Prepared in cooperation with the

Arizona Department of Water Resources and Mohave County, Arizona

Hydrogeologic Framework and Estimates of Groundwater 

Storage for the Hualapai Valley, Detrital Valley, and 

Sacramento Valley Basins, Mohave County, Arizona

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5275
FRONT COVER:

Desert in Mohave County, Arizona. Photo by Margot Truini.
Prepared in cooperation with the 

Arizona Department of Water Resources and Mohave County, Arizona

Hydrogeologic Framework and Estimates 

of Groundwater Storage for the Hualapai 

Valley, Detrital Valley, and Sacramento 

Valley Basins, Mohave County, Arizona

By Margot Truini, L. Sue Beard, Jeffrey Kennedy, and David W. Anning

Scientific Investigations Report 2012–5275

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia 2013

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Suggested citation:

Truini, M., Beard, L.S., Kennedy, J., Anning, D.W., 2013, Hydrogeologic framework and estimates of groundwater storage for the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, Arizona: U.S. Geological 

Survey Scientific Investigations Report 2012–5275, 47 p.

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

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iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Study Area..............................................................................................................................................3

Previous Investigations........................................................................................................................5

Acknowledgments................................................................................................................................5

Approach ........................................................................................................................................................5

 Hydrogeologic Framework Components .........................................................................................5

Geologic Setting...........................................................................................................................6

Regional Geologic History..........................................................................................................6

Geologic Description of the Valley Basins .............................................................................9

Hualapai Valley Basin ........................................................................................................9

Detrital Valley Basin .........................................................................................................11

Sacramento Valley Basin ................................................................................................12

Well-Log Lithologic Data ..........................................................................................................13

Basin Geometry Model .............................................................................................................13

Previous Subsurface-Geometry Studies ......................................................................13

Basin Gravity Anomaly ....................................................................................................16

Construction of the Basin Geometry Model.................................................................16

Interpreted Resistivity Profiles ................................................................................................18

Hydrogeologic Framework ........................................................................................................................26

Hualapai Valley Basin ........................................................................................................................26

Kingman Subbasin.....................................................................................................................26

Hualapai Subbasin.....................................................................................................................26

Southern Gregg Subbasin ........................................................................................................29

Detrital Valley Basin ...........................................................................................................................29

Northern Detrital Subbasin ......................................................................................................29

Central Detrital Subbasin .........................................................................................................29

Southern Detrital Subbasin......................................................................................................29

Sacramento Valley Basin ..................................................................................................................34

Chloride Subbasin......................................................................................................................34

Golden Valley Subbasin ............................................................................................................34

Dutch Flat Subbasin .................................................................................................................34

Groundwater Storage..................................................................................................................................38

Construction of the Groundwater Storage Model.........................................................................38

Groundwater Storage Estimates......................................................................................................42

Summary........................................................................................................................................................42

References Cited..........................................................................................................................................44
iv

Figures

1. Mohave County, northwest Arizona, showing physiography and location of the study area 

in the Hualapai Valley, Detrital Valley, and Sacramento Valley basins ...............................2

2. Mohave County, northwest Arizona, showing the physiography and distribution of precipitation ...............................................................................................................................................4

3. Mohave County, northwest Arizona, showing surface geology and structure in Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins ...........................................................8

4. Schematic cross-sections showing extensional-basin evolution, structural and stratigraphic relations between older and younger basin fill, volcanic rocks, and older and 

younger surficial deposits.........................................................................................................10

5. Photographs showing exposed sedimentary deposits of active playa deposits in Red Lake 

playa..............................................................................................................................................11

6. Mohave County, northwest Arizona, showing location of wells into volcanic and crystalline 

rocks .............................................................................................................................................14

7. Mohave County, northwest Arizona, showing location of wells in the Arizona Department 

of Water Resources database (Wells55) and from the U.S. Geological Survey Groundwater Information Systems database. ....................................................................................15

8. Basin gravity anomaly in Mohave County, northwest Arizona...................................................17

9. Basin geometry model showing subbasins and estimated depth in the Hualapai Valley, 

Detrital Valley, and Sacramento Valley Basins, Mohave County, northwestern Arizona

 ..............................................................................................................................................19

10. Histogram of difference in bedrock depth between the basin geometry model and well logs

................................................................................................................................................20

11. Mohave County, northwest Arizona, showing location of GEOTEM surveys in the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins. ........................................................21

12. Mohave County, northwest Arizona, showing perspective view to the northeast in the 

Golden Valley subbasin, Sacramento Valley basin, with example of where the basin 

geometry model did not match GEOTEM profiles and well-log lithologic interpretation 

of boundary between volcanic bedrock and basin fill .........................................................23

13. Mohave County, northwest Arizona, showing perspective view to the northeast in the 

Golden Valley subbasin of the Sacramento Valley basin, with interpretation of high 

transient electromagnetic resistivity values >100 Ω•m .......................................................24

14. Mohave County, northwest Arizona, showing perspective view to northeast in the Golden 

Valley subbasin, Sacramento Valley Basin, with example of the uninterpreted resistivity profile.......................................................................................................................................25

15. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted and interpreted resistivity from GEOTEM profiles in northern part of the Kingman subbasin of the Hualapai Valley basin............................................................................27

16. Mohave County, northwest Arizona, showing perspective view to northwest, of uninterpreted and interpreted resistivity from GEOTEM profiles in Hualapai subbasin, Hualapai Valley basin ...........................................................................................................................28

17. Mohave County, northwest Arizona, showing perspective view to the northwest of uninterpreted and interpreted resistivity from GEOTEM profiles in southern Gregg subbasin, 

Hualapai Valley basin.................................................................................................................30

18. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted and interpreted resistivity from GEOTEM profiles in northern Detrital subbasin, 

Detrital Valley basin....................................................................................................................31

19. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted and interpreted resistivity from GEOTEM profiles in the central subbasin in 
v

Detrital Valley basin....................................................................................................................32

20. Mohave County, northwest Arizona, perspective view showing vertical changes in resistivity with depth from unsaturated to saturated basin fill on GEOTEM profile D8 overlain 

on the basin geometry model in the central Detrital subbasin of the Detrital Valley 

basin..............................................................................................................................................33

21. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted resistivity and interpreted resistivity from GEOTEM profiles in the southern 

Detrital subbasin in Detrital Valley basin................................................................................35

22. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted and interpreted resistivity for GEOTEM profiles in the Chloride subbasin of the 

Sacramento Valley basin...........................................................................................................36

23. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted resistivity and interpreted resistivity for GEOTEM profiles in Golden Valley 

subbasin of the Sacramento Valley basin ..............................................................................37

24. Mohave County, northwest Arizona, showing perspective view to the northeast of uninterpreted and interpreted resistivity from GEOTEM profiles in the Dutch Flat subbasin of 

the Sacramento Valley basin....................................................................................................39

25. Mohave County, northwest Arizona, showing areas of modeled saturated sediments delineating hydrogeologic unit areas in the Hualapai Valley, Detrital Valley, and Sacramento 

Valley basins................................................................................................................................41

Tables

1. Geologic units and correlation to lithologic description and depositional setting in the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, Arizona.....7

2. Generalized grouping of lithology from well logs ...........................................................................12

3. Relation between lithology and approximate ranges in resistivity values .................................22

4. Estimated groundwater storage in basin-fill aquifers to 400 meters below land surface in 

the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, 

Arizona..........................................................................................................................................43
vi

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

meter (m) 1.094 yard (yd) 

Volume

liter (L) 33.82 ounce, fluid (fl.oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

cubic meter (m3

) 264.2 gallon (gal)

cubic decimeter (dm3

) 0.2642 gallon (gal)

cubic meter (m3

) 0.0002642 million gallons (Mgal)

cubic centimeter (cm3

) 0.06102 cubic inch (in3)

cubic decimeter (dm3

) 61.02 cubic inch (in3)

liter (L) 61.02 cubic inch (in3

)

cubic meter (m3

) 35.31 cubic foot (ft3)

cubic meter (m3

) 1.308 cubic yard (yd3)

cubic kilometer (km3

) 0.2399 cubic mile (mi3)

cubic meter (m3

) 0.0008107 acre-foot (acre-ft)
Abstract

We have investigated the hydrogeology of the Hualapai Valley, Detrital Valley, and Sacramento Valley basins of 

Mohave County in northwestern Arizona to develop a better 

understanding of groundwater storage within the basin fill 

aquifers. In our investigation we used geologic maps, well-log 

data, and geophysical surveys to delineate the sedimentary 

textures and lithology of the basin fill. We used gravity data 

to construct a basin geometry model that defines smaller 

subbasins within the larger basins, and airborne transientelectromagnetic modeled results along with well-log lithology 

data to infer the subsurface distribution of basin fill within the 

subbasins. Hydrogeologic units (HGUs) are delineated within 

the subbasins on the basis of the inferred lithology of saturated 

basin fill. We used the extent and size of HGUs to estimate 

groundwater storage to depths of 400 meters (m; 1,312 feet, ft) 

below land surface (bls).

The basin geometry model for the Hualapai Valley basin 

consists of three subbasins: the Kingman, Hualapai, and 

southern Gregg subbasins. In the Kingman subbasin, which 

is estimated to be 1,200 m (3,937 ft) deep, saturated basin fill 

consists of a mixture of fine- to coarse-grained sedimentary 

deposits. The Hualapai subbasin, which is the largest of the 

subbasins, contains a thick halite body from about 400 m to 

about 4,300 m (14,107 ft) bls. Saturated basin fill overlying 

the salt body consists predominately of fine-grained older 

playa deposits. In the southern Gregg subbasin, which is 

estimated to be 1,400 m (4,593 ft) deep, saturated basin fill 

is interpreted to consist primarily of fine- to coarse-grained 

sedimentary deposits. Groundwater storage to 400 m bls in the 

Hualapai Valley basin is estimated to be 14.1 cubic kilometers 

(km3

; 11.4 million acre-feet).

The basin geometry model for the Detrital Valley basin 

consists of three subbasins: northern Detrital, central Detrital, and southern Detrital subbasins. The northern and central 

Detrital subbasins are characterized by a predominance of 

playa evaporite and fine-grained clastic deposits; evaporite 

deposits in the northern Detrital subbasin include halite. The 

northern Detrital subbasin is estimated to be 600 m (1,968 ft)

deep and the middle Detrital subbasin is estimated to be 700 m 

(2,296 ft) deep. The southern Detrital subbasin, which is estimated to be 1,500 m (4,921 ft) deep, is characterized by a mixture of fine- to coarse-grained basin fill deposits. Groundwater 

storage to 400 m bls in the Detrital Valley basin is estimated to 

be 9.8 km3

 (7.9 million acre-feet).

The basin geometry model for the Sacramento Valley 

basin consists of three subbasins: the Chloride, Golden Valley, and Dutch Flat subbasins. The Chloride subbasin, which 

is estimated to be 900 m (2,952 ft) deep, is characterized by 

fine- to coarse-grained basin fill deposits. In the Golden Valley 

subbasin, which is elongated north-south, and is estimated 

to be 1,300 m (4,265 ft) deep, basin fill includes fine-grained 

sedimentary deposits overlain by coarse-grained sedimentary 

deposits in much of the subbasin. The Dutch Flat subbasin is 

estimated to be 2,600 m (8,530 ft) deep, and well-log lithologic data suggest that the basin fill consists of interlayers of 

gravel, sand, and clay. Groundwater storage to 400 m bls in 

the Sacramento Valley basin is estimated to be 35.1 km3

 (28.4 

million acre-feet).

Introduction

Basin fill aquifers are the primary source of groundwater in the Hualapai Valley, Detrital Valley, and Sacramento 

Valley basins of northwest Arizona for domestic, mining, and 

industrial use (fig. 1). Groundwater declines are not occurring in most areas (Anning and others, 2007), although in 

some areas extensive groundwater fluctuations were observed 

between 1943 and 2006, and in other areas there were steady 

groundwater declines (Anning and others, 2007). As in many 

parts of the western United States, population growth in these 

valleys has been substantial. For example, from 2000 to 2010 

the population of Kingman grew from 20,069 to 28,068—an 

increase of 39.9 percent (U.S. Census Bureau, 2011)—and 

the population of Mohave County increased by 29.1 percent. 

Recently proposed developments for approximately 200,000 

new houses and condominiums in all three basins, and groundwater use for alternative energy in a proposed solar corridor 

Hydrogeologic Framework and Estimates of Groundwater 

Storage for Hualapai Valley, Detrital Valley, and 

Sacramento Valley Basins, Mohave County, Arizona

By Margot Truini, L. Sue Beard, Jeffrey Kennedy, and David W. Anning
2 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Truxton Wash

Detrital Wash

Sacramento Wash

Frees Wash

Grasshopper

Junction

Berry

Yucca

Topock

Walapai

Kingman

Griffith

Chloride

Goldroad

Franconia

Hackberry

White Hills

Santa Claus

Golden Valley

Dolan SpringsH U A L A PA I VA L L E Y B A S I N

S A C R A M E N T O VA L L E Y B A S I N

D E T R I TA L VA L L E Y B A S I N

BLACK 

MOUNTAINS

BLACK

MOUNTAINS

HUALAPAI

MOUNTAINS

M O U N TA I N S

M O H AV E

M c C R A K E N

M O U N TA I N S

CERBAT MOUNTAINS

GRAND

WASH

CLIFFS

WHITE

HILLS

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

30’

35o

34o30’

Groundwater

divide

Temple

Bar

EXPLANATION

Basin boundary

0 25 50 KILOMETERS

0 20 40 MILES

M U S I C M O U N TA I N S

MOUNT

TIPTON

P E A C O C K 

M O U N TA I N S

Silver 

Creek 

Caldera HUALAPAI

MOUNTAIN

BUCK

MOUNTAIN

LONG 

MOUNTAIN

Base From U. S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Major roads

"

95

£¤93

66

66

§ ̈¦40

"

Meadview

Kingman Flagstaff

Tucson

Phoenix 

ARIZONA

Northwest basins Rural Watershed Initiative study area

Mohave 

County

Hualapai Valley

Detrital

Valley

Sacramento

Valley

Figure 1. Mohave County, northwest Arizona, 

showing physiography and location of the study 

area in the Hualapai Valley, Detrital Valley, and 

Sacramento Valley basins.
Introduction 3

have raised concerns about groundwater availability and storage from water managers, Mohave County, and the Arizona 

Department of Water Resources (ADWR; Kevin Davidson, 

Planner II, written commun., 2008; Las Vegas Review-Journal, 

http://www.lvrj.com/business/44775192.html).

The ADWR recognized the need to conduct a comprehensive scientific study of the basin fill aquifers to help growing 

communities within Mohave County sustainably manage their 

groundwater resources. In 2005, the U.S. Geological Survey 

(USGS), in cooperation with the ADWR, began a regional 

study of the Hualapai Valley, Detrital Valley, and Sacramento 

Valley basins in northwestern Arizona to characterize the 

hydrogeology and estimate groundwater storage in the upper 

400 m of the valley basins. That study is part of the Rural 

Watershed Initiative (RWI), a program established by the State 

of Arizona that is managed by the ADWR. The RWI focuses 

on addressing water-supply issues in rural areas and encourages participation from local partnerships. RWI projects and 

publications describing the hydrogeology have been completed in the middle San Pedro, and upper and middle Verde 

River watersheds, on the Coconino Plateau, and in the Mogollon Highlands (Parker and others, 2005; Blasch and others 

2006; Bills and others, 2007; Dickinson and others, 2010).

Purpose and Scope

The purpose of this report is to achieve a better understanding of the hydrogeologic framework of, and to estimate 

groundwater storage in the Hualapai Valley, Detrital Valley, 

and Sacramento Valley basins of northwestern Arizona. A 

hydrogeologic framework is a conceptual model that describes 

how the bedrock and basin fill influence the movement, storage, and quality of groundwater within each valley basin.

The scope of the present study involved analysis of 

recent and historical geophysical, water-level, and geologic 

data to characterize the alluvial deposits within the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins. Subsurface lithology was inferred from airborne transient electromagnetic (TEM) resistivity profiles to a depth of 400 meters 

(m) below land surface (bls), and a basin geometry model 

was constructed from relative gravity data used to characterize the basin geometry and overlying basin fill. Revised geologic data (Beard and others, 2011) provide a more detailed 

map of the surface geology and structure. Water-level data 

(Anning and others, 2007) were used to define the top of the 

groundwater surface. Hydrogeologic units (HGUs) of saturated fine-grained, coarse-grained, or undifferentiated basin 

fill from inferred lithology were used to estimate groundwater 

storage to 400 m bls, which correlates to the depth of the 

resistivity profiles.

Study Area

The Hualapai Valley, Detrital Valley, and Sacramento Valley basins are broad, intermountain desert basins in Mohave 

County, northwestern Arizona, that are home to residents 

in Kingman, Golden Valley, Meadview, Dolan Springs, and 

several other rural communities (fig. 1). The spatial extent 

of these valley basins is outlined by the groundwater basin 

boundaries defined by the ADWR. Valley-floor elevations 

range from about 150 m above mean sea level at the mouth of 

Sacramento Wash near Topock to about 1,060 m above mean 

sea level near Kingman. Mountain crests rise to 2,179 m above 

mean sea level at Mount Tipton in the Cerbat Mountains and 

to 2,565 m above mean sea level at Hualapai Mountain. All 

surface drainages in the three valley basins are ephemeral, 

flowing only during significant precipitation events.

The climate of the valley basins is semiarid to arid with 

hot summers and mild winters. Maximum daily temperatures 

on the valley floors typically range from 32 degrees Celcius 

(°C) to 43.3 °C during the summer, and from 10 to 21 °C during 

the winter (Western Regional Climate Center, 2005). Annual 

precipitation on the valley floors ranges from about 12.7 to 20.3 

centimeters (cm); (fig. 2; Western Regional Climate Center, 

2005). The valley floors generally are covered with sparse 

desert vegetation, owing to the hot temperatures and limited 

precipitation. Shrubs and trees cover mountain slopes and peaks 

in the higher elevations, where temperatures are cooler and 

precipitation is greater. Annual precipitation in the mountains 

ranges from about 25.7 to 38.1 cm. Groundwater recharge primarily occurs along the mountain fronts, and groundwater flows 

from those areas toward the center of the valley basins and then 

along the basin axis to where it discharges at the north end of 

the Hualapai Valley and Detrital Valley basins into Lake Mead, 

or at the southwestern edge of Sacramento Valley basin into the 

Colorado River (Anning and others, 2007).

The Hualapai Valley basin comprises an area of about 

2,000 square kilometers (km2

) and is bordered to the east by 

the Music and Peacock Mountains and the Grand Wash Cliffs, 

to the south by the Hualapai Mountains, to the west by the 

Cerbat Mountains and White Hills, and to the north by Lake 

Mead (fig. 1). The city of Kingman, which is located in the 

southwestern part of the Hualapai Valley basin and the northeastern part of the Sacramento Valley basin, relies completely 

on groundwater from the Hualapai Valley basin. The floor of 

the Hualapai Valley basin generally slopes north, and groundwater discharges into Lake Mead (Remick, 1981; Anning and 

others, 2007). Surface-water drainage in the Hualapai Valley 

basin is mostly internal. Truxton Wash is the principal ephemeral stream in the area and storm runoff events during the 

spring and summer drain into Red Lake playa. Hualapai Wash 

has ephemeral flows north of Red Lake and drains into Lake 

Mead. Smaller ephemeral streams flow into the valley basin 

from the mountains during storm runoff events in spring and 

summer, but most of the runoff is lost to evaporation and does 

not contribute to the larger washes (Remick, 1981).

The Detrital Valley basin comprises an area of about 

1,400 km2

 and is bordered to the east by the White Hills and 

Cerbat Mountains, to the west by the Black Mountains, to 

the north by Lake Mead, and to the south by a topographic 

divide separating it from Sacramento Valley basin (fig. 1). 
4 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Truxton Wash

Detrital Wash

Sacramento Wash

Frees Wash

Yucca

Topock

Kingman

Griffith

Chloride

Hackberry

White Hills

Dolan Springs

Golden Valley

0 25 50 KILOMETERS

0 20 40 MILES

H U A L A PA I VA L L E Y B A S I N

S A C R A M E N T O VA L L E Y B A S I N

D E T R I TA L VA L L E Y B A S I N

114o30’ 114o

36o

30’

35o

34o30’

EXPLANATION

Average precipitation per year, in centimeters (inches)

Base from U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

12.7–15.2 (5–6)

15.5–20.3 (6.1–8)

20.6–25.4 (8.1–10)

25.7–30.5 (10.1–12)

30.7–35.6 (12.1–14)

35.8–38.1 (14.1–15)

Basin boundary

Figure 2. Mohave County, northwest Arizona, showing 

the physiography and distribution of precipitation. 
Approach 5

The towns of Temple Bar, Dolan Springs, White Hills, and 

Grasshopper Junction, located at the base of the White Hills 

and Cerbat Mountains, are the primary water users in the area. 

The floor of Detrital Valley basin generally slopes to the north 

and groundwater drains into Lake Mead (Anning and others, 

2007). Detrital Wash is the largest ephemeral stream in the 

area and flows northward into Lake Mead.

The Sacramento Valley basin comprises an area of about 

2,600 km2, bounded by the Cerbat and Hualapai Mountains 

to the east, by the Mohave and McCracken Mountains to the 

south, and by the Black Mountains to the west. The towns of 

Golden Valley, Chloride, Santa Claus, Harris, Griffith, and 

Topock are the primary water users in the basin. Open-pit 

copper, molybdenum, and silver mining in Golden Valley have 

also been large water users in the past. Sacramento Wash, the 

main ephemeral stream, originates north of Golden Valley, 

flows from north to south, and discharges into the Colorado 

River at Topock. Smaller ephemeral streams originating in 

the mountains flow into Sacramento Wash. The valley floor of 

the northern and central parts of the Sacramento Valley basin 

slopes south, and groundwater drains from the north into the 

Colorado River near Topock. The southern part of the Sacramento Valley basin slopes north or west and surface-water 

drains northward into Sacramento Wash or westward to the 

Colorado River (fig. 1).

Previous Investigations

In 1964, the USGS, in cooperation with the Arizona State 

Land Department, compiled data on the geology and water 

resources of the Hualapai and Sacramento Valleys (Gillespie 

and others, 1966). Using data from a study completed in 

1966, Gillespie and Bentley (1971) indicated that the older 

alluvium and younger volcanic rocks are important aquifers in 

the Hualapai and Sacramento Valleys. From 1981 to 1991, the 

ADWR completed a series of studies on groundwater conditions and water quality in the Hualapai Valley, Detrital Valley, 

and Sacramento Valley basins (Remick, 1981; Dillenberg, 

1987; Rascona, 1991). Anning and others (2007) completed 

a study of groundwater occurrence and movement of groundwater in 2006 and water-level changes within the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins. Langenheim and others (2010) investigated gravity and magnetic 

anomalies in the northern Colorado River extensional corridor 

and the Lake Mead area. Local gravity studies were previously 

completed in the Hualapai Valley, Detrital Valley, and Sacramento Valley basins by the ADWR (Mason and others, 2007; 

Conway and Ivanich, 2008; Ivanich and Conway, 2009).

Acknowledgments

We thank the many landowners in the Hualapai Valley, 

Detrital Valley, and Sacramento Valley basins that permitted land access for the purpose of acquiring data. This study 

would lack essential data without their help and support. We 

are grateful to Leslie Graser, Bill Remick, Tom Whitmer, John 

Fortune, Brian Conway, and Paul A. Ivanich, formerly and 

presently of the ADWR, for their technical guidance throughout this study. We also thank our USGS colleagues Marilyn 

Flynn, Jamie P. Macy, Donald R. Pool, Jesse Dickinson, 

Tracey Felger, and Zachary Anderson for providing scientific 

and technical expertise.

Approach 

The approach of this study was first to identify, acquire, 

and compile the geologic, geophysical, and water-level datasets needed to conceptualize the hydrogeologic framework of 

the Hualapai Valley, Detrital Valley, and Sacramento Valley 

basins. These same datasets and the conceptual understanding 

provided by the hydrogeologic framework were then used to 

estimate groundwater storage. The geologic maps (Beard and 

others, 2011) and cross sections compiled and synthesized for 

this study, as well-log and lithologic data, formed a foundation 

of geologic information for constructing the hydrogeologic 

framework. Results of this analysis are included in the section 

below entitled “Hydrogeologic Framework Components.”

Geophysical surveys of relative gravity that included 

data collected by the ADWR in 2006 were used to construct 

basin geometry models that described basin fill thickness and 

defined subbasins. Geophysical surveys of airborne TEM data, 

which were collected as part of this study to provide lithologic 

information along selected basinwide transects, provided 

information to a depth of about 400 m bls. Geologic information from maps and well logs helped constrain both the basin 

geometry model and lithologic interpretations of the airborne 

TEM data. Hydrologic maps by Anning and others (2007) and 

well logs provided water-level data for each basin and helped 

define where basin fill is saturated or unsaturated. Results of 

this data collection and compilation are discussed below.

The groundwater storage model used information from 

the hydrogeologic framework for each valley basin to a depth 

of 400 m bls. Basin fill lithologic units were delineated in 

the hydrogeologic framework and were binned into one of 

four generalized hydrogeologic units (HGUs), which were 

defined for the purpose of estimating groundwater storage and 

constructing groundwater-flow models. Information from 

the hydrogeologic framework defined the lateral and vertical 

extents of the HGUs, and with estimates of specific yields for 

each HGU, groundwater storage estimates were determined. 

The results of this effort are reported in the section entitled 

“Groundwater Storage.”

 Hydrogeologic Framework Components

The hydrogeologic framework for the Hualapai Valley, 

Detrital Valley, and Sacramento Valley basins was constructed 

through analysis of new and existing geologic, geophysical, 

and water-level information. An extensive literature search 
6 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

of published data and information was used to develop initial 

conceptual models and identify information needs. Preexisting 

data and information are available from the State of Arizona 

geologic map (Richard and others, 2000) and from other similar hydrogeologic studies in other parts of Arizona (Brown 

and others, 1966; Freethey, 1982; Pool and Coes, 1999; Coes 

and Pool, 2007; Pool and Dickinson, 2007; Dickinson and 

others, 2010).

Components required to construct the hydrogeologic 

framework included geophysical data for modeling subsurface 

geology that affects groundwater flow, depth to bedrock and 

thickness of saturated basin fill, and extent and depth of silt, 

clay, and evaporite layers within coarse-grained sedimentary 

deposits. To address these data and information needs, new 

data collection included compilation of previous geologic 

mapping (Beard and others, 2011), relative gravity surveys 

(Mason and others, 2007; Conway and Ivanich, 2008; Ivanich 

and Conway, 2009), airborne TEM resistivity profiles, and 

examination of lithologic information from well logs.

A 1:250,000-scale geologic map covering the Detrital 

Valley, Hualapai Valley, and Sacramento Valley basins of 

northwestern Arizona was published by Beard and others 

(2011) for the purpose of improving understanding of the 

geology and hydrogeology of the study area (fig. 3). Their 

map, which was compiled from existing geologic mapping 

augmented by digital photogeologic reconnaissance mapping, provides significantly more detailed geology than the 

1:1,000,000-scale geologic map of Arizona (Richards and others, 2000) with regard to the accuracy of unit contacts, number, type, and location of faults, and details of Neogene and 

Quaternary deposits. It also provides a detailed summary of 

the geologic units, setting, and history of the Hualapai Valley, 

Detrital Valley, and Sacramento Valley basins. The geologic 

units and geologic map from that report are generalized in 

figures 3 and 4 and briefly summarized below.

Geophysical data used for mapping subsurface lithology 

and structure included relative gravity measurements and airborne TEM resistivity surveys. Relative gravity measurements 

were used to estimate depth to the top of bedrock, thickness of 

basin fill, and to construct a basin geometry model based on 

differences in the densities of bedrock and basin fill (Telford 

and others, 1976). The basin geometry model presented in this 

study delineates nine subbasins in the three valley basins, discussed in more detail in the subsection below entitled “Basin 

Geometry Model.” The geometry of the subbasins is important 

because it influences the vertical and lateral distribution of 

basin fill determining groundwater storage.

An electrical current can flow more easily through saturated fine- and coarse-grained basin fill and (or) evaporites 

versus unsaturated fine- and coarse-grained basin fill and (or) 

evaporites. Electrical-resistivity data obtained from airborne 

TEM were used to delineate areas of crystalline and volcanic 

bedrock, distinguish saturated silt and clay from saturated sand 

and gravel, and identify the lateral extent of thick sequences 

of gypsum/anhydrite and halite in the northern parts of the 

Hualapai Valley and Detrital Valley basins. Well-log lithologic 

data and TEM resistivity profiles of the valley floors, presented in the subsections below entitled “Well-Log Lithologic 

Data” and “Interpreted Resistivity Profiles” respectively, were 

used to help classify the basin fill into lithologic units.

Geologic Setting

The study area (fig. 1) is mostly in the Basin and Range 

Physiographic Province (Fenneman, 1931), which was formed 

by extensional faulting during the Miocene. The study area is 

underlain by crystalline Proterozoic rocks, either exposed at 

the surface or overlain by thin to thick sequences of Miocene 

volcanic and sedimentary rocks. Lower Paleozoic strata are 

exposed only along the Colorado Plateau's margin at the east 

edge of the study area. The fault-bounded ranges are separated 

by extensional basins that underlie the three valley basins and 

form the subbasins identified in the basin geometry section 

discussed later in this report. Pliocene through Holocene surficial deposits blanket the slopes and surfaces of the valleys. 

This summary provides a broad overview of the study area’s 

geology, whereas Beard and others (2011) discuss in more 

detail the regional geologic history and provide descriptions of 

the geologic structures and formations.

The map by Beard and others (2011) provides an understanding of the processes and formation of geologic structures, depositional environments, and associated sedimentary 

sequences in the study area. Such an understanding is needed 

for spatial extrapolation of lithology from areas with data and 

known conditions into areas that lack such data and require 

estimation of the sedimentary lithology. Beard and others's 

(2011) results are summarized below in the next two parts of 

this subsection.

Regional Geologic History

Proterozoic crystalline basement rocks include metamorphic gneiss and schist deformed about 1.73–1.68 Ga and later 

intruded by granite about 1.4 Ga (table 1). Paleozoic sedimentary rocks were deposited on an unconformity in the basement 

rocks. During late Cretaceous and Paleocene (Laramide) time, 

the study area was locally intruded by late Cretaceous plutons 

and uplifted, exposing basement rocks in the core of the uplift. 

Post-Laramide erosion removed Paleozoic and Mesozoic sedimentary deposits off the uplift (Bohannon, 1984) and created a 

beveled erosional surface cut on lower Paleozoic rocks of the 

western Colorado Plateau's margin. The erosion was accompanied by the formation of large paleovalleys that drained 

northeastward off the uplift and onto the Colorado Plateau 

(Young, 2001), including a paleovalley between the Cerbat 

and Hualapai Mountains (Beard and others, 2011) where the 

city of Kingman is located (fig. 3).

Cenozoic geologic processes in the study area began with 

volcanism and plutonism at about 20 Ma, followed by crustal 

extension and continued volcanism and plutonism (fig. 4; 

Faulds, 1995). The main extensional event started about 16 Ma 
Approach 7

Table 1. Geologic units and correlation to lithologic description and depositional setting in the Hualapai Valley, Detrital Valley, and 

Sacramento Valley basins, Mohave County, Arizona. 

Geologic age Geologic unit (map 

units defined on 

figures 3 and 4)

Lithologic description Depositional Setting

Geologic epoch Geologic age Rock type Grain size Basin fill

Surface deposits (10s of meters thick)

Surficial deposits

Holocene 0 to ~12 ka Valley-axis alluvialwash deposits (Qw)

Silt, sand, some 

gravel

Medium, 

coarse

Alluvial fan/alluvial 

plain

Holocene to late 

Pleistocene 0 to ~780 ka

Younger and older 

playa and eolian sand 

deposits (Qp, Qpo, 

Qe)

Clay, silt, sand Fine Lacustrine/playa

Holocene to 

Pleistocene 0 to ~2.5 Ma

Younger (Qa, Qty, 

Qto) and older (QTa) 

alluvial deposits

Sand, gravel, 

boulders

Medium, 

coarse

Alluvial fan/alluvial 

plain

Subsurface deposits (100s of meters to several kilometers thick)

Younger basin fill

Pliocene ~2.5–5 Ma Bouse Formation (Tb) Clay, silt, sand 

(some gravel) Fine Shoreline/eolian

Pliocene to upper Miocene 3.6–5.5 Ma Younger basin-fill 

deposits (Tsy)

Clay, silt, sand, 

halite, gypsum/

anhydrite

Fine Lacustrine/playa

Upper to Middle 

Miocene, 6–10 Ma Younger basin-fill deposits (Tsy)

Sand, gravel, 

boulders

Medium, 

coarse

Alluvial fan/alluvial 

plain

Upper Miocene 6–10 Ma Hualapai Limestone 

(Th) Limestone not applicable Lacustrine/playa

Subsurface deposits tilted and faulted; locally up to 1–3 kilometers thick

Older basin fill Pliocene to upper Miocene 6–10 Ma Older basin fill (Tso) Sand, gravel, 

boulders

Medium, 

coarse not applicable

Bedrock

Bedrock

Lower Miocene 

to Paleoproterozoic

>10 Ma to 

~1.8 Ga

Consolidated rocks 

(Tv, TXu)

Volcanic rocks, 

and granite and 

metamorphic 

rocks

not applicable not applicable
8 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Siliciclastic rocks and carbonate 

Older alluvial-fan deposits

Younger alluvial-fan deposits

Eolian sand

Playa deposits

Older playa deposits

Older Truxton Wash alluvial-fan deposits

Younger Truxton Wash alluvial-fan deposits

Valley-axial wash alluvium

Bouse Formation

Hualapai Limestone

Conglomerate, sandstone, and breccia

Clastic deposits and 

 evaporite 

Mafic and felsic volcanic rocks and ash-flow tuff

Cretaceous and Tertiary granite

Proterozoic granite and gneiss

Water

Younger surficial deposits 

 (Pleistocene and Holocene)

Younger basin-fill deposits (late Miocene)

Older basin-fill deposits (middle Miocene)

Volcanic rocks (middle and late Miocene) 

Sedimentary rocks (early Paleozoic)

Crystalline basement rocks 

 (Proterozoic, Cretaceous, and Miocene)

Older surficial deposits (Pliocene and Pleistocene)

Tv

Tso

Tsy

Pzu

TXu

Tb

Th

QTa

Qw

Qa

Qe

Qp

Qpo

Qto

Qty

?

?

?

CF

SGWF

KF

BMF

BuMF

NGWF

114°30'W

114°0'

114°0'

36°0'N 36°0'

35°30'

35°30'

35°0'

34°30'

DFF

Normal fault, bar and ball on downthrown side

Inferred from geophysical data; 

 dash indicates higher degree of uncertainty,

 bar indicates inferred downthrown side

Low-angle normal fault, hatchures on downthrown side 

Faults

EXPLANATION

0 25 KILOMETERS

0 20 MILES Base from U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Modified from Beard and others, 2011

Figure 3. Mohave County, northwest Arizona, showing surface geology and structure in Hualapai Valley, Detrital Valley, and 

Sacramento Valley basins. Mapped faults are shown in black; black hachured lines are low-angle detachment faults. Faults inferred 

from basin geometry model gravity model and transient electromagnetic data shown in red. Dashed red lines denote higher degree of 

uncertainty (BGF, Blind Goddess Fault; BMF, Black Mountain Fault; BuMF, Buck Mountain Fault; CF, Chloride Fault; DDF, Dutch Flat Fault; 

KF, Kingman Fault; NGWF, northern section of the Grand Wash Fault; SGWF, southern section of the Grand Wash Fault).
Approach 9

and peaked about 15 to 13 Ma; it affected most of the study 

area, from north of Goldroad (fig. 1) to Lake Mead and from 

Sacramento Wash southward, and resulted in highly tilted fault 

blocks bounded by north-northwest-striking faults. The extensional basins that formed during this event filled with middle 

Miocene volcanic rocks and older sedimentary deposits (fig. 

4A). In the northern White Hills the basins are predominately 

filled with clastic deposits, and in the southwest White Hills 

and the Black Mountains the older basin fill is predominately 

volcanic rocks (Beard and others, 2011).

Later (~13–8 Ma) extensional faulting formed the subbasins, typically bounded by one or more northerly-striking 

normal faults that underlie the modern valleys (fig. 4B; Beard 

and others, 2011). These subbasins were internally drained and 

filled by the late Miocene sediment deposited in lacustrine/

playa, shoreline, alluvial-fan, and alluvial-plain settings. The 

lacustrine late Miocene Hualapai Limestone was deposited 

at the north end of Hualapai Valley, and deltaic sedimentary 

deposits of the late Miocene Bouse Formation were deposited 

along the Colorado River at the west end of the Sacramento 

Valley. In contrast to the older rocks, these deposits are mostly 

flat-lying or mildly tilted. Isolated late Miocene basalt flows 

overlie younger sedimentary deposits on the west side of 

the Detrital Valley and on the northeast flank of the Mohave 

Mountains. After integration of the Colorado River drainage 

ended interior basin deposition, the subbasins were overlapped 

and mostly buried by older Pliocene and Pleistocene surficial 

deposits, and Pleistocene and Holocene alluvial and playa 

deposits that form the smooth floors of the three valley basins 

(figs. 3, 4C). At the distal ends of the three valley basins, the 

younger sedimentary deposits, the Hualapai Limestone, and 

the Bouse Formation are eroded and exposed by tributaries 

that drain into Lake Mead and the Colorado River; these units 

are not exposed elsewhere in the valley basins.

Geologic Description of the Valley Basins 

Bedrock, exposed in the mountain ranges and underlying 

Miocene sedimentary deposits in the three valley basins, is 

composed primarily of Proterozoic metamorphic and granitic 

rocks, locally intruded by small Late Cretaceous and Miocene 

plutonic rocks. Together, these rocks form a crystalline basement complex and are the lowermost barrier to movement of 

groundwater in the study area (Gillespie and Bentley, 1971). 

The crystalline rocks do not yield much water, except in 

highly weathered zones and along fractures.

In this study, we focus on the hydrogeology of the sedimentary deposits and overlying basin fill and so the volcanic 

rocks are included in the bedrock unit. Thick sequences 

of faulted middle Miocene mafic to felsic volcanic flows, 

vents, and domes are widely exposed in the White Hills and 

Black Mountains and probably underlie parts of the Detrital 

Valley and Sacramento Valley basins. In contrast, a thinner 

sequence of volcanic flows fills a paleovalley between the 

Cerbat and Hualapai Mountains near Kingman (fig. 3; Beard 

and others, 2011) and underlies the southern part of the 

Hualapai Valley basin.

The depositional history and resulting facies distributions 

of the Miocene sedimentary deposits and overlying basin fill 

are components of the hydrogeologic framework. The middle 

Miocene sedimentary deposits are commonly interlayered 

with volcanic rocks (fig. 4A), typically well consolidated, and 

are faulted and tilted. The volcanic rocks, which are exposed 

in the White Hills and locally in the Black Mountains (figs. 1, 

3) probably underlie at least some parts of the valley basins; 

basin-fill rocks are mostly coarse-grained clastic units formed 

in alluvial fans mostly derived from fault scarps along the 

basin margins. Late Miocene sedimentary deposits include 

fine grained clastic and evaporite units deposited in lacustrine/

playa and fringing shoreline depositional settings (fig. 4B). 

Coarser-grained rocks within the younger sedimentary deposits were deposited in alluvial fans and on alluvial plains along 

the margins of the younger basins.

Unconsolidated Pliocene through Holocene alluvial-fan, 

alluvial-plain, valley-axis wash alluvial, and pediment deposits form a veneer on the basin fill in the subbasins and (or) 

mantle pedimented surfaces, mountain slopes, and cliffs (fig. 

4C). Active and inactive Pleistocene through Holocene playa 

deposits form the floor of Red Lake playa in the Hualapai Valley basin (fig. 5A), and eolian deposits occur locally downwind (southeast) of the playa (fig. 3).

Hualapai Valley Basin

The Hualapai Valley basin is both rimmed by and underlain by mainly crystalline Proterozoic rock (Beard and others, 

2011). Middle Miocene volcanic flows occur in the paleovalley near Kingman and extend eastward in the subsurface 

where they underlie Quaternary alluvial sedimentary deposits. 

The rocks include the Peach Spring Tuff (18.5 Ma; Nielsen 

and others, 1990), a moderately welded ash-flow tuff. The volcanic rocks transmit some water in the fractures and interbeds 

of tuffs but are generally too fine grained to yield substantial 

volumes of water to wells (Gillespie and Bentley, 1971). 

The late Miocene Hualapai Limestone overlies the Proterozoic rocks in a buttress unconformity on the northwestern 

edge of Hualapai Valley basin and is interbedded with locally 

derived sedimentary deposits along the northeast edge of the 

valley basin (figs. 1, 3; Beard and others, 2011). The limestone 

typically yields water with an elevated content of total dissolved solids (Towne and Rowe, 2007).

The deepest part of the Hualapai Valley basin is an 

extensional basin that underlies Red Lake playa, formed by 

large down-to-the west displacement on the southern section 

of the Grand Wash Fault (fig. 3). The basin fill consists of 

both early and late Miocene sedimentary deposits, overlain by 

Pliocene through Holocene primarily unconsolidated surficial 

deposits. The basin fill ranges in thickness from 100 to 4,300 

m in the center of the extensional basin. The upper 600 m in 

the extensional basin includes Pliocene through Holocene 

clay and siltstone, with lesser amounts of gypsum, anhydrite, 
10 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Crystalline basement 

Volcanic

rocks 

Older 

basin fill 

Younger basin fill younger sedimentary rocks (Tsy, Tsb, Tsh)

A

B

C Younger surficial deposits 

Older surficial deposits

Older 

basin fill 

Older 

basin fill 

Volcanic

rocks

Volcanic

rocks

Crystalline basement 

Crystalline basement 

(Modified from Beard and others, 2011)

Younger basin fill

Figure 4. Schematic cross-sections showing extensional-basin evolution, structural and stratigraphic relations between older and 

younger basin fill, volcanic rocks, and older and younger surficial deposits. A, Extension from about 16 to 13 Ma forms half-graben 

basins that include coarse-grained alluvial conglomerate and breccia sheets of intermediate-age sedimentary rocks shed from active 

faults and interlayered with volcanic flows. B, Continued Miocene faulting (13 to ~8 Ma) forms subbasins filled by mostly fine-grained 

basin fill. C, Late Pliocene and Quaternary surficial deposits blanket surface of subbasins within valley basin.
Approach 11

and conglomerate deposited in a playa environment. These 

deposits overlay as much as 2,500 m of middle to late Miocene halite, shale, and minor gypsum/anhydrite sedimentary 

deposits that interfinger laterally in the subsurface with coarsegrained conglomerate derived from the Grand Wash Cliffs 

(Faulds and others, 1997). The halite deposits are most likely 

underlain by volcanic rocks and lower Paleozoic strata, downfaulted into the basin along the Grand Wash Fault (Faulds and 

others, 1997). Truxton Wash, Frees Wash, and Hualapai Wash 

contribute Holocene alluvial deposits (table 1), consisting 

mainly of loose, fine-grained basin fill, including mud, silt, 

sand, and minor gravel (Beard and others, 2011).

Detrital Valley Basin

Tilted and faulted middle Miocene volcanic rocks and 

older sedimentary deposits overlie crystalline bedrock in the 

central and northern Black Mountains and western White 

Hills, and probably occur in the subsurface of the Detrital Valley basin. The Hualapai Limestone is exposed along the north 

side of the White Hills into the east edge of the northern part 

of the valley (fig. 3), but has not been penetrated by wells in 

the subsurface (Beard and others, 2011).

The tilted Miocene rocks in the subsurface of the Detrital Valley basin are overlain by late Miocene sedimentary 

deposits (Beard and others, 2011). The central and northern parts of the valley basin contain evaporite (fig. 5B) and 

fine-grained clastic deposits younger basin fill in the subsurface. Wells in the southern part of the valley basin penetrate 

clastic deposits in the upper 300 to 400 m, but the lithology 

of the deeper part of this area in the valley basin is unknown 

(Beard and others, 2011). Pliocene through Holocene surficial alluvial fan and wash deposits unconformably overlie 

the younger and older basin fill deposits (Beard and others, 

(Photograph by M. Truini) (Photograph by M. Truini)

(Photograph by L.S. Beard)

A

C

B

Figure 5. Photographs show exposed sedimentary deposits of 

active playa deposits in Red Lake playa, Hualapai Valley basin (A), 

interbedded fine-grained basin fill and gypsum evaporite deposits 

in the northern Detrital Valley subbasin (B), and alluvial basin fill 

on Buck Mountain (C), in the southern part of the Sacramento 

Valley basin, Mohave County, northwestern Arizona.
12 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

2011). A subsurface bedrock bench, about 200 to 600 m bls, 

which extends 10 km westward of Dolan Springs (fig. 1), is 

overlain by alluvial-fan deposits.

Sacramento Valley Basin

Crystalline bedrock underlies the Cerbat and Hualapai 

Mountains and is locally exposed at the base of the volcanic 

section in the Black Mountains. Middle Miocene volcanic 

rocks in the Black Mountains range in thickness from several 

hundred meters to as much as 2 to 3 km. The Peach Spring 

Tuff is exposed in the Black Mountains on the west-central 

side of the Sacramento Valley basin and in the paleovalley at 

Kingman, and most likely occurs in the subsurface between 

the two areas (Beard and others, 2011). The east side of Sacramento Valley basin is a pediment formed on shallow bedrock 8 

to 10 km westward from the Hualapai Mountain. Southwest of 

Kingman, the pediment is formed mostly on Proterozoic crystalline rocks but locally overlies volcanic rocks. The volcanic 

and crystalline rocks are exposed in isolated hills surrounded 

by alluvial deposits on the pediment surface (Beard and others, 

2011).

The northern part of the Sacramento Valley basin is 

underlain by north-south elongate fault-controlled extensional 

basins, filled with younger basin fill consisting of alternating fine- and coarse-grained clastic deposits (Beard and 

others, 2011). The Bouse Formation (Metzger and Loeltz, 

1973) occurs in the subsurface along Sacramento Wash near 

Topock. Other sedimentary deposits include fine-grained 

clastic younger basin fill that interfingers laterally with and are 

overlain by the alluvial deposits veneering the pediment surface along the east side and west sides of the valley basin (fig. 

5C) and valley-axial wash deposits along the main washes. 

Unlike in the Hualapai Valley and Detrital Valley basins, no 

Table 2. Generalized grouping of lithology from well logs.

Grouping of lithology from well logs

Simplified lithologic grouping for wells 

used to interpret resisitivity and shown 

in figs. 6–24

Sedimentary deposits—coarse and fine grained—primarily cobbles and boulders, secondarily 

silt and clay

Coarse-grained sedimentary deposits

Sedimentary deposits—coarse and medium grained—primarily cobbles and boulders, secondarily sand and gravel

Sedimentary deposits—coarse-grained—generally cobbles and boulders

Sedimentary deposits—fine and coarse grained—primarily clays and silt, secondarily cobbles 

and boulders

Evaporites—primarily gypsum

Evaporite Evaporites—primarily gypsum and fine-grained sedimentary deposits

Evaporites—halite

Evaporites—undefined

Sedimentary deposits—medium and coarse grained—primarily sand and gravel, secondarily 

cobbles and boulders

Sedimentary deposits—medium-grained—generally sand and gravel Medium-grained sediment

Sedimentary deposits—medium and fine grained—primarily sand and gravel, secondarily clay 

and silt

Sedimentary deposits—fine and medium grained—primarily clay and silt, secondarily sand and 

gravel Fine-grained sediment

Sedimentary deposits—fine-grained—generally silt and clay

Sedimentary deposits—clast size undifferentiated Undifferentiated sediment

Sedimentary deposits—primarily coarse grained, indurated (conglomerate) Indurated sediment

Limestone—sometimes with siltstone, Cenozoic in age Limestone

Undifferentiated rock Rock

Crystalline—granite, gniess, and schist Crystalline rocks

Volcanic—mafic—generally basalts and andesite

Volcanic rocks Volcaniclastic—volcanic conglomerate or breccia

Volcanic—felsic—generally rhyolite and dacite and welded tuff

Volcanic—undifferentiated
Approach 13

known evaporite deposits occur in Sacramento Valley basin. 

The unconsolidated clastic deposits yield groundwater with 

generally low contents of total dissolved solids (Towne and 

others, 2001).

Well-Log Lithologic Data

Well logs provided lithology data for ground truthing 

and spatially extrapolating interpretations of the gravity and 

TEM data. Lithologies interpreted from drilling logs for wells 

that penetrate the sedimentary deposits in the Hualapai Valley, 

Detrital Valley, and Sacramento Valley basins were coded 

and entered into a Microsoft Access database that included 

lithologic data from wells in the USGS Groundwater Systems 

Information (GWSI) database and the ADWR wells database 

(Wells-55). Wells in the GWSI and Wells-55 databases were 

primarily used to verify our interpretation of the resistivity 

profiles and the shallower part of the gravity basin geometry 

model. Because the locations of wells in the ADWR database 

are defined by using the land net 1⁄4, 1⁄4, 1⁄4 and so are generally 

not as accurate as those of wells in the GWSI database, which 

uses Global Positioning System (GPS) locations, ADWR data 

were used only to fill in generalized data gaps. Wells penetrating bedrock (crystalline and volcanic) are mostly located 

along the periphery of the subbasins (fig. 6). The well log 

descriptions were divided into broad categories (table 2). Generally clastic sedimentary deposits were categorized on the 

basis of grain-size, whether unconsolidated or consolidated, 

and where possible, evaporite units were identified separately. 

Bedrock was categorized as either crystalline or volcanic. 

Where the sedimentary deposits or bedrock was uninterpretable, it was classified as undifferentiated basin fill or simply 

as rocks.

The Hualapai Valley basin contains 1,439 wells with 

lithologic data, of which 669 are in the USGS GWSI and 

ADWR base data (fig. 7). The deepest well, which reaches 

795 m bls, is located south of Red Lake playa. A total of 42 

were drilled into volcanic rocks, primarily in the southern 

part of the study area (fig. 1), and 60 wells are into crystalline 

rocks, primarily around the edges of the valley basins (fig. 6). 

Many of the wells drilled into volcanic rocks also penetrated 

the underlying crystalline rocks (fig. 6).

The Detrital Valley basin contains 511 wells with lithologic data, of which 319 are in the USGS GWSI and ADWR 

database (fig. 7). The deepest well reached 610 m bls, and is 

located east of the White Hills near the north end of the valley 

basin. A total of 25 wells were drilled into volcanic rocks and 

15 wells into crystalline rocks. Most of the wells that penetrate the volcanic bedrock also penetrated in the underlying 

crystalline rocks (fig. 6).

The Sacramento Valley basin contains 1,387 wells with 

lithologic data, of which 558 are in the GWSI and ADWR 

database (fig. 7). The deepest well, which penetrates 756 m 

bls, is located near Santa Claus in the northern part of the 

valley basin. A total of 64 were drilled into volcanic rocks, 

primarily along the margins of the valley basin and subbasins, 

and 41 into crystalline rocks. Only a few of the wells drilled 

into the volcanic rocks penetrated the crystalline rocks (fig. 6). 

Basin Geometry Model

Although several previous investigations have constructed basin geometry models for the study area (fig. 1), 

new gravity data and new methods of analysis allowed for 

construction of a new basin geometry model for the Hualapai Valley, Detrital Valley, and Sacramento Valley basins. 

Our model characterizes the basin geometry and thickness 

of overlying sedimentary deposits, helping to constrain the 

boundary between basin fill and bedrock in the hydrogeologic 

framework models and to define the geometry of structurally 

controlled subbasins within the larger valley basins.

Previous Subsurface-Geometry Studies

Bedrock depth and subsurface geometry in the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins have 

been previously investigated in both regional studies and more 

focused local studies. Regional studies include that by Oppenheimer and Sumner (1980), who constructed two-dimensional 

gravity profiles across alluvial basins throughout Arizona and 

then interpolated between profiles to produce a three-dimensional basin geometry map. Their study assumed that the average fill density in a particular basin varies as a function of the 

gravity anomaly; larger anomalies were inferred to correspond 

to thicker basin fill and higher average densities, ranging from 

about 2.04 to 2.42 grams per cubic centimeter (g/cm3). Langenheim and others (2010) investigated gravity and magnetic 

anomalies in the northern Colorado River extensional corridor 

and Lake Mead region. They produced a map of the Cenozoic basin thickness based on a gravity inversion and density 

variations within the basement. Their basin-fill-thickness map, 

as well as magnetic and gravity gradient analysis, provided 

a means for mapping faults in the area covered by later 

Cenozoic deposits. Their study, which defined basement (or 

bedrock) to be pre-Cenozoic, differs from the present study in 

that Tertiary volcanic and sedimentary rocks were categorized 

as basin fill. They used the method of Jachens and Moring 

(1990), modified to include subsurface constraints, and used 

the isostatic gravity anomalies and data as input into the analysis. Gravity data were reduced to isostatic anomalies by using 

a crustal density of 2.67 g/cm3

, a sea-level crustal thickness 

of 25 km and a mantle-crust density contrast of 0.40 g/cm3 to 

remove the long-wavelength gravitational effects of isostatic 

compensation of the crust due to topographic loading.

Local basin geometry studies were previously completed for each of the three valley basins using large numbers 

of gravity data collected by the ADWR (Mason and others, 

2007; Conway and Ivanich, 2008; Ivanich and Conway, 2009). 

The three studies each modeled two-dimensional profiles 

of lithologic units from gravity data that were interpolated 

to construct a single three-dimensional model, assuming a 

density of 2.0 g/cm3

 for unsaturated alluvium, 2.25 g/cm3 for 
14 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Truxton Wash

Detrital Wash

Sacramento Wash

Frees Wash

H U A L A P A I V A L L E Y B A S I N

S A C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

30’

35o

34o30’ BLACK 

MOUNTAINS

BLACK

MOUNTAINS

HUALAPAI

MOUNTAINS

MOHAVE

MOUNTAINS

GRAND

WASH

CLIFFS

County

Hwy 15

Volcanic rocks

0 25 50 KILOMETERS

0 20 40 MILES

Bedrock lithology,

from geologic map

EXPLANATION

Well developed into volcanic and 

crystalline rocks

Crystalline rocks

Well developed into crystalline rocks

Well developed into volcanic rocks

Basin boundaries

§ ̈¦40

£¤93

66

66

Base from U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Figure 6. Mohave County, northwest Arizona, showing 

location of wells into volcanic and crystalline rocks.
Approach 15

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Truxton Wash

Detrital Wash

Sacramento Wash

Frees Wash

H U A L A P A I V A L L E Y B A S I N

S A C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

30’

35o

34o30’ BLACK 

MOUNTAINS

BLACK

MOUNTAINS

HUALAPAI

MOUNTAINS

MOHAVE

MOUNTAINS

GRAND

WASH

CLIFFS

County

Hwy 15

Volcanic rocks

0 25 50 KILOMETERS

0 20 40 MILES

Bedrock lithology,

from geologic map

EXPLANATION

Basin boundary

Arizona Department of Water Resources 

well (from Wells55 database)

USGS Groundwater System Information well

§ ̈¦40 Crystalline rocks

£¤93

66

66

Base From U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Figure 7. Mohave County, northwest Arizona, showing 

location of wells in the Arizona Department of Water 

Resources Water Resources database (well-55) and from 

the U.S. Geological Survey (USGS) Groundwater Information 

Systems database.
16 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

saturated alluvium, and 2.67 g/cm3 for bedrock (crystalline 

rocks). Ivanich and Conway (2009) created a basin geometry map for the Hualapai Valley basin based on 456 gravity 

points. A total of 29 profiles were modeled with either three or 

four layers—a bedrock layer, an unsaturated alluvial layer, a 

saturated alluvial layer, and in some profiles a salt layer with 

a density of 2.1 g/cm3. Mason and others (2007) created a 

basin geometry model for the Detrital Valley basin based on 

310 new gravity stations for a total of 1,716 gravity points; 35 

profiles were modeled throughout the valley basin. Conway 

and Ivanich (2008) constructed a basin geometry model of the 

Sacramento Valley basin based on 316 new gravity stations 

for a total of 1,804 gravity points; 36 profiles were modeled 

throughout the valley basin. The present study differs from 

these three ADWR studies by directly modeling a single, 

continuous, three-dimensional depth-to-bedrock surface rather 

than interpolating between two-dimensional profiles.

Basin Gravity Anomaly 

The first series of steps towards constructing a basin 

geometry model involves compiling gravity data, applying 

several corrections to these gravity data, and then constructing 

the basin gravity anomaly. Gravity data from 10,681 stations, 

consisting of published tide- and drift-corrected gravity readings, station positions, and terrain corrections, were used to 

create a basin gravity anomaly map for this study. The data 

include the ADWR dataset (Mason and others, 2007; Conway 

and Ivanich, 2008; Ivanich and Conway, 2009) and historical data obtained from the Pan-American Center for Earth 

and Environmental Studies dataset (Pan-American Center for 

Earth and Environmental Studies, 2008). Free-air and Bouguer 

corrections were calculated by using standard formulas (Hinze 

and others, 2005). The Bouguer correction, including the 

Bullard spherical cap correction, was calculated by assuming 

an Earth radius of 6,371 km, a crustal density of 2.67 g/cm3, 

and a Newtonian gravitational constant of 6.673 x 10-11 cubic 

meters per kilogram-square second (m3kg-1s-2; LaFehr, 1991). 

Corrected gravity values were spatially interpolated by using 

kriging to create the complete Bouguer anomaly (fig. 8A). Grid 

cells located 7 km or more from the closest gravity station 

were filled in a second step by linear interpolation from the 

nearest kriged cells. Anomaly grids were upward-continued to 

a constant elevation of 2,550 m, above the highest topography 

in the model domain, to facilitate iterative forward modeling.

Although the complete Bouguer anomaly takes into 

account the elevation of a gravity station, the attractive mass of 

the underlying material, and the effect of surrounding terrain, 

an effect remains due to varying crustal thickness, caused by 

isostatic compensation, in which regions of elevated topography are underlain by thickened crust. This effect can be significant in areas of high topographic relief, such as in the transition 

from low-lying sedimentary basins to the Colorado Plateau in 

the study area (fig. 1). The effect of isostatic compensation was 

modeled and removed from the complete Bouguer anomaly 

to create the isostatic anomaly by using the Airyroot routine 

(Simpson and others, 1983), assuming a sea-level crustal thickness of 30 km, a crustal density 2.67 g/cm3

, and a mantle-crust 

density contrast of 0.33 g/cm3. Isostatic anomalies at most of 

the bedrock gravity stations range from -45 to -25 milliGal 

(mGal), indicating that crustal densities in the study area are 

less than the value of 2.67 g/cm3. One likely reason for this difference is the widespread deposition of ash-flow tuffs and other 

Tertiary volcanic rocks in the study area (Beard and others, 

2011), which typically have an average density lower than that 

of other bedrock geologic formations (Langenheim and others, 

2010). The most negative bedrock gravity anomalies occur in 

the Black Mountains on the west side of the Detrital Valley 

and Sacramento Valley basins, and correspond to the extensive 

occurrence of volcanic rocks (fig. 8B).

To compensate for the negative-anomaly effect of lowdensity volcanic rocks, a new gravity-anomaly grid was generated from the isostatic anomaly by gridding values only from 

stations on bedrock (which includes volcanic rocks). This 

bedrock gravity grid (fig. 8C) was then subtracted from the 

residual isostatic anomaly to arrive at the basin anomaly grid 

(fig. 8D), using an iterative process to account for the effect of 

low-density sedimentary material on adjacent bedrock stations 

(Jachens and Moring, 1990).

Construction of the Basin Geometry Model

The basin isostatic anomaly (fig. 8D) is caused by a 

density contrast between higher-density bedrock (crystalline 

and volcanic rocks) and lower-density basin fill (boulder and 

cobble conglomerate, gravel and sand, and halite, anyhydrite, 

gypsum, and evaporite deposits). The magnitude of this anomaly is proportional to the thickness of the basin fill. A basin 

geometry model of the geologic units and their density was 

constructed by using the GMSYS-3D software from Geosoft, 

Inc., to simulate a gravity response due to both the thickness 

and lateral extent of basin fill (fig. 8D). An iterative forwardmodeling process was used to construct the basin geometry 

model by simulating a gravity field that most closely matched 

the measured gravity field in the study area (fig.1).

The basin geometry model for the study area consists of 

three lithologic layers. The upper two layers are represented 

by unsaturated and saturated basin fill, and assigned densities 

of 2.0 and 2.25 g/cm3, respectively, on the basis of local and 

regional borehole density logs (Ivanich and Conway, 2009). 

These upper two layers are separated by a continuous surface 

defined by the potentiometric groundwater surface (Anning 

and others, 2007), which coincides with the saturated/unsaturated basin fill boundary. The bottom represents homogeneous 

bedrock with a density of 2.67 g/cm3. If significant compaction of basin fill occurs at depth, the density contrast between 

basin fill and bedrock would be smaller, and basin thicknesses 

would be underestimated. A constant-density bedrock layer is 

appropriate because bedrock heterogeneities have previously 

been removed as the bedrock anomaly. In areas where bedrock 

isostatic anomalies differ significantly across a valley basin, 

such as in the southern part of the Sacramento Valley basin, 
Approach 17

"

"

"

"

"

"

"

Sacramento Wash

Detrital Wash

Frees Wash

Truxton Wash

Hualapai Wash

UV66

UV95

UV68

£¤93

§ ̈¦40

Topock

Kingman

Chloride

Hackberry

White Hills

Dolan Springs

Golden Valley

CALIFORNIA

Red Lake 

Playa

H U

A L A P A I V A L L E Y B A S I N

S A

C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

NEVADA

ARIZONA

36o

35o30’

35o

34o30’

114o30’ 114o

Colorado River

"

"

"

"

"

"

"

Sacramento Wash

Detrital Wash

Frees Wash

Truxton Wash

Hualapai Wash

UV66

UV95

UV68

£¤93

§ ̈¦40

Topock

Kingman

Chloride

Hackberry

White Hills

Dolan Springs

Golden Valley

CALIFORNIA

Red Lake 

Playa

H U

A L A P A I V A L L E Y B A S I N

S A

C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

NEVADA

ARIZONA

36o

35o30’

35o

34o30’

114o30’ 114o

Colorado River

"

"

"

"

"

"

"

Sacramento Wash

Detrital Wash

Frees Wash

Truxton Wash

Hualapai Wash

UV66

UV95

UV68

£¤93

§ ̈¦40

Topock

Kingman

Chloride

Hackberry

White Hills

Dolan Springs

Golden Valley

CALIFORNIA

Red Lake 

Playa

H U

A L A P A I V A L L E Y B A S I N

S A

C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

NEVADA

ARIZONA

36o

35o30’

35o

34o30’

114o30’ 114o

Colorado River

"

"

"

"

"

"

"

Sacramento Wash

Detrital Wash

Frees Wash

Truxton Wash

Hualapai Wash

UV66

UV95

UV68

£¤93

§ ̈¦40

Topock

Kingman

Chloride

Hackberry

White Hills

Dolan Springs

Golden Valley

CALIFORNIA

Red Lake 

Playa

H U

A L A P A I V A L L E Y B A S I N

S A

C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

NEVADA

ARIZONA

36o

35o30’

35o

34o30’

114o30’ 114o

Colorado River

0 10 20 MILES

0 10 20 KILOMETERS

A B

C D

HIGH: -57 

MILLIGALS

LOW: -165

MILLIGALS

HIGH: 0 

MILLIGALS

LOW: -50

MILLIGALS

HIGH: 0

MILLIGALS

LOW: -50

MILLIGALS

HIGH: 0 

MILLIGALS

LOW: -50

MILLIGALS

-140

-120

-100

-80

-60

-160

-40

-30

-20

-10

-40

-30

-20

-10

-40

-30

-20

-10

Figure 8. Basin gravity anomaly in Mohave County, northwest Arizona. A, Complete Bouger anomaly. B, Isostatic residual anomaly. 

C, Bedrock residual anomaly. D, Basin residual anomaly. Gray circles indicate position of gravity measurements. All grids are upwardcontinued to 2,550 m elevation. Color scale for figures B through D is identical.
18 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

the model is more uncertain because the configuration of 

bedrock units with contrasting densities is hidden beneath the 

basin fill. In other words, uncertainty in the bedrock residual 

(fig. 8C) in areas interpolated between bedrock stations results 

in further uncertainty in the basin residual (fig. 8D). Density 

logs from boreholes drilled into the Red Lake salt body in the 

Hualapai subbasin indicate densities of 2.06 and 2.24 g/cm3

for interbedded salt and shale, respectively (Faulds and others, 

1997), not significantly different from the density of basin fill, 

and so a separate model layer for salt was not needed.

After defining lithologic layers for the basin geometry 

model, the next step was to determine the thickness of the 

unsaturated basin fill, after which the thickness of the saturated 

basin fill could be determined in an iterative process. Lithologic layers must be spatially continuous throughout the study 

area (fig. 1) to construct the model, even if this assumption 

requires that they have zero thickness. Thus, where bedrock 

is exposed at the surface, the upper two layers (saturated 

and unsaturated basin fill) are assigned a zero thickness. The 

interface between these layers—a continuous surface that 

coincides with the land surface where bedrock is exposed, and 

at the water table where basin fill is exposed—was created 

as follows. First, a triangulated irregular network (TIN) was 

created by using the water-table contours of Anning and others 

(2007). The boundary of this TIN is the contact, at the land 

surface elevation, between bedrock and basin fill as delineated 

on the 1:2,500,000-scale U.S. aquifers coverage (National 

Atlas, 2010). A breakline representing the subsurface contact 

of the water table with bedrock was constructed by taking the 

TIN boundary, moving it 58 m towards the basin center, and 

lowering it 100 m in elevation, a value representing an average 

depth to water at basin margins in the study area. This breakline simulates the effect of mountain blocks with 60° bounding 

faults, the approximate angle of many, but not all faults in the 

study area. The TIN was then converted to a 90 m pixel-size 

raster by using a natural-neighbor technique, and filtered by 

using a 10-pixel averaging filter to remove artifacts near the 

basin boundary. The final surface representing the saturated/

unsaturated basin fill interface was constructed by combining 

the newly created raster surface where basin fill is exposed, and 

a digital elevation model (DEM) where bedrock is exposed. 

Subtraction of the saturated/unsaturated basin fill interface 

from the land-surface elevation provides the thickness of the 

unsaturated basin fill.

The iterative modeling process requires that only one surface in the model is varied when attempting to match the modeled gravity field to the measured gravity anomaly. Adequate 

independent constraint of the depth to saturated basin fill from 

well log data allows the boundary between the upper layer 

(unsaturated basin fill) and middle layer (saturated basin fill) 

to be fixed. Therefore, the boundary between the middle layer 

(saturated basin fill) and the bottom layer (bedrock) is adjusted 

during the modeling process. A constraint grid was used so 

that no basins were created in areas of exposed bedrock, 

providing a smooth transition from values of 0 (fully constrained, areas of bedrock) to 1 (unconstrained, areas of basin 

fill) over a distance of about 3.5 km and prevented steep drop 

offs in basin thickness at the basin margins. As a final result, 

the modeling process yielded estimates of the basin geometry 

across the study area (fig. 1), which forms the basin geometry 

model (fig. 9).

An independent check on the quality of the gravityderived basin geometry model can be obtained from drill logs, 

although the distribution and depth of wells is a major limiting 

factor. In areas where well-log data was available, the basin 

geometry model was able to provide a more correct approximation of the bedrock boundary along the basin margins. With 

few exceptions, wells penetrated into bedrock are generally 

shallow and near the basin margins (fig. 10). No deep wells—

1,000 m or more, typical of oil and gas exploration—were 

available for use in this study to validate the basin geometry 

model in the deepest basins, and so these depths should be 

taken as estimates only. The spatial configuration of subbasins, 

however, should be accurate, particularly where the bedrock 

anomaly does not vary widely across a valley basin.

Interpreted Resistivity Profiles

Resistivity values from airborne TEM surveys were 

interpreted to help identify the boundary between basin fill and 

bedrock, to help distinguish thick, fine-grained from coarser 

grained basin fill lithologic units, and to construct lithologic 

profiles for use in the hydrogeologic framework. Specifically, 

interpretation of the resistivity data, with ground-truthing from 

surface geology and well-log lithologic data, helped define the 

aquifer extent and allowed for differentiation of fine-grained 

silt, clay, and gypsum/anhydrite and halite, medium- and 

coarse-grained sand and gravel, and crystalline and volcanic 

rocks.

Airborne TEM surveys were conducted in the study 

area by Fugro Airborne Surveys of Calgary, Alberta, Canada 

using the GEOTEM system, which was selected as the survey 

method because of its greater depth of investigation (300–400 

m bls) in comparison with the helicopter-based systems that 

were available in 2006. The GEOTEM system consists of a 

transmitter on an airplane towing a three-coil receiver. The 

system transmits a periodic 30 Hertz (Hz) electromagnetic 

field as a waveform with a half-sine current pulse of 4.045 

milliseconds (ms). The transmitter is offset from the receiver 

approximately 132 m horizontally and 39 m vertically, which 

theoretically provides better depth resolution than a colocated 

transmitter and receiver. Originally, the data were obtained as 

5 ontime channels and 15 offtime channels. However, examination of the dataset indicated that the transient response with 

better definition of early and midtime data would result in 

improved resistivity models. The original data were therefore 

reprocessed to provide 20 offtime channels distributed to 

increase early and midtime samples at the expense of fewer 

late samples, which were generally of insufficient quality. The 

pulse width was 4.05 ms, and the midtimes of the channels 
Approach 19

0 25 50 KILOMETERS

0 20 40 MILES

 EXPLANATION

Estimated depth to bedrock, 

in meters below land surface

Basin Boundary

Gypsum/anhydrite/halite

Halite/Anhydrite

Mudstone

Dominant lithology of subbasin

Limestone

Sandstone

SGWF

CF

BMF

BuMF

DFF

KF

NGWF

Topock

Kingman

Chloride

Hackberry

White Hills

Golden Valley

Dolan Springs

0–200

200.1–600

600.1–800

800.1–1,000

1,000.1–1,200

1,200.1–1,400

1,400.1–1,600

1,600.1–1,800

1,800.1–2,000

2,000.1–2,200

2,200.1–2,400

2,400.1–2,600

2,600.1–2,800

2,800.1–3,000

3,000.1–3,200

3,200.1–3,600

3,600.1–3,800

3,800.1–4,000

4,000.1–4,300

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Detrital

Sacramento Wash

Frees Wash

Truxton Wash

Wash

HUALAPAI VALLEY BASIN

SACRAMENTO VALLEY BASIN

DETRITAL VALLEY BASIN

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

35°30’

35o

34o30’

SOUTHERN 

GREGG SUBBASIN

(1,400 M)

HUALAPAI

SUBBASIN

(4,300 M)

NORTHERN

SUBBASIN

(600 M)

CENTRAL

SUBBASIN

(700 M)

SOUTHERN

SUBBASIN

(1,500 M)

CHLORIDE

SUBBASIN

(900 M)

GOLDEN VALLEY

SUBBASIN

(1,300 M)

DUTCH FLAT 

SUBBASIN

(2,600 M)

KINGMAN

SUBBASIN

(1,200 M)

Fault

Normal fault—bar and ball on downthrown side; 

Low-angle normal fault—hachures on upper plate;

Dashed where concealed

Geophysically defined fault—

inferred from USGS basin geometry model

Fault inferred from gravity map—

dashed where concealed

Faults

Base From U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Figure 9. Basin geometry model showing subbasins and estimated depths given in meters, m in the Hualapai Valley, Detrital Valley, 

and Sacramento Valley Basins, Mohave County, northwestern Arizona. Mapped faults are shown in black; black hachured lines are 

low-angle detachment faults. Faults inferred from basin geometry model gravity model and transient electromagnetic data shown in red. 

Dashed red lines denote higher degree of uncertainty (BMF, Black Mountain Fault; BuMF, Buck Mountain Fault; CF, Chloride Fault; DDF, 

Dutch Flat Fault; KF, Kingman Fault; NGWF, northern section of the Grand Wash Fault; SGWF, southern section of the Grand Wash Fault). 
20 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

ranged from 4.28 to 14.29 ms from the beginning of the pulse 

(Dickinson and others, 2009).

The airborne TEM surveys included 1,293 km of profiles 

in total length that were flown over the 3 valley basins. The 

Detrital Valley basin, which is elongated southeast to northwest, had 21 flightlines equaling 528 km (fig. 11), 12 of which 

were flown generally parallel to the basin and 5 generally 

perpendicular to the basin. Four GEOTEM flightlines flown 

in the Detrital Valley basin extended into the northern part of 

the Hualapai Valley basin, which had a total of 18 flightlines 

equaling 545 km, with 13 north-south flightlines, four eastwest flightlines, and two southeast-northwest flightlines. GEOTEM lines in the Hualapai Valley basin were flown only north 

of the Kingman subbasin because of cultural interference from 

the electrical signals from homes, septic systems, powerlines, 

roads, and other manmade objects close to Kingman. The Sacramento Valley basin had a total of 19 flightlines equaling 220 

km, with 16 eastwest flightlines down the center of the valley 

basins, and three north-south flightlines flown perpendicular to 

the east-west flightlines (fig. 11).

One-dimensional models of electrical resistivity versus 

depth derived from the airborne GEOTEM data were constructed by Petros Eikon, Inc., of Toronto, Ontario, Canada, 

to map subsurface electrical resistivity (Dickinson and others, 

2009). All 20 channels were used to construct the resistivity 

models. The one-dimensional resistivity models were calibrated in several places on the basis of drill-log control, using 

the EMIGMA software from Petros Eikon, Inc. The onedimensional GEOTEM models, which consist of six horizontal 

layers of uniform electrical resistivity, were imported into the 

Environmental Science Research Institute’s ArcGIS software 

as two-dimensional cross sections, which used surface elevations derived from the DEM in combination with well-log 

lithology, groundwater levels, and surface geology to infer 

subsurface lithology (table 1). The two-dimensional cross 

sections of resistivity values are referred to as “uninterpreted 

resistivity profiles,” and the two-dimensional cross sections of 

inferred lithology to as “interpreted resistivity profiles.” The 

inferred lithology within each interpreted resistivity profile 

was digitized in ArcMap and brought into ArcScene to better 

visualize in three-dimensions the basin geometry model, well 

logs, and surface geology. In some places, interpretation of the 

resistivity data was obscured by two factors: (1) areas where 

modeled GEOTEM profiles showed interference from powerlines, housing communities, roads, and other structures; and 

(or) (2) areas where the deeper resistivity signal was obscured 

through attenuation from the overlying low-resistivity signal.

Interpretation of the resistivity profiles involved delineation of lithologic units based on resistivities, with guidance 

from well log lithology and geologic information. The basin 

0

10

20

30

40

50

60

Number of wells

Difference in bedrock depth, in meters

Model is deeper Well logs are deeper

-450 to -350-350 to -250-250 to -150

-150 to -50

-50 to 50

50 to 150

150 to 250250 to 350350 to 450450 to 550550 to 650650 to 750750 to 850850 to 950

950+

(agreement)

Figure 10. Histogram of difference in bedrock depth between the basin geometry model and well logs. Each point that forms the 

histogram population is calculated by subtracting well-log depth from model depth. Negative values indicate that modeled depths are 

below bedrock surface in well logs. Wells that did not reach bedrock were omitted.
Approach 21

Red Lake

Playa

Colorado

River

Lake

Mohave

Lake 

Mead

Hualapai Wash

Color ado River

Truxton Wash

Detrital Wash

Sacramento Wash

Frees Wash

H U A L A P A I V A L L E Y B A S I N

S A C R A M E N T O V A L L E Y B A S I N

D E T R I T A L V A L L E Y B A S I N

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

35°30’

35o

34o30’

EXPLANATION

Basin boundary

GEOTEM profiles in Hualapai Valley basin 

(number represents line number)

GEOTEM profiles primarily in Detrital Valley 

basin (number represents line number)

GEOTEM profiles in Sacramento Valley basin 

(number represents line number)

0 25 50 KILOMETERS

0 20 40 MILES

Base from U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

D2

D1

D3

D4

D5

D6

D7D8

D9

D10

D11D12

D13

D14

D15

D16

D17D18

D19

D20

S1

S2

S3

S4

S5

S7

S6

S8

S9

S10

S11

S12

S13

S14

S15

S16

S17

S18

H1H2

H3

H4

H5H6H7

H8

H9

H10

H18

H11

H12

H13

H19

H14

H15

H16

H17

H1

D1

S1

D21

S19

Figure 11. Mohave County, northwest Arizona, showing location 

of GEOTEM surveys in the Hualapai Valley, Detrital Valley, and 

Sacramento Valley basins.
22 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

fill in the resistivity profiles represented is relatively shallow 

in consideration of the total depth of the basins, and primarily 

correlates with the Miocene basin fill shown in figure 4B and 

the late Pliocene and Quaternary surficial deposits shown in 

figure 4C. The electrical properties of the subsurface basin 

fill and rocks in the three alluvial basins varied depending on 

sediment size, saturated versus unsaturated basin fill, and bedrock type. The resistivity profiles were interpreted by spatially 

delineating the extent of lithologic units and assigning them 

into one of the following classes: unsaturated coarse-grained 

basin fill, unsaturated medium-grained basin fill, unsaturated 

fine-grained basin fill, saturated coarse-grained basin fill, 

saturated medium-grained basin fill, saturated fine-grained 

basin fill, limestone, crystalline rocks, and volcanic rocks. A 

description of these units, including grain size, resistivity, and 

associated depositional environments, is included in tables 1 

and 3. The interpretation of the resistivity data was consistent 

with generalized ranges for basin fill and various rock types 

(Pool and Coes, 1999).

Although the resistivity profiles were mainly used to infer 

basin fill lithology, some of the profiles flown over bedrock 

also delineate bedrock outcrops. Sections of resistivity profiles 

with higher resistivities, between 100 and 200 ohm-meters 

(Ω•m), occur in the shallow subsurface near the boundary 

between crystalline bedrock and alluvial fan deposits along the 

mountain fronts. In some places interpretation of the resistivity 

profiles suggests that the depth to bedrock may differ from the 

basin geometry model (fig. 12). In other places, the well-log 

lithologic data and basin geometry model were used instead of 

the resistivity profiles to better define the transition from crystalline bedrock to alluvial-fan deposits (fig. 13; table 1). In still 

other areas, subhorizontal layers and (or) successive vertical 

changes in resistivity (generally from 30 to 100 Ω•m) along 

the resistivity profiles were mapped as volcanic material where 

surface geology and structure indicated the possible presence 

of volcanic rocks in the subsurface (fig. 14). Well-log lithologic data were commonly available to verify an interpretation 

of volcanic rocks; however, in areas with few or no wells, the 

layered and (or) successive vertical changes in resistivity were 

interpreted to indicate volcanic rocks, as mostly occurred in 

the Golden Valley subbasin of the Sacramento Valley basin.

In areas where few or no well-log lithologic data were 

available, interpretation of the resistivity profiles was inferred 

from general knowledge of the depositional setting of shallow 

subsurface geologic units, including: 

• Lacustrine/playa: typified by limestone, evaporite, 

halite, and mudstone;

• Shorelines/eolian: consisting of typically fine- to coarsegrained clastic sediment—dry deposits of mudstone, 

siltstone, sandstone, pebbly sandstone, and sandy 

conglomerate; and 

• Alluvial fans and alluvial plains: consisting of typically coarse-grained deposits including sandstone and 

conglomerate (table 1). 

Table 3. Relation between lithology and approximate ranges in resistivity values.

Lithologic unit, 

interpreted from

Resisitivity

Lithology from well logs Lithologic description Approximate resistivity 

values

Rock type Grain size (Ohm-meters)

Unsaturated coarse 

grained basin fill Coarse grained sediments Sand, gravel, boulders medium, coarse >50

Unsaturated medium 

grained baisin fill

Medium grained 

sediments Silt, sand, some gravel medium, coarse 30–50

Unsaturated fine grained 

basin fill

Fine grained sediments/

evaporite

Clay, silt, sand, halite, 

gypsum, anhydrite fine 0.5–20

Saturated coarse grained 

basin fill Coarse grained sediments Sand, gravel, boulders medium, coarse >50

Saturated medium grained 

basin fill

Medium grained 

sediments Silt, Sand, some gravel medium, coarse 30–50

Saturated fine grained 

basin fill

Fine grained sediments/

evaporite

Clay, silt, sand, halite, 

gypsum, anhydrite fine 0.5–20

Undifferentiated 

sediments

Grain size 

undifferentiated Not applicable Not applicable .5–100

Indurated sediments Coarse grained and 

indurated Sand, gravel, boulders Not applicable >100

Crystalline bedrock Crystalline bedrock Crystalline bedrock Not applicable >100

Volcanic bedrock Volcanic bedrock Volcanic bedrock Not applicable 20–100
Approach 23

0 10 20 MILES

0 10 20 KILOMETERS

N

EXPLANATION

LITHOLOGIC UNITS, INTERPRETED 

FROM RESISTIVITY (fig. 12B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill

Saturated fine-grained basin fill

Crystalline rock

Volcanic rock

0 15 KILOMETERS

0 10 MILES

LITHOLOGY, FROM WELL LOGS

Coarse-grained basin fill

Medium-grained basin fill

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained basin fill

Evaporite

Volcanic rocks

Crystalline rocks

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METERS (fig. 12A)

(Scale is approximate)

Basin geometry

model

Vertical exaggeration 5:1

S10

S10

BLACK MOUNTAINS

BLACK MOUNTAINS

CERBAT

MOUNTAINS

CERBAT

MOUNTAINS

Wells

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

Approximate 

area shown 

above

S19

S14

BEDROCK LITHOLOGY, FROM 

GEOLOGIC MAP (figs. 12A, 12B)

A

B

Figure 12. Mohave County, northwest 

Arizona, showing perspective view to the 

northeast in the Golden Valley subbasin, 

Sacramento Valley basin, with example 

of where the basin geometry model did 

not match GEOTEM profiles and welllog lithologic interpretation of boundary 

between volcanic bedrock and basin fill 

(arrows). Profiles are numbered in the 

same order as they are in figure 11. 
24 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, FROM 

GEOLOGIC MAP (figs 13A, 13B)

EXPLANATION

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METER (fig. 13A)

LITHOLOGIC UNITS, INTERPRETED 

FROM RESISTIVTY (fig. 13B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill 

Saturated medium-grained basin fill

Saturated fine-grained basin fill

Limestone

Crystalline rock

Volcanic rock 

Basin geometry

model

(Scale approximate)

Vertical exaggeration 5:1

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

Approximate 

area shown 

above

MILES

KILOMETERS

0 5 10

0 12.5

S8

S8

S4

S19

S4

S19

A

B

CERBAT

MOUNTAINS

CERBAT

MOUNTAINS

BLACK MOUNTAINS

BLACK MOUNTAINS

Figure 13. Mohave County, northwest Arizona, 

showing perspective view to the northeast in 

the Golden Valley subbasin of the Sacramento 

Valley basin, with interpretation of high transient 

electromagnetic resistivity values (>100 Ω•m), 

where crystalline bedrock overlain by unsaturated 

alluvial fans (arrows). Profiles are numbered in the 

same order as in figure 11.
Approach 25

0 10 20 MILES

0 10 20 KILOMETERS

Approximate N

area shown 

above

EXPLANATION

0 15 KILOMETERS

0 10 MILES

LITHOLOGY, FROM WELL LOGS

Coarse-grained basin fill

Medium-grained basin fill

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN OHM-METERS

(Scale approximate)

Vertical exaggeration 5:1

S10

S16

S6

Wells

Basin geometry

model

BLACK MOUNTAINS

CERBAT

MOUNTAINS

GEOTEM survey lines 

with resistivity values

volcanic bedrock

Figure 14. Mohave County, northwest Arizona, showing perspective view to northeast in the Golden Valley subbasin, Sacramento 

Valley basin, with example of the uninterpreted resistivity profile with successive changes in resistivity, well log lithology, and surface 

geology, interpreted as volcanic bedrock in the subsurface (arrows). Profiles are numbered in the same order as in figure 11. 
26 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

Each of the generalized depositional settings for the subbasins defined in the basin geometry model (fig. 9) is briefly 

defined here. Basin fill in the Kingman subbasin most likely 

formed in an alluvial-fan depositional environment; basin fill 

in the Hualapai subbasin is generally characterized by playa/

lacustrine depositional environments; basin fill in the southern Gregg subbasin is generally characterized by lacustrine 

and (or) shoreline depositional environments in the north and 

alluvial fan depositional environments in the south; basin fill 

in the northern Detrital subbasin likely formed in lacustrine/

playa depositional environments; basin fill in the central 

Detrital subbasin appears to transition from lacustrine/playa 

to alluvial-fan depositional environments; basin fill in the 

southern Detrital subbasin is generally characterized by an 

alluvial fan depositional environment; basin fill in the Chloride 

subbasin is generally characterized by an alluvial-fan depositional environment; basin fill in the Golden Valley subbasin 

is generally characterized by alluvial-fan and surficial fluvial 

depositional environments; and basin fill in the Dutch Flat 

subbasin is mostly of unknown origin.

Hydrogeologic Framework 

Analysis of the geologic information, well-log lithologic 

data, basin geometry model, and interpreted resistivity profiles 

indicates significant differences in the hydrogeologic frameworks of the Hualapai Valley, Detrital Valley, and Sacramento 

Valley basins. One similarity, however, is that each valley 

basin comprises three major subbasins. This section describes 

the hydrogeologic frameworks for the three valley basins and 

their subbasins.

Hualapai Valley Basin

The three subbasins identified by basin of the Hualapai Valley basin in the geometry model vary in shape and 

depth (fig. 9). The Kingman subbasin is generally oval with a 

southwest-to-northeast axis; an inferred fault (Kingman Fault, 

fig. 3) based on the basin geometry model parallels the southeastern edge of the subbasin (fig. 9). The Hualapai subbasin is 

a north-south elongate east-tilted half-graben controlled by the 

southern section of the Grand Wash Fault that includes a thick 

deposit of gypsum, anhydrite, and halite. The small southern 

Gregg subbasin lies east of the southern section of the Grand 

Wash fault in the northern part of the Hualapai Valley basin.

Kingman Subbasin

The basin geometry model suggests that the depth of the 

Kingman subbasin is about 1,200 m bls (fig. 9). An abrupt 

cutoff to the pediment and a modeled dropoff in the basin 

geometry model forms the southern edge of the Kingman 

subbasin. Wells drilled in the subbasin are generally located 

around the periphery, are shallow, and penetrate volcanic and 

(or) crystalline rocks (fig. 10). No deep wells have been drilled 

close to the center of the basin (fig. 15). Most of the groundwater appears to move northward from the subbasin along 

the east side of Long Mountain. Water levels from well logs 

indicate that there may be small amounts of groundwater in 

basin fill along the west side of Long Mountain.

Resistivity profiles were flown over the north and east 

edge of the Hualapai Valley basin. Most of the Kingman 

subbasin was omitted because of the potential effects from 

cultural interference. Resistivity profiles with values greater 

than 100 Ω•m indicate the presence of a bedrock high on the 

west and east sides of Long Mountain between the Kingman 

and Hualapai subbasins; depths to bedrock in those areas shallow to about 100 to 200 m bls (fig. 15). Unsaturated coarsegrained basin fill with resistivity values greater than 100 Ω•m 

are described in well logs as overlying the bedrock. North of 

the bedrock high on either side of Long Mountain is saturated 

basin fill in medium- to coarse-grained deposits with resistivities ranging from 30 to 100 Ω•m. South of the bedrock high, 

unsaturated basin fill with resistivities greater than 100 Ω•m 

overlies saturated fine-grained basin fill with resistivities ranging from 2 to 10 Ω•m (fig. 15).

Hualapai Subbasin

The basin geometry model suggests that the depth of 

the Hualapai subbasin (fig. 9) is 4,300 m bls, deeper than in 

the ADWR model (3,500 m bls; Ivanich and Conway, 2009). 

The results of this study are consistent with the estimates by 

Faulds and others (1997) that are based on seismic-reflection 

data, and by Langenheim and others (2010) that are based on 

a gravity analysis that incorporated the seismic constraints. 

This study uses a depth-density relation identical to that of the 

ADWR study but includes an iterative basin-bedrock separation process, which likely caused the discrepancy between 

the USGS and ADWR depths for the subbasin. Groundwater 

movement defined by the water-table surface in the Hualapai 

subbasin indicates a shallow hydraulic gradient in the basin 

fill from south to north toward the southern Gregg subbasin 

(Anning and others, 2007).

Shallow basin fill sediments in the Hualapai subbasin are 

interpreted as playa/shoreline deposits, interfingering laterally 

with alluvial fans and washes. Interpretation of the resistivity 

profiles for this area identifies unsaturated alluvial fan deposits ranging in resistivity from 50 to 100 Ω•m, playa deposits 

ranging in resistivity from 5 to 20 Ω•m, and fluvial-channel 

deposits ranging in resistivity from 30 to 50 Ω•m (fig. 16). 

Truxton and Frees Washes form very low-gradient braided 

plain surfaces that flow northward; Kingman Wash is mostly 

floored with silt and fine sand, whereas Truxton Wash contributes coarser sediment (Beard and others, 2011). Localized 

shallow silt and clay deposits yield resistivity values from 5 to 

20 Ω•m. Intermediate storms create high flows in both Truxton 

and Kingman Washes, which deposit fine sediments ranging in 

resistivity from 0.5 to 20 Ω•m into Red Lake playa.
Hydrogeologic Framework 27

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS

Coarse-grained basin fill

Medium-grained basin fill

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained basin fill

Evaporite

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METERS (fig. 15A)

LITHOLOGIC UNITS, FROM INTERPRETED 

RESISTIVITY (fig. 15B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill

Saturated fine-grained basin fill

Crystalline rocks

Volcanic rocks

Basin geometry

model

Wells

EXPLANATION

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

0 15 KILOMETERS

0 10 MILES

Vertical exaggeration 5:1

(Scale approximate)

H19

MOUNTAIN

LONG 

HUALAPAI

MOUNTAINS

MOUNTAINS

PEACOCK

CERBAT MOUNTAINS

A

H13

H9

H14

H7

H10 H11

H19

MOUNTAIN

LONG 

HUALAPAI

MOUNTAINS

MOUNTAINS

PEACOCK

CERBAT MOUNTAINS

B

H13

H9

H14

H7

H10 H11

Approximate 

area shown 

at left

Figure 15. Mohave County, northwest Arizona, 

showing perspective view to the northeast of 

uninterpreted (A) and interpreted (B) resistivity from 

GEOTEM profiles in northern part of the Kingman 

subbasin of the Hualapai Valley basin. Profiles are 

numbered in the same order as in figure 11.
28 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

EXPLANATION

Volcanic rocks

Crystalline rocks

0 5 10

0 12.5

MILES

KILOMETERS

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

N

CERBAT MOUNTAINS

WHITE HILLS

LONG 

MOUNTAIN

GRAND

WASH

CLIFFS

A

GRAND

WASH

CLIFFS

CERBAT MOUNTAINS

WHITE HILLS

LONG 

MOUNTAIN

B 

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES IN 

OHM-METERS (fig. 16A)

(Scale approximate)

Basin geometry

model

LITHOLOGIC UNITS, FROM INTERPRETED 

RESISTIVITY (fig. 16B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill

Saturated fine-grained basin fill

Crystalline rock 

Volcanic rock

Vertical exaggeration 5:1

H18

H18

H4

H4

H9

H9

H17

H17

H16

H16

H15

H15

LITHOLOGY, FROM WELL LOGS 

(figs. 16A and 16B)

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

Wells

0 10 20 MILES

0 10 20 KILOMETERS

GEOTEM survey lines 

with interpreted 

lithology

GEOTEM survey lines 

with resistivity values

Approximate 

area shown 

at left

Figure 16. Mohave County, northwest Arizona, showing perspective view to 

northwest of uninterpreted (A), and interpreted (B) resistivity from GEOTEM 

profiles in Hualapai subbasin, Hualapai Valley basin. Interpretation of resistivity 

may differ along profiles that are perpendicular to one another, suggesting that 

the basin fill may be interlayered and (or) a factor of resistivity modeling where 

some surface interference may have occurred or lithology attenuated signal. 

Profiles are numbered in the same order as in figure 11. 
Hydrogeologic Framework 29

A thick salt body that underlies the alluvial-fan and 

playa deposits at about 400 to 600 m bls extends to a depth 

of at least 4,300 m bls. The lateral extent of the salt body was 

defined by previous studies (Davis and Conradi, 1981; Faulds 

and others, 1997; Ivanich and Conway, 2009). Generally this 

salt body appears to fill most of the Hualapai subbasin laterally 

and vertically to the west edge of the subbasin along the Cerbat Mountains (Faulds and others, 1997). Well-log lithologic 

data and very low electrical resistivities of about 0.5 to 5 Ω•m 

suggest fine sediment and salty water in the shallow subsurface below Red Lake playa, likely above the salt body.

Southern Gregg Subbasin

The basin geometry model suggests that the southern 

Gregg subbasin is small, narrow, and 1,400 m deep at its deepest point (fig. 9), Langenheim and others (2010) also showed 

a small subbasin on the basis of their analysis. Groundwater 

movement in the basin-fill aquifer is restricted by the narrow 

bedrock borders causing an increase in the hydraulic gradient 

from south to north (Anning and others, 2007). The basin fill 

is dissected at the north end of the subbasin by Hualapai Wash, 

exposing Hualapai Limestone and fine-grained lacustrine 

deposits that interfinger laterally with shoreline and alluvialfan deposits.

Farther south in the subbasin, resistivity profiles and 

well-log lithologic data suggest that saturated limestone with 

resistivities of 10 to 30 Ω•m may overlie medium-grained 

basin fill with resistivities 20 to 40 Ω•m at the north end of the 

subbasin (fig. 17). Southward, well-log lithologic data, with 

water levels and resistivities of more than 100 Ω•m, indicate 

that unsaturated coarse-grained basin fill may overlie mostly 

saturated coarse-grained deposits with minor fine-grained 

basin fill.

Detrital Valley Basin

The basin geometry model shows that the Detrital Valley 

basin is underlain by three subbasins. The northern Detrital 

subbasin is partly dissected by Detrital Wash, and so some 

late Miocene basin fill is exposed near Lake Mead (fig. 5B). 

In contrast, the two other subbasins are buried beneath surficial deposits.

Northern Detrital Subbasin

The basin geometry model estimates the depth of the 

northern Detrital subbasin to be 600 m bls (fig. 9), comparable 

to the estimate by Mason and others (2007) of about 700 m 

bls. Water levels toward the center of the subbasin may be 

lower than 400 m bls. The evaporite unit is generally dry, 

although some artesian water levels may be present; therefore, 

groundwater withdrawals from wells drilled in this area would 

likely have low yield and poor water quality (Mason and others, 2007; Towne and Stephenson, 2003).

Well-log lithologic data indicate low resistivities ranging from 0.5 to 5 Ω•m, in interbedded clays and gypsum/

anhydrite/halite deposits (fig. 18). Mason and others (2007) 

referred to the gypsum/anhydrite/halite deposits within the 

subbasin and extending southward as the “clay unit.” Less 

than 1 m of undifferentiated unconsolidated alluvial material, 

described in several well logs, overlies some of the interbedded clays and gypsum/anhydrite/halite deposits (fig. 5B).

Central Detrital Subbasin

The basin geometry model suggests that the depth of 

the central Detrital subbasin may be only 700 m bls (fig. 9); 

Mason and others (2007) estimated its depth to be 700 to 850 

m bls. The central subbasin is not as well defined by the basin 

geometry model as are the two subbasins to the north and 

south, possibly because of lateral density changes related to 

a large alluvial fan from the east that may be influencing the 

modeled basin shape and depth (Beard and others, 2011).

Well-log lithologic data suggest that low resistivities from 

0.5 to 10 Ω•m represent about 200 to 300 m of gypsum/anhydrite/halite in the northern part of the subbasin. Several wells 

on the northeast side penetrated gypsum and clay, with minor 

consolidated conglomerate, and granite at about 400 m bls. 

The upper 100 to 200 m bls generally consists of a coarser 

sand-and-gravel alluvial-fan deposit with resistivities of 60 to 

200 Ω•m (fig. 19), which is locally thicker and probably part 

of a large alluvial fan that extends westward from the White 

Hills (Beard and others, 2011). The top of the gypsum/anhydrite/halite sequence was likely eroded by stream channels and 

filled with 200 to 400 m of alluvial basin fill near the south 

end of the central Detrital subbasin, north of Dolan Springs. 

Resistivities in the 200- to 400-m-thick sequence of alluvial 

basin fill range from 100 to 200 Ω•m (fig. 19).

Groundwater moves northward on a shallow hydraulic 

gradient several hundred meters below the land surface. The 

water table coincides with a sharp drop in resistivities from 

100–200 Ω•m to 5–40 Ω•m (fig. 20) that can be explained from 

a combination of (1) well-log lithologic data that indicates 

that the upper 350 m bls is medium- to coarse-grained basin 

fill underlain by the gypsum/anhydrite/halite sequence, which 

underlies the alluvial fan deposit at about 350 to 400 m bls; and 

(2) water-quality data (Towne and Stephenson, 2003), which 

show elevated concentrations of sodium, chloride, and sulfate, 

likely from dissolution of the underlying gypsum/anhydrite/

halite sequence.

Southern Detrital Subbasin

The basin geometry model from this study and those 

of others (Mason and others, 2007; Langenheim and others, 

2010) indicate that the southern Detrital subbasin is elongate 

north-south. The basin geometry model estimates the depth of 

the subbasin to be 1,500 m bls (fig. 9), consistent with Mason 

and others’ (2007) estimate of 1,000–1,500 m bls. The model 
30 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

EXPLANATION

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

MILES

KILOMETERS

0 5 10

0 12.5

LITHOLOGY, FROM WELL LOGS

(figs. 17A and B)

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

N

GRAND

WASH

CLIFFS

GRAND

WASH

CLIFFS

WHITE HILLS

WHITE HILLS

A

B 

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, 

IN OHM-METERS (fig. 17A)

(Scale approximate) Basin geometry

model

LITHOLOGIC UNITS, INTERPRETED 

FROM RESISTIVITY (fig. 17B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill 

Saturated fine-grained basin fill 

Crystalline rock 

Volcanic rock 

Limestone

Vertical exaggeration 5:1

H1

H1 H2

H2

H3

H3

Wells

0 10 20 MILES

0 10 20 KILOMETERS

GEOTEM survey lines 

with interpreted 

lithology

GEOTEM survey lines 

with resistivity values

Approximate 

area shown 

above

Figure 17. Mohave County, northwest 

Arizona, showing perspective view to 

the northwest of uninterpreted (A) and 

interpreted (B) resistivity from GEOTEM 

profiles in southern Gregg subbasin, 

Hualapai Valley basin. Profiles are 

numbered in the same order as in figure 11. 
Hydrogeologic Framework 31

0 10 20 MILES

0 10 20 KILOMETERS

N

Approximate 

area shown 

above

0 15 KILOMETERS

0 10 MILES

BLACK MOUNTAINS

WHITE HILLS

BLACK MOUNTAINS

WHITE HILLS

Vertical exaggeration 5:1

D12

D12

D14

D14

D21

D21

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS

(figs. 18A and B)

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, 

IN OHM-METERS (fig. 18A)

0.5–5

5.1–10

10.1–20

20.1–30

30.1–40

40.1–50

50.1–60

60.1–100

100.1–200

200.1–400

400.1–900

A

B 

(Scale approximate)

Basin geometry

model

LITHOLOGIC UNITS, FROM 

INTERPRETED RESISTIVITY (fig. 18B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill 

Saturated medium-grained basin fill 

Saturated fine-grained basin fill

Crystalline rock 

Volcanic rock

Wells

EXPLANATION

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

Figure 18. Mohave County, northwest Arizona, 

showing perspective view to the northeast of 

uninterpreted (A) and interpreted (B) resistivity 

from GEOTEM profiles in northern Detrital 

subbasin of the Detrital Valley basin. Profiles are 

numbered in the same order as in figure 11.
32 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES,

IN OHM-METERS (fig. 19A)

0.5–5

5.1–10

10.1–20

20.1–30

30.1–40

40.1–50

50.1–60

60.1–100

100.1–200

200.1–400

400.1–900

LITHOLOGIC UNITS, INTERPRETED 

FROM RESISTIVITY; (fig. 19B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill 

Saturated medium-grained basin fill 

Saturated fine-grained basin fill 

Crystalline rock 

Volcanic rock 

Basin geometry

model

D4

D4

D10

D10

D9

D9

Vertical exaggeration 5:1

Wells

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

BLACK MOUNTAINS BLACK MOUNTAINS

WHITE HILLS

WHITE HILLS

A

B

MILES

KILOMETERS

0 5 10

0 12.5

(Scale approximate)

D5

D5

EXPLANATION

Approximate 

area shown 

above

Figure 19. Mohave County, northwest Arizona, showing 

perspective view to the northeast of uninterpreted (A) and 

interpreted (B) resistivity from GEOTEM profiles in the central 

subbasin in Detrital Valley basin. Interpretation of the resistivity 

may differ along profiles that are perpendicular to one another, 

suggesting that the basin fill may be interlayered and (or) may be 

a factor of resistivity modeling where some surface interference 

may have occurred, or overlying lithology attenuated the signal. 

Profiles are numbered in the same order as in figure 11.
Hydrogeologic Framework 33

0 10 20 MILES

0 10 20 KILOMETERS

N

TRANSIENT ELECTROMAGNETIC 

RESISTIVITY VALUES, IN 

OHM–METERS

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

Basin geometry

model

BLACK MOUNTAINS

0.5–5

5–10

10–20

20–30

30–40

40–50

50–60

60–100

100–200

200–400

400–900

Water level

EXPLANATION

Approximate 

area shown 

above

Saturated basin fill

Unsaturated basin fill

MILES

KILOMETERS

0 5 10

0 12.5

(Scale approximate)

WHITE HILLS

D8

Vertical exaggeration 5:1

Figure 20. Mohave County, northwest Arizona, perspective view to 

the northwest, showing vertical changes in resistivity with depth from 

unsaturated to saturated basin fill on GEOTEM profile D8, overlain 

on the basin geometry model in the central Detrital subbasin of the 

Detrital Valley basin. Profile is numbered as in figure 11.
34 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

by Langenheim and others (2010), which estimates a depth 

of 3,500 m bls, suggests that the basin is an east-tilted halfgraben controlled by a fault on the east.

Well-log lithologic data support interpreting the resistivities ranging from 50 to 200 Ω•m in the upper 300 to 400 m bls 

as alluvial-fan deposits, including sand and gravel and interlayered fine-grained clay, silt, and sand units as much as about 

100 m thick (fig. 21). However, the absence of wells deeper 

than 400 m bls makes it difficult to interpret the deposits in the 

lower part of the subbasin.

Groundwater elevation indicates a groundwater divide 

within the southern Detrital subbasins (Anning and others, 

2007). Water moves from the groundwater divide both northward into the central Detrital subbasin and southward into the 

Sacramento Valley basin (Anning and others, 2007). The depth 

to water is 200 to 250 m bls, without any sharp distinction 

between unsaturated and saturated basin fill as in the central 

Detrital subbasin. Water-quality data (Towne and Stephenson, 

2003) reveal no elevated concentrations of sodium, chloride, 

or sulfate in the subbasin, suggesting the absence of evaporite 

deposits in the subsurface.

Sacramento Valley Basin

The Sacramento Valley basin comprises three subbasins on the basis of the basin geometry model: the Chloride, 

Golden Valley, and Dutch Flat subbasins (fig. 9). Interpretation of resistivity profiles and well-log lithologic data indicate 

fine- to coarse-grained clastic alluvial-fan deposits underlain 

by volcanic and crystalline bedrock. Unlike the Hualapai Valley and Detrital Valley basins, Sacramento Valley basin has no 

known playa evaporite or salt deposits.

Chloride Subbasin

The basin geometry model estimates that the depth of 

the Chloride subbasin is 900 m bls (fig. 9), consistent with the 

estimate of 975 m bls by Conway and Ivanich (2008). The 

subbasin is narrow, bounded on the west by volcanic bedrock 

and on the east by crystalline bedrock and the Chloride Fault. 

The Sacramento Valley basin is likely an east-tilted halfgraben; however, the basin geometry model also indicates a 

steep margin along the west side of the valley basin. The west 

side may also be fault controlled, suggesting that the Chloride 

subbasin is either a graben or an abrupt variation in rock densities from fine-grained deposits to coarse-grained alluvial-fan 

deposits (Beard and others, 2011).

Interpretation of resistivity profiles in the Chloride subbasin were complicated in several areas by electromagnetic interference from housing developments. Broad interpretation of 

resistivity profiles, water levels, and limited well-log lithologic 

data suggest unsaturated coarse-grained alluvial fan deposits 

with resistivities greater than 100 Ω•m overlie undifferentiated 

mostly fine- to medium-grained deposits with resistivities of 1 

to 30 Ω•m (fig. 22).

Groundwater moves from the southern Detrital subbasin 

southward into the Chloride subbasin (Anning and others, 2007). The groundwater surface indicates a fairly steep 

hydraulic gradient through the narrow bedrock boundaries of 

the Chloride subbasin between the towns of Santa Claus and 

Golden Valley (figs. 1 and 3). The depth to water is 250 to 320 

m bls in wells drilled near the center of the subbasin.

Golden Valley Subbasin

The basin geometry model estimates the depth of the 

Golden Valley subbasin to be 1,300 m bls (fig. 9). Conway 

and Ivanich (2008) estimated its depth at 1,800 m bls and 

Langenheim and others (2010) suggested a depth of as much 

as 3,000 m bls.

Generally unsaturated, coarse-grained basin fill deposits with resistivities greater than 100 Ω•m form the subbasin 

surface. Saturated coarse-grained basin fill with resistivities 

50 to 100 Ω•m overlies fine-grained deposits with resistivities 

1 to 20 Ω•m in the central and southern parts of the subbasin 

(fig. 23). Well-log lithologic data typically describe undifferentiated medium- to coarse-grained basin fill interbedded with 

fine-grained deposits.

The Golden Valley subbasin is most likely floored by 

a west-dipping sequence of volcanic rocks about 0.5 to at 

least 1 km thick; however, only a few well logs suggest the 

presence of volcanic rocks in the subsurface below the water 

table. In the absence of well-log lithologic data, resistivity 

profiles along the east side of the subbasin were interpreted 

to indicate volcanic rocks in areas of subhorizontal layers and 

(or) successive vertical changes in resistivity generally from 

30 to 100 Ω•m.

The groundwater hydraulic gradient is low as the water 

moves from north to south; the depth to water is 140 to 250 m 

bls (Anning and others, 2007). The lateral and vertical extents 

of the saturated basin fill appear to decrease in the southern 

part of the subbasin where volcanic rocks overlie crystalline 

rocks (fig. 23).

Dutch Flat Subbasin 

The basin geometry model estimates the depth of the 

Dutch Flat subbasin to be 2,600 m bls. The subbasin is 

believed to be controlled by the Buck Mountain Fault on the 

southwest and the inferred Dutch Flat Fault on the northeast 

side, suggesting that this subbasin may be a graben or modified half-graben, with the larger-displacement fault on the 

southwest side (figs. 3 and 9; Beard and others, 2011). Little 

is known about the Dutch Flat subbasin and very few subsurface data are available to identify sedimentary types.

Basin fill deposits in the Dutch Flat subbasin are characterized by an alluvial-fan depositional environment. A 

few wells that penetrate only the very top several hundred 

meters below land surface in the subbasin suggest interlayers 

of clays, sands, and gravels. Resistivity profiles were flown 
Hydrogeologic Framework 35

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS 

(figs. 21A and B)

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METERS (fig. 21A)

0.5–5

5.1–10

10.1–20

20.1–30

30.1–40

40.1–50

50.1–60

60.1–100

100.1–200

200.1–400

400.1–900

CERBAT MOUNTAINS

CERBAT MOUNTAINS

A

B

LITHOLOGIC UNITS, FROM 

INTERPRETED RESISTIVITY (fig. 21B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill 

Saturated medium-grained basin fill 

Saturated fine-grained basin fill 

Crystalline rock 

Volcanic rock 

Basin geometry

model

D9

D9

D4

D1

D1

D4

D5

D5

Vertical exaggeration 5:1

Wells

EXPLANATION

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

Approximate 

area shown 

above

0 5 10 20

0 10 20

MILES

KILOMETERS

(Scale approximate)

Figure 21. Mohave County, northwest Arizona, showing 

perspective view to the northeast of uninterpreted (A) 

and interpreted resistivity (B) from GEOTEM profiles in 

the southern Detrital subbasin in Detrital Valley basin. 

Interpretation of resistivity may differ along profiles that 

are perpendicular to one another, suggesting that the basin 

fill may be interlayered and (or) a factor of the resistivity 

modeling where some surface interference may have 

occurred or overlying lithology attenuated signal. Profiles 

are numbered in the same order as in figure 11.
36 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, FROM 

GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS 

(figs. 21A and B)

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

A

B

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM METERS (fig. 22A)

Basin geometry

model

LITHOLOGIC UNITS, FROM 

INTERPRETED RESISTIVITY (fig. 22B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill 

Saturated fine-grained basin fill

Crystalline rock

Volcanic rock

Vertical exaggeration 5:1

Wells

GEOTEM survey lines 

with resistivity values

GEOTEM survey lines 

with interpreted 

lithology

MILES

KILOMETERS

0 5 10

0 12.5

(Scale approximate)

S16

S16

S14

S14

S19

S19

EXPLANATION

Approximate 

area shown 

Figure 22. Mohave County, northwest above

Arizona, showing perspective view to 

the northeast of uninterpreted (A) and 

interpreted (B) resistivity for GEOTEM 

profiles in the Chloride subbasin of the 

Sacramento Valley basin. Profiles are 

numbered in the same order as in figure 11.
Hydrogeologic Framework 37

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METERS (fig. 23A)

A

B

MILES

KILOMETERS

0 5 10

0 12.5

(Scale approximate)

BLACK MOUNTAINS

BLACK MOUNTAINS

HUALAPAI MOUNTAINS

HUALAPAI MOUNTAINS

LITHOLOGIC UNITS, 

FROM INTERPRETED RESISTIVITY (fig. 23B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill 

Saturated fine-grained basin fill 

Crystalline rock 

Volcanic rock

Basin geometry

model

Vertical exaggeration 5:1

Wells

GEOTEM survey lines 

with interpreted 

lithology

GEOTEM survey lines 

with resistivity values

S4

S7

S13

S4

S7

S13

S19

S18

S19

S18

Area where the saturated 

sediment descreases 

EXPLANATION

Approximate 

area shown 

above Figure 23. Mohave County, northwest Arizona, 

showing perspective view to the northeast of 

uninterpreted (A) and interpreted (B) resistivity for 

GEOTEM profiles in Golden Valley subbasin of the 

Sacramento Valley basin. Profiles are numbered 

in the same order as in figure 11.
38 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

only over the northern part of the subbasin. The fine-grained 

basin fill inferred from resistivity profiles overlies the bedrock 

between the northern part of the Dutch Flat subbasin and the 

Golden Valley subbasin. Well-log lithologic data and resistivities of 1 to 30 Ω•m suggest saturated fine- to medium-grained 

deposits overlain by unsaturated fine- to coarse-grained 

indurated deposits (fig. 24) within the limited area covered by 

resistivity profiles.

Groundwater in the Dutch Flat subbasin moves from the 

north and east sides and discharges into the Colorado River 

west of the town of Topock (Anning and others, 2007). The 

hydraulic gradient is shallow in the eastern part of the subbasin and steepens westward through the medium- to coarsegrained basin fill between the mountains.

Groundwater Storage

The hydrogeologic framework and datasets provide an 

understanding of the extent and spatial distribution of dry 

sediment deposits within the basin fill aquifer, and therefore 

were the foundation for estimating the volume of groundwater 

stored in the basin fill aquifers in the Hualapai Valley, Detrital 

Valley, and Sacramento Valley basins. This volume depends 

on the spatial extent of these aquifers and the distribution 

of specific yield within them, where “specific yield” can be 

defined as the portion of water stored in the aquifer pore space 

that can be drained owing to reduced hydraulic head. Specific 

yield depends on the texture and porosity of the basin fill 

aquifer, and so estimates of the volume of stored groundwater 

depend not only on the extent of the basin fill aquifers but also 

on the spatial distribution of sedimentary grain sizes.

The storage estimates presented here are of the volume 

of groundwater that the basin fill aquifers will yield to a depth 

of 400 m bls for the whole valley basin, as well as for specific 

hydrogeologic units (HGUs). These estimates of groundwater 

storage are cautious and do not take into account many other 

factors that limit the volume of water actually available. Alley 

(2007) discussed how aquifer permeability, water quality, and 

the cost of well drilling, are among the factors that limit the 

volume of water actually available in practice.

Construction of the Groundwater Storage Model

We constructed the groundwater-storage model by first 

defining four HGUs within the saturated basin-fill with different sediment characteristics. Using information from the 

hydrogeologic framework, we delineated the spatial extent 

of HGUs within the valley basins so that the volume for each 

HGU could be calculated for each valley basin. Then, using 

an assigned percentage of specific yield for each HGU, we 

determined the volume of groundwater that could be obtained 

from aquifer storage. The boundary of the model was defined 

by using the ADWR groundwater-basin boundaries for the 

Hualapai Valley, Detrital Valley, and Sacramento Valley 

basins, assuming that the aquifers (to 400 m bls) were primarily unconfined within all three valley basins.

The four HGUs defined for estimating groundwater 

storage are distinguishable on the basis of grain-size characteristics and the uncertainty of their spatial extent within each 

valley.

1. Saturated coarse-grained basin fill (SCBF) consists primarily of sand, gravel, and cobble with 

lesser amounts of finer-grained deposits. This HGU 

directly corresponds to the saturated coarse-grained 

basin fill and medium-grained basin fill described in 

the hydrogeologic framework (table 3). The extent 

of this HGU is well known from the hydrogeologic 

framework, as discussed in the previous section.

2. Saturated fine-grained basin fill (SFBF) consists 

primarily of silt and clay, with lesser amounts of 

coarser-grained deposits. This HGU directly corresponds to the saturated fine-grained basin fill 

described in the hydrogeologic framework (table 

3). The extent of this HGU is well known from the 

hydrogeologic framework as discussed in the previous section.

3. Saturated undifferentiated unconsolidated basin fill 

(UUBF) consists of both fine- and coarse-grained 

basin fill. The extent of this HGU is well defined 

from the interpreted resistivity surveys and well 

logs. Sedimentary texture, however, is undifferentiated because of lateral or vertical transitions between 

deposits within a short distance, such as interbedding, or because the hydrogeologic framework, especially the interpreted resistivity profiles or well-log 

lithologic data, is less definitive about grain size.

4. Saturated poorly characterized basin fill (PCBF) 

represents subsurface sedimentary deposits where 

saturated basin fill is believed to occur but both grain 

size and extent are poorly characterized because the 

hydrogeologic framework, especially the interpreted 

resistivity profiles, well-log lithologic data, and 

water-level data, are generally sparse and (or) less 

definitive in these areas.

The spatial delineation of the four HGUs within each valley basin was based on analysis and interpretation of geologic 

information, well-log lithologic data, the basin geometry 

model, interpreted resistivity profiles, water-level data and 

topographic data that were used in constructing the hydrogeologic framework. These data were used in the following ways 

for the groundwater-storage model:

•	 Geologic information—the units on the 1:250,000-

scale geologic map (Beard and others, 2011) are correlated with the lithologic description (tables 1 and 

3), allowing the use of data from the geologic map to 

identify the extent of HGUs on the land surface and 

to infer their distribution in the shallow subsurface.
Groundwater Storage 39

0 10 20 MILES

0 10 20 KILOMETERS

N

Volcanic rocks

Crystalline rocks

BEDROCK LITHOLOGY, 

FROM GEOLOGIC MAP

LITHOLOGY, FROM WELL LOGS

Coarse-grained sediments

Medium-grained sediments

Indurated sediments

Volcanic rocks

Crystalline rocks

Undifferentiated sediments

Fine-grained sediments

Evaporite

1–10

11–20

21–30

31–50

51–100

101–900

TRANSIENT ELECTROMAGNETIC

RESISTIVITY VALUES, IN 

OHM-METERS (fig. 24A)

A

B 

LITHOLOGIC UNITS, 

FROM INTERPRETED RESISTIVITY (fig. 24B)

Unsaturated coarse-grained basin fill

Unsaturated medium-grained basin fill

Unsaturated fine-grained basin fill

Saturated coarse-grained basin fill

Saturated medium-grained basin fill 

Saturated fine-grained basin fill 

Crystalline rock

Volcanic rock

Vertical exaggeration 5:1

S4

Undifferentiated rock

Wells

GEOTEM survey lines 

with interpreted 

lithology

GEOTEM survey lines 

with resistivity values

0 5 10 20

0 10 20

MILES

KILOMETERS

HUALAPAI MOUNTAINS

HUALAPAI MOUNTAINS

BLACK

MOUNTAINS

(Scale approximate)

Basin geometry

model

BLACK 

MOUNTAINS

S4

S1

S1

EXPLANATION

Approximate 

area shown 

at right

Figure 24. Mohave County, northwest Arizona, showing 

perspective view to the northeast of uninterpreted (A) 

and interpreted (B) resistivity from GEOTEM profiles in 

the Dutch Flat subbasin of the Sacramento Valley basin. 

Profiles are numbered in the same order as in figure 11.
40 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

•	 Well-log lithology data—the tops and bottoms of 

vertical intervals were assigned a simplified lithologic attribute on the basis of the lithologic description from the well log, along with altitudes based 

on the elevation of the well at the land surface and 

depth along the well log. The vertical intervals were 

used to approximate sedimentary type and bedrock 

contacts in areas between the interpreted resistivity 

profiles.

•	 Interpreted resistivity profiles—the interpreted resistivity profiles were one of the most important datasets in constructing the groundwater storage model 

because they provided information about basin fill 

textures that were used to estimate the approximate 

extent of the HGUs.

•	 Basin geometry model—the data from the basin 

geometry model included the contact between basin 

fill and the bedrock, and so these data were used to 

define the lower extent of HGUs in some areas.

•	 Water-level data—hydrologic data from the report 

by Anning and others (2007) were used to determine 

the boundary between saturated and unsaturated 

basin fills, and so these data helped define the upper 

extent of the HGUs.

•	 Topographic data—DEMs from the National Elevation Dataset (NED; U.S. Geological Survey, 2011) 

were used to constrain the HGUs to occur between 

the land surface and 400 m bls. Data were downloaded from the USGS Seamless Server in UTM 

projection zone 12, North American Datum 1983.

Spatial-extent delineation and volume estimation for 

the HGUs was completed by using spatial-analysis software. 

ArcGIS was used to integrate the geologic information, welllithologic data, the basin geometry model, and interpreted 

resistivity profiles from several different geodatabases. The 

ArcHydro Groundwater Subsurface Analyst software by Aquaveo was used to create gridded surfaces that connected the 

inferred saturated basin fill between resistivity profiles. Gridded surfaces were constructed to best approximate the upper 

and lower boundaries of an HGU. The upper boundary was 

constructed from the water-table-altitude data, and the lower 

surface from the altitude of the bottom of the inferred deposits. 

Grid cells within each surface were 10,000 square meters (m2) 

(100 m by 100 m) in area and snapped to the surface DEM to 

maintain alignment between each cell within each layer. The 

upper and lower grids for each HGU were clipped to the same 

area common to both grids. For each HGU, the lower grid was 

subtracted from the upper grid to determine the HGU thickness. The volume for each HGU in a basin was determined by 

multiplying the HGU thickness of each cell by the cell area. 

For each valley basin, the HGU volumes of each cell were 

summed for a total HGU volume in the basin. Groundwater 

storage was calculated by converting the volume in cubic 

meters calculated for each HGU to cubic kilometers and multiplying the HGU volumes by selected ratios of specific yield 

expressed as the fraction of drainable volume to total volume. 

Estimates of the storage volumes for each HGU were then 

added together for a valley basin total (table 4).

The specific yields were selected largely on the basis of 

the dominant grain size of basin fill in the HGUs. The heterogeneity of the basin fill in the Hualapai Valley, Detrital 

Valley, and Sacramento Valley basins precludes using available aquifer test data in the study area (fig. 1) because those 

data are few and highly site-specific, and cannot be adequately 

used to interpret storage properties for basin fill elsewhere 

(Garner and Truini, 2011). The SCBF HGU, which provides 

much of the groundwater to wells in the Sacramento Valley 

basin, typically produces potable water (fig. 25; Towne and 

others, 2001; Towne and Stephenson, 2003; and Towne and 

Rowe, 2007). Generally, this HGU is fairly permeable with an 

estimated hydraulic conductivity ranging from 0.23 to 1 m per 

day (Gillespie and Bentley, 1971), and so the SCBF HGU was 

assigned a specific yield of 25 percent.

The SFBF HGU consists of fine-grained alluvial/fluvial 

and playa deposits. In the Hualapai Valley basin, this HGU is 

a combination of older playa and fine-grained shoreline and 

valley-axial wash deposits, about 100 to 200 m thick. The 

HGU in the Hualapai subbasin below Red Lake playa and 

southward towards Long Mountain corresponds to mud and 

evaporitic playa deposits (fig. 25). In the Sacramento Valley 

basin, the SFBF HGU is a semi-impermeable layer, 200 to 

300 m thick, that occurs beneath the SCBF HGU. The origin 

of SFBF HGU in Sacramento Valley basin is unknown but 

may represent playa and fluvial deposits and (or) weathered 

ash-flow tuff. Much of the groundwater, however, is retained 

within the basin fill and so the SFBF HGU was assigned a 

specific yield of 6 percent. 

The UUBF HGU commonly consists of interlayered 

fine- and coarse-grained basin fill (fig. 25). The deposits are 

predominantly coarse grained in the Hualapai Valley and 

Sacramento Valley basins, whereas in the Detrital Valley basin 

they are predominantly fine grained. For the Hualapai Valley and Sacramento Valley basins, the HGU was assigned a 

specific yield of 15 percent; for the Detrital Valley basin, the 

HGU was assigned a specific yield of 8 percent to reflect the 

predominance of the fine-grained deposits. The sedimentary 

deposits within the PCBF HGU in the Detrital Valley basin are 

similar to those in the UUBF HGU in the Hualapai Valley and 

Sacramento Valley basins, and so they are likewise assigned a 

specific yield of 15 percent. 

Groundwater-storage estimates generally have considerable uncertainty that results from propagation of statistical 

errors in the volume and specific yield estimates, and this 

uncertainty should be considered when using such estimates. 

Errors in volume estimates that result from errors in estimates 

of the saturated thickness and lateral extent of an HGU were 

qualitatively determined by using the expert opinion of the 

hydrogeologic-framework analyst regarding the uncertainty in 

these estimates. Errors in specific-yield estimates result from 
Groundwater Storage 41

Colorado

River

Lake

Mohave

Lake 

Mead

Color ado River Saturated poorly characterized basin fill (PCBF)

Basin surface background

Fine-grained basin fill (uncertain storage)

H u a l a p a i V a l l e y B a s i n

S a c r a m e n t o V a l l e y B a s i n

D e t r i t a l V a l l e y B a s i n

ARIZONA

CALIFORNIA

ARIZONA

NEVADA

114o30’ 114o

36o

35°30’

35o

34o30’

Black

Mountains

Black

Mountains

Hualapai

Mountains

Mohave

Mountains

Grand

Wash

Cliffs

Groundwater 

Divide

0 25 50 KILOMETERS

0 20 40 MILES

White Hills

Cerbat Mountains

MODELED BASIN-FILL AND 

HYDROGEOLOGIC UNITS USED FOR STORAGE

Saturated fine-grained basin fill (SFBF)

Saturated undifferentiated unconsolidated basin fill (UUBF)

Saturated coarse-grained basin fill (SCBF)

Saturated coarse-grained basin fill overlapping 

saturated fine grained basin fill (SCBF overlying SFBF)

Groundwater-flow direction

Groundwater level—dashed where approximate, 

in meters above sea level

Basin boundary

390

570

480

630

630

540

450

360

270

150

840

880

820

760

910

820

730

670

580

450

Base from U.S. Geological Survey

digital data, 1:100,000, 1982

Universal Transverse Mercator

Projection, Zone 12

Volcanic rocks

Crystalline rock

LITHOLOGIC UNIT, FROM GEOLOGIC MAP

EXPLANATION

Figure 25. Mohave County, northwest Arizona, 

showing areas of modeled saturated sediments 

delineating hydrogeologic unit areas in the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins. 

Groundwater levels from Anning and others (2007). 

Modeled saturated basin fill extends from water 

table to 400 meters below land surface.
42 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

the spatial variation of specific yield within an HGU and from 

errors in selecting a representative specific yield for the HGU. 

As noted above, specific yields for each HGU were selected 

from the literature, and errors associated with these values 

were qualitatively determined as approximately equal to 25 

percent of the range cited in the literature. The errors in volume 

and specific yield for each HGU were expressed as percentage errors and then combined into the percentage error for the 

HGU groundwater-storage estimate by taking the square root 

of the sum of the squared volume error and squared specificyield error. The error for the estimate of total groundwater 

storage in all the HGUs of a valley basin was estimated as the 

square root of the sum of the squared errors for each HGU 

storage estimate, but in units of volume. An approximate lower 

limit for each storage estimate was determined by taking the 

storage estimate and subtracting 1.96 times the error of the 

storage estimate (in volumetric units); similarly, an approximate upper limit was determined by adding 1.96 times the error 

to the storage estimate. Although standard statistical procedures 

were used to propagate errors and determine the upper and 

lower limits of the storage estimates, the uncertainty of assigning volume and specific-yield errors requires emphasizing 

that the estimates of error in reported storage figures are only 

approximations. The results, however, do provide a reasonable 

and qualitative characterization of the amount of uncertainty 

associated with the storage estimates.

Groundwater Storage Estimates

Estimates of the total groundwater storage in aquifers in 

the Hualapai Valley, Detrital Valley, and Sacramento Valley basins are 14.1, 9.8, and 35.1 km3

, respectively (table 4). 

For the Hualapai Valley and Sacramento Valley basins, the 

approach of determining independent groundwater storage 

estimates for multiple HGUs and then adding them together 

for a total groundwater storage estimate resulted in a lower 

uncertainty in the total estimate relative to the uncertainties in 

the individual estimates. For example, the approximate error 

in the estimated total groundwater storage was 20 percent for 

the Sacramento Valley basin, whereas for individual HGUs the 

error ranged from 21 to 50 percent (table 4).

Estimates of the total groundwater storage in the Hualapai Valley basin include independent calculations for the 

SFBF, UUBF, and PCBF HGUs (fig. 25; table 4). The total 

groundwater storage in basin fill aquifers of the three HGUs in 

this valley basin is estimated to be 14.1 km3

. Accounting for 

the uncertainty in the data, however, this estimate could be as 

low as 6.8 km3 or as high as 21.4 km3 (table 3). Most of the 

estimated total groundwater storage is in the UUBF HGU—

9.3 km3. The SFBF HGU contains a similar volume within the 

valley basin; however, together they hold only about a third as 

much storage (3.3 km3; table 3). Ivanich and Conway (2009) 

estimated a similar total groundwater storage as in this study, 

12.4 km3, for a specific yield of 8 percent.

The Detrital Valley basin is defined by a single UUBF 

HGU. This HGU contains a predominance of fined-grained 

over coarse-grained basin fill and so it was assigned a specific 

yield of 8 percent. Water-level data and interpreted resistivity profiles indicate the basin fill is largely fine grained and 

unsaturated in the northern Detrital subbasin (figs. 18, 25), 

and so the groundwater storage in much of this subbasin was 

considered negligible. The total groundwater storage in basin 

fill aquifers in the Detrital Valley, largely in the central and 

southern subbasins, is estimated to be 9.8 km3

. Accounting for 

the uncertainty in the data, however, this estimate could be as 

low as 0.1 km3 or as high as 19.4 km3 (table 4). Mason and 

others (2007) estimated less total groundwater storage than in 

this study, 4.9 km3, using a specific yield of 8 percent. These 

two estimates differ partly because Mason and others included 

a layer of unsaturated basin fill beneath overlying saturated 

basin fill within the central Detrital subbasin. Therefore, this 

study considers the total volume of saturated basin fill and 

exceeded that reported by Mason and others (2007).

Estimates of groundwater storage in the Sacramento 

Valley basin include independent calculations for the SCBF, 

SFBF, UUBF, and PCBF HGUs (fig. 25; table 4). The total 

groundwater storage in basin fill aquifers of these four HGUs 

is estimated to be 35.1 km3. Accounting for the uncertainty 

in the data, however, this estimate could be as low as 21.7 

km3 or as high as 48.5 km3 (table 4). Although little of the 

total groundwater is stored in the SFBF HGU, the other three 

HGUs hold similar groundwater storage (10–12.6 km3). The 

percentage of total groundwater storage held in the PCBF 

HGU is 36 percent for the Sacramento Valley basin, much 

greater than that for the other two basins. Conway and Ivanich 

(2008) estimated the total groundwater in the Sacramento Valley basin to be about 11.7 km3

 for a specific yield of 8 percent. 

Their estimate is lower than that in this study because they 

used a lower specific yield and a smaller volume of saturated 

basin fill.

Summary

This report describes the use of geologic information, 

well-log lithologic data, a basin geometry model, and interpreted resistivity profiles to construct a hydrogeologic framework and to estimate groundwater storage in the Hualapai 

Valley, Detrital Valley, and Sacramento Valley basins. The 

hydrogeologic framework was constructed to describe how 

the bedrock and basin fill influence the movement and storage of groundwater within each of these three valley basins. 

Information from the hydrogeologic framework was used to 

guide delineation of hydrogeologic units (HGUs), defined 

primarily on the basis of sedimentary lithology. The different 

sedimentary lithologies in the basin fill resulted from different depositional environments—primarily lacustrine/playa, 

shoreline, and alluvial fan. We used the HGUs and associated 

specific yields to estimate the total groundwater storage in 

each valley basin.

The basin geometry model indicates that the Hualapai 

Valley basin is underlain by three subbasins that differ in size 
Summary 43

Table 4. Estimated groundwater storage in basin-fill aquifers to 400 meters below land surface in the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, Arizona.[‘–’ not estimated in analysis; volumes given both in cubic kilometers and acre-feet (in parentheses)]

Estimated volume of 

saturated basin fill 

in km3

(acre-ft)

Estimated 

specific yield, 

in percent

Estimated 

groundwater 

storage in km3

(acre-feet)

Approximate error, in percent Approximate 

lower boundary 

for storage estimate 

in km3

(acre-ft)

Approximate 

upper boundary

 for storage estimate 

in km3

(acre-ft)

Hydrogeologic unit Estimated volume Estimated specific yield Estimated groundwater storage

Hualapai Valley basin

Saturated fine-grained basin fill 

(SFBF)

55

(44.6 million) 6 3.3 (2.7 million) 5 50 50 0.05 (40 thousand) 6.6 (5.3 million)

Saturated undifferentiated basin 

fill (UUBF)

62

(50 million) 15 9.3 (7.5 million) 5 35 35 2.9 (2.3 million) 15.7 (12.7 million)

Saturated poorly characterized 

basin fill (PCBF)

10

(8 million) 15 1.5 (1.2 million) 20 35 40 0.3 (240 thousand) 2.7 (2.2 million)

Total, all basin fill sediments to 

400 m bls

127

(102.9 million)

–

14.1

(11.4 million)

– – 26 6.8 (5.5 million) 21.4 (17.3 million)

Detrital Valley basin

Saturated undifferentiated basin 

fill (UUBF and SFBF)

122

(98.9) 8 9.8 (7.9 million) 5 50 50 0.1 (81 thousand) 19.4 (15 million)

Sacramento Valley basin

Saturated fine-grained basin fill 

(SFBF)

16

(13 million) 6 1.0 (810 thousand) 5 50 50 0.01 (8.1 thousand) 1.9 (1.5 million)

Saturated coarse-grained basin 

fill (SCBF)

40

(32.4 million) 25 10.0 (8.1 million) 5 20 21 6.0 (4.9 million) 14.0 (11 million)

Saturated undifferentiated basin 

fill (UUBF)

77

(62 million) 15 11.6 (9.4 million) 5 35 35 3.5 (2.8 million) 19.6 (15.9 million)

Saturated poorly characterized 

basin fill (PCBF)

84

(68.1 million) 15 12.6 (10 million) 20 35 40 2.6 (2.1 million) 22.6 (18 million)

Total, all basin fill sediments to 

400 m bls

217

(176 million)

–

35.1

(28 million)

– – 20 21.7 (17.6 million) 48.5 (39 million)
44 Hydrogeologic Framework and Estimates of Groundwater Storage in Mohave County, Arizona

and depositional setting: the Kingman, Hualapai, and southern Gregg subbasins. Basin fill in the Kingman subbasin is 

characterized by alluvial-fan deposits. Basin fill sediments 

in the Hualapai subbasin is characterized as alluvial-fan and 

playa deposits overlying evaporite deposits, including as much 

as 1,000 m of halite. Basin fill in the southern Gregg subbasin 

is characterized by alluvial-fan deposits overlying limestone. 

Basin fill in the Hualapai Valley basin consists of consolidated 

sedimentary deposits overlain by primarily unconsolidated 

basin fill. The basin fill is more than 4,000 m thick in the 

deepest part of the valley basin but averages 0 to 100 m in 

thickness elsewhere. The lithologic basin fill units within the 

subbasins were deposited in alluvial-fan, shoreline, and playa 

environments. Total groundwater storage is estimated to be 

14.1 km3.

The basin geometry model indicates that the elongate 

north-south Detrital Valley basin is underlain by three subbasins that appear to be formed by a series of opposing halfgraben faults and in various depositional settings: the northern 

Detrital, central Detrital, and southern Detrital subbasins. 

Basin fill in the two northern subbasins include playa deposits 

consisting of gypsum/anhydrite and halite sequences; whether 

they occur in the southern subbasin is unknown. Basin fill in 

the southern Detrital subbasin generally consists of alluvialfan deposits. Basin fill in the Detrital Valley basin consists of 

sedimentary deposits, overlain by unconsolidated to consolidated basin fill. The surface geology consists of Holocene 

valley-axial wash, alluvial-fan, and playa deposits. Total 

groundwater storage is estimated to be 9.8 km3.

The basin geometry model infers three subbasins in 

the Sacramento Valley basin: the Chloride, Golden Valley, 

and Dutch Flat subbasins. Broad interpretation of resistivity 

profiles and limited well-log lithologic data in the Chloride 

subbasin suggest unsaturated basin fill overlying saturated 

undifferentiated medium-grained to mostly fine-grained basin 

fill. Interpretation of resistivity profiles and well-log lithologic data in the Golden Valley subbasin suggests saturated 

medium- to coarse-grained basin fill in the northern part 

overlying fine-grained basin fill in the southern part. Little is 

known about the Dutch Flat subbasin and few data are available to interpret subsurface lithology. Basin fill in the Sacramento Valley basin consists of unconsolidated and consolidated sedimentary deposits, including fine-grained deposits in 

the southern part of the basin, alluvial-fan deposits veneering 

the pediment along the east side, and axial valley deposits 

along the main washes. The fine-grained deposits interfinger 

laterally with coarser grained alluvial-fan deposits. Unlike in 

the Hualapai Valley and Detrital Valley basins, no apparent 

evaporite deposits occur in the Sacramento Valley basin. Estimated groundwater storage for the whole aquifer is 28.5 km3

.

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Produced in Menlo Park Publishing Service Center, California

Manuscript approved for publication July 11, 2012

Edited by George Havach and Claire Landowski

Layout and design by Vivian T. Nguyen
Basins, Mohave County, Arizona—

Truini, Beard, Kennedy, and Anning—Hydrogeologic Framework and Estimates of Groundwater Storage for the Hualapai Valley, Detrital Valley, and Sacramento Valley 

Scientific Investigations Report 2012–5275