Sy camore C reek

West Clear Creek

Sedona

Cornville

Williams

Paulden

Prescott

Clarkdale

Flagstaff

Camp Verde

Chino Valley Cottonwood

09505800

09504420

09504500

09504000 09503700

OakCreek

Dry Beaver Creek

Wet Bea ver Creek

Verde River

112° 111°30'

Big Chino Wash

112°30'

34°30'

35°

0 5 10 MILES

0 5 10 KILOMETERS

Base modified from U.S. Geological Survey digital data, 1:100,000, 1982 Universal Transverse Mercator projection, Zone 12

Map area

Study Area

ARIZONA

Central

Highlands

Basin and Range

Lowlands

Upland

Plateau

Pilot study aquatic insect locations

Pilot study fish and aquatic insect locations

EXPLANATION

USGS streamgage location

 09503700:Verde River near Paulden, AZ

 0904000: Verde River near Clarkdale, AZ

 09504420: Oak Creek near Sedona, AZ

 09504500:Oak Creek near Cornville, AZ

 09505800: West Clear Creek near Camp 

 Verde, AZ

Pilot study fish locations

This report summarizes analyses of middle Verde 

River watershed environmental flows detailed in U.S. 

Geological Survey Scientific 

Investigations Report 2017-

5100, “Preliminary synthesis 

and assessment of environmental flows in the middle 

Verde River watershed, Arizona, by N.V. Paretti, A.M.D. 

Brasher, S.L. Pearlstein, D.M. 

Skow, B. Gungle, and B.D. 

Garner. All figures from Paretti 

and others (2018) unless otherwise noted.

Middle Verde River watershed, Arizona, including streamgaging stations, major towns, and tributaries. 

Map modified from Garner and others (2013).

Assessment of Environmental Flows in the Middle Verde River 

Watershed, Arizona

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2018-3062

October 2018

The Verde River is among the largest 

streams in Arizona. Its watershed covers 4.2 million acres in central Arizona, 

includes about 500 miles of perennial 

streams, and provides 40 percent of the 

surface water delivered to the Phoenix 

metropolitan area by the Salt River Project 

(The Nature Conservancy, 2009). The 

Verde River watershed is home to a 

number of native fish and special status 

species. 

The flows that occur in the middle Verde 

River watershed are largely unregulated 

and are less affected by urban use, urban 

and agricultural runoff, and channelization 

than in the lower Verde River watershed.

Introduction
The first step in determining 

Verde River environmental flows was 

to develop estimates of flow regimes 

that sustain properly functioning 

ecosystems. The natural hydrologic 

regime of a river or stream can be 

divided into four components—

floods, high-flow pulses, base flows, 

and extreme low flows. To represent 

these components of the natural flow 

regime, measures of magnitude, timing, duration, frequency, and rate of 

change of streamflow must be developed (Poff and others, 1997).

Southwestern desert streams, 

including the Verde River, are characterized by large variations in flow 

magnitude. However, flow in the 

Verde River and its tributaries is frequently composed entirely of groundwater discharging to the stream 

channel. Such base-flow regimes are 

highly dependent on groundwater/

surface-water interactions. Climate Factors : Precipitation

 Temperature

Flow Regime : Magnitude 

 Frequency 

 Duration

 Timing 

 Rate of Change

Ecological Response : Algae

 Aquatic Insects

 Fish

 Riparian Vegetation

EXPLANATION

Hydrograph for U.S. Geological Survey stream gage Verde River near Clarkdale, AZ (09504000), 

water year 2005, demonstrating flow-regime components. AZ, Arizona. Modified from Poff and 

others (1997) and Bunn and Arthington (2002).

High to medium 

magnitude, infrequent, 

short duration, 

seasonally unpredictable, high variability

Moderate habitat 

disturbance, insect drift, 

and fish dispersal, fine 

sediments removed, 

distribution of food 

supplies

Fall flooding 

(tropical moisture and [or] 

low pressure systems

Low magnitude, 

frequency, seasonally 

predictable, low 

variability

Base flow 

(groundwater)

Spring flooding 

(Snowmelt)

No habitat disturbance 

reproductive triggers for 

aquatic insects and fish,

 seed establishment

 High magnitude, 

frequency, long 

duration,

 seasonally 

unpredictable, 

 high variability

Major habitat

 disturbance, stream 

connectivity, and floodplain inundation, channel modification, sediment 

and nutrient influx and 

redistribution, and biological 

community shift

Winter flooding

 (low pressure systems)

Medium 

magnitude, 

frequent flood 

pulses, seasonally 

predictable, 

high variablity 

Minor habitat disturbance, 

streambed scour, sediment 

transport, nutrient redistribution, fish dispersal and 

insect drift

Summer flooding 

(thunderstorms)

10/01/2004 12/01/2004 02/01/2005 04/01/2005 06/01/2005 08/01/2005 10/01/2005

100

1,000

 10,000

 100,000 Discharge, in cubic feet per second

 1,000,000

The magnitude, frequency, duration, timing, and rate 

of change of hydrologic conditions can be used to characterize the entire range of stream flows, from low flows to 

floods, that are critical to the integrity of river ecosystems 

(Poff and others, 1997). Environmental flows describe the 

hydrologic conditions necessary to sustain properly functioning aquatic ecosystems which in turn support human 

livelihoods and well-being (Arthington and others, 2018). 

Streams altered by human modifications, such as dams, 

diversions, or channel engineering, can still be managed to 

mimic an environmental flow regime that meets ecological and social objectives (Acreman and others, 2014). To 

understand the consequences of various water-use scenarios to Arizona’s middle Verde River watershed ecosystem, 

the U.S. Geological Survey set out to first understand the 

system’s environmental flows. The purpose of Paretti and 

others (2018) was to compile existing hydrological and 

ecological data to better understand environmental flows in 

the setting of the middle Verde River watershed. 

Ecosystem water needs include use by riparian vegetation and the habitat requirements of fish and macroinvertebrates (aquatic insects). The hydrologic characteristics 

that affect ecosystem water needs include both streamflow 

(that is, the magnitude, frequency, timing, and variability of flow) and groundwater conditions such as depth to 

groundwater and annual fluctuations of groundwater levels 

(Poff and others, 2010; Konrad and others, 2008).

Surface Water and 

Groundwater

The Verde River north of Clarkdale, Arizona. River flow is toward the viewer. U.S. 

Geological Survey streamgage 09504000 stilling well and cable way are located on 

the bank. Photograph by A.M.D. Brasher, U.S. Geological Survey.
Geomorphic river habitats (pool, run, and riffle) distribution per river mile in 

the lower-middle Verde River watershed reach of the Verde River, Arizona. 

70,000

60,000

50,000

40,000

30,000

20,000

10,000

0

109 

111

113

115

117

119

121

123

125 

127 

129

131

133

135

137

139

141

143

Area, in square meters

Verde River mile, Oak Creek (109) up to Sycamore Creek (143)

Water depth and velocity, which are 

controlled by channel geomorphology (the 

shape and material of the riverbed), result 

in stream habitat features such as pools, 

riffles, and runs. The most diverse fish and 

macroinvertebrate assemblages are found in 

streams that have more complex riffle, run, 

and pool habitat, with large wood, boulders, 

undercut banks, and tree roots. Human use 

of stream areas often results in the destruction of this habitat caused by increased 

sedimentation and (or) reduction in flow. 

This leads to negative impacts on biological 

health through a reduction in species diversity and abundance. Pool, riffle, and run 

features were quantified for separate reaches 

of the Verde River from aerial imagery. The 

upper-middle and lower-middle reaches of 

the Verde River in the middle Verde River 

watershed are similarly complex geomorphologically, although the upper-middle 

reach had more riffle habitat and less pool 

habitat than the lower-middle reach.

Geomorphology

A pool, run, and riffle on the Verde River. Photograph by 

N.V. Paretti, U.S. Geological Survey. 
Percentage of vegetation 

classes distributed along 

the A, upper-middle Verde 

River watershed reach 

of the Verde River, Ariz. 

(river miles 144–191), and 

B, lower-middle Verde 

River watershed reach of 

the Verde River, Ariz. (river 

miles 109–143). 

The Verde River watershed contains 

some of the most extensive acreage of 

Fremont cottonwood-Goodding willow 

forest and mixed broadleaf riparian forest 

in Arizona and is home to the threatened 

yellow-billed cuckoo and the endangered 

southwestern willow flycatcher (Stevens 

and others, 2008). Because of the relatively 

unregulated flow of the Verde River, riparian vegetation along the banks varies in age, 

which is instrumental in maintaining forest 

resiliency. 

An analysis of aerial imagery showed 

that the upper-middle Verde River watershed has more upland plant species, such as 

junipers, and fewer lowland species, such 

as cottonwoods and mesquites, compared 

to their abundance in the lower-middle 

sections. Differences in vegetation within 

the upper-middle and lower-middle reaches 

appear to be related more to differences 

in climate and hydrology than to human 

alterations. 

Mixed Canopy

29 percent

Mixed Shrub

21 percent

Juniper

34 percent

Mesquite

11 percent

Cottonwood

4 percent

Agriculture

1 percent Emergent Aquatic

Vegetation

<1 percent

Mixed Canopy

48 percent

Mixed Shrub

Juniper 17 percent

1 percent

Cottonwood

10 percent

Agriculture

4 percent

Emergent Aquatic

Vegetation

1 percent

Mesquite

19 percent

A

B

Aquatic insects such as mayflies and 

caddisflies play a crucial role in the food 

web of a stream ecosystem, and their abundance and diversity is an indicator of stream 

health. Because these insects live for a year 

or more and rarely move beyond a given 

river reach, their response to local waterquality conditions is useful in assessing the 

ecological condition of a stream. Several 

aquatic insect community metrics significantly increased or decreased based on flow 

conditions defined by season, magnitude 

of flow, presence of river diversions, and 

stream size (Verde River or tributary).

Aquatic insect samples and habitat 

measurements were collected from six sites 

in the upper-middle Verde River to better understand flow-habitat relations. The 

largest insect diversity was at the Clarkdale 

streamgage site. The Verde River below 

Granite Creek site had slower stream velocity, smaller substrate, and greater riparian 

cover than the other five sites. It also had a 

different insect community than the other 

sites, including the greatest variety of caddisfly types, lowest variety of mayfly types, 

and lowest overall diversity of all locations. Several insect types were observed 

at the Verde River Below Granite Creek 

site that were not found at any of the other 

five locations, likely because of the differences in flow and habitat type. The Paulden 

streamgage site had the greatest range of 

stream velocities of all the sites and a large 

variety of mayfly types, but very low midge 

diversity. The other four stations were similar in overall diversity and caddisfly types, 

and in particular, the Perkinsville Bridge 

and Reitz Ranch samples had similar insect 

community structures.

Riparian Vegetation

Aquatic Insects

View looking northwest of the Verde River north of Reitz Ranch, Arizona. River flow is toward 

the viewer. Photograph by N.V. Paretti, U.S. Geological Survey.

Mixed Canopy

29 percent

Mixed Shrub

21 percent

Juniper

34 percent

Mesquite

11 percent

Cottonwood

4 percent

Agriculture

1 percent Emergent Aquatic

Vegetation

<1 percent

Mixed Canopy

48 percent

Mixed Shrub

Juniper 17 percent

1 percent

Cottonwood

10 percent

Agriculture

4 percent

Emergent Aquatic

Vegetation

1 percent

Mesquite

19 percent

A

B
Percentage of native and nonnative fish by location in 

the middle Verde River watershed, Arizona.

The empirical relations determined in this study can be used to 

develop the basis for a conceptual 

model of environmental flows in the 

middle Verde River watershed. A 

robust conceptual model can provide 

the foundation for developing physically based, quantitative and predictive models of environmental flows 

for the middle Verde River. 

Such models can improve 

the understanding of the effects of 

increased stresses from climate variability and the demands on the water 

supply of the Verde River.

0

10

20

30

40

50

60

70

80

90

100

Verde River

near 

Paulden 

Verde River

near 

Perkinsville

West Clear

Creek Total fish 

collected

at all

locations

Native and nonnative fish, in percent

Native

Nonnative

EXPLANATION

Verde River

 below 

Granite Creek 

Oak Creek

0

25

50

75

100

 Desert Sucker

 Sonora Sucker

 Roundtail Chub

 Longfin Dace

 Speckled Dace

Individual species in percent

Native fish

0

25

50

75

100

 Black Bullhead

 Yellow Bullhead

 Common Carp

 Green Sunfish

 Largemouth Bass

 Smallmouth Bass

 Rock Bass

 Mosquito Fish

 Rainbow Trout

 Red Shiner

Individual species in percent

Nonnative fish

West Clear Creek Oak Creek Verde River near Perkinsville Verde River near Paulden Verde River below Granite 

EXPLANATION

The native fish of the Southwest 

are highly adapted to a range of conditions that include extreme temperatures, 

unpredictable flood flows, and sedimentladen waters (Rinne, 1992; Lytle and 

Poff, 2004); they are also under stress 

from changes in river ecosystems and 

flows. During high flow years, native 

fish species typically increase in numbers and nonnative species decrease in 

numbers (Rinne, 2005; Gido and Propst, 

2012). In the middle Verde River watershed, native fish have been declining 

since the introduction of nonnative fish 

species nearly a century ago; high flows 

are one of the last remaining natural 

defenses native fish have against nonnative fish pressures.

 The abundance and distribution of 

native and nonnative fish were determined at five sites in the middle Verde 

River watershed. Five species were identified as native and 10 were nonnative. 

Longfin and speckled dace were only 

collected at the Perkinsville site, and 

rock bass, black bullhead, and common 

carp were only collected at Oak Creek. 

The percentage of non-native species 

was greater at the Paulden location and 

at the Oak Creek and West Clear Creek 

tributaries. The Verde River Below 

Granite Creek and the Perkinsville sites 

had similar percentages of individual 

native fish, but the Verde River Below 

Granite Creek and the Paulden sites had 

the most similar fish assemblages.

The median stream velocity associated with the native fish species was significantly faster than that associated with 

nonnative fish species and native fish 

used a wider range of velocities than did 

nonnative species. The median stream 

velocity associated with the nonnative 

fish was significantly slower than that of 

the available microhabitat, and velocities 

associated with native fish were faster 

than the median velocity of the available 

microhabitat. Although both native and 

nonnative fish used most water depths, 

nonnative species preferred the shallowest depths whereas native species more 

commonly used depths greater than 

2.3 feet. Both native and nonnative 

species used all sizes of substrate, but 

in general, native fish were significantly 

more likely to use coarser substrates 

(in particular, gravels and cobbles) 

than nonnative fish, and nonnative fish 

preferred smaller diameter substrate than 

native fish.

Desert sucker (native fish). Photograph by N.V. Paretti, U.S. 

Geological Survey.

Bullhead (nonnative fish). Photograph 

by N.V. Paretti, U.S. Geological Survey.

Fish

Future Directions

West of the Verde River near Perkinsville, Arizona. River flow is toward the viewer. Photograph by A.M.D. 

Brasher, U.S. Geological Survey.
ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

https://doi.org/10.3133/fs20183062

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By Bruce Gungle and Nicholas V. Paretti

Edited by Katherine Jacques

Layout by Kimber Petersen