroat trout (Oncorhynchus clarkii 

virginalis) is the southernmost subspecies of cutthroat trout, 

endemic to the Rio Grande, Canadian, and Pecos River 

Basins of New Mexico and southern Colorado (Behnke,

2002). Currently, the Rio Grande cutthroat trout occupies 

approximately 12 percent of its historical distribution (Alves

and others, 2008), having lost historical habitat through 

introduction of nonnative salmonids and human-made habitat 

alterations (Pritchard and Cowley, 2006). This contraction of

available habitat has fragmented historically interconnected 

populations, isolating the majority of remaining populations 

to high elevation (above 2,500 meters [m]) headwater

streams (Alves and others, 2008). Many of these remaining

populations are at risk of extirpation because of one or more 

risks including low population densities, reduced lengths of 

occupied stream habitat, nonnative trout, or climate change 

(U.S. Federal Register, 2008). A recent status review found

that listing the subspecies under the Endangered Species 

Act of 1973 was warranted but precluded by higher priority 

actions.

An important, yet largely uncharacterized, threat to the 

subspecies is the potential effects of future climate change. 

Average global air temperature is projected to increase up to 

4 degrees Celsius (°C) (relative to 1980–1999 period) by the

end of the 21st century (Intergovernmental Panel on Climate

Change, 2007), a change which could have devastating effects 

on aquatic ecosystems through altered stream temperature and 

hydrological regimes (as in shifts in the timing and magnitude

of snowmelt), as well as contributing to an anticipated 

increase in the frequency and intensity of stochastic events 

such as wildfire, drought, and flooding. Recent investigation 

into climate change within the historical range of Rio Grande 

cutthroat trout has indicated that since 1963, significant 

increases in air temperature, shifts in the hydrological regime, 

and decreases in snowpack have already occurred across the 

range of the subspecies (Zeigler and others, 2012).

Temperature influences almost all life-cycle aspects of 

fish and ultimately defines the relative thermal suitability of 

a given habitat for a particular species (Magnuson and others,

1979). For example, temperatures above the optimal range 

of a subspecies can increase metabolic demand and cause 

decreases in growth if food intake does not compensate for 

the increase in metabolic demand (Jobling, 1997). Rio Grande

cutthroat trout are stenothermic ectotherms, requiring cold 

water habitats to survive. Water temperature can also influence 

interactions with other fish (De Staso and Rahel, 1994),

distribution (Dunham and others, 2003), reproductive success

(Winkle and others, 1997), and ultimately survival (Bear

and others, 2007). As such, warming stream temperatures 
2 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

can decrease habitat available for salmonids by increasing 

temperature above the suitable thermal range for the species. 

In extreme cases, warming stream temperatures can render 

particular stream reaches or even entire streams uninhabitable. 

Laboratory studies have indicated that Rio Grande cutthroat 

trout have a 30-day (d) ultimate upper incipient lethal

temperature (UUILT, temperature lethal to 50 percent of the

population) of 22.1 °C, similar to other subspecies of cutthroat

trout, but cooler than the upper thermal limits of nonnative 

salmonids that occur in the current range of the subspecies 

(Zeigler, 2012).

Stream discharge is also important in determining 

growth, survival, and distribution of salmonids, as many 

critical life history components (such as spawning) are linked

to specific flow regimes and time-dependent cues (Behnke,

2002). For example, decreased baseflows limited growth 

in some salmonids (Harvey and others, 2006), and fish

size has also been positively linked to the size of available 

pools (Harvey and Stewart, 1991). Low to no discharge can

affect flow-sensitive riffle habitat with a concurrent loss of 

hydrological connectivity (Lake, 2003). In the Southwest

United States, precipitation is expected to decrease in the 

future, thereby increasing drought severity and drought length 

(Hoerling and Eischied, 2007). We anticipate that alterations

to the hydrological cycle, caused by changes in precipitation, 

may reduce baseflow to the point of limiting occupiable 

habitat of Rio Grande cutthroat trout. 

As detailed above, the importance of temperature 

and flow regimes on the survival and success of salmonid 

populations is unequivocal. In addition to the effects on 

stream-dwelling fishes, reduced discharge can influence water 

temperatures as smaller water volumes are more easily heated 

by warm air temperatures and solar radiation (Webb and

others, 2008). Prior to this study little data on current thermal 

regimes and baseflow discharge had been systematically 

collected within the majority of streams currently occupied by 

Rio Grande cutthroat trout. Understanding existing thermal 

and baseflow conditions experienced by the subspecies in 

streams where populations occur is important in evaluating 

the vulnerability of the subspecies to climate-related changes 

as well as providing resource managers with information to 

assess the climate-related suitability of potential restoration 

streams. To facilitate key resource management decisions, 

a comprehensive monitoring network of a total of 69 sites 

located within currently occupied and potential Rio Grande 

cutthroat trout restoration streams was established in the 

spring of 2010. This network was expanded to 108 sites by the 

fall of 2011.

In 2007, Colorado revised its statewide water quality 

criteria for water temperature based on a rigorous review of 

the literature that addressed the thermal requirements of fish 

species residing in Colorado (Todd and others, 2008). The

purpose of the development of these criteria was to protect 

resident fish, including native species such as cutthroat 

trout, from acute and chronic thermal stress. Although 

these temperature criteria have yet to be implemented as 

site-specific standards within the Rio Grande watershed in 

Colorado and do not apply in New Mexico, they are used 

herein as a comparison point between existing thermal 

conditions documented within streams containing Rio Grande 

cutthroat trout and biologically based thermal thresholds. 

Purpose and Scope

In this report, we focus on water temperature and 

baseflow hydrology as “climate-sensitive” environmental 

variables within a network of 108 sites throughout the 

current geographic distribution of Rio Grande cutthroat trout. 

Reported data were collected between May 2010 and October

2011 (most recent analysis at the time of this report). Not all

sites have data for all years because of the gradual expansion 

of this network and the occasional loss of data loggers at 

individual sites. This report (1) summarizes all water and air

temperature data collected in watersheds within the current 

distribution of the Rio Grande cutthroat trout, (2) summarizes

site-specific water temperature metrics, (3) compares these

summary metrics to biologically based water temperature 

thermal criteria, and (4) lists all baseflow hydrology

measurements within the network. 

Study Area

The historical range of the Rio Grande cutthroat trout 

encompasses approximately 214,000 square kilometers (km2) 

in northern New Mexico and southern Colorado (fig. 1) and

includes the Rio Grande (8,689 kilometers (km)) and Pecos

(1,002 km) River Basins from their headwaters to the Texas

border and the majority of the Canadian River (1,026 km)

Basin in New Mexico. Historically, Rio Grande cutthroat trout 

are thought to have occupied approximately 10,700 km of 

streams within this large geographic area. Historical habitat 

was equally split between Colorado (48.5 percent) and New

Mexico (51.5 percent), although more geographical area

occurs in New Mexico (Alves and others, 2008).

At the time of this report, the subspecies occurs within 

approximately 12 percent (1,302 km) of its historical habitat

(Alves and others, 2008). The majority of this currently

occupied habitat occurs in northern New Mexico and southern 

Colorado within the high elevation (1,829 m to 3,810 m)

headwater streams of the Sangre de Cristo, Jemez, and 

San Juan Mountain Ranges. Although one small restored 

population of Rio Grande cutthroat trout occurs south 

of Albuquerque, N. Mex., the majority of historical and 

present habitat occurs in northern New Mexico and southern 

Colorado. Thus, the study has focused primarily within these 

areas. Land ownership across the current distribution of 

Rio Grande cutthroat trout consists primarily of U.S. Forest 

Service (54 percent), private land (41 percent), National Park

Service (2 percent), and U.S. Bureau of Land Management,

Tribal, and State-owned lands (about 1 percent each) (Alves

and others, 2008).
Study Area 3

Figure 1. Historical range of Rio Grande cutthroat trout and monitoring sites within selected fourth level (8-digit) hydrological units.

109°0'W 108°0'W 107°0'W 106°0'W 105°0'W 104°0'W 103°0'W

38°0'N

37°0'N

36°0'N

35°0'N

34°0'N

33°0'N

32°0'N

Rio Grande 

Headwaters, site 1 Saguache, 

sites 2 - 16

San Luis,

sites 17 - 20

Alamosa-Trinchera,

sites 21 - 42

Conejos,

Sites 43 - 49

Rio Chama,

sites 55 - 59

Upper Rio 

Grande,

sites 60 - 99

Pecos 

Headwaters,

sites 103 - 107

Canadian 

Headwaters,

sites 50 - 51

Cimarron,

sites 52 - 53

Mora,

site 54 Jemez,

sites 100 - 101

Rio Puerco,

sites 102

Arroyo Del Macho,

site 108

COLORADO

NEW MEXICO

NEW MEXICO

TEXAS

EXPLANATION

Historical range of Rio Grande cutthroat trout

Study area

National Hydrology Dataset,1:100,000

NAD 1983 UTM Zone 13N

0 20 40 80 KILOMETERS

0 20 40 80 MILES
4 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

Data-Collection Methods

Site Selection

Selection of study streams was informed by collaborative 

input provided by parties signatory to the Rio Grande 

Cutthroat Trout Conservation Agreement (hereafter referred

to as “Agreement”), including the New Mexico Department 

of Game and Fish (NMDGF), Colorado Parks and Wildlife

(CPW), the U.S. Forest Service (Santa Fe, Carson, and Rio

Grande National Forests), the National Park Service (Great

Sand Dunes National Park), local tribes (the Mescalero

Apache Nation), and the U.S. Fish and Wildlife Service 

(USFWS) (RGCT Conservation Team, 2009). Initial selection

of study streams was based on current Rio Grande cutthroat 

trout populations characterized by the signatories as “high 

quality” based on genetic purity, lack of nonnative salmonids, 

and population size. Importantly, these streams were selected 

from a database of streams previously identified as containing 

Rio Grande cutthroat trout by signatories to the agreement, 

and independent validation of the presence of the fish was 

not conducted as part of this study. After initial site selection, 

several additional streams were added on the basis of requests 

from these State, Federal, and Tribal managers, including 

potential restoration sites, current restoration sites, or 

populations thought to be at risk because of a variety of threats 

related to future climate change. 

In total, 108 sites were selected for study of which 

97 sites fall within currently identified conservation 

populations which defines the continuous extent of a 

population of Rio Grande cutthroat trout unhindered by 

complete barriers (Alves and others, 2008) (fig. 2; table 1).

The remaining 11 stream sites were selected because they 

have been considered as potential restoration sites for Rio 

Grande cutthroat trout. Within each stream, at least one paired 

stream/air site was selected at or near the downstream extent

of a given conservation population. In general, monitoring 

sites located at the lowest extent of Rio Grande cutthroat trout 

populations were within occupied habitat unless otherwise 

prevented (appendix A). Additional sites within a unique

stream were selected on the basis of stream length and number 

of tributaries. For example, streams with occupied habitat 

of 8 km or greater, or those with unmonitored tributaries, 

warranted addition of sites to capture temperature variation 

because of the large spatial area. Within potential restoration 

streams, stream/air data loggers were deployed to correspond

to elevations of data loggers within sites of nearby streams 

occupied by the subspecies. 

Collection of Data

Certain stream conditions are known to cause 

thermal heterogeneity within a stream channel (such as

tributaries, beaver ponds, groundwater seepages). To 

prevent deployment of data loggers into sites that would 

not accurately represent the thermal regime of the stream, 

data loggers were moved upstream or downstream to 

ensure thermal homogeneity. Study sites at population 

termini, however, were only moved upstream to ensure data 

loggers remained within occupied habitat. Temperature data 

loggers were deployed within the thalweg of deep wellmixed habitats (as in runs), usually within areas covered by

riparian vegetation. 

Data loggers were calibrated (see “Quality Control”

section) then deployed between May 2010 and October

2011. Both air and stream temperature data loggers were 

programmed to record temperatures at 1-h intervals, an 

interval which has been demonstrated to have a small 

probability of missing true daily maximum temperatures, 

even within streams exhibiting high daily variation in water 

temperature (Dunham and others, 2005). Air and water

data loggers were housed in 3.81 millimeter (mm) white

polyvinyl chloride (PVC) pipe to prevent physical damage

and protect the data logger from direct exposure to solar 

radiation, which can bias temperature readings (Dunham

and others, 2005). Holes were drilled along the PVC

housings to ensure adequate flow-through of air and water. 

Stream housings were attached to predrilled metal stakes with 

coated copper wire and anchored within the stream thalweg 

with a sledgehammer. Air temperature data loggers were 

placed in housings within 50 m of the stream temperature 

logger and were suspended approximately 1.5 m above the 

ground on the north-facing side of a vegetative structure. 

Global Positioning System elevation and digital photographs 

were recorded for each stream/air temperature study site (see

appendix A).

Sites were revisited in the falls of 2010 and 2011, 

and both stream and air temperature data loggers were 

downloaded. At the time of site revisits, stream-discharge 

rates were measured at each thermograph site to evaluate 

and compare baseflow rates between streams. Measurements 

of discharge were conducted by using the midsection 

method, where velocity measurements are taken at the linear 

midsection of predefined intervals within the stream channel. 

Where feasible, 15–20 intervals were established within a

straight U-shaped channel section (Harrelson and others,

1994). If stream widths were too narrow to allow crosssection intervals of greater than 10 centimeters (cm), fewer

intervals were used (U.S. Environmental Protection Agency,

2004). Velocity measurements were taken at appropriate

depths following the methods of Rantz and others, 1982. 

Discharge was measured by using either a Marsh-McBirney 

Flo-Mate (Model 2000) or a U.S. Geological Survey (USGS)

Pygmy-MH Meter (Model 6225).
Data-Collection Methods 5

Figure 2. Location of monitoring sites and documented Rio Grande cutthroat trout (RGCT) populations within the historical range of the 

subspecies.

109°0'W 108°0'W 107°0'W 106°0'W 105°0'W 104°0'W 103°0'W

38°0'N

37°0'N

36°0'N

35°0'N

34°0'N

33°0'N

32°0'N

31°0'N

COLORADO

NEW MEXICO

NEW MEXICO

TEXAS

EXPLANATION

Monitoring Site

RGCT conservation population

RGCT current distribution

0 20 40 80 MILES

0 20 40 80 KILOMETERS
Table 1. Landscape, stream temperature, and summer baseflow metrics for study streams within the current distribution of Rio Grande cutthroat trored indicate water temperature values that exceed Colorado’s Cold Water Tier 1 water temperature criteria (Todd and others, 2008). Values highlighted measurements determined “precipitation affected,” as defined by the accumulation of more than 1.3 cm of precipitation measured at the nearest SNOday of the discharge measurement combined with the 2 days prior. —Continued [RGCT, Rio Grande cutthroat trout present (Y) or not present but considered potential restoration streams (N); Elevation (m), Drainage area (ha), 2-hr Max = yearly maximum 2maximum weekly average temperature; Q = summer baseflow discharge (cubic feet per second); “---“ refers to data not collected; “Exposed” refers to a data logger that was exppoint during the year and data is not reported; “Lost” refers to data loggers removed by vandalism or storm event] Site Stream name, state RGCT Elevation (m) Drainage area (ha) 2-hr max (°C) 2010 2-hr max (°C) 2011 MWAT (°C) 2010 MWAT (°C) 2011 

1 West Alder Creek, CO Y 2,654 5,018 --- 19.46 --- 14.40 2 East Middle Creek, CO Y 3,002 1,420 16.01 15.65 11.85 11.72 3 Jack's Creek, CO Y 2,518 7,720 22.07 20.57 16.15 14.81 4 Jack's Creek, CO Y 2,655 3,101 16.38 16.44 14.02 13.52 5 Cross Creek, CO Y 2,638 2,041 17.66 Lost 15.29 Lost 6 Big Spring Creek, CO Y 2,569 772 --- 20.57 --- 15.35 7 East Pass Creek, CO Y 2,789 1,302 --- 12.92 --- 11.52 8 Whale Creek, CO Y 3,144 1,279 --- --- --- --- 9 Carnero Creek, CO N 2,485 27,442 25.93 27.15 20.12 19.17 

10 North Fork Carnero Creek, CO Y 2,703 6,131 20.33 14.92 14.57 12.44 

11 South Carnero Creek, CO Y 2,681 10,984 22.29 21.12 17.18 16.72 

12 Middle Fork Carnero Creek, CO Y 2,756 4,298 17.90 19.59 14.09 13.84 13 Cave Creek, CO Y 2,767 2,324 16.87 17.06 14.45 13.59 14 Prong Creek, CO Y 3,011 1,684 18.37 18.06 13.81 13.04 15 La Garita Creek, CO N 2,553 14,729 25.55 25.87 18.36 18.33 16 La Garita Creek, CO N 2,690 10,647 22.12 22.13 15.99 15.91 17 Sand Creek, CO N 2,516 6,063 --- Lost --- Lost 18 Medano Creek, Y 2,583 4,167 Lost Lost Lost Lost 19 Medano Creek, CO Y 2,963 1,444 --- 15.08 --- 11.00 20 Little Medano Creek, CO Y 2,621 1,162 --- 10.31 --- 8.71 21 Jim Creek, CO Y 2,964 2,596 --- --- --- --- 22 Torsido Creek, CO Y 2,961 2,193 --- --- --- --- 23 Rhodes Gulch, Co Y 2,960 713 13.62 15.44 9.90 11.02 24 Cat Creek, CO Y 2,683 2,080 18.20 Exposed 15.57 Exposed 25 San Francisco Creek, CO Y 2,533 3,636 16.51 15.86 14.10 14.23 26 San Francisco Creek, CO Y 2,920 1,281 13.33 14.76 9.17 9.87 27 Ute Creek, CO N 2,463 10,375 23.26 Lost 16.75 Lost 

Table 1. Landscape, stream temperature, and summer baseflow metrics for study streams within the current distribution of Rio Grande cutthroat trored indicate water temperature values that exceed Colorado’s Cold Water Tier 1 water temperature criteria (Todd and others, 2008). Values highlighted measurements determined “precipitation affected,” as defined by the accumulation of more than 1.3 cm of precipitation measured at the nearest SNOday of the discharge measurement combined with the 2 days prior. [RGCT, Rio Grande cutthroat trout present (Y) or not present but considered potential restoration streams (N); Elevation (m), Drainage area (ha), 2-hr Max = yearly maximum 2maximum weekly average temperature; Q = summer baseflow discharge (cubic feet per second); “---“ refers to data not collected; “Exposed” refers to a data logger that was exppoint during the year and data is not reported; “Lost” refers to data loggers removed by vandalism or storm event]
Table 1. Landscape, stream temperature, and summer baseflow metrics for study streams within the current distribution of Rio Grande cutthroat trored indicate water temperature values that exceed Colorado’s Cold Water Tier 1 water temperature criteria (Todd and others, 2008). Values highlighted measurements determined “precipitation affected,” as defined by the accumulation of more than 1.3 cm of precipitation measured at the nearest SNOday of the discharge measurement combined with the 2 days prior. —Continued[RGCT, Rio Grande cutthroat trout present (Y) or not present but considered potential restoration streams (N); Elevation (m), Drainage area (ha), 2-hr Max = yearly maximum 2maximum weekly average temperature; Q = summer baseflow discharge (cubic feet per second); “---“ refers to data not collected; “Exposed” refers to a data logger that was exppoint during the year and data is not reported; “Lost” refers to data loggers removed by vandalism or storm event]

Site Stream name, state RGCT Elevation (m) Drainage area (ha) 2-hr max (°C) 2010 2-hr max (°C) 2011 MWAT (°C) 2010 MWAT (°C) 2011 

28 Little Ute Creek, CO Y 2,792 1,391 --- --- --- --- 29 Sangre de Cristo Creek, CO Y 2,473 28,392 24.32 Exposed 18.49 Exposed 30 West Indian Creek, CO Y 2,606 6,797 18.35 20.08 13.90 14.72 31 Wagon Creek, CO Y 2,641 3,902 18.65 19.31 14.98 14.82 32 Sangre de Cristo Creek, CO Y 2,568 10,894 --- --- --- --- 33 Placer Creek, CO Y 2,608 5,744 20.88 19.14 14.89 15.07 34 Trinchera Creek,CO Y 2,641 7,762 15.46 17.23 11.11 11.94 35 North Fork Trinchera Creek, CO Y 2,673 4,094 16.71 17.56 12.60 12.75 36 Deep Canyon Creek, CO Y 3,125 399 13.04 Lost 7.44 Lost 37 North Fork Vallegos Creek, CO Y 2,725 2,971 --- --- --- --- 38 South Fork Vallegos Creek, CO Y 2,668 2,200 --- --- --- --- 39 Alamosito Creek, CO Y 2,796 1,294 15.09 15.34 11.77 11.65 40 Torcido Creek, CO Y 2,961 1,208 16.49 16.43 13.78 13.32 41 Jaroso Creek, CO Y 2,932 1,203 15.65 16.20 12.61 12.59 42 Cuates Creek, CO Y 2,691 1,282 14.07 14.65 12.04 12.38 43 Tio Grande, NM Y 2,749 2,589 --- 24.52 --- 17.64 44 Rio Nutrias, NM Y 2,804 441 --- --- --- --- 45 Tanques Creek, NM Y 2,813 608 --- --- --- --- 46 Oiser Creek, CO Y 2,931 1,066 19.69 18.32 14.20 13.37 47 Cascade Creek, CO Y 2,970 654 18.76 Lost 14.37 Lost 48 Rio de los Pinos, CO Y 3,436 216 --- --- --- --- 49 Lake Fork Conejos Creek, CO Y 2,945 1,976 --- 20.77 --- 14.82 50 Richardo Creek, NM Y 2,554 4,748 18.06 19.65 13.46 14.48 51 Little Vermejo Creek, NM Y 2,559 2,972 22.82 24.94 15.77 16.51 52 McCrystal Creek, NM Y 2,440 2,726 25.07 Exposed 19.01 Exposed 53 Middle Ponil Creek, NM Y 2,915 1,276 --- Lost --- Lost 54 East Fork Luna Creek, NM Y 2,713 1,279 --- --- --- --- 55 Canones Creek, NM Y 2,473 4,325 19.75 19.56 15.82 15.46 
Table 1. Landscape, stream temperature, and summer baseflow metrics for study streams within the current distribution of Rio Grande cutthroat trored indicate water temperature values that exceed Colorado’s Cold Water Tier 1 water temperature criteria (Todd and others, 2008). Values highlighted measurements determined “precipitation affected,” as defined by the accumulation of more than 1.3 cm of precipitation measured at the nearest SNOday of the discharge measurement combined with the 2 days prior. —Continued [RGCT, Rio Grande cutthroat trout present (Y) or not present but considered potential restoration streams (N); Elevation (m), Drainage area (ha), 2-hr Max = yearly maximum 2maximum weekly average temperature; Q = summer baseflow discharge (cubic feet per second); “---“ refers to data not collected; “Exposed” refers to a data logger that was exppoint during the year and data is not reported; “Lost” refers to data loggers removed by vandalism or storm event] Site Stream name, state RGCT Elevation (m) Drainage area (ha) 2-hr max (°C) 2010 2-hr max (°C) 2011 MWAT (°C) 2010 MWAT (°C) 2011 

56 Canones Creek, NM Y 2,555 3,338 --- 23.53 --- 15.89 57 El Rito Creek, NM Y 2,576 6,477 26.33 --- 18.74 --- 58 Canjlion Creek, NM Y 2,831 1,247 Lost Lost Lost Lost 59 Wolf Creek, NM Y 2,940 1,071 --- --- --- --- 60 Rio de Truchas, NM Y 2,610 1,198 --- --- --- --- 61 Rio San Leonardo, NM Y 2,727 730 --- --- --- --- 62 Rio de las Trampas, NM Y 2,734 1,489 --- --- --- --- 63 Indian Creek, NM Y 2,774 551 --- --- --- --- 64 Jicarita Creek, NM Y 2,735 784 --- 14.76 --- 11.48 65 Middle Fork Rio Santa Barbara, NM Y 2,853 4,138 Lost Lost Lost Lost 66 West Fork Rio Santa Barbara, NM Y 2,842 2,498 --- 15.77 --- 10.17 67 East Fork Rio Santa Barbara, NM Y 3,148 1,479 14.31 --- 10.50 --- 68 Osha Canyon, NM Y 2,419 1,631 --- --- --- --- 69 Rito Angostura, NM Y 2,935 1,392 Lost --- Lost --- 70 Alamitos Creek, NM Y 2,951 1,788 --- 18.56 --- 12.40 71 Policarpio Creek, NM Y 2,772 779 15.93 16.53 11.23 11.19 72 Rio Grande del Rancho, NM Y 2,928 1,068 --- --- --- --- 73 Frijoles Creek, NM Y 2,923 804 --- --- --- --- 74 Yerba Creek, NM Y 2,516 619 --- --- --- --- 75 Manzanita Creek, NM Y 2,501 588 --- 7.36 --- 6.21 76 Italianos Creek, NM Y 2,677 581 15.57 15.78 11.87 11.92 77 Gavilan Creek, NM Y 2,775 764 --- --- --- --- 78 San Cristobal Creek, NM Y 2,497 1,200 12.74 14.24 10.78 11.44 79 Columbine Creek, NM Y 2,435 4,164 12.55 13.16 9.52 10.12 80 Columbine Creek, NM Y 2,583 1,451 --- 13.40 --- 10.37 81 Placer Fork, NM Y 2,581 1,324 --- 11.42 --- 9.43 82 Cabresto Creek, NM Y 2,852 2,415 16.23 17.40 11.66 11.81 
Table 1. Landscape, stream temperature, and summer baseflow metrics for study streams within the current distribution of Rio Grande cutthroat trored indicate water temperature values that exceed Colorado’s Cold Water Tier 1 water temperature criteria (Todd and others, 2008). Values highlighted measurements determined “precipitation affected,” as defined by the accumulation of more than 1.3 cm of precipitation measured at the nearest SNOday of the discharge measurement combined with the 2 days prior. —Continued[RGCT, Rio Grande cutthroat trout present (Y) or not present but considered potential restoration streams (N); Elevation (m), Drainage area (ha), 2-hr Max = yearly maximum 2maximum weekly average temperature; Q = summer baseflow discharge (cubic feet per second); “---“ refers to data not collected; “Exposed” refers to a data logger that was exppoint during the year and data is not reported; “Lost” refers to data loggers removed by vandalism or storm event]

Site Stream name, state RGCT Elevation (m) Drainage area (ha) 2-hr max (°C) 2010 2-hr max (°C) 2011 MWAT (°C) 2010 MWAT (°C) 2011 

83 Cabresto Creek, NM Y 3,088 906 --- 19.20 --- 12.65 84 Comanche Creek, NM Y 2,728 10,941 23.83 25.13 16.77 16.7 85 Comanche Creek, NM Y 2,780 7,440 --- 24.12 --- 15.95 86 Little Costilla Creek, NM Y 2,785 1,398 17.76 19.65 12.98 13.03 87 Comanche Creek, NM Y 2,816 5,078 Exposed Exposed Exposed Exposed 88 Grassy Creek, NM Y 2,825 474 Lost Lost Lost Lost 89 Comanche Creek, NM Y 2,852 1,352 24.51 26.24 16.78 16.25 90 Vidal Creek, NM Y 2,854 2,477 22.90 22.99 16.30 15.01 91 Costilla Creek, NM N 2,729 17,526 --- 22.51 --- 16.41 92 La Queva Creek, NM Y 2,745 852 --- --- --- --- 93 Powderhouse Creek, NM Y 2,948 903 18.19 17.89 12.50 12.84 94 Santistevan Creek, NM N 2,885 592 --- 16.12 --- 11.75 95 Casias Creek, NM N 2,885 4,157 17.62 20.48 12.05 13.38 96 Casias Creek, NM N 2,988 1,883 --- 17.55 --- 11.47 97 Costilla Creek, NM Y 3,097 1,678 22.39 23.22 13.24 13.38 98 West Fork Costilla Creek, NM Y 3,149 481 19.21 19.22 11.40 11.04 99 East Fork Costilla Creek, NM Y 3,149 550 20.25 22.51 11.66 12.17 

100 Rio de las Vacas, NM Y 2,754 3,487 --- --- --- --- 101 Rio de las Palomas, NM Y 2,571 1,120 --- --- --- --- 102 La Jara Creek, NM Y 2,451 1,394 --- --- --- --- 103 Dalton Creek, NM Y 2,307 2,867 --- --- --- --- 104 Panchuela Creek, NM N 2,567 5,630 15.65 16.26 12.01 12.35 105 Cave Creek, NM N 2,642 1,820 --- 14.33 --- 11.92 106 Jack's Creek, NM Y 2,534 1,851 16.37 17.03 12.70 13.57 107 Jack's Creek, NM Y 3,147 654 Exposed Exposed Exposed Exposed 108 Pine Lodge Creek, NM Y 1,923 656 --- --- --- --- 
10 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

Quality Control

Stream and Air Temperature Data

Water temperature data loggers (Onset Computer

Corporation HOBO U22 Pro v2) were selected for

measurement of both stream and air temperature. The Pro v2 

has an operating range from -40 to 70 °C with an accuracy

of 0.2 over a 0–50 °C range and a resolution of 0.02 at 25 °C

(Onset Computer Corporation, 2009). Before deployment,

data loggers were calibrated by immersing each data logger 

into 0 and 25 °C water baths for 1 h (Schuett-Hames and

others, 1999; Dunham and others, 2005). During immersion,

the data loggers recorded temperatures at 2-minute intervals, 

and these data were subsequently compared to data obtained 

with a calibrated digital thermometer (Traceable Waterproof

Thermometer -50–300 °C). No data loggers showed any

significant deviation from temperatures recorded by the 

thermometer at either 0 or 25 °C.

Once downloaded from the field, each stream record

was quality-checked by examining periods of time when 

temperature increases were greater than 3 °C per hour,

single temperature readings exceeded 29 °C, and (or) daily

temperature ranges were in excess of 15 °C. When data from

a stream record exhibited these aforementioned responses, 

the data were reexamined and subsequently removed from 

further analysis if the data could not be adequately explained. 

For each stream record, hourly data were used to calculate 

individual daily (24-h) average temperatures. In addition, 2-h

rolling averages were used to identify annual temperature 

daily minimums and maximums (2-hr min and max; daily

maximum (DM)) and annual maximum weekly average

temperatures (maximum annual value of the rolling average of

mean daily water temperatures, MWAT, over a 7-day period) 

were calculated. When a stream record contained inadequate 

data to calculate representative summary metrics, the record 

was not included. For example, in streams that did not log 

summer water temperatures (for example, West Alder Creek

in 2010 [Site 1]), annual temperature maxima and MWAT

statistics were not calculated. Similarly, where only summer 

data were recorded, annual temperature minima and minimum 

weekly average temperature statistics were not calculated. 

Air temperature data were assessed for accuracy through 

graphical analysis. Very few records revealed temperatures

recorded out of seasonal context or malfunctioning data 

loggers, but any errors were removed, and the remaining data 

were used for further analysis. The same summary metrics for 

stream records (and exceptions) were then calculated for all air

temperature datasets (appendix A).

Stream-Discharge Data

The logistics of monitoring stream discharge across all 

sites within a large geographical area precluded the use of 

one type of flow meter. Although Marsh-McBirney Flo-Mate 

and the Pygmy-MH meter differ in methodology, both are 

used for the measurement of flow in small, wadeable streams. 

The Marsh-McBirney meter uses an electromagnetic method 

to measure velocity within a range from -0.15 meter per 

second (m/sec) to 6.10 m/sec. The Pygmy-MH meter uses a

vertical axis rotor to measure velocity and is recommended 

for shallow streams (Rantz and others, 1982) with a velocity

range from 0.03 m/sec to 1.50 m/sec. Soupir and others (2009)

demonstrated that the Marsh-McBirney meter performed the 

best over a wider range of flows, whereas the Pygmy-MH 

meter exhibited decreased accuracy under lower velocities. To 

reduce variability caused by low velocities that could affect 

the accuracy of the Pygmy-MH meter, this meter was used in 

streams above the recommended range of discharge.

Water velocity was obtained as described above, and the 

total discharge at each site was calculated as follows:

Q n n = ∑a V

where 

an is the area of subsection n calculated as the 

depth x width, 

Vn is the velocity of subsection n (Harrelson and

others, 1994). 

The effect of precipitation on discharge was determined 

by examining precipitation records from nearby Natural 

Resources Conservation Service SNOw TELemetry

(SNOTEL) stations. Sites that indicated cumulative

precipitation within three days of the discharge measurement 

were marked as “precipitation affected” (more than 1.3 cm

of precipitation measured at the nearest SNOTEL station on

the day of the discharge measurement combined with 2 days 

prior). Additionally, six study sites were within proximity of 

streamgages operated by USGS or Colorado Division of Water 

Resources (CDWR) which take discharge measurements at

regular intervals. At these locations, discharge was measured 

by using flow meters, and these values were compared to the 

corresponding measurement of USGS or CDWR streamgages 

at the time. 

Results

Water Temperature 

Several stream temperature data loggers were lost 

because of theft or high flows or were found to have been 

exposed to air (table 1). The remaining data loggers showed

no instance of errors, resulting in an accumulation of more 

than 30,000 days of thermal data. Temperature profiles 

from populations of Rio Grande cutthroat trout (except

for Manzanita Creek) are shown in figures 3 and 4. The 

seasonality of water temperatures in Rio Grande cutthroat 
Results 11

Figure 3. Weekly average temperature (WAT) within streams containing Rio Grande cutthroat trout (WAT is calculated as the 7-day 

running average of the daily average temperature for that day and the prior 6 days).
12 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

Figure 4. Daily maximum (DM) temperatures as measured in three regions within the distribution of Rio Grande cutthroat trout (DM is 

the maximum daily value of the running 2-hour average).
Results 13

trout streams is immediately evident, with the warmest 

water temperatures typically documented in the summer 

months of July and August. Within basins, many individual 

water temperature profiles reveal streams that are similarly 

responsive and sensitive to atmospheric drivers, with 

differences in magnitude among sites likely attributable to 

stream-specific differences such as riparian shading and 

streamflow volume (figs. 3A and 3C). In strong contrast, 

Manzanita Creek demonstrated limited annual variability in 

water temperature, suggesting that the site was dominated 

by groundwater inputs compared to the other streams 

(fig. 3B). Profiles of daily maximum water temperature 

illustrated distinct diel patterns at some sites, whereas 

groundwater-dominated sites again demonstrated limited 

variability, including in the magnitude of day to day maximum 

temperature fluctuation (fig. 4).

At 46 sites containing Rio Grande cutthroat trout, 

MWATs in 2010 ranged from 7.4 to 19.0 °C and in 2011

(n=54) ranged from 6.2 to 17.6 °C (fig. 5; table 1). Maximum

daily water temperatures (maximum 2-hr average) in these

conservation populations ranged from 12.6 to 26.3 °C in 2010

and from 7.4 to 26.2 °C in 2011 (fig. 5; table 1). Potential

restoration streams displayed a similar range of water 

temperatures as currently occupied streams for both MWAT 

and daily maxima (fig. 5; table 1).

Air Temperature 

Air temperature summary metrics are presented for 

individual sites in appendix A. In general, air temperature 

maxima and minima were higher and lower than water 

temperature maxima and minima measured at a given site. 

Comparison with Colorado’s Water 

Temperature Criteria

According to Colorado’s water quality criteria for stream 

temperature, streams in which cutthroat trout are “expected to 

occur” are classified as Cold Tier 1 (Colorado Water Quality

Control Commission, 2012). The criteria for Cold Tier 1 

water temperature include both acute (daily maximum, DM)

and chronic (MWAT) threshold values. The values for the

Cold Tier 1 water temperature criteria vary seasonally, with 

winter (October–May: DM=13 °C; MWAT=9 °C) and summer

(June–September: DM=21.7 °C; MWAT=17 °C) acute and

chronic values defined. A comparison of water temperature 

metrics from our study streams with the summer Cold Tier 1 

water temperature criteria indicated that temperatures in 

some currently occupied Rio Grande cutthroat trout streams 

exceed acute daily maximum temperature (2010: 22 percent;

2011: 17 percent) and (or) chronic maximum weekly

average temperature (2010: 9 percent; 2011: 2 percent) Cold

Tier 1 water temperature criteria (fig. 5; table 1). Several

potential restoration streams were also documented to have 

temperatures that exceeded one or both Cold Tier 1 water 

temperature criteria (fig. 5; table 1).

Discharge

Of the discharge values taken at 64 sites in 2010, 58

were within Rio Grande cutthroat trout occupied habitat. 

Discharge values were taken at 103 sites in 2011, 93 of which 

were within Rio Grande cutthroat trout occupied habitat. In 

2010, discharge measurements within Rio Grande cutthroat 

trout populations ranged from 0.02 cubic feet per second 

(cfs) to 7.52 cfs (table 1). In 2011, discharge measurements

in Rio Grande cutthroat trout streams ranged from 0.01 cfs 

to 10.36 cfs. Although there was a wide range in discharge, 

the majority of the streams containing Rio Grande cutthroat 

trout streams had discharges less than 1.0 cfs (table 1). Flow

hydrographs for U.S. Geological Survey or Colorado Division 

of Water Resources monitored streamgage stations (within

or in proximity to streams containing Rio Grande cutthroat 

trout) were used for comparison of measured discharge values 

used in this study (fig. 6). Points denoted on the figures reflect

the measured discharge value at nearby stream temperature 

monitoring sites. Of note, our discharge values were

comparable to those recorded at USGS or Colorado Division 

of Water Resources gage sites, providing support that our 

point measurements were adequately timed and sufficiently 

accurate to represent baseflow conditions within these streams 

(fig. 7).
14 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

Figure 5. Summary water temperature metrics calculated from water temperature datasets collected in 2010 and 2011. Annual 2-hour 

daily maximum (DM) and maximum weekly average temperature (MWAT) are presented for each site. Gray bars represent potential/

current restoration streams, and black bars represent sites where Rio Grande cutthroat trout currently occur. Bins represent 1 degree 

Celsius (°C) (for example, 6 °C bin would represent sites with temperatures between 6 and 7 °C). Vertical dashed lines represent 

Colorado’s Cold Tier 1 acute (A and B) and chronic (C and D) water temperature criteria.
Results 15

Figure 6. Flow hydrographs for U.S. Geological Survey or Colorado Division of Water Resources monitored gage stations (within or in 

close proximity to Rio Grande cutthroat trout streams) used for comparison of measured discharge values in this study. Points reflect 

the measured discharge value at nearby stream temperature monitoring sites. Note that only Trinchera Creek, Colorado, and San 

Francisco Creek, Colo., currently contain populations of Rio Grande cutthroat trout. 
Figure 7. Measured baseflow discharge at sites within occupied Rio Grande cutthroat trout streams: A, 2010 (n = 54) and B, 2011 (n = 90). Bins refleccubic feet per second (cfs) equal to or below the value (for example, 1.0 cfs bin includes discharge values between 0.5 cfs and 1.0 cfs). Measurementtermini, important tributaries, and mainstems below the influence of important tributaries. Gray bars reflect discharges that were likely influenced by as defined by the accumulation of more than 1.3 centimeters (cm) of precipitation measured at the nearest SNOw TELemetry (SNOTEL) station on the measurement combined with 2 days prior.
References 17

Summary

At least 4 months of stream temperature data during 

summer conditions were collected within 46 populations of 

Rio Grande cutthroat trout in 2010 and 54 populations in 

2011. Summer temperatures were also documented within 

11 streams that represent potential restoration sites for the 

subspecies. We documented a large majority of streams 

containing populations of Rio Grande cutthroat trout that 

had no previous record of continual temperature records. 

When our data were evaluated in the context of the State of 

Colorado’s water temperature criteria (Cold Tier 1), some

populations appear to be at risk from high stream temperatures 

when we used biologically based acute (17–22 percent) and

chronic (2–9 percent) water quality metrics. Summer water

temperature profiles recorded at sites within current Rio 

Grande cutthroat trout habitat indicated that although the 

majority of currently occupied conservation streams have 

temperatures that fall well below these biologically based 

acute and chronic thermal thresholds, several sites may be 

at or approaching water temperatures considered stressful to 

cutthroat trout in general. Further, water temperature can affect 

the thermal suitability of potential Rio Grande cutthroat trout 

restoration sites. 

Although significant variability in baseflow was 

documented among streams, a majority of streams containing 

populations of Rio Grande cutthroat exhibited very low 

baseflow discharge. Specifically, the majority of streams 

where the subspecies has been documented to occur exhibited 

stream baseflow discharge below 1.0 cubic feet per second 

in 2010 (74 percent) and 2011 (77 percent). Anecdotal

observations of these streams indicate that low summer 

discharges result in reductions of available habitat for Rio 

Grande cutthroat trout that will likely be exacerbated during 

drought conditions. 

References

Alves, J.E., Patten, K.A., Brauch, D.E., and Jones, P.M.,

2008, Range-wide status report of Rio Grande cutthroat 

trout (Oncorhynchus clarkii virginalis)—2008: Colorado 

Division of Wildlife. (Also available at http://wildlife.state.

co.us.)

Bear, E.A, McMahon, Thomas E., and Zale, Alexander V.,

2007, Comparative thermal requirements of westslope 

cutthroat trout and rainbow trout: Implications for species 

interactions and development of thermal protection 

standards: Transactions of the American Fisheries Society 

v. 136, p. 1113–1121.

Behnke, R.J., 2002, Trout and salmon of North America: New 

York, The Free Press: New York, 359 p.

Colorado Water Quality Control Commission, 2012,

Regulation 31—The basic standards and methodologies 

for surface water: Denver, Colo., Colorado Department of 

Public Health and the Environment.

De Staso, J. III, and Rahel, F.J., 1994, Influence of water

temperature on interactions between juvenile Colorado 

River Cutthroat Trout and Brook Trout in a laboratory 

stream: Transactions of the American Fisheries Society, 

v. 123, p. 289–297.

Dunham, J., Chandler, G., Rieman, B., and Martin, D., 2005, 

Measuring stream temperature with digital data loggers—A 

user’s guide: Fort Collins, Colo., Gen. Tech. Rep. RMRSGTR-150WWW, U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, 15 p.

Dunham, J., Schroeter, R., and Rieman, B., 2003, Influence of

maximum water temperature on the occurrence of Lahontan 

cutthroat trout within streams: North American Journal of 

Fisheries Management, v. 23, p. 1042–1049.

Harrelson, C.C., Rawlins, C.L., and Potyondy, J.P., 1994, 

Stream channel reference sites—An illustrated guide to field

technique: Fort Collins, Colo., Gen. Tech. Rep. RM-245, 

U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Forest and Range Experiment Station, 61 p.

Harvey, B.C., Nakamoto, R.J., and White, J.L., 2006, Reduced 

streamflow lowers dry-season growth of rainbow trout in

a small stream: Transactions of the American Fisheries 

Society, v. 135, p. 998–1005.

Harvey, B.C., and Stewart, A.J., 1991, Fish size and habitat 

depth relationships in headwater streams: Oecologia, v. 87,

p. 336–342.

Hoerling, M., and Eischeid, J., 2007, Past peak water in the 

Southwest: Southwest Hydrology, v. 6, p. 18–19, 35.

Intergovernmental Panel on Climate Change (IPCC),

2007, Climate change 2007—Synthesis report: accessed 

November 15, 2009 at www.ipcc.ch. 

Jobling, M., 1997, Temperature and growth—Modulation of 

growth rate via temperature change, in Wood, C.M., and 

McDonald, D.G., eds., Global Warming—Implications for 

freshwater and marine fish: Cambridge University Press.

Lake, P.S., 2003, Ecological effects of perturbation by drought 

in flowing waters: Freshwater Biology, v. 48, p. 1161–1172.

Magnuson, J.J., Crowder, L.B., and Medvick, P.A., 1979, 

Temperature as an ecological resource: American Zoologist,

v. 19, no. 1, p. 331–343.

Onset Computer Corporation, 2009, HOBO U22 Water Temp

Pro v2: Document # 10366-C. 
18 Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout

Pritchard, V.L., and Cowley, D.E., 2006, Rio Grande cutthroat

trout (Oncorhynchus clarkii virginalis)—A technical 

conservation assessment: USDA Forest Service, Rocky 

Mountain Region: accessed September 15, 2008 at http://

www.fs.fed.us/r2/projects/scp/assessments. 

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow—Volume 1. Measurement of stage and

discharge: U.S. Geological Survey Water-Supply Paper 

2175, 313 p.

RGCT Conservation Team, 2009, Conservation agreement for 

Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis) 

in the states of Colorado and New Mexico: Fort Collins, 

Colo., Colorado Division of Wildlife, 24 p.

Schuett-Hames, D., Pleus, A.E., Rashin, E., and Matthews, J., 

1999, TFW Monitoring Program method manual for the 

stream temperature survey: Prepared for the Washington 

State Dept. of Natural Resources under the Timber, Fish, 

and Wildlife Agreement, 35 p. 

Soupir, M.L., Mostaghimi, S., and Mitchem, C.E., Jr., 2009, A 

comparative study of stream-gaging techniques for lowflow measurements in two Virginia tributaries: Journal of

the American Water Resources Association, v. 45, no. 1, 

p. 110–122.

Todd, A.S., Coleman, M.A., Konowal, A.M., May, M.K.,

Johnson, S., Vieira, N.K.M., and Saunders, J.F., 2008,

Development of new water temperature criteria to protect 

Colorado’s fisheries: Fisheries, v. 33, no. 9, p. 433–443.

U.S. Environmental Protection Agency (USEPA), 2004,

Wadeable stream assessment—Field operations manual: 

Washington, D.C., EPA841-B-04-004, U.S. Environmental 

Protection Agency, Office of Water and Office of Research

and Development.

U.S. Federal Register, 2008, Status review for Rio Grande 

cutthroat trout: Federal Register, v. 73, no. 94 (14 May

2008), p. 27900–27926.

Webb, B.W., Hannah, D.M., Moore, R.D., Brown, L.E., and 

Nobilis, F., 2008, Recent advances in stream and river 

temperature research: Hydrological Processes, v. 22, 

p. 902–918.

Winkle, W.V., Rose, K.A., Shuter, B.J., Jager, H.I., and

Holcomb, B.D., 1997, Effects of climatic temperature 

change on growth, survival, and reproduction of rainbow 

trout—Predictions from a simulation model: Canadian 

Journal of Fisheries and Aquatic Sciences, v. 54, 

p. 2526–2512.

Zeigler, M.P., 2012, The effects of climate change on the

future persistence of Rio Grande cutthroat trout: An 

assessment of recent climate change, thermal limits, and 

current and future stream temperature trends: Las Cruces, 

New Mexico State University, masters of science, 142 p. 

Zeigler, M.P., Todd, A.S., and Caldwell, C.C., 2012, Evidence

of recent climate change within the historic range of Rio 

Grande cutthroat trout—Implications for management and 

future persistence: Transactions of the American Fisheries 

Society, v. 141, p. 1045–1059.

Publishing support provided by

Lafayette Publishing Service Center
Zeigler and others—Water Temperature and Baseflow Discharge of Streams Throughout the Range of Rio Grande Cutthroat Trout—OFR 2013–1051