Prepared in cooperation with the

ARIZONA DEPARTMENT OF WATER RESOURCES

USGS Fact Sheet 159-00

December 2000

Investigation of the Geology and Hydrology of the Mogollon

Highlands of Central Arizona: A Project of the Arizona Rural

Watershed Initiative

The Mogollon Highlands of east

central Arizona is a region of forested

plateau and mountains, deep, sheerwalled canyons, and desert valleys.

Known for its scenic beauty and

characterized by a generally mild climate,

the area, though still sparsely populated,

attracts an increasing number of tourists

and summer residents. Furthermore, the

permanent population is expected to

nearly double over the next 50 years.

Consequently, there is increased pressure

on the water resources of this area for

several sometimes conflicting uses.

Rational management of water resources

is necessary to meet increased domestic

requirements while ensuring an adequate

supply of water for commercial and

agricultural use, for Indian lands, and for

preservation of valued environmental

elements, including surface waters,

riparian woodlands, forest and grassland

areas, and wildlife and aquatic habitat.

Such management requires an understanding of the relations among different

components of the hydrologic

system—recharge areas, surface flows,

shallow aquifers, deep aquifers, discharge

areas, and the regional ground-water flow

system—and how each is affected by

geology, climate, topography, and human

use.

The U.S. Geological Survey (USGS)

is conducting an assessment of the

hydrogeology of the Mogollon Highlands

in cooperation with the Arizona

Department of Water Resources. The

study, funded through the State’s Rural

Watershed Initiative program, is one of

three assessments being conducted by the

USGS. Assessments also are underway

in the Upper-Middle Verde River

watershed and on the Coconino Plateau.

Each study has as its objectives: (1) the

collection, compilation, and evaluation of

all existing geologic, hydrologic, and

related data pertaining to the study area

and the creation of a data base that is

readily accessible to the public and (2)

U.S. Department of the Interior

U.S. Geological Survey

0

0

10 MILES

10 KILOMETERS

COLORADO

PLATEAU

Fossil Creek

East Verde River

SIERRA ANCHA

Overgaard

Payson

Rye

Theodore

Roosevelt

Lake

Kohls Ranch

Tonto

Village

Pine

Tonto Creek

Cherry Creek

Canyon Cr e ek

Salt

River

M

AZATZAL MOUNTAINS

Strawberry

Verde River

110 ̊30'

34 ̊30'

34 ̊00'

MOGOLLON

RIM

111 ̊30'

Mogollon

Highlands

study

area

111 ̊00'

Figure 1. Location of Mogollon Highlands study area. The dark brown line delineates

the primary study area;the more extensive area of light-brown tones delineates the proposed

boundaries for regional ground-water flow modeling.

developing an understanding of the

hydrogeologic framework, which is the

relation between geologic and hydrologic

properties, that can be used for water--

resources management purposes and that

will support the development of an

interpretive and predictive model to

estimate the effects of climate and water

use on the sustainability of regional water

resources.

Although the three continguous areas

in north-central Arizona are being studied

separately, a single data base is being

constructed from which

data on each area can

be extracted separately.

ARIZONA
Physical Setting

The extended study area encompasses

about 4,855 mi2 (fig. 1), and the main

area of focus includes the Fossil Creek,

East Verde River, and Tonto Creek

Basins below the Mogollon Rim. The

Mogollon Rim is the eroded and

dissected southwestern edge of the

Colorado Plateau and is one of the most

striking physical features in the study

area; it trends mainly east-west for about

80 miles, forming a steep escarpment

about 2,000 ft above a lower, stepped

plateau. South of the Mogollon Rim, the

Transition Zone, an area of mountain

ranges and valleys, separates the

Colorado Plateau from the Basin and

Range province. Altitudes within the

study area range from more than 7,500 ft

at the top of the Mogollon Rim to about

1,500 ft at the mouth of the Verde

River.a Precipitation ranges from more

than 30 in. at the higher elevations to

about 15 in. annually at the lowest desert

locations. Above about 5,000 ft,a

vegetation is primarily Ponderosa pine

forest with piñon pine and juniper

woodland, oak woodland, and Sonoran

desert vegetation at successively lower

altitudes. Population of the study area is

approximately 21,000, about two thirds

of which live in the town of Payson.

According to the Arizona State Land

Department, about 80 percent of the land

is owned by the Federal government,

primarily within the Tonto National

Forest, and about 15 percent of the land

is included within five Indian

reservations. Only 2.4 percent of the land

within the study area is privately owned.

Geology

The edge of the Mogollon Rim

exposes a sequence, nearly 3,000 ft

thick,aof Paleozoic sedimentary rocks

that are capped by Tertiary volcanic

rocks in the western part of the study area

(fig. 2). The Paleozoic section is

underlain by Precambrian rocks including

the Mazatzal Quartzite and the Payson

granite. The Payson granite forms a

topographic bench along the base of the

rim that extends for about 10 miles west

to east. The town of Payson sits upon this

exposure of granite. South of Payson, the

Mazatzal Mountains and Sierra Ancha

consist largely of Precambrian sedimentary, volcanic, and metamorphic

rocks. The two mountain ranges flank the

valley of Tonto Creek, which is filled

with alluvium of Quaternary and Tertiary

age to a depth of about 5,000 ft

(Wilson and others, 1959; Feth and Hem,

1963; Mayer, 1978; Richards, 1987;

Weisman and Weir, 1990; Weir and

Beard, 1997).

The most significant structural

characteristics include the shallow

northeastward dip of the Paleozoic

rocks;a the extensive fracturing of

sedimentary and granitic rocks; solution

features, such as caverns, in carbonate

rocks; and northwest-southeast trending

extensional faults associated with Basin

and Range deformation. The Diamond Rim

Fault, which forms a secondary escarpment

generally less than 1,000 ft high below the

main escarpment of the Mogollon Rim east

of Payson, is the largest and most

continuous of the northwest-southeast

trending extensional faults.

Hydrology

Perennial surface-water flows are the

result of ground-water discharge and are

restricted mainly to the major streams of

Fossil Creek, the East Verde River, and

Tonto Creek plus a few of their larger

tributaries. Other streams are intermittent

or ephemeral.

The ground-water system consists of

several components including multiple

aquifers within the sedimentary rocks of

the Mogollon Rim, water-bearing zones

PERMIAN

VOLCANIC ROCKS

KAIBAB FORMATION

COCONINO SANDSTONE

UPPER SUPAI FORMATION

LOWER SUPAI FORMATION

NACO FORMATION

REDWALL LIMESTONE

MARTIN FORMATION

TAPEATS SANDSTONE

MAZATZAL QUARTZITE

PAYSON GRANITE

DIRECTION OF WATER MOVEMENT

FAULT

AREA OF FRACTURES

SIGNIFICANT DISCONFORMITY

TERTIARY

NORTH EXPLANATION

SOUTH

PENNSYLVANIAN

MISSISSIPPIAN

DEVONIAN

CAMBRIAN

PRECAMBRIAN

Figure 2. Schematic diagram of geology of the study area showing a generalized north

to south cross section from the crest of the Mogollon Rim to the granitic terrain around

the town of Payson. Springs may be fed directly from recharge areas on top of the Mogollon

Rim or may be fed from deeper ground-water systems.

? ? ? ?

within fractured parts of the Payson

granite, and alluvial aquifers in the basin

fill of the Tonto Creek Basin and along

some streams. Some springs discharge

from the Precambrian rocks of the Sierra

Ancha and Mazatzal Mountains, but the

hydrologic characteristics of those rocks

are not well known. The aquifers within

the sedimentary rocks are recharged from

precipitation falling on the southern edge

of the Colorado Plateau. Permeability

within the sedimentary rocks generally is

the result of fracturing, jointing, and

faulting of rocks of otherwise low

permeability. Within carbonate rocks,

permeability can be increased by the

formation of solution features, such as

conduits and caverns, by widening of

joints and fractures, and by dissolution of

beds. The cap rocks of the Mogollon Rim,

which can be Tertiary basalt, and

limestone or sandstone of the Kaibab

Formation and Coconino Sandstone,

generally are highly fractured and permit

rapid infiltration of surface waters to lower

layers. Waters infiltrating the sedimentary

rocks frequently discharge at springs on

the face of the Mogollon Rim and along

canyon walls and stream channels

particularly where permeable rocks overlie

less permeable rocks or where fractures or

faults force ground-water flow to the

surface (Feth and Hem, 1963).
Figure 4. A spring discharging into Fossil Creek.

0

0

10 MILES

10 KILOMETERS

Pine

Salt

River

Strawberry

River

Verde

110 ̊30'

34 ̊30'

34 ̊00'

111 ̊30' 111 ̊00'

Figure 3. Locations of wells and springs in the study area.

WELL

SPRING

EXPLANATION

Payson

Although the Coconino Sandstone is

an important aquifer elsewhere on the

Colorado Plateau, most communities

within the study area obtain water for

domestic use from lower-lying formations,

particularly the Supai and Naco

Formations. The lower Paleozoic

formations, including the Redwall

Limestone and Martin Formation, are

productive aquifers elsewhere as

indicated by spring discharge in several

streams, but they have not been developed

significantly in the study area. The town

of Payson obtains its water from wells in

the Payson granite. The location of water

within granitic rocks of the study area is

dependent on the degree of weathering,

fracturing, jointing, and faulting in the

rocks because unweathered, unfractured

granitic rocks have extremely low

primary porosity (Southwest Groundwater Consultants, Inc., 1998). A survey

of the USGS National Water Information

System (NWIS) ground-water data base

shows approximately 1,200 wells in the

study area (fig. 3). Most wells in the

northern half of the study area are in

bedrock aquifers; in the southern part of

the Tonto Creek Basin, most wells are in

valley fill alluvium. Average depth to

from an average of 900 gal/min in the

southern part of the study area to 52

gal/min on the Mogollon Rim and 48

gal/min on the Colorado Plateau. The

NWIS contains about 123 springs that

are within the study area, mainly on the

face of the Mogollon Rim and in the

canyons of major tributaries (fig. 3).

Discharges range from 0.05 to 18,620

gal/min (fig. 4).

Water Use

Ground water is the source of almost

all water for human uses except

recreation in the study area. Surface

water generally cannot be used because

water rights to surface flows are owned

by users downstream. About 30 water

companies deliver almost 3,500 acre feet

of water per year to commercial and

domestic customers in the area. There

are few irrigated lands in the study area.

The town of Payson accounts for about

half of the region’s water use. On the

basis of population projections, water

use by the year 2050 could range from

about 6,500 to more than 7,600 acre-feet

per year. None of the communities

within the study area, however, have an

adequate 100-year water supply,

according to the Arizona Department of

Water Resources. Some wells within the

study area go dry during periods of

drought. Restrictions on domestic water

use are frequently imposed in several

communities during dry spells. Some

wells have shown a decline in water

levels in recent years but it is not known

if this reflects a regional trend or is

instead related to climatic variability and

local hydrologic factors.

water is about 65 ft south of Payson,

about 86 ft in the mainly bedrock

aquifers on or at the base of the Mogollon

Rim, and about 105 ft on the Colorado

Plateau above the rim. Wells south of

Payson are considerably more productive

than those on the rim and on the

Colorado Plateau. Well discharges range
Water

source

Wells

Springs

Streamflow

Specific

conductance

(μS/cm)

Dissolved

solids

(mg/L)

Fluoride,

dissolved

(mg/L)

Arsenic,

dissolved

pH (mg/L)

Table 1. Values for selected water chemistry properties in Mogollon Highlands

[μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; N, number of analyses; R, range; Mn, mean; Md, median]

N R Mn/Md N R Mn/Md N R Mn/Md N R Mn/Md N R Mn/Md

7.40/

7.40

6.7–

8.9

383 1,241/

482

63–

97,700

1,165/ 197

750

55–

25,000

472 0.57/

0.35

339 0–4 .023/

0.11

.001–

.22

138

7.34/

7.36

89 517/

400

14– 3,230782/ 97

695

25– 4,660110 0.40/

0.20

0–

6.8

87 0.18/

.008

.001– 1.49

8.08/

8.20

5.58–

12.00

397 349/

197

40–

440

319/ 349

351

17–

800

406 0.92/

0.50

0–

3.3

323 .022/

0.13

.001–

.17

89

6.34– 8.20

For further information, contact:

John Parker

U.S. Geological Survey, WRD

520 North Park Avenue, Suite 221

Tucson, Arizona 85719-5035

E-mail: jtparker@usgs.gov or visit

home page http://az.water.usgs.gov

Feth, J.H., and Hem, J.D., 1963, Reconnaissance of

headwater springs in the Gila River drainage

basin, Arizona, U.S. Geological Survey

Water–Supply Paper, 1619–H, p. H1–H54.

Mayer, L., 1978, Evolution of the Mogollon Rim

in central Arizona: Tectonophysics, v. 61,

p. 49–62.

Richards, A.M., 1987, Gravity analysis of the Tonto

and Payson basins, central Arizona: Flagstaff,

Arizona, Northern Arizona University,

Master’s thesis, 162 p.

Southwest Ground-water Consultants, Inc. (SGC),

1998, Long-term management program of

the town of Payson’s water resources:

Phoenix, Arizona, Southwest Ground-water

Consultants, Inc., Report for Town of Payson,

61 p. + appendices.

Weir, G.W., and Beard, L.S., 1997, Preliminary

geologic map of the Strawberry quadrangle,

Yavapai, Gila, and Coconino Counties,

Arizona: U.S. Geological Survey Open–File

Report, 94–0265, 1 sheet.

Weisman, M.K., and Weir, G.W., 1990, Geologic

map of the Pine 7.5-minute quadrangle,

Coconino and Gila Counties, Arizona: U.S.

Geological Survey Miscellaneous Field

Studies Map, MF–2123, 1 sheet.

Wilson, E.D., Moore, R.T, and Peirce, H.W., 1959,

Geologic map of Gila County, Arizona,

Tucson, Arizona Bureau of Mines, 1 sheet.

Water Quality

Water quality within the study area is

variable. Well water tends to have high

concentrations of dissolved solids, and

individual water samples from wells and

springs have high concentrations of

arsenic and fluoride (table 1). U.S.

Environmental Protection Agency

(USEPA) Primary and Secondary

Drinking-Water Regulations include a

range of 6.5 to 8.5 for pH and a

maximum of 500 milligrams per liter

(mg/L) for dissolved solids. Concentrations of fluoride greater than 4.0

mg/L and of arsenic greater than 0.05

mg/L exceed USEPA Maximum

Contaminant Levels.

Remaining Questions

A number of questions are

fundamental to understanding the

hydrogeologic system of the Mogollon

Rim area. These include:

1. What is the recharge area for

springs and wells in the Paleozoic

sedimentary rocks?

2. Where is the ground-water divide

separating flow toward the rim from flow

moving toward the Little Colorado River?

3. What are the hydrogeologic characteristics of the Tertiary volcanic rocks

that cap some areas of the rim?

4. What are the rates of ground-water

flow from the recharge areas to springs

and wells in the upper Paleozoic aquifers

such as the Coconino Sandstone and

Upper Supai Formation?

5. Is there significant leakage from the

upper Paleozoic aquifers into underlying

sedimentary rocks and granite?

6. How sensitive are the water-bearing

zones within the Lower Supai Formation

and the Naco Formation to variability in

recharge? What are the hydrologic

characteristics of these formation? What

constitutes sustainable use in aquifers

within the Lower Supai and Naco

Formations?

7. What are the characteristics of the

regional ground-water flow system? Which

geologic formations are components of the

regional ground-water flow system,

where are the flow paths, and what is the

availability of water from that system?

8. Is the Payson granite recharged

significantly from overlying or adjacent

aquifers or is it recharged only from

precipitation? What constitutes sustainable use within the Payson granite?

9. What are the flow paths south of

Payson into the alluvial valley of the

Tonto Basin?

10. What are the hydrogeologic

characteristics of the Precambrian rocks

that form the Mazatzal Mountains and the

Sierra Ancha south of Payson?

11. How is human use affecting the

surface- and ground-water systems at

present, and how will future use affect

these systems in terms of water

availability and quality?

12. How are precipitation, surfacewater flows, and ground-water flows

linked or partitioned throughout the

hydrogeologic system?

Possible Approaches

The first year of the USGS study

mainly involved the collection and

compilation of existing data and the

development of a hydrogeologic data base.

These aspects of the study are expected to

continue throughout the life of the project,

however; the identification of data needs,

collection of new data, and evaluation,

synthesis, and analysis of data will

become increasingly important as the

project continues. Some of the approaches

that may be used to answer the questions

above and to develop conceptual and

interpretive models of the hydrogeologic

system in the study area include:

1. Synthesis and interpretation of

existing geologic mapping to develop a

preliminary three-dimensional geologic

framework of the study area.

2. Analysis of the spatial relations

among streams, springs, wells, and

geologic features, including unit

thickness, lithology, and dip, and

structural characteristics including faults,

fractures, and joints.

3. Analysis of the spatial variability in

aquifer characteristics and the relation of

such characteristics to geologic features.

—John T.C. Parker and Marilyn E. Flynn

References

4. Analysis of temporal relations

among various components of the

hydrologic system including precipitation,

streamflow, spring discharge, and groundwater levels using new and available data.

5. Hydrochemical analyses to determine ground-water flow paths and

residence times of ground-water within

different parts of the hydrogeologic system.

6. Integration of geologic and

hydrologic information to develop

conceptual and predictive models of the

regional hydrogeologic system.

7. Sensitivity analysis to identify those

components of the hydrogeologic system

that exert the greatest control over

regional ground-water flow to aid in

optimizing the collection of new data.

8. Development of a predictive model

of regional ground-water flow to

examine the effects of different waterresources development scenarios on the

hydrologic system.