U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2015–5025

Prepared in cooperation with the U.S. Army Corps of Engineers, Albuquerque District, and the 

U.S. Fish and Wildlife Service

Physical Characteristics and Fish Assemblage Composition 

at Site and Mesohabitat Scales over a Range of Streamflows 

in the Middle Rio Grande, New Mexico, Winter 2011–12, 

Summer 2012

run

point bar

channel bar

channel bar
Cover.

1. Photograph of Christopher Braun delineating the right bank of the Rio Grande (Daniel Pearson, U.S. Geological Survey)

2. Photograph of Rio Grande silvery minnow with tagged dorsal fin (Daniel Pearson, U.S. Geological Survey)

3. Delineated, shaded, and labeled large-scale mesohabitats (Daniel Pearson, U.S. Geological Survey)

Background Image

Photograph of the Rio Grande at the Bosque del Apache I site (Daniel Pearson, U.S. Geological Survey)

3

1

2
Physical Characteristics and Fish Assemblage 

Composition at Site and Mesohabitat Scales 

over a Range of Streamflows in the Middle 

Rio Grande, New Mexico, Winter 2011–12, 

Summer 2012

By Christopher L. Braun, Daniel K. Pearson, Michael D. Porter, and J. Bruce Moring

Prepared in cooperation with the U.S. Army Corps of Engineers, Albuquerque 

District, and the U.S. Fish and Wildlife Service

Scientific Investigations Report 2015–5025

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: 2015

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

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U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

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Suggested citation:

Braun, C.L., Pearson, D.K., Porter, M.D., and Moring, J.B., 2015, Physical characteristics and fish assemblage composition at site and mesohabitat scales over a range of streamflows in the Middle Rio Grande, New Mexico, winter 

2011–12, summer 2012: U.S. Geological Survey Scientific Investigations Report 2015–5025, 90 p., http://dx.doi.

org/10.3133/sir20155025.

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

ISBN 978-1-4113-3919-4
iii

Acknowledgments

The authors would like to recognize the efforts of Jason Remshardt, Thomas Archdeacon, 

and staff with the U.S. Fish and Wildlife Service New Mexico Fish and Wildlife Conservation 

Office in Albuquerque, New Mexico, for conducting all fish assemblage surveys, maintaining 

required Federal permits to collect and handle Rio Grande silvery minnow, and making 

onsite fish identifications and counts. The authors would also like to recognize the efforts 

of Sarah Beck, Justin Reale, and staff with the U.S. Army Corps of Engineers, Albuquerque 

District for assisting with fish assemblage surveys and measuring and documenting physical 

characteristics and water-quality properties. 

The authors gratefully acknowledge the contributions of Dr. Timothy H. Bonner, Texas State 

University. Dr. Bonner was of tremendous help calculating certain fish species metrics, and 

his insights into minnow species, including Hybognathus amarus (Rio Grande silvery minnow), 

were invaluable. The time, advice, and professional expertise that he provided greatly 

improved the report.
iv
v

Contents

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

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

Background and Previous Studies ....................................................................................................4

Purpose and Scope ..............................................................................................................................5

Description of Study Area ...................................................................................................................5

Methods of Investigation..............................................................................................................................7

Selection of Sites and Streamflow Regimes ...................................................................................9

Mesohabitat Assessment....................................................................................................................9

Physical Characteristics and Water-Quality Properties of Mesohabitats................................16

Fish Assemblage Surveys of Mesohabitats ...................................................................................18

Geospatial Database..........................................................................................................................19

Physical Characteristics and Water-Quality Properties of Mesohabitats

over a Range of Streamflows.......................................................................................................20

Fish Assemblage Composition at the Site Scale ....................................................................................49

Fish Assemblage Composition at the Mesohabitat Scale ....................................................................56

Summary........................................................................................................................................................65

References....................................................................................................................................................69

Appendix 1. Sites where data were collected during previous investigations

in the Middle Rio Grande, New Mexico, 2005–8 .......................................................................75

Appendix 2. Map of sites from previous investigations in the Middle Rio Grande,

New Mexico, 2005–8......................................................................................................................76

Appendix 3. Data tables and definitions of data elements associated with the

project geospatial database.........................................................................................................77

Appendix 4. Federal Geographic Data Committee-compliant metadata record...............................85

Figures

1. Map showing historic and current geographic extent of Hybognathus

amarus (Rio Grande silvery minnow) in New Mexico and Texas.........................................3

2. Map showing sites where mesohabitats were assessed and

Middle Rio Grande Bosque Initiative reaches on the Middle Rio Grande,

New Mexico, 2011–12 ..................................................................................................................6

3. Graph showing measured daily mean discharge at U.S. Geological

Survey streamflow-gaging station 08319000 Rio Grande at San Felipe,

New Mexico, January 1, 1927–August 31, 2012 ......................................................................7

4. Graph showing measured daily mean discharge at U.S. Geological Survey

streamflow-gaging stations; November 1, 2011–August 31, 2012 ......................................10

5. Graph showing periods of streamflow and river fragmentation in the

Middle Rio Grande, New Mexico, January 1, 2011–December 31, 2012 ...........................11

6. Photographs showing overview of approach used to assess

mesohabitats in the Middle Rio Grande, New Mexico.........................................................13

7. Illustration of mesohabitat types identified in the Middle Rio Grande,

New Mexico ................................................................................................................................15

8. Schematic showing sampling patterns in mesohabitats.....................................................17
vi

9. Schematic showing simplified geospatial database data model for the

spatial and tabular mesohabitat data collected from 15 U.S. Geological

Survey sites on the Middle Rio Grande, New Mexico, winter 2011–12

and summer 2012 ........................................................................................................................21

10. Box plots showing depth and velocity in different mesohabitat types

at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12

and summer 2012 ........................................................................................................................22

11. Graphs showing area-weighted depths by mesohabitat, area-weighted

velocities by mesohabitat and measured discharge............................................................32

12. Bar graph showing area-weighted substrate composition ................................................34

13. Box plots showing temperature, dissolved oxygen, specific conductance,

and pH in different mesohabitat types at 13 sites on the Middle Rio

Grande, New Mexico, summer 2012........................................................................................35

14. Bar graph showing fish-species richness collected from 15 sites on the

Middle Rio Grande distributed among four reaches of the Middle Rio

Grande, New Mexico, winter 2011–12 and summer 2012 ....................................................57

15. Bar graph showing catch per unit effort from 15 Middle Rio Grande

sites distributed among four reaches of the Middle Rio Grande,

New Mexico, winter 2011–12 and summer 2012 ...................................................................58

16. Canonical correspondence analysis ordination biplot showing correlation

between fish species and a combination of mesohabitats and

environmental variables at 15 sites distributed among four reaches

of the Middle Rio Grande, New Mexico, winter 2011–12.....................................................59

17. Canonical correspondence analysis ordination biplot showing

correlation between fish species and a combination of mesohabitats

and environmental variables at 13 sites distributed among four reaches

of the Middle Rio Grande, New Mexico, summer 2012 ........................................................60

18. Boxplot showing fish-species richness by mesohabitat type

measured at 15 Middle Rio Grande sites distributed among four reaches

of the Middle Rio Grande, New Mexico..................................................................................62

19. Boxplots showing catch per unit effort by mesohabitat type from

15 Middle Rio Grande sites distributed among four reaches of the

Middle Rio Grande, New Mexico.............................................................................................63

20. Boxplots showing depths associated with the collection of selected

minnow species from three reaches of the Middle Rio Grande,

New Mexico, during winter 2011–12 and during summer 2012 ..........................................64

21. Boxplots showing velocities associated with the collection of

selected minnow species from three reaches of the Middle Rio Grande,

New Mexico, during winter 2011-12, and summer 2012; and collection

frequencies of Rio Grande silvery minnows as a function of velocity...............................66

22. Boxplots showing dissolved oxygen concentrations associated

with the collection of selected minnow species during summer 2012

from three reaches of the Middle Rio Grande, New Mexico..............................................67
vii

Tables

1. Physical characteristics and fish assemblage sampling sites and

sampling dates, Middle Rio Grande, New Mexico, 2011–12 .................................................8

2. Description of mesohabitat types and channel features that were

mapped on the Middle Rio Grande, New Mexico, 2011–12.................................................14

3. Area-weighted mean values of the water-quality properties measured

at 13 sites on the Middle Rio Grande, New Mexico, summer 2012 ....................................48

4. Fish species, number of individuals collected, number of species of fish,

and catch per unit effort from 15 sites distributed among four reaches

of Middle Rio Grande, New Mexico, winter 2011–12 and summer 2012 ...........................50

Conversion Factors

Inch/Pound to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Velocity

foot per second (ft/s) 0.3048 meter per second (m/s)

Flow rate

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

International System of Units 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

square meter (m2) 10.76 square foot (ft2)

Flow rate

centimeter per second 0.3937 inch per year

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

°F=(1.8×°C)+32
viii

Datum

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

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

(NAVD 88).

Supplemental Information

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 in milligrams per liter (mg/L).

Abbreviations

CCA Canonical correspondence analysis

CPUE Catch per unit effort

GIS Geographic information system

GPS Global Positioning System

MRGBI Middle Rio Grande Bosque Initiative

USGS U.S. Geological Survey
ix
Physical Characteristics and Fish Assemblage 

Composition at Site and Mesohabitat Scales over a Range 

of Streamflows in the Middle Rio Grande, New Mexico, 

Winter 2011–12, Summer 2012

By Christopher L. Braun,1 Daniel K. Pearson,1 Michael D. Porter,2 and James B. Moring1

Abstract

In winter 2011–12 and summer 2012, the U.S. Geological 

Survey (USGS), in cooperation with the U.S. Army Corps 

of Engineers, Albuquerque District and the U.S. Fish and 

Wildlife Service New Mexico Fish and Wildlife Conservation 

Office in Albuquerque, New Mexico, evaluated the physical 

characteristics and fish assemblage composition of available 

mesohabitats over a range of streamflows at 15 sites on the 

Middle Rio Grande in New Mexico. The fish assemblage 

of the Middle Rio Grande includes several minnow species 

adapted to hydrologically variable but seasonably predictable 

rivers, including the Hybognathus amarus (Rio Grande 

silvery minnow), a federally listed endangered species. 

Gaining a better understanding of habitat usage by the Rio 

Grande silvery minnow was the impetus for studying physical 

characteristics and fish assemblages in the Middle Rio Grande 

during different streamflow conditions. Data were collected 

at all 15 sites during winter 2011–12 (moderate streamflow), 

and a subset was collected at the 13 most downstream sites 

in summer 2012 (low streamflow). Sites were grouped into 

four river reaches separated by diversion dams listed in 

downstream order (names of the diversion dams are followed 

by short names of the sites nearest each dam in parentheses, 

listed in downstream order): (1) Cochiti (Peña Blanca), 

(2) Angostura (Bernalillo, La Orilla, Barelas, Los Padillas), 

(3) Isleta (Los Lunas I, Los Lunas II, Abeytas, La Joya, Rio 

Salado), and (4) San Acacia (Lemitar, Arroyo del Tajo, San 

Pedro, Bosque del Apache I, and Bosque del Apache II). 

Stream habitat was mapped in the field by using a geographic 

information system in conjunction with a Global Positioning 

System. Fish assemblage composition was determined 

during both streamflow regimes, and fish were collected by 

seining in each mesohabitat where physical characteristic data 

(depth, velocity, dominant substrate type and size, and percent 

embeddedness) and water-quality properties (temperature, 

dissolved oxygen, specific conductance, and pH; during 

summer 2012 only) were measured.

Nineteen species of fish were collected among the 15 sites 

and four reaches over both sampling periods; 10 of these 

19 species are introduced. Fish-species richness (total number 

of fish species collected at each site during each sampling 

event) among sites that were sampled during both sampling 

periods ranged from 6 at Rio Salado to 12 at La Orilla. Fish 

were most abundant at the Lemitar site (1,786 individuals) 

and least abundant at the San Pedro site (275 individuals). The 

native Cyprinella lutrensis (red shiner) was the most abundant 

species collected among all of the sites, accounting for about 

42 percent of fish collected. Fish-species richness and catch 

per unit effort (CPUE) were higher (or equivalent) at all sites 

during summer 2012 compared to winter 2011–12.

The relations between fish assemblage composition 

(that is, total abundance, which refers to the number of 

individuals of each species that were collected) and selected 

environmental variables (physical characteristic data collected 

at the mesohabitat scale [depth, velocity, and substrate particle 

size], and mesohabitat types) were explored by using canonical 

correspondence analysis. Environmental variables explained 

8 percent (p=0.48) of the variability in the Middle Rio Grande 

fish assemblage during winter 2011–12, and Rio Grande silvery 

minnow were weakly associated with sand substrates, relatively 

moderate velocities (qualitative descriptors are derived from 

synthetic gradients extracted from CCAs), and relatively 

shallow depths. Environmental variables explained 14 percent 

(p < 0.01) of the variability in the Middle Rio Grande fish 

assemblage during summer 2012, when Rio Grande silvery 

minnow were associated with run mesohabitats, relatively high 

velocities, sand substrates, and relatively moderate depths.

1

U.S. Geological Survey.

2

U.S. Army Corps of Engineers.
2 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

The mean fish-species richness was greater in summer 

2012 than in winter 2011–12 for each mesohabitat type, and the 

overall fish-species richness across all mesohabitat types was 

0.62 during winter 2011–12, compared to 1.49 during summer 

2012. The highest mean CPUE during winter 2011–12 was in 

isolated pools (54.3 fish per 100 square meters [m2]), whereas 

the lowest was in flats (18.9 fish per 100 m2). Ranges in CPUE 

were higher in summer 2012 relative to winter 2011–12 in 

each mesohabitat type sampled. As in winter 2011–12, the 

highest mean CPUE during summer 2012 was in isolated pools 

(233 fish per 100 m2), whereas the lowest was in flats (29.6 fish 

per 100 m2). Overall mean CPUE per mesohabitat across all 

mesohabitat types was 29.1 fish per 100 m2 during winter 2011–

12 compared to 85.3 fish per 100 m2 during summer 2012.

Four species of minnows (red shiner, Rio Grande 

silvery minnow, Pimephales promelas [fathead minnow], and 

Platygobio gracilis [flathead chub]) were selected to compare 

preferred mesohabitat characteristics because all are smallbodied minnows and because more than 200 individuals of 

each of these species were collected. Red shiner were collected 

across the largest range of depths in both winter 2011–12 

(0.02–4.31 feet [ft]) and summer 2012 (0.05–3.4 ft), as well as 

the largest range of velocities (0.0–4.31 feet per second [ft/s]) 

during winter 2011–12 among the four minnow species of 

interest. Rio Grande silvery minnow occurred in the narrowest 

range of depths (0.30–2.1 ft) during summer 2012, as well 

as the narrowest range of velocities in both winter 2011–12 

(0.0–3.18 ft/s) and summer 2012 (0.02–1.51 ft/s).

Water-quality properties were only collected during 

summer 2012, when low-streamflow conditions existed 

and water-quality properties were thought to be potentially 

most limiting to aquatic life. Area-weighted mean water 

temperatures tended to be higher at the sites that were sampled 

in August 2012 (25.57 degrees Celsius [°C]) compared to 

June 2012 (24.61 °C). The highest area-weighted mean water 

temperature at a given site (29.03 °C) was measured at the 

Lemitar site on August 7, 2012, coincident with the lowest 

measured discharge (4.13 cubic feet per second [ft3/s]). Areaweighted mean dissolved oxygen concentrations tended to be 

lower in August (7.46 milligrams per liter [mg/L]) compared to 

June (8.33 mg/L). The highest area-weighted mean dissolved 

oxygen concentration (9.13 mg/L) was measured at the Lemitar 

site on August 7, 2012, and the lowest area-weighted mean 

dissolved oxygen concentration (6.23 mg/L) was measured 

at the Los Padillas site on August 10, 2012. Area-weighted 

specific conductance in the sites upstream from La Joya did 

not exceed 400 microsiemens per centimeter (μS/cm) at 25 °C, 

whereas the area-weighted mean specific conductance at La 

Joya (837 μs/cm at 25 °C), Rio Salado (857 μs/cm at 25 °C), 

and Lemitar (1,300 μs/cm at 25 °C) were all well above the 

average of the area-weighted means for the 10 remaining 

sites (433 μs/cm at 25 °C). Lower area-weighted mean pH 

values were measured at the 3 sites in and near Albuquerque 

(La Orilla, Barelas, and Los Padillas—7.98, 8.08, and 7.81, 

respectively) compared to any of the 10 remaining sites, which 

had an overall mean pH of 8.44.

Introduction

The Rio Grande begins in Colorado (fig. 1), flows 

through New Mexico, and becomes the border between 

Texas and Mexico before emptying into the Gulf of Mexico. 

It is the second longest river in North America (Schmidt 

and others, 2003). Much of the Rio Grande Basin is arid to 

semiarid, and native aquatic organisms including Hybognathus 

amarus (Rio Grande silvery minnow) are adapted to a natural 

streamflow regime that includes seasonal floods. Schmidt and 

others (2003) explain that from the headwaters in Colorado 

to Presidio, Tex., the natural streamflow regime of the Rio 

Grande is snowmelt driven, with seasonal floods between 

April and July in response to snowmelt in the headwaters. 

Historically, streamflow in the Rio Grande Basin fluctuated 

between peak streamflow (typically from snowmelt runoff 

in the northern part of the basin and rainfall runoff in the 

southern part of the basin) (U.S. Army Corps of Engineers 

and others, 2007) and periods of low streamflow characterized 

by fragmentation, when some segments of the Rio Grande 

would go dry (Tetra Tech, Inc., 2014). Beginning in the early 

1900s, the construction of impoundments for flood control and 

irrigation, diversion channels, and canals (collectively referred 

to as “river training actions”) altered the natural streamflow 

regime and geomorphic characteristics of the river (Makar 

and AuBuchon, 2012). River training structures (man-made 

structures designed and built within a river reach to alter the 

streamflow and sediment response of a river (U.S. Army Corps 

of Engineers, 2014) followed in the 1940s, including Kelner 

Jetties (jetty jacks) and levees and freeboard dikes (U.S. 

Bureau of Reclamation, 2012; The Texas Tribune, 2014).

The Middle Rio Grande, defined for the purpose of this 

report as the 280-kilometer (km) reach of the Rio Grande from 

Cochiti Dam downstream to Elephant Butte Reservoir, is in an 

arid part of the Rio Grande Basin dependent on inflows from 

upstream (fig. 1). Prior to the construction of Cochiti dam 

in 1975 (U.S. Bureau of Reclamation, 2012), large seasonal 

floods from snowmelt runoff in Colorado and New Mexico 

would occur most years on the Middle Rio Grande (Schmidt 

and others, 2003). Since the construction of Cochiti Dam, 

seasonal peaks in streamflow in the Middle Rio Grande from 

snowmelt runoff upstream have been much smaller. Makar 

and Aubuchon (2012, p. 55–56) explain how the natural 

streamflow regime has changed:

The current hydrologic regime has limited flood 

magnitude and modified flood frequency. The frequencies have changed in two ways: large peaks are 

less frequent because of flood management, while 

smaller flood peaks and low flows are more frequent 

because water storage and release for irrigation 

and water is pumped from the Low Flow Conveyance Channel (LFCC) to provide minimum flows 

for habitat. Consequently, the river system does not 

experience the tremendous peaks or very low flows 

of the past.
Introduction 3

Lake

Sumner

Red Bluff

Reservoir

Amistad

Reservoir

Falcon Reservoir

Elephant Butte

Reservoir

Caballo

Reservoir

Cochiti

Lake

Rio Chama

River

Pe cos River

Rio Grande

GULF OF

MEXICO

BIG BEND

NATIONAL PARK

BIG BEND RANCH

STATE PARK

TEXAS

COLORADO NEW MEXICO

Rio Grande

River Basin

Study area

COCHITI DAM

ELEPHANT BUTTE DAM

MULATO DAM

FOSTER’S WEIR

Albuquerque

Santa

Rosa

Socorro

Roswell

El Paso

Presidio

Pecos

Del Rio

Laredo

0 50 100 MILES

0 50 100 KILOMETERS

laf15-CSSJ00-0678_fig 01

100°0'

100°0'

105°0'

105°0'

35°0'

30°0'

30°0'

EXPLANATION

Historic distribution

Current (2015) natural distribution

 (U.S. Fish and Wildlife Service, 2010)

Current (2015) reintroduced distribution (U.S. Fish

 and Wildlife Service, 2010)—Based on

 reintroduction initiated in December 2008

Base modified from U.S. Geological Survey

1:2,000,000-scale digital data

Transverse Mercator Zone 13 projection

North American Datum of 1983 

TEXAS

NEW MEXICO

MEXICO

Figure 1. Historic and current geographic extent of Hybognathus amarus (Rio Grande silvery minnow) in New Mexico and Texas.
4 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Makar and Aubuchon (2012, p. 161) further explain that 

the “lower [part] of the Middle Rio Grande [upstream from 

Elephant Butte Reservoir] contains several drainages, which 

can contribute significant flows during local thunderstorms.” 

Localized flooding can result from large thunderstorms. 

During floods, streamflow might briefly overtop the banks, but 

more typically streamflow remains within the stream channel, 

filling parts of the channel that are typically dry for extended 

periods, providing additional habitat to a wide range of species 

including native fish (Tetra Tech, Inc., 2014).

The fish assemblage of the Middle Rio Grande contains 

several minnow species adapted to hydrologically variable 

but seasonably predictable rivers, including the Rio Grande 

silvery minnow (Medley and Shirey, 2013). Gaining a 

better understanding of habitat usage by the Rio Grande 

silvery minnow, a federally listed endangered species, was 

the impetus for studying physical characteristics and fish 

assemblages in the Middle Rio Grande during different 

streamflow conditions. 

The historical range of the Rio Grande silvery minnow 

was 4,000 km in the Rio Grande and the Pecos River Basins 

(fig. 1) (U.S. Fish and Wildlife Service, 2010). Natural 

populations of the Rio Grande silvery minnow currently 

(2015) are only found in the 280-km Middle Rio Grande reach 

of the Rio Grande. The once common Rio Grande silvery 

minnow was federally listed as an endangered species in 1994 

(U.S. Fish and Wildlife Service, 1994). In addition to the 

natural population in the Middle Rio Grande, an experimental, 

reintroduced population of the Rio Grande silvery minnow 

is found in the Big Bend (300 km) reach of the Rio Grande 

that begins at Mulato Dam in Texas, flows through Big Bend 

National Park, and continues downstream to Foster’s Weir 

(fig. 1). In 2008, the U.S. Fish and Wildlife Service began 

efforts to restore the Rio Grande silvery minnow to this 

part of its former historical range (U.S. Fish and Wildlife 

Service, 2010; Moring and others, 2014). Throughout its 

historical range, Rio Grande silvery minnow decline has been 

attributed to modifications of the natural streamflow regime, 

channel drying, reservoir construction, stream channelization, 

declining water quality, and interactions with nonnative 

fish (Cook and others, 1992; Edwards, 2005; U.S. Fish and 

Wildlife Service, 2010).

 Understanding habitat availability and use by Rio 

Grande silvery minnow is an essential element for the 

Recovery Implementation Program to be successful (Galat 

and others, 2001; Middle Rio Grande Endangered Species 

Collaborative Program, 2013). Because habitat needs vary 

throughout a species’ life cycle, and because the size and 

distribution of habitats can change over time in response 

to streamflow, it was important to assess fish habitat at the 

mesohabitat scale. Mesohabitats are visually distinct units 

of habitat within a stream with apparent uniformity and 

similar depth, velocity, slope, substrate, and cover (Pardo and 

Armitage, 1997; Parasiewicz, 2001; Parasiewicz and Dunbar, 

2001). A “mesohabitat-scale” assessment of available habitat 

in relation to streamflows is considered by many ecologists 

and fluvial geomorphologists to be critical for the development 

of practical tools in river management (Harper and Everard, 

1998; Newson and Newson, 2000). 

Moring and others (2014, p. 4) explain the importance 

of assessing habitat for different streamflow conditions and 

the usefulness of assessing fish assemblage composition (the 

different species of fish coexisting in a habitat) in streams 

supporting or believed capable of supporting the sustainable 

populations of Rio Grande silvery minnow:

Because habitat needs vary throughout a species’ 

life cycle, and because the size and distribution of 

habitats can change over time in response to streamflow, it was important to assess fish habitat at the 

mesohabitat scale. *** Because the assemblage of 

mesohabitat types is stable, aquatic organisms have 

adapted to the physical characteristics and temporal 

dynamics of the mesohabitats with which they are 

associated (Southwood, 1988), meaning that the 

mesohabitat scale is often the ideal scale for evaluating fish habitat. 

The relation between the amount of streamflow and 

habitat for Rio Grande silvery minnow and similar species of 

fish in the Middle Rio Grande is not well understood. To better 

understand the spatial extent of available mesohabitats over 

a range of streamflows, the U.S. Geological Survey (USGS), 

in cooperation with the U.S. Army Corps of Engineers, 

Albuquerque District and the U.S. Fish and Wildlife Service 

New Mexico Fish and Wildlife Conservation Office in 

Albuquerque, N. Mex., evaluated the physical characteristics 

and fish assemblages during 2011–12 at 15 sites on the Middle 

Rio Grande in New Mexico, in the reach downstream from 

Cochiti Dam to Elephant Butte Reservoir. 

Background and Previous Studies

Rio Grande silvery minnow are small-bodied minnows 

(Sublette and others, 1990) with silver coloration (preserved 

specimens are brown to olive [dorsal] and white [ventral]). 

Rio Grande silvery minnow adults use low-velocity habitats 

(Dudley and Platania, 1997; Bovee and others, 2008) with 

a silty (fine-sized silt and clay particles less than 0.062 

millimeters [mm] in size) or sandy (sand-sized particles 

greater than 0.062 to 2 mm in size) (Wentworth, 1922; Guy, 

1969) substrate. Rio Grande silvery minnow are broadcast 

spawners that produce thousands of semibuoyant eggs 

(Cowley and others, 2005; Medley and Shirey, 2013). During 

the spring, extensive drift of eggs has been documented during 

low volume pulses of streamflow (Dudley and Platania, 2007), 

whereas recruitment is associated with the availability of low 

water velocity (backwater) habitats used by larval and juvenile 

Rio Grande silvery minnows (Pease and others, 2006). 

Previous habitat studies (apps. 1 and 2) have used a 

hydraulic approach to: represent the range of hydrologic and 

geomorphologic variation within the Middle Rio Grande 

and Rio Chama (U.S. Army Corps of Engineers and others, 
Introduction 5

2007); assess Rio Chama and Rio Grande fish habitat quality 

(upstream from Cochiti Lake; Buntjer and Remshardt, 2005); 

incorporate geomorphic patterns with diversion dams and 

irrigation returns (Remshardt and Tashjian, 2003); and focus 

on specific sites (Torres and others, 2008). In addition, Bovee 

and others (2008) applied the Instream Flow Incremental 

Methodology (Bovee and others, 1998) toward understanding 

streamflow relationships for fish habitat management in a 

short reach. Fish sampling, often done in concert with habitat 

suitability assessments, has been done by using mesohabitat 

classification (Dudley and Platania, 1997) as a criterion for 

fish population monitoring and assessment (Dudley and others, 

2012, 2013).

Mesohabitat-scale mapping provides information 

on habitat area as a function of alterations in streamflow, 

channel planform, and other activities (Parasiewicz, 2001). 

Development of an integrated habitat restoration strategy that 

achieves a population-level response requires understanding 

mesohabitat use by Rio Grande silvery minnows and 

quantifying the area of available habitat for all life stages 

(Middle Rio Grande Endangered Species Collaborative 

Program, 2013). 

Mesohabitat use by Rio Grande silvery minnows along 

with stream depth, velocity, and substrate (Dudley and 

Platania, 1997) have been the basis for numerous studies 

(Dudley and others, 2012, 2013; Moring and others, 2014); 

however, information on the spatial extent of available 

mesohabitats over a range of streamflows throughout the 

Middle Rio Grande is sparse (Remshardt and Tashjian, 2003). 

This report is intended to build on previous investigations that 

were done to understand habitat use by Rio Grande silvery 

minnow. The availability of functional habitat is essential 

for maintaining viable fish populations (Lapointe and others, 

2013). The spatial extent, physical characteristics, and use of 

mesohabitat types for different streamflows were obtained 

for all fish species present at selected sites on the Middle 

Rio Grande during 2011–12. This information was collected 

in support of ongoing efforts by the Middle Rio Grande 

Endangered Species Collaborative Program to promote 

sustainable populations of Rio Grande silvery minnow.

Purpose and Scope

The purpose of this report is to describe mesohabitats and 

their use by fish during different seasonal streamflow regimes 

(winter 2011–12 and summer 2012) at 15 sites on the Middle 

Rio Grande in New Mexico (fig. 2); winter in this report 

refers to November 2011 through February 2012, and summer 

refers to June through August 2012. Data were collected at 

all 15 sites during winter 2011–12 (moderate streamflow), 

and a subset was collected at the 13 most downstream sites 

in summer 2012 (low streamflow). Physical characteristic 

and fish assemblage data were collected and assessed at the 

mesohabitat scale during the winter and summer sampling 

periods. Comparisons of fish assemblage data within and 

among the 15 sites are made by analyzing total abundance 

data, species richness information, relative abundance, total 

fish density, fish-species density, and other metrics. Statistical 

analysis of fish data includes use of a multivariate statistical 

analysis, the canonical correspondence analysis (CCA). 

Water-quality properties (dissolved oxygen, pH, specific 

conductance, and temperature) measured in summer 2012 

(a period characterized by relatively low streamflow) are 

compared among sites because these properties are considered 

most crucial for sustaining aquatic biota. All of the data that 

were collected and used for analysis are in the geospatial 

database included with this report.

Description of Study Area

Currently (2015), the Middle Rio Grande is a highly 

regulated system influenced by multiple storage and flood 

control reservoirs, several diversion dams, and almost 

1,500 km of irrigation canals and drainages between Cochiti 

Dam and Elephant Butte Reservoir. Dams, diversions, and 

canals have not altered the preregulation seasonal streamflow 

pattern (fig. 3) but have dampened the magnitude and 

duration of extreme streamflow events (U.S. Army Corps 

of Engineers and others, 2007) and have led to increased 

stream fragmentation, including extended periods with no 

streamflow downstream from Albuquerque between river mile 

168 (near the Los Lunas I site) and river mile 73 (about 2 

miles downstream from the Bosque del Apache II site) during 

summer to early fall irrigation (Tetra Tech, Inc., 2014) (sites 

are referred to throughout this report by their short names, as 

shown in table 1).

By summarizing the work of others, Padilla and Baird 

(2010) explain that the Middle Rio Grande is estimated to 

have been aggrading during the past 11,000 to 22,000 years 

(Leopold and others, 1964; Hawley and others, 1976) 

because inflows contributed more sediment than the river 

could transport (Crawford and others, 1993). The historically 

large sediment load of the Middle Rio Grande resulted in 

aggradation of the channel and flood plain (Happ, 1948; 

Leopold and others, 1964; Scurlock, 1998; Makar and 

AuBuchon, 2012). Historically, the Middle Rio Grande 

alternated between narrow channels in canyon-bound 

reaches and wider, braided, sandy channels between the 

canyon reaches (Lagasse, 1980; Scurlock, 1998; Makar and 

Massong, 2009; Makar and AuBuchon, 2012). As a result of 

river training actions during the past 100 years, the channel 

planform of the Middle Rio Grande changed from a relatively 

wide, braided, and aggrading sand-bed channel to a relatively 

narrow, single-threaded, and mostly degrading channel that is 

dominated by a gravel bed through much of its length (Makar 

and AuBuchon, 2012). In addition to reductions in sediment 

supply, narrowing in the width of the Rio Grande has been 

attributed to changes in peak spring flows caused by upstream 

flood control, channelization activities, and other river 

training actions used to manage flows for irrigation purposes 
6 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

NEW MEXICO

Study area

0 20 40 MILES

0 20 40 KILOMETERS

Base modified from U.S. Geological Survey

1:1,000,000-scale digital data

Transverse Mercator Zone 13 projection

North American Datum of 1983 

laf15-CSSJ00-0678_fig 02

EXPLANATION

Middle Rio Grande Bosque Initiative

 (MRGBI) reach names (table 1)

 Cochiti reach

 Angostura reach

 Isleta reach

 San Acacia reach

Map identifiers followed by short

 names for sampling sites (table 1)

 PNB - Peña Blanca

 BRN - Bernalillo

 LOR - La Orilla

 BAR - Barelas

 PAD - Los Padillas

 LL1 - Los Lunas I

 LL2 - Los Lunas II

 ABY - Abeytas

 LJY - La Joya

 RSL - Rio Salado

 LEM - Lemitar

 ATJ - Arroyo del Tajo

 SPD - San Pedro

 BA1 - Bosque del Apache I

 BA2 - Bosque del Apache II

Sampling site and map identifier (table 1)

Lower San Juan Riverside Drain

U.S. Geological Survey streamflow-gaging station

 and station number

PNB

08317400

£¤66

£¤285

£¤285

£¤380

£¤60

£¤550

£¤64

UV96

VU55

UV549

UV6

UV107

£¤550

*-25

*-40

-*25 Cochiti reach

Angostura reach

Isleta reach

San Acacia reach Rio

Grande

Jemez Ri ver

Rio Pu e rco

Al amosa C reek

Arroyo Comanche

Rio Galli n a

Jemez River

Rio Salado

Rio Cham a

El Rito

Galiste o Cre ek

Rio Tusas

Santa Fe Ri v er

Elephant Butte

Reservoir

BOSQUE DEL APACHE

NATIONAL WILDLIFE REFUGE 

SAN ALAMEDA BRIDGE

Arroyo del Tajo

Lower San Juan

Riverside Drain

LL1

BRN

SPD

LEM

LJY

ATJ

PAD

ABY

RSL

PNB

BA1

LOR

BAR

BA2

LL2

08317400

08319000

08329918 08329928

08330000

08330875

08331160

08331510

08355050

08355490

see figure 3 for 

long-term example 

streamflow record

08353000

ANGOSTURA

DIVERSION

DAM

COCHITI

DAM

ISLETA

DIVERSION

DAM

SAN ACACIA

DIVERSION

DAM

JEMEZ

CANYON

DAM

Los Lun s

Tierra Amarilla

Bernalillo

Los Alamos

Alameda

Bosque Farms

Escondida

Los Padillas

La Joya

San Acacia

San Antonio

Lemitar

Santa Fe

Albuquerque

a

Socorro

107°30'

107°00' 106°30' 106°00'

36°30'

35°30'

35°00'

34°30'

34°00'

33°30'

36°00'

SANDOVAL

COUNTY

BERNALILLO

COUNTY

VALENCIA

COUNTY

SOCORRO

COUNTY

RIO ARRIBA

COUNTY

SANTA FE

COUNTY

LOS ALAMOS

COUNTY

Figure 2. Sites where mesohabitats were assessed and Middle Rio Grande Bosque Initiative reaches on the Middle Rio Grande, New 

Mexico, 2011–12.
Methods of Investigation 7

laf15-CSSJ00-0678_fig 03

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Daily mean discharge, in cubic feet per second

Year

25,000

20,000

15,000

10,000

5,000

0

Figure 3. Measured daily mean discharge at U.S. Geological Survey streamflow-gaging station 08319000 Rio Grande at San Felipe, 

New Mexico, January 1, 1927–August 31, 2012. 

(Makar and AuBuchon, 2012). Padilla and Baird (2010, p. 1) 

describe an exception in which the Middle Rio Grande is still 

aggrading, not because of natural flow conditions, but rather 

as a result of Elephant Butte Reservoir filling to capacity and 

slowing stream velocities, noting “Elephant Butte Reservoir 

filled to capacity in 1985. This led to delta sediments being 

deposited (aggradation) in the channel for a distance of about 

40 miles upstream [from] the full reservoir pool location.”

Prior to becoming a highly regulated system, the Rio 

Grande conveyed the sixth largest mean sediment load of 

any river in North America (Schmidt and others, 2003). 

Sediment supply in the Rio Grande is affected by land-use 

practices and natural cycles of erosion and deposition (Vogt, 

2003) and water management (Makar and AuBuchon, 2012), 

but Cochiti Dam has the largest effect on sediment supply in 

the Middle Rio Grande. In addition to controlling the water 

discharge, Cochiti Dam traps virtually the entire sediment 

load that would naturally enter the Middle Rio Grande reach 

(Richard, 2001). Differences in sediment supply and sediment 

transport capacity result in changes to the channel planform 

(Makar and AuBuchon, 2012). In degrading channels, the loss 

of bed sediment (streambed downcutting) and transition from 

sand to gravel beds are common because the sediment load 

is smaller than the transport capacity; channel bed and bank 

erosion allows the stream to regain at least part of its sediment 

load (Kondolf, 1997). Between 1935 and 1989, the channel 

area of Middle Rio Grande decreased by about 50 percent 

(Crawford and others, 1993). Over this period, the typical 

flood-plain width was reduced from more than 9,000 meters 

(m) to as small as 2,000 m. Conveyance capacity of the Rio 

Grande was reduced to less than 7,000 cubic feet per second 

(ft3

/s) in the more narrow reaches, compared to approximately 

42,000 ft3

/s in broader reaches (Crawford and others, 1993). 

Vegetated bars split the channel at high streamflows, creating 

an anastomosing channel form, a river pattern “consisting 

of multiple channels separated by islands which are usually 

excised from the continuous flood plain and which are large 

relative to the size of the channels” (Knighton and Nanson, 

2000, p. 101). 

Methods of Investigation

The wetted area, physical characteristics, and fish 

assemblage of river mesohabitats were characterized within 

a 1-km length of stream channel at each site. Fifteen sites 

distributed along the Middle Rio Grande were selected 

starting about 3 km downstream from Cochiti Dam and 

ending about 40 km upstream from Elephant Butte Reservoir 

(table 1, fig. 2). Sites were grouped into four river reaches 

separated by diversion dams. In downstream order, the names 

of the diversion dams followed by short names of the sites 

(in parentheses) were Cochiti (Peña Blanca), Angostura 

(Bernalillo, La Orilla, Barelas, Los Padillas), Isleta (Los Lunas 

I, Los Lunas II, Abeytas, La Joya, Rio Salado), and San Acacia 

(Lemitar, Arroyo del Tajo, San Pedro, Bosque del Apache I, 

and Bosque del Apache II). The Cochiti, Angostura, and Isleta 

reaches are bound by upstream and downstream diversion 

dams (fig. 2), whereas there is a diversion dam at the upstream 

boundary of the San Acacia reach, but the downstream 

boundary of the reach is the upstream extent of Elephant Butte 

Reservoir. Stream habitat was mapped in the field by using a 

geographic information system (GIS) in conjunction with a 

Global Positioning System (GPS). The four reaches delineated 

in this report are also being assessed as part of the Middle 
Table 1. Physical characteristics and fish assemblage sampling sites and sampling dates, Middle Rio Grande, New Mexico, 2011–12. [MRGBI, Middle Rio Grande Bosque Initiative; ft3/s, cubic feet per second; --, no data were collected during indicated time period] MRGBI reach names Site name U.S. Geological Survey station number Short name Map identi- fier (fig. 2) River mile Flow regime Moderate streamflow 

Date Dis- charge2 (ft3/s) Date Dis- charge2 (ft3/s) 

Map- ping Fish and aquatic habitat1 Map- ping Fish and aquatic habitat1 

Cochiti Rio Grande near Peña Blanca, N. Mex. 353330106213500 Peña Blanca PNB 227.5 Nov. 10 Nov. 11 552 -- -- -- 

Angostura Rio Grande downstream from Highway 550 at Bernalillo, N. Mex. 351848106333400 Bernalillo BRN 203.6 Nov. 11 Nov. 12 570 -- -- -- 

Angostura Rio Grande upstream from Mon- tano Road northwest at Albu- querque, N. Mex. 350859106402600 La Orilla LOR 189.0 Nov. 16 Nov. 17 746 -- -- -- 

Angostura Rio Grande upstream from Highway 314 at Albuquerque, N. Mex. 350432106400500 Barelas BAR 183.0 Nov. 9 Nov. 10 3850 -- -- -- 

Angostura Rio Grande upstream from Interstate Highway 25 near Los Padillas, N. Mex. 345732106410800 Los Padillas PAD 173.0 Nov. 15 Nov. 16 851 -- -- -- 

Isleta Rio Grande upstream from High- way 6 at Los Lunas, N. Mex. 344852106424200 Los Lunas I LL1 162.5 Nov. 12 Nov. 14 749 -- -- -- 

Isleta Rio Grande near Los Chavez, N. Mex. 344457106443300 Los Lunas II LL2 157.0 Nov. 14 Nov. 15 31,050 -- -- -- 

Isleta Rio Grande upstream from High- way 60 near Contreras, N. Mex. 342644106481300 Abeytas ABY 133.0 Nov. 28 Nov. 29 940 -- -- -- 

Isleta Rio Grande near La Joya, N. Mex. 341842106511100 La Joya LJY 122.0 Nov. 29 Nov. 30 991 -- -- -- 

Isleta Rio Grande downstream from Arroyo Rosa de Castillo, San Acacia, N. Mex. 341542106520700 Rio Salado RSL 117.5 Nov. 30 Dec. 1 970 -- -- -- 

San Acacia Rio Grande near Lemitar, N. Mex. 341044106530300 Lemitar LEM 109.0 Dec. 1 Dec. 2 921 -- -- -- 

San Acacia Rio Grande downstream from Arroyo del Tajo near Socorro, N. Mex. 340215106515500 Arroyo del Tajo ATJ 97.0 Dec. 1 Dec. 3 870 -- -- -- 

San Acacia Rio Grande downstream from Hwy 380 near San Antonio, N. Mex. 335403106505800 San Pedro SPD 86.5 Dec. 3 4Dec. 6 857 Feb. 6 Feb. 7 -- 

San Acacia Rio Grande north of Bosque del Apache, San Antonio, N. Mex. 335229106505800 Bosque del Apache I BA1 84.5 -- -- -- Feb. 7 Feb. 8 633 

San Acacia Rio Grande at Bosque del Apache near San Antonio, N. Mex. 334833106512200 Bosque del Apache II BA2 78.0 Dec. 6 -- -- Feb. 8 Feb. 9 588 

1Includes instantaneous discharge measurements, in most cases, and water-quality property measurements at low streamflow. 2Instantaneous discharge measured between 9:00 a.m. and 1:00 p.m. during fish and aquatic habitat data collection. 3Mean daily discharge from nearest streamflow-gaging station upstream from the site. 4Fish were not collected on this date.
Methods of Investigation 9

Rio Grande Bosque Initiative (MRGBI). The MRGBI “is an 

ongoing, congressionally supported, interagency ecosystem 

management effort to coordinate activities related to the 

ecological restoration and management of the Middle Rio 

Grande” (U.S. Fish and Wildlife Service, 2014a, p. 1).

Selection of Sites and Streamflow Regimes

To help build on previous studies, 13 of the 15 sites 

where data were collected for this study were at the same 

locations where data were collected in previous Rio Grande 

aquatic habitat studies (table 1, app. 1). The Upper Rio Grande 

Water Operations Study characterized geomorphologic 

variation in the Middle Rio Grande and the Rio Chama (U.S. 

Army Corps of Engineers and others, 2007). The U.S. Fish 

and Wildlife Service study by Remshardt and Tashjian (2003) 

was based on a tiered approach established by the U.S. Bureau 

of Reclamation and Bosque Hydrology Group (U.S. Fish and 

Wildlife Service, 2014b). The three tiers for selecting sites 

were fluvial geomorphology (first), hydrological reaches 

delineated by diversion dams (second), and local influence of 

arroyos and irrigation outfalls (third) (Remshardt and Tashjian, 

2003). The U.S. Fish and Wildlife Service also revisited the 

Peña Blanca site by using similar methods (Torres and others, 

2008). The USGS selected three sites to estimate habitat 

upstream from San Acacia Diversion Dam as a function of 

streamflow from the Lower San Juan Riverside Drain (Bovee 

and others, 2008). One habitat restoration site was included 

in the study (Los Lunas II; Kissock, 2011), along with an 

additional site proposed by Bosque del Apache National 

Wildlife Refuge (Bosque del Apache II).

During this study, 13 of the 15 sites were assessed 

under two different seasonal streamflow regimes during 

winter 2011–12 and summer 2012 (table 1, fig. 4); the two 

remaining sites (Peña Blanca and Bernalillo) were only 

assessed in winter 2011–12. Mesohabitat assessments were 

completed at differing seasonal streamflow regimes to 

evaluate variability in mesohabitat wetted area and associated 

differences in the occurrence and distribution of fish among 

sites and mesohabitat types. The original intent of the study 

was to complete the assessments during moderate streamflow 

conditions in winter 2011–12 and during a period of higher 

streamflow conditions from snowmelt runoff in the late spring 

to early summer of 2012; however, the lack of appreciable 

runoff during late spring to early summer of 2012 (fig. 4 

compared to prior years on fig. 3) resulted in lower summer 

streamflows compared to what was anticipated. Therefore, 

mesohabitats were assessed during a period of moderate 

winter streamflow ranging from 552 to 1,050 ft3

/s (table 

1, fig. 4) between November 2011 and February 2012 and 

during a period of low summer streamflow ranging from 4.13 

to 430 ft3/s between June and August 2012 (table 1; fig. 4). 

The low streamflow in the summer of 2012 resulted in an 

opportunity to assess fish habitat and assemblages during a 

period of relative extremes in certain environmental variables. 

Water quality tends to be lower, and mesohabitats are less 

available during periods of low streamflow compared to 

periods with higher streamflow.

The Middle Rio Grande was flowing in all reaches where 

the sites were located during the winter 2011–12 sampling 

period (figs. 5A and 5B); however, because of the potential for 

periods of stream fragmentation at some sites in the summer 

of 2012, the sampling order in summer 2012 was changed 

relative to the sampling order in winter 2011–12. In winter 

2011–12, sites were sampled generally from upstream to 

downstream, whereas in summer 2012, sites were sampled 

in an order that would ensure that all sites were flowing at 

the time of sampling. The reordered sampling facilitated the 

assessment of as many mesohabitats as possible, as well as the 

measurement of physical characteristics and sampling of fish 

during lower streamflow conditions. Those sites that were at 

the greatest risk of drying were visited in early June 2012, and 

those sites that were expected to have streamflow throughout 

the summer were visited in August 2012 (table 1, fig. 5B). 

Mesohabitat Assessment

The approach used to assess mesohabitats in the Middle 

Rio Grande, N. Mex., was modified from Parasiewicz and 

Dunbar (2001). Mesohabitat assessment generally consists 

of three steps that together lead to conclusions regarding the 

effects of various management options (fig. 6). To assess 

mesohabitats, geospatial measurements (data associated with 

a particular location) are made as a first step to generate maps, 

which provide quantitative descriptions of the ecohydraulic 

habitat conditions in the river over a range of streamflows (that 

is, how the various mesohabitat types change under different 

streamflow conditions) (Bovee and others, 1998, 2008). The 

second and third steps include the collection of physical 

measurements and biological measurements, respectively, 

both of which are used to determine habitat use by selected 

fish species. Changes in habitat conditions with changing 

streamflow magnitude can then be determined by using 

mechanistic hydraulic models or statistical approaches.

Because the size and distribution of habitats can change 

in response to changes in streamflow, it is important to 

evaluate the physical characteristics and fish assemblage at the 

appropriate scale. Mesohabitats are an appropriate scale for 

mapping; although their size and distribution may change, the 

assemblage of mesohabitats is generally constant (Armitage, 

1995), and aquatic organisms have adapted to the physical 

characteristics and temporal dynamics of the mesohabitat with 

which they are associated (Southwood, 1988). 

In this study, mesohabitats were mapped at the 

mesohabitat scale at each site. The following mesohabitats 

were mapped: riffles, runs, pools (channel and eddy), isolated 

pools, forewaters, backwaters, embayments, and flats (table 2; 

fig. 7). Point bars and channel bars (table 2; fig. 7) were also 

mapped to provide a more complete assessment of the active 

channel at each site. Data from two types of pools—channel 
10 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Measured discharge at

sampling sites (table 1)

Daily mean discharge

PNB - Peña Blanca

BRN - Bernalillo

LOR - La Orilla

PAD - Los Padillas

LL1 - Los Lunas I

LL2 - Los Lunas II

ABY - Abeytas

LJY - La Joya

RSL - Rio Salado

LEM - Lemitar

ATJ - Arroyo del Tajo

SPD - San Pedro

BA1 - Bosque del Apache I

BA2 - Bosque del Apache II

laf15-CSSJ00-0678_fig 04

SPD, Dec. 6

BA1, Feb. 8

BA2, Feb. 9

November December January February March April May June July

2011

August

2012

ATJ, June 9

ATJ, Dec. 3

LEM, Dec. 3

LEM, Aug. 7

D

0

1,200

1,400

1,600

1,800

2,000

2,200

800

600

400

200

LL1, June 6

LL2, June 7

LL1, Nov. 14

ABY, Nov. 29

RSL, Dec. 1

LJY, Nov. 30

LJY, Aug. 9

RSL, Aug. 8

ABY, June 8

C

LOR, Nov. 17

PAD, Nov. 16

PAD, Aug. 10

BRN, Nov. 12

B

LOR, Aug. 13

0

1,200

1,400

1,600

1,800

2,000

2,200

800

600

400

200

0

1,200

1,400

1,600

1,800

2,000

2,200

800

600

400

200

A

Daily mean discharge, in cubic feet per second

Date

PNB, Nov. 11

0

1,200

1,400

1,600

1,800

2,000

2,200

800

600

400

200

SPD, June 11

BA2, June 13

BA1, June 12

Figure 4. Measured daily mean discharge at U.S. Geological Survey streamflow-gaging stations A, 08317400 Rio Grande below Cochiti 

Dam, New Mexico; B, 08329918 Rio Grande at Alameda Bridge at Alameda, N. Mex.; C, 08331160 Rio Grande near Bosque Farms, N. 

Mex.; and D, 08355050 Rio Grande at bridge near Escondida, N. Mex.; November 1, 2011–August 31, 2012.
Methods of Investigation 11

70

90

110

130

150

170

190

210

230

River mile

January February March April May June July August September October November December

A. 2011

EXPLANATION

Peña Blanca (0, 0)

Bernalillo (0, 0)

La Orilla (0, 0)

Barelas (0, 0)

Los Padillas (0, 0)

Los Lunas I (0, 19)

Los Lunas II (60, 102)

Abeytas (0, 87)

La Joya (0, 0)

Rio Salado (0, 0)

Lemitar (0, 0)

Arroyo del Tajo (29, 64)

San Pedro (49, 106)

Bosque del Apache I (51, 108)

Bosque del Apache II (58, 115)

Middle Rio Grande Bosque

Initiative Reaches

Cochiti

Angostura

Isleta

San Acacia

River drying status—Dashed when wet and solid when dry; number of dry days in 2011 and 2012

shown in consecutive order in parentheses

Figure 5. Periods of streamflow and river fragmentation in the Middle Rio Grande, New Mexico, January 1, 2011–December 31, 2012.
12 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

laf15-CSSJ00-0678_fig 05B River mile

70

90

110

130

150

170

190

210

230

January February March April May June July August September October November December

B. 2012

EXPLANATION

Peña Blanca (0, 0)

Bernalillo (0, 0)

La Orilla (0, 0)

Barelas (0, 0)

Los Padillas (0, 0)

Los Lunas I (0, 19)

Los Lunas II (60, 102)

Abeytas (0, 87)

La Joya (0, 0)

Rio Salado (0, 0)

Lemitar (0, 0)

Arroyo del Tajo (29, 64)

San Pedro (49, 106)

Bosque del Apache I (51, 108)

Bosque del Apache II (58, 115)

Middle Rio Grande Bosque

Initiative Reaches

Cochiti

Angostura

Isleta

San Acacia

River drying status—Dashed when wet and solid when dry; number of dry days in 2011 and 2012

shown in consecutive order in parentheses

Figure 5. Periods of streamflow and river fragmentation in the Middle Rio Grande, New Mexico, January 1, 2011–December 31, 2012.—

Continued
Methods of Investigation 13

laf15-CSSJ00-0678_fig 06

Mesohabitat

assessment

Run

Point bar

Channel bar

Channel bar

Example river system

Physical measurement Biological measurement

Geospatial measurement

Mapping

Figure 6. Overview of approach used to assess mesohabitats in the Middle Rio Grande, New Mexico (modified from Parasiewicz and 

Dunbar, 2001). 
14 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

and eddy—were combined into a “pools” category for analysis 

because combining the two pool types into a single “pool” 

category resulted in an adequate sample size of “pools” and 

was thought to be more appropriate for the analysis of fish data. 

In this report, forewaters, backwaters, and embayments were 

collectively referred to as “margin pool” mesohabitats because 

the physical characteristics (depth, velocity, and bed substrate) 

of the three mesohabitats were so similar. The mesohabitat types 

used in this report are further described in table 2.

Various software, hardware, and field mapping methods 

were employed to accomplish the project mapping goals. Digital 

mapping techniques were used for all spatial measurements 

collected during this study. Mapping included the use of a 

GIS (Esri, 2013) and a GPS in concert to capture the mapping 

image in the field. The GPS data were captured by using a 

Trimble DSM 232 modular receiving unit (Trimble, 2015a). 

For purposes of this study, a corrected signal from OmniSTAR 

(subscription service) (Trimble, 2015b) was received through 

the Trimble receiving unit to gain the accuracy (subfoot, real 

time) needed for mapping. The GPS data were input directly 

into a laptop computer and visualized onsite by using GIS. 

Field mapping was done by using a variety of approaches 

based on streamflow conditions, river depth, and riverbank 

accessibility. All 15 sites were visited at least once (table 

1), and 13 sites were visited twice during each of the two 

streamflow regimes identified for this study. For the majority 

of the field mapping, project personnel began by walking 

the water’s edge along the 1-km reach at each site in order 

to collect GPS data along the study area extent. This process 

required two individuals, one of which would delineate the 

edge of discrete mesohabitats by using the GPS receiver, 

while the second individual would attribute the incoming GPS 

data in real time. Large, continuous runs, which were often 

500 m or more of the 1-km reach length at a given site, were 

subdivided and mapped as separate runs by using the upstream 

and downstream boundaries of channel features like point bars 

and channel bars to set the mapped upstream and downstream 

boundaries of these mesohabitats. Polygons created through 

this process were stored and attributed in the GIS in association 

with high-resolution remotely sensed imagery, creating a 

detailed map of each study reach at each targeted streamflow. 

Table 2. Description of mesohabitat types (modified from Platania, 1993) and channel features that were mapped on the Middle Rio 

Grande, New Mexico, 2011–12.

[ft/s, feet per second; ft, feet; NA, not applicable]

Mesohabitat 

type Description

Velocity minimum 

to maximum 

(ft/s)

Depth minimum 

to maximum 

(ft)

Riffle Relatively shallow and low to moderate velocity feature characterized by 

moderately turbulent water

-0.05–4.80 0.01–2.58

Run Relatively high-velocity feature with laminar flow and a nonturbulent surface -1.05–5.39 0.02–4.31

Pool Feature with little or no velocity that may be deep in places -2.14–1.70 0.04–4.40

 (a) Channel Type of pool where current moves in the same flow direction as the channel

 (b) Eddy Type of pool where current moves in the opposite direction relative to flow

Isolated pool Type of pool that is separate from the main channel; frequently a portion of a 

former backwater or forewater that has become disconnected from a secondary 

channel

-0.06–0.21 0.01–2.40

Forewater Slackwater feature oriented into the principal direction of flow -0.10–0.08 0.01–1.00

Backwater Slackwater feature oriented in an opposing direction to the principal flow direction -0.23–2.25 0.01–2.87

Embayment Slackwater feature located adjacent to the channel and oriented perpendicular to 

flow

-0.27–1.02 0.03–1.26

Flat Very shallow, low-velocity feature typically located on the periphery of an 

existing point or channel bar; caused by a slight rise in stage

-0.62–3.13 0.01–2.4

Channel 

feature Description

Point bar Crescent-shaped depositional feature located on the inside of a stream bend; 

typically either devoid of or containing annual vegetation

NA NA

Channel bar Transitory parcel of land surrounded by water; typically either devoid of or 

containing annual vegetation

NA NA
Methods of Investigation 15

Riffle

Backwater

Isolated pool

Forewater

Eddy pool

Channel pool

Run

Embayment

Point bar

Channel

bar

Flat

Run

Run

Run

Riffle

Flat

Run

Margin

Pool

Secondary channel trace

PLAN VIEW PROFILE REVIEW

laf15-CSSJ00-0678_fig 07

Figure 7. Mesohabitat types identified in the Middle Rio Grande, New Mexico (modified from Platania, 1993).
16 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Physical Characteristics and Water-Quality 

Properties of Mesohabitats

Physical characteristics were not measured in all of 

the mapped mesohabitats because of time constraints; the 

number of each mesohabitat type sampled was in proportion 

to the abundance of that mesohabitat type. A subset of 

20 mesohabitats at each site was evaluated in winter 2011–12; 

this was increased to 30 mesohabitats during the summer of 

2012 because of the opportunity for increased sampling effort 

afforded by lower river streamflows and extended daylight 

hours. If three or fewer of a given mesohabitat type were 

present in the study reach, then all mesohabitats of that type 

were typically sampled. Mesohabitats selected for collection 

of physical characteristics were distributed throughout the 

entire study reach where possible. 

Once a particular mesohabitat had been selected, 

representative locations for physical characteristic 

measurements were established by delineating five evenly 

spaced transects oriented perpendicularly to the direction of 

streamflow across each mesohabitat (or three evenly spaced 

transects for mesohabitats less than 10 m long, parallel to flow 

direction) and randomly selecting a starting measurement 

location (left center, center, or right center) at the first 

transect (fig. 8A). Physical characteristics were measured at 

1 of 3 different locations (left center, center, or right center) 

along each transect. The measurement location along the 

first transect measured within a mesohabitat was randomly 

selected, and subsequent measurements were made at each 

transect by following a progression from left to right; for 

example, if the first transect measurement was randomly 

selected at the left center location, the subsequent transect 

measurements were consecutively made at center, right 

center, left center, and center.

The following physical characteristic measurements 

were made at the specified location along each transect: 

depth, velocity, dominant substrate type and size, and percent 

embeddedness. Velocity and depth measurements were made 

by wading the stream with a FlowTracker hand-held acoustic 

Doppler velocimeter attached to a wading rod (SonTek, 

2013). Standard USGS protocols for measuring velocity were 

followed (Rantz and others, 1982; Turnipseed and Sauer, 

2010). Velocities were measured by orienting the acoustic 

velocimeter upstream, and in the case of several eddy pools, 

which have currents that move in the opposing direction to the 

main current, negative velocity measurements were common. 

Small negative velocities can also be caused by wind blowing 

upstream over stagnant water, particularly in relatively 

shallow mesohabitats such as isolated pools, forewaters, 

backwaters, and embayments (table 2). In order to convey the 

directional aspect associated with measured velocities and 

thereby describe the magnitude of streamflow within eddy 

pools, the negative sign was retained. In some cases, depths 

and velocities could not be measured at the predetermined 

measurement location because the water was either more 

than 4 feet (ft) deep and thus too deep for a conventional 

wading rod measurement, or the velocity was too great for the 

technician to safely wade the stream. In these circumstances, 

the technician would make the measurement as close as 

possible to the predetermined measurement location (typically 

within a few meters). Dominant substrate was determined 

by the technician while he or she was positioned at a given 

location in the stream transect for the purpose of making 

velocity and depth measurements. Particles were classified by 

referring to the Wentworth scale, which classifies sediment 

particles as cobbles if they are greater than 64 mm and less 

than or equal to 256 mm in length, as gravel if they are greater 

than 2 mm and less than or equal to 64 mm in length, as sand if 

they are greater than 0.0625 mm and less than or equal to 2 mm 

in length, and fines (silt and clay) if they are less than or equal 

to 0.0625 mm in length (Wentworth, 1922). Embeddedness 

was determined by measuring (particles greater than or equal to 

2 mm) or estimating (particles less than 2 mm) the percentage 

(to the nearest 10 percent) of the surface area of the particle 

that was covered in sand or finer bed material (Fitzpatrick and 

others, 1998).

Physical characteristic measurements along the stream 

margins were only measured at the center transect of each 

mesohabitat selected for physical assessment. In this study, 

a margin was defined as the relatively shallow area (fig. 7) 

adjacent to the edge of the water, which is characterized 

by low velocities compared to more central sections of the 

stream channel. Stream-margin width was defined by the 

first noticeable change in bed slope starting from the bank 

toward the center of the stream or when a depth of 1 ft was 

reached, whichever was first. If the bank was vertical, then 

a default margin width of 1 ft was assigned. Shallow, lowvelocity, nearshore areas are often associated with large algal 

productivity (Bixby and Burdett, 2009), and Rio Grande silvery 

minnow is often associated with these productive areas of a 

stream (Dudley and Platania, 1997). Measurements of margin 

physical characteristics were made on both the left and right 

bank (facing downstream) but were not made if the edge of 

the mesohabitat at the measuring point was embedded in the 

stream channel and not adjacent to a bank, island, channel 

bar, or point bar. The following margin-specific data were 

collected at each margin within a 0.25-square meter (m2

)

quadrat centered at the midpoint of margin width: width, 

depth (collected at midpoint of margin), two-dimensional 

velocity (collected at midpoint of margin), dominant substrate 

type and size, subdominant substrate type and size, percent 

embeddedness, percent periphyton cover, bank angle, and 

canopy cover (based on densiometer readings). Periphyton 

cover was estimated as the percent (to the nearest 10 percent) 

of the area within the 0.25-m2

 quadrat that was covered by 

algae or vascular plants. Bank angle was defined in this study 

as the angle of the above-water shoreline associated with the 

channel feature (island, channel bar, point bar) that bounded 

the mesohabitat, and as many as three angle measurements (to 

the nearest degree) were collected (by using a clinometer) from 

the edge of water to the first break in slope on the shoreline 

and used to calculate a mean bank angle. If the bank was a cut 
Methods of Investigation 17

 

Flow direction

EXPLANATION

Sampling locations for 

Physical characteristics

Water-quality properties (at low-flow regime only)

Upstream starting locations of seine hauls

Left center

Center

Right center

Left center

Center

Top

left

Top

middle

Top

right

Middle

left

Middle

middle

Middle

right

Bottom

left

Bottom

middle Bottom

right

Transect 1

Transect 2

Transect 3

Transect 4

Transect 5

A B

NOTE: Orientation of sampling locations for physical characteristics assumes

a hypothetical starting point on transect 1 of “left.” 

laf15-CSSJ00-0678_fig 08

Figure 8. Sampling patterns in mesohabitats. A, Sampling pattern for collection of physical characteristics and water-quality 

properties. B, Sampling patterns for seine hauls.
18 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

bank (bank angle greater than 70 degrees at the edge of water), 

then a margin width of 0.25 m was assigned because the cut 

bank was in effect the first break in slope off of the bank. The 

margin-specific data are included in the project geospatial 

database but were not analyzed as part of this investigation.

Selected water-quality properties were measured by using 

a YSI 600XL multiparameter sonde (Xylem, Inc., 2013) by 

following procedures outlined in the USGS National Field 

Methods Manual (U.S. Geological Survey, variously dated). 

Each probe (other than temperature, which is not calibrated but 

rather is checked semiannually) was calibrated in the field daily 

prior to the collection of field measurements. The following 

data were recorded: temperature (in degrees Celsius [°C]), 

specific conductance (in microsiemens per centimeter [μs/cm] 

at 25 °C), dissolved oxygen (in milligrams per liter [mg/L]), 

and pH (in standard units). 

Water-quality data were collected at one location (at the 

midpoint of the middle transect) within a given mesohabitat 

by the crew of technicians collecting mesohabitat data and 

at a second location within a given mesohabitat by the 

crew of technicians collecting fish. The sonde was placed 

approximately 1 ft below the water surface at these locations 

during data collection, depth permitting; otherwise, the sonde 

was placed at the midpoint of the water column. Water-quality 

data were collected only during the morning to early afternoon 

and did not capture the thermal maxima (late afternoon) and 

dissolved oxygen minima (early morning). Water-quality 

properties were only collected during summer 2012, when 

low-streamflow conditions existed and water-quality properties 

were thought to be potentially most limiting to aquatic life. 

Water temperatures in the Middle Rio Grande are typically 

higher, and dissolved oxygen concentrations are typically 

lower during relatively low-streamflow conditions compared 

to relatively high-streamflow conditions. Water temperature 

inversely controls the solubility of oxygen in water; as 

temperature increases, oxygen is less soluble. Dissolved 

oxygen concentrations in streams are therefore typically lower 

during the warmer summer months compared to the rest of the 

year. Measurement of water temperature and dissolved oxygen 

was not done to verify thresholds for dissolved oxygen (less 

than 3.3 mg/L; Matthews and Maness, 1979) and temperature 

(more than 30 °C; U.S. Fish and Wildlife Service, 2003) 

that have been established for Rio Grande silvery minnow 

but rather as additional field data to augment the primary 

mesohabitat data that are the focus of this report. 

Fish Assemblage Surveys of Mesohabitats

Fish assemblage surveys were done to assess species 

composition at all 15 sites during winter 2011–12 and at 13 

of the 15 sites during summer 2012 (table 1). The two most 

upstream sites, Peña Blanca and Bernalillo, were not sampled 

during summer 2012 because streamflows were much higher at 

these sites when they were scheduled for sampling compared to 

streamflows at the more downstream sites (fig. 4). In addition, 

streamflows at Peña Blanca and Bernalillo during summer 

2012 were not representative of a summer low-streamflow 

regime that was targeted for sampling. Staff with the U.S. 

Fish and Wildlife Service New Mexico Fish and Wildlife 

Conservation Office in Albuquerque, N. Mex., conducted all 

fish assemblage surveys, maintained required Federal permits 

to collect and handle Rio Grande silvery minnow, and were 

responsible for onsite fish identifications and counts.

Twenty mesohabitats were subsampled at each site during 

winter 2011–12, and 30 mesohabitats were subsampled during 

summer 2012. Twenty was initially selected as the number 

of mesohabitats to sample because that was thought to be the 

number of mesohabitats that could be sampled in the 1 day 

per site that was available for sampling. Catch per unit effort 

(CPUE), which was lower than expected during winter 2011–

12, was expected to improve in summer 2012. Compared to 

winter, summer is when fish are generally more active because 

of warmer water temperatures, and thus more likely to be 

caught. Fish also are more abundant in summer compared to 

winter as a result of spring and summer recruitment, and more 

mesohabitats at each site are accessible during the summer 

compared to winter. Despite the expected improvement in 

CPUE in summer 2012 relative to winter 2011–12, the number 

of mesohabitats sampled in summer 2012 was increased to 

30 mesohabitats to increase sampling effort. The number of 

each mesohabitat type sampled was in approximate proportion 

to the abundance of that mesohabitat type. If three or fewer of 

a given mesohabitat type were present in a given study reach, 

all mesohabitats of that type were typically sampled.

Fish were collected by using a seine while wading during 

both winter and summer sampling. A seine is a net suspended 

vertically in the water by floats at the top and weights at the 

bottom. Catching fish with seines is referred to as “seining,” 

and a single sampling effort, or “drag,” of a seine in this study 

is referred to as a “seine haul.” A flat-panel seine, 3.0 m in 

length and 1.5 m in height, with a mesh size of 3.0 mm was 

used. The sampling approach was the same as the sampling 

approach described in Moring and others (2014) and was 

deliberately biased toward collecting fish from shallow, lowvelocity, nearshore habitats preferred by Rio Grande silvery 

minnow and similar fish; for example, 3.0-mm mesh seines 

were used, as opposed to a larger mesh size, to increase the 

likelihood of collecting Rio Grande silvery minnow and 

other minnow species. During each seine haul, two biologists 

dragged the seine through the water in an upstream to 

downstream direction for a distance of at least 1 m and as 

much as approximately 25 m depending on the size of the 

mesohabitat being sampled; the distance that the seine was 

dragged is referred to as the “seine-haul length.” Seining was 

done in a downstream direction in each mesohabitat, with the 

exception of riffles where a kick-seining technique was used. 

Kick-seining involved the seine being held in a fixed position 

at the downstream end of the seine-haul location, while 1 or 

2 people disturbed the substrate with their feet as they moved 

downstream toward the seine; the seine was lifted from the 

water when the 1 or 2 people reached the seine. 
Methods of Investigation 19

At least two seine-haul locations were selected in each 

mesohabitat sampled except in small mesohabitats (less than 

5 m long), which were only seined once. Each seine-haul 

location was randomly selected from nine available sampling 

points in each mesohabitat corresponding to a near left bank 

(left), near center channel (middle), and near right bank (right) 

points along each of three transects. Sampling transects in each 

mesohabitat were distributed at intervals equal to one-quarter, 

one-half, and three-quarters the length of each mesohabitat 

to ensure that all seine-haul locations were embedded within 

the sampled mesohabitat (fig. 8B). All fish collected in each 

haul were identified, counted, and released. There was little 

concern for recollecting the same fish from a previous seine 

haul because of the distance between each seine haul (typically 

at least 10–20 m) and because all seine hauls were made 

from upstream to downstream. Fish data were recorded in the 

field by using waterproof data sheets during winter 2011–12 

and tablet computers in summer 2012; all of the data were 

reviewed by staff at the USGS Texas Water Science Center 

for completeness and accuracy. The reviewed data were 

entered into an electronic spreadsheet and incorporated into a 

geospatial database.

Comparisons of fish assemblage data within and among 

the sites that were assessed during the study were made by 

analyzing total abundance data, fish-species richness, relative 

abundance, total fish density, and CPUE. Total abundance 

refers to the number of individuals of each species that were 

collected. Fish-species richness refers to the total number 

of fish species collected and is a commonly used metric for 

comparing fish assemblages among sites and streamflow 

regimes (Ludwig and Reynolds, 1988). For this report, 

relative abundance refers to the proportion of individuals of a 

given species that were collected relative to the total number 

of individuals of all species that were collected; relative 

abundance is reported as a percentage. The dimensions of each 

seine haul were recorded to enable the calculation of CPUE 

per seine haul, which reports the number of fish per unit area, 

thereby allowing for comparisons between sites regardless of 

the number of seine hauls completed at each site. The CPUE 

was calculated by dividing the total number of fish caught by 

either the total area seined or by the area kicked from a kickseine haul; the resulting quotient was then multiplied by 100 m2

to obtain the CPUE. The use of CPUE to standardize fish 

data allows for direct comparisons between stream reaches or 

mesohabitats of different sizes; the use of CPUE is a common 

practice among aquatic biologists (Nielsen and Johnson, 1983).

Canonical correspondence analysis was used to 

evaluate the relation of fish-species composition to selected 

environmental variables (physical characteristic data collected 

at the mesohabitat scale [depth, velocity, and substrate 

particle size] and mesohabitat types); that is, CCA was used 

to determine how correlated fish-species composition was to 

each of the mesohabitat types and to channel depth, velocity, 

and substrate particle size. Canonical correspondence analysis 

is a multivariate analysis technique developed to relate 

species composition to “known variation” in the environment 

(ter Braak, 1986; p. 1167). The input for CCA was a table 

containing the total abundance of each fish species, the means 

of depth and velocity, and predominant substrate particle size 

in each mesohabitat sampled during both sampling periods. 

Depth, velocity, and substrate particle size were measured 

from 3 to 5 times (depending on the length of the mesohabitat) 

within each randomly selected mesohabitat. Ecologists use 

CCA to relate the abundance of multiple species to one or 

more environmental variables thought to influence their 

abundance (ter Braak, 1986). The CCA diagram consists of 

four quadrants, and the x (CCA Axis 1) and y (CCA Axis 2) 

axes (referred to as “ordination axes”) are dimensionless, linear 

combinations of the explanatory or environmental variables 

(Guisan and Zimmermann, 2000). The CCA extracts synthetic 

environmental gradients from datasets, and the gradients 

are the basis for describing and visualizing different habitat 

preferences (depth, velocity, and substrate) of species in an 

ordination diagram (ter Braak and Verdonschot, 1995) that 

maximizes the niche separation among the species along the 

ordination axes. As an eigenvalue-ordination procedure, the 

first eigenvalue calculated by CCA is equal to the maximum 

dispersion of species scores along the first CCA axis (ter Braak, 

1987), and therefore the first CCA axis explains the majority 

of the variation in species and environmental variables. The 

eigenvalue associated with the second CCA axis is equal to 

the next largest dispersion of species scores, and this axis 

explains the next largest variation in species and environmental 

variables. Theoretically, there can be as many ordination axes 

in CCA as there are environmental variables, and each axis 

explains less variation and is uncorrelated to the axis or axes 

extracted previously (ter Braak and Verdonschot, 1995).

Geospatial Database1

Data collected during the study were processed in two 

ways. First, a geospatial database was developed for the 

management of field-collected data. This format allows 

end-users to query, manipulate, and export the geographic 

and tabular data by using a GIS to create maps and perform 

spatial analyses by using the geographic features and their 

related tabular information. Second, the data presented in 

the geospatial database were organized for inclusion with 

this report. 

A geospatial database is a spatially enabled database 

that contains spatial and tabular data and allows users to 

associate tabular data with physical and spatial components 

(Zeiler, 1999; Shah and Houston, 2007). A geospatial database 

is capable of handling data efficiently through the use of a 

relational database management system. By using GIS, the 

spatial data can be viewed in combination with other relevant 

geospatial data layers, including aerial imagery, to analyze 

distribution patterns, data gaps, and spatial relations and to 

create cartographic representations of the geospatial database 

contents. A geospatial database contains several database 

1

This section was modified from Moring and others (2014).
20 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

objects: feature classes, relationship classes, and attribute 

tables. Feature classes store geospatial data objects of similar 

geometry type (point, line, or polygon). A collection of feature 

classes is stored and managed in a feature dataset, which uses 

a single, defined geographic or projected coordinate system 

for all data stored within the database object. Relationship 

classes link geospatial data stored in the feature classes 

with related tabular information stored in attribute tables. 

Relationship classes allow the end-user to query data by 

establishing connections between geospatial data stored in the 

feature classes and related tabular information stored within 

the geospatial database attribute tables (Zeiler, 1999). The 

geospatial database design was based on an Esri ArcGIS 10.0 

personal geospatial database platform (Esri, 2013). ArcGIS 

personal geospatial databases store database information as 

Microsoft Access (1997–2003) files.

The project geospatial database contains a collection of 

all the geographic and tabular data collected in the field in 

addition to the associated metadata (fig. 9). The geographic 

data presented in the geodatabase include the mapped 

mesohabitat polygons for each of the winter 2011–12 data 

collection efforts, as well as the summer 2012 data collection 

efforts. The polygon feature classes (mesohab_11092011, 

mesohab_02052012, and mesohab_06052012) contain 

information related to the areal extent of each unit, as well as 

descriptions of each mesohabitat class and the length of the 

mapped feature. The related tabular information, derived from 

the collection of physical characteristic data and fish sampling 

in the field, was parsed out into seven different related tables. 

Each record in the data tables is related to a corresponding 

geographic feature through the use of a primary key. The 

primary key is a unique identifier (unique_id) that is utilized 

by the relationship classes to link the geographic and tabular 

data (Zeiler, 1999) (fig. 9). Data tables and definitions of data 

elements associated with the project geospatial database are 

described in appendix 3, and the Federal Geographic Data 

Committee compliant metadata record for the project database 

is shown in appendix 4.

Physical Characteristics and WaterQuality Properties of Mesohabitats 

over a Range of Streamflows

The physical characteristics of measured depth and 

velocity (fig. 10) varied greatly by mesohabitat type, site, and 

sampling period (winter 2011–12 or summer 2012). Measured 

depths ranged from 0.01 ft in six mesohabitats at five different 

locations to 4.4 ft in a pool at the Bosque del Apache II site 

on June 13, 2012. In some cases, the stage (water-surface 

elevation of the stream above an arbitrary datum) (Langbein 

and Isseri, 1960; Rantz and others, 1982) may have changed 

slightly between the time that a site was mapped and the time 

that physical characteristics were measured (typically a day 

later; table 1). The lowest velocity (-2.14 feet per second 

[ft/s]) was measured in a pool at the Peña Blanca site on 

November 11, 2011; whereas, the highest velocity (5.39 ft/s) 

was measured in a run at the Lemitar site on December 2, 

2011 (fig. 10). Physical characteristics of measured depth and 

velocity for the San Pedro site are not shown on figure 10 

for December 6, 2011, because no associated fish data were 

collected on that date; therefore, physical characteristic data 

from February 7, 2012, are shown.

To represent the relative contributions to mean waterquality properties of the different mesohabitats, area weighting 

was applied to the mesohabitat areas delineated at each 

site. Area-weighted values by site were made by summing 

the products of the areal extent of each mesohabitat where 

water-quality properties were measured by the value for the 

water-quality property associated with that same mesohabitat 

for all mesohabitats where water-quality properties were 

measured; the resulting sum was then divided by the sum 

of the areal extents for all mesohabitats where water-quality 

properties were measured. Areal extents for all mesohabitats 

can be found in the geospatial database in the following tables: 

mesohab_11092011 (sites mapped during November and 

December 2011), mesohab_02052012 (sites mapped during 

February 2012), and mesohab_06052012 (sites mapped during 

June and August 2012). Area weighting ensured that mean 

values reported for each site would be proportional to the areal 

extent of the mesohabitats. All references to mean depths, 

velocities, and water-quality properties in this report refer to 

area-weighted mean values calculated for each site; substrate 

composition was also area weighted. 

After applying area weighting to the depth and velocity, 

the sites that were sampled in winter 2011–12 and summer 

2012 tended to have smaller mean depths and mean velocities 

during summer 2012, when streamflows tended to be lower 

compared to winter 2011–12 (fig. 11). There were three 

instances in which mean depths or mean velocities were 

higher in summer 2012 at a site than they were in winter 

2011–12: the Barelas site had a slightly lower mean depth in 

winter 2011–12 (1.33 ft) relative to summer 2012 (1.45 ft), 

and the Abeytas site had both a lower mean depth (1.03 ft) 

and mean velocity (0.95 ft/s) in winter 2011–12 relative to 

summer 2012 (1.22 ft and 1.22 ft/s, respectively). Larger mean 

depths or velocities at these three sites during summer 2012 

were likely caused, at least in part, by the fact that physical 

characteristics were not measured in the same mesohabitats 

during both sampling periods. It was not possible to map 

the same mesohabitats with each sampling period at any of 

the sites because the extent and type of each mesohabitat 

changed from winter 2011–12 to summer 2012. Most of the 
Moderate streamflow Low streamflow 

(tbl_fish)

(tbl_fishcover)

(tbl_fish_habitat)

(tbl_physical)

(tbl_margin)

(tbl_water_quality)

(tbl_mesohab_all)

(mesohab_11092011)

(mesohab_02052012)(mesohab_06052012)

(tbl_discharge)

Moderate streamflow

[November/December 2011]

[February 2012]

[June/August 2012]

Geodatabase Data Model

Project geodatabase 

Fish assemblage

EXPLAN

Feature class—stored as polygfeature-class ashown in paren

Attribute table—in rows and colufeature class; atshown in parent

Geodatabase

Relationship clinformation and 

Data-model elem

Fish cover

Fish habitat 

Physical characteristics

Margin

Water quality

Site information

Streamflow data

laf15-CSSJ00-0678_fig 09

Figure 9. Simplified geospatial database data model for the spatial and tabular mesohabitat data collected from 15 U.S. Geological Survey siteGrande, New Mexico, winter 2011–12 and summer 2012. 
22 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10A

*

Depth, in feet, and velocity, in feet per second

-1

0

1

2

3

4

5

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

Cochiti reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

Peña Blanca, November 11, 2011

Discharge: 552 cubic feet per second (ft3

/s)

( -2.14) *

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012. 

sites included one or more deep, wide, high-velocity runs 

that greatly contributed to mean depths and velocities. These 

deep, wide, high-velocity runs were typically adjacent to one 

another and behaved as a single continuous run. The ratio 

of the areal extent of deep, wide, high-velocity runs where 

physical habitat features were measured (on the basis of the 

random selection process described previously) relative to 

the total areal extent that these runs occupied varied a great 

deal from site to site, which likely had a large effect on the 

mean depths and velocities that were calculated for each site. 

Because instantaneous discharge was not measured at the 

San Pedro site on February 7, 2012, physical characteristics 

measured at the San Pedro site on December 6, 2011, were 

used in figure 11.

The streamflows at each site were determined one of 

two ways. Instantaneous discharge measurements were made 

at most sites in accordance with standard USGS discharge 

measurement methods (Rantz and others, 1982; Turnipseed 

and Sauer, 2010). At the following sites (Barelas on 

November 10, 2011, and August 11, 2012; Los Lunas II on 

November 15, 2011), the mean daily discharge was obtained 

from the USGS National Water Information System (NWIS) 

for the nearest upstream USGS streamflow-gaging station 

(table 1). Instantaneous discharge measurements were stored in 

NWIS (U.S. Geological Survey, 2014). Although the amount 

of discharge measured was at times highly variable between 

sites during winter 2011–12, discharge tended to increase in 

the downstream direction at the 6 most upstream sites, whereas 

discharge tended to decrease in the downstream direction at the 

9 remaining sites (fig. 11E). This overall pattern might be an 

artifact of water-management decisions as the six upstream sites 

had likely not yet reached equilibrium during the nonirrigation 

season; that is, residual irrigation return flows were likely 

still contributing to streamflow at the six most upstream sites. 

During winter 2011–12, discharge measurements at sites ranged 

from 552 ft3/s at the Peña Blanca site on November 11, 2011, to 

991 ft3/s at the La Joya site on November 30, 2011 (a November 

15, 2011 discharge of 1,050 ft3/s is listed in table 1 for the Los 

Lunas II site, but this higher value is from USGS streamflowgaging station 08331160 (fig. 2) approximately 10 miles 

upstream from the Los Lunas II site). During summer 2012, 

discharge ranged from 4.13 ft3/s at the Lemitar site on August 7, 

2012, to 430 ft3

/s at the La Orilla site on August 13, 2012 (table 

1). 
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 23

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Los Padillas, November 16, 2011

Discharge: 851 ft3

/s

Depth, in feet, and velocity, in feet per second

Barelas, November 10, 2011

Discharge: 850 ft3

/s

Depth, in feet, and velocity, in feet per second

La Orilla, November 17, 2011

Discharge: 746 ft3

/s

Depth, in feet, and velocity, in feet per second

Bernalillo, November 12, 2011

Discharge: 570 cubic feet

per second (ft3

/s)

Depth, in feet, and velocity, in feet per second

Angostura reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

-1

0

1

2

3

4

5

-30

0

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10B

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
24 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Los Padillas, August 10, 2012

Discharge: 334 ft3

/s

Depth, in feet, and velocity, in feet per second

Barelas, August 11, 2012

Discharge: 351 ft3

/s

Depth, in feet, and velocity, in feet per second

La Orilla, August 13, 2012

Discharge: 430 cubic feet

per second (ft3

/s)

Depth, in feet, and velocity, in feet per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

Angostura reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10B_2

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 25

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

Isleta reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

-1

0

1

2

3

4

5

-30

0

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

La Joya, November 30, 2011

Discharge: 991 ft3

/s

Abeytas, November 29, 2011

Discharge: 940 ft3

/s

Los Lunas II, November 15, 2011

Discharge: 1,050 ft3

/s

Los Lunas I, November 14, 2011

Discharge: 749 cubic feet

per second (ft3

/s)

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10C Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
26 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

Isleta reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

-1

0

1

2

3

4

5

-30

0

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

Rio Salado, December 1, 2011

Discharge: 970 cubic feet

per second (ft3

/s)

Abeytas, June 8, 2012

Discharge: 179 ft3

/s

Los Lunas II, June 7, 2012

Discharge: 243 ft3

/s

Los Lunas I, June 6, 2012

Discharge: 258 ft3

/s

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10C_2 Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 27

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

Isleta reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

-1

-1

0

1

2

3

4

5

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Rio Salado, August 8, 2012

Discharge: 37.9 ft3

/s

La Joya, August 9, 2012

Discharge: 49.5 cubic feet

per second (ft3

/s)

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10C_3

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
28 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

San Acacia reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

-1

0

1

2

3

4

5

-30

0

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

Bosque del Apache I, February 8, 2012

Discharge: 633 ft3

/s

San Pedro, February 7, 2012

Discharge: not recorded

Arroyo del Tajo, December 3, 2011

Discharge: 870 ft3

/s

Lemitar, December 2, 2011

Discharge: 921cubic feet

per second (ft3

/s)

( 5.39)

( -1.05)

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10D

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 29

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

San Acacia reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

0

1

2

3

4

5

-1

-1

-1

0

1

2

3

4

5

-1

0

1

2

3

4

5

-30

0

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

Bosque del Apache II, February 9, 2012

Discharge: 588 cubic feet

per second (ft3

/s)

San Pedro, June 11, 2012

Discharge: 69.3 ft3

/s

Arroyo del Tajo, June 9, 2012

Discharge: 140 ft3

/s

Lemitar, August 7, 2012

Discharge: 4.13 ft3

/s

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10D_2

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
30 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Depth

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Velocity

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Maximum habitat suitability criteria

(U.S. Fish and Wildlife Service, 2010)

for depth (50 centimeters)

for velocity (40 centimeters per second)

*

Depth, in feet, and velocity, in feet per second Depth, in feet, and velocity, in feet per second

San Acacia reach, Middle Rio Grande Bosque Initiative reach (see fig. 2)

0

1

2

3

4

5

-1

-1

0

1

2

3

4

5

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Depth, in centimeters, and velocity,

 in centimeters per second

-30

0

30

60

90

120

150

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

Bosque del Apache II, June 13, 2012

Discharge: 45.7 ft3

/s

Bosque del Apache I, June 12, 2012

Discharge: 48 cubic feet

per second (ft3

/s)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 10D_3

Figure 10. Depth and velocity in different mesohabitat types at 15 sites on the Middle Rio Grande, New Mexico, winter 2011–12 and 

summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 31

Streambed sediments at the Peña Blanca and Bernalillo 

sites were predominantly coarse gravels and cobble (fig. 

12). Downstream from these two sites, the Rio Grande is 

characterized by a broader, lower gradient channel dominated 

by smaller grained bed materials, primarily sand with some 

silt and clay. Streambed sediments with large amounts of silt 

and clay were prevalent at the midreach sites (Los Lunas I and 

II, Abeytas, La Joya, and Rio Salado). The increase in silts and 

clays at these sites compared to the Peña Blanca and Bernalillo 

sites could be the result of finer grained contributions from 

two large tributaries to the Rio Grande, the Rio Puerco and 

Rio Salado, both of which join the Rio Grande downstream 

from Albuquerque (fig. 2).

Mean values were also computed for the waterquality properties (temperature, dissolved oxygen, specific 

conductance, and pH) measured at each site during summer 

2012. Mean temperatures ranged from 21.47 °C at the San 

Pedro site to 29.03 °C at the Lemitar site. In contrast to 

the mean temperatures calculated for each site, the lowest 

temperature measured in any given mesohabitat was 16.16 °C 

in an isolated pool at the Arroyo del Tajo site, and the 

highest temperature measured in any given mesohabitat was 

36.96 °C in an isolated pool at the Lemitar site (listed in the 

geospatial database attribute table tbl_water_quality). As a 

primary constituent element of critical habitat, the U.S. Fish 

and Wildlife Service (2003, p. 8117) has established that 

“water of sufficient quality to maintain natural, daily, and 

seasonally variable water temperatures in the range of greater 

than 1 °C and less than 30 °C” is needed to provide for the 

“physiological, behavioral, and ecological requirements of 

the [Rio Grande] silvery minnow.” The largest ranges in 

temperature were typically measured in isolated pools, but 

other low-velocity mesohabitats, such as backwaters and 

embayments, also tended to have large temperature ranges 

(fig. 13). Mean site temperatures tended to be higher at the 

sites that were sampled in August (25.57 °C) compared to 

June (24.61 °C) (table 3). The highest mean temperature 

(29.03 °C) was measured at the Lemitar site on August 

7, 2012, coincident with the lowest measured discharge 

(4.13 ft3

/s) in summer 2012 (table 3). Temperature was 

affected by the time of day when it was measured; temperature 

measurements made early in the day tended to be lower than 

those made in the afternoon. Temperature variation also tended 

to be largest in mesohabitats with low velocities because they 

had little to no streamflow, and these mesohabitats also tended 

to be shallower, which reduced their capacity to moderate heat 

through mixing or thermal advection.

Dissolved oxygen concentrations ranged from 1.16 mg/L 

in a backwater at the Lemitar site to 14.52 mg/L in an isolated 

pool at Los Lunas II (fig. 13). Matthews and Maness (1979) 

determined that a dissolved oxygen concentration higher than 

3.3 mg/L (fig. 13) is preferred by cyprinids, but dissolved 

oxygen concentrations as low as 1.5 mg/L may be tolerable. 

The largest ranges in dissolved oxygen concentrations tended 

to be measured in mesohabitats associated with low velocities, 

particularly isolated pools, backwaters, embayments, and, to 

a lesser extent, forewaters. The four most downstream sites 

in downstream order—Arroyo del Tajo, San Pedro, Bosque 

del Apache I, and Bosque del Apache II—tended to have 

narrow ranges in dissolved oxygen concentrations across all 

mesohabitat types (aside from isolated pools at Bosque del 

Apache I) relative to the more upstream sites (fig. 13). Mean 

dissolved oxygen concentrations tended to be lower in August 

(7.46 mg/L) compared to June (8.33 mg/L) (table 3). The 

highest mean dissolved oxygen concentration (9.13 mg/L) 

was measured at the Lemitar site on August 7, 2012, and the 

lowest mean dissolved oxygen concentration (6.23 mg/L) was 

measured at the Los Padillas site on August 10, 2012 (table 

3). The three sites in and near Albuquerque, La Orilla (7.19 

mg/L), Barelas (6.79 mg/L), and Los Padillas (6.23 mg/L), in 

addition to the next downstream site, Los Lunas I (6.91 mg/L), 

tended to have lower mean dissolved oxygen concentrations 

than the remaining sites other than Rio Salado, which had a 

mean dissolved oxygen concentration of 7.07 mg/L (table 3). 

Appreciable diel fluctuations in dissolved oxygen 

concentrations (larger from midafternoon to late afternoon 

and decreasing through the night) are likely in shallow, lowvelocity mesohabitats (isolated pools, forewaters, backwaters, 

and embayments), where large amounts of periphytic algae 

were observed (Huggins and Anderson, 2005). Higher 

dissolved oxygen concentrations were measured in shallow, 

low-velocity mesohabitats (fig. 13) compared to higher 

velocity mesohabitats (riffles, runs, and flats), despite higher 

water temperatures in the low-velocity mesohabitats, most 

likely as a result of the relative abundance of periphyton 

in the low-velocity mesohabitats compared to the higher 

velocity mesohabitats. The dominance of sand (fig. 12) 

in most mesohabitats and a shifting streambed that was 

characteristic in riffles, runs, and flats may account for the 

lack of periphyton in these higher velocity mesohabitats, and 

consequently, the smaller dissolved oxygen concentrations 

measured. Also, dissolved oxygen and the other mesohabitat 

measurements were measured between 9 a.m. and 4 p.m. each 

day, when dissolved oxygen concentrations would be at or 

near their peak daily value.

Specific conductance ranged from 175 μs/cm at 25 °C 

in an isolated pool at the La Orilla site to 2,246 μs/cm at 

25 °C in an isolated pool at the La Joya site (fig. 13). The 

broadest ranges in specific conductance within a mesohabitat 

type were typically measured in isolated pools, particularly 

at the Los Lunas I, La Joya, and Lemitar sites, where specific 

conductance values were the highest. Elevated specific 

conductance in isolated pools may be caused by either the 

evaporative concentration of solutes (Stephens and others, 

1996) or by the mixing of less saline surface water with more 

saline groundwater from the hyporheic zone. Additional 

mesohabitats where low velocities and relatively large ranges 

in specific conductance were measured were backwaters (at 

the La Joya site) and embayments (at the Los Lunas I and 

Abeytas sites). 
32 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

0

200

400

600

800

1,000

1,200

PNB

11/11

BRN

11/12

LOR

11/17

BAR*

11/10

PAD

11/16

LL1

11/14

LL2*

11/15

ABY

11/29

LJY

11/30

RSL

12/1

LEM

12/3

ATJ

12/3

SPD

12/6

BA1

2/8

BA2

2/9

Measured discharge, in cubic feet per second

Sites, listed in order from upstream to downstream

Winter 2011–12

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Winter 2011–12

Area-weighted velocity, in feet per second

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Area-weighted depth, in feet

A Winter 2011–12

C

E

Sampling sites and map identifiers followed by site short names (table 1)

EXPLANATION

PNB - Peña Blanca

BRN - Bernalillo

LOR - La Orilla

BAR - Barelas

PAD - Los Padillas

LL1 - Los Lunas I

LL2 - Los Lunas II

ABY - Abeytas

LJY - La Joya

RSL - Rio Salado

LEM - Lemitar

ATJ - Arroyo del Tajo

SPD - San Pedro

BA1 - Bosque del Apache I

BA2 - Bosque del Apache II

Middle Rio Grande Bosque Initiative reach names (table 1) 

Cochiti reach

Angostura reach

Isleta reach

San Acacia reach

*Discharge was not measured in the field at these locations on the dates shown;

plotted discharge in these cases is the mean daily discharge for the date shown

at the nearest streamflow-gaging station upstream from the site

Figure 11. Area-weighted depths by mesohabitat in A, winter 2011–12 and B, summer 2012; area-weighted velocities by mesohabitat in 

C, winter 2011–12 and D, summer 2012; and measured discharge in E, winter 2011–12 and F, summer 2012. 
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 33

Sampling sites and map identifiers followed by site short names (table 1)

EXPLANATION

PNB - Peña Blanca

BRN - Bernalillo

LOR - La Orilla

BAR - Barelas

PAD - Los Padillas

LL1 - Los Lunas I

LL2 - Los Lunas II

ABY - Abeytas

LJY - La Joya

RSL - Rio Salado

LEM - Lemitar

ATJ - Arroyo del Tajo

SPD - San Pedro

BA1 - Bosque del Apache I

BA2 - Bosque del Apache II

Middle Rio Grande Bosque Initiative reach names (table 1) 

Cochiti reach

Angostura reach

Isleta reach

San Acacia reach

*Discharge was not measured in the field at these locations on the dates shown;

plotted discharge in these cases is the mean daily discharge for the date shown

at the nearest streamflow-gaging station upstream from the site

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SUMMER 2012

PNB BRN LOR

8/13

BAR*

8/11

PAD

8/10

LL1

6/6

LL2

6/7

ABY

6/8

LJY

8/9

RSL

8/8

LEM

8/7

ATJ

6/9

SPD

6/11

BA1

6/12

BA2

6/13

Sites, listed in order from upstream to downstream

SUMMER 2012

Measured discharge, in cubic feet per second

0

50

100

150

200

250

300

350

400

450

500

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

SUMMER 2012

Area-weighted velocity, in feet per second Area-weighted depth, in feet

B

D

F

laf15-CSSJ00-0678_fig 11B

Figure 11. Area-weighted depths by mesohabitat in A, winter 2011–12 and B, summer 2012; area-weighted velocities by mesohabitat in 

C, winter 2011–12 and D, summer 2012; and measured discharge in E, winter 2011–12 and F, summer 2012.—Continued 
34 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

BA2BA1

Area-weighted substrate composition, in percent

EXPLANATION

A. Winter 2011–12 

B. Summer 2012 

hardpan

small boulder (greater than 256) 

cobble (greater than 64 and less than or equal to 256) 

coarse gravel (greater than 16 and less than or equal to 64) 

fine gravel (greater than 2 and less than or equal to 16) 

sand (greater than 0.0625 and less than or equal to 2) 

silt and clay (less than or equal to 0.0625) 

Sample sites and map identifiers followed

by station short names (table 1)

Sediment categories (size in millimeters)—

 Modified from Wentworth (1922) and Guy (1969)

100

90

80

70

60

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

10

0

BARLORBRNPNB PAD LEMRSLLJYABYLL2LL1 ATJ SPD

PNB - Peña Blanca

BRN - Bernalillo

LOR - La Orilla

BAR - Barelas

PAD - Los Padillas

LL1 - Los Lunas I

LL2 - Los Lunas II

ABY - Abeytas

LJY - La Joya

RSL - Rio Salado

LEM - Lemitar

ATJ - Arroyo del Tajo

SPD - San Pedro

BA1 - Bosque del Apache I

BA2 - Bosque del Apache II

Figure 12. Area-weighted substrate composition in A, winter 2011–12 and B, summer 2012.
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 35

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13A

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

La Orilla, August 13, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.
36 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13B

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Barelas, August 11, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 37

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13C

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Los Padillas, August 10, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
38 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13D

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Los Lunas I, June 6, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 39

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13E

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Los Lunas II, June 7, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
40 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13F

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Abeytas, June 8, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 41

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13G

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

La Joya, August 9, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

2,400

2,000

1,600

1,200

800

400

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
42 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13H

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Rio Salado, August 8, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 43

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13I

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Lemitar, August 7, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
44 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13J

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Arroyo del Tajo, June 9, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 45

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13K

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

San Pedro, June 11, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
46 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13L

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Bosque del Apache I, June 12, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
Physical Characteristics and Water-Quality Properties of Mesohabitats over a Range of Streamflows 47

EXPLANATION

Dissolved oxygen

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Specific conductance

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

Temperature

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box

Smallest data value within 1.5 times

the interquartile range below the box

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH

Data value 1.5–3.0 times the

interquartile range outside the box

Median (50th percentile) 

Largest data value within 1.5 times

the interquartile range above the box 

Smallest data value within 1.5 times

the interquartile range below the box 

75th percentile { 25th percentile 

Data value greater than 3.0 times the

interquartile range outside the box

Interquartile

range

pH range for productive, diverse,

and healthy fish communities (Ellis,

1937; McKee and Wolf, 1963;

National Technical Advisory

Committee, 1968; National

Academy of Sciences, 1972)

Upper extent of temperature

range associated with primary

constituent element of critical

habitat (U.S. Fish and Wildlife

Service, 2003)

Thresholds of interest for water-quality

properties 

Acceptable threshold for lower

end of dissolved oxygen

concentration range (Matthews

and Maness, 1979)

NOTE: Middle Rio Grande Bosque Initiative

reach names can be found in table 1.

laf15-CSSJ00-0678_fig 13M

Run

Pool

Isolated

 pool

Forewater

Backwater

Embayment

Flat

Riffle

Mesohabitat type

38

34

30

26

22

18

14

Temperature, in degrees Celsius

Bosque del Apache II, June 13, 2012

16

14

12

10

8

6

4

Dissolved oxygen, in milligrams per liter

2

0

1,600

1,400

1,200

1,000

800

600

400

200

0

10.0

9.5

9.0

8.5

8.0

7.5

7.0

pH

6.5

6.0

Specific conductance, in microsiemens

per centimeter at 25 degrees Celsius

Figure 13. Temperature, dissolved oxygen, specific conductance, and pH in different mesohabitat types at 13 sites on the Middle Rio 

Grande, New Mexico, summer 2012.—Continued
48 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Table 3. Area-weighted mean values of the water-quality properties measured at 13 sites on the Middle Rio Grande, New Mexico, 

summer 2012.

[°C, degrees Celsius; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; ft3/s, cubic feet per second]

Short name for sampling site 

(sites are listed in downstream order)

Date 

sampled

Temperature

(°C )

Specific 

conductance

(μS/cm at 25 °C)

Dissolved 

oxygen

(mg/L)

pH

(standard 

units)

Discharge

(ft3/s)

La Orilla 8/13/2012 23.31 299 7.19 7.98 430

Barelas 8/11/2012 25.70 312 6.79 8.08 93.0

Los Padillas 8/10/2012 25.33 395 6.23 7.81 334

Los Lunas I 6/6/2012 26.68 366 6.91 8.22 258

Los Lunas II 6/7/2012 26.46 386 8.05 8.30 243

Abeytas 6/8/2012 26.46 400 8.60 8.50 179

La Joya 8/9/2012 22.86 837 8.34 8.14 49.5

Rio Salado 8/8/2012 27.19 857 7.07 8.32 37.9

Lemitar 8/7/2012 29.03 1,300 9.13 8.32 4.13

Arroyo del Tajo 6/9/2012 24.95 518 9.03 8.70 140

San Pedro 6/11/2012 21.47 514 8.74 8.79 68.3

Bosque del Apache I 6/12/2012 22.57 501 8.60 8.78 48

Bosque del Apache II 6/13/2012 23.66 640 8.41 8.37 45.7

Area-weighted mean values1 for sites sampled in June 24.61 475 8.33 8.52 140

Area-weighted mean values1 for sites sampled in August 25.57 666 7.46 8.11 158

Area-weighted mean values1 for all sites excluding La Joya, Rio 

Salado, and Lemitar

24.66 433 7.86 8.35 184

Overall area-weighted mean values1 25.05 563 7.93 8.33 149

1

Area-weighted values for water-quality properties by site were made by summing the products of the areal extent of each mesohabitat where water-quality 

properties were measured and the value for that water-quality property within that mesohabitat for all mesohabitats where water-quality properties were 

measured. The resulting sum was then divided by the sum of the areal extents for all mesohabitats where water-quality properties were measured.

Area-weighted specific conductance in the sites upstream 

from La Joya did not exceed 400 μs/cm at 25 °C, and the 

mean specific conductance values at the La Joya, Rio Salado, 

and Lemitar sites (837, 857, and 1,300 μs/cm at 25 °C, 

respectively) were appreciably higher compared to the overall 

mean specific conductance measured for the other 10 sites 

(433 μs/cm at 25 °C; table 3). It is unclear if the disparity in 

mean specific conductance between these three sites (La Joya, 

Rio Salado, and Lemitar) and the remaining sites is based 

on local geology, an influx of surface water with elevated 

specific conductance (from agricultural returns or wastewatertreatment plant effluent, for example), or evapotranspiration 

effects; however, groundwater sources along the western 

margin of the Middle Rio Grande Basin in the area around the 

Rio Puerco, which flows into the Rio Grande just upstream 

from La Joya, tend to have the highest specific conductance 

values (greater than 2,000 μs/cm at 25 °C) in the Middle 

Rio Grande Basin (Plummer and others, 2004). In addition, 

the highest mean specific conductance values (measured at 

the La Joya, Rio Salado, and Lemitar sites) were measured 

(table 3) downstream from the confluence of the Middle 

Rio Grande and the Rio Puerco following 32 consecutive 

days with streamflow recorded at USGS streamflow-gaging 

station 08353000 Rio Puerco near Bernardo, N. Mex. (U.S. 

Geological Survey, 2014), about 3 miles upstream from the 

confluence with the Rio Grande, and the inflows from the 

Rio Puerco were likely more saline compared to the native 

streamflow in the Middle Rio Grande. The four remaining 

sites downstream from Lemitar (Arroyo del Tajo, San Pedro, 

Bosque del Apache I, and Bosque del Apache II) were sampled 

following more than 3 weeks without streamflow in the Rio 

Puerco; this may help explain the substantially lower specific 

conductance values at these 4 sites relative to the 3 sites 

immediately upstream (La Joya, Rio Salado, and Lemitar). 

La Joya, Rio Salado, and Lemitar also had some of the lowest 

measured discharges (49.5, 37.9, and 4.13 ft3/s, respectively) 

(table 3), so evaporative enrichment likely contributed to the 

elevated specific conductance measured at these sites.
Fish Assemblage Composition at the Site Scale 49

The pH typically ranges from about 6.5 to 8.5 in waters 

supporting productive, diverse, and healthy macroinvertebrate 

and fish communities (Ellis, 1937; McKee and Wolf, 1963; 

National Academy of Sciences, 1972). In establishing waterquality criteria for pH, the Ohio River Valley Water Sanitation 

Commission (1955) stated that although fish had been found 

at pH levels ranging between 4 and 10, the safe range was 

between 5 and 9, and maximum productivity generally 

occurred at a pH maintained between 6.5 and 8.5. A pH range 

between 6.5 and 8.5 is highlighted in the box plots associated 

with pH in figure 13.

The pH ranged from 6.5 in a backwater at the La Orilla 

site to 9.72 in an embayment at the Los Lunas I site. The 

largest ranges in pH within a mesohabitat type tended to 

be associated with low-velocity mesohabitats, particularly 

isolated pools, backwaters, and embayments. A small range in 

pH values was measured across all mesohabitat types in the 

downstream part of the study area (with the exception of the 

isolated pools at the Bosque del Apache I site), particularly 

at the Rio Salado, Arroyo del Tajo, San Pedro, Bosque del 

Apache I, and Bosque del Apache II sites. At three of these 

sites (Arroyo del Tajo, San Pedro, and Bosque del Apache I), 

the mean pH values were often outside of the range associated 

with productive, diverse, and healthy macroinvertebrate and 

fish communities (6.5 to 8.5; fig. 13). The mean pH was 

lower at the sites sampled in August (8.11) compared to the 

sites sampled in June (8.52) (table 3). The largest mean pH 

(8.79) was measured at the San Pedro site on June 11, 2012, 

and the smallest mean pH (7.81) was measured at the Los 

Padillas site on August 10, 2012. Lower mean pH values were 

measured at the three sites in and near Albuquerque (La Orilla 

[7.98], Barelas [8.08], and Los Padillas [7.81]) compared to 

any of the 10 remaining sites, which had an overall mean pH 

of 8.44 (table 3). Lower pH associated with the more urban 

sites near Albuquerque may be caused in part by more acidic 

stormwater runoff.

Fish Assemblage Composition at the 

Site Scale

Nineteen species of fish were collected among the 

15 sites and four reaches over both sampling periods (table 

4). Fish-species richness (number of species) among sites that 

were sampled during both sampling periods ranged from 6 at 

Rio Salado to 12 at La Orilla; only four species of fish were 

collected at Peña Blanca during winter 2011–12 (table 4). Fish 

were most abundant at the Lemitar site (1,786 individuals) 

and least abundant at the San Pedro site (275 individuals) 

(table 4). Total CPUE (combined from both sampling periods, 

except at the Peña Blanca and Bernalillo sites, which were 

only sampled during winter 2011–12) at each site ranged from 

13.4 at San Pedro to 211 at Peña Blanca (table 4). The number 

of individuals and the number of fish species collected were 

generally larger at sites in the Angostura and Isleta reaches 

(table 4) compared to the San Acacia reach, with the exception 

of the Lemitar site. Periods of river fragmentation in much 

of the San Acacia reach because of irrigation withdrawals 

during the summer and fall probably account for the fewer 

individuals, fewer fish species, and smaller CPUEs in the San 

Acacia compared to the more upstream reaches during the 

entire year.

Ten of the 19 species (53 percent) collected during winter 

2011–12 and summer 2012 were introduced species (table 

4). More introduced than native species were also found in 

the Middle Rio Grande between near Bernalillo, N. Mex., 

and Elephant Butte Reservoir from 1987 to 1990 (Platania, 

1993). In this study, the native Cyprinella lutrensis (red shiner) 

was the most abundant species collected among all of the 

sites, accounting for about 42 percent of fish collected (table 

4), followed by the introduced Gambusia affinis (western 

mosquitofish) at about 24 percent and native Carpiodes carpio

(river carpsucker) at about 11 percent. All other species of 

fish had relative abundances of less than 10 percent (table 

4). Red shiner was also the most common native species 

collected in the Middle Rio Grande between Bernalillo and 

Elephant Butte Reservoir from 1987 to 1990 (Platania, 1993) 

and again from 2002 to 2004 (Remshardt and Tashjian, 2003). 

Only 1 or 2 individuals were collected across all sites during 

both sampling periods for six species: (1) Ameiurus melas

(black bullhead), (2) Dorosoma cepedianum (gizzard shad), 

(3) Lepomis cyanellus (green sunfish), (4) Morone chrysops

(white bass), (5) Micropterus salmoides (largemouth bass), 

and (6) Lepomis macrochirus (bluegill). About 61 percent of 

fish collected were members of the family Cyprinidae (table 

4), and 69 percent of these fish were accounted for by one 

cyprinid, red shiner (table 4).

Fish-species richness was used in this investigation as 

a standard diversity metric (Ludwig and Reynolds, 1988) 

to compare the fish assemblage among sites at differing 

streamflows during winter 2011–12 and summer 2012 (table 

4). Fish-species richness differed more among sites during 

winter 2011–12 than during summer 2012. The fish-species 

richness varied considerably during winter 2011–12, ranging 

from 1 species at the Los Lunas II site to 9 at the Abeytas 

site (fig. 14; table 4). A much smaller range in fish-species 

richness was found during summer 2012, when a minimum of 

5 species were collected at the Rio Salado site and a maximum 

of 10 species were collected at the Los Lunas I site (fig. 14; 

table 4). Fish-species richness was higher during summer 2012 

compared to winter 2011–12 at all sites that were sampled 

during both periods, with the exception of the Abeytas site, 

where 9 species were collected during both periods, and the 

Los Padillas site, where 7 species were collected during both 

periods (fig. 14; table 4). 

The CPUE per sampling period was highest at the Peña 

Blanca site (211 in winter 2011–12) and lowest at the Los 

Lunas II site (0.15 in winter 2011–12) (table 4, fig. 15). In fact, 

CPUE per sampling period at Peña Blanca was at least double 

the CPUE at all other sites, with the exception of Lemitar, 

which had a CPUE of 151 during summer 2012. The CPUE 
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued [MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI reach name Site short name Sampling period Family Cyprinidae Species Cyprinus carpio Cyprinella lutrensis Hybognathus amarus Rhinichthys cataractae P

p

Species common name Common carp Red shiner Rio Grande silvery minnow Longnose dace Fath

Species abbreviation CYPCAR CYPLUT HYBAMA RHICAT 

Species status I N

N

N

Cochiti Peña Blanca winter 2011–12 Number of individuals 0 0 0 2 

CPUE 0.00 0.00 0.00 0.30 

Angostura

Bernalillo winter 2011–12 Number of individuals 0 402 2 2 

CPUE 0.00 75.71 0.38 0.38 

La Orilla

winter 2011–12 Number of individuals 0 43 21 0 

CPUE 0.00 5.78 2.82 0.00 

summer 2012 Number of individuals 1 124 0 18 

CPUE 0.09 11.39 0.00 1.65 

total Number of individuals 1 167 21 18 

CPUE 0.05 9.11 1.15 0.98 

Barelas

winter 2011–12 Number of individuals 0 2 13 0 

CPUE 0.00 0.16 1.03 0.00 

summer 2012 Number of individuals 2 98 1 0 

CPUE 0.16 7.81 0.08 0.00 

total Number of individuals 2 100 14 0 

CPUE 0.08 3.98 0.56 0.00 

Los 

Padillas

winter 2011–12 Number of individuals 0 9 7 1 

CPUE 0.00 1.42 1.10 0.16 

summer 2012 Number of individuals 1 297 0 41 

CPUE 0.08 25.06 0.00 3.46 

total Number of individuals 1 306 7 42 

CPUE 0.05 16.82 0.38 2.31 

Isleta

Los Lunas I

winter 2011–12 Number of individuals 0 24 4 0 

CPUE 0.00 3.46 0.58 0.00 

summer 2012 Number of individuals 30 781 5 0 

CPUE 2.08 54.16 0.35 0.00 

total Number of individuals 30 805 9 0 

CPUE 1.41 37.70 0.42 0.00 

Los Lunas II

winter 2011–12 Number of individuals 0 1 0 0 

CPUE 0.00 0.15 0.00 0.00 

summer 2012 Number of individuals 8 248 4 0 

CPUE 0.69 21.47 0.35 0.00 

total Number of individuals 8 249 4 0 

CPUE 0.44 13.79 0.22 0.00 

Abeytas

winter 2011–12 Number of individuals 3 149 0 0 

CPUE 0.42 20.78 0.00 0.00 

summer 2012 Number of individuals 4 562 0 0 

CPUE 0.34 47.79 0.00 0.00 

total Number of individuals 7 711 0 0 

CPUE 0.37 37.56 0.00 0.00 

Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.[MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 square 
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued[MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI reach 

name

Site short 

name

Sampling 

period

Family Cyprinidae

Species Cyprinus carpio Cyprinella lutrensis Hybognathus amarus Rhinichthys cataractae P

p

Species common name Common carp Red shiner Rio Grande silvery minnow Longnose dace Fath

Species abbreviation CYPCAR CYPLUT HYBAMA RHICAT 

Species status I N

N

N

Isleta—

Continued

La Joya

winter 2011–12 Number of individuals 0 209 1 0 

CPUE 0.00 37.06 0.18 0.00 

summer 2012 Number of individuals 4 523 0 0 

CPUE 0.43 56.60 0.00 0.00 

total Number of individuals 4 732 1 0 

CPUE 0.27 49.19 0.07 0.00 

Rio Salado

winter 2011–12 Number of individuals 0 38 14 0 

CPUE 0.00 4.29 1.58 0.00 

summer 2012 Number of individuals 0 227 0 0 

CPUE 0.00 29.10 0.00 0.00 

total Number of individuals 0 265 14 0 

CPUE 0.00 15.92 0.84 0.00 

San 

Acacia

Lemitar

winter 2011–12 Number of individuals 0 32 13 0 

CPUE 0.00 6.05 2.46 0.00 

summer 2012 Number of individuals 5 1,461 10 0 

CPUE 0.44 127.93 0.88 0.00 

total Number of individuals 5 1,493 23 0 

CPUE 0.30 89.35 1.38 0.00 

Arroyo del 

Tajo

winter 2011–12 Number of individuals 0 48 75 0 

CPUE 0.00 6.58 10.29 0.00 

summer 2012 Number of individuals 37 26 1 0 

CPUE 2.61 1.84 0.07 0.00 

total Number of individuals 37 74 76 0 

CPUE 1.72 3.45 3.54 0.00 

San Pedro

winter 2011–12 Number of individuals 0 1 5 0 

CPUE 0.00 0.14 0.68 0.00 

summer 2012 Number of individuals 196 4 1 0 

CPUE 14.92 0.30 0.08 0.00 

total Number of individuals 196 5 6 0 

CPUE 9.55 0.24 0.29 0.00 

Bosque del 

Apache I

winter 2011–12 Number of individuals 0 1 2 0 

CPUE 0.00 0.14 0.27 0.00 

summer 2012 Number of individuals 324 16 0 0 

CPUE 32.34 1.60 0.00 0.00 

total Number of individuals 324 17 2 0 

CPUE 18.65 0.98 0.12 0.00 

Bosque del 

Apache II

winter 2011–12 Number of individuals 0 0 6 0 

CPUE 0.00 0.00 0.82 0.00 

summer 2012 Number of individuals 511 29 0 0 

CPUE 40.56 2.30 0.00 0.00 

total Number of individuals 511 29 6 0 

CPUE 25.61 1.45 0.30 0.00 Total no. of individuals 1,126 5,355 185 64 Relative abundance 8.87 42.21 1.46 0.50 
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued [MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI reach name Site short name Sampling period Family Catostomidae Ictaluridae 

Species Carpiodes carpio Catostomus commersonii Ameiurus melas Ictalurus punctatus Pylodictis olivaris Ameiurus natalis 

Species common name River carpsucker White sucker Black bullhead Channel catfish Flathead catfish Yellow bullhead 

Species abbreviation CARCAR CATCOM AMEMEL ICTPUN PYLOLI AMENAT 

Species status

N I I I N I 

Cochiti Peña Blanca winter 2011–12 Number of individuals 0 19 1 0 0 0 

CPUE 0.00 2.87 0.15 0.00 0.00 0.00 

Angostura

Bernalillo winter 2011–12 Number of individuals 0 6 0 2 0 0 

CPUE 0.00 1.13 0.00 0.38 0.00 0.00 

La Orilla

winter 2011–12 Number of individuals 5 0 0 0 0 0 

CPUE 0.67 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 0 0 0 39 19 5 

CPUE 0.00 0.00 0.00 3.58 1.74 0.46 

total Number of individuals 5 0 0 39 19 5 

CPUE 0.27 0.00 0.00 2.13 1.04 0.27 

Barelas

winter 2011–12 Number of individuals 0 0 0 3 0 1 

CPUE 0.00 0.00 0.00 0.24 0.00 0.08 

summer 2012 Number of individuals 38 2 0 40 0 0 

CPUE 3.03 0.16 0.00 3.19 0.00 0.00 

total Number of individuals 38 2 0 43 0 1 

CPUE 1.51 0.08 0.00 1.71 0.00 0.04 

Los Padillas

winter 2011–12 Number of individuals 4 0 0 11 0 0 

CPUE 0.63 0.00 0.00 1.74 0.00 0.00 

summer 2012 Number of individuals 0 0 0 87 13 0 

CPUE 0.00 0.00 0.00 7.34 1.10 0.00 

total Number of individuals 4 0 0 98 13 0 

CPUE 0.22 0.00 0.00 5.39 0.71 0.00 

Isleta

Los Lunas I

winter 2011–12 Number of individuals 1 0 0 0 0 0 

CPUE 0.14 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 503 46 0 1 0 0 

CPUE 34.88 3.19 0.00 0.07 0.00 0.00 

total Number of individuals 504 46 0 1 0 0 

CPUE 23.61 2.15 0.00 0.05 0.00 0.00 

Los Lunas II

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 267 16 0 0 0 0 

CPUE 23.12 1.39 0.00 0.00 0.00 0.00 

total Number of individuals 267 16 0 0 0 0 

CPUE 14.78 0.89 0.00 0.00 0.00 0.00 

Abeytas

winter 2011–12 Number of individuals 4 0 0 1 0 0 

CPUE 0.56 0.00 0.00 0.14 0.00 0.00 

summer 2012 Number of individuals 99 0 0 0 0 1 

CPUE 8.42 0.00 0.00 0.00 0.00 0.09 

total Number of individuals 103 0 0 1 0 1 

CPUE 5.44 0.00 0.00 0.05 0.00 0.05 
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued[MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI reach 

name

Site short 

name

Sampling 

period

Family Catostomidae Ictaluridae 

Species Carpiodes carpio Catostomus commersonii Ameiurus melas Ictalurus punctatus Pylodictis olivaris Ameiurus natalis 

Species common name River carpsucker White sucker Black bullhead Channel catfish Flathead catfish Yellow bullhead 

Species abbreviation CARCAR CATCOM AMEMEL ICTPUN PYLOLI AMENAT 

Species status

N I I I N I 

Isleta—

Continued

La Joya

winter 2011–12 Number of individuals 0 0 0 2 0 0 

CPUE 0.00 0.00 0.00 0.35 0.00 0.00 

summer 2012 Number of individuals 9 0 0 57 0 0 

CPUE 0.97 0.00 0.00 6.17 0.00 0.00 

total Number of individuals 9 0 0 59 0 0 

CPUE 0.60 0.00 0.00 3.97 0.00 0.00 

Rio Salado

winter 2011–12 Number of individuals 0 0 0 2 0 0 

CPUE 0.00 0.00 0.00 0.23 0.00 0.00 

summer 2012 Number of individuals 0 0 0 20 0 1 

CPUE 0.00 0.00 0.00 2.56 0.00 0.13 

total Number of individuals 0 0 0 22 0 1 

CPUE 0.00 0.00 0.00 1.32 0.00 0.06 

San 

Acacia

Lemitar

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 26 0 0 85 0 0 

CPUE 2.28 0.00 0.00 7.44 0.00 0.00 

total Number of individuals 26 0 0 85 0 0 

CPUE 1.56 0.00 0.00 5.09 0.00 0.00 

Arroyo del 

Tajo

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 130 1 0 0 0 0 

CPUE 9.18 0.07 0.00 0.00 0.00 0.00 

total Number of individuals 130 1 0 0 0 0 

CPUE 6.06 0.05 0.00 0.00 0.00 0.00 

San Pedro

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 47 2 0 0 0 0 

CPUE 3.58 0.15 0.00 0.00 0.00 0.00 

total Number of individuals 47 2 0 0 0 0 

CPUE 2.29 0.10 0.00 0.00 0.00 0.00 

Bosque del 

Apache I

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 143 0 0 0 0 0 

CPUE 14.27 0.00 0.00 0.00 0.00 0.00 

total Number of individuals 143 0 0 0 0 0 

CPUE 8.23 0.00 0.00 0.00 0.00 0.00 

Bosque del 

Apache II

winter 2011–12 Number of individuals 0 0 0 0 0 0 

CPUE 0.00 0.00 0.00 0.00 0.00 0.00 

summer 2012 Number of individuals 84 4 0 0 0 0 

CPUE 6.67 0.32 0.00 0.00 0.00 0.00 

total Number of individuals 84 4 0 0 0 0 

CPUE 4.21 0.20 0.00 0.00 0.00 0.00 Total no. of individuals 1,360 96 1 350 32 8 Relative abundance 10.72 0.76 0.01 2.76 0.25 0.06 
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued [MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI reach name Site short name Sampling period Family Centrarchidae Number of individuals 

Species Lepomis cyanellus Pomoxis annularis Morone chrysops Micropterus salmoides Lepomis macrochirus

Species common name Green sunfish White crappie White bass Largemouth bass Bluegill

Species abbreviation LEPCYA POMANN MORCHR MICSAL LEPMAC

Species status I I I I N

Cochiti Peña Blanca winter 2011–12 Number of individuals 0 0 0 0 0 1,394 

CPUE 0.00 0.00 0.00 0.00 0.00

Angostura

Bernalillo winter 2011–12 Number of individuals 0 0 0 0 0 450 

CPUE 0.00 0.00 0.00 0.00 0.00

La Orilla

winter 2011–12 Number of individuals 0 0 0 0 0 107 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 50 0 0 0 479 

CPUE 0.00 4.59 0.00 0.00 0.00

total Number of individuals 0 50 0 0 0 586 

CPUE 0.00 2.73 0.00 0.00 0.00

Barelas

winter 2011–12 Number of individuals 0 0 0 0 0 23 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 530 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 553 

CPUE 0.00 0.00 0.00 0.00 0.00

Los 

Padillas

winter 2011–12 Number of individuals 0 0 0 0 0 34 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 28 0 0 0 770 

CPUE 0.00 2.36 0.00 0.00 0.00

total Number of individuals 0 28 0 0 0 804 

CPUE 0.00 1.54 0.00 0.00 0.00

Isleta

Los Lunas I

winter 2011–12 Number of individuals 0 0 0 0 0 29 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 3 1 0 0 1,490 

CPUE 0.00 0.21 0.07 0.00 0.00

total Number of individuals 0 3 1 0 0 1,519 

CPUE 0.00 0.14 0.05 0.00 0.00

Los Lunas II

winter 2011–12 Number of individuals 0 0 0 0 0 1 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 1 0 817 

CPUE 0.00 0.00 0.00 0.09 0.00

total Number of individuals 0 0 0 1 0 818 

CPUE 0.00 0.00 0.00 0.06 0.00

Abeytas

winter 2011–12 Number of individuals 1 2 0 0 0 165 

CPUE 0.14 0.28 0.00 0.00 0.00

summer 2012 Number of individuals 0 1 0 0 1 1,216 

CPUE 0.00 0.09 0.00 0.00 0.09

total Number of individuals 1 3 0 0 1 1,381 

CPUE 0.05 0.16 0.00 0.00 0.05
Table 4. Fish species, number of individuals collected, number of species of fish, and catch per unit effort from 15 sites distributed among four reachNew Mexico, winter 2011–12 and summer 2012.—Continued[MRGBI, Middle Rio Grande Bosque Initiative; I, Introduced; N, Native; m2, square meters; CPUE, catch per unit of seining effort (number of individuals caught per 100 squar

MRGBI 

reach name

Site short 

name

Sampling 

period

Family Centrarchidae

Number of 

individuals

Species Lepomis cyanellus Pomoxis annularis Morone chrysops Micropterus salmoides Lepomis macrochirus

Species common name Green sunfish White crappie White bass Largemouth bass Bluegill

Species abbreviation LEPCYA POMANN MORCHR MICSAL LEPMAC

Species status I I I I N

Isleta—

Continued

La Joya

winter 2011–12 Number of individuals 0 0 0 0 0 218 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 791 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 1,009 

CPUE 0.00 0.00 0.00 0.00 0.00

Rio Salado

winter 2011–12 Number of individuals 0 0 0 0 0 74 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 417 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 491 

CPUE 0.00 0.00 0.00 0.00 0.00

San Acacia

Lemitar

winter 2011–12 Number of individuals 0 0 0 0 0 57 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 1,729 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 1,786 

CPUE 0.00 0.00 0.00 0.00 0.00

Arroyo del 

Tajo

winter 2011–12 Number of individuals 0 0 0 0 0 125 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 290 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 415 

CPUE 0.00 0.00 0.00 0.00 0.00

San Pedro

winter 2011–12 Number of individuals 0 0 0 0 0 6 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 269 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 275 

CPUE 0.00 0.00 0.00 0.00 0.00

Bosque del 

Apache I

winter 2011–12 Number of individuals 0 0 0 0 0 3 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 528 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 531 

CPUE 0.00 0.00 0.00 0.00 0.00

Bosque del 

Apache II

winter 2011–12 Number of individuals 0 0 0 0 0 6 

CPUE 0.00 0.00 0.00 0.00 0.00

summer 2012 Number of individuals 0 0 0 0 0 670 

CPUE 0.00 0.00 0.00 0.00 0.00

total Number of individuals 0 0 0 0 0 676 

CPUE 0.00 0.00 0.00 0.00 0.00Total no. of individuals 1 84 1 1 1 12,688 Relative abundance 0.01 0.66 0.01 0.01 0.01
56 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

* *

EXPLANATION

Sampling periods

Winter 2011–12

Summer 2012

*Site was not sampled in summer 2012

NOTE: Fish-species richness refers to the number

of fish species that were collected; it is dimensionless.

laf15-CSSJ00-0678_fig 14

Sampling site (table 1)

0

2

4

6

8

10

12

Fish-species richness

Isleta

reach

San Acacia

reach

Angostura

reach

Cochiti

reach

Peña Blanca

La Orilla

Barelas

Los Padillas

La Joya

Rio Salado

San Pedro

Arroyo del Tajo

Bernalillo

Abeytas

Los Lunas II

Los Lunas I

Lemitar

Bosque del

Apache I

Bosque del

Apache II

Figure 14. Fish-species richness (number of fish species) collected from 15 sites on the Middle Rio Grande distributed among four 

reaches of the Middle Rio Grande, New Mexico, winter 2011–12 and summer 2012.
Fish Assemblage Composition at the Site Scale 57

0

50

100

150

200

250

Isleta

reach

San Acacia

reach

Angostura

reach

Cochiti

reach

* *

Catch per unit effort 

(number of fish per 100 square meters)

Sampling site (table 1)

Peña Blanca

La Orilla

Barelas

Los Padillas

La Joya

Rio Salado

San Pedro

Arroyo del Tajo

Bernalillo

Abeytas

Los Lunas II

Los Lunas I

Lemitar

Bosque del

Apache I

Bosque del

Apache II

laf15-CSSJ00-0678_fig 15

EXPLANATION

Sampling periods

Winter 2011–12

Summer 2012

*Site was not sampled in summer 2012

Figure 15. Catch per unit effort from 15 Middle Rio Grande sites distributed among four reaches of the Middle Rio Grande, New 

Mexico, winter 2011–12 and summer 2012.
58 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

was lower in winter 2011–12 relative to summer 2012 at all 

of the sites that were sampled during both sampling periods. 

The higher CPUEs during summer 2012 at the majority of 

sites that were sampled during both sampling periods can be 

explained, at least in part, by improved sampling efficiency 

with respect to easier access to specific mesohabitats within 

the river channel during the summer 2012, when depths were 

shallower and streamflows were lower compared to winter 

2011–12 (fig. 11). One other factor contributing to higher 

CPUEs in summer 2012 relative to winter 2011–12 is that 

summer is the reproductive season for most fish species, so 

their numbers and densities tend to be higher in summer.

Fish Assemblage Composition at the 

Mesohabitat Scale

The relations between fish assemblage composition 

(that is, total abundance, which refers to the number of 

individuals of each species that were collected) and selected 

environmental variables (physical characteristic data collected 

at the mesohabitat scale [depth, velocity, and substrate particle 

size] and mesohabitat types) were explored by using CCA 

(figs. 16 and 17). Each orange triangle in the CCA represents 

a species’ central tendency related to environmental variables 

graphically displayed on ordination gradients (axes 1 and 2 in 

figs. 16 and 17). Species that plotted in close proximity to one 

another tended to be sampled in similar mesohabitat types with 

similar environmental variables (ter Braak and Verdonschot, 

1995). To minimize effects of highly skewed distributions of 

the number of individuals of each species (total abundance) 

in the CCA models, data were logarithmically transformed 

(base 10), increasing the number of values (n) by 1. Fish 

species that were collected infrequently were downweighted 

to prevent them from plotting as misleading outliers in the 

CCA model (Gauch, 1982), and species with fewer than 10 

individuals were removed from the CCA model output. The 

chi-square distances for individual species in the CCA model 

are weighted by the inverse of the number of individuals 

of each species that are collected. As a result, species that 

are collected infrequently tend to be overemphasized in the 

CCA model, and downweighting was used to correct this 

overemphasis (Lepš and Šmilauer, 2003). To test significance 

(p<0.05) of variation, a Monte Carlo randomization test with 

5,000 permutations was performed on the CCA model (ter 

Braak and Šmilauer, 2002).

Environmental variables explained 8 percent (p=0.48) 

of the variability in the Middle Rio Grande fish assemblage 

during winter 2011–12 (fig. 16). Environmental variables 

strongly associated with axis 1 were forewater mesohabitats 

(0.47), cobbles substrates (0.45), sand substrates (-0.53), 

and run mesohabitats (-0.50). Environmental variables 

strongly associated with axis 2 were pool mesohabitats 

(0.58), riffle mesohabitats (0.45), and depth (-0.40). Among 

fish associated with axes 1 and 2, western mosquitofish was 

weakly associated with pool and forewater mesohabitats 

with clay, silt, and cobble substrates; Platygobio gracilis

(flathead chub) and Ictalurus punctatus (channel catfish) were 

weakly associated with relatively high velocities (qualitative 

descriptors are derived from synthetic gradients extracted from 

CCAs) and run mesohabitats, and Rio Grande silvery minnow 

were weakly associated with sand substrates, relatively 

moderate velocities, and relatively shallow depths. 

Environmental variables explained 14 percent (p<0.01) 

of the variability in the Middle Rio Grande fish assemblage 

during summer 2012 (fig. 17). Environmental variables 

strongly associated with axis 1 were velocity (0.94), run 

habitats (0.63), sand substrates (0.58), silt and clay substrates 

(-0.61), backwater habitats (-0.40), and pool habitats (-0.38). 

Environmental variables strongly associated with axis 2 were 

gravel substrates (0.50), riffle habitats (0.36), embayment 

habitats (-0.53), and depth (-0.52). Among fish associated 

with axes 1 and 2, channel catfish, Pylodictis olivaris (flathead 

catfish), and Rio Grande silvery minnow were associated with 

run mesohabitats, relatively high velocities, sand substrates, 

and relatively moderate depths. Rhinichthys cataractae

(longnose dace) and flathead chub were associated with riffle 

and flat mesohabitats, relatively high velocities, and sand and 

gravel substrates at relatively shallow depths. Cyprinus carpio

(common carp), western mosquitofish, Pimephales promelas

(fathead minnow), and river carpsucker were associated with 

backwater and pool mesohabitats, relatively low velocities, silt 

and clay substrates, and relatively shallow to moderate depths. 

Aside from a single pool at the Los Lunas I site in which 

7 fish species were collected, no more than 4 fish species were 

collected in any other mesohabitat of any type during winter 

2011–12 (fig. 18A). Fish-species richness per mesohabitat 

ranged from 0 to 4 in riffles, runs, and isolated pools and was 

slightly less in flats (0 to 3) and margin pools (0 to 2). Mean 

fish-species richness during winter 2011–12 was highest in 

pools (1.23), and only two of the mesohabitat types sampled 

(pools and isolated pools) had a mean fish-species richness 

of at least 1 (fig. 18A). In contrast, during summer 2012, all 

mesohabitat types except for riffles had mean fish-species 

richness values greater than 1, and two mesohabitat types 

(pools and isolated pools) had mean fish-species richness 

values greater than 2 (fig. 18B). The mean fish-species 

richness was 2.33 in pools and 2.08 in isolated pools during 

summer 2012 (fig. 18B). The ranges of fish-species richness 

were larger in summer 2012 than in winter 2011–12 for 4 of 

the 6 mesohabitat types (runs, isolated pools, margin pools, 

and flats), and the upper end of the ranges for the 2 remaining 

mesohabitat types (riffles and pools) during winter 2011–12 

were each represented by a single mesohabitat and include a 

riffle at the La Orilla site and the previously mentioned single 

pool at the Los Lunas I site. The mean fish-species richness 

was greater in summer 2012 than in winter 2011–12 for each 

mesohabitat type (fig. 18), and the overall fish-species richness 
Fish Assemblage Composition at the Mesohabitat Scale 59

laf15-CSSJ00-0678_fig 16

-0.40 0.00 0.40

Rio Grande

silvery minnow (152)

Depth

Velocity

Riffle

Run

Pool

Forewater Backwater

Flat

Red shiner (737)

Flathead chub (44)

Channel catfish (19)

Western mosquitofish (42)

Axis 1

River carpsucker (12)

Gravel

Sand

Silt and clay

-0.60 -0.20 0.20 0.60

-0.60

-0.20

0.60

0.20

0.00

-0.40

0.40 Isolated

pool

Axis 2

-0.60

-0.20

0.60

0.20

0.00

-0.40

0.40

Cobble

EXPLANATION

Environmental

variables

Sediment categories (size in millimeters)—

 Modified from Wentworth (1922) and

 Guy (1969)

Gravel (greater than 2 and less than

 or equal to 64)

Sand (greater than 0.0625 and less than

 or equal to 2)

Silt and clay (less than or equal to 0.0625)

Cobble (greater than 64 and less than or

 equal to 256)

Fish species

Red shiner (737)

NOTE: The overall similarity of fish species to

mesohabitat type and selected environmental variables

(depth, velocity, and substrate size) is graphically

depicted by using species and mesohabitat type scores

arrayed along synthetic ordination axes derived by the

canonical correspondence analysis (CCA). Each species

point corresponds to the weighted average score of the axis

scores of the mesohabitats where the species occurred.

Scores for mesohabitats correspond to the coordinates of the

mesohabitats on the best or, in this case, first two axes derived

by the CCA. The environmental variables are displayed as

arrows from the origin of the diagram, the coordinates of

which are the correlations of the variable with the axes

(ter Braak and Verdonschot, 1995). Scientific names

corresponding to the common names shown here are

provided in table 4.

Figure 16. Correlation between fish species and a combination of mesohabitats and environmental variables at 15 sites distributed 

among four reaches of the Middle Rio Grande, New Mexico, winter 2011–12.
60 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

-0.80 -0.40 0.00 0.40 0.80

Rio Grande

silvery minnow (22)

Depth

Velocity

Riffle

Pool Run

Embayment

Forewater

Backwater

Flat

Red shiner (4,396)

Common carp (1,123)

Flathead chub (736)

Longnose dace (59)

White sucker (71)

Channel catfish (329)

Flathead catfish (32)

Western mosquitofish (1,600)

Axis 1

River carpsucker (1,346)

Gravel

Sand

Silt and clay

-1.00 -0.60 -0.20 0.20 0.60 1.00

-0.60

-0.20

0.60

0.20

0.00

-0.40

0.40

-0.80

0.80

Axis 2

-0.60

-0.20

0.60

0.20

0.00

-0.40

0.40

-0.80

0.80

Isolated

pool

Fathead minnow (189)

White crappie (82)

laf15-CSSJ00-0678_fig 17

NOTE: The overall similarity of fish species to

mesohabitat type and selected environmental variables

(depth, velocity, and substrate size) is graphically

depicted by using species and mesohabitat type scores

arrayed along synthetic ordination axes derived by the

canonical correspondence analysis (CCA). Each species

point corresponds to the weighted average score of the axis

scores of the mesohabitats where the species occurred.

Scores for mesohabitats correspond to the coordinates of the

mesohabitats on the best or, in this case, first two axes derived

by the CCA. The environmental variables are displayed as

arrows from the origin of the diagram, the coordinates of

which are the correlations of the variable with the axes

(ter Braak and Verdonschot, 1995). Scientific names

corresponding to the common names shown here are

provided in table 4.

White sucker (71)

EXPLANATION

Environmental

variables

Sediment categories (size in millimeters)—

 Modified from Wentworth (1922) and

 Guy (1969)

Gravel (greater than 2 and less than

 or equal to 64)

Sand (greater than 0.0625 and less than

 or equal to 2)

Silt and clay (less than or equal to 0.0625)

Cobble (greater than 64 and less than or

 equal to 256)

Fish species

Figure 17. Correlation between fish species and a combination of mesohabitats and environmental variables at 13 sites distributed 

among four reaches of the Middle Rio Grande, New Mexico, summer 2012. 
Fish Assemblage Composition at the Mesohabitat Scale 61

laf15-CSSJ00-0678_fig 18

0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

Fish-species richness

Riffle Run Pool Isolated pool Margin pool* Flat

A. Winter 2011–12

B. Summer 2012

Mesohabitat type

 Mean 

EXPLANATION

 Maximum 

 Minimum 

*Margin pool includes forewaters, 

backwaters, and embayments as 

depicted in figure 7 

Figure 18. Fish-species richness by mesohabitat type measured at 15 Middle Rio Grande sites distributed among four reaches of the 

Middle Rio Grande, New Mexico during, A, winter 2011–12, and B, summer 2012. 
62 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

across all mesohabitat types was 0.62 during winter 2011–12 

compared to 1.49 during summer 2012. In other words, almost 

one additional fish species, on average, was collected per 

mesohabitat sampled during summer 2012 compared to winter 

2011–12.

Catch per unit effort ranged from zero to less than 

380 fish per 100 m2 in 5 of the 6 mesohabitats (riffles, pools, 

isolated pools, margin pools, and flats) sampled during winter 

2011–12 (fig. 19A). Only runs had a maximum CPUE range 

that exceeded 380 fish per 100 m2, reaching as high as 1,478 

fish per 100 m2 in a run at the Bernalillo site (fig. 19A), but the 

fact that runs made up 58 percent of the mesohabitats sampled 

during winter 2011–12 may provide some justification for 

this disparity in CPUE between the different mesohabitat 

types. The highest mean CPUE during winter 2011–12 was in 

isolated pools (54.3 fish per 100 m2), whereas the lowest was 

in flats (18.9 fish per 100 m2) (fig. 19A). Ranges in CPUE were 

higher in summer 2012 relative to winter 2011–12 in each 

mesohabitat type sampled, reaching as high as 4,333 fish per 

100 m2 in a run at Rio Salado (fig. 19B). As in winter 2011–12, 

the highest mean CPUE during summer 2012 was in isolated 

pools (233 fish per 100 m2), whereas the lowest was in flats 

(29.6 fish per 100 m2) (fig. 19B). Overall mean CPUE per 

mesohabitat across all mesohabitat types was 29.1 fish per 100 

m2 during winter 2011–12 compared to 85.3 fish per 100 m2

during summer 2012. In other words, almost three times as 

many fish, on average, were collected per unit sampling effort 

during summer 2012 compared to winter 2011–12.

Four species of minnows (red shiner, Rio Grande silvery 

minnow, fathead minnow, and flathead chub) (referred to 

hereinafter as the “four minnow species of interest”) were 

selected to compare preferred mesohabitat characteristics 

because all are small-bodied minnows and because more 

than 200 individuals (a sufficient sample size for evaluating 

preferences for mesohabitat physical characteristics) of each 

of these species were collected. Comparisons were made with 

regards to depth, velocity, and dissolved oxygen concentration 

among the Angostura, Isleta, and San Acacia reaches. Depth, 

velocity, and dissolved oxygen values used in this comparison 

were from measurements collected from the center of each 

seine haul. The 163 Rio Grande silvery minnow individuals 

collected during winter 2011–12 were distributed as 43 

individuals from the Angostura reach, 19 individuals from the 

Isleta reach, and 101 individuals from the San Acacia reach. 

The 22 Rio Grande silvery minnow individuals collected 

during summer 2012 were distributed as 1 individual from 

the Angostura reach, 9 individuals from the Isleta reach, and 

12 individuals from the San Acacia reach. The number of 

individuals of the different species shown above each of the 

box plots in figures 20–22 does not necessarily match the 

number of individuals of those same species listed in table 4 

and in the geodatabase; this is because depth, velocity, and 

dissolved oxygen data were not collected at all locations 

where fish were collected. If depth, velocity, and dissolved 

oxygen data could not be linked to a fish, then that fish could 

not be included in figures 20–22. 

During winter 2011–12, red shiner were collected across 

the largest range of depths (0.02–4.31 ft) of the four minnow 

species of interest across the study area, and fathead minnow 

were collected in the narrowest range of depths (0.34–0.70 ft), 

most likely the result of the comparatively small sample size 

(n=8) in winter 2011–12 for this species (fig. 20). The broad 

range of depths associated with the collections of red shiner 

are probably the result of both the large sample size for this 

species (n=626 when associated depth and velocity data were 

also collected) in conjunction with the fact that red shiners are 

generalists (U.S. Geological Survey, 2002), which means that 

they can thrive in a wide array of environmental conditions. The 

largest ranges in depths for each of the four minnow species of 

interest occurred in the Isleta reach, with the exception of the 

fathead minnow, which had only a single individual collected 

in the Isleta reach during winter 2011–12. Red shiner were 

collected across the largest range of depths (0.05–3.4 ft) of 

the four minnow species of interest during summer 2012. Rio 

Grande silvery minnow were collected in the narrowest range of 

depths (0.30–2.1 ft), most likely as a result of the comparatively 

small sample size (n=22) in the summer of 2012 for this species 

(fig. 20). As in winter 2011–12, the broad range of depths 

associated with the collections of red shiner are probably the 

result of a large sample size (n=4,396) for this species and its 

status as a generalist. 

During winter 2011–12, red shiner were collected in the 

broadest range of velocities (0.0–4.31 ft/s) across the study 

area of the four minnow species of interest (fig. 21). Only 

the magnitudes of velocity measurements were considered in 

terms of fish preferences with respect to velocity (fig. 21); Rio 

Grande silvery minnow had the narrowest range (0.0–3.18 ft/s). 

During summer 2012, the flathead chub was collected in the 

largest range of velocities (0.0–3.44 ft/s) across the study area 

(not including the Peña Blanca and Bernalillo sites) of the four 

minnow species of interest (fig. 21). Rio Grande silvery minnow 

had the narrowest range (0.02–1.51 ft/s), again most likely the 

result of the small sample size for this species in the summer 

of 2012. Median velocity preferences were highest for all four 

minnow species of interest in the Angostura reach relative to the 

Isleta and San Acacia reaches.

The range of velocities associated with the collection of 

Rio Grande silvery minnow in this study is at the upper end of 

the distribution of velocities for this species, as determined in 

previous studies (Dudley and Platania, 1996, 1997). More than 

95 percent of Rio Grande silvery minnows collected as part 

of the first of these Dudley and Platania studies (1996) were 

collected at velocities less than or equal to 1.00 ft3/s (fig. 21G), 

and approximately 95 percent of Rio Grande silvery minnows 

collected as part of the second of these Dudley and Platania 

studies (1997) were collected at velocities less than or equal to 

0.67 ft3/s (fig. 21H). In contrast, the overall median velocity at 

which Rio Grande silvery minnows were collected as part of 

this investigation was 1.01 ft3/s. The median velocity at which 

Rio Grande silvery minnows were collected in winter 2011–12 

was 1.21 ft3/s, whereas the median velocity in summer 2012 

was 0.91 ft3/s.
Fish Assemblage Composition at the Mesohabitat Scale 63

laf15-CSSJ00-0678_fig 19

0

200

400

600

800

1,000

1,200

1,400

1,600

Riffle Run Pool Isolated pool Margin pool* Flat

0

200

400

600

800

1,000

1,200

1,400

1,600 (4,333)

A. Winter 2011–12 

B. Summer 2012

Catch per unit effort

(number of fish per 100 square meters)

Mesohabitat type

 Mean 

EXPLANATION

 Maximum 

 Minimum 

*Margin pool includes forewaters, 

backwaters, and embayments as 

depicted in figure 7 

Figure 19. Catch per unit effort by mesohabitat type from 15 Middle Rio Grande sites distributed among four reaches of the Middle Rio 

Grande, New Mexico, A, winter 2011–12, and B, summer 2012. 
64 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

laf15-CSSJ00-0678_fig 20

EXPLANATION

Median (50th percentile) 

Maximum 

Minimum 

75th percentile 

25th percentile 

{

Fish species common name

CYPLUT

HYBAMA

PIMPRO

PLAGRA

Depth

Red shiner

Rio Grande silvery minnow

Fathead minnow

Flathead chub

Interquartile

range

(10) Number of individuals used

in box plot construction 

C. San Acacia, winter 2011–12

CYPLUT HYBAMA PIMPRO PLAGRA

Species

Depth, in feet

CYPLUT HYBAMA PIMPRO PLAGRA

Species

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

F. San Acacia, summer 2012

(70) (79) (0) (10) (1,536) (12) (45) (137)

B. Isleta, winter 2011–12

Depth, in feet

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

E. Isleta, summer 2012

(295) (18) (1) (19) (2,341) (9) (110) (35)

Depth, in feet

A. Angostura, winter 2011–12

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

D. Angostura, summer 2012

(261) (40) (7) (10) (519) (1) (34) (563)

NOTE: Scientific names corresponding to the

common names shown here are provided in

table 4.

Figure 20. Depths associated with the collection of selected minnow species from three reaches of the Middle

Rio Grande, New Mexico, during winter 2011–12 A, Angostura; B, Isleta; and C, San Acacia; and during summer 2012 D, Angostura;

E, Isleta; and F, San Acacia. 
Fish Assemblage Composition at the Mesohabitat Scale 65

laf15–CSSJ00–0678_fig 21

EXPLANATION

Fish species common name

Velocity

Collection fequencies of Rio Grande silvery

minnows as a function of velocity

from Dudley and Platania (1996)

from Dudley and Platania (1997)

CYPLUT

HYBAMA

PIMPRO

PLAGRA

Red shiner

Rio Grande silvery minnow

Fathead minnow

Flathead chub

(10) Number of individuals used

in box plot construction 

Median (50th percentile) 

Maximum 

Minimum 

75th percentile 

25th percentile 

{ Interquartile

range

NOTE: Scientific names corresponding to the

common names shown here are provided in

table 4. 

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

CYPLUT HYBAMA PIMPRO PLAGRA

Species

CYPLUT HYBAMA PIMPRO PLAGRA

Species

C. San Acacia, winter 2011–12 F. San Acacia, summer 2012

(70) (79) (0) (10) (1,536) (12) (45) (137)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5 B. Isleta, winter 2011–12 E. Isleta, summer 2012

(295) (18) (1) (19) (2,341) (9) (110) (35)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

A. Angostura, winter 2011–12 D. Angostura, summer 2012

(261) (40) (7) (10) (519) (1) (34) (563)

0

50

40

30

20

10

Velocity, in feet per second

0

0.03–0.34

0.35–0.67

0.68–1.00

1.01–1.32

1.33–1.65

1.66–1.98

1.99–2.31 

2.32–2.64

2.65–2.97

2.98–3.30

H.

0

50

40

30

20

10

 Collection frequency, in percent

G.

Velocity, in feet per second Velocity, in feet per second Velocity, in feet per second

Figure 21. Velocities associated with the collection of selected minnow species from three reaches of the Middle Rio Grande, New 

Mexico, during winter 2011-12, A, Angostura; B, Isleta; and C, San Acacia and during summer 2012; D, Angostura; E, Isleta; and F, San 

Acacia; and collection frequencies of Rio Grande silvery minnows as a function of velocity from G, Dudley and Platania (1996); and H, 

Dudley and Platania (1997).
66 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Like depth and velocity, dissolved oxygen was collected 

at the center of each seine haul at the midpoint of the water 

column. Median dissolved oxygen concentrations for the 

four minnow species of interest exhibited a general upward 

pattern in a downstream direction from the Angostura reach 

to the San Acacia reach (fig. 22). Median dissolved oxygen 

concentrations for the four minnow species of interest ranged 

from 6.32 to 7.08 mg/L in the Angostura reach, from 7.14 

to 8.83 mg/L in the Isleta reach, and from 7.72 to 9.05 mg/L 

in the San Acacia reach. This is most likely the result of 

the comparatively large number of shallow, low-velocity 

mesohabitats including margin pools and isolated pools in 

the San Acacia reach that contained a large amount of algae 

when the sites were sampled in summer 2012. Although the 

ranges of dissolved oxygen concentrations associated with the 

collection of red shiner and Rio Grande silvery minnow were 

quite different because red shiners were more widespread, 

median dissolved oxygen concentrations were similar 

(particularly in the Isleta and San Acacia reaches) for both 

species on a reach basis. It should also be noted that because 

the water-quality monitoring methodology did not capture the 

diel minima and maxima, it was not possible to accurately 

quantify the species-specific range of preferred dissolved 

oxygen concentrations.
Fish Assemblage Composition at the Mesohabitat Scale 67

laf15–CSSJ00–0678_fig 22

C. San Acacia

Dissolved oxygen, in milligrams per liter

0

2

4

6

8

10

12

14

16

CYPLUT HYBAMA PIMPRO PLAGRA

Species

CYPLUT HYBAMA PIMPRO PLAGRA

Species

(1,536) (12) (45) (137)

B. Isleta

Dissolved oxygen, in milligrams per liter

0

2

4

6

8

10

12

14

16

(2,341) (9) (110) (35)

Dissolved oxygen, in milligrams per liter

0

2

4

6

8

10

12

14

16

(519) (1) (34) (563)

A. Angostura

EXPLANATION

Median (50th percentile) 

Maximum 

Minimum 

75th percentile 

25th percentile 

{

Fish species common name

CYPLUT

HYBAMA

PIMPRO

PLAGRA

Dissolved oxygen

Red shiner

Rio Grande silvery minnow

Fathead minnow

Flathead chub

Interquartile

range

(10) Number of individuals used

in box plot construction 

NOTE: Scientific names corresponding to the

common names shown here are provided in

table 4.

Figure 22. Dissolved oxygen concentrations associated with the collection of selected minnow species during summer 2012 from 

three reaches of the Middle Rio Grande, New Mexico, A, Angostura, B, Isleta, and C, San Acacia.
68 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Summary

In winter 2011–12 and summer 2012, the U.S. Geological 

Survey (USGS), in cooperation with the U.S. Army Corps 

of Engineers, Albuquerque District and the U.S. Fish and 

Wildlife Service New Mexico Fish and Wildlife Conservation 

Office in Albuquerque, N. Mex., evaluated the physical 

characteristics and fish assemblage composition of available 

mesohabitats over a range of streamflows at 15 sites on the 

Middle Rio Grande in New Mexico. The fish assemblage 

of the Middle Rio Grande includes several minnow species 

adapted to hydrologically variable but seasonably predictable 

rivers, including the Hyboganthus amarus (Rio Grande 

silvery minnow). Gaining a better understanding of habitat 

usage by the Rio Grande silvery minnow, a federally listed 

endangered species, was the impetus for studying physical 

characteristics and fish assemblages in the Middle Rio 

Grande during different streamflow conditions. Data were 

collected at all 15 sites during winter 2011–12 (moderate 

streamflow), and a subset was collected at the 13 most 

downstream sites in summer 2012 (low streamflow). Sites 

were grouped into four river reaches separated by diversion 

dams listed in downstream order (names of the diversion 

dams are followed by short names of the sites nearest each 

dam in parentheses, listed in downstream order): (1) Cochiti 

(Peña Blanca), (2) Angostura (Bernalillo, La Orilla, Barelas, 

Los Padillas), (3) Isleta (Los Lunas I, Los Lunas II, Abeytas, 

La Joya, Rio Salado), and (4) San Acacia (Lemitar, Arroyo 

del Tajo, San Pedro, Bosque del Apache I, and Bosque del 

Apache II). Stream habitat was mapped in the field by using a 

geographic information system in conjunction with a Global 

Positioning System. Fish assemblage was determined during 

both streamflow regimes, and fish were collected by seining 

in each mesohabitat where physical characteristic data (depth, 

velocity, dominant substrate type and size, and percent 

embeddedness) and water-quality properties (temperature, 

dissolved oxygen, specific conductance, and pH; during 

summer 2012 only) were measured.

Measured depths and velocities varied greatly by 

mesohabitat type, site, and sampling period (winter 2011–12 

or summer 2012). When an area-weighting factor was applied 

to the depth and velocity, the sites that were investigated in 

both winter 2011–12 and summer 2012 tended to have smaller 

mean depths and mean velocities during summer 2012, when 

discharges tended to be lower, compared to winter 2011–12. 

Discharge measurements that were made in the field ranged 

from 552 cubic feet per second (ft3/s) at Peña Blanca on 

November 11, 2011, to 991 ft3/s at La Joya on November 

30, 2011, in winter 2011–12, and ranged from 4.13 ft3/s at 

Lemitar on August 7, 2012, to 430 ft3/s at La Orilla on August 

13, 2012. Streambed sediments at Peña Blanca and Bernalillo 

were predominantly coarse gravels and cobble. Downstream 

from these two sites, the Rio Grande is characterized by a 

broad, low-gradient channel dominated by smaller grained bed 

materials, primarily sand with some silt and clay.

Water-quality properties were only collected during 

summer 2012, when low-streamflow conditions existed 

and water-quality properties were thought to be potentially 

most limiting to aquatic life. Area-weighted mean water 

temperatures tended to be higher at the sites that were sampled 

in August (25.57 degrees Celsius [°C]) compared to June 

(24.61 °C). The highest area-weighted mean water temperature 

at a given site (29.03 °C) was measured at the Lemitar site 

on August 7, 2012, coincident with the lowest measured 

discharge (4.13 ft3/s). Area-weighted mean dissolved oxygen 

concentrations tended to be lower in August (7.46 milligrams 

per liter [mg/L]) compared to June (8.33 mg/L). The highest 

area-weighted mean dissolved oxygen concentration 

(9.13 mg/L) was measured at the Lemitar site on August 7, 

2012, and the lowest area-weighted mean dissolved oxygen 

concentration (6.23 mg/L) was measured at the Los Padillas 

site on August 10, 2012. Specific conductance ranged from 

175 microsiemens per centimeter [μs/cm] at 25 °C in an 

isolated pool at the La Orilla site to 2,246 μs/cm at 25 °C in an 

isolated pool at the La Joya site. Elevated specific conductance 

in isolated pools may be caused by either the evaporative 

concentration of solutes or by the mixing of less saline surface 

water with more saline groundwater from the hyporheic zone. 

Area-weighted specific conductance in the sites upstream from 

La Joya did not exceed 400 μs/cm at 25 °C, whereas the areaweighted mean specific conductance at La Joya (837 μs/cm at 

25 °C), Rio Salado (857 μs/cm at 25 °C), and Lemitar (1,300 

μs/cm at 25 °C) were all well above the average of the areaweighted means for the 10 remaining sites (433 μs/cm at 25 

°C). The pH ranged from 6.5 in a backwater at the La Orilla 

site to 9.72 in an embayment at the Los Lunas I site. Lower 

area-weighted mean pH values were measured at the three 

sites in and near Albuquerque (La Orilla [7.98], Barelas [8.08], 

and Los Padillas [7.81]) compared to any of the 10 remaining 

sites, which had an overall mean pH of 8.44.

Nineteen species of fish were collected among the 15 

sites and four reaches over both sampling periods; 10 of these 

19 species are introduced. Fish-species richness (total number 

of fish species collected at each site during each sampling 

event) among sites that were sampled during both sampling 

periods ranged from 6 at Rio Salado to 12 at La Orilla. Fish 

were most abundant at the Lemitar site (1,786 individuals) 

and least abundant at the San Pedro site (275 individuals). The 

native Cyprinella lutrensis (red shiner) was the most abundant 

species collected among all of the sites, accounting for about 

42 percent of fish collected. Fish-species richness and catch 

per unit effort (CPUE) were higher (or equivalent) at all sites 

during summer 2012 compared to winter 2011–12.

The relations between fish assemblage composition 

(that is, total abundance, which refers to the number of 

individuals of each species that were collected) and selected 

environmental variables (physical characteristic data collected 

at the mesohabitat scale [depth, velocity, and substrate 

particle size], and mesohabitat types) were explored by using 

canonical correspondence analysis. Environmental variables 

explained 8 percent (p=0.48) of the variability in the Middle 
References 69

Rio Grande fish assemblage during winter 2011–12, and 

Rio Grande silvery minnow were weakly associated with 

sand substrates, relatively moderate velocities (qualitative 

descriptors are derived from synthetic gradients extracted 

from CCAs), and relatively shallow depths. Environmental 

variables explained 14 percent (p<0.01) of the variability in 

the Middle Rio Grande fish assemblage during summer 2012, 

when Rio Grande silvery minnow were associated with run 

mesohabitats, relatively high velocities, sand substrates, and 

relatively moderate depths.

Aside from a single pool at the Los Lunas I site in 

which 7 fish species were collected, no more than 4 fish 

species were collected in any other mesohabitat of any type 

during winter 2011–12. The mean fish-species richness 

was greater in summer 2012 than in winter 2011–12 for 

each mesohabitat type, and the overall fish-species richness 

across all mesohabitat types was 0.62 during winter 2011–12 

compared to 1.49 during summer 2012. In other words, almost 

one additional fish species, on average, was collected per 

mesohabitat sampled during summer 2012 compared to winter 

2011–12.

The highest mean CPUE during winter 2011–12 was in 

isolated pools (54.3 fish per 100 square meters [m2]), whereas 

the lowest was in flats (18.9 fish per 100 m2). Ranges in CPUE 

were higher in summer 2012 relative to winter 2011–12 in 

each mesohabitat type sampled, reaching as high as 4,333 fish 

per 100 m2 in a run at Rio Salado. As in winter 2011–12, the 

highest mean CPUE during summer 2012 was in isolated 

pools (233 fish per 100 m2), whereas the lowest was in flats 

(29.6 fish per 100 m2). Overall mean CPUE per mesohabitat 

across all mesohabitat types was 29.1 fish per 100 m2 during 

winter 2011–12 compared to 85.3 fish per 100 m2 during 

summer 2012. In other words, almost three times as many fish, 

on average, were collected per unit sampling effort during 

summer 2012 compared to winter 2011–12.

Four species of minnows (red shiner, Rio Grande 

silvery minnow, Pimephales promelas [fathead minnow], and 

Platygobio gracilis [flathead chub]) were selected to compare 

preferred mesohabitat characteristics because all are smallbodied minnows and because more than 200 individuals of 

each these species were collected. Red shiner were collected 

across the largest range of depths in both winter 2011–12 

(0.02–4.31 feet [ft]) and summer 2012 (0.05–3.4 ft), as well as 

the largest range of velocities (0.0–4.31 feet per second [ft/s]) 

during winter 2011–12 among the four minnow species of 

interest. Rio Grande silvery minnow occurred in the narrowest 

range of depths (0.30–2.1 ft) during summer 2012, as well as 

the narrowest range of velocities in both winter 2011–12 (0.0–

3.18 ft/s) and summer 2012 (0.02–1.51 ft/s). Median dissolved 

oxygen concentrations for the four minnow species of interest 

exhibited a general upward pattern in a downstream direction 

from the Angostura reach to the San Acacia reach, which is 

most likely the result of the comparatively large number of 

shallow, low-velocity mesohabitats including margin pools 

and isolated pools in the San Acacia reach that contained a 

large amount of algae when the sites were sampled in summer 

2012. Although the ranges of dissolved oxygen concentrations 

associated with the collection of red shiner and Rio Grande 

silvery minnow were quite different because red shiners were 

more widespread, median dissolved oxygen concentrations 

were similar (particularly in the Isleta and San Acacia reaches) 

for both species on a reach basis.

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Appendixes 1–4 73

Appendixes 1–4
74 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012
Appendix 1. Study sites from previous investigations in the Middle Rio Grande, New Mexico 2005–8 (Middle Rio Grande Bosque Initiative reach namWildlife Service, 2014).[MRGBI, Middle Rio Grande Bosque Initiative; USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; --, no data were collected during indicated time period(depth and velocity) were made; HM, hydraulic measurements (depth and velocity) were made in conjunction with mesohabitat features; IFIM, systematic hydraulic measuremecalibrated to flow]

MRGBI 

reach 

names

USGS station 

number USGS station name Short name Map identifier (fig. 2) River mile1

Previous 

Remshardt 

and 

Tashjian 

(2003)

Buntjer 

and 

Remshard

(2005)

Abiquiu -- Rio Chama downstream from Abiquiu Dam Abiquiu ABQ 271.6 + 29.6 -- -- Abiquiu -- Rio Chama upstream from Highway 285 bridge Medanales MDN 271.6 + 5.3 -- H Abiquiu -- Rio Chama upstream from Highway 233 bridge Hernandez HRN 271.6 + 3.3 -- H Embudo -- Rio Grande upstream from Española Alcalde ALC 280.6 -- H Española -- Rio Grande at Española Española ESP 269.0 -- H Otowi -- Rio Grande in White Rock Canyon Buckman Wash BCW 254.0 -- H Cochiti 353330106213500 Rio Grande near Peña Blanca, N. Mex. Peña Blanca PNB 227.5 -- -- Angostura 351848106333400 Rio Grande downstream from Highway 550 at 

Bernalillo, N. Mex.

Bernalillo BRN 203.6 -- -- 

Angostura 350859106402600 Rio Grande upstream from Montano Road northwest at 

Albuquerque, N. Mex.

La Orilla LOR 189.0 HM -- 

Angostura 350432106400500 Rio Grande upstream from Highway 314 at 

Albuquerque, N. Mex.

Barelas BAR 183.0 HM -- 

Angostura 345732106410800 Rio Grande upstream from Interstate Highway 25 near 

Los Padillas, N. Mex.

Los Padillas PAD 173.0 HM -- 

Isleta 344852106424200 Rio Grande upstream from Highway 6 at Los Lunas, 

N. Mex.

Los Lunas I LL1 162.5 HM -- 

Isleta 342644106481300 Rio Grande upstream from Highway 60 near Contreras, 

N. Mex.

Abeytas ABY 133.0 HM -- 

Isleta -- Rio Grande downstream from Highway 60 Bridge Bernardo BRD 130.4 -- -- Isleta -- Rio Grande downstream from San Juan Drain and Rio 

Puerco

Rio Puerco RPC 126.0 -- -- 

Isleta 341842106511100 Rio Grande near La Joya, N. Mex. La Joya LJY 122.0 HM -- Isleta 341542106520700 Rio Grande downstream from Arroyo Rosa de Castillo, 

San Acacia, N. Mex.

Rio Salado RSL 117.5 -- -- 

San Acacia 341044106530300 Rio Grande near Lemitar, N. Mex. Lemitar LEM 109.0 HM -- San Acacia 340215106515500 Rio Grande downstream from Arroyo del Tajo near 

Socorro, N. Mex.

Arroyo del Tajo ATJ 97.0 HM -- 

San Acacia 335403106505800 Rio Grande downstream from Highway 380 near San 

Antonio, N. Mex.

San Pedro SPD 86.5 HM -- 

San Acacia 335229106505800 Rio Grande north of Bosque del Apache, San Antonio, 

N. Mex.

Bosque del 

Apache I

BA1 84.5 HM -- 

San Acacia -- Rio Grande below San Marcial Railroad Bridge San Marcial SNM 68.6 -- -- 

1Confluence of Rio Grande and Rio Chama is at river mile 271.6; number of miles following “+” correspond to the distance upstream from the confluence along the Rio Cham
76 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

EXPLANATION

Site sampled as part of previous investigation

 (2005–8) and map identifier (app. 1)

Middle Rio Grande Bosque Initiative (MRGBI)

 reaches sampled as part of previous

 investigations (2005–8; app. 1) 

 Abiquiu reach

 Angostura reach

 Cochiti reach

 Embudo reach

 Española reach

 Otowi reach

 Isleta reach

 San Acacia reach

Map identifiers followed by short 

names for sampling sites (app. 1)

PNB - Peña Blanca

BRN - Bernalillo

LOR - La Orilla

BAR - Barelas

PAD - Los Padillas

LL1 - Los Lunas I

BRD - Bernardo

ABY - Abeytas

LJY - La Joya

RSL - Rio Salado

LEM - Lemitar

ATJ - Arroyo del Tajo

SPD - San Pedro

BA1 - Bosque del Apache I

ABQ - Abiquiu

MDN - Medanales

HRN - Hernandez

ALC - Alcalde

ESP - Española

BCW - Buckman Wash

RPC - Rio Puerco

SNM - San Marcial

Lower San Juan Riverside Drain

PNB

0 20 40 MILES

0 20 40 KILOMETERS

Base modified from U.S. Geological Survey

1:1,000,000-scale digital data

Transverse Mercator Zone 13 projection

North American Datum of 1983 

NEW MEXICO

Study area

UV96

VU55

UV549

UV6

UV107

*-40

-*25

£¤550

£¤66

£¤285

£¤285

£¤380

£¤60

£¤550

£¤64

*-25

107°30'

107°00' 106°30' 106°00'

36°30'

35°30'

35°00'

34°30'

34°00'

33°30'

36°00'

Cochiti reach

Angostura reach

San Acacia reach

Abiquiu reach

Espanola reach

Embudo reach

Otowi reach

Isleta reach

laf15-CSSJ00-0678_app 02

ABQ

MDN

HRN

ALC

BCW

BRD

RPC

SNM

ESP

LL1

BRN

SPD

LEM

LJY

ATJ

PAD

ABY

RSL

PNB

BA1

LOR

BAR

Jemez Ri ver

Rio Pu e rco

Al amosa C reek

Arroyo Comanche

Rio Galli n a

Jemez River

Rio Salado

Rio Cham a

El Rito

Galiste o Cre ek

Rio Tusas

Santa Fe Ri v er

Elephant Butte

Reservoir

Rio

Grande

JEMEZ

CANYON

DAM ANGOSTURA

DIVERSION

DAM

COCHITI

DAM

ISLETA

DIVERSION

DAM

SAN ACACIA

DIVERSION

DAM

SANDOVAL

COUNTY

BERNALILLO

COUNTY

VALENCIA

COUNTY

SOCORRO

COUNTY

RIO ARRIBA

COUNTY

SANTA FE

COUNTY

LOS ALAMOS

COUNTY

BOSQUE DEL APACHE

NATIONAL WILDLIFE REFUGE 

SAN ALAMEDA BRIDGE

Alameda

Bosque Farms

Escondida

Los Padillas

La Joya

Arroyo del Tajo

Lower San Juan

Riverside Drain

San Acacia

San Antonio

Lemitar

Santa Fe

Bernalillo

Los Alamos

Tierra Amarilla

Los Lunas

Socorro

Albuquerque

Appendix 2. Map of sites from previous investigations in the Middle Rio Grande, New Mexico, 2005–8.
Appendixes 1–4 77

Appendix 3. Data tables and definitions of data elements associated with the project geodatabase.

tbl_discharge – Discharge data

Field code Field name Definition Codes (if applicable)

site_nm Site name Long site name for sampling 

location

Rio Salado

Arroyo del Tajo

La Joya

Abeytas

Lemitar

San Pedro

La Orilla

Los Padillas

Barelas

Los Lunas 2

Los Lunas 1

Bernalillo

Peña Blanca

Bosque del Apache 2

Bosque del Apache 1

date_va Date value Discharge measurement date

time_va Time value Discharge measurement time

discharge_cfs_va Discharge value Discharge value in cubic feet per 

second

tbl_fish – Fish assemblage data

date_va Date value Fish collection date

site_nm Site name Long site name for sampling 

location

Rio Salado

Arroyo del Tajo

La Joya

Abeytas

Lemitar

San Pedro

La Orilla

Los Padillas

Barelas

Los Lunas 2

Los Lunas 1

Bernalillo

Peña Blanca

Bosque del Apache 2

Bosque del Apache 1

site_abv Site abbreviation Site abbreviation for sampling 

location

RSL – Rio Salado

ATJ – Arroyo del Tajo

LJY – La Joya

ABY – Abeytas

LEM – Lemitar

SPD – San Pedro

LOR – La Orilla

PAD – Los Padillas

BAR – Barelas

LL2 – Los Lunas 2

LL1 – Los Lunas 1

BRN – Bernalillo

PNB – Peña Blanca

BA2 – Bosque del Apache 2

BA1 – Bosque del Apache 1
78 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

tbl_fish – Fish assemblage data—Continued

date_va Date value Fish collection date

sample_id Sample identifier Sampling event identifier

1 – November or December 2011

2 – June or August 2012

3 – February 2012

mesohab_id Mesohabitat identifier Mesohabitat identifier

mesohab_com Mesohabitat comments Mesohabitat comments

unique_id Unique identifier

Unique identifier composed 

of site_abv+sample_

id+mesohab_id

HYBAMA Hybognathus amarus Fish count for species

HYBAMA_SL Hybognathus amarus standard 

length

Standard length(s) for Rio 

Grande silvery minnow(s)

CYPCAR Cyprinus carpio Fish count for species

CYPLUT Cyprinella lutrensis Fish count for species

CARCAR Carpiodes carpio Fish count for species

RHICAT Rhinichthys cataractae Fish count for species

CYCELO Cycleptus elongatus Fish count for species

CATCOM Catostomus commersonii Fish count for species

AMEMEL Ameiurus melas Fish count for species

ICTPUN Ictalurus punctatus Fish count for species

PYLOLI Pylodictis olivaris Fish count for species

PLAGRA Platygobio gracilis Fish count for species

AMENAT Ameiurus natalis Fish count for species

GAMAFF Gambusia affinis Fish count for species

DORCEP Dorosoma cepedianum Fish count for species

LEPCYA Lepomis cyanellus Fish count for species

POMANN Pomoxis annularis Fish count for species

PIMPRO Pimephales promelas Fish count for species

MORCHR Morone chrysops Fish count for species

MICSAL Micropterus salmoides Fish count for species

LEPMAC Lepomis macrochirus Fish count for species

Unknown Unknown species Fish count for unknown species

Total_fish Total fish Total number of fish collected 
Appendixes 1–4 79

tbl_fish_habitat – Fish habitat data

Field code Field name Definition Codes (if applicable)

date_va Date value Fish collection date

site_nm Site name Long site name for sampling location

Rio Salado

Arroyo del Tajo

La Joya

Abeytas

Lemitar

San Pedro

La Orilla

Los Padillas

Barelas

Los Lunas 2

Los Lunas 1

Bernalillo

Peña Blanca

Bosque del Apache 2

Bosque del Apache 1

site_abv Site abbreviation Site abbreviation for sampling location

RSL – Rio Salado

ATJ – Arroyo del Tajo

LJY – La Joya

ABY – Abeytas

LEM – Lemitar

SPD – San Pedro

LOR – La Orilla

PAD – Los Padillas

BAR – Barelas

LL2 – Los Lunas 2

LL1 – Los Lunas 1

BRN – Bernalillo

PNB – Peña Blanca

BA2 – Bosque del Apache 2

BA1 – Bosque del Apache 1

sample_id Sample identifier Sampling event identifier

1 – November or December 2011

2 – June or August 2012

3 – February 2012

mesohab_id Mesohabitat identifier Mesohabitat identifier

mesohab_com Mesohabitat comments Mesohabitat comments

unique_id Unique identifier Unique identifier composed of site_abv+sample_

id+mesohab_id

mesohab_cl Mesohabitat class Mesohabitat class as defined by the mapping crew in 

situ

1 – pool

3 – riffle

7 – backwater

8 – isolated pool

10 – run 

13 – flat

14 – embayment

15 – forewater

mesohabitat_cd Mesohabitat code Mesohabitat class as defined by the fish crew

lat_va Latitude Latitude in decimal degrees

lon_va Longitude Longitude in decimal degrees

seine_lg Seine length Length of seine haul, in meters

depth_va Depth value Water depth, in feet

velocity_va Velocity 1 Water velocity, in feet per second

velocity2_va Velocity 2 Water velocity, in feet per second

temp_C Temperature Temperature, in degrees Celsius

cond_μS Specific conductance Specific conductance, in microsiemens per centimeter

DO_mL Dissolved oxygen Dissolved oxygen concentration, in milligrams per liter

pH pH pH value measured using the pH scale

comments Comments Comments
80 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

tbl_fish_cover – Fish cover data

Field code Field name Definition Codes (if applicable)

unique_id Unique identifier Unique identifier composed of site_abv 

+sample_id + mesohab_id

transect_id Transect identifier Transect identifier for each mesohabitat 

sampled (1–5 transects per unit)

dom_sub_cd Dominant substrate code Dominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NA – not applicable

NR – not recorded

SA – sand

sub_dom_sub_cd Subdominant substrate code Subdominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NA – not applicable

NR – not recorded

SA – sand

SB – small boulder

fil_algae_pc Filamentous algae Presence of filamentous algae along transect, in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NA – Not applicable

NR – Not recorded

macrophytes_pc Macrophytes Presence of macrophytes along transect, 

in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NA – Not applicable

NR – Not recorded

woody_deb_pc Woody debris Presence of woody debris (<0.3 meters in 

diameter) along transect, in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NR – Not recorded

lg_woody_deb_pc Large woody debris

Presence of large woody debris (>0.3 

meters in diameter) along transect, in 

percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NR – Not recorded

overhang_veg Overhanging vegetation Presence of overhanging vegetation along 

transect, in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NA – Not applicable

NR – Not recorded
Appendixes 1–4 81

tbl_fish_cover – Fish cover data—Continued

Field code Field name Definition Codes (if applicable)

undercut_bnk Undercut bank Presence of undercut bank along transect, 

in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NA – Not applicable

NR – Not recorded

art_struct Artificial structures Presence of artificial structures along 

transect, in percent

0 – absent (0 percent)

1 – sparse (1–10 percent)

2 – moderate (11–40 percent)

3 – heavy (41–75 percent)

4 – very heavy (>75 percent)

NR – Not recorded

comments Comments Comments

tbl_margin – Margin habitat data

Field code Field name Definition Codes (if applicable)

unique_id Unique identifier Unique identifier composed of site_abv +sample_

id + mesohab_id

transect_id Transect identifier (margin) Transect identifier for each margin mesohabitat 

sampled (1–5 transects per unit)

lmargin_w_m Left margin width Left margin width, in meters NA – not applicable

NR – not recorded

lmargin_d_m Left margin depth Left margin depth, in meters

E – estimate

< – less than

> – greater than

NA – not applicable

NR – not recorded

lmargin_v_fts Left margin velocity Left margin velocity, in feet per second

E – estimate

< – less than

NA – not applicable

NR – not recorded

lmargin_subs Left margin substrate type Left margin dominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NA – not applicable

NR – not recorded

SA – sand

lmargin_subs_per_cov Left margin substrate percent 

cover

Left margin dominant substrate coverage, in 

percent

NA – not applicable

NR – not recorded

lmargin_subs_sz Left margin substrate size Left margin substrate size, in millimeters NA – not applicable

NR – not recorded

lembed_pct Left margin embeddedness Left margin substrate embeddedness, in percent NA – not applicable

NR – not recorded
82 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

tbl_margin – Margin habitat data—Continued

Field code Field name Definition Codes (if applicable)

lmargin_subdom Left margin subdominant substrate type Left margin subdominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

NA – not applicable

NR – not recorded

SA – sand

lmargin_subdom_per_

cov

Left margin subdominant substrate percent coverLeft margin subdominant substrate coverage, in 

percent

NA – not applicable

NR – not recorded

lmargin_subdom_sz Left margin subdominant substrate size

Left margin subdominant substrate size, in millimeters

NA – not applicable

NR – not recorded

lmargin_peri_pct Left margin periphyton Left margin periphyton cover, in percent NA – not applicable

NR – not recorded

lmargin_densi Left margin densiometer Left margin densiometer measurement (0–17) NA – not applicable

NR – not recorded

lbank_angle First left margin bank angle First left margin bank angle, in degrees NA – not applicable

NR – not recorded

lbank2_angle Second left margin bank angle Second left margin bank angle, in degrees NA – not applicable

NR – not recorded

lbank3_angle Third left margin bank angle Third left margin bank angle, in degrees NA – not applicable

NR – not recorded

lbank4_angle Fourth left margin bank angle Fourth left margin bank angle, in degrees NA – not applicable

NR – not recorded

lbank5_angle Fifth left margin bank angle Fifth left margin bank angle, in degrees NA – not applicable

NR – not recorded

rmargin_w_ft Right margin width Right margin width, in feet

< – less than

NA – not applicable

NR – not recorded

rmargin_d_ft Right margin depth Right margin depth, in feet

< – less than

> – greater than

E – estimate

NA – not applicable

NR – not recorded

rmargin_v_ft Right margin velocity Right margin velocity, in feet per second

> – greater than

< – less than

≤ – less than or equal to

E – estimate

NA – not applicable

NR – not recorded

rmargin_subs Right margin substrate type Right margin dominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NA – not applicable

NR – not recorded

SA – sand
Appendixes 1–4 83

tbl_margin – Margin habitat data—Continued

Field code Field name Definition Codes (if applicable)

rmargin_subs_per_cov Right margin substrate percent 

cover

Right margin dominant substrate coverage, in 

percent

E – estimate

NA – not applicable

NR – not recorded

rmargin_subs_sz Right margin substrate size Right margin substrate size, in millimeters NA – not applicable

NR – not recorded

rembed_pct Right margin embeddedness Right margin substrate embeddedness, in percent

E – estimate

NA – not applicable

NR – not recorded

rmargin_subdom Right margin subdominant 

substrate type Right margin subdominant substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NA – not applicable

NR – not recorded

SA – sand

rmargin_subdom_per_

cov

Right margin subdominant 

substrate percent cover

Right margin subdominant substrate coverage, in 

percent

E – estimate

NA – not applicable

NR – not recorded

rmargin_subdom_sz Right margin subdominant 

substrate type

Right margin subdominant substrate size, in millimeters

NA – not applicable

NR – not recorded

rmargin_peri_pct Right margin periphyton Right margin periphyton cover, in percent

E – estimate

NA – not applicable

NR – not recorded

rmargin_densi Right margin densiometer 

reading Right margin densiometer measurement (0–17)

E – estimate

NA – not applicable

NR – not recorded

rbank_angle First right margin bank angle First right margin bank angle, in degrees

E – estimate

NA – not applicable

NR – not recorded

rbank2_angle Second right margin bank angle Second right margin bank angle, in degrees

E – estimate

NA – not applicable

NR – not recorded

rbank3_angle Third right margin bank angle Third right margin bank angle, in degrees NA – not applicable

NR – not recorded

rbank4_angle Fourth right margin bank angle Fourth right margin bank angle, in degrees NA – not applicable

NR – not recorded

comments Comments Comments
84 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

tbl_physical – Physical data

Field code Field name Definition Codes (if applicable)

unique_id Unique identifier Unique identifier composed of site_abv 

+sample_id + mesohab_id

transect_id Transect identifier (mesohabitat) Transect identifier for each mesohabitat 

sampled (1–5 transects per unit) NR – not recorded

transect_w_m Transect width Transect width, in meters E – estimate

NR – not recorded

depth_ft Depth Depth, in feet E – estimate

NR – not recorded

velocity1 First velocity First velocity, in feet per second (may 

include multiple measurements)

E – estimate

NR – not recorded

velocity2 Second velocity

Second velocity (if necessary), in feet 

per second (may include multiple 

measurements)

E – estimate

velocity(final) Final velocity

Final velocity, in feet per second 

(average of velocity measurements if 

multiple measurements were made)

E – estimate

NR – not recorded

subs_cd Substrate type Substrate type

CB – cobble

FN – fines

GC – gravel coarse

GF – gravel fine

HP – hardpan

NR – not recorded

SA – sand

subs_size Substrate size Substrate size, in millimeters NA – not applicable

NR – not recorded

embed_pct Embeddedness Substrate embeddedness, in percent NR – not recorded

tbl_water_quality – Water-quality data

Field code Field name Definition Codes (if applicable)

unique_id Unique identifier Unique identifier composed of site_abv 

+sample_id + mesohab_id

transect_id Transect identifier (mesohabitat) Transect identifier for each mesohabitat 

sampled (1–5 transects per unit)

cond_μS Specific conductance measurement

Specific conductance, in microsiemens per 

centimeter NR – not recorded

temp_C Temperature Temperature, in degrees Celsius

DO_mL Dissolved oxygen measurement 2 Dissolved oxygen, in milligrams per liter

pH pH measurement pH value measured by using the pH scale
Appendixes 1–4 85

Appendix 4. Federal Geographic Data Committee-compliant metadata record.

Identification_Information

 Citation: mesohab_11092011

 Citation_Information:

 Originator: U.S. Geological Survey

 Publication_Date: 20141215

 Title: Physical Characteristics and Fish Assemblage Composition at the Site- and Mesohabitat-Scale over a Range of Streamflows in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012.

Geospatial_Data_Presentation_Form: vector digital data

Description:

Abstract: In winter 2011–12 and summer 2012, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps 

of Engineers, Albuquerque District and the U.S. Fish and Wildlife Service New Mexico Fish and Wildlife Conservation Office 

in Albuquerque, New Mexico, evaluated the physical characteristics and fish assemblage composition of available mesohabitats 

over a range of streamflows at fifteen sites on the middle Rio Grande in New Mexico. Data were collected at all 15 sites during 

winter 2011–12 (moderate streamflow) and a subset, the 13 most downstream sites, in summer 2012 (low streamflow). Sites 

were grouped into four river reaches separated by diversion dams listed in downstream order (names of the diversion dames 

are followed by short names in parentheses of the sites nearest each dam, listed in downstream order): Cochiti (Peña Blanca), 

Angostura (Bernalillo, La Orilla, Barelas, Los Padillas), Isleta (Los Lunas I, Los Lunas II, Abeytas, La Joya, Rio Salado), and 

San Acacia (Lemitar, Arroyo del Tajo, San Pedro, Bosque del Apache I, and Bosque del Apache II). Stream habitat was mapped 

in the field by using a geographic information system in conjunction with a Global Positioning System. Fish assemblage was 

determined during both streamflow regimes, and fish were collected by seining in each mesohabitat where physical characteristic data (depth, velocity, dominant substrate type and size, and percent embeddedness) and water-quality properties (temperature, 

dissolved oxygen, specific conductance, and pH; during summer 2012 only) were measured.

Time_Period_of_Content:

 Time_Period_Information:

 Single_Date/Time:

 Calendar_Date: 2011

 Currentness_Reference: 2011

 Status:

 Progress: Complete

 Maintenance_and_Update_Frequency: None Planned

 Spatial_Domain:

 Bounding_Coordinate:

 West_Bounding_Coordinate: -107.097605

 East_Bounding_Coordinate: -106.131221

 North_Bounding_Coordinate: 35.568157

 South_Bounding_Coordinate: 33.809107

 Keywords:

 Theme:

 Theme_Keyword: Rio Grande silvery minnow

 Theme_Keyword: biology

 Theme_Keyword: surface water

 Theme_Keyword: water quality
86 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

 Theme_Keyword: mesohabitats

 Place:

 Place_Keyword: Middle Rio Grande

 Place_Keyword: New Mexico

 Place_Keyword: Albuquerque

 Place_Keyword: Sandoval County

 Place_Keyword: Bernalillo County

 Place_Keyword: Valencia County

 Place_Keyword: Socorro County 

Use_Constraints: These data are for informational purposes only. These data have not received Bureau approval and as such are 

provisional and subject to revision. The data are released on the condition that neither the U.S. Geological Survey, its cooperators, nor the U.S. Government may be held liable for any damages resulting from its authorized or unauthorized use. Although 

these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or 

implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall 

the act of distribution constitute any such warranty. 

 Native_Data_Set_Environment: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.2.1.3497

Data_Quality_Information:

 Lineage:

 Process_Step:

 Process_Description: Geographic data were collected by using Trimble DSM 232 GPS receiver. GPS data were translated 

and captured in ArcGIS. The data were postprocessed and stored in a geodatabase as polygon features representing each of the 

mapped mesohabitat units. Additional data collected (fish assemblage, physical characteristics and water-quality information) 

were stored in attribute tables within the geodatabase and link to the geographic information via relationship class.

 Process_Date: 20141124

Spatial_Data_Organization_Information:

 Direct_Spatial_Reference_Method: Vector

 Point_and_Vector_Object_Information:

 SDTS_Terms_Description:

 SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains

 Point_and_Vector_Object_Count: 809

Spatial_Reference_Information:

 Horizontal_Coordinate_System_Definition:

 Planar:

 Map_Projection_Name: Albers Equal-Area Conic USGS CONUS NAD83

 Albers:

 Standard_Parallel: 29.5

 Standard_Parallel: 45.5

 Longitude_of_Central_Meridian: -96.0

 Latitude_of_Projection_Origin: 23.0

 False_Easting: 0.0

 False_Northing: 0.0

 Planar_Coordinate_Information:
Appendixes 1–4 87

 Planar_Coordinate_Encoding_Method: coordinate pair

 Coordinate_Representation:

 Abcissa_Resolution: 0.0001

 Ordinate_Resolution: 0.0001

 Planar_Distance_Units: meters

 Geodetic_Model:

 Horizontal_Datum_Name: North American Datum of 1983

 Ellipsoid_Name: Geodetic Reference System 80

 Semi-major_Axis: 6378137.000000

 Denominator_of_Flattening_Ratio: 298.257222

Entity_and_Attribute_Information:

 Detailed_Description:

 Entity_Type:

 Entity_Type_Label: mesohab_11092011

Attribute:

 Attribute_Label: OBJECTID

 Attribute_Definition: Internal feature number.

 Attribute_Definition_Source: ESRI

 Attribute_Domain_Values:

 Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated.

 Attribute:

 Attribute_Label: SHAPE

 Attribute_Definition: Feature geometry.

 Attribute_Definition_Source: ESRI

 Attribute_Domain_Values:

 Unrepresentable_Domain: Coordinates defining the features.

Attribute:

 Attribute_Label: site_abv

 Attribute_Definition: Site abbreviation.

 Attribute:

 Attribute_Label: sample_id

 Attribute_Definition: Sample event ID.

 Attribute:

 Attribute_Label: unique_id

 Attribute_Definition: Unique mesohabitat identifier. Combination of site_abv, sample_id and

 mesohab_id

 Attribute:

 Attribute_Label: mesohab_id

 Attribute_Definition: Mesohabitat identifier.

 Attribute:
88 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

 Attribute_Label: mesohab_cl

 Attribute_Definition: Mesohabitat type.

Attribute:

 Attribute_Label: X

 Attribute_Definition: Longitude in decimal degrees.

Attribute:

 Attribute_Label: Y

 Attribute_Definition: Latitude in decimal degrees.

Attribute:

 Attribute_Label: mesohab_lg

 Attribute_Definition: Approximate midchannel length of mesohabitat (meters)

Attribute:

 Attribute_Label: Shape_Length

 Attribute_Definition: Perimeter of feature in meters.

 Attribute_Domain_Values:

 Unrepresentable_Domain: Positive real numbers that are automatically generated.

Attribute:

 Attribute_Label: Shape_Area

 Attribute_Definition: Area of feature in meters squared.

 Attribute_Domain_Values:

 Unrepresentable_Domain: Positive real numbers that are automatically generated.

Distribution_Information:

 Resource_Description: Downloadable Data

Metadata_Reference_Information:

 Metadata_Date: 20141124

 Metadata_Contact:

 Contact_Information:

 Contact_Organization_Primary:

 Contact_Organization: U.S. Geological Survey

 Contact_Person: Public Information Officer

 Contact_Address:

 Address_Type: mailing and physical address

 Address: 1505 Ferguson Lane

 City: Austin

 State_or_Province: Texas

 Postal_Code: 78754

 Country: USA

 Contact_Voice_Telephone: 512–927–3500

 Contact_Facsimile_Telephone: 512–927–3590

 Contact_Electronic_Mail_Address: gs-w-txpublic-info@usgs.gov
Appendixes 1–4 89

 Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

 Metadata_Standard_Version: FGDC–STD–001–1998

 Metadata_Time_Convention: local time

 Metadata_Extensions:

 Online_Linkage: http://www.esri.com/metadata/esriprof80.html

 Profile_Name: ESRI Metadata Profile
90 Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012

Publishing support provided by

Lafayette Publishing Service Center

Information regarding water resources in Texas is available at 

http://tx.usgs.gov/
Braun and others—Physical Characteristics and Fish Assemblage Composition in the Middle Rio Grande, New Mexico, Winter 2011–12, Summer 2012—SIR 2015–5025

ISBN 978-1-4113-3919-4

9 7 81411 3391 9 4

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20155025