U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2016–5115

Prepared in cooperation with the Arizona Department of Water Resources and Yavapai County

Simulation of Groundwater Withdrawal Scenarios for the 

Redwall-Muav and Coconino Aquifer Systems of Northern 

and Central Arizona
COVER

Elevated, northwest-looking Google Earth view of Flagstaff, Arizona, in the foreground, the Coconino Plateau in the 

center, and Grand Canyon in the upper part of the image. Image Landsat from Google (2016).
Simulation of Groundwater Withdrawal 

Scenarios for the Redwall-Muav and 

Coconino Aquifer Systems of Northern and 

Central Arizona

By D.R. Pool

Prepared in cooperation with the Arizona Department of Water Resources and 

Yavapai County

Scientific Investigations Report 2016–5115

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, Director

U.S. Geological Survey, Reston, Virginia: 2016

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Suggested citation:

Pool, D.R., 2016, Simulation of groundwater withdrawal scenarios for the Redwall-Muav and Coconino aquifer systems of northern and central Arizona: U.S. Geological Survey Scientific Investigations Report 2016–5115, 38 p., 

http://dx.doi.org/10.3133/sir20165115.

ISSN 2328-0328 (online)
 iii

Contents

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

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

Climate....................................................................................................................................................2

Vegetation ..............................................................................................................................................4

Land and Water Use.............................................................................................................................4

Regional Hydrogeology.................................................................................................................................4

Aquifer Geology and Structure...........................................................................................................4

Aquifers .........................................................................................................................................5

Proterozoic Basement .......................................................................................................5

Redwall-Muav Aquifer.......................................................................................................5

Coconino Aquifer................................................................................................................6

Alluvial Aquifers..................................................................................................................6

Structure........................................................................................................................................6

Description of the Northern Arizona Regional Groundwater Flow Model...........................................6

Withdrawal Scenarios ..................................................................................................................................8

Water Uses ..........................................................................................................................................10

Scenario 1 ............................................................................................................................................14

Scenario 2 ............................................................................................................................................14

Scenario 3 ............................................................................................................................................15

Additional Scenario Assumptions....................................................................................................15

Small Private and Stock Well Withdrawals...........................................................................15

Natural Recharge Rates ...........................................................................................................16

Incidental Recharge Rates.......................................................................................................16

Drying of Model Cells During the Scenario Simulations.....................................................16

Simulated Effects of Withdrawal Scenarios ...........................................................................................18

Initial Conditions for the Scenarios .................................................................................................18

Scenario Simulation Results.............................................................................................................21

Simulated Changes in Water Levels.......................................................................................21

Scenario 1 ..........................................................................................................................21

Scenarios 2 and 3 .............................................................................................................21

Simulated Changes in Groundwater Discharge ...................................................................25

Scenario 1 ..........................................................................................................................25

Scenarios 2 and 3 .............................................................................................................26

Model Limitations................................................................................................................................27

Summary........................................................................................................................................................28

References....................................................................................................................................................30

Appendix 1.....................................................................................................................................................33 

Appendix 2.....................................................................................................................................................35 

Appendix 3.....................................................................................................................................................37
iv 

Figures

1. Map of the area within the Coconino Plateau Water Advisory Council groundwater withdrawal scenarios ..........................................................................................................................3

2. Conceptualized relations among major hydrogeologic units and the Northern Arizona 

Regional Groundwater-Flow Model layers...............................................................................7

3. Graphs of projected groundwater withdrawals by major water users for future withdrawal 

scenarios........................................................................................................................................9

4. Map of the generalized groundwater-flow system initial conditions..........................................11

5. Map of water-level change for scenario 1 in the uppermost model layer from 2006 through 

2105 near the Coconino Plateau Water Advisory Council scenario region and surrounding areas, Arizona ............................................................................................................22

6. Map of the difference in water-level change in the uppermost model layer compared with 

scenario 1 from 2006 to 2105 near the Coconino Plateau Water Advisory Council Scenario region and surrounding areas........................................................................................23

7. Graph of sources of water, storage or surface-water flow and evapotranspiration, to a 

pumped well through time.........................................................................................................26

8. Simulated changes in groundwater discharge to major perennial surface water features 

from 2006 through 2105 in and near the Coconino Plateau Water Advisory Council 

scenario region ...........................................................................................................................27

Tables

1. Withdrawal wells that were not included in the original Northern Arizona Regional Groundwater Flow Model, installed after about 2005, and wells projected to be installed from 

2006 through 2050 .......................................................................................................................12

2. Projected and simulated incidental recharge rates at waste-water treament facilities in 

the Coconino Plateau Water Advisory Council Scenario region for three groundwater 

withdrawal scenarios ................................................................................................................17

3. Simulated groundwater-flow budgets at the end of 2005 for selected regions of the Northern 

Arizona Regional Groundwater-Flow Model from Pool and others ...................................19
 v

Multiply By To obtain

Length

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 0.0002471 acre 

hectare (ha) 2.471 acre

square hectometer (hm2) 2.471 acre

square kilometer (km2) 247.1 acre

square meter (m2) 10.76 square foot (ft2) 

hectare (ha) 0.003861 square mile (mi2) 

square kilometer (km2) 0.3861 square mile (mi2)

Volume

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 0.0008107 acre-foot (acre-ft) 

cubic hectometer (hm3) 810.7 acre-foot (acre-ft) 

Flow rate

cubic meter per second (m3/s) 70.07 acre-foot per day (acre-ft/d) 

cubic meter per year (m3/yr) 0.000811 acre-foot per year (ac-ft/yr) 

cubic hectometer per year (hm3/yr) 811.03 acre-foot per year (ac-ft/yr)

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

meter per day (m/d) 3.281 foot per day (ft/d)

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

cubic meter per day (m3/d) 35.31 cubic foot per day (ft3/d) 

Specific capacity

liter per second per meter [(L/s)/m] 4.831 gallon per minute per foot [(gal/min)/ft]

Hydraulic conductivity

meter per day (m/d) 3.281 foot per day (ft/d) 

Hydraulic gradient

meter per kilometer (m/km) 5.27983 foot per mile (ft/mi) 

Transmissivity*

meter squared per day (m2/d) 10.76 foot squared per day (ft2/d) 

Leakance

meter per day per meter [(m/d)/m] 1 foot per day per foot [(ft/d)/ft]

Conversion Factors

SI to Inch/Pound
vi 

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the insert datum name (and abbreviation) here, 

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

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

here, for instance, “North American Datum of 1983 (NAD 83)”

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

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.

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

25°C).

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

or micrograms per liter (μg/L).

NOTE TO USGS USERS: Use of hectare (ha) as an alternative name for square hectometer 

(hm2) is restricted to the measurement of small land or water areas. Use of liter (L) as a special 

name for cubic decimeter (dm3) is restricted to the measurement of liquids and gases. No prefix 

other than milli should be used with liter. Metric ton (t) as a name for megagram (Mg) should be 

restricted to commercial usage, and no prefixes should be used with it.
Simulation of Groundwater Withdrawal Scenarios for the 

Redwall-Muav and Coconino Aquifer Systems of Northern 

and Central Arizona

By D.R. Pool

Abstract 

The Northern Arizona Regional Groundwater Flow 

Model was used to estimate the hydrologic changes, including 

water-level change and groundwater discharge to streams and 

springs, that may result from future changes in groundwater 

withdrawals in and near the Coconino Plateau Water Advisory 

Council study area, Coconino and Navajo Counties, Arizona. 

Three future groundwater withdrawal scenarios for tribal and 

nontribal uses were developed by the Coconino Plateau Water 

Advisory Council and were simulated for the period representing the years from 2006 through 2105. Scenario 1 assumes 

no major changes in groundwater use except for increased 

demand based on population projections. Scenario 2 assumes 

that a pipeline will provide a source of surface water from 

Lake Powell to areas near Cameron and Moenkopi that would 

replace local groundwater withdrawals. Scenario 3 assumes 

that the pipeline extends to the Flagstaff and Williams areas, 

and would replace groundwater demands for water in the area. 

The Coconino Plateau Water Advisory Council withdrawal scenarios primarily influence water levels and groundwater discharge in the Coconino Plateau basin, near the 

western margin of the Little Colorado River Plateau basin, 

and the Verde Valley subbasin. Simulated effects of the 

withdrawal scenarios are superimposed on effects of previous variations in groundwater withdrawals and artificial and 

incidental recharge. Pre-scenario variations include changes 

in water-levels in wells; groundwater storage; discharge to 

streams and springs; and evapotranspiration by plants that use 

groundwater. Future variations in groundwater discharge and 

water-levels in wells will continue to occur as a result of both 

the past and any future changes. 

Water-level variations resulting from post-2005 stresses, 

including groundwater withdrawals and incidental and 

artificial recharge, in the area of the withdrawal scenarios 

are primarily localized and superimposed on the regional 

changes caused by variations in stresses that occurred since 

the beginning of the initial stresses in the early 1900s through 

2005. Withdrawal scenario 1 produced a broad region on the 

Coconino Plateau where water-levels declined 3–5 feet by 

2105, and local areas with water-level declines of 100 feet or 

more where groundwater withdrawals are concentrated, near 

the City of Flagstaff Woody Mountain and Lake Mary well 

fields, and the towns of Tusayan, Williams, and Moenkopi. 

Water-level rises of 100 feet or more were simulated at areas 

of incidental recharge near wastewater treatment facilities near 

Flagstaff, Tusayan, Grand Canyon South Rim, Williams, and 

Munds Park. 

Simulated water-level change from 2006 through 2105 

for scenarios 2 and 3 is mostly different from water-level 

change simulated for scenario 1 at the local level. For scenarios 2 and 3, water levels near Cameron in 2105 where 

1–3 feet higher than simulated for scenario 1. Water levels at 

Moenkopi are more than 100 feet higher due to the elimination 

of a proposed withdrawal well that was simulated in scenario 

1. Scenario 3 eliminates more groundwater withdrawals in the 

Flagstaff and Williams areas, simulates 1–3 feet less waterlevel decline than scenario 1 across much of the Coconino 

Plateau, and water levels that are as much as 50 feet higher 

than simulated by scenario 1 near withdrawal wells in the Williams and Flagstaff areas.

Scenario 1 simulated the most change in groundwater 

discharge for the Little Colorado River below Cameron and 

for Oak Creek above Page Springs where declines in discharge 

of about 1.3 and 0.9 cubic feet per second (ft3/s), respectively, were simulated. Other simulated changes in discharge 

through 2105 in scenario 1 are losses of less than 0.4 ft3/s at 

the Upper Verde River, losses of less than 0.3 ft3/s at Havasu 

Creek and at Colorado River below Havasu Creek, losses 

of less than 0.1 ft3/s at Clear Creek, and increases in flow at 

the south rim springs and Chevelon Creek of less than 0.1 

and 0.3 ft3/s, respectively. Simulated changes in discharge 

for scenarios 2 and 3 are less than for scenario 1 because of 

lower rates of groundwater withdrawal. Scenario 3 resulted 

in greater groundwater discharge than scenarios 1 and 2 at 

all major groundwater discharge features from 2006 through 

2105 except for Clear and Chevelon Creeks, where the same 

groundwater discharge was simulated by each of the three 

scenarios.

Changes in groundwater discharge are expected to occur 

after 2105 to all major surface features that discharge from 

the Redwall-Muav and Coconino aquifers because change 

in aquifer storage was occurring at the end of the simulation 

in 2105. The accuracy of simulated changes resulting from 

the Coconino Plateau Water Advisory Council groundwater 

withdrawal scenarios is dependent on the persistence of several hydrologic assumptions that are inherent in the Northern 
2 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Arizona Regional Groundwater Flow Model including, but not 

limited to, the reasonably accurate simulation of (1) transmissivity distributions, (2) distributions of vertical hydraulic 

properties, (3) distributions of spatial rates of withdrawal and 

incidental recharge, (4) aquifer extents, and (5) hydrologic 

barriers and conduits. 

Introduction 

The U.S. Geological Survey (USGS) Northern Arizona 

Regional Groundwater Flow Model (NARGFM; Pool and others, 2011) was constructed for several purposes; one of which 

was to estimate the hydrologic changes—including changes 

in water levels and groundwater discharge to streams, springs, 

and vegetation—that may result from future groundwater 

withdrawals. The Coconino Plateau Water Advisory Council 

(CPWAC) would like to better understand the effect of future 

groundwater withdrawals from the primary aquifers that may 

occur though the year 2105 and has developed three future 

withdrawal scenarios for testing using the NARGFM. This 

report documents the changes in the groundwater-flow system 

simulated by the NARGFM from 2006 through 2105 using the 

three scenarios.

The analysis does not include the simulation of changes 

in the groundwater system that may result from changes in climate and land-use. Past variations in recharge rates are known 

to be important in the simulation of observed water-level 

changes in the study area (Pool and others, 2011). The effects 

of land-use change on the groundwater system are largely 

unknown and not simulated by NARGFM. Only the groundwater effects caused by changes in groundwater withdrawals 

from the primary regional aquifers and associated changes 

in incidental recharge from waste-water treatment facilities 

are simulated. By focusing only on the effects of changes in 

groundwater withdrawals, the CPWAC will be able to better assess changes in groundwater discharge and water levels 

in wells that may result from each of the three withdrawal 

scenarios. Inclusion of climate scenarios that are beyond the 

control of CPWAC would likely complicate the analysis and 

were therefore avoided.

The study area is a small part of the region covered by 

the NARGFM, which includes most of northern and central 

Arizona, but also adjacent parts of western New Mexico and 

southern Utah. The areal extent of the analysis of the effects 

of the CPWAC withdrawal scenarios is the boundary of the 

Coconino Plateau Partnership (fig. 1) and adjacent areas, 

which includes the Coconino Plateau and parts of the watersheds of the Verde and Little Colorado Rivers, and the western 

part of Navajo County. The Coconino Plateau is a region of 

uplifted layered sedimentary rock overlain by layered volcanic 

rocks and dissected by deep canyons. The layered sedimentary 

rocks are deformed by faulting and uplift. In several alluvial 

basins drained by the Verde and Salt River systems, the deformation has resulted in thick accumulations of sediments. 

Land surface altitudes in the CPWAC study area range 

from more than 7,000 feet (ft) on San Francisco Mountain, 

the Mogollon Rim south of Flagstaff, and along the south 

rim of Grand Canyon to about 3,100 ft at the confluence of 

Beaver Creek and about 1,500 ft at the Colorado River west 

of Havasu Creek (fig. 1). North of the Mogollon Rim, the 

land surface generally slopes gently toward deep canyons at 

the Little Colorado and Colorado Rivers. To the south of the 

Mogollon Rim, the land surface drops more steeply to the 

Verde Valley.

The analysis is restricted to the primary regional Redwall-Muav and Coconino aquifers that are accessed by the 

major water users in the area. Other, more localized aquifers 

such as the Navajo Sandstone aquifer at Black Mesa, volcanic 

rock aquifers near Flagstaff and Williams, and alluvial aquifers along streams are not considered in the analysis

Springs and streams that discharge groundwater from 

the regional aquifers of the area are included in this analysis. 

The major rivers in the study area (fig. 1) are the Colorado 

River and Little Colorado River to the north of the Mogollon Rim, and the Verde River to the south. The perennial 

streams are largely supplied with groundwater discharge from 

springs, but flow is also supported by runoff from numerous 

intermittent and ephemeral streams. Groundwater discharge 

is also distributed along many stream reaches that gain flow. 

The primary perennial streams considered in this analysis 

include the Colorado River, lower and middle parts of the 

Little Colorado River, the Upper Verde River, and Oak Creek. 

Streams and springs that are tributaries of the Colorado River 

and are considered in the analysis include Havasu Creek and 

several springs at the south rim of Grand Canyon. Streams 

and springs that are tributaries of the Little Colorado River 

and are considered in the analysis include the lower perennial parts of Clear Creek and Chevelon Creek. Oak Creek is a 

tributary of the Verde River. 

Climate

The climate of the study area is primarily arid to semiarid with large spatial and temporal variations of temperature 

and precipitation. Climate conditions are strongly correlated 

with altitude; moderate summers and severe winters are at 

higher altitudes, and extreme summer heat and mild winters 

are at lower altitudes. Microclimates are common in the study 

area because of local controls on the amount of solar radiation 

and precipitation reaching the land surface in mountainous 

terrain and in the deep canyons.

The spatial distribution of precipitation, derived from the 

Basin Characterization Model of Flint and Flint (2008), is primarily influenced by the direction of approaching winds and 

orographic uplift of air masses. Average annual precipitation 

varies from about 7–15 inches in the basins, to about 20–37 

inches in the mountains and higher altitudes of the Coconino 

Plateau. Long term precipitation in the study area is dominated by extended below-average periods of precipitation 
Introduction 3

113° 112° 111°

37°

36°

35°

Holbrook Winslow

Flagstaff Defiance

Uplift

Rim

Kaibab

Plateau

Coconino

Plateau

Colorado Plateau

MODEL COLUMNS

1-400

MODEL ROWS

1-600

ARIZONA

NO-FLOW

BOUNDARY

Mogollon

EXPLANATION

Town or landmark

Simulated stream

Perennial streams

Major faults

Folds

Coconino Plateau Partnership area

ADWR Groundwater basin and subbasin boundary

Coconino County boundary

Model layer 1 active extent

Model layer 2 active extent

Model layer 3 active extent

0 5 10 20 30 40 MILES

0 10 20 40 60 80 KILOMETERS

Little 

Chino 

sub-basin

Verde Valley

sub-basin

Coconino 

Plateau 

basin

Kaibab

Plateau 

Little Colorado River 

Plateau 

basin

San Francisco 

Mountain

Red Gap

Ranch

well field

Lake Mary

well field

Woody 

Mountain

well field

Black 

Mesa 

Big Chino 

sub-basin

Verde River

Oak Creek

River

Colorado eltti L

Chevelon

Clear

Creek

Cr

Beaver

eek

West

Creek

ClearCreek

Supai

Grand Canyon

Village

Blue Springs 

Complex

Tusayan

Valle

Cameron

Winona

Sedona

Flagstaff

Leupp

Winslow

Munds 

Park

Red Lake

Williams

Prescott

Parks

Moenkopi

Page

Tuba City

Mogollan Rim 

COCNINO COUNTY

MESA BUTTE FAULT

YAVAPAI COUNTY

NAVAJO COUNTY

River

Colorado Havasu

Creek

County boundaries of the United States, USGS 2000 National Atlas, 1:2,000,000-scale resolution, 2002, USGS; 

Towns from USGS Geographic Names Information System, 1981. Coordinate System: NAD 1927 UTM Zone 12N. 

Projection: Transverse Mercator. Datum: North American 1927. False Easting: 500,000.0000. False Northing: 0.0000.

Central meridian: -111.0000. Scale factor: 0.9996. Latitude of origin: 0.0000. Units: meters

Perennial streams from Arizona Department of Water Quality, 2015,

scale 1:100,000; Groundwater basin and sub-basin boundaries from

Arizona Department of Water Resources, 2008, scale 1:100,000;

Faults and folds from USGS SIR 2010–5180

Figure 1. Map of the area within the Coconino Plateau Water Advisory Council groundwater withdrawal scenarios, 

including Arizona Department of Water Resources (ADWR) groundwater basins, model layer extents, and inset map of 

Arizona showing Northern Arizona Regional Groundwater Flow Model model grid and boundaries. 
4 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

interspersed with occasional above-average periods of precipitation (Blasch and others, 2006). Annual precipitation is 

distributed between a summer monsoon period and a winter 

frontal storms period. The summer monsoon (also known 

as the North American Monsoon, or the Southwestern, 

Arizona, or Mexican Monsoon), generally begins in early 

July and extends through September, and includes precipitation from convective storms that are characteristically short 

lived (less than a few hours), but can be intense (precipitation greater than 1 in/hr), and localized (tens of square 

miles). The winter frontal season from November through 

March produces storms that are characteristically longer 

(12–48 hr), less intense (precipitation less than 0.25 in/hr), 

and more regional in extent (hundreds of square miles) than 

summer convective storms. Precipitation also can fall during 

October and November as a result of both tropical disturbances from the southern Pacific Ocean and winter frontal 

storms from the north Pacific. Although precipitation during 

this period can be a substantial part of the annual total, the 

atmospheric conditions that result in precipitation do not 

happen regularly. The average annual rainfall rate is greater 

than the average annual snowfall rate for all climate stations 

in the study area. The greater rainfall rate is attributed to 

warm annual mean temperatures. This greater rate is true in 

the higher altitudes where the ratio of rainfall to snowfall is 

about 3 to 1, and in the basins where the ratio is greater.

Average annual temperatures range from about 68 °F in 

the basins to 43 °F at higher altitudes and are inversely correlated with altitude. Average annual minimum temperatures 

were recorded as low as 36 °F on the north rim of the Grand 

Canyon and average annual maximum temperatures have 

been measured as warm as 78 °F in the Verde Valley. Large 

differences between the minimum and maximum daily temperatures are characteristic of the area.

Vegetation

The distribution of vegetation in the study area is 

influenced by temperature and by water availability. Thus, 

plant communities are distributed on the basis of differences 

in latitudes, altitudes, and topography. Basins along the 

Verde and Salt Rivers are inhabited by desert scrub characteristic of the Sonoran desert. Piñon-juniper woodlands 

and chaparral are primarily present in the middle altitudes 

(about 3,900–5,600 ft). The predominant type of vegetation 

at altitudes above 5,600 ft is montane coniferous forest on 

the Mogollon Rim and across a large region near the San 

Francisco Mountain, Flagstaff, and Williams. Vegetation 

that taps groundwater supplies, phreatophytes, occur along 

perennial and intermittent streams. Important phreatophytes 

of the area include cottonwood, willow, sycamore, tamarisk, 

and mesquite.

Land and Water Use

Population—The estimated population of Coconino 

County was 136,539 in 2013 (U.S. Census Bureau, 2015), 

which includes most of the area of analysis. 

Land Use—Native American reservations account 

for about 68 percent of the lands in the Coconino Plateau 

Partnership study area. About 26 percent of the land in the 

area is publicly owned; 14 percent is managed by the U.S. 

Department of Agriculture (USDA) Forest Service, 7 percent 

is managed by the National Park Service, and 4 percent is 

managed by the State of Arizona. Recreation, forest, cattle 

and sheep ranching, mining, and urban development are the 

largest land uses in the region. Privately held lands account 

for about 7 percent of the total.

Water Use—Groundwater (including spring water) 

withdrawals in the study area are primarily for industrial and 

tribal/municipal/domestic water use. Near population centers, 

groundwater is supplied primarily by private and municipal water companies. Wells are used in some rural areas to 

obtain groundwater for domestic and stock use. Total well 

withdrawals in the CPWAC area were about 12,500 acre-ft 

during 2006–10. About 10,800 acre-ft were withdrawn from 

the regional aquifers simulated by NARGFM on an annual 

basis during 2006–10. About 1,700 acre-ft of the total were 

withdrawn from aquifers other than the regional aquifers 

simulated by NARGFM. Surface water is also a water supply 

source at Page, Flagstaff, and Williams. A source of water 

for Grand Canyon Village is spring discharge from the North 

Rim of Grand Canyon, which is imported to the study area 

through a pipeline. A portion of the water used for municipal, 

tribal, and domestic purposes was returned to the primary 

regional aquifers as incidental recharge through waste-water 

treatment facilities and septic systems.

Regional Hydrogeology

Descriptions of the regional hydrogeology of northern 

Arizona include several elements—aquifers and confining 

units, rates and distribution of recharge, rates and distributions of discharge, and groundwater flow through the aquifers 

between recharge and discharge areas. Each of the elements 

of hydrogeology are briefly discussed in this report. More 

complete descriptions of each element may be found in Pool 

and others (2011) and in greater detail in numerous reports 

for subregions of the study area. 

Aquifer Geology and Structure 

The stratigraphic sequence in the study area includes 

Proterozoic metamorphic and igneous rocks that are overlain by a sequence of Cambrian to Permian sedimentary 

rocks. Late Tertiary volcanic rocks overlay the older rocks in 

places, especially along the Mogollon Rim. Sequences of late 
Regional Hydrogeology 5

Tertiary alluvial basin deposits, hundreds to thousands of feet 

thick, overlie the older rocks in the alluvial basins along the 

Verde and Salt River drainages. A more complete description 

of the rock units and aquifers of the study area can obtained 

from Hart and others (2002), Leake and others (2005), Parker 

and others (2005), Wirt and others (2005), Blasch and others 

(2006), Bills and others (2007), and Pool and others (2011).

Aquifers

Most rock units in the study area contain some waterbearing zones. However, structural deformation has reduced 

the continuity of saturated units across the study area. 

Groundwater systems of the study area are more complex 

than is indicated by the fairly simple layering of the rocks that 

contain the groundwater systems. The complexity is because 

of variations in stratigraphy, lithology, and geologic structure 

(Bills and others, 2007). Aquifers are briefly described here 

but are described in greater detail in the NARGFM report 

(Pool and others, 2011). Stratigraphic relations of the rock 

units are shown in figure 7 of Pool and others (2011). The 

Redwall-Muav aquifer (locally known as the R-M aquifer) 

and the Coconino multiple aquifer system (locally known as 

the C aquifer) are the primary aquifers in the study area. The 

Redwall-Muav and Coconino aquifers are the primary regional 

aquifers on the Coconino Plateau in the study area (Cooley 

and others, 1969; Cooley, 1976). Both the Redwall-Muav 

aquifer and the Coconino aquifer have internal southeastnorthwest trending groundwater divides that are coincident 

with or near the Mogollon Rim, and divide the regional 

groundwater-flow system into parts that flow northward 

toward the Colorado and Little Colorado Rivers, and southward toward the Verde and Salt Rivers. Other local aquifers 

lie adjacent to the regional aquifers and are hydraulically 

connected including thick alluvial deposits in basins of the 

Verde River drainage system, thin stringers of Quaternary 

alluvium along major streams, and fractured Proterozoic sediments, granite, and metamorphic rocks that mainly occur in 

upland areas (fig. 2). Other local aquifers that are hydraulically 

disconnected from the regional aquifer system and from each 

other occur within Proterozoic rocks, the lower Supai Formation, the Coconino Sandstone, the Kaibab Limestone, volcanic 

rocks, and Quaternary alluvium. These local, isolated aquifers 

generally are small and thus are unsuitable as long-term water 

supplies; however, these aquifers are used extensively to meet 

local water demands. These local disconnected aquifers are 

taken into consideration in the regional groundwater-flow 

system because groundwater that discharges from the local 

aquifers can percolate downward to the underlying regional 

aquifer system. The downward percolation of water from shallow local aquifers is an important process in the large region 

covered by volcanic rocks in the Flagstaff, Williams, and 

much of the Mogollon Rim areas. 

Proterozoic Basement

Proterozoic metamorphic and igneous rocks form the 

underlying confining bed for the Redwall-Muav, Coconino, 

and basin-fill aquifers, and, in general, do not store or transmit substantial amounts of water. Only in a few areas with 

significant fracturing is water found in quantities sufficient for 

withdrawal. One of these areas is along the Inner Gorge of the 

Grand Canyon where several small springs and seeps discharge from fractured Precambrian granites and metamorphic 

rocks.

Redwall-Muav Aquifer

The Redwall and Muav Limestones are the primary 

water-bearing rock units in the region of the Coconino Plateau, 

and underlie the Coconino aquifer in the remainder of the Colorado Plateau. Cooley (1976) defined the Redwall and Muav 

Limestone multiple-aquifer system as the saturated to partly 

saturated and hydraulically connected Redwall, Temple Butte, 

and Muav Limestones. Other regional studies have broadened the extent of the aquifer to include several hydraulically 

connected limestone, sandstone, and shale units including the 

Tapeats Sandstone, Bright Angel Shale, Muav Limestone, 

Temple Butte Limestone, Martin Limestone, and Naco Formation (McGavock and others, 1986; Parker and others, 2005). 

The Redwall Limestone occurs throughout the study area and 

is the upper rock unit of the Redwall-Muav aquifer where 

the Naco Formation is absent. The Temple Butte Limestone 

and the Muav Limestone underlie the Redwall Limestone 

near the Grand Canyon in the area of the Coconino Plateau. 

South of the Grand Canyon, the Temple Butte Formation thins 

southward and overlies the Martin Limestone or is absent, and 

the Muav and Redwall Limestones are in direct contact. The 

Martin Limestone is mainly in the central and southern part of 

the plateau and thickens to the south. 

The Bright Angel Shale and Tapeats Sandstone underlie the Martin, Temple Butte, and Muav Limestones in the 

central and western parts of the study area. The Bright Angel 

Shale is several hundred feet thick; however, it is not a major 

water-bearing unit because it is composed of very fine-grained 

sediments that impede the downward migration of water 

(Huntoon, 1977). Nevertheless, dozens of springs discharge 

from the Bright Angel Shale in Grand Canyon from fine 

grained sandstone, sandy siltstone, and bedding plane fractures (Monroe and others, 2005). The Tapeats Sandstone is a 

major water-bearing unit in places. The Tapeats Sandstone is a 

continuous unit along the south and north rims of Grand Canyon. South of Grand Canyon, the Tapeats Sandstone is mainly 

present as isolated erosion remnants overlying Proterozoic 

rocks. The Tapeats Sandstone is believed to be hydraulically 

connected to the overlying Redwall and Muav Limestones 

through faults and fractures, and where the Bright Angel Shale 

is thin or absent.

Groundwater primarily enters the Redwall-Muav aquifer 

through downward leakage from overlying units by way of 

faults, fractures, and other geologic structures that create 
6 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

secondary porosity and conduits for groundwater flow through 

the lower Supai Formation, which is otherwise primarily a 

confining unit. Groundwater flow in the aquifer is substantially 

enhanced by faults, fractures, and solution channels. Areas of 

substantial faulting and fracturing are (1) along the Mesa Butte 

Fault Zone; (2) across the Havasu Creek drainage basin from 

Williams to Supai; (3) along the faults near Tusayan; (4) in 

the Cameron area coincident with several large monoclines; 

and (5) south of Flagstaff in association with extensional 

basins (Cooley, 1976; Ulrich and others, 1984; Billingsley, 

2000; Bills and others, 2000; Billingsley and others, 2006). 

The aquifer is anisotropic and confined in much of the study 

area. Small parts of the aquifer are unconfined where the 

aquifer rocks crop out. Wells drilled along extension faults 

and fractures typically penetrate zones of increased transmissivity because of the solution-enhanced permeability (Errol L. 

Montgomery and Associates, 1999).

Coconino Aquifer

The Coconino aquifer is the sequence of rock units 

between the Moenkopi Formation and the lower Supai Formation (McGavock and others, 1986; Bills and others, 2000, 

2007; Bills and Flynn, 2002). The primary water producing unit is the Coconino Sandstone; however, the overlying 

Kaibab and Toroweap Limestones and the underlying Schnebly Hill Formation and upper and middle Supai Formations 

of the Supai Group can be locally major water producing 

units (Leake and others, 2005). The lower Supai Formation 

typically forms a confining unit that separates the Coconino 

aquifer from the underlying Redwall-Muav aquifer and local 

Proterozoic crystalline aquifers. West of the Mesa Butte Fault, 

the primary water-bearing zones of the Coconino aquifer are 

locally present as perched aquifers (Bills and others, 2007) but 

are unsaturated across broad regions. The Coconino aquifer 

thins toward the east, however the exact eastern boundary is 

uncertain because water-level and geologic data are meager. 

Groundwater in the Coconino aquifer is unconfined except 

where the base of the Moenkopi Formation falls below the 

potentiometric surface across much of the region north of the 

Little Colorado River. Many wells drilled into the confined 

part of the aquifer flowed at land surface before significant 

development of the groundwater supplies (Mann and Nemecek, 1983; Mann, 1976). Groundwater flow in the Coconino 

aquifer is locally enhanced by fractures and faults (Bills and 

others, 2000; Hoffmann and others, 2005; Kaczmarek, 2003; 

Leake and others, 2005). 

Alluvial Aquifers

Alluvial basin aquifers are present in basins that lie to 

the south of the study area but are of minor importance in 

the CPWAC study area. Alluvial aquifers of local importance 

include thin stringers of Quaternary flood-plain alluvial and 

terrace deposits that occur along major streams. Where unsaturated, such as along perennial stream reaches, these highly 

permeable deposits are effective conduits for the transmission 

of infiltrated streamflow to the underlying aquifer. Perched 

aquifers may form locally where the Quaternary alluvium overlies low permeability rocks.

Structure

Regional tectonic stresses have shaped the landscape of 

the study area, disturbed the stratigraphic sequence, formed 

basins where sediments accumulated, and formed local zones 

of weakness that resulted in volcanism. These regional stresses 

have also influenced the groundwater-flow system through the 

creation of faults and fractures that can locally be flow barriers 

or conduits for groundwater flow. Northeast-, north-, and northwest-striking faults and other fractures dominate the structure 

of the study area (Gettings and Bultman, 2005). Extensional 

stresses that have weakened the regional pre-Tertiary sediments 

have enabled large amounts of late Tertiary and Quaternary 

intrusive and volcanic rocks to reach the surface (Wolfe and 

others, 1987a,b). In addition, zones of weakness are continuing 

to expand, lengthen, and deepen, in some areas into canyons, 

from continued interaction with water. Groundwater movement 

along the expanded zones of weakness enhances the preferential flow paths through dissolution of carbonate rocks.

Description of the Northern Arizona 

Regional Groundwater Flow Model

The NARGFM was developed using the USGS groundwater model MODFLOW-2000 (Harbaugh and others, 2000) 

and MODFLOW-2005 (Harbaugh, 2005). The model grid 

includes 600 rows and 400 columns of finite-difference cells, 

each 1-kilometer square, in the horizontal dimension. The 

model grid is rotated 60° in the counter-clockwise direction 

about the geographic origin of the grid at Universal Transverse 

Mercator zone 12 easting 660,000 m and northing 3,580,000 m. 

Rotation of the grid allows for row and column alignment with 

the assumed principal directions of the hydraulic conductivity 

tensor. The origin of the model grid lies at the outer corner of 

the cell at row 600 and column 1. Model rows are incremented 

from the cell at row 1, column 1 to row 600 in a southeasterly 

direction. Model columns are incremented from the cell at 

row 1, column 1, to column 400 in a northeasterly direction. 

The model was constructed using units of meters for length 

and days for time. For this report, descriptions of values in the 

model are given in units of feet for length and days for time.

NARGFM uses three model layers to simulate the primary 

hydrogeologic units across the model domain (fig. 2). Model 

layer 1 represents the upper part of the Coconino aquifer 

including the Coconino Sandstone and Kaibab Limestone 

and equivalent units in the Colorado Plateau structural province and adjacent areas, and the upper part of basin fill in the 

alluvial basins of the transition zone. Model layer 2 represents 

the lower part of the Coconino aquifer including the upper and 
Description of the Northern Arizona Regional Groundwater Flow Model 7

middle Supai Formation and equivalent units in the Colorado 

Plateau structural province and adjacent areas, and the lower 

part of basin fill in the alluvial basins of the transition zone. 

Model layer 3 represents the Redwall-Muav aquifer and older 

crystalline and sedimentary rocks where the Redwall-Muav 

aquifer is absent across much of the transition zone and eastern part of the Colorado Plateau structural province. For more 

detail, see Pool and others (2011).

Boundaries of NARGFM include no-flow boundaries at 

the model margins and internal flow boundaries at perennial 

streams. No-flow boundaries correspond with low permeability rocks and groundwater divides, and constrain all of the 

simulated recharge in the model to flow toward discharge at 

internal flow boundaries and wells. Internal flow boundaries 

are the primary controls that determine directions of groundwater flow. The distributions of internal flow boundaries 

relative to areas of variable flux at wells and recharge areas 

also partly determine the rates of change in discharge that 

result from the variable flux. The other important factors that 

determine rates of change are aquifer hydraulic and storage 

properties.

Within the area of the CPWAC withdrawal scenarios 

and surrounding areas, the major simulated aquifers are the 

Coconino aquifer and the Redwall-Muav aquifer. The upper 

part of the Coconino aquifer is simulated as model layer 1 

only where the primary hydrogeologic units are regionally 

saturated in the Little Colorado River Plateau basin, primarily 

in the region northeast of the Little Colorado River. The lower 

part of the Coconino aquifer is simulated as model layer 2 

where the upper and middle Supai Formations are regionally 

saturated in the area east of about Cameron and Williams. In 

the Verde Valley, model layer 2 includes the saturated parts of 

the upper and middle Supai Formations outside of the alluvial 

basin, and the saturated part of the sand and gravel facies of 

the Verde Formation in the alluvial basin. The Redwall-Muav 

aquifer is simulated as model layer 3 throughout most of the 

region of the CPWAC withdrawal scenarios and surrounding 

areas except for a few areas where the Redwall-Muav aquifer 

is absent and model layer 3 represents underlying rocks along 

parts of the Colorado River.

Aquifer properties are represented in the NARGFM using 

the Layer-Property Flow Package of MODFLOW. Important aquifer properties included in the model are hydraulic 

conductivity, specific storage, and specific yield. Hydraulic 

conductivity can be different in the two principal directions 

of the model grid, along rows and columns. Directions and 

magnitude of primary hydraulic conductivity directions across 

the area of the CPWAC withdrawal scenarios is influenced by 

geologic structure and secondary porosity. Model layer 3 is 

simulated with values along columns that are as much as 10 

VERDE VALLEY SUB-BASIN

QUATERNARY ALLUVIUM

UPPER BASIN FILL COCONINO SANDSTONE

LAYER 1

LAYER 2

LAYER 3

FLUVIO-LACUSTRINE

 FACIES OF THE 

VERDE FORMATION

LOWER BASIN FILL

COCONINO PLATEAU AND MOGOLLON RIM NARGFM MODEL

LAYERS

KAIBAB AND TOROWEAP 

FORMATIONS 

VOLCANIC ROCKS

 

UPPER AND MIDDLE SUPAI FORMATIONS

MESOZOIC CONFINING 

BEDS

LOWER SUPAI FORMATION

REDWALL-MUAV LIMESTONE

PROTEROZOIC SEDIMENTS, GRANITE, AND METAMORPHIC ROCKS

Water table

Figure 2. Conceptualized relations among major hydrogeologic units and the Northern Arizona Regional Groundwater-Flow 

Model (NARGFM) layers. 
8 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

times the values along rows in the region for the Coconino 

Plateau. Hydraulic conductivity for model layers 1 and 2 are 

simulated as equivalent along rows and columns across large 

regions, but variable in the area of the Mogollon Rim where 

values along columns in some areas are as much as 5 times 

the values along rows. In the Oak Creek area, values along 

rows are locally 3 times greater than along columns. Mean 

vertical hydraulic conductivity in all layers is lower than mean 

horizontal hydraulic conductivity along rows and columns. 

In MODFLOW, specific storage is applied where the aquifer 

is confined, as indicated by head or water level above the top 

of the aquifer. The product of specific storage and saturated 

thickness is the aquifer storage coefficient. The USGS has 

defined the storage coefficient of an aquifer as, “the volume 

of water it releases from or takes into storage per unit surface area of the aquifer per unit change in the component of 

head normal to that surface” (http://water.usgs.gov/admin/

memo/GW/gw55.28.html). The mechanisms for these storage 

changes are compression and decompression of the aquifer 

skeleton and water. Similarly, specific yield is applied where 

the aquifer is unconfined, as indicated by head or water level 

below the top of the aquifer. Specific yield is the quantity 

of water released per unit volume of the aquifer by gravity 

drainage from lowering the water table. The uppermost active 

layer of the three model layers across the area of the CPWAC 

withdrawal scenarios is simulated as unconfined except in 

the eastern part of the area where the Moenkopi Formation is 

an important regional confining unit overlying the Coconino 

aquifer. In areas where the uppermost active model layers 1 

or 2 are simulated as unconfined, underlying model layers 

2 and 3 are simulated as confined. Specific yield values for 

model layers 1 and 2 range from 0.10 to 0.20 in the area of the 

CPWAC withdrawal scenarios. Low values of specific yield, 

less than 0.02, are simulated for layer 3 where it is the only 

active model layer.

Saturated thickness also is an important factor in calculating groundwater movement in the model. Where heads are 

below the top of the model layer, saturated thickness is the difference between the model-calculated head or water level and 

the specified bottom of the aquifer. Mean saturated thickness is 

much larger in layers 2 and 3 than in layer 1 in the area of the 

CPWAC withdrawal scenarios and surrounding areas.

Discharge of groundwater in NARGFM is simulated as 

occurring naturally along streams and springs simulated with 

the stream (Prudic, 1989) and drain packages (Harbaugh, 

2005), and through evapotranspiration (ET). The stream 

package keeps track of available flow and calculates stream 

stage in each section or reach of stream that crosses a model 

cell. If leakage of water from the stream exceeds available 

streamflow, no further leakage is allowed from downstream 

reaches until the point where there is additional water available to the downstream reaches from tributary inflow or flow 

of groundwater into the stream. The stream package is used 

to simulate discharge to streams that have significant reaches 

where streamflow infiltrates the channel and recharges the 

aquifer. Groundwater discharged at features simulated using 

the drain package is permanently removed from the simulated 

flow system and not available to recharge through downstream 

stream reaches like in the stream package. The drain package 

is used to simulate streams and springs that have no important 

losing reaches. Important discharge features in the region of 

the CPWAC withdrawal scenarios that are simulated using the 

stream package include the Verde and Little Colorado Rivers 

and major perennial tributary streams. Important discharge 

features that are simulated using the drain package include 

the Colorado River, Havasu Creek, and several major springs 

in tributary streams. Input for the stream package includes 

specification of quantities for each of the stream reaches such 

as the elevations of the top and bottom of the streambed, 

streambed conductance, stream width, and Manning’s roughness coefficient. Input for the drain package includes the 

elevation and conductance of the spring or streambed. ET is 

simulated in riparian areas where there are shallow depths to 

the water table along the Verde and Little Colorado Rivers and 

major perennial tributary streams. Input for each model cell 

where ET is simulated includes maximum ET rate, elevation 

of maximum ET rate, and maximum depth of ET. Maximum 

rates of ET assigned to model cells in the area of the CPWAC 

withdrawal scenarios and nearby regions were 6.54 × 10-4 ft/d. 

Elevation of maximum rates of ET were assigned as 4.9 ft 

below the land surface in the model cell. Maximum depth of 

ET was simulated as 16.4 ft. For more details on representation of features with the stream, drain, and ET packages in the 

NARGFM, see Pool and others (2011).

Withdrawal Scenarios

Three future water demand scenarios (fig. 3, appendixes 

1–3) for tribal and nontribal uses, including groundwater 

withdrawals, were developed by the CPWAC for much of 

Coconino County, all of which lies within the area simulated 

by the NARGFM. Projected withdrawal rates were developed 

for each decade from 2006 to 2105 for all three scenarios 

on the basis of population projections supplied by tribal 

and nontribal agencies. For the scenario simulations, future 

withdrawals are assumed to derive from existing exempt and 

nonexempt wells and many new withdrawal wells that are 

anticipated to be developed in several areas (fig. 4, table 1). 

The simulations also include estimated changes in incidental 

recharge of effluent from sewage plants and golf courses. 

The simulated scenarios do not included demands on water 

supplies that are not simulated by NARGFM such as surface 

water supplies and groundwater supplies from aquifers that are 

disconnected from the regional aquifers, including the Navajo, 

Dakota, and other shallow aquifers.

The scenarios include projected groundwater withdrawals from the primary regional aquifers by major water users 

for each decade from 2010 to 2049 followed by a 55-year 

period of stable withdrawals from 2050 to 2105. Groundwater 

withdrawals are simulated from only the regionally extensive 
Withdrawal Scenarios 9

SIRPool_fig 03

0

5,000

10,000

15,000

20,000

25,000

30,000

0

5,000

10,000

15,000

20,000

25,000

30,000

0

5,000

10,000

15,000

20,000

25,000

30,000

A

B

C

2006–2009 2010–2019 2020–2029 2030–2039 2040–2049 2050–2105

Time, in years from 2006–2105

Other

EXPLANATION

Hualapai Tribe

Hopi Tribe

Havasupai Tribe

Williams, Valle, Tusayan

Navajo Tribe

Communities near Flagstaff

City of Flagstaff

Withdrawals, in acre-feet per year

Figure 3. Graphs of projected groundwater withdrawals by major water users for future 

withdrawal scenarios. (A) Scenario 1, (B) Scenario 2, and (C) Scenario 3.
10 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Coconino and Redwall-Muav aquifers and overlying locally 

extensive volcanic rock aquifers that likely discharge to the 

underlying regional aquifers. Most of the wells, from which 

groundwater withdrawal for each scenario would be derived, 

lie within two groundwater basins defined by the Arizona 

Department of Water Resources (ADWR)—the Coconino 

Plateau basin and the Little Colorado River Plateau basin. 

Some of the wells lie within the Verde Valley subbasin. Parts 

of Coconino County that were not included in the scenarios as 

demand areas are near Sedona in the Verde Valley subbasin, 

on the Mogollon Rim areas in eastern and southeastern parts 

of the County, and the Kaibab Plateau north of the Grand 

Canyon.

In addition to the withdrawal scenarios for the CPWAC 

area, non-CPWAC area groundwater withdrawals and related 

incidental recharge also need to be included in the simulations. 

For each of the three scenarios, non-CPWAC groundwater 

withdrawals were assumed to remain unchanged from the rates 

simulated during the final NARGFM stress period, 2000–05. 

This assumption recognizes that past and future non-CPWAC 

withdrawals will have future effects on the hydrologic features 

of interest in the CPWAC area, and simulates the effects of 

those withdrawals and incidental recharge. This assumption 

also facilitates the evaluation of groundwater management 

practices within the CPWAC area separate from change caused 

by practices outside of the area of interest.

The intent of the scenario simulations is to evaluate 

changes in water levels in the regional aquifers and changes in 

groundwater discharge to streams and springs that may result 

from possible future variations in groundwater withdrawals in the CPWAC area. Future changes, however, will also 

result from past and future variations in recharge rates and 

groundwater withdrawals in areas both within and outside of 

the CPWAC area. These past changes that affect future change 

make the interpretation of the scenario results more complex. 

In order to simplify the scenario results, it was advantageous 

to eliminate the effects of past recharge variations from the 

analysis. Therefore, the effects of past recharge variations are 

eliminated from this analysis by simulating pre-2006 conditions using an average-annual recharge rate and using those 

2005 ending conditions as the initial conditions for the scenarios. Additional scenarios other than those simulated, would 

be required to evaluate the post-2005 changes that result from 

pre-2006 variations in withdrawals and recharge throughout 

the model area, future variations in withdrawal rates outside 

of the CPWAC area, and the effects of future variations in 

recharge rates.

Change resulting from variations in groundwater withdrawals and incidental recharge for both past conditions and 

future variations in each CPWAC scenario is determined 

by comparing the changes in water levels and groundwater 

discharge resulting from each scenario. This type of analysis 

requires an assumption of a linear system response in the area 

of interest throughout the simulation for each of the scenarios. 

Nonlinear changes that may occur include significant changes 

in the saturated thickness of aquifers and changes in discharge 

to surface features such as streams, springs, and riparian 

vegetation. This assumption is likely valid for the CPWAC 

area because the rates of groundwater withdrawals in the area 

are a small fraction of the overall water budget or recharge 

rates. This assumption would not likely be true for some local 

parts of the NARGFM where withdrawal rates are large in 

comparison to local groundwater budgets such as in the Little 

Chino. The CPWAC is most interested in the possible effects 

of groundwater withdrawals for each scenario during the time 

period through 2105. 

Water Uses

Water use from wells that draw from the Redwall-Muav 

and Coconino aquifers in the CPWAC scenarios is categorized 

as tribal and nontribal. Annual tribal withdrawals from these 

aquifers were less than 10 percent of the nontribal withdrawals 

prior to 2010. The scenarios anticipate that annual withdrawals 

by the tribes will increase faster than the nontribal withdrawals during 2010–50, but will remain less than 20 percent of 

nontribal annual withdrawals. 

The largest pre-2010 tribal uses derived from the 

Redwall-Muav and Coconino aquifers primarily include 

groundwater withdrawals of a few hundred acre-feet per year 

(ac-ft/yr) from the Coconino aquifer for the Navajo Tribe in 

areas near Leupp, Cameron, Bodeway, and at Twin Arrows 

Casino west of the City of Winslow. Other pre-2010 tribal uses 

include less than 200 ac-ft/yr from the Redwall-Muav aquifer 

for the Havasupai Tribe in the western part of the Coconino 

Plateau and less than 10 ac-ft/yr from nonregional aquifers 

for the Hualapai Tribe in the western part of the Coconino 

Plateau. The scenarios anticipate the most potential growth, 

more than 3,000 ac-ft/yr by 2050, in tribal withdrawals from 

the Coconino aquifer in the area to the south of Leupp, on the 

Navajo Nation. Other tribal withdrawals from the RedwallMuav and Coconino aquifers are anticipated to increase to 

about 205 ac-ft/yr by 2050. New wells are also anticipated 

to tap the Redwall-Muav aquifer for the Havasupai Tribe, 

increasing use to 25 ac-ft/yr, and the Hualapai Tribe, increasing use to 10 ac-ft/yr. Pre-2010 groundwater supplies for the 

Hopi Tribe were primarily derived from the Navajo aquifer, 

which is not simulated in the NARGFM. However, a new 

well is anticipated to derive as much as 170 ac-ft/yr from the 

Coconino aquifer near Moenkopi for Hopi Tribe use. 

The largest users of groundwater from the Coconino and 

Redwall-Muav aquifers in the scenario area are nontribal. 

Several thousand acre-feet per year are withdrawn for use by 

the City of Flagstaff and several water companies near Flagstaff, the City of Williams, and other communities including 

Tusayan, Valle, and Grand Canyon Village. The City of Flagstaff withdraws the greatest amount of groundwater in the area 

and derives its supply mostly from the Coconino aquifer in the 

Woody Mountain well field, Lake Mary well field, and local 

wells within the city limits, which is known as the Local well 

field (fig. 4). Groundwater is also withdrawn by Flagstaff from 
Withdrawal Scenarios 11

113° 112° 111°

37°

36°

35°

G

G

G

G

G

G

G

G

GG

G G

G G

GG G G

G

G

G

G

GG

G

G

Fort Rock

sub-basin

Fox Ranch

Woody Mountain

well field

Lake Mary

well field

Fort Rock

sub-basin

Little 

Chino 

sub-basin

Verde Valley

sub-basin

Coconino 

Plateau 

basin

Little Colorado River 

Plateau 

basin

Red Gap

Ranch

well field

Flagstaff

local

well field

Big Chino 

sub-basin

Verde River

Oak Creek

River

Colorado eltti L

Chevelon

Clear

Creek

Creek

Beaver

West

Creek

ClearCreek

Supai

Grand Canyon

Village

Blue Springs 

Tusayan

Valle

Gray Mountain

Cameron

Winona

Sedona

Flagstaff Leupp

Leupp Corner

Winslow

Munds Park

Mountainaire

Red Lake

Fraziers Well

Williams

Prescott

Parks

Moenkopi

Page

Tuba City

River

Colorado Havasu

Creek

Perennial streams from Arizona Department of Water Quality, 2015,

scale 1:100,000; Groundwater basin and sub-basin boundaries from

Arizona Department of Water Resources, 2008, scale 1:100,000;

Faults and folds from USGS SIR 2010–5180

4000

4400

3600

3200

3200

4800

5200

5600

6000

2800

2400

2000

6400

6800

7200

7600

8000

4000

5200

5600

4800

2800

2400

6400

4800

5200

4400

6800

4400

3600

4800

2400

2000

6400

5200

4000

6400

4400

4000

4400

4400

5200

4000

4800

3600

3600

4000

5200

3600

3600

3200

4800 4400

6000

6400

6800

5600

3600

4800

5200

5200

3200

EXPLANATION

Town or landmark

Post-2005 wells added for CPWAC Scenarios

Simulated incidental recharge at WWTFs

Simulated incidental recharge at golf course

Well included in NARGFM and CPWAC Scenarios

G Spring simulated using the MODFLOW Drain Package (DRN)

2006 water-level altitude in uppermost model layer, contour interval = 400 feet

Stream simulated using the MODFLOW Drain Package (DRN)

Stream simulated using the MODFLOW Stream Package (STR)

Perennial streams

Groundwater basin and subbasin boundary Coconino County boundary

0 5 10 20 30 40 MILES

0 10 20 40 60 80 KILOMETERS

Coconino Plateau Partnership area

County boundaries of the United States, USGS 2000 National Atlas, 1:2,000,000-scale resolution, 2002, USGS; 

Towns from USGS Geographic Names Information System, 1981. Coordinate System: NAD 1927 UTM Zone 

12N. Projection: Transverse Mercator. Datum: North American 1927. False Easting: 500,000.0000. False 

Northing: 0.0000. Central meridian: -111.0000. Scale factor: 0.9996. Latitude of origin: 0.0000. Units: meters

Figure 4. Map of the generalized groundwater-flow system initial conditions, including existing and projected withdrawal 

wells and the Arizona Department of Water Resources (ADWR) groundwater basins in the region of the Coconino Plateau 

Water Advisory Council (CPWAC) groundwater withdrawal scenarios. WWTF, waste-water treament facility.
12 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Table 1. Withdrawal wells that were not included in the original Northern Arizona Regional Groundwater Flow Model, installed after 

about 2005, and wells projected to be installed from 2006 through 2050. 

[Well locations are in North American Datum of 1927 coordinate system, in both Universal Transmercator (UTM) Zone 12 coordinates (meters) and geographic 

coordinates of latitude and longitude (degrees, minutes, and seconds)].

Well name UTM Easting UTM Northing Latitude Longitude Model layer

A-1 Mountain Sub-1 deep 432502 3895252 35° 11' 59.21" N 111° 44' 29.30" W 2

Anasazi Water Co. 398755 3981129 35° 58' 16.08" N 112° 07' 22.42" W 3

Bellmont Flagstaff Meadows 427261 3898447 35° 13' 41.60" N 111° 47' 57.57" W 2

Bellmont A-22-05 36CCC shallow 424956 3899850 35° 14' 26.53" N 111° 49' 29.20" W 3

Bellmont A-22-05 36CCC deep 424956 3899851 35° 14' 26.56" N 111° 49' 29.20" W 3

Bellmont A-21-06 06CBA 426781 3898834 35° 13' 54.04" N 111° 48' 16.68" W 3

Bodaway/Gap 464329 3983982 36° 00' 05.25" N 111° 23' 44.81" W 1

Bodaway/Gap 459482 3977509 35° 56' 34.47" N 111° 26' 57.22" W 1

Cameron 1, NTUA wells 460796 3976325 35° 55' 56.23" N 111° 26' 04.56" W 1

Cameron 2, BIA wells 459194 3968986 35° 51' 57.79" N 111° 27' 07.14" W 1

Canyon Mine 401100 3971500 35° 53' 04.46" N 112° 05' 44.49" W 3

Cedar Valley Water Co. (3 wells)1 462246 3893699 35° 11' 14.41" N 111° 24' 52.82" W 2

Flagstaff Local well field (Dogpound)445420 3893556 35° 11' 06.99" N 111° 35' 58.07" W 2

Flagstaff Local well field (I40tp) 443025 3894348 35° 11' 32.22" N 111° 37' 32.96" W 2

Flagstaff Local well field (Interchange)446253 3897563 35° 13' 17.22" N 111° 35' 26.07" W 2

Flagstaff Local well field (Shop) 448675 3898375 35° 13' 44.03" N 111° 33' 50.45" W 2

Flagstaff Local well field(Fort 

Tuthill)

437162 3889464 35° 08' 52.42" N 111° 41' 23.44" W 2

Flagstaff Local well 

field(Stonehouse)

436453 3894641 35° 11' 40.30" N 111° 41' 52.89" W 2

Flagstaff Local well field(Sinagua) 445267 3894261 35° 11' 29.84" N 111° 36' 04.28" W 2

Flagstaff Lake Mary well field 445670 3885700 35° 06' 52.02" N 111° 35' 46.32" W 2

Flagstaff Ranch Golf Course 18 435691 3892397 35° 10' 27.29" N 111° 42' 22.40" W 2

Flagstaff Ranch Golf Course 6 436093 3893000 35° 10' 46.96" N 111° 42' 06.67" W 2

Flagstaff Ranch Golf Course 7 435691 3893000 35° 10' 46.87" N 111° 42' 22.57" W 2

Flagstaff Ranch Golf Course 8b 435389 3892296 35° 10' 23.94" N 111° 42' 34.31" W 2

Flagstaff Red Gap Ranch A-20-13 

0 25CAA

507505 3884686 35° 06' 24.28" N 110° 55' 3.54" W 1

Flagstaff Red Gap Ranch A-20-13 

0 22CDB

504091 3885888 35° 07' 03.37" N 110° 57' 18.38" W 1

Flagstaff Red Gap Ranch A-20-14 

0 07CDB

508913 3889105 35° 08' 47.69" N 110° 54' 07.75" W 1

Flagstaff Red Gap Ranch A-20-13 

23DBB

506102 3886279 35° 07' 16.02" N 110° 55' 58.91" W 1

Flagstaff Red Gap Ranch A-20-13 

21CBA

502282 3886277 35° 07' 16.02" N 110° 58' 29.84" W 1

Flagstaff Red Gap Ranch A-20-13 

19DBC

499649 3886078 35° 07' 09.57" N 111° 00' 13.86" W 2

Flagstaff Red Gap Ranch A-20-13 

27ACC

504495 3884888 35° 06' 30.90" N 110° 57' 02.43" W 1

Flagstaff Red Gap Ranch A-20-14 

31CAA

509118 3883064 35° 05' 31.57" N 110° 53' 59.88" W 1

Flagstaff Red Gap Ranch A-20-13 

35AAA

506702 3883883 35° 05' 58.23" N 110° 55' 35.28" W 1
Withdrawal Scenarios 13

Table 1. Withdrawal wells that were not included in the original Northern Arizona Regional Groundwater Flow Model, installed after 

about 2005, and wells projected to be installed from 2006 through 2050.—Continued.

Well name UTM Easting UTM Northing Latitude Longitude Model layer

Flagstaff Red Gap Ranch A-19-14 

05ABD

511137 3882002 35° 04' 57.03" N 110° 52' 40.19" W 1

Flagstaff Red Gap Ranch A-20-

12.5 13ACB

497998 3886506 35° 07' 23.45" N 111° 01' 19.09" W 2

Flagstaff Red Gap Ranch A-20-13 

25ADA

508308 3885086 35° 06' 37.24" N 110° 54' 31.80" W 1

Flagstaff Red Gap Ranch A-20-13 

29ABB

501283 3885485 35° 06' 50.31" N 110° 59' 09.31" W 2

Fort Valley Deep wells (2 wells)1 434568 3902920 35° 16' 08.61" N 111° 43' 09.80" W 2

Fox Ranch 441607 3860447 34° 53' 11.43" N 111° 38' 20.45" W 2

Fox Ranch 438647 3858713 34° 52' 14.53" N 111° 40' 16.57" W 2

Gray Mountain 457438 3955623 35° 44' 43.78" N 111° 28' 14.59" W 1

Hopi Tribe at Moenkopi 481648 3996540 36° 06' 54.58" N 111° 12' 14.09" W 1

Howard Mesa 382088 3969930 35° 52' 05.93" N 112° 18' 21.76" W 1

Hualapai Tribe 277150 3931987 35° 30' 29.74" N 113° 27' 25.69" W 3

Leupp PW-1A 490306 3892082 35°10’ 24.31’’ N 111° 06’23.26’’ W 1

Leupp PW-2B 496398 3895436 35° 12’ 13.32” N 111° 02’ 22.45” W 1

Leupp PW-3 505425 3891201 35° 09’ 55.84’’ N 110° 56’25.55’’ W 1

Parks Deep well 413022 3901950 35° 15' 31.22" N 111° 57' 22.13" W 3

Patch Karr 397644 3946454 35° 39' 30.36" N 112° 07' 50.78" W 3

Supai Hilltop well 350319 4000488 36° 08' 21.74" N 112° 39' 48.92" W 3

Tusayan 1 398149 3980826 35° 58' 06.02" N 112° 07' 46.47" W 3

Tusayan 2 398345 3981395 35° 58' 24.55" N 112° 07' 38.91" W 3

Valle 1 396215 3945062 35° 38' 44.64" N 112° 08' 46.96" W 3

Valle 2 396014 3944861 35° 38' 38.04" N 112° 08' 54.85" W 3

Winona Casino 461850 3894911 35° 11' 53.70" N 111° 25' 08.68" W 2

Williams A-22-02 28BAD 391995 3902794 35° 15' 51.24" N 112° 11' 14.52" W 3

Bearizona A-22-22 06BBA 395002 3901505 35° 15' 10.55" N 112° 09' 14.94" W 3

1

More than a single well may be constructed in the vicinity of the site. The projected withdrawal rate from all wells, shown in appendixes 1–3, is simulated 

at a single well rather than multiple wells, which is unlikely to produce significantly different simulated results of regional water-level change or capture of 

nearby surface water features. 

wells and springs that flow from glacial outwash and volcanic 

rocks within the inner basin of San Francisco Mountain. The 

scenarios anticipate that future City of Flagstaff groundwater supplies will continue to be derived from the same areas, 

but augmented with new wells that tap the Coconino aquifer 

within city limits and at the Red Gap Ranch well field about 

10 miles west of Winslow. Total withdrawals by the City are 

currently capped at 9,913 ac-ft/yr from the existing sources 

based on an Adequate Water Supply Determination from 

ADWR (Erin Young, hydrologist, City of Flagstaff, written 

commun., 2014). Additional supplies from the new Red Gap 

well field will be capped at 8,000 ac-ft/yr by agreement with 

the Navajo Nation (Erin Young, hydrologist, City of Flagstaff, 

written commun., 2014). Maximum withdrawal rates for the 

City of Flagstaff for the scenarios are about 15,000 ac-ft/yr 

during 2051–2105, although as much as 16,500 ac-ft/yr may 

be withdrawn to meet the Designated Adequate Water Supply, 

a maximum annual withdrawal rate determined by the State of 

Arizona Department of Water Resources. Other communities 

near Flagstaff that use groundwater from the Coconino aquifer 

include Bellmont, Doney Park (including Timberline and 

Fernwood areas), Flagstaff Ranch, Forest Highlands, Kachina 

Village/Mountainaire, Winona, Coconino Estates, Munds 

Park, and Parks. Additional withdrawal wells are projected to 

be developed near many of these communities, at Fox Ranch 

south of Flagstaff, and near Cameron to the north of Flagstaff. 

The City of Williams is expected to develop new withdrawal 

wells in the Redwall-Muav aquifer. New withdrawal wells 

in the Redwall-Muav aquifer are also expected to be developed near the communities of Tusayan, Valle, Red Lake, and 

Gray Mountain. All nontribal water demands included in the 

CPWAC scenarios assume a 20 percent water conservation 
14 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

(Bureau of Reclamation, 2006) over conditions prior to 2010 

for the duration of the simulated period.

Many private wells withdraw small amounts of water 

for domestic and stock use throughout the scenario area. 

Most of these wells draw water from groundwater in volcanic rocks and other perched water-bearing zones. A few 

of these wells, however, do draw water from the Coconino 

aquifer. The withdrawal scenarios include estimates of 

future withdrawals for the private wells, but only at the 

wells existing in 2005. Total simulated withdrawal rates for 

these wells was about 500 ac-ft/yr during 2000–05 in the 

NARFGM model. The private well withdrawals are divided 

into three regions for the scenarios, including the corridor 

between Flagstaff and Williams, the corridor between Williams and Grand Canyon National Park, and all remaining 

areas. About 50 percent of these well withdrawals are in the 

Flagstaff to Williams corridor and about 25 percent of the 

withdrawals are in each of the other two areas.

Scenario 1

Scenario 1 assumes that all water demand will be met 

by continuing individual, tribal, and municipal groundwater 

development and that there will be no regional water project 

to bring a combination of surface-water and groundwater 

resources to meet water use demands in the CPWAC region 

by 2050. Scenario 1 has the most groundwater withdrawals of the three scenarios as withdrawals for each major 

groundwater user or group of users are projected to increase 

throughout the scenario. Total groundwater withdrawals 

from the Redwall-Muav and Coconino aquifers within the 

CPWAC region for scenario 1 increase from about 

10,800 ac-ft/yr during 2006–10 to about 25,300 ac-ft/yr 

beginning in 2050 (fig. 3A, appendix 1). Not included in the 

scenario are about 7,400 ac-ft/yr of groundwater withdrawals from the N aquifer for tribal use. 

Under this scenario the tribal demand for water will 

grow to a rate of 160 gallons per day per capita as tribal 

communities improve their infrastructure. Most of this new 

demand will be met by development of existing and new 

Coconino aquifer wells in the Leupp area. New Coconino 

aquifer wells will also be drilled in the area of Moenkopi. 

Other tribal demands for groundwater in the western part 

of the model domain for the Hualapai and Havasupai 

Tribes will be minor and developed from the RedwallMuav aquifer. Withdrawals from the Coconino aquifer near 

Cameron and Bodaway for the Navajo Tribe are projected 

to increase during 2010–50 from about 170 to 750 ac-ft/yr 

and 200 to 820 ac-ft/yr, respectively. Navajo Tribe withdrawals from the Coconino aquifer at and near Leupp are 

projected to increase from about 200 to 1,000 ac-ft/yr for 

the same period with the addition of several new wells. 

Withdrawals for the Hopi Tribe are projected to begin from 

the Coconino aquifer near Moenkopi before 2020 at a rate 

of about 30 ac-ft/yr and increase to 170 ac-ft/yr in 2050. 

Havasupai Tribe withdrawals from the Redwall-Muav aquifer 

near the western margin of the NARGFM region are projected 

to increase only slightly, from about 170 ac-ft/yr before 2010 

to 200 ac-ft/yr in 2050. Hualapai Tribe withdrawals from 

the Redwall-Muav aquifer near the western margin of the 

NARGFM region are projected to increase slightly to only 

about 10 ac-ft/yr by 2050.

Nontribal demand for water will occur mostly in Flagstaff 

and in surrounding areas including the Williams, Valle, and 

Tusayan areas, the region between Winslow and Leupp, and 

as far south as Munds Park (fig. 1). The City of Flagstaff will 

continue to develop new wells in the inner city area, including 

the Local well field, and at Red Gap Ranch, which could be 

supplying water to the city by 2020. Groundwater development for projected nontribal water demands in the Williams, 

Valle, and Tusayan areas will come from the Redwall-Muav 

aquifer. The City of Williams is capped at development of 

700 ac-ft/yr from its existing wells in the Redwall-Muav 

aquifer south of Williams by an agreement with ADWR (Dennis Wells, Williams City Manager, oral commun., 2007). That 

limit is projected to be nearly attained at 675 ac-ft/yr by about 

2050. Additional demands on the Redwall-Muav aquifer in 

the region between Williams and Grand Canyon are dependent on if, and how, Grand Canyon National Park resolves its 

maintenance and (or) replacement issues with the trans-canyon 

pipeline that delivers water from Roaring Springs on the north 

rim to the south rim, and future development at Tusayan and 

Valle.

Most of the projected increases in nontribal withdrawals 

occur in the vicinity of Flagstaff and nearby communities. City 

of Flagstaff withdrawals, including withdrawals at Red Gap 

Ranch, increase from about 7,000 ac-ft/yr before 2010 to about 

15,000 ac-ft/yr in 2050. Flagstaff withdrawals are distributed 

among the existing wells at the Woody Mountain, Lake Mary, 

and Local well fields, the inner basin area of San Francisco 

Mountain, and new wells at Red Gap Ranch. Reduced withdrawals at the Lake Mary well field of about 900 ac-ft/yr in 

2010 are partly replaced by increases in withdrawals from the 

Local well field. Increases in City of Flagstaff withdrawals 

after 2019 will be sourced from wells at the Woody Mountain, 

Local, and Red Gap Ranch well fields, including increases of 

about 1,300, 2,300, and 4,300 ac-ft/yr, respectively, by 2050. 

Withdrawals for several other communities near Flagstaff are 

projected to increase from about 2,100 ac-ft/yr before 2010 to 

about 3,800 ac-ft/yr in 2050. Withdrawals from stock, domestic, and small industrial wells are projected to increase from 

about 500 to 1,600 ac-ft/yr by 2050, with about 50 percent 

of the increase occurring in the region between Flagstaff and 

Williams.

Scenario 2

Scenario 2 assumes that the proposed Western Navajo 

Pipeline will provide a source of surface water from Lake 

Powell to the communities of Cameron, Tuba City, and 
Withdrawal Scenarios 15

Moenkopi, and all nontribal water demands will continue to be 

met by groundwater development. Under this scenario, there 

will be limited groundwater development of the Coconino 

aquifer in the Leupp area to meet projected local demands. 

Projected nontribal demands for water will be met by development of groundwater from the Coconino aquifer and the 

Redwall-Muav aquifer as described in scenario 1. 

Total groundwater withdrawals from the Redwall-Muav 

and Coconino aquifers within the CPWAC region for scenario 2 increase from about 10,800 ac-ft/yr during 2006–10 to 

about 23,400 ac-ft/yr during 2050–2105 (fig. 3B, appendix 2). 

Withdrawals for major groundwater users or group of users 

increase throughout the scenario with the exception of use by 

the Navajo and Hopi Tribes, which increase at much reduced 

rates in comparison to scenario 1 because of the elimination 

of groundwater withdrawals for tribal use from the Coconino 

aquifer near Cameron and Moenkopi. Similar to scenario 

1, most increases in groundwater withdrawals for scenario 

2 result from increases in Flagstaff and nearby community 

withdrawals. Withdrawals from stock, domestic, and small 

industrial wells are projected to increase to 1,600 ac-ft/yr, as 

was assumed for scenario 1. Overall groundwater withdrawals 

for scenario 2 during 2050–2105 are about 1,900 ac-ft/yr less 

than those in scenario 1.

Scenario 3

Scenario 3 assumes that there will be a partnership 

between the tribal and nontribal interests on the Coconino 

Plateau that make it possible to extend a part of the proposed 

Western Navajo Pipeline onto the Coconino Plateau to supply 

projected unmet demands for water in this area by 2050. As 

part of an appraisal study by the Bureau of Reclamation for 

the CPWAC, the projected unmet demands for nontribal water 

on the Coconino Plateau were about 15,800 ac-ft/yr (Bureau 

of Reclamation, 2006). All other nontribal water demands 

will continue to be met by groundwater development in the 

Coconino and Redwall-Muav aquifers.

Total groundwater withdrawals from the Redwall-Muav 

and Coconino aquifers within the CPWAC region for scenario 

3 increase from about 10,800 ac-ft/yr during 2006–09 to about 

20,900 ac-ft/yr during 2050–2105 (fig. 3C, appendix 3). 

Withdrawals for major groundwater users or group of users 

increase throughout the scenario, but at rates that are much 

reduced in comparison to scenario 1. Similar to scenarios 

1 and 2, most of increases in groundwater withdrawals for 

scenario 3 result from increases in Flagstaff and nearby communities. The reduced rates of groundwater withdrawals to 

nontribal users would be offset by imported surface water. All 

of the reduced withdrawals relative to scenario 2 are because 

of reduced groundwater withdrawals for the Cities of Flagstaff 

and Williams after 2019. City of Flagstaff withdrawals are 

reduced over scenarios 1 and 2 by maintaining withdrawal 

rates at the Local well field at 2020 rates of 2,500 ac-ft/yr 

during 2030–2105 rather than the greater rates for scenarios 1 

and 2. City of Williams withdrawals are eliminated after 2019. 

Groundwater withdrawals by all private domestic, stock, and 

industrial wells are unchanged from scenarios 1 and 2. Overall 

groundwater withdrawals for scenario 3 during 2050 through 

2105 are about 4,300 ac-ft/yr less than those in scenario 1.

Additional Scenario Assumptions

A few additional assumptions were required to complete 

each of the groundwater withdrawal scenarios. Assumptions were applied regarding distributions of withdrawals by 

small private and stock wells and wells not considered in the 

scenarios (outside of the CPWAC area of concern); rates of 

natural, artificial, and incidental recharge; and how to treat 

loss of withdrawals that occur as a result of model cells that 

dry during the simulations. Withdrawals from aquifers not 

included in the NARGFM were not considered in the scenarios. This exclusion primarily included withdrawals from 

the Navajo aquifer and overlying aquifers in the Black Mesa 

area. Wells that withdraw water from local perched aquifers, 

such as in volcanic rocks that overlie the regional Coconino 

and Redwall-Muav aquifers, were not explicitly simulated 

in NARGFM. However, these local shallow aquifers were 

implicitly simulated by assuming discharge from them likely 

flows into the underlying regional aquifers, and that withdrawals from the shallow aquifers remove water that would otherwise recharge the regional aquifers. Withdrawals from shallow 

perched aquifers that overlie and discharge to the regional 

aquifers were therefore included in the scenarios as withdrawals from the regional aquifers.

Small Private and Stock Well Withdrawals

Withdrawals from most small private and stock wells 

were assumed to vary in the future according to the scenario withdrawal category “Other domestic, stock and small 

industrial groundwater” (appendixes 1–3). Several additional 

tribal and private wells were anticipated by CPWAC to be 

added to this withdrawal category after 2005 (table 1) and 

were assigned the withdrawal rates for the category “Other 

domestic, stock and small industrial groundwater”. Additional private wells were included in the simulations for the 

Canyon Mine located between Valle and Tusayan (fig. 4) and 

Bearizona Wildlife Park near Williams (appendixes 1–3). 

The uses of an estimated 44 ac-ft of groundwater withdrawals from the Redwall-Muav aquifer at the Canyon Mine are 

for the construction of the mine shaft during 2013–16, mining 

during 2016–22, and reclamation activities during 2023–25. 

Groundwater use at this site is scheduled to return to zero after 

2029. Annual groundwater withdrawals at Bearizona Wildlife 

Park are estimated as about 120 ac-ft/yr beginning with a well 

drilled in 2015.
16 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Natural Recharge Rates

Natural recharge rates for the three simulated groundwater withdrawal scenarios are assumed to occur at a constant rate that is equivalent to average-annual rates of natural 

recharge simulated in NARGFM. Average recharge rates 

applied to NARGFM were derived from the modified Basin 

Characterization Model (BCM; Flint and Flint, 2008), which 

estimates direct monthly recharge that is calculated as the 

remainder of precipitation after accounting for runoff, evaporation, vegetation requirements, and retention of moisture by 

soils. The BCM estimates used in NARGFM were modified 

to include additional recharge through ephemeral channels 

in alluvial basins that are outside of the area of the CPWAC 

scenarios. No modifications of BCM recharge estimates were 

made in the area of the CPWAC scenarios.

Incidental Recharge Rates

Additional assumptions were made regarding projected 

rates of incidental recharge within and outside of the CPWAC 

scenario region. Incidental recharge occurs as a result of 

excess irrigation of golf courses and agricultural fields, and 

effluent discharged from waste-water treatment facilities 

(WWTF). This assumption is consistent with the assumed 

groundwater withdrawal rates outside of the CPWAC area 

that were previously discussed. For all sources of incidental 

recharge outside of the CPWAC scenario region, simulated 

rates of incidental recharge for the period 2000–05 were 

projected to remain at 2000–05 rates throughout the period 

of the scenario simulations. Incidental recharge from excess 

irrigation of golf courses and agriculture within the CPWAC 

scenario area was assumed to occur during the scenarios 

at the same rate and locations that it occurred during the 

2000–05 NARGFM simulation period. Incidental recharge 

from discharge of effluent at 13 WWTFs were simulated in the 

scenarios (table 2). Six of the WWTFs were simulated in the 

original NARGFM including Munds Park, Kachina Village, 

City of Williams, Supai Village, and two City of Flagstaff 

facilities—Rio de Flag and Wildcat Hill (table 2). For the 

scenario simulations, incidental recharge from an additional 

7 WWTFs were included in the scenario simulations including Forest Highland, Flagstaff Ranch, Flagstaff Meadows 

at Bellmont, Cameron, Leupp, Tusayan, and Grand Canyon 

Village. These additional WWTFs were not included in the 

original NARGFM simulations because either the estimated 

incidental recharge rate for each facility was estimated at less 

than 50 ac-ft/yr or the facilities did not exist before 2005. 

Other WWTFs within the CPWAC scenario area at Tuba City 

and Moenkopi were not simulated because effluent from these 

facilities is discharged to channels that flow over outcrops of 

Mesozoic aquifers and confining units that are hydraulically 

separated from the simulated aquifers and greatly limit any 

recharge to the simulated aquifers.

Incidental recharge from the WWTFs was assumed to 

remain as a constant percentage of water demand for each 

community throughout the simulation period for each scenario (table 2). Water demand and incidental recharge at two 

facilities, Grand Canyon Village and Forest Highlands, was 

assumed to remain unchanged through the scenario period. 

Demand and incidental recharge for the other 11 facilities was 

assumed to increase with projected demand. Total estimated 

incidental recharge of wastewater effluent increases from 

about 5,700 ac-ft/yr during 2006–09 to about 13,000 ac-ft/yr 

during 2050–2105. Most incidental recharge from wastewater 

effluent is estimated to occur near the two City of Flagstaff 

facilities, Rio De Flag and Wildcat Hill, which account for 

about 80 percent of the total estimated effluent recharge 

within the CPWAC area throughout the scenario simulation 

period. Estimated incidental recharge near the City of Flagstaff 

facilities increases from about 4,900 ac-ft/yr during 2006–09 

to about 10,700 ac-ft/yr during 2050–2105. In comparison, 

total estimated incidental recharge near the other 11 facilities 

increases from about 900 ac-ft/yr to about 2,400 ac-ft/yr over 

the same period. 

Drying of Model Cells During the Scenario 

Simulations

Drying of model cells that include well withdrawals 

outside of the scenario area was allowed to occur, resulting 

in some areas where much of the withdrawals were eliminated during the scenarios. Fortunately, the withdrawal losses 

did not cause variations in the simulation results within the 

area of CPWAC scenarios because the losses were outside of 

the CPWAC area and common in rate and location for each 

scenario.

Distributions of some withdrawals within the scenario 

area were modified from the pre-2006 simulation for the 

purpose of preventing drying of the pumped model cell and 

allowing retention of the projected withdrawals throughout 

the period of the simulation, including the locations of withdrawals at several wells near the Woody Mountain and Lake 

Mary well fields. Modifications included redistribution of the 

withdrawals to include deeper layers, and lateral translation 

of wells to spread the collective cone of depression resulting 

from a concentrated area of well withdrawals. Withdrawals from all wells at the Woody Mountain well field were 

expanded from only model layer 2 (lower part of the Coconino 

aquifer) to include model layer 3 (Redwall-Muav aquifer). 

Well locations at the Woody Mountain well field were moved 

as much as 1.5 miles laterally to reduce the concentration of 

pumping in single model cells. Withdrawals from two wells 

at the Lake Mary well field were expanded from only model 

layer 2 to include model layer 3. Withdrawals from several 

wells outside of the CPWAC scenario area near Holbrook 

were also relocated to maintain withdrawal rates near the area 

of CPWAC concern; some were moved as much as 1 mile 

laterally to reduce the concentration of pumping. Withdrawal 

distributions at a few wells near Holbrook were expanded 

from only model layer 1 to include model layers 2 and 3. As 
Withdrawal Scenarios 17

Table 2. Projected and simulated incidental recharge rates at waste-water treament facilities in the Coconino Plateau Water Advisory Council Scenario region for three groundwater withdrawal scenarios.[Values are in acre-feet per year]

Waste-water treatment facility1 Community served1

Simulated incidental recharge 

rate, 2000-2005

Incidental 

recharge rate 

as a percent of 

groundwater 

demand served3

Simulated incidental recharge rate

scenarios 1, 2, and 3

2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105

Munds Park Waste-Water Treatment 

Plant

Munds Park 80 24 24 52 80 108 137 165

Kachina Village Waste-Water Treatment 

Facility

Kachina Village 213 62 110 220 228 235 243 249

Rio De Flag Waste-Water Treatment 

Plant

Flagstaff 5,028 50 3,894 4,650 5,306 6,225 7,429 8,573

Wildcat Hill Waste-Water Treatment 

Plant

Flagstaff 1,239 12 959 1,145 1,307 1,533 1,830 2,112

City of Williams Waste-Water Treatment 

Plant

Williams 455 49 181 203 226 248 271 292

Supai Village Sewer System Supai Village 45 26 45 46 46 53 53 53Forest Highlands Waste-Water Treatment Plant Forest Highlands NA2 13 72 72 72 72 72 72Flagstaff Ranch Waste-Water Treatment 

Plant

Flagstaff Ranch NA2 64 64 80 80 72 64 64

Flagstaff Meadows at Bellmont Flagstaff Meadows NA2 80 40 68 72 80 100 120Cameron Waste-Water Treatment Plant Cameron NA2 18 35 41 66 87 113 146Leupp Waste-Water Treatment Plant Leupp NA2 50 100 388 510 632 753 875Tusayan Waste-Water Treatment Plant Tusayan NA2 32 24 72 88 104 121 137Grand Canyon South Rim Waste-Water 

Treatment Plant

Grand Canyon 

South Rim

NA2 0 186 186 186 186 186 186

Total simulated incidental recharge from waste-water treatment facilities 5,734 7,224 8,267 9,634 11,370 13,042

1Additional waste-water treament facilities in Coconino County were not simulated including Moenkopi and Tuba City. Effluent from these facilties is discharged to stream channels that cross the Chinle 

and Moenkopi Formations, which are assumed an impermeable upper boundary and confining bed for the Northern Arizona Regional Groundwater Flow Model (NARGFM).

2Incidental recharge from waste-water effluent was not included in the original NARGFM for these facilities.3Incidental recharge rate as a percent of groundwater demand served is calculated for each facility based on NARGFM simulated rates of recharge and withdrawals during 2000 to 2005 or the most recent 

reported facility discharge and withdrawals for facilities that were not simulated in the original NARGFM.
18 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

a result of the modified distribution of withdrawals, no cells 

went dry and no withdrawals were lost from the simulation in 

the area of interest. 

Simulated Effects of Withdrawal 

Scenarios

The simulated effects of the three groundwater withdrawal scenarios are superimposed on the effects of previously 

simulated changes to the groundwater-flow system that have 

resulted from variations in groundwater withdrawals and artificial and incidental recharge in the original NARGFM. Effects 

of the variations include changes in water-levels in wells, 

groundwater storage, discharge to streams and springs, and 

ET by plants that use groundwater. Variations in recharge rates 

were also simulated in the published version of NARGFM 

(Pool and others, 2011). However, past and possible future 

recharge variations were not simulated for this analysis 

because those variations result in much greater change than 

the variations in the scenarios. A constant rate of average 

annual-recharge, equivalent to the average recharge during 

1940–2005, was simulated for the scenarios. Eliminating 

recharge variations allows the analysis to focus on the effects 

of only past variations in withdrawals and incidental recharge 

and the scenario variations in withdrawals.

Simulation of the scenarios were completed for the period 

2006 through 2105 using 10 time steps within 6 stress periods. Pre-2050 stress periods included the 5-year period 2006 

through 2009 followed by periods of decade length during 

2010 through 2049. Simulation of conditions through 2105 

result in only a part of the changes that will occur before a new 

steady-state groundwater-flow system is attained in the future. 

If no additional simulated changes in groundwater withdrawal 

and recharge were too occur after 2105, the groundwater-flow 

system would eventually reach a new steady-state condition 

of reduced but constant storage, and reduced discharge to 

streams, springs, and ET. However, changes that may occur 

after 2105 are not addressed in this analysis.

Initial Conditions for the Scenarios

The groundwater-flow system simulated by a modified 

version of the NARGFM at the beginning of 2006 represents 

initial conditions for simulations of the three withdrawal 

scenarios (fig. 3). Specifically, the simulated hydraulic heads 

throughout the model at the end of 2005 are used as the 

initial hydraulic heads for the scenarios. Modifications to the 

published NARGFM included simulation of average-annual 

recharge rates rather than variable recharge rates, and redistribution of withdrawals at the Woody Mountain well field across 

a slightly greater area for the purpose of maintaining saturated 

conditions in the uppermost model layer through the scenario 

period to 2105. The groundwater-flow system at the beginning 

of 2006 was in a state of change resulting from previous variations in groundwater withdrawals and artificial and incidental 

recharge. While change had occurred during the simulation 

of conditions during 1910–2005, the beginning and ending 

groundwater-flow systems were largely similar. Groundwater in the NARGFM area flows from areas of high rates of 

recharge in the high altitude areas of the White Mountains, 

Mogollon Rim, San Francisco Mountain, Defiance Uplift, and 

Kaibab Plateau toward the primary discharge areas along the 

major perennial streams including the Colorado, Little Colorado, Verde, and Salt Rivers. Groundwater also discharged to 

other perennial streams including Clear and Chevelon Creeks 

near the eastern border of Coconino County, Oak and Sycamore Creeks south of Flagstaff, streams and many springs near 

the Grand Canyon, and streams at the western extent of the 

NARGFM. Evapotranspiration of groundwater was minor in 

comparison to other water-budget components in the CPWAC 

region. Local cones of depression were established before 

2006 in areas of concentrated groundwater withdrawal including the Woody Mountain and Lake Mary wells fields near 

Flagstaff.

Simulated groundwater budgets at the end of 2005 document the effect of simulated changes in the groundwater-flow 

system (table 3). Groundwater was being withdrawn from 

storage in all simulated groundwater basins in the NARGFM 

at the end of 2005. Rates of storage loss in basins that are 

partly within the CPWAC area include 85,000 ac-ft/yr in the 

Coconino Plateau basin, 54,000 ac-ft/yr in the Little Colorado 

River Plateau basin, and 39,000 ac-ft/yr in the Verde Valley 

subbasin. The storage loss occurred as a result of the effects of 

groundwater withdrawals and variations in artificial and incidental recharge before 2006. Storage losses that occurred in 

2005 indicate that losses in groundwater discharge to streams 

and springs will occur after 2005 even if no further changes in 

withdrawals and recharge occur. These future declines in rates 

of net discharge to streams and springs in the NARGFM will 

be less than or equivalent to the simulated rate of storage loss 

in 2005. Eventually, given no future changes in withdrawals 

and recharge, a new steady-state groundwater-flow system will 

result and all of the rates of loss in storage will be replaced by 

reduced rates of discharge to streams and springs.

Rates of discharge to streams, springs, and ET that were 

simulated during 2005 will likely decrease during the simulated future withdrawal scenarios as a result of past withdrawals throughout the NARGFM. Reduced streamflow derived 

from groundwater may also result in greater infiltration of 

runoff; however, the NARGFM simulates only groundwater processes. Changes in discharge to streams and springs 

will occur within the groundwater basins that lie nearest to 

Coconino County including the Coconino Plateau and Little 

Colorado River Plateau basins and the Verde Valley subbasin. 

Simulated groundwater discharge in these basins occurs to 

the Blue Springs and the Lower Little Colorado River, Clear 

Creek, Chevelon Creek, the Colorado River, numerous springs 

above the Colorado River, Havasu Creek, and the Verde River 

and tributary streams including those nearest to the CPWAC 
Simulated Effects of Withdrawal Scenarios 19

Table 3. Simulated groundwater-flow budgets at the end of 2005 for selected regions of the Northern Arizona Regional Groundwater-Flow Model from Pool and others (2011).[Values are in acre-feet per year except for cumulative values, which are in acre-feet. N/A, not applicable]

Groundwater Basin Upper Agua Fria

Verde River Basin groundwater-flow system

Little Chino

Little Chino and 

Upper Agua Fria 

sub-basins

Big Chino Big and Little Chino

Verde Valley 

sub-basin above 

the streamflowgaging station near 

Clarkdale

Verde Valley sub-basin 

between the streamflowgaging stations near Clarkdale and near Camp 

Verde

Verde 

Valley 

Verde 

Canyon

Arizona Department of Water Resources basin type sub-basin sub-basin

Prescott Active 

Management 

Area

sub-basin sub-basins part of sub-basin part of sub-basin sub-basin sub-basin

Groundwater-budget componentInflow

Natural recharge 1,300 1,800 3,100 31,200 33,000 22,500 46,100 68,600 26,400

Recharge from infiltration of streamflow derived 

from base flow1a

N/A 700 700 1,900 2,600 13,800 24,700 38,500 1,800

Incidental recharge1b 2,300 7,000 9,200 4,200 11,200 0 1,600 1,600 0

Groundwater inflow from adjacent areas1c 1,000 1,500 1,800 3,500 5,100 8,800 1,700 8,000 33,100

Total Inflow1d 4,600 11,000 14,800 40,800 51,800 45,100 74,000 116,700 61,300

Outflow

Groundwater discharge to streams (base flow)1e N/A 1,800 1,800 18,100 19,900 36,100 62,200 98,400 62,800

Discharge to streams and springs simulated as 

drains (base flow)1f

1,000 0 1,000 0 0 0 0 0 500

Evapotranspiration by phreatophytes1g 100 100 200 1,900 2,000 2,600 9,300 11,900 N/A

Groundwater withdrawals 6,400 17,800 24,200 11,200 28,900 200 2,010 19,500 1,600

Groundwater outflow to adjacent areas1h 0 2,600 1,800 26,900 29,500 14,900 13,400 25,800 11,400

Total Outflow1i 7,500 22,200 28,900 58,100 80,400 53,900 104,200 155,600 76,400

Net groundwater flow to (-) and from (+) 

adjacent basins1j

1,000 1,0002 0 23,4003 24,4003 -6,000 -11,800 -17,800 21,700

Net streamflow1k N/A 1,100 1,100 16,200 17,300 22,300 37,6004 59,9004 61,000

Net rate of groundwater storage change -2,900 -11,200 -14,100 -17,400 -28,600 -8,800 -30,200 -39,000 -15,200

Cumulative groundwater storage change since 

predevelopment

-117,100 -586,500 -703,600 116,700 -469,800 242,200 295,500 537,700 201,200
20 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Table 3. Simulated groundwater-flow budgets at the end of 2005 for selected regions of the Northern Arizona Regional Groundwater-Flow Model from Pool and others (2011).—Continued.

Groundwater Basin

Colorado River Basin groundwater-flow system Western basins groundwater-flow system Salt River sub-basins groundwater-flow system

Little Colorado Coconino Plateau Peach Springs Kanab Plateau and adjacent 

areas

Burro 

Creek

Fort Rock 

(Trout 

Creek)

Truxton Wash Western basins1g Tonto Creek Salt River Lakes Salt River above the streamflow-gaging station at Roosevelt

Arizona Department of Water Resources basin type basin basin

Part of basin that lies 

outside of Truxton 

Wash watershed

several basins 

north of the 

Colorado River

sub-basin sub-basin

Parts of Peach 

Springs basin 

and Wikieup 

sub-basin

simulated 

groundwater basin1l basin basin

Salt River Canyon, 

Black River, and 

White River subbasins

Groundwater-budget componentInflow

Natural recharge 154,900 113,900 5,100 75,200 13,400 14,600 3,300 31,400 39,700 28,300 133,300

Recharge from infiltration of streamflow 

derived from base flow1a

13,100 300 N/A N/A N/A N/A N/A N/A N/A N/A N/A

Incidental recharge1b 49,800 500 0 0 0 0 100 100 1,900 1,300 1,200

Groundwater inflow from adjacent areas1c 2,600 190,400 5,400 38,100 6,200 1,500 1,700 9,400 26,400 1,900 10,800

Total Inflow1d 220,300 305,100 10,500 113,300 19,700 16,100 5,100 40,900 67,900 31,500 145,200

Outflow

Groundwater discharge to streams (base 

flow)1e

13,100 173,000 N/A N/A N/A N/A N/A N/A N/A N/A N/A

Discharge to streams and springs simulated 

as drains (base flow)1f

300 160,700 7,600 135,900 25,800 13,300 2,900 42,000 84,100 43,200 203,200

Evapotranspiration by phreatophytes1g 0 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

Groundwater withdrawals 81,700 800 0 0 400 0 100 500 1,100 1,300 600

Groundwater outflow to adjacent areas1h 210,400 25,100 4,900 9,000 0 9,700 3,300 13,000 2,700 200 0

Total Outflow1i 305,600 359,500 12,400 145,000 26,100 23,100 6,300 55,500 87,900 44,700 203,700

Net groundwater flow to (-) and from (+) 

adjacent basins1j

-207,900 165,300 600 29,100 6,200 -8,200 -1,600 -3,600 23,600 1,600 10,800

Net streamflow1k 0 172,700 N/A N/A N/A N/A N/A N/A N/A N/A N/A

Net rate of groundwater storage change -85,000 -54,000 -1,900 -31,800 -6,500 -6,900 -1,200 -14,600 -20,100 -13,200 -58,400

Cumulative groundwater storage change 

since predevelopment

669,500 1,275,100 70,800 1,021,000 130,600 156,700 37,900 325,200 322,400 326,600 1,205,600

1a-Includes the total of simulated streamflow infiltration; all of which is derived from discharge of groundwater to streams 

(simulated using the MODFLOW Streams Package (STR)) within the groundwater basin and in upgradient groundwater basins.

1b-Includes recharge resulting from excess applied irrigation water derived from surface water and groundwater supplies, 

discharge from waste-water treatment facilites, and golf courses.

1c- Includes components of groundwater inflow from multiple adjacent basins and sub-basins.1d-Represents the sum of inflow components including groundwater flow from adjacent basins and reinfiltration and 

recharge of groundwater discharge to streams in the groundwater basin.

1e-Includes only discharge to streams simulated using the MODFLOW Streams Package (STR).1f- Streams and springs simulated using the MODFLOW Drain Package (DRN).1g- Evapotranspiration was simulated in only the Verde River Basin above the streamflow-gaging station near Camp 

Verde and in the Little Colorado River Basin.

1h- Includes components of groundwater outflow to multiple adjacent basins and sub-basins.

1i- Calculated as Total Inlow minus Total Outflow. Multiple areas of groundwater inflow and outflow may 

occur for any basin.

1j- Calculated as Groundwater Infow minus Groundwater Outflow.1k- Calculated as Recharge from infiltration of streamflow derived from base flow minus Groundwater discharge to streams. Both components are simulated using the Streams Package (STR).1l- Includes the sum of groundwater budget components for the Burro Creek and Fort Rock sub-basins and the 

parts of the Peach Springs Basin and Wikieup sub-basin within the Truxton Wash watershed. 

2- Includes groundwater outflow of about 2,100 ac-ft per yr to the Big Chino sub-basin and inflow from portions of the Big Chino (about 1,000 ac-ft per yr) and Upper Agua Fria sub-basins.3- Includes the balance of outflow of groundwater to adjacent basins and inflow from adjacent basins, primarily 

from the Little Chino sub-basin.

4- Does not include diversion of 34,600 acre-ft per year of base flow that is transpired by crops.
Simulated Effects of Withdrawal Scenarios 21

region, Sycamore Creek, Oak Creek, Beaver Creek, and West 

Clear Creek. Discharge to streams in the Little Colorado River 

Plateau basin—13,100 ac-ft/yr in 2005—primarily occurs 

along Clear, Chevelon, and Silver Creeks and along the upper 

reaches of the Little Colorado River. The discharge also 

infiltrates and recharges in downstream reaches of the stream 

network. As a result, both discharge and recharge along the 

streams in the Little Colorado River Plateau basin will change 

at equivalent rates during scenario simulations.

Scenario Simulation Results

Scenarios 1, 2, and 3 each result in a different set of simulated hydrologic changes within the modeled area. Change 

simulated by scenario 1 represents change that will occur 

due to projected increased demand for groundwater without 

management decisions to limit groundwater withdrawals, 

using water imported to the area through a proposed pipeline. 

Change simulated by scenarios 2 and 3 represents change 

resulting from the proposed pipeline and less groundwater 

withdrawals than simulated by scenario 1. Scenario 2 includes 

a limited extent of the pipeline to the Cameron area. Scenario 

3 represents the greatest pipeline extent, maximum importation of water to the greatest area, and the least amount of 

simulated groundwater withdrawals. For this analysis of future 

water use scenarios developed by the CPWAC, comparisons of 

hydrologic changes resulting from the scenarios are made for 

only the region in and near the CPWAC scenario area. Differences in simulated water-level change in the primary aquifers 

are compared for conditions simulated at the end of 2105 for 

each scenario. Simulated changes in groundwater discharge 

to major perennial streams and springs resulting from each 

scenario are also discussed. The major streams and springs 

include Havasu Creek, the Colorado River, four simulated 

springs on the south rim of Grand Canyon, the lower reach 

of the Little Colorado River below Cameron including Blue 

Springs, Chevelon Creek, Clear Creek, Oak Creek, and the 

upper Verde River above the streamflow gaging station near 

Clarkdale.

Simulated Changes in Water Levels

Simulated water-level change during 2006–2105 in the 

CPWAC region is discussed for scenarios 1, 2, and 3. Scenario 

1 water-level declines are the greatest of the three scenarios 

because it includes the assumption that no water would be 

imported to the region and groundwater withdrawals would 

continue to supply a large portion of the water demand for the 

area. As a result, scenario 1 includes the greatest increase in 

groundwater withdrawals. Scenario 1 water-level changes are 

treated as a baseline for comparison with water-level change 

resulting from scenarios 2 and 3, which include imported surface water and reduced groundwater withdrawals in the Cameron and Moenkopi areas for scenario 2, and extension of the 

imported surface water to the Flagstaff and Williams areas and 

associated reduced groundwater withdrawals for scenario 3. 

Scenario 1

Simulated water-level change is dominated by declines 

of 1 to 5 ft across most of the CPWAC and adjacent areas 

for scenario 1 during 2006–2105 (fig. 5). Most of the larger 

changes occur in areas near major withdrawal wells and areas 

of incidental recharge at major wastewater treatment plants and 

facilities. In 2105, the simulation predicts water-level declines 

of more than 100 ft near the Woody Mountain and Lake Mary 

well fields and the towns of Tusayan and Parks. Maximum 

declines near Williams and Moenkopi are about 50 ft. Declines 

of 10 to 50 ft are simulated near other major withdrawal wells 

near Sedona, Munds Park, Winona, Leupp, and Red Gap 

Ranch. Water-level rises of more than 100 ft are simulated near 

the City of Flagstaff Waste-Water Treatment Plants at Wildcat 

Hill, Rio De Flag, and Grand Canyon Village. Water-level 

rises of 1 to 10 ft simulated near Clear and Chevelon Creeks 

result from pre-2006 changes in withdrawals or incidental 

recharge outside of the scenario area that were continued into 

the scenario period. Apparent water-level recovery resulted in 

resaturation of model cells during the scenario simulation in 

several areas including south of Williams, northwest of Tuba 

City, small areas near Clear and Chevelon Creeks, and small 

areas in Verde Valley. Most of the resaturated areas are at the 

margins of model layers where the layer is thinnest and susceptible to dewatering. Resaturation is caused by changes in well 

withdrawals and incidental recharge in the scenario relative to 

the original NARGFM at the end of 2005.

Scenarios 2 and 3 

Importing water and eliminating major withdrawal wells 

after 2009 in the Cameron area resulted in less water-level 

decline and slightly higher water levels in scenario 2 compared 

to scenario 1 from 2006 to 2105 (fig. 6A). Less water-level 

decline was simulated and water levels for Scenario 2 were 

slightly higher than in Scenario 1 across nearly all of the scenario region. In the Cameron areas area, scenario 2 water levels 

were 1 to 5 ft higher than in scenario 1. Near Moenkopi, a 

small area of water levels are as much as 10 ft higher due to the 

elimination of a proposed withdrawal well that was simulated 

in scenario 1.

The effects of importing water beyond the Cameron area 

to Flagstaff and Williams and reducing groundwater withdrawals in the area during 2006 to 2105 are shown on a map of the 

difference in water-level change simulated by scenario 3 in 

comparison to scenario 1 (fig. 6B). Results near Cameron and 

Moenkopi are similar to scenario 2 because well withdrawals 

in those areas were similar for both scenarios 2 and 3 and less 

than in scenario 1. Water levels for scenario 3 are about 1 to 

5 ft higher in comparison to scenario 1 across about one-half 

of the Coconino Plateau between Williams and the Colorado 

River. Water levels simulated near withdrawal wells in the 
22 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Page

Valle

Leupp

Parks Winona

Sedona

Tusayan

Cameron

Winslow

Red Lake

Williams

Tuba City

Flagstaff

Grand Canyon

Village

Supai

Prescott

Munds

Park

Moenkopi

Blue Springs

Little

Colorado

Clear

Creek

Chevelon

Creek

Verde River

Creek

Creek Beaver

River

Colorado

River

Clear Creek

West

Creek

Burro

Creek

Trout

Oak

Creek

Havasu

Lake Mary

well field

San Francisco

Mountain

Woody

Mountain

well field

Coconino

Plateau

basin

Little Colorado

River Plateau

basin

Verde Valley

sub-basin

Big Chino

sub-basin

Little

Chino

sub-basin

Fort Rock

sub-basin

Peach

Springs

sub-basin

Kaibab

Plateau

Black

Mesa

 Complex

Mogollon Rim

Red Gap

Ranch

well field

Flagstaff

Local

well field

113° 112° 111°

37°

36°

35°

Perennial streams from Arizona Department of Water Quality, 2015,

scale 1:100,000

EXPLANATION

Town or landmark

Perennial streams

Simulated stream

Groundwater basin and subbasin boundary

Coconino County boundary

Model layer 1 active extent

Model layer 2 active extent

Model layer 3 active extent

Layer

resaturation

Layer

resaturation

Layer

resaturation

5 10 20 30 40 MILES

0 10 20 40 60 80 KILOMETERS

0

Simulated water-level change

Feet

<100

-50– -100

-10– -50

-5– -10

-1– -5

0– -1

0–1

1–5

5–10

10–50

50–100

>100

County boundaries of the United States, USGS 2000 National Atlas, 1:2,000,000-scale resolution, 2002, USGS;

Towns from USGS Geographic Names Information System, 1981. Coordinate System: NAD 1927. UTM Zone 12N.

Projection: Transverse Mercator. Datum: North American 1927. False Easting: 500,000.0000. False Northing: 0.0000. 

Central Meridian: -111.0000. Scale Factor: 0.9996. Latitude Of Origin: 0.0000. Units: Meter.

Figure 5. Map of water-level change for scenario 1 in the uppermost model layer from 2006 through 2105 near 

the Coconino Plateau Water Advisory Council scenario region and surrounding areas, Arizona. ADWR, Arizona 

Department of Water Resources.
Simulated Effects of Withdrawal Scenarios 23

Little

Colorado

Clear

Creek

Chevelon

Creek

Verde River

Creek

Creek

Beaver

River

Colorado

River

Creek Clear West

Creek

Burro

Creek

Trout

Oak

Creek

Havasu

Lake Mary

well field

Woody

Mountain

well field

Coconino

Plateau

basin

Little Colorado

River Plateau

basin

Verde Valley

Big Chino

sub-basin

Little

Chino

sub-basin

Fort Rock

sub-basin

Peach

Springs

sub-basin

sub-basin

Kaibab

Plateau

X

Black

Mesa

Mogollon Rim

Red Gap

Ranch

well field

Flagstaff

Local

well field

San Francisco

Mountain

Valle

Leupp

Parks Winona

Sedona

Tusayan

Cameron

Winslow

Red Lake

Williams

Tuba City

Flagstaff

Grand Canyon 

Village

Supai

Prescott

Munds

Park

Moenkopi

Blue Springs

Complex

113° 112° 111°

37°

36°

35°

Perennial streams from Arizona Department of Water Quality, 2015,

scale 1:100,000; Groundwater basin and sub-basin boundaries from

Arizona Department of Water Resources, 2008, scale 1:100,000

EXPLANATION

Town or landmark

Perennial streams

Simulated stream

Coconino County boundary

Groundwater basin and subbasin boundary

Model layer 1 active extent

Model layer 2 active extent

Model layer 3 active extent

5 10 20 30 40 MILES

0 20 40 60 80 10 KILOMETERS

0

Simulated difference in water levels in Scenario 2 relative to Scenario 1

Feet

<-100

-100 - -50

-50 - -10

-10 - -5

-5 - -1

-1 - 0

0 - 1

1 - 5

5 - 10

10 - 50

50 - 100

>100

County boundaries of the United States, USGS 2000 National Atlas, 1:2,000,000-scale resolution, 2002, USGS;

Towns from USGS Geographic Names Information System, 1981. Coordinate System: NAD 1927 UTM Zone 12N.

Projection: Transverse Mercator. Datum: North American 1927. False Easting: 500,000.0000. False Northing: 0.0000.

Central Meridian: -111.0000. Scale Factor: 0.9996. Latitude Of Origin: 0.0000. Units: Meter 

 

A

Figure 6. Map of the difference in water-level change in the uppermost model layer compared with scenario 1 from 

2006 to 2105 near the Coconino Plateau Water Advisory Council Scenario region and surrounding areas, Arizona for (A) 

Scenario 2 and (B) Scenario 3.
24 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

B

Little

Colorado

Clear

Creek

Chevelon

Creek

Verde River

Creek

Creek

Beaver

River

Colorado

River

Creek Clear West

Creek

Burro

Creek

Trout

Oak

Creek

Havasu

Coconino

Plateau

basin

Little Colorado

River Plateau

basin

Verde Valley

Big Chino

sub-basin

Little

Chino

sub-basin

Fort Rock

sub-basin

Peach

Springs

sub-basin

sub-basin

Kaibab

Plateau Black

Mesa

Mogollon Rim

Lake Mary

well field

Woody

Mountain

well field

X

Red Gap

Ranch

well field

Flagstaff

Local

well field San Francisco

Mountain

Valle

Leupp

Parks

Winona

Sedona

Tusayan

Cameron

Winslow

Red Lake

Williams

Tuba City

Flagstaff

Grand Canyon 

Village

Supai

Prescott

Munds

Park

Moenkopi

Blue Springs

Complex

113° 112° 111°

37°

36°

35°

Perennial streams from Arizona Department of Water Quality, 2015,

scale 1:100,000; Groundwater basin and sub-basin boundaries from

Arizona Department of Water Resources, 2008, scale 1:100,000

EXPLANATION

Town or landmark

Perennial streams

Simulated stream

Coconino County boundary

Groundwater basin and subbasin boundary

Model layer 1 active extent

Model layer 2 active extent

Model layer 3 active extent

5 10 20 30 40 MILES

0 20 40 60 80 10 KILOMETERS

0

Simulated difference in water levels in Scenario 3 relative to Scenario 1

Feet

<-100

-100 - -50

-50 - -10

-10 - -5

-5 - -1

-1 - 0

0 - 1

1 - 5

5 - 10

10 - 50

50 - 100

>100

County boundaries of the United States, USGS 2000 National Atlas, 1:2,000,000-scale resolution, 2002, USGS;

Towns from USGS Geographic Names Information System, 1981. Coordinate System: NAD 1927 UTM Zone 12N.

Projection: Transverse Mercator. Datum: North American 1927. False Easting: 500,000.0000. False Northing: 0.0000.

Central Meridian: -111.0000. Scale Factor: 0.9996. Latitude Of Origin: 0.0000. Units: Meter 

 

Figure 6.—Continued
Simulated Effects of Withdrawal Scenarios 25

vicinity of Williams and Flagstaff are 10 to 50 ft higher than 

simulated by scenario 1.

Simulated Changes in Groundwater Discharge

Simulated changes in groundwater discharge to streams 

and springs are discussed for each scenario. Groundwater 

discharge to streams, springs, and vegetation will decrease 

as a result of well withdrawals and increase with incidental 

recharge (Winter and others, 1998; fig. 7). Initial well withdrawals are derived from aquifer storage within the cone of 

depression around the well, which also creates local groundwater gradients that direct groundwater flow to the well 

(Barlow and Leake, 2012). The cone of depression is an area 

of decreased fluid pressure around the well, with the greatest 

decrease in fluid pressure at the well. As withdrawals from the 

well continue, the area of reduced fluid pressure expands and 

ultimately reaches any areas where groundwater discharges to 

surface features. Withdrawals later in time are derived from 

a combination of aquifer storage and decreased discharge to 

surface water features. The effect of incidental recharge is the 

opposite of well withdrawals, with water first going into storage and increasing discharge to surface features with time.

Simulated distributions of changes in groundwater 

discharge result from three factors including (1) the distance 

of each discharge feature to groundwater withdrawal wells or 

incidental recharge, (2) aquifer transmissivity, and (3) aquiferstorage properties. The rate of discharge change decreases 

with distance between the withdrawal or recharge and the 

discharge feature. The rate of discharge change increases with 

higher aquifer transmissivity and with lower aquifer-storage 

properties. Rates of discharge change will be greatest for a 

discharge feature that is hydraulically connected to a highly 

transmissive confined aquifer.

The NARGFM simulates groundwater discharge to 

streams, springs, and vegetation. This analysis focuses, however, on changes in discharge to streams and springs, which 

generally occur before changes in vegetation use. Eventually, 

given enough time with no further changes in well withdrawals and recharge rates, all of the well withdrawals will be 

derived from decreased groundwater discharge to surface 

features, no further change in aquifer storage will occur, and a 

new steady-state groundwater-flow system will be established. 

For this analysis, the effects of withdrawals for each scenario 

are analyzed for the period before 2105, which is long before a 

new steady-state flow system will be established. Any changes 

in storage that are simulated in 2105 will eventually, at some 

future time, result in an equivalent reduction in groundwater 

discharge to streams and springs. 

Simulated changes in groundwater discharge to streams 

and springs from 2006 to 2105 are discussed for major simulated perennial streams and springs that lie within and nearest to the CPWAC scenario region. These simulated features 

include the major perennial rivers—Colorado, Little Colorado, 

and Verde—and tributary streams including Havasu Creek, 

Clear Creek, Chevelon Creek, Silver Creek, Oak Creek, Sycamore Creek, Beaver Creek, and West Clear Creek. Simulated 

major springs in the CPWAC region include Havasu Spring, 

Blue Springs, and five of the major springs on the south rim 

of Grand Canyon—Royal Arch, Hermit, Monument, Indian 

Gardens, and Grapevine Springs. Groundwater discharge to all 

of these features can be captured by groundwater withdrawals 

or enhanced by artificial or incidental recharge. Groundwater 

discharge to other surface water features that are hydraulically connected to the Coconino and Redwall-Muav aquifers 

but not simulated may also change. These features that were 

not simulated, however, have less groundwater discharge than 

the simulated features. Simulation of changes in discharge to 

these features would require a more detailed groundwater flow 

model.

 Simulated changes in discharge occur at each of the 

major groundwater discharge features for all three scenarios, 

but most of the change before 2105 is very small (fig. 8). The 

greatest simulated changes in groundwater discharge occur 

with scenario 1. The most change is simulated for the Little 

Colorado River below Cameron (fig. 8D) and for Oak Creek 

above Page Springs (fig. 8G) where declines in discharge of 

about 1.3 and 1.1 cubic feet per second (ft3

/s) occur, respectively. Other simulated changes in discharge through 2105 are 

losses of less than 0.4 ft3/s at the Upper Verde River (fig. 8H), 

losses of less than 0.3 ft3/s at Havasu Creek (fig. 8A) and at 

Colorado River below Havasu Creek (fig. 8B), losses of less 

than 0.1 ft3/s at Clear Creek, and increases in flow at the south 

rim springs (fig. 8B) and Chevelon Creek (fig. 8F) of less than 

0.1 and 0.3 ft3/s, respectively. Simulated changes in discharge 

for scenarios 2 and 3 are less because of lower rates of groundwater withdrawal with respect to scenario 1.

Scenario 1

Reductions in groundwater discharge occur at most of the 

major perennial streams and springs near the CPWAC area for 

scenario 1. However, increases in discharge, both short-term 

and long-term, occur at some perennial features. The changes 

at each major discharge feature are discussed including explanations of the simulated change. 

The location of the greatest simulated losses in groundwater discharge along the Little Colorado River below 

Cameron result from several causes, including groundwater 

withdrawals from the Coconino aquifer in the Cameron and 

Moenkopi areas, relatively high transmissivity values in the 

region, and confined aquifer conditions east of Cameron 

including at a proposed well at Moenkopi. Losses in groundwater discharge to Oak Creek for scenario 1 are primarily 

the result of nearby large groundwater withdrawals at several wells including those at the Woody Mountain and Lake 

Mary well fields. The initial simulated increase in flow in 

Oak Creek, about 0.1 ft3/s before about 2010, is likely caused 

by the addition of incidental recharge at the nearby Kachina 

Village and Munds Park Wastewater Treatment facilities to 

the simulation. These incidental recharge features were not 
26 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

0.0

0.2

0.1

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Increasing time

Fraction of well pumping rate

Decrease in storage

Decrease in surface-water flow

plus decrease in evapotranspiration

Figure 7. Graph of 

sources of water, storage 

or surface-water flow and 

evapotranspiration, to a 

pumped well through time.

simulated in the original NARGFM and are a new source of 

simulated recharge beginning in 2006 for all three scenarios. 

The maximum decline in flow in Oak Creek of about 1.1 ft3/s 

by 2105 is less than 5 percent of the base flow of Oak Creek 

and well within the typical streamflow measurement error. 

Lesser rates of groundwater discharge decline are simulated at Havasu Creek (fig. 8A), the Colorado River below 

Havasu Creek (fig. 8B), and Upper Verde River (fig. 8H). 

Simulated declines in flow at Havasu Creek before 2040 are 

primarily caused by nearby supply wells for the Havasupai 

Tribe. The longer term decline in discharge of less than 

0.3 ft3/s in 2105, however, is likely caused by distant and 

regional groundwater withdrawals from the aquifer. The simulated rate of decline for Havasu Creek compared to the present 

day base flow of Havasu Creek (61 ft3/s) would be imperceptible. Simulated trends in declining groundwater discharge to 

the Colorado River below Havasu Creek are similar to those 

at Havasu Creek and have the same causes, but are slightly 

less in magnitude. Declines in groundwater discharge of less 

than 0.4 ft3/s to the upper Verde River above the streamflow 

gaging station near Clarkdale are likely a result of both the 

delayed effects of pre-2006 changes in nearby groundwater 

withdrawals, and post-2005 scenario 1 changes in distant 

groundwater withdrawals near Williams. The Redwall-Muav 

aquifer is simulated as highly transmissive in the region north 

of the Verde River; as a result distant well withdrawals may 

capture some groundwater discharge to the Verde River above 

the streamflow gaging station near Clarkdale. For comparison, 

the current base flow of the Verde River at Clarkdale is about 

69 ft3/s.

Long-term increases in simulated groundwater discharge 

(decades or longer duration), occurred for scenario 1 along 

several of the major perennial streams and springs, including springs at the south rim of Grand Canyon (fig. 8B), along 

Chevelon Creek (fig. 8F), and along Clear Creek (fig. 8E). The 

increased discharge at the south rim springs is likely caused by 

incidental recharge of treated effluent at the wastewater treatment plants at Grand Canyon and Tusayan, which are features 

that were included in all three scenarios, but were not included 

in the original NARGFM. The combined increase in flow of 

the south rim springs (Royal Arch, Hermit, Monument, Indian 

Gardens, and Grapevine) reaches a simulated maximum of 

about 0.1 ft3/s in about the year 2050. From this point on, the 

simulated change in flow for the combined south rim springs 

declines to about 0.05 ft3/s at year 2105.

Increased simulated discharge along Chevelon Creek 

through the simulated period results from pre-2006 changes in 

groundwater withdrawals and incidental recharge outside of 

the CPWAC area. These pre-2006 changes in stresses also are 

the cause of the simulated water-level recovery in the Chevelon Creek area and areas to the east (fig. 5). The simulated 

flow increase of about 0.3 ft3/s by about 2105 represents about 

an 11 percent increase in the current base flow of Chevelon 

Creek below the dam. Clear Creek (fig. 8E) displays a small 

increase in discharge before about 2030, which is caused by 

the same changes in pre-2006 stress that caused the greater 

and longer-term change in Chevelon Creek discharge. The 

increase in discharge at Clear Creek is reversed by the effects 

of nearby groundwater withdrawals after about 2030. This 

represents less than about 2 percent of the estimated summer 

base flow of Clear Creek (Leake and others, 2005). 

Scenarios 2 and 3

Simulated groundwater discharge for scenarios 2 and 3 

reflect the decrease in groundwater withdrawals resulting from 

importing surface water. Simulated discharge at major perennial streams and springs for scenarios 2 and 3 was greater than 

scenario 1 at many of the simulated groundwater discharge 

features (fig. 8). Scenarios 2 and 3 had no influence on simulated groundwater discharge at Clear and Chevelon Creeks 

from 2006 through 2105 (figs. 8E,F) because the reduced 

groundwater withdrawals are distant from those features and 

any effects may occur later. 

Scenario 2, reduced groundwater withdrawals in the 

Cameron area, produces results similar to scenario 1 for all 
Simulated Effects of Withdrawal Scenarios 27

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

Change in flow, in cubic feet per second 

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

Havasu Creek

Scenario 1

Scenario 2

Scenario 3

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

South Rim Springs

Clear Creek

Colorado River below Havasu Creek

-1.5

-1.0

-0.5

0.0

0.5

Little Colorado River below Cameron

A

C

E

D

B

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

H Upper Verde River

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

F Chevelon Creek

-1.5

-1.0

-0.5

0.0

0.5

Oak Creek above Page Springs

EXPLANATION

G

2000

2010

2020

2030

2040

2050

2060

2070

2080

2090

2100

2110

2000

2010

2020

2030

2040

2050

2060

2070

2080

2090

2100

2110

Figure 8. Simulated 

changes in groundwater 

discharge to major 

perennial surface 

water features from 

2006 through 2105 in 

and near the Coconino 

Plateau Water Advisory 

Council scenario region: 

(A) Havasu Creek, (B) 

Colorado River below 

Havasu Creek, (C) major 

springs at the south rim 

of Grand Canyon, (D) 

Little Colorado River 

below Cameron, (E) 

Clear Creek, (F) Chevelon 

Creek, (G) Oak Creek 

above Page Springs, 

and (H) upper part of the 

Verde River between 

the streamflow gaging 

stations near Paulden 

and near Clarkdale.

major groundwater discharge features except for the perennial reach of the Little Colorado River below Cameron, which 

is nearest to the reduced withdrawal area. Scenario 2 results 

in about 0.1 ft3

/s loss in simulated discharge through 2105 in 

comparison to discharge simulated in 2005, whereas scenario 

1 resulted in a loss in discharge of about 1.3 ft3/s .

Scenario 3 had a broader effect on groundwater discharge across the region because of a greater extent of reduced 

groundwater withdrawals. Scenario 3 resulted in greater 

groundwater discharge than scenarios 1 and 2 at all major 

groundwater discharge features from 2006 through 2105 

except for Clear and Chevelon Creeks. The effect on discharge 

to the Little Colorado River below Cameron was small with 

respect to scenario 2— about 0.05 ft3

/s more discharge was 

simulated in 2105—resulting in little change in discharge rate 

since 2006. Greater groundwater discharge was simulated 

by scenario 3 in comparison to scenarios 1 and 2 at Havasu 

Creek, Colorado River below Havasu Creek, Oak Creek 

above Page Springs, and upper Verde River. In 2105, scenario 

3 simulated discharge at Havasu Creek and the Colorado 

River below Havasu Creek was greater than that simulated 

by scenarios 1 and 2 by about 0.5 ft3

/s. Scenario 3 simulated 

groundwater discharge through 2105 at Oak Creek above Page 

Springs and the upper Verde River was greater than simulated 

by scenarios 1 and 2 by about 0.05 ft3

/s. Increases in discharge 

to Oak Creek and the upper Verde River are likely because of 

reduced simulated groundwater withdrawals near Flagstaff and 

Williams, respectively. Slightly greater groundwater discharge, 

about 0.02 ft3/s, was simulated by scenario 3 in comparison 

with scenario 1 and 2 at the south rim springs.

Model Limitations

The accuracy of hydrologic change that results from the 

simulation of the CPWAC withdrawal scenarios is dependent 

on the persistence of hydrologic assumptions that are inherent in the NARGFM. Major assumptions include, but are not 

limited to, the reasonably accurate simulation of (1) transmissivity distributions, (2) distributions of hydraulic properties 
28 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

that control interactions between vertically adjacent aquifers, 

(3) distributions of spatial, including vertical, withdrawal 

and incidental recharge rates, (4) aquifer extents, and (5) 

hydrologic barriers and conduits. In addition, no variations 

in recharge rates were simulated for the scenarios and no 

attempts were made to predict future recharge rates. Recharge 

rates were simulated as equivalent to average annual rates 

simulated for the original NARGFM. Future studies may 

result in an improved understanding of the groundwater-flow 

system that could substantially alter the conceptual hydrogeologic model in some areas. Commensurate modifications to 

the numerical model would be required, resulting in improved 

simulation of aquifer and stream-aquifer interactions and more 

reliable estimates of the effects of future groundwater use and 

management practices.

The accuracy of the simulated scenarios is limited to 

basin-scale applications and to regions of the model where 

geologic and hydrologic data are available, including records 

of steady-state water levels and base flow, and transient 

changes in water levels, base flow, and withdrawals. Basinscale applications refer to the simulation of overall water 

budgets and groundwater flow in a groundwater basin or 

large part of the basin. Few hydrologic records that document 

withdrawals and major changes in the hydrologic system are 

available across some regions of the groundwater flow system 

that are affected by the CPWAC withdrawal scenarios. The 

most prominent areas lacking hydrologic data include much 

of the Coconino Plateau basin, parts of the Little Colorado 

River Plateau basin, and the Verde Valley subbasin. Future 

data collection in these areas, especially the Coconino Plateau 

basin, may alter the current understanding and simulation of 

the groundwater flow system in those areas. Accordingly, the 

hydrologic system simulated by the NARGFM should not be 

considered a simulation of the true system, but a simulation of 

the system as currently understood and simplified for simulation by using a numerical model. However, the ultimate hydrologic effect of any groundwater withdrawal scenario is limited 

by the magnitude of the net withdrawals. 

Summary

The NARGFM was used to estimate the hydrologic 

changes—including changes in water levels and groundwater discharge to streams and springs—that may result from 

future groundwater withdrawals in and near the CPWAC 

study area in Coconino and Navajo Counties, Arizona. Three 

future withdrawal scenarios developed by the CPWAC for the 

2006 through 2050 period were tested. Simulated water levels 

resulting from each scenario in 2105 were compared, as were 

simulated changes in groundwater discharge to major perennial streams and springs. 

The NARGFM uses the USGS developed finite-difference code MODFLOW-2005 to simulate groundwater flow 

within the major aquifers of northern Arizona and parts of 

adjacent states. The model includes the region of the Colorado 

Plateau and adjacent areas to the south that include alluvial 

basins. Three model layers are used to simulate the primary 

hydrogeologic units across the model domain. Within and 

surrounding the area of the CPWAC withdrawal scenarios, the 

major simulated aquifers are the Coconino and Redwall-Muav 

aquifers. The upper part of the Coconino aquifer, included 

within model layer 1, is primarily in the region north and east 

of the Little Colorado River. The lower part of the Coconino 

aquifer, included within model layer 2, is simulated where the 

upper and middle Supai Formations are regionally saturated in 

the region east of a line from Cameron to Williams. Alluvial 

aquifers are simulated in the adjacent Verde Valley and include 

the fluvio-lacustrine facies of the Verde Formation, which are 

simulated within model layer 1, and the sand and gravel facies 

of the Verde Formation, which are simulated as model layer 

2. The Redwall-Muav aquifer is simulated as model layer 

3 throughout most of the region of the CPWAC withdrawal 

scenarios.

The NARGFM simulates aquifer recharge and discharge 

to streams and springs, and evapotranspiration by phreatophytes. Recharge rates and distributions are derived from a 

basin characterization model that estimates recharge as direct 

infiltration. The recharge estimates are modified in alluvial 

basins to include infiltration along ephemeral stream channels. Discharge to streams and springs are simulated using the 

MODFLOW stream package for perennial streams within the 

Verde and Little Colorado River drainage systems, and the 

MODFLOW drain package for other perennial streams and 

major springs including the Colorado and Salt Rivers.

Three future groundwater withdrawal scenarios, developed by the CPWAC for tribal and nontribal uses, were simulated for the period 2006–2105. Most of the withdrawal wells 

for each scenario are within the Coconino Plateau basin and 

the Little Colorado River Plateau basin. Scenario 1 assumes 

no major changes in groundwater use except for increased 

demand based on population projections. Total groundwater 

withdrawals within the CPWAC region for scenario 1 increase 

from about 10,800 ac-ft/yr during 2006 through 2009 to about 

25,300 ac-ft/yr after 2049 (fig. 3A, appendix 1). Scenario 2 

assumes that a pipeline will provide a source of surface water 

from Lake Powell to the communities along the west edge of 

the Navajo Reservation including Cameron and Moenkopi, 

and all nontribal water demands will continue to be met by 

groundwater development. Total groundwater withdrawals 

within the CPWAC region for scenario 2 increase from about 

10,800 ac-ft/yr during 2006 through 2009 to about 

23,000 ac-ft/yr after 2049. Most of increases in groundwater 

withdrawals for scenarios 1 and 2 result from increases for 

the City of Flagstaff at the Inner City well field and at nearby 

communities. Scenario 3 assumes that a pipeline extends onto 

the Coconino Plateau to supply projected unmet demands for 

water in this area by 2050. Total groundwater withdrawals for 

scenario 3 are the least of the three scenarios, and increase 

from about 10,800 ac-ft/yr during 2006 through 2009 to about 

23,400 ac-ft/yr after 2049. Similar to scenarios 1 and 2, most 
Summary 29

of increases in groundwater withdrawals for scenario 3 result 

from increases near Flagstaff. Overall groundwater withdrawals for scenario 3 after 2049 are about 4,300 ac-ft/yr less than 

those in scenario 1. 

A few additional assumptions were applied to the withdrawal scenarios regarding rates of natural and incidental 

recharge, rates of projected withdrawals outside of the area 

of the scenarios, withdrawal rates for exempt wells, and how 

to handle loss of withdrawals that occur as a result of model 

cells that dry during the simulations. Natural recharge rates 

for the three simulated groundwater withdrawal scenarios are 

assumed to be equivalent to average-annual rates of natural 

recharge that applied to the NARGFM for the simulation 

of pre-2006 conditions. This eliminates the effects of natural recharge from the simulated changes and simplifies the 

analysis. Projected rates of incidental recharge for waste water 

treatment facilities at 12 communities within the CPAC scenario region were assumed to remain at a constant percentage 

of water demand from 2000 through 2005. Projected rates of 

incidental recharge at eight golf courses was constant throughout the simulations. Well withdrawals outside of the CPWAC 

scenario area were maintained at rates that were simulated in 

the NARGFM during 2000 through 2005. Drying of model 

cells that include well withdrawals outside of the scenario area 

was allowed to occur. Dry models cells and loss of simulated 

withdrawals at those cells were nearly identical for each 

scenario and did not greatly affect results. Withdrawals from 

exempt wells and a few other wells were assumed to vary in 

the future based on variations in the “other” withdrawal category provided by each scenario. Distributions of withdrawals 

for some wells within the scenario area, mainly near the City 

of Flagstaff wells fields and near Holbrook, were modified 

from the pre-2006 simulation for the purpose of preventing 

drying of the pumped model cell and retention of the projected 

withdrawals throughout the period of the simulation. Modifications included redistribution of the withdrawals to include 

deeper layers and lateral translation of wells to spread the collective cone of depression resulting from a concentrated area 

of well withdrawals.

The CPWAC withdrawal scenarios primarily influence 

water levels and groundwater discharge in the Coconino 

Plateau basin, near the western margin of the Little Colorado 

River Plateau basin, and the Verde Valley subbasin. Simulated effects of the withdrawal scenarios are superimposed on 

effects of previous variations in groundwater withdrawals and 

artificial and incidental recharge. Effects of these pre-scenario 

variations include changes in water-levels in wells, groundwater storage, discharge to streams and springs, and evapotranspiration by plants that use groundwater. Future variations in 

groundwater discharge will continue to occur as a result of the 

past changes. 

Water-level variations resulting from post-2005 groundwater withdrawals and incidental and artificial recharge in the 

area of the withdrawal scenarios are primarily localized and 

superimposed on the regional changes caused by pre-2006 

variations. Withdrawal scenario 1 produced a broad region on 

the Coconino Plateau where water-levels declined by 1–5 ft 

by 2105 and local areas with water-level declines of 100 ft or 

more where groundwater withdrawals are concentrated near 

the City of Flagstaff Woody Mountain and Lake Mary well 

fields, and the towns of Tusayan and Parks. Water-level rises 

of more than 100 ft are simulated near the City of Flagstaff 

waste-water treatment plants at Wildcat Hill, Rio De Flag, and 

Grand Canyon Village.

Simulated water-level change from 2006 through 2105 

for scenarios 2 and 3, which bring imported surface water to 

the area and remove some groundwater withdrawals, is mostly 

different from water-level change at the local level simulated 

for scenario 1, which includes no imported water to relieve 

groundwater withdrawals. Scenarios 2 and 3 both eliminate 

groundwater withdrawals in the reservation areas extending 

from Lake Powell to, and including, Cameron, where water 

levels in 2105 were 1 to 5 ft higher than simulated for scenario 

1. Water levels at Moenkopi are more than 10 ft higher due to 

the elimination of a proposed withdrawal well that was simulated in scenario 1. Scenario 3 eliminates more groundwater 

withdrawals in the Flagstaff and Williams areas; it also simulates 1 to 5 ft less water-level decline than scenario 1 across 

much of the Coconino Plateau, and 10 to 50 ft higher water 

levels than simulated by scenario 1 near withdrawal wells in 

the Williams and Flagstaff areas.

Simulated changes in discharge occur at each of the 

major groundwater discharge features for all three scenarios, 

but most of the change before 2105 is very small. Scenario 1, 

which includes no imported surface water to replace groundwater withdrawals, simulated the most change in groundwater 

discharge for the Little Colorado River below Cameron and 

for Oak Creek above Page Springs, where discharge declines 

about 1.3 and 1.1 ft3

/s , respectively. Other simulated changes 

in discharge through 2105 in scenario 1 are losses of less than 

0.4 ft3/s at the upper Verde River, losses of less than 0.3 ft3/s 

at Havasu Creek and at the Colorado River below Havasu 

Creek, minimal change at Clear Creek, and increases in flow 

at the south rim springs and Chevelon Creek of less than 0.1 

and 0.3 ft3/s , respectively. Simulated changes in discharge for 

scenarios 2 and 3 are less because of lower rates of groundwater withdrawal with respect to scenario 1.

Scenario 3 maintained the greatest simulated rates of 

groundwater discharge to major streams and springs. The 

scenario includes the importation of surface water for both 

tribal and nontribal demand in the CPWAC study area and 

reduced groundwater withdrawals. Scenario 3 resulted in 

greater groundwater discharge than scenarios 1 and 2 at all 

major groundwater discharge features from 2006 through 

2105 except for Clear and Chevelon Creeks, where the same 

groundwater discharge was simulated by each of the three 

scenarios. Groundwater discharge to the Little Colorado River 

below Cameron was greatest for scenarios 2 and 3. Scenario 3 

resulted in almost no change in discharge after 2005. Scenario 

2 resulted in about 0.1 ft3

/s loss in discharge by 2105. Greater 

flows were simulated by scenario 3 in comparison to scenarios 

1 and 2 at Havasu Creek, Colorado River below Havasu 
30 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona

Creek, south rim springs, Oak Creek above Page Springs, and 

the upper Verde River. However, the increased flows in 2105 

in scenario 3 flows over scenario 2 were very small at all of 

these features, less than about 0.1 ft3/s. Changes in groundwater discharge will occur after 2105 to all major surface features 

that discharge from the Redwall-Muav and Coconino aquifers 

because change in aquifer storage was occurring at the end of 

the simulation in 2105.

 The accuracy of simulated changes resulting from the 

CPWAC groundwater withdrawal scenarios is dependent on 

the persistence of several hydrologic assumptions that are 

inherent in the NARGFM including, but not limited to, the 

reasonably accurate simulation of (1) transmissivity distributions, (2) distributions of vertical hydraulic properties, (3) 

distributions of spatial rates of withdrawal and incidental 

recharge, (4) aquifer extents, and (5) hydrologic barriers and 

conduits. The model can be improved with knowledge gained 

from future investigations. Much of the hydrogeology in the 

simulated area is poorly understood because of limited subsurface investigations and few long-term records of hydrologic 

change. The most prominent areas lacking hydrologic data 

include much of the Coconino Plateau basin, parts of the Little 

Colorado River Plateau basin, and the Verde Valley subbasin. 

Future data collection in these areas, especially the Coconino 

Plateau basin, may alter the current understanding and simulation of the groundwater flow system in those areas. Accordingly, the hydrologic system simulated by the NARGFM 

should not be considered a simulation of the true system, but 

a simulation of the system as it is currently understood and 

simplified for simulation by using a numerical model. 

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Winter, T.C., Harvey, J.W., Franke, O.L., and Alley, W.M., 

1998, Ground water and surface water—a single resource: 

U.S. Geological Survey Circular 1139, 79 p., accessed July 

14, 2010, at http://pubs.usgs.gov/circ/circ1139/.

Wirt, Laurie, DeWitt, Ed, and Langenheim, V.E., 2005, Geologic framework of aquifer units and groundwater flowpaths, Verde River headwaters, north-central Arizona: U.S. 

Geological Survey Open-File Report 2004–1411, variously 

paged.

Wolfe, E.W., Newhall, C.G., and Ulrich, G.E., 1987b, Geologic map of the northwest part of the San Francisco Volcanic Field, north-central Arizona: U.S. Geological Survey 

Miscellaneous Field Studies Map MF–1957, 2 sheets, scale, 

1:50,000.

Wolfe, E.W., Ulrich, G.E., Holm, R.F., Moore, R.B., and 

Newhall, C.G., 1987a, Geologic map of the central part of 

the San Francisco Volcanic Field, north-central Arizona: 

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MF–1959, 2 sheets, scale, 1:50,000.
Appendixes
Appendix 1 33

Appendix 1. Groundwater demand scenario 1 developed by the Coconino Plateau Water Advisory Council for the period 2006–2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM. [Values in acre-feet per year]

Category Area Water user Aquifer

Scenario 1 water use

by simulated decade

2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105

Municipal, 

Tribal, and 

Industrial 

groundwater 

withdrawals

Moenkopi/Lower Moenkopi Hopi Tribe Coconino 26 34 70 94 127 170

Havasupai Havasupai Tribe Redwall-Muav 170 175 175 200 200 200

Hualapai Hualapai Tribe Other1 0 0 1 5 10 10

Bodaway/Gap Navajo Tribe Other1/Coconino 169 196 301 445 629 750

Cameron Navajo Tribe Coconino 196 230 371 485 632 819

Leupp Navajo Tribe Coconino 200 230 302 374 446 518

Leupp wells (Seba Delka, 

Dilkon, Red Lake, etc.)

Navajo Tribe Coconino 0 0 50 250 500 500

Twin Arrows Casino Navajo Tribe Coconino 0 9 500 500 500 500

Inner Basin wells and 

springs

City of Flagstaff Coconino 274 700 700 700 700 700

Lake Mary well field City of Flagstaff Coconino 2,576 1,650 1,650 1,650 1,650 1,650

Woody Mountain well field City of Flagstaff Coconino 2,701 2,700 2,954 3,231 3,585 3,968

Local well field City of Flagstaff Coconino 1,475 2,042 2,607 3,176 3,743 4,310

Red Gap Ranch City of Flagstaff Coconino 0 0 500 1,500 3,000 4,348

Bellmont 

(Flagstaff Meadows)

Bellmont (Flagstaff 

Meadows)

Coconino 25 50 75 100 125 150

Doney Park Doney Park Coconino 781 974 1,168 1,362 1,556 1,755

Flagstaff Ranch Flagstaff Ranch Coconino 100 125 125 112 100 100Forest Highlands Forest Highlands Coconino 570 600 600 600 600 600

Fox Ranch Fox Ranch Coconino 0 10 10 20 20 40

Fort Valley Fort Valley Coconino 0 20 40 60 80 95

Kachina Kachina Coconino 342 354 366 378 390 400

Mountainare Mountainare Coconino 90 99 108 117 125 135Mountain Dell Water 

Company

Mountain Dell 

Water Company

Coconino 20 23 25 25 30 30

Parks Parks Other1/Coconino 200 200 275 350 425 490

Tusayan Tusayan Redwall-Muav 75 225 275 325 375 425

Valle Valle Redwall-Muav 50 117 134 151 168 185

Williams City of Williams Redwall-Muav 280 360 440 520 600 675

Canyon Mine Canyon Mine Redwall 0 4 40 4 0 0

Williams Bearazona Wildlife Park Redwall 0 60 120 120 120 120
34 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona Appendix 1. Groundwater demand scenario 1 developed by the Coconino Plateau Water Advisory Council for the period 2006–2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM.—Continued. Category Area Water user Aquifer Scenario 1 water use by simulated decade 2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105 Other domes- tic, stock and small industrial groundwater withdrawals Williams to Grand Canyon area Stock and domestic Other1/Redwall- Muav 125 130 200 270 340 410 Flagstaff to Williams area Stock and domestic Coconino/Red- wall-Muav 250 255 395 535 675 815 Remaining area Stock and domestic Coconino/Red- wall-Muav 125 130 200 270 340 410 Non-NARGFM groundwater withdrawals Hopi Hopi Tribe Navajo 64 98 198 265 362 497 Coppermine Navajo Tribe Navajo 62 70 110 163 230 275 LeChee Navajo Tribe Navajo 175 203 310 457 946 946 Tuba City Navajo Tribe Navajo 1,393 1,623 2,603 2,285 4,379 5,648 Total annual groundwater withdrawal 12,514 13,696 17,998 21,099 27,708 32,644 Total annual NARGFM simulated groundwater withdrawal 10,820 11,702 14,777 17,929 21,791 25,278 Annual withdrawals from aquifers not simulated using NARGFM 1,694 1,994 3,221 3,170 5,917 7,366

1Aquifers in younger rocks including those of local extent in alluvial and volcanic rocks that may be perched or hydraulically disconnected from the underlying simulated aquifers, but may discharge 

groundwater to the simulated aquifers. 
Appendix 2 35

Appendix 2. Groundwater demand scenario 2 developed by the Coconino Plateau Water Advisory Council for the period 2006–2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM.[Values in acre-feet per year]

Category Area Water user Aquifer

Scenario 2 water use

by simulated decade

2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105

Municipal, 

Tribal, and 

Industrial 

groundwater 

withdrawals

Moenkopi/Lower Moenkopi Hopi Tribe Coconino 26 0 0 0 0 0

Havasupai Havasupai Tribe Redwall-Muav 170 175 175 200 200 200

Hualapai Hualapai Tribe Other1 0 0 1 5 10 10

Bodaway/Gap Navajo Tribe Other1/Coconino 169 0 0 0 0 0

Cameron Navajo Tribe Coconino 196 0 0 0 0 0

Leupp Navajo Tribe Coconino 200 230 302 374 446 518Leupp wells (Seba Delka, 

Dilkon, Red Lake, etc.)

Navajo Tribe Coconino 0 0 50 250 500 500

Twin Arrows Casino Navajo Tribe Coconino 0 9 500 500 500 500Inner Basin wells and 

springs

City of Flagstaff Coconino 274 700 700 700 700 700

Lake Mary well field City of Flagstaff Coconino 2,576 1,650 1,650 1,650 1,650 1,650Woody Mountain well field City of Flagstaff Coconino 2,701 2,700 2,954 3,231 3,585 3,968Local well field City of Flagstaff Coconino 1,475 2,042 2,607 3,176 3,743 4,310Red Gap Ranch City of Flagstaff Coconino 0 0 500 1,500 3,000 4,348

Bellmont 

(Flagstaff Meadows)

Bellmont (Flagstaff 

Meadows)

Coconino 25 50 75 100 125 150

Doney Park Doney Park Coconino 781 974 1,168 1,362 1,556 1,755Flagstaff Ranch Flagstaff Ranch Coconino 100 125 125 112 100 100Forest Highlands Forest Highlands Coconino 570 600 600 600 600 600Fox Ranch Fox Ranch Coconino 0 10 10 20 20 40Fort Valley Fort Valley Coconino 0 20 40 60 80 95Kachina Kachina Coconino 342 354 366 378 390 400Mountainare Mountainare Coconino 90 99 108 117 125 135Mountain Dell Water 

Company

Mountain Dell 

Water Company

Coconino 20 23 25 25 30 30

Parks Parks Other1/Coconino 200 200 275 350 425 490

Tusayan Tusayan Redwall-Muav 75 225 275 325 375 425Valle Valle Redwall-Muav 50 117 134 151 168 185

Williams City of Williams Redwall-Muav 280 360 440 520 600 675Canyon Mine Canyon Mine Redwall 0 4 40 4 0 0

Williams Bearazona Wildlife Park Redwall 0 60 120 120 120 120
36 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona Appendix 2. Groundwater demand scenario 2 developed by the Coconino Plateau Water Advisory Council for the period 2006–2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM.—Continued. Category Area Water user Aquifer Scenario 2 water use by simulated decade 2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105 Other domes- tic, stock and small industrial groundwater withdrawals Williams to Grand Canyon area Stock and domestic Other1/Redwall- Muav 125 130 200 270 340 410 Flagstaff to Williams area Stock and domestic Coconino/Red- wall-Muav 250 255 395 535 675 815 Remaining area Stock and domestic Coconino/Red- wall-Muav 125 130 200 270 340 410 Non-NARGFM groundwater withdrawals Hopi Hopi Tribe Navajo 64 0 0 0 0 0 Coppermine Navajo Tribe Navajo 62 0 0 0 0 0 LeChee Navajo Tribe Navajo 175 0 0 0 0 0 Tuba City Navajo Tribe Navajo 1,393 0 0 0 0 0 Total annual groundwater withdrawal 12,514 11,178 13,875 16,781 20,283 23,419 Total annual NARGFM simulated groundwater withdrawal 10,820 11,178 13,875 16,781 20,283 23,419 Annual withdrawals from aquifers not simulated using NARGFM 1,694 0 0 0 0 0

1Aquifers in younger rocks including those of local extent in alluvial and volcanic rocks that may be perched or hydraulically disconnected from the underlying simulated aquifers, but may discharge 

groundwater to the simulated aquifers. 
Appendix 3 37

Appendix 3. Groundwater demand scenario 3 developed by the Coconino Plateau Water Advisory Council for the period 2006– 2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM. [Values in acre-feet per year]

Category Area Water user Aquifer

Scenario 3 water use

by simulated decade

2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105

Municipal, 

Tribal, and 

Industrial 

groundwater 

withdrawals

Moenkopi/Lower Moenkopi Hopi Tribe Coconino 26 0 0 0 0 0

Havasupai Havasupai Tribe Redwall-Muav 170 175 175 200 200 200

Hualapai Hualapai Tribe Other1 0 0 1 5 10 10

Bodaway/Gap Navajo Tribe Other1/Coconino 169 0 0 0 0 0

Cameron Navajo Tribe Coconino 196 0 0 0 0 0

Leupp Navajo Tribe Coconino 200 230 302 374 446 518Leupp wells (Seba Delka, 

Dilkon, Red Lake, etc.)

Navajo Tribe Coconino 0 0 50 250 500 500

Twin Arrows Casino Navajo Tribe Coconino 0 9 500 500 500 500Inner Basin wells and 

springs

City of Flagstaff Coconino 274 700 700 700 700 700

Lake Mary well field City of Flagstaff Coconino 2,576 1,650 1,650 1,650 1,650 1,650

Woody Mountain well field City of Flagstaff Coconino 2,701 2,700 2,954 3,231 3,585 3,968

Local well field City of Flagstaff Coconino 1,475 2,042 2,500 2,500 2,500 2,500

Red Gap Ranch City of Flagstaff Coconino 0 0 500 1,500 3,000 4,348

Bellmont 

(Flagstaff Meadows)

Bellmont (Flagstaff 

Meadows)

Coconino 25 50 75 100 125 150

Doney Park Doney Park Coconino 781 974 1,168 1,362 1,556 1,755Flagstaff Ranch Flagstaff Ranch Coconino 100 125 125 112 100 100Forest Highlands Forest Highlands Coconino 570 600 600 600 600 600Fox Ranch Fox Ranch Coconino 0 10 10 20 20 40Fort Valley Fort Valley Coconino 0 20 40 60 80 95Kachina Kachina Coconino 342 354 366 378 390 400Mountainare Mountainare Coconino 90 99 108 117 125 135Mountain Dell Water 

Company

Mountain Dell 

Water Company

Coconino 20 23 25 25 30 30

Parks Parks Other1/Coconino 200 200 275 350 425 490

Tusayan Tusayan Redwall-Muav 75 225 275 325 375 425Valle Valle Redwall-Muav 50 117 134 151 168 185

Williams City of Williams Redwall-Muav 280 360 0 0 0 0

Canyon Mine Canyon Mine Redwall 0 4 40 4 0 0

Williams Bearazona Wildlife Park Redwall 0 60 120 120 120 120
38 Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona Appendix 3. Groundwater demand scenario 3 developed by the Coconino Plateau Water Advisory Council for the period 2006– 2105 including groundwater demand simulated for the Coconino and Redwall-Muav Aquifers using the Northern Arizona Groundwater Flow Model (NARGFM) and groundwater demand for overlying and disconnected aquifers that are not simulated using NARGFM. Category Area Water user Aquifer Scenario 3 water use by simulated decade 2006-2009 2010-2019 2020-2029 2030-2039 2040-2049 2050-2105 Other domes- tic, stock and small industrial groundwater withdrawals Williams to Grand Canyon area Stock and domestic Other1/Redwall- Muav 125 130 200 270 340 410 Flagstaff to Williams area Stock and domestic Coconino/Red- wall-Muav 250 255 395 535 675 815 Remaining area Stock and domestic Coconino/Red- wall-Muav 125 130 200 270 340 410 Non-NARGFM groundwater withdrawals Hopi Hopi Tribe Navajo 64 0 0 0 0 0 Coppermine Navajo Tribe Navajo 62 0 0 0 0 0 LeChee Navajo Tribe Navajo 175 0 0 0 0 0 Tuba City Navajo Tribe Navajo 1,393 0 0 0 0 0 Total annual groundwater withdrawal 12,514 11,178 13,328 15,585 18,440 20,934 Total annual NARGFM simulated groundwater withdrawal 10,820 11,178 13,328 15,585 18,440 20,934 Annual withdrawals from aquifers not simulated using NARGFM 1,694 0 0 0 0 0

1Aquifers in younger rocks including those of local extent in alluvial and volcanic rocks that may be perched or hydraulically disconnected from the underlying simulated aquifers, but may discharge 

groundwater to the simulated aquifers. 
Menlo Park Publishing Service Center, California

Manuscript approval date August 3, 2016

Edited by Katherine Jacques

Design and layout by Vivian Nguyen
Pool—Simulation of Groundwater Withdrawal Scenarios for the Redwall-Muav and Coconino Aquifer Systems of Arizona—Scientific Investigations Report 2016–5115

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20165115