Devils Hole 

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Specter Range

Chicago Valley

Nopah Range

Yucca

Flat

Rainier

Mesa

Frenchman

Flat

Jackass

Flats

Yucca

Mountain

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Pahra nagat Range

Spotted Range

Death Valley

Tikaboo 

Valley

ALKALI FLAT–

FURNACE

CREEK

RANCH

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1863

Prepared in cooperation with the U.S. Department of Energy Office of Environmental 

Management, National Nuclear Security Administration, Nevada Site Office, under Interagency 

Agreement DE-EM0004969

Groundwater Characterization and Effects of Pumping in the 

Death Valley Regional Groundwater Flow System, Nevada 

and California, with Special Reference to Devils Hole
Cover: Map of study area showing Alkali Flat–Furnace Creek Ranch, Ash Meadows, 

Bullfrog Hills, Pahrump to Death Valley South, and Pahute Mesa–Oasis Valley 

groundwater basins; and Nevada National Security Site boundary and internal 

operations area, in the Death Valley regional flow system, Nevada and California. 

Source: U.S. Geological Survey.
Groundwater Characterization and Effects 

of Pumping in the Death Valley Regional 

Groundwater Flow System, Nevada and 

California, with Special Reference to 

Devils Hole

By Keith J. Halford and Tracie R. Jackson

Prepared in cooperation with the U.S. Department of Energy Office of Environmental Management, National Nuclear Security Administration, Nevada Site 

Office, under Interagency Agreement DE-EM0004969

Professional Paper 1863

U.S. Department of the Interior

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

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

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

natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS.

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Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. 

Government.

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

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Halford, K.J., and Jackson, T.R., 2020, Groundwater characterization and effects of pumping in the Death Valley 

regional groundwater flow system, Nevada and California, with special reference to Devils Hole: U.S. Geological Survey Professional Paper 1863, 178 p., https://doi.org/10.3133/pp1863.

Associated data for this publication:

Jackson, T.R., and Halford, K.J., 2020, MODFLOW-2005 model and supplementary data used to characterize groundwater flow and effects of pumping in the Death Valley regional groundwater flow system, Nevada and California, 

with special reference to Devils Hole: U.S. Geological Survey data release, https://doi.org/10.5066/P9HIYVG2.

ISSN 1044-9612 (print)

ISSN 2330-7102 (online)
iii

Contents

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

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

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

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

Previous Investigations........................................................................................................................6

Regional Models—1982–97 .......................................................................................................6

Regional Investigations—1998–2004........................................................................................6

Predevelopment Discharge Investigations ....................................................................6

Hydraulic-Property and Water-Use Investigations.......................................................8

Hydrogeologic Framework................................................................................................8

DFRVS.v1 Model...........................................................................................................................9

DVRFS.v2 Model.........................................................................................................................10

Approach..............................................................................................................................................10

Geology..........................................................................................................................................................12

Interbasin Flow Between Groundwater Basins .....................................................................................17

Predevelopment Groundwater Flow.........................................................................................................17

Discharge Areas .................................................................................................................................19

Ash Meadows.............................................................................................................................21

Furnace Creek Area ..................................................................................................................21

Previous Predevelopment Estimates And Conceptual Models ................................21

DV3 Conceptual Model—Three Hydrologically Distinct Periods.............................25

Discharge from Springs...................................................................................................25

Discharge from Phreatophytes on Alluvial Fan ...........................................................26

Furnace Creek Wash—A Transmissive Feature .........................................................26

Mining-Tourism Period—A Steady-State Condition...................................................28

Pahrump Valley ..........................................................................................................................28

Lower Amargosa Area..............................................................................................................30

Saratoga Spring Area ...............................................................................................................32

Recharge..............................................................................................................................................34

Spatially Distributed Long-Term Rates ..................................................................................35

Precipitation-Runoff .........................................................................................................35

Perched and Semi-Perched Groundwater...................................................................36

 Temporal Variability..................................................................................................................36

Hydraulic Conductivity.......................................................................................................................40

Field Estimates of Transmissivity.............................................................................................41

Transmissivity and Rock Type..................................................................................................44

Transmissivity and Thickness ..................................................................................................44

Hydraulic Conductivity and Depth ..........................................................................................46

Hydrogeologic Framework.......................................................................................................49

Discretization ....................................................................................................................50

Water-Table Surface ...............................................................................................50

Vertical Discretization.............................................................................................50

Faults ................................................................................................................................52
iv

Contents—Continued

Hydrogeologic Units.........................................................................................................52

Revisions from Underground Test Area Projects .......................................................54

Hydraulically Mandated Features..................................................................................58

Groundwater Development........................................................................................................................59

Data Compilation.................................................................................................................................59

Pumping and Return Flow .................................................................................................................61

Areas Affected by Pumping ..............................................................................................................63

Central Amargosa Desert and Pahrump Valley ....................................................................63

Central Amargosa Desert................................................................................................64

Pahrump Valley .................................................................................................................64

Jackass Flats..............................................................................................................................66

Isolated Areas of Groundwater Development ......................................................................70

Ash Meadows and Devils Hole ........................................................................................................70

Stresses Affecting Water Levels in Devils Hole...................................................................70

Devils Hole Water-Level Model...............................................................................................74

Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical

 Models.............................................................................................................................................76

Common Construction of Models.....................................................................................................76

Distributing Hydraulic Properties And Recharge..........................................................................76

Hydraulic Conductivity..............................................................................................................78

Specific Yield and Specific Storage .......................................................................................82

Recharge.....................................................................................................................................82

Stress-Response Models .................................................................................................................84

Common Boundary Conditions ................................................................................................84

Predevelopment—DV3-SS Model ..........................................................................................84

Lateral Flow Across Study Area Boundary ..................................................................84

Water Table and Perched Groundwater Assumptions...............................................84

Boundary Conditions........................................................................................................85

Simulation of Springs .......................................................................................................85

Groundwater Development—DV3-AM-AFFCR and DV3-PDVS Models...........................87

Temporal Discretization...................................................................................................88

Boundary Conditions........................................................................................................88

Well ER-6-1-2 main Multiple-Well Aquifer Test—DV3-ER612 Model................................89

Temporal Discretization...................................................................................................89

Boundary Conditions........................................................................................................91

Calibration............................................................................................................................................91

Measurement Observations ....................................................................................................91

Predevelopment Observations—DV3-SS Model ........................................................94

Water-Level Altitudes in Wells ..............................................................................94

Water-Level Altitudes in Evapotranspiration Areas ..........................................94

Spring-Pool Altitudes ..............................................................................................95

Water-Table Altitude Comparisons to Land Surface .........................................95

Water-Level Differences Between Measurement Sites...................................95

Transmissivity Comparisons...................................................................................95
v

Contents—Continued

Conceptual Preferences of Recharge, Predevelopment Discharge, and 

Groundwater-Basin-Boundary Flows .....................................................95

Groundwater-Development Observations—DV3-AM-AFFCR and DV3-PDVS 

Models ..................................................................................................................98

Water-Level Changes..............................................................................................98

Accounting for Temporal Variability in Recharge ..............................................99

Groundwater Capture from Springs and Evapotranspiration Areas...............99

Well ER-6-1-2 main Multiple-Well Aquifer Test—DV3-ER612 Model.....................102

Regularization Observations..................................................................................................102

Goodness of Fit.........................................................................................................................103

Predevelopment Observations .....................................................................................103

Groundwater-Development Observations .................................................................106

Well ER-6-1-2 main Multiple-Well Aquifer Test ........................................................112

Ash Meadows And Devils Hole....................................................................................120

Hydrologic Features .......................................................................................................124

Water Table Beneath Rainier Mesa ...................................................................124

Boundary Between AFFCR and PMOV Groundwater Basins.........................124

Megachannel .........................................................................................................127

Gravity Fault............................................................................................................129

Well AD-4 Corridor.................................................................................................129

Furnace Creek Wash.............................................................................................129

Water Table Beneath Black Mountains and Greenwater Range ..................132

Continuous Aquifer of Carbonate Rocks and Basin Fill in PDVS 

Groundwater Basin..................................................................................133

Simulated Predevelopment Groundwater Flow....................................................................................133

Recharge and Discharge Areas ....................................................................................................133

Flow from Ash Meadows Groundwater Basin to the Furnace Creek Area ............................137

Basin-Fill Flow Conceptualization.........................................................................................137

Flow Potential Through Well AD-4 Corridor...............................................................140

Flow Potential Through Basin Fill in the Central Amargosa Desert.......................141

Basin-Fill, Carbonate-Rock, and Volcanic-Rock Hydraulic Connections..............141

Geochemically Differentiated Sources of Furnace Creek Area Discharge..........141

Major Ions...............................................................................................................141

Stable Isotopes ......................................................................................................144

Deep-Carbonate Flow Conceptualization............................................................................145

Furnace Creek Fault Zone .............................................................................................145

Hydrochemical Evidence...............................................................................................146

Contradictory Results from Drilling and Numerical Simulation ..............................146

Basin-Fill Flow Path More Probable............................................................................147

Predevelopment Water Budgets....................................................................................................147

Pahute Mesa–Oasis Valley Groundwater Basin ................................................................147

Ash Meadows Groundwater Basin ......................................................................................147

Alkali Flat–Furnace Creek Ranch Groundwater Basin......................................................150

Pahrump to Death Valley South Groundwater Basin.........................................................150
vi

Contents—Continued

Rainier Mesa Groundwater Sub-Basin................................................................................150

Effects of Groundwater Development....................................................................................................150

Extent of Water-Level Declines......................................................................................................151

Sources of Pumped Water .............................................................................................................151

Reductions in Natural Discharges ................................................................................................151

Ash Meadows and Devils Hole ......................................................................................................154

Potential Effects of Future Groundwater Development ......................................................................158

Groundwater-Basin Boundary Uncertainty...........................................................................................160

Evaluation of Advective Flow from Corrective Action Units...............................................................160

Model Limitations.......................................................................................................................................163

Summary......................................................................................................................................................165

Acknowledgments.....................................................................................................................................168

References Cited........................................................................................................................................168

Figures

1. Map of study area showing groundwater basins and hydrographic areas in the

Death Valley regional flow system, Nevada and California...................................................3

2. Map showing areal extent of previous regional groundwater models and the

regional model [Death Valley version 3 (DV3)] used in this study, Nevada and

California ........................................................................................................................................7

3. Graph showing minimum, maximum, geometric mean, and 95-percent

confidence interval of log-hydraulic conductivities in 9 hydrogeologic units in

the Death Valley Regional Flow System version 2 model framework using 377

hydraulic-conductivity estimates, Nevada and California.....................................................9

4. Hydrograph showing measured and simulated water-level changes in Devils

Hole from the Death Valley Regional Flow System versions 1 and 2 (DVRFS.v1

and DVRFS.v2) models, Nevada and California, 1930–2018.................................................11

5. Map showing major geologic structures, in the study area, Nevada and California .....16

6. Map showing groundwater basins and major discharge areas in the study area,

Nevada and California ...............................................................................................................18

7. Map showing springs and evapotranspiration areas in the Ash Meadows

discharge area and vicinity, Nevada.......................................................................................22

8. Conceptual model showing groundwater flow to springs and phreatophyte areas

in the Ash Meadows discharge area, Nevada ......................................................................23

9. Map showing discharge locations and the historical water-collection system in

the Furnace Creek area, California..........................................................................................24

10. Hydrographs showing groundwater-level fluctuations in the Furnace Creek area

from collection galleries in Furnace Creek Wash and water-supply wells,

California, 2008–12......................................................................................................................27

11. Map showing discharge areas in Pahrump and Stewart Valleys, Nevada and

California ......................................................................................................................................29

12. Map showing discharge areas in the Lower Amargosa discharge area and

extent of Pleistocene Lake Tecopa, Nevada and California................................................31
vii

13. Graph showing groundwater discharge to river and estimated

evapotranspiration in the Amargosa River downstream of Borehole Spring,

California, on February 27, 2014, and cumulative annual evapotranspiration..................32

14. Map showing upgradient source and discharge areas for the Saratoga Spring

area, California............................................................................................................................33

15. Graphs showing relation between precipitation rate and conceptual recharge

rate from infiltration and runoff to the study area, and cumulative recharge

resulting from this relation, in the study area, Nevada and California..............................36

16. Map showing conceptual recharge distribution, in the study area, Nevada and

California ......................................................................................................................................37

17. Graphs showing winter precipitation (October–March) and excess winter

precipitation (recharge) using 125-percent threshold, and hypothetical

water-level change under predevelopment (steady-state) conditions, in the

study area, Nevada and California, 1900–2016 ......................................................................39

18. Hydrographs showing measured water levels and water-level models for wells

U-19bk and USFWS DR-1, in the study area, Nevada and California, 1910–2018 ............40

19. Map showing transmissivity estimates from single-well aquifer tests and

specific capacity, in the study area, Nevada and California...............................................42

20. Graph showing volume of water pumped or displaced from single-well aquifer

tests (pumping and slug tests) and specific capacity, in the study area, Nevada

and California ..............................................................................................................................44

21. Graphs showing minimum, maximum, median, and 95-percent confidence

interval of log-transmissivities in four rock-type categories from 271 field

estimates of transmissivity, in the study area, Nevada and California..............................46

22. Graphs showing relation between transmissivity and thickness of carbonate

rocks, volcanic rocks, basin fill, and low-permeability rocks, in the study area,

Nevada and California ...............................................................................................................47

23. Graph showing relation between specific capacity and thickness of basin fill

classified as permeable in the Amargosa Desert, Nevada.................................................48

24. Graphs showing average, depth-dependent hydraulic conductivity in volcanic

and carbonate rocks, in the study area, Nevada and California........................................49

25. Map showing differences in the water-table surface between the Death Valley

version 3 (DV3) and Death Valley Regional Flow System version 2 (DVRFS.v2)

hydrogeologic framework, and areas where the DVRFS.v2 hydrogeologic

framework was modified, in the study area, Nevada and California.................................51

26. Example cross sections through intermediate grid of Death Valley Regional Flow

System version 2 (DVRFS.v2) (Belcher and others, 2017; top cross section), and

Death Valley version 3 (DV3; bottom cross section) hydrogeologic framework

models, Nevada and California ................................................................................................55

27. Map showing extents of hydrogeologic framework models for Frenchman Flat,

Yucca Flat–Climax Mine, Rainier Mesa–Shoshone Mountain, and Pahute Mesa

corrective action units; extent of Frenchman Flat basin in Death Valley Regional

Flow System version 2 model (DVRFS.v2) hydrogeologic framework; and areas

where carbonate rocks at water table in DVRFS.v2 were revised to volcanic

rocks, basin fill, or low-permeability rocks in Death Valley version 3 model (DV3)

hydrogeologic framework based on lithologic well data, Nevada and California...........56

Figures—Continued
viii

28. Maps showing hydrogeologic units in Death Valley Regional Flow System

version 2 model (DVRFS.v2), Death Valley version 3 model (DV3), and Fenelon and 

others (2012), at the water table beneath Yucca Flat, Nevada ...........................................57

29. Map showing pumping wells, areas affected by groundwater development, and

hydraulic barriers, in the study area, Nevada and California .............................................60

30. Graphs showing total annual groundwater withdrawals by water-use type,

return flow, and predevelopment discharge by groundwater basin, in the study

area, Nevada and California, 1910–2010, with withdrawal estimates from 2010

projected through 2018 ..............................................................................................................62

31. Graph showing net groundwater withdrawals and return flow, in the study area,

Nevada and California, 1910–2018 ...........................................................................................64

32. Map showing observation wells affected by groundwater development and

hydraulic barriers, in the study area, Nevada and California .............................................65

33. Hydrographs showing water-level changes in well AD-5 in the central Amargosa

Desert and well ESB1 in Pahrump Valley, Nevada, 1910–2018 ...........................................66

34. Graph showing net pumpage in the Alkali Flat-Furnace Creek Ranch groundwater 

basin, and hydrographs showing measured water levels in wells BGMW-8,

NC-EWDP-Washburn-1X(deep), DVJ-02, and Travertine Point 1, in the

central Amargosa Desert, Nevada and California,1910–2018.............................................67

35. Graph showing net pumpage in the Pahrump to Death Valley South groundwater

basin, and hydrographs showing measured water levels in wells BLM Stewart

Valley Well, Last Chance Well, Jeep Trail, 021N010E04L01S, and Hwy 127

MM21-1, around Pahrump Valley, Nevada and California, 1910–2018 ..............................68

36. Graph showing annual pumping from Jackass Flats , and hydrographs showing

measured water levels in wells JF-2, J-13 WW, and JF-3, in Jackass Flats,

Nevada, 1950–2018 .....................................................................................................................69

37. Map showing hydrogeologic units at the water table, wells, Devils Hole, springs,

pumping wells, and injection well [Devils Hole Well (AM-5)] in the Ash Meadows

discharge area and surrounding areas, Nevada ..................................................................71

38. Graph showing monthly pumping from northern wells, southern wells, and

Spring Meadows 6 well and injection into Devils Hole Well (AM-5) by Cappaert

Enterprises in the Ash Meadows discharge area, Nevada, 1968–82 ................................72

39. Graph showing monthly pumping and injection from the Ash Meadows

discharge area, and hydrographs showing measured water levels in wells Devils

Hole Well (AM-5 ), Point of Rocks North (AM-6), and Spring Meadows 7db2,

during groundwater development by Cappaert Enterprises, Nevada, 1965–2000...........73

40. Graphs showing estimated natural water-level fluctuations, long-term natural trend 

of recharge and steady discharge, measured water levels, water-level model that 

includes all natural and pumping stresses, and pumping effects without natural 

fluctuations in Devils Hole, Nevada, 1900–2018 ....................................................................75

41. Map showing boundary of Death Valley version 3 (DV3) model and areas of finer

discretization, in the study area, Nevada and California.....................................................77

42. Diagram showing process for distributing hydraulic conductivities from pilot

points to U.S. Geological Survey finite-difference model (MODFLOW) layers

through hydrogeologic units in a hydrogeologic framework ..............................................79

43. Map showing conceptual transmissivity distribution in shallow carbonate rocks

and hydraulic-conductivity pilot points for the shallow carbonate rocks, in the

study area, Nevada and California ..........................................................................................80

Figures—Continued
ix

44. Map showing extents of all hydrogeologic units and hydraulic-conductivity pilot

points at the water table, in the study area, Nevada and California..................................81

45. Map showing estimated recharge distribution and recharge pilot points, from the

Death Valley version 3 steady-state model (DV3-SS), in the study area, Nevada

and California ..............................................................................................................................83

46. Map showing locations and types of boundary conditions and measurement

observations used in the Death Valley version 3 steady-state model (DV3-SS), in

the study area, Nevada and California....................................................................................86

47. Map showing observation wells monitored during well ER-6-1-2 main

multiple-well aquifer test, in the study area, Nevada and California.................................90

48. Conceptual diagram showing the model-run process of the Death Valley version

3 model (DV3), which is an integrated stress-response model, in the study area,

Nevada and California ...............................................................................................................92

49. Map showing lateral and vertical water-level difference observations used in the

Death Valley version 3 steady-state model (DV3-SS), in the study area, Nevada

and California ..............................................................................................................................96

50. Map showing transmissivity observations from aquifer tests and specific

capacities, in the study area, Nevada and California...........................................................97

51. Hydrograph showing “raw” water-level measurements, measured water levels,

which are annual averages of measured water-level data during an annual

stress period, and simulated water levels in well ESB1, Nevada, 1910–2020 ................100

52. Hydrographs showing “raw” water-level measurements, measured (average)

water-level changes, and simulated water-level changes in terms of depth to

water level and water-level change, at well Travertine Point 1,

California, 1950–2018................................................................................................................100

53. Map showing estimated transmissivity distribution from integrated Death Valley

version 3 model, extent of megachannel, and wells with measured water levels

noticeably affected by natural fluctuations from recharge, Nevada National

Security Site and vicinity, Nevada.........................................................................................101

54. Graph showing comparison of measured and simulated water-level altitudes

from the calibrated Death Valley Regional Flow System version 2 model

(DVRFS.v2) and Death Valley version 3 steady-state model (DV3-SS), in the study

area, Nevada and California ...................................................................................................104

55. Map showing steady-state water-level altitude residuals in the Death Valley

version 3 steady-state model (DV3-SS), in the study area, Nevada and California ......105

56. Graph showing comparison of simulated and measured transmissivities from the

Death Valley Regional Flow System version 2 model (DVRFS.v2) and Death Valley

version 3 steady-state model (DV3-SS), in the study area, Nevada and California ......107

57. Map showing maximum simulated drawdown and selected observation sites

with hydrographs shown in this report, in the study area, Nevada and California,

2018 .............................................................................................................................................108

58. Hydrographs showing “raw” water-level measurements and simulated and

measured (average) water-level declines in wells AD-5, TG Well, and Inyo-BLM1,

in the central Amargosa Desert, Nevada and California, 1950–2018...............................109

59. Hydrographs showing “raw” water-level measurements and simulated and

measured (average) water-level declines in wells AD-1,

NC-EWDP-Washburn-1X (deep), DVJ-02, and WRPMW-4 that result from

pumping in the central Amargosa Desert, Nevada and California, 1950–2018 ..............110

Figures—Continued
x

60. Hydrographs showing “raw” water-level measurements and simulated and

measured (average) water levels in wells GSA, SD2, and JAW, in Pahrump

Valley, Nevada, 1910–2020 ......................................................................................................111

61. Hydrographs showing “raw” water-level measurements and simulated and

measured (average) water-level changes in wells BLM Stewart Valley Well, Last

Chance Well, Jeep Trail, 021N010E04L01S, 022N007E13L01S, and Hwy 127 MM21-1 that 

result from pumping in Pahrump Valley, in the study area, Nevada

and California, 1910–2020 ........................................................................................................113

62. Hydrographs showing comparison of simulated and measured discharges from

Bennetts and Manse Springs, Pahrump Valley, Nevada, 1910–2018...............................114

63. Hydrographs showing “Raw” water-level measurements and simulated and

measured (average) water-level changes in well WW-4 in CP basin, and USAF

Well 3 in Indian Springs, Nevada, 1950–2018.......................................................................115

64. Map showing estimated specific-yield distribution and pilot points from

integrated Death Valley version 3 model, in the study area, Nevada and California....116

65. Map showing estimated storage-coefficient distribution, which is specific

storage times thickness of model layers 2–6, and pilot points from integrated

Death Valley version 3 model, in the study area, Nevada and California .......................117

66. Hydrographs showing periods when well ER-6-1-2 main pumped; simulated

drawdowns from Death Valley version 3 model simulating Jackson and Halford, 

2020 pumping during the ER-6-1-2 main multiple-well aquifer test (DV3-ER612); and 

measured drawdowns, which were estimated from water-level models

(Jackson and Halford, 2019), in wells ER-3-1-2 (shallow), and ER-7-1,

Nevada, 2004–05 .......................................................................................................................118

67. Hydrographs showing periods when well ER-6-1-2 main pumped; simulated

drawdowns from Death Valley version 3 model simulating Jackson and Halford, 

2020 pumping during the ER-6-1-2 main multiple-well aquifer test (DV3-ER612); and 

measured drawdowns, which were estimated from water-level models (Jackson and 

Halford, 2019), in wells UE-1h, and Tracer Well 3, Nevada, 2004–05................................118

68. Map showing estimated transmissivity distribution from integrated Death Valley

version 3 model (DV3), extent of megachannel, and observation sites during well

ER-6-1-2 main multiple-well aquifer test, in the study area, California and Nevada.....119

69. Graphs showing measured, and DV3-SS- and DVRFS.v2-simulated pool altitudes

and spring discharges, and total measured and simulated spring discharges, in

the Ash Meadows discharge area, Nevada ........................................................................121

70. Hydrographs showing “raw” water-level measurements, measured (average)

water-level changes, and simulated water-level changes in the megachannel, 

including wells Tracer Well 3, North Crystal Well, and Spring Meadows 12, and

Devils Hole, Nevada, 1950–2018.............................................................................................122

71. Graph showing monthly pumping by Cappaert Enterprises; injection into Devils

Hole Well (AM-5); total simulated capture in the Ash Meadows discharge area

from DV3-AM-AFFCR model; and hydrographs showing measured and simulated

(DV3-AM-AFFCR model) discharges from Jack Rabbit, Point of Rocks, and Big

Springs, Nevada, 1968–82 .......................................................................................................123

72. Map showing estimated transmissivity distribution from integrated Death Valley

version 3 model and traces of water-level profiles through major hydrologic

features, in the study area, Nevada and California ............................................................126

Figures—Continued
xi

73. Measured water-level profile and simulated water-level profiles from Death

Valley Regional Flow System version 2 model (DVRFS.v2) and Death Valley

version 3 steady-state model (DV3-SS), and transmissivity profile from the

DV3-SS model, through Rainier Mesa, Nevada...................................................................127

74. Measured and simulated water-level profiles, and transmissivity profiles from the 

Death Valley version 3 steady-state model (DV3-SS), through boundary between 

Pahute Mesa–Oasis Valley and Alkali Flat–Furnace Creek Ranch groundwater

basins, Nevada..........................................................................................................................128

75. Measured and simulated water-level profiles, and transmissivity profiles from

the Death Valley version 3 steady-state model (DV3-SS), through megachannel

from Yucca Flat to the Ash Meadows discharge area, Nevada and California.............130

76. Measured and simulated water-level profiles, and transmissivity profiles from

the Death Valley version 3 steady-state model (DV3-SS), through the well AD-4

corridor, Nevada and California .............................................................................................131

77. Measured and simulated water-level profiles, and transmissivity profile from the

Death Valley version 3 steady-state model (DV3-SS), through the Furnace Creek

area, California..........................................................................................................................132

78. Measured and simulated water-level profiles, and transmissivity profile from the

Death Valley version 3 steady-state model (DV3-SS), through the Black

Mountains and Greenwater Range, California....................................................................134

79. Measured and simulated water-level profiles, and transmissivity profile from the

Death Valley version 3 steady-state model (DV3-SS), from the Spring Mountains

to the Amargosa River, Nevada and California....................................................................135

80. Map showing groundwater-flow paths to selected discharge areas and

contributing recharge areas for discharge areas in Oasis Valley, Ash Meadows,

Furnace Creek, Lower Amargosa, and Pahrump and Stewart Valleys, Nevada

and California ............................................................................................................................136

81. Cross section along a simulated groundwater-flow path from the Spring

Mountains to the Amargosa River, Nevada and California ...............................................138

82. Map showing basin-fill and deep-carbonate flow-path conceptualizations from

the Ash Meadows groundwater basin to discharge areas in Furnace Creek,

Nevada and California .............................................................................................................139

83. Cross section along a simulated groundwater-flow path from the Ash Meadows

groundwater basin to the Furnace Creek area through the well AD-4 corridor,

Nevada and California .............................................................................................................140

84. Map showing water-chemistry sites in the Alkali Flat–Furnace Creek Ranch and

Ash Meadows groundwater basins, Nevada and California ............................................142

85. Piper diagram showing major ion water chemistry for sites in the Alkali

Flat–Furnace Creek Ranch and Ash Meadows groundwater basins, Nevada and

California ....................................................................................................................................143

86. Graph showing stable isotopes for sites in the Alkali Flat–Furnace Creek Ranch

and Ash Meadows groundwater basins, Nevada and California.....................................145

87. Maps showing flow-weighted paths from Furnace Creek discharge area to

contributing recharge areas in the Death Valley Regional Flow System version 2

model (DVRFS.v2) and Death Valley version 3 steady-state model (DV3-SS), in

the study area, Nevada and California..................................................................................148

Figures—Continued
xii

88. Map showing predevelopment water budgets within and between geographic

areas in the study area from the Death Valley version 3 steady-state model

(DV3-SS), Nevada and California ...........................................................................................149

89. Graphs showing total annual groundwater withdrawals by groundwater-storage 

depletion, return flow, and capture of discharge from springs and

evapotranspiration areas by groundwater basins Alkali Flat–Furnace Creek Ranch

and Ash Meadows, Pahute Mesa–Oasis Valley, and Pahrump to Death Valley

South, in the study area, 1910–2018, with withdrawal estimates from 2010

projected to 2018.......................................................................................................................152

90. Hydrographs showing measured and simulated discharges from Travertine and

Texas Springs in the Furnace Creek area, California, 1950–2018 .....................................155

91. Map showing pumping centers analyzed for affecting water levels in Devils

Hole, Nevada and California ...................................................................................................156

92. Graphs showing annual net pumpage by pumping center and water-level

changes in Devils Hole by pumping center, as simulated with the Death Valley

version 3 stress-response model simulating groundwater development in the

Ash Meadows, Alkali Flat–Furnace Creek Ranch, and Pahute Mesa–Oasis Valley

groundwater basins, Nevada and California, 1950–2018 ...................................................157

93. Graphs showing groundwater withdrawals and injections; and measured water

levels, and simulated water levels with and without injections, in Devils Hole

Well (AM-5), Nevada, 1960–2000............................................................................................159

94. Hydrograph showing measured water levels without long-term natural

fluctuations from recharge, and simulated water levels from DV3-AM-AFFCR and

DV3-PRED models, in Devils Hole, Nevada, 1950–2100......................................................159

95. Map showing simulated 165-year advective-flow paths from 296 underground

nuclear tests detonated near or below the water table, in the study area,

Nevada National Security Site, Nevada...............................................................................162

Figures—Continued
xiii

Tables

1. Predevelopment discharge estimates from previous and current investigations

for Alkali Flat–Furnace Creek Ranch, Ash Meadows, and Pahute Mesa–Oasis

Valley groundwater basins, Nevada and California, 1982–2018 ...........................................8

2. Groundwater models developed for Death Valley version 3 model (DV3) project ..........12

3. Major lithology and occurrence descriptions of hydrogeologic units in the study

area, as defined in the Death Valley Regional Flow System version 2

hydrogeologic framework, Nevada and California...............................................................13

4. Predevelopment discharge by discharge area for previous and current regional

flow analyses of the study area, Nevada and California .....................................................20

5. Predevelopment and post-development discharge estimates for all sites in the

Furnace Creek area, California, prior to 1880 to 2018 ...........................................................26

6. Relation between simple-rock types and previously defined hydrogeologic units

in the Death Valley Regional Flow System version 2 model (DVRFS.v2)

hydrogeologic framework, Nevada and California...............................................................45

7. Hydrogeologic units in the Death Valley version 3 model (DV3) hydrogeologic

framework that were defined by rock type, depth, and previously defined

hydrogeologic units from the Death Valley Regional Flow System version 2 model

(DVRFS.v2) project, Nevada and California............................................................................53

8. Fraction of return flow and velocity through unsaturated zone, in the study area,

Nevada and California ...............................................................................................................63

9. Springs explicitly simulated in Death Valley version 3 steady-state model (DV3-SS),

estimated predevelopment spring discharge, and the minimum measured

discharge from springs during groundwater development, in the study area,

Nevada and California ...............................................................................................................87

10. Summary of observations and Death Valley version 3 model (DV3) fit to simulated

comparisons, in the study area, Nevada and California......................................................93

11. Expected and simulated groundwater-flow rate observations, in the study area,

Nevada and California ...............................................................................................................98

12. Summary of major hydrologic features simulated in the integrated Death Valley

version 3 model (DV3), for the study area, Nevada and California...................................125

13. Simulated discharges by discharge area for predevelopment (DV3-SS model),

2018 (DV3-AM-AFFCR or DV3-PDVS model), and projected future conditions in

2100 (DV3-PRED model), in the study area, Nevada and California.................................153

14. Pumping centers; net pumpage volumes, 1969–2018; and effect of pumping

centers on water levels in Devils Hole, in the study area, Nevada and California........155
xiv

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2

) 0.09290 square meter (m2)

square mile (mi2

) 2.590 square kilometer (km2)

acre 4,047 square meter (m2

)

Volume

gallon (gal) 3.785 Liter (L)

acre-foot (acre-ft) 1,233 cubic meter (m3

)

cubic mile (mi3

) 4.168 cubic kilometer (km3)

Flow rate

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3

/yr)

cubic foot per second (ft3

/s) 0.02832 cubic meter per day (m3/d)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Velocity

foot per day (ft/d) 0.3048 meter per day (m/d)

foot per year (ft/yr) 0.3048 meter per year (m/yr)

Radioactivity

picocurie per liter (pCi/L) 0.037 becquerel per liter (Bq/L)

Specific capacity

gallon per minute per foot ([gal/min]/ft) 0.2070 liter per second per meter ([L/s]/m)

Hydraulic gradient

foot per foot (ft/ft) 1 meter per meter (m/m)

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

Transmissivity

foot squared per day (ft2

/d) 0.09290 meter squared per day (m2/d) 

International System of Units to U.S. customary units

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

Flow rate

cubic meter per day (m3

/d) 264.2 gallon per day (gal/d)

kilogram per second (kg/s) 2.205 pound per second (lb/s)

Chemical constituent concentration

mg/L 0.0001335 ounce per U.S. gallon (oz/gal)

Density

gram per cubic centimeter (g/cm3

) 62.4220 pound per cubic foot (lb/ft3)

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

(°C) °C = (°F – 32) / 1.8.
xv

Datums

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD29).

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

Altitude, as used in this report, refers to distance above NGVD29.

Supplemental Information

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

Activities for radioactive constituents in water are given in picocuries per liter (pCi/L).

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

foot of aquifer thickness [(ft3

/d)/ft2]ft. In this report, the mathematically reduced form, foot 

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

Abbreviations

2D-FD two-dimensional finite difference

2D-FE two-dimensional finite element

AFFCR Alkali Flat–Furnace Creek Ranch

CAU corrective action unit

DEM digital elevation model

DVSS1 Death Valley steady-state version 1 model

DVSS2 Death Valley steady-state version 2 model

DVRFS Death Valley regional flow system

DVRFS.v1 Death Valley Regional Flow System version 1 model

DVRFS.v2 Death Valley Regional Flow System version 2 model

DV3 Death Valley version 3 model

DV3-AM-AFFCR Death Valley version 3 stress-response model simulating groundwater 

 development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, and 

 Pahute Mesa–Oasis Valley groundwater basins

DV3-ER612 Death Valley version 3 stress-response model simulating pumping during the 

 well ER-6-1-2 main multiple-well aquifer test

DV3-PDVS Death Valley version 3 stress-response model simulating groundwater 

 development in the Pahrump to Death Valley South groundwater basin

DV3-PRED Death Valley version 3 predictive model

DV3-SS Death Valley version 3 stress-response model simulating steady-state 

 (predevelopment) conditions
xvi

ET evapotranspiration

ETGW groundwater discharge by evapotranspiration

HUF Hydrogeologic-Unit Flow package of MODFLOW

IT IT Corporation

MODFLOW USGS modular, finite-difference, groundwater-flow model

MWAT multiple-well aquifer test

NNSS Nevada National Security Site

PDVS Pahrump to Death Valley South

PEST Parameter ESTimation code

PRISM Precipitation-elevation Regressions on Independent Slopes Model

PMOV Pahute Mesa–Oasis Valley

RMS root-mean-square

r2 coefficient of determination

SDWA Safe Drinking Water Act

UGTA Underground Test Area

USGS U.S. Geological Survey

VSU volcanic-sedimentary unit

Abbreviations—Continued
Abstract 1

Groundwater Characterization and Effects 

of Pumping in the Death Valley Regional 

Groundwater Flow System, Nevada and California, 

with Special Reference to Devils Hole

By Keith J. Halford and Tracie R. Jackson

Abstract

Groundwater flow and development were characterized 

in four groundwater basins of the Death Valley regional 

flow system in Nevada and California with calibrated, 

groundwater-flow models. Natural groundwater discharges 

in the Furnace Creek, Lower Amargosa, and Saratoga 

Spring areas were defined and distributed consistently 

with a revised hydrogeologic framework. This simplified 

hydrogeologic framework was limited to four hydraulically 

unique, hydrogeologic units: (1) basin fill; (2) carbonate 

rocks; (3) volcanic rocks; and (4) low-permeability granitic 

and siliciclastic rocks. Hydrogeologic units and division of 

carbonate and volcanic rocks between shallow and deep were 

supported by results from 271 aquifer tests and specificcapacity estimates. Greater than 90 percent of field-estimated 

transmissivity occurred within 1,600 feet (ft) of the water 

table. Pumping in the study area from 1960 to 2010 averaged 

46,000 acre-feet per year (acre-ft/yr), which is 80 percent of 

the predevelopment discharge. The central Amargosa Desert 

and Pahrump Valley were the two primary pumping centers 

and measurably affected water levels across 900 square miles 

in 2018.

Water levels in Devils Hole were a special focus because 

endangered Devils Hole pupfish (Cyprinodon diabolis) are 

affected by water-level declines. Pumping 42,100 acre-ft by 

Cappaert Enterprises, formerly Spring Meadows, Inc., caused 

a 2.3 ft water-level decline in Devils Hole, which temporarily 

reduced habitat of Devils Hole pupfish by 85 percent in 1972. 

If no pumping occurred, water levels in Devils Hole would 

have risen naturally about 1 ft between 1973 and 2018 from 

temporal variations in recharge. The 2.6-ft range of measured 

water-level changes in Devils Hole was simulated with a 

root-mean-square error of 0.2 ft during the 70-year period of 

record. Simulated water-level declines from pumping totaled 

1.4 ft in 2018, with 25 and 34 percent attributed to pumping 

by Cappaert Enterprises and the central Amargosa Desert, 

respectively. Water levels in Devils Hole will decline at rates 

of 0.1–0.2 ft per decade if pumping from Ash Meadows 

groundwater basin and the central Amargosa Desert 

continue at current rates. Effects of future natural water-level 

fluctuations remain unknown.

Ash Meadows and Alkali Flat–Furnace Creek Ranch 

groundwater basins are hydraulically connected near well 

AD-4, about 5 miles south of the town of Amargosa Valley, 

Nevada. About 40 percent of the discharge from the Furnace 

Creek area is recharged in the Ash Meadows groundwater 

basin. Basin fill in the central Amargosa Desert hydraulically 

connects carbonate rocks east of well AD-4 with saturated 

carbonate rocks in the Funeral Range. About 7 percent of 

the 960,000 acre-ft pumped from Ash Meadows and Alkali 

Flat–Furnace Creek Ranch groundwater basins prior to 2019 

was captured discharge from springs and phreatophytes. 

Greater than 40 percent of the 2,080,000 acre-ft pumped 

from Pahrump Valley between 1910 and 2019 was capture 

that primarily discharged from Bennetts and Manse Springs.

Simulated advective-flow distances and velocities from 

underground nuclear tests are within the range of advective 

transport calculations from tritium data and previous 

radionuclide transport investigations. Boundary conditions 

and flow rates from the regional model in this study are 

plausible for local-scale flow and radionuclide transport 

models. Simulated 165-year groundwater-flow paths do not 

extend into pumping areas and effects of regional pumping 

on advective transport are negligible.
2 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Introduction

Potential radionuclide transport, effects of groundwater 

pumping, and groundwater-basin boundary uncertainty 

are of interest in the Death Valley regional flow system, 

which includes four groundwater basins in Nevada and 

California: (1) Pahute Mesa–Oasis Valley (PMOV); (2) Alkali 

Flat–Furnace Creek Ranch (AFFCR); (3) Ash Meadows; 

and (4) Pahrump to Death Valley South (PDVS). These 

groundwater basins compose the 6,720,000-acre study area 

(fig.1). Radionuclides were introduced into the groundwater 

system by underground nuclear testing beneath the Nevada 

National Security Site (NNSS). Groundwater has been 

pumped primarily for irrigation in Pahrump Valley and the 

central Amargosa Desert (Moreo and Justet, 2008), where 

groundwater withdrawals have considerably lowered water 

levels more than 10 mi from each pumping center. Pumping 

for irrigation in the Ash Meadows discharge area during 

the 1970s directly affected water levels in Devils Hole1

, the 

exclusive habitat of the Devils Hole pupfish, Cyprinodon 

diabolis (Dudley and Larson, 1976). [Discharge in this report 

refers to predevelopment (natural) groundwater discharge 

from springs and evapotranspiration areas, whereas pumping 

discharge is referred to as either groundwater development 

or pumping]. Observed water-level changes in Devils Hole

have raised awareness about potential effects of groundwater 

pumping on other federally protected groundwater-dependent 

ecosystems in the regional flow system. Addressing 

groundwater-basin boundary uncertainty is of interest for 

estimating potential radionuclide transport from Pahute Mesa 

(Fenelon and others, 2016) and for determining hydraulic 

connections between pumping centers and groundwaterdependent ecosystems across groundwater-basin boundaries. 

These problems require regional analysis because considerable 

flow occurs between some groundwater basins (Winograd and 

Thordarson, 1975).

Investigation and long-term monitoring of radionuclides 

from 828 underground nuclear tests beneath the NNSS from 

1951 to 1992 (U.S. Department of Energy, 2015) are the focus 

of the U.S. Department of Energy Underground Test Area 

activity (U.S. Department of Energy, 2010). An objective 

of the long-term activity is to assess potential transport 

downgradient of detonations. Radionuclide movement from 

Frenchman Flat, Yucca Flat–Climax Mine, Rainier Mesa–

Shoshone Mountain, and western and central Pahute Mesa 

corrective action units (CAUs) has been investigated since 

the 1990s. Western and central Pahute Mesa CAUs will be 

referred to as the Pahute Mesa CAU in this report. Regional 

1

 Groundwater sites, including wells and springs, are italicized and hyperlinked to their respective data stored in the U.S. Geological Survey National 

Water Information System database.

analysis of groundwater flow remains necessary for hydrologic 

context around CAUs and to estimate advective movement 

beyond CAUs. Boundary conditions and flow rates from 

regional groundwater models also are used to support localscale CAU models of groundwater flow and radionuclide 

transport (Navarro-Intera, LLC, 2013). Because regional 

groundwater models implicitly estimate advective transport, 

showing advective movement along groundwater-flow paths 

is a relevant way to evaluate the reasonableness of using 

simulated flow rates from a regional model in local-scale 

models.

Substantial groundwater pumping for irrigation occurred 

after 1945 with the introduction of high-capacity, turbine 

pumps (Harrill, 1986; Moreo and others, 2003). Successful 

artesian wells were drilled initially in Pahrump Valley and 

the central Amargosa Desert beginning in 1913 and 1916, 

respectively, but total irrigated acreage was less than 700 acres 

and annual pumping totaled 4,000 acre-ft prior to 1945 (Moreo 

and Justet, 2008). Total irrigated acreage increased more than 

tenfold to almost 10,000 acres and annual pumping from 

Pahrump Valley and the central Amargosa Desert exceeded 

46,000 acre-ft in 1965 (Moreo and others, 2003). Annual 

pumping remains substantial, with 17,200 and 17,600 acre-ft 

pumped from Pahrump Valley and the central Amargosa 

Desert, respectively, in 2010. More than 80 percent of 

pumpage in the central Amargosa Desert supplied irrigation, 

whereas irrigation accounted for less than one-quarter of 

pumpage in Pahrump Valley during 2010 (Elliott and Moreo, 

2018).

Groundwater development in the Ash Meadows 

discharge area and near Devils Hole during the late 1960s 

conflicted with preservation of an endangered species, 

the Devils Hole pupfish. Ash Meadows discharge area 

was developed considerably between 1967 and 1970 by a 

ranching corporation, Spring Meadows, Inc. (Dudley and 

Larson, 1976). Government and private conservationists 

forecasted extinction of the Devils Hole pupfish in response 

to expected water-level declines from pumping by Spring 

Meadows, Inc., which became Cappaert Enterprises after 1972 

(Dudley and Larson, 1976; Williams and others, 1996). These 

concerns established a Desert Pupfish Task Force in 1969 that 

recommended identifying causes of water-level declines in 

Devils Hole. A scientific investigation by the U.S. Geological 

Survey (USGS) correlated pumping from eleven wells in 

the Ash Meadows discharge area with water-level declines 

in Devils Hole (Dudley and Larson, 1976). The established 

correlation was sufficient for the U.S Supreme Court, in the 

1976 court case Cappaert v. United States (426 U.S. 128 

[1976]), to limit pumping of groundwater so that a minimum 

pool elevation is maintained in Devils Hole (Williams and 

others, 1996).
Introduction 3

sac19-4233_fig 01

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Devils Hole 

(Subunit of 

Death Valley

National Park)

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

ASH MEADOWS

NATIONAL

WILDLIFE

REFUGE

DEATH

VALLEY

NATIONAL

PARK

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Tikaboo 

Valley

Emigrant 

Valley

Amargosa Wild and Scen ci R vi er

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

AD-4

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

CALIFORNIA

NEVADA

Las Vegas

Study

area

EXPLANATION

National park or monument

Observation well or site

Groundwater basin 

boundary modified 

from Fenelon and 

others (2016)

Nevada National 

Security Site 

boundary and internal

operations area

Hydrographic area 

boundary from 

Rush (1986)

AD-4

Figure 1. Study area showing groundwater basins and hydrographic areas in the Death Valley regional flow system, 

Nevada and California.
4 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Effects of pumping from areas distant from the Ash 

Meadows discharge area and Devils Hole were considered by 

State and Federal agencies after 1976 (Williams and others, 

1996). This was because aquatic and riparian ecosystems in 

a desert environment depend on discharges from an aquifer 

that can encompass areas considerably larger than the 

local topographic basin. For example, recharge to a dozen 

topographic basins (shown as hydrographic areas in fig. 1) 

within the Ash Meadows groundwater basin covers 2,840,000 

acres and supplies the 18,000 acre-ft/yr of discharge in the 

Ash Meadows discharge area (Winograd and Thordarson, 

1975; Laczniak and others, 1999). Hydraulic connections exist 

between many topographic basins, where groundwater moves 

beneath topographic (surface-water) divides. These hydraulic 

connections increase the potential for pumping in a local 

topographic basin to affect discharges in other topographic 

basins.

Hydraulic connections have been recognized between 

two major pumping centers, the central Amargosa Desert and 

Pahrump Valley, and three federally protected groundwaterdependent ecosystems in the study area. The central Amargosa 

Desert is connected hydraulically to the Furnace Creek area 

in Death Valley National Park (Winograd and Thordarson, 

1975, p. C112), and to the Ash Meadows National Wildlife 

Refuge (Claassen, 1985, p. F19; Fenelon and others, 2016, 

p. 6), which is near Devils Hole—a detached unit of Death 

Valley National Park. The Ash Meadows National Wildlife 

Refuge and Devils Hole are part of the Ash Meadows 

discharge area. Pahrump Valley is hydraulically connected 

to a 26-mi perennial reach of the Amargosa River between 

Shoshone, California, and Dumont Dunes (Malmberg, 1967; 

Harrill, 1986), which has been designated as a National 

Wild and Scenic River (Interagency Wild and Scenic Rivers 

Coordinating Council, 2018). Hydraulic properties that define 

degrees of connection and susceptibility to pumping effects 

have not been quantified plausibly, despite recognition of these 

hydraulic connections more than 40 years ago.

The location of one or more boundaries between the 

PMOV, AFFCR, Ash Meadows, and PDVS groundwater 

basins is uncertain. Some of these boundaries are defined by 

water-level altitudes in wells, where water-level declines from 

nearby pumping can affect the location of the boundary and 

degrees of connection between pumping centers and natural 

discharge areas. The southeastern boundary of the PMOV 

groundwater basin between Rainier Mesa and Bare Mountain 

is uncertain based on water-level data (fig. 1; Fenelon and 

others, 2016), and the boundary is susceptible to movement 

by nearby pumping. Addressing boundary uncertainty 

for the PMOV groundwater basin will determine whether 

radionuclides migrating downgradient from Pahute Mesa 

will move only downgradient toward Oasis Valley or, if the 

boundary is affected by pumping, radionuclides potentially 

will migrate southward into the Amargosa Desert.

Characterization of predevelopment flow, advective 

movement, pumping effects, hydraulic connections, and basinboundary uncertainty are best investigated with groundwater 

models of the study area because complex geometries, 

heterogeneous hydraulic properties, and groundwater 

discharges from springs and evapotranspiration areas can be 

simulated consistently. These study objectives are addressable 

with a steady-state model of predevelopment conditions and 

transient models of pumping in the groundwater basins. A 

steady-state model can be used to estimate predevelopment 

water levels, groundwater-flow paths, recharge, spring 

discharges, and groundwater evapotranspiration within each 

groundwater basin. A steady-state model also can be used to 

consistently estimate water budgets between groundwater 

basins. Timing and magnitude of groundwater capture from 

springs and evapotranspiration areas by pumping, in addition 

to water-level changes from pumping, can be estimated 

consistently within each groundwater basin and between 

groundwater basins with a transient model. Steady-state and 

transient models should be developed simultaneously because 

they share common hydraulic properties and related boundary 

conditions in discharge areas.

Development of plausible groundwater models requires 

conceptualizations of predevelopment discharge and recharge 

that are consistent with geologic and hydrologic evidence. 

Groundwater conceptualizations have evolved as new data 

have been collected. Predevelopment discharge estimates 

should be evaluated for consistency with conceptualizations 

of groundwater movement through discharge areas based on 

the relation of discharge estimates to hydrogeologic data, 

water levels, transmissivity estimates, and locations of known 

discharge. Conceptual models of recharge, transmissivity, 

specific-yield, and specific-storage distributions should be 

developed that are consistent with data and observations. For 

example, recharge should be greater in permeable mountain 

ranges than on valley floors because available precipitation is 

greater in mountain ranges. Hydrogeologic framework models 

should be evaluated to determine whether hydrogeologic units 

have unique hydraulic variability and if major hydrologic 

features are incorporated. Testing of the hydrogeologic 

framework requires comparison of hydrogeologic units to 

transmissivity estimates from aquifer tests and specificcapacity estimates.

Plausible results from groundwater models depend 

on model calibration to data and conceptual frameworks. 

Definitive measurements such as water levels, water-level 

changes, predevelopment discharges, and spring capture must 

be replicated at a minimum. Simulated transmissivities must 

compare favorably with aquifer-test results, even if supporting 

volumes of aquifer investigated by pumping are defined 

subjectively, because replicating observed heterogeneity 

depends greatly on transmissivity estimates (Halford, 2016). 

Distributions of recharge, transmissivity, specific yield, and 

specific storage in numerical models also must agree with 

conceptual models of these hydraulic properties. Critical 

hydraulic features and responses must be replicated, such as 

water-level gradients in Yucca Flat and water-level changes in 

Devils Hole.
Introduction 5

Purpose and Scope

The purposes of this report are to:

1. Characterize predevelopment groundwater flow;

2. Evaluate effects of historical (1913–2018) groundwater 

development on water levels and spring discharges;

3. Estimate potential future (2019–2100) effects of 

groundwater development on water levels and spring 

discharges;

4. Evaluate advective flow from selected underground 

nuclear tests to determine if boundary conditions and 

flow rates from the regional model in this study are 

reasonable for local-scale flow and transport models; and

5. Address groundwater-basin boundary uncertainty in the 

study area, which comprises the Ash Meadows, AFFCR, 

PMOV, and PDVS groundwater basins.

Predevelopment groundwater flow, effects of 

groundwater development, advective movement from nuclear 

tests, and basin-boundary uncertainty were investigated with 

three-dimensional, groundwater models. Recharge, hydraulicconductivity, specific-yield, and specific-storage distributions 

were estimated by simultaneously calibrating a steady-state 

model of the study area to predevelopment conditions and 

transient models of groundwater development to waterlevel changes from pumping during 1913–2018. Hydraulicconductivity and specific-yield estimates were constrained 

from specific-capacity tests, aquifer-test results, and analysis 

of multiple-year water-level declines in the central Amargosa 

Desert, Ash Meadows discharge area, Beatty, Bullfrog Hills 

area, Emigrant Valley, Indian Springs, NNSS, Pahrump Valley, 

and Yucca Mountain. A total of four groundwater models, 

which are discussed in more detail in section, “Approach,” 

contributed information to calibrated distributions of hydraulic 

conductivity, specific yield, and specific storage. Potential 

future effects of groundwater development on water levels 

and spring discharges were simulated with a predictive 

groundwater model that used the calibrated distributions of 

hydraulic conductivity, specific yield, and specific storage. 

This predictive model simulated capture of discharge from 

springs and evapotranspiration areas by pumping, where total 

capture was limited to predevelopment discharge rates. All 

pertinent data, analyses, the hydrogeologic framework, and the 

calibrated and predictive groundwater models are published in 

a separate data release (Jackson and Halford, 2020).

Conceptual models of predevelopment and groundwater 

development were required to accomplish the five purposes of 

this study. Characterization of predevelopment groundwater 

flow required conceptual models for recharge, discharge, and 

hydraulic-conductivity distributions within hydrogeologic 

units. Conceptual models integrated water-level data, 

transmissivity estimates, geologic data, water availability in 

recharge areas, and locations and estimates of predevelopment 

discharge. A hydrogeologic framework was used to distribute 

hydraulic properties within hydrogeologic units during 

simulation of predevelopment and groundwater development.

Conceptual and numerical models that were developed 

in this study were compared to results from previous 

investigations. Many comparisons were to results from the 

Death Valley Regional Flow System version 2 (DVRFS.v2) 

model because this study supersedes the DVRFS.v2 project.

Description of Study Area

The study area comprises the PMOV (940,000 acres), 

AFFCR (1,480,000 acres), Ash Meadows (2,840,000 acres), 

and PDVS (1,460,000 acres) groundwater basins (Fenelon 

and others, 2016). The four groundwater basins are in Clark, 

Lincoln, and Nye Counties, southern Nevada, and Inyo and 

San Bernardino Counties, southern California (fig. 1). In-place 

recharge (Fenelon and others, 2016) principally occurs in 

Pahute Mesa; Spring Mountains; Timber Mountain; and 

Belted, Groom, Pahranagat, and Sheep Ranges. Land-surface 

altitudes exceed 6,000 ft in these highland areas, which are in 

the northern and eastern quadrants of the study area. Natural 

discharge occurs primarily in the Ash Meadows discharge 

area, Lower Amargosa area, Death Valley, Oasis Valley, 

and Pahrump Valley, which are in the southern and western 

quadrants of the study area. Altitudes range from –282 ft in 

Death Valley to 11,916 ft in the Spring Mountains.

The study area mostly is isolated from surrounding 

groundwater basins by low-permeability boundaries and 

groundwater divides (Fenelon and others, 2016). About 290 

mi of the 460 mi perimeter of the study area coincides with 

low-permeability rocks. About 80 mi of boundary through 

carbonate rocks in the Spring Mountains and Sheep Range are 

classified as low permeability because of the occurrence of 

high-altitude springs. Greater than 80 mi of low-permeability 

boundary coincides with the floor of Death Valley. Potentially 

permeable rocks are mapped north of Kawich, Emigrant, and 

Tikaboo Valleys (Heilweil and Brooks, 2011), but flow across 

these boundaries is expected to be limited. Flows of less than 

1,000 acre-ft/yr into Kawich Valley have been estimated 

(Blankennagel and Weir, 1973; Fenelon and others, 2016). 

Penoyer Valley north of Emigrant and Tikaboo Valleys has 

been interpreted as a closed basin (Harrill and others, 1988). 

Potential flow between Tikaboo and Pahranagat Valleys is 

least certain, with previous estimates ranging from 5,000 

acre-ft/yr into the study area (Winograd and Thordarson, 

1975) to 800 acre-ft/yr out of the study area (Belcher and 

Sweetkind, 2010, appendix 2).
6 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

The climate of the study area is arid to semi-arid, 

characteristic of a high desert region. The climate is 

characterized by hot summers and mild winters, large 

fluctuations in daily and annual temperatures, and low 

precipitation and humidity. Average summertime maximum 

temperatures at Furnace Creek are 120 °F (National Climatic 

Data Center, 2017), and average wintertime minimum 

temperatures on Mount Charleston are about 20 °F (National 

Climatic Data Center, 2017). Average annual precipitation in 

the study area ranges from about 2 in. in Death Valley to about 

24 in. on Mount Charleston (National Climatic Data Center, 

2017). Precipitation occurs primarily in late autumn through 

early spring and in mid-summer. Precipitation falls primarily 

as rain, and during the winter months at high altitudes, as 

snow. Most streams in the study area are ephemeral and flow 

only for brief periods after infrequent intense rainfall or during 

and shortly after spring snowmelt.

Previous Investigations

Regional groundwater models were first developed in the 

1980s to estimate potential transport of radionuclides from 

proposed radioactive waste disposal beneath Yucca Mountain 

(Waddell, 1982; Rice, 1984). These models were areally 

extensive because, at the time, known discharge areas and 

assumed recharge areas were separated by more than 50 mi 

(Winograd and Thordarson, 1975) and boundaries between 

groundwater basins were uncertain. In numerical models 

by Waddell (1982) and Rice (1984), simulated groundwater 

flow from Yucca Mountain discharged primarily to Franklin 

Lake (Alkali Flat in Czarnecki and Waddell, 1984) because 

available discharge estimates totaled 10,000 acre-ft/yr (Walker 

and Eakin, 1963). Revised Franklin Lake discharge estimates 

from field measurements and satellite imagery were about 

1,000 acre-ft/yr (Laczniak and others, 2001). This altered the 

conceptual model of Franklin Lake from being the primary 

discharge area downgradient of Yucca Mountain to a mostly 

irrelevant discharge area (Fenelon and others, 2016).

Subsequent regional groundwater models were developed 

to estimate potential transport of radionuclides from Yucca 

Mountain (D’Agnese and others, 1997) and underground 

nuclear tests (IT Corporation, 1997). Areal extents of these 

subsequent models increased relative to Waddell (1982) so that 

uncertainty of boundaries between groundwater basins could 

be investigated (fig. 2). Simulated groundwater-flow paths 

and velocities from these revised models remained uncertain 

mostly because uncertainties in discharge estimates remained.

Regional Models—1982–97

The four regional models (Waddell, 1982; Rice, 1984; 

D’Agnese and others, 1997; IT Corporation, 1997) were 

calibrated to markedly different estimates of predevelopment 

discharge. Differences in model extents (fig. 2) prohibit 

comparison of discharge estimates from some discharge 

areas between models, such as discharges in the PDVS 

groundwater basin (fig. 1). Comparisons are possible for 

predevelopment discharges from Ash Meadows, AFFCR, and 

PMOV groundwater basins. Total predevelopment discharges 

from these three groundwater basins for the four regional 

models ranged from 34,400 to 82,000 acre-ft/yr (table 1). 

Some differences can be attributed to likely double counting 

of spring discharge and groundwater evapotranspiration. 

Groundwater pumping also was simulated erroneously in 

steady-state models where depletion of storage is a substantial 

part of the water budget (Rice, 1984; D’Agnese and others, 

1997). Legitimate differences resulted from uncertainties 

in discharge estimates that required better measurements to 

reduce uncertainties (Waddell, 1982; IT Corporation, 1997).

Regional Investigations—1998–2004

A series of investigations were initiated by the USGS 

to address inadequacies of the existing regional models and 

develop another regional model, Death Valley Regional 

Flow System version 1 model (DVRFS.v1; Belcher, 2004; 

Belcher and Sweetkind, 2010). These investigations resulted 

in about three dozen publications from 1998 to 2004 that 

mapped geologic features, measured hydrologic components, 

and developed hydrologic models. Geologic cross sections 

were interpreted from mapped exposures, borehole data, 

and geophysical mapping of aeromagnetic, gravity, and 

seismic anomalies (Sweetkind and others, 2001). Hydrologic 

components such as predevelopment discharge, pumping, 

water levels, and aquifer-test results were defined better 

with additional measurements and scrutiny of existing 

measurements. Hydrologic models were developed to estimate 

recharge and simulate groundwater flow.

Predevelopment Discharge Investigations

Multiple investigations measured natural discharges 

to support the DVRFS.v1 model. Discharges from the Ash 

Meadows discharge area and Oasis Valley were defined well 

from 18, multiyear, micrometeorological measurement sites 

where groundwater discharge by evapotranspiration (ETGW) 

was estimated (Laczniak and others, 1999; Reiner and others, 

2002). Discharges from Chicago Valley, California Valley, 

Franklin Well area, Franklin Lake, Shoshone-to-Tecopa area, 

and Stewart Valley were refined with ETGW rates extrapolated 

from Oasis Valley and Ash Meadows discharge areas 

(Laczniak and others, 2001). Discharges from Death Valley 

were estimated similarly with a site-specific investigation 

that measured ETGW rates with four micrometeorological 

measurement sites (DeMeo and others, 2003). Discharge from 

100,000 acres of playa in Death Valley remained uncertain 

because annual playa ETGW rates less than 0.3 ft were within 

the measurement error of the Bowen-ratio approach (Jackson 

and others, 2018).
Introduction 7

sac19-4233_fig 02

95

395

6

6

95

93

15

373 190

127

318

375

582

Lida

Hiko

Alamo

Tecopa

Rachel

Beatty

Tonopah

Pahrump

Mercury

Shoshone

Goldfield

Warm

Springs

Las

Vegas

Furnace

Creek

Amargosa

Valley

Scottys

Junction

Amargosa River Amargosa River

Forty mile WashForty mile Wash

Amargosa River Amargosa River

Chin a Ranch

Wash

Golden Gate Range

Coal Valley

Seaman Range

White River Valley

Pahranagat Valley

Sixmile 

Flat

Silurian 

Valley

Kingston 

Range

Sarcobatus 

Flat

Stonewall 

Mountain

Stonewall 

Flat

Stone

Cabin

Valley 

Kawich Range Kawich Range

Reveille Valley

Reveille Range

Railroad Valley

Quinn Canyon Range

Sand 

Spring 

Valley

Cactus 

Flat

Pancake 

Range

Garden Valley

Emigrant 

Valley

Tikaboo 

Valley

Desert 

Valley

Black 

Mountain

Panamint Range

Owlshead 

Mountains

Panamint Valley

Indian 

Wells 

Valley Searles 

Valley

Granite Mountains

Avawatz 

Mountains

Death Valley

Grapevine Mountains

Death Valley

Cottonwood Mountains

Saline Valley

Saline 

Range

Eureka Valley

Last Chance Range

Slate Ridge

Lida Valley

Palmetto

Mountains

Silver 

Peak 

Range

Clayton 

Valley

Weepah 

Hills

Monte 

Cristo Range

Cirac 

Valley San Antonio 

Mountains

Ralston Valley

Monitor Range

Halfpint Range

Spotted Range

Eleana Range

Cactus Range

Pahute Mesa

Oasis Valley

Belted Range

Funeral Mountains

Death Valley

Amargosa Desert

Groom 

Range

Mesquite

Valley

LINCOLN CO.

CLARK CO.

NYE CO.

CALIFORNIA

NEVADA

INYO CO.

SAN BERNADINO CO.

Indian

Springs

Black Mountains

Greenwater Range

Spring Mountains

Pahranagat Range

Sheep Range

Desert Range

Pintwater Range

Specter Range

Chicago Valley

Nopah Range

Gold 

Flat Kawich

Valley

Yucca

Flat

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

California

Valley

Las Vegas

Valley

Dumont

Dunes

Rest ni g Spring Range

ESMERALDA CO.

Devils Hole 

EXPLANATION

Model domain extent

Waddell (1982)

Rice (1984)

D’Agnese and others (1997)

IT Corporation (1997)

Belcher (2004)

Area of DV3 model—groundwater model used in this 

study

Nevada National Security 

Site boundary and internal 

operations area 

37°

38°

36°

117° 116° 115°

0 25 MILES

0 25 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

Model

areas

Study 

area

Figure 2. Areal extent of previous regional groundwater models and the regional model [Death Valley version 3 (DV3)] 

used in this study, Nevada and California.
8 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 1. Predevelopment discharge estimates from previous and current investigations for Alkali Flat–Furnace 

Creek Ranch, Ash Meadows, and Pahute Mesa–Oasis Valley groundwater basins, Nevada and California, 1982–2018.

[Model: 2D-FD, two-dimensional finite difference; 2D-FE, two-dimensional finite element; DVSS1, Death Valley steady-state version 1 

model; IT, IT Corporation; DVSS2, Death Valley steady-state version 2 model; DVRFS.v1, Death Valley Regional Flow System version 

1 model; DVRFS.v2, Death Valley Regional Flow System version 2 model; DV3, Death Valley version 3 model. AFFCR: Alkali Flat–

Furnace Creek Ranch. PMOV: Pahute Mesa–Oasis Valley]

Year Model Citation Groundwater discharge (acre-feet per year)

AFFCR Ash Meadows PMOV Total

1982 2D-FE Waddell, 1982 15,600 16,800 2,000 34,400

1984 2D-FD Rice, 1984 20,000 50,000 4,000 74,000

1997 DVSS1 D’Agnese and others, 1997 40,800 36,900 4,300 82,000

1997 IT IT Corporation, 1997 23,000 31,200 6,500 60,700

2002 DVSS2 D’Agnese and others, 2002 14,000 18,900 5,700 38,600

2004 DVRFS.v1 Belcher, 2004 8,500 18,500 6,000 33,000

2010 DVRFS.v1 Belcher and Sweetkind, 2010 8,500 18,500 6,000 33,000

2017 DVRFS.v2 Belcher and others, 2017 8,500 18,500 6,000 33,000

2018 DV3 This report 7,500 19,000 6,000 32,500

Changes in predevelopment discharge estimates 

substantially affected simulated transport results. For example, 

Franklin Lake was interpreted as the primary discharge area 

from the AFFCR groundwater basin with an initial estimate of 

10,000 acre-ft/yr (Walker and Eakin, 1963), which was double 

the estimated discharge from the Furnace Creek area (Waddell, 

1982; Czarnecki and Stannard, 1997). Revised discharge 

estimates from Franklin Lake totaled 1,000 acre-ft/ yr, 

where 25 percent discharged from the playa (Laczniak and 

others, 2001). ETGW rates of 0.17 ft/yr for playas likely were 

overestimated and better approximated as near 0 ft/yr (Jackson 

and others, 2018). Discharge from Franklin Lake is best 

interpreted as less than 700 acre-ft/yr because most of the 

discharge is local recharge derived from flooding events on the 

Amargosa River, not regional discharge. Reduced discharge 

estimates changed Franklin Lake from being interpreted as 

a primary receptor to an improbable terminus for potential 

transport from Yucca Mountain.

Hydraulic-Property and Water-Use Investigations

Aquifer-test results were compiled, and groundwater 

use was inventoried to improve regional datasets in support 

of the DVRFS.v1 model. A total of 377 transmissivity 

estimates from aquifer tests in southern Nevada and California 

were compiled (Belcher and others, 2001, appendix A). 

Transmissivity estimates were normalized to hydraulic 

conductivities by assuming that contributing thicknesses 

equaled screen lengths so that hydraulic conductivities could 

be classed by hydrogeologic units. Estimated pumping for the 

DVRFS.v1 model was an interpretive effort because minimal 

reporting existed prior to 1950 and permitted water rights are 

not correlated directly with wells (Moreo and others, 2003). 

Annual pumping volumes and uncertainty were estimated for 

9,300 wells in the extent of the DVRFS.v1 model.

Hydrogeologic Framework

A hydrogeologic framework model also was developed 

that was intended to improve the DVRFS.v1 groundwater 

model. The volume within the hydrogeologic framework was 

differentiated into hydrogeologic units on the basis of similar 

geologic and hydraulic properties (Winograd and Thordarson, 

1975; Laczniak and others, 1996; Faunt, Sweetkind, and 

Belcher, 2010; Fenelon and others, 2010). Hydrogeologic 

units were assumed to represent volumes of fairly uniform 

hydraulic properties in structurally similar zones (Faunt, 

Blainey, and others, 2010, p. 280). Hydraulic properties were 

distributed throughout the DVRFS.v1 model by assigning 

a single value to each zone in a hydrogeologic unit (Faunt, 

Blainey, and others, 2010).

An unexpected result from another supporting 

investigation (Belcher and others, 2002) of the DVRFS.v1 

model was that hydraulic conductivities were predicted and 

constrained poorly by hydrogeologic units in the DVRFS.

v1 hydrogeologic framework. Probability distributions of 

hydraulic conductivity, which were estimated from aquifertest results, were computed for 18 of 27 hydrogeologic units 

in the DVRFS.v1 hydrogeologic framework. Hydraulic 

conductivities were highly heterogeneous rather than 

uniform for all analyzed hydrogeologic units. Hydraulic 

conductivities in each hydrogeologic unit ranged from three 

to seven orders of magnitude (fig. 3). The geometric mean 

hydraulic conductivity of the alluvial confining unit exceeded 

the geometric mean hydraulic conductivity of the alluvial 

aquifer, which contradicts conceptual models of aquifers and 

confining units (Belcher and others, 2002, table 1). Highly 

heterogeneous hydraulic conductivities contradict assumptions 

that hydrogeologic units in DVRFS.v1 approximate uniform 

hydraulic conductivities (Faunt, Blainey, and others, 2010, p. 

280).
Introduction 9

sac19-4322_fig 03

Carbonate Aquifer 

(42)

Alluvial Aquifer 

(52)

Younger Volcanics 

(15)

Tertiary Volcanics 

(172)

Older Volcanics

(46)

Sedimentary Confining Unit

(16)

Alluvial Confining Unit 

(15)

Clastic Confining Unit 

(12)

Intrusive Confining Unit 

(7)

Hydrogeologic units

1×10−8 1×10−7 1×10−6 1×10−5 1×10−4 1×10−3 1×10−2 1×10−1 1×100 1×101 1×102 1×103 1×104

Hydraulic conductivity, in feet per day

(Modified from Belcher and others, 2002)

95% confidence interval 

Geometric mean

Minimum Maximum

Number of transmissivity estimates for 

each rock type is shown in parentheses. 

EXPLANATION

Sedimentary Confining Unit

 (16)

Figure 3. Minimum, maximum, geometric mean, and 95-percent confidence interval of log-hydraulic conductivities in 9 

hydrogeologic units in the Death Valley Regional Flow System version 2 model framework using 377 hydraulic-conductivity 

estimates, Nevada and California.

DFRVS.v1 Model

The DVRFS.v1 model was developed to supply boundary 

conditions to CAU models that simulated radionuclide 

transport beneath the NNSS, and to simulate water-level 

changes in critical areas from pumping. These development 

goals were reported as appropriate uses of the DVRFS.v1 

model: “The model can provide boundary conditions for 

the development of local-scale models, such as those being 

developed by the Department of Energy...” (Belcher, 2004, 

p. 348; Belcher and Sweetkind, 2010, p. 340) and “[t]he 

model can be used for examining the effects of continued 

or increased pumpage on the regional ground-water flow 

system to effectively manage ground-water resources within 

conflicting land-use management policies.” (Belcher, 2004, p. 

349; Belcher and Sweetkind, 2010, p. 341.)

Boundary conditions from the DVRFS.v1 model that 

were applied to a local-scale CAU model of the carbonate 

aquifer beneath Yucca Flat were not adequate for their stated 

purpose. The DVRFS.v1 model simulated a groundwaterflow rate of 14,000 acre-ft/yr into northern Yucca Flat through 

low-permeability shale, quartzite, granite, marble, and siltstone 

(Belcher and Sweetkind, 2010). Applying 14,000 acre-ft/yr 

as the northern boundary condition for the Yucca Flat CAU 

model resulted in rapid groundwater velocities, large extents 

of simulated tritium plumes that were not supported by tritium 

data, and model-estimated hydraulic properties that exceeded 

aquifer-test results (Navarro-Intera, LLC, 2013). The 14,000 

acre-ft/yr of northern flow is erroneously large because 

predevelopment flow through Yucca Flat ranges from 350 and 

1,000 acre-ft/yr (Winograd and Thordarson, 1975; Harrill and 

others, 1988; Fenelon and others, 2016), and estimated flow 

through low-permeability rocks in northern Yucca Flat is less 

than 40 acre-ft/yr (Winograd and Thordarson, 1975, p. C93).

Groundwater resources within 25 mi of Devils Hole

have been managed with an empirical rule (Nevada State 

Engineer, 2008b), instead of using the DVRFS.v1 model. The 

State Engineer administers water resources in Nevada and 

designated Amargosa Desert hydrographic area 230 in 1979. 

Nevada State Engineer Order No. 724 manages pumping 

to maintain a minimum pool elevation in Devils Hole. The 
10 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

empirical rule was developed in response to proposed changes 

in points of diversion, where the protestant was the National 

Park Service (Nevada State Engineer, 2008a). The National 

Park Service also cooperatively developed and funded the 

DVRFS.v1 model (Belcher, 2004, p. 7) because conflicting 

land uses were anticipated (Belcher, 2004, p. 349). The 

protestant estimated effects of proposed changes in pumping on 

water levels in Devils Hole with a Theis analysis (Nevada State 

Engineer, 2008b), despite having cooperatively developed and 

funded the DVRFS.v1 model.

DVRFS.v2 Model

A revised regional model, DVRFS.v2, was developed to 

update the DVRFS.v1 model with new data and interpretations 

(Belcher and others, 2017). Two primary purposes of the 

DVRFS.v2 model were stated: “... (1) inform definition of 

boundary conditions for the Underground Test Area (UGTA) 

Corrective Action Units (CAUs) on the NNSS, (2) evaluate the 

effects of changes in groundwater-system fluxes, regardless 

of whether the changes are natural or human-induced...” 

(Belcher and others, 2017, p. 3). Revisions to the DVRFS.

v1 model included altering the hydrogeologic framework, 

estimating annual variations in recharge, extending the 

simulated period 5 years to 2003, comparing transmissivities 

and water-budget terms in the objective function, and 

distributing hydraulic properties with pilot points in some 

basin-fill units. Despite revisions, the DVRFS.v2 model is 

inadequate for its reported purposes.

Simulated flow through Yucca Flat remained unrealistic 

even though flow into northern Yucca Flat was reduced from 

14,000 to 1,400 acre-ft/yr between the DVRFS.v1 and DVRFS.

v2 models, respectively (Navarro-Intera, LLC, 2013, table 

5-7). The DVRFS.v2 model simulated 7,700 acre-ft/yr (300 

kg/s) across the southern edge of the Yucca Flat–Climax Mine 

CAU model of carbonate rocks (Navarro-Intera, LLC, 2013, 

table 5-7). Regional water-balance analyses limited flow from 

southern Yucca Flat to about 1,000 acre-ft/yr (Winograd and 

Thordarson, 1975; Fenelon and others, 2016). Groundwaterflow estimates from hydraulic gradients and aquifer-test results 

ranged from 240 to 970 acre-ft/yr (Navarro, 2016a) between 

wells ER-7-1 and ER-6-1-2 main, where these estimates 

represent groundwater flow from approximately two-thirds 

of the Yucca Flat hydrographic area. UGTA investigators 

concluded: “This limit on flux through the high-transmissivity 

eastern corridor suggests that several models documented in 

N-I (2013a) [Navarro-Intera, LLC, 2013]—including the base 

case and many Null Space Monte Carlo (NSMC) results with 

northern boundary fluxes greater than 50 kg/s [1,300 acre-ft/

yr]—are unrealistic.” (Navarro, 2016a, p. 24.)

The DVRFS.v2 model poorly explains effects of natural 

changes and pumping on water levels in Devils Hole and 

spring discharges in the Ash Meadows discharge area, which 

precludes analyzing effects of either stress with the DVRFS.

v2 model. Measured water levels in carbonate rocks naturally 

fluctuate from 0.5 to 3 ft in wells and in Devils Hole, where 

these natural changes correlate with fluctuations in cumulative 

departure from mean precipitation (Fenelon and Moreo, 2002, 

p. 51). The DVRFS.v2 model simulated less than 0.02 ft of 

natural water-level changes in Devils Hole (fig. 4). Simulated 

and measured water-level changes notably differ in Devils 

Hole, where maximum water-level declines from pumping, 

or drawdown, in the DVRFS.v2 model were simulated about 

30 years after maximum measured drawdown occurred 

(fig. 4). Measured spring discharges of 1,400 acre-ft/month 

(10,700 gal/min) decreased 34 percent during August 1971 in 

response to pumping of about 1,000 acre-ft/month in the Ash 

Meadows discharge area (Dudley and Larson, 1976, p.22). 

Simulated capture in the DVRFS.v2 model from all springs 

and evapotranspiration areas totaled less than 1 percent of the 

predevelopment discharge, in response to pumping in the Ash 

Meadows discharge area.

The stated goals of informing boundary conditions and 

estimating the effects of groundwater pumping were not 

achieved in the DVRFS.v1 and DVRFS.v2 projects because 

geologic differences were emphasized in the hydrogeologic 

frameworks and groundwater models. Results from the 

DVRFS.v1 and DVRFS.v2 projects indicate the need for 

hydrology to inform the hydrogeologic framework by 

empirically testing hydrogeologic units with results from 

aquifer tests. Achieving the stated goals requires a new 

approach that emphasizes hydrologic results.

Approach

The study area, purpose, and approach of this project 

differ from the DVRFS.v1 and DVRFS.v2 studies. The study 

area of this project is about 6,720,000 acres, which is less than 

one-third the areal extent of the approximately 24,710,000-

acre DVRFS.v2 model (fig. 2). Because the study area does 

not encompass the entire Death Valley regional flow system 

(Harrill and others, 1988), the general descriptor for this 

project has been simplified to Death Valley version 3 (DV3).

The DV3 study area encompasses the AFFCR, Ash 

Meadows, PMOV, and PDVS groundwater basins to address 

the study objectives. Potential radionuclide transport from 

historical underground nuclear tests at the NNSS occurs in 

the AFFCR, Ash Meadows, and PMOV groundwater basins. 

Groundwater development occurs in all four groundwater 

basins; however, extensive development occurs in the 

AFFCR, Ash Meadows, and PDVS groundwater basins. The 

outer boundaries of groundwater basins in the DV3 study 

area mostly are separated from surrounding groundwater 

basins outside the study area by no-flow boundaries (Fenelon 

and others, 2016). However, within the DV3 study area, 

groundwater-basin boundary uncertainty needs to be addressed 

for the boundaries between the four groundwater basins. 

Groundwater-basin boundary uncertainty affects estimation of 

potential radionuclide transport from underground tests, and 

degrees of hydraulic connection between pumping centers 

and areas of interest, such as Devils Hole, across groundwater 

divides.
Introduction 11

sac19-4322_fig 04

−4

−2

0

2

1930 1940 1950 1960 1970 1980

Year

1990 2000 2010 2020

Water-level change, in feet

DVRFS.v1, Pumping

DVRFS.v2, Natural changes

DVRFS.v2, Natural changes 

 and pumping

Measured

EXPLANATION

Figure 4. Measured and simulated water-level changes 

in Devils Hole from the Death Valley Regional Flow System 

versions 1 and 2 (DVRFS.v1 and DVRFS.v2) models, Nevada 

and California, 1930–2018.

Predevelopment conditions, historical groundwater 

development, and potential pumping effects from future 

development were simulated with multiple, stress-response 

groundwater models that honor hydraulic constraints. Stressresponse models are groundwater models that simulate an 

identifiable stress within the aquifer system. Average recharge 

is the stress during steady-state, predevelopment conditions 

and is better defined than time-varying recharge. Pumping for 

groundwater development is the stress in transient models and 

is highly identifiable relative to other hydraulic stresses. The 

primary assumption of the stress-response approach is that 

differentiating natural (recharge) and anthropogenic (pumping) 

stresses introduces less errors than compensating errors in 

a single model that attempts to simultaneously simulate all 

stresses.

Developing a set of stress-response models simplifies 

estimation of hydraulic properties because structural errors 

are easier to discern and remove where responses to steadystate and transient stresses are separated. A set of stressresponse models also better addresses multiple questions than 

a single groundwater model because boundary conditions 

are tailored to the effects of each stress. For example, 

models simulating both predevelopment flow (steady-state) 

and groundwater development (transient) should inform a 

calibrated transmissivity distribution. Spring discharge is best 

specified as a constant value for calibration to predevelopment 

conditions but must decrease in response to pumping as 

groundwater development is simulated (Halford and Plume, 

2011). Spring discharge can be simulated advantageously 

as a specified discharge in a steady-state model and as a 

head-dependent discharge in a groundwater-development 

model. Both models have common hydraulic properties and 

are calibrated simultaneously so that all observations inform 

an estimated transmissivity distribution (Garcia and others, 

2017).

Predictive utility of the DV3 model depends on 

plausibility of calibrated recharge, transmissivity, specificyield, and specific-storage distributions. Plausibility 

increases as simulated results better match as many relevant 

observations and concepts as possible. Predevelopment 

flow was simulated and compared to water-level altitudes, 

discharges, and transmissivity estimates from aquifer tests. 

Groundwater development in AFFCR, Ash Meadows, PMOV, 

and PDVS groundwater basins was simulated as changes from 

predevelopment and compared to measured changes in water 

levels and spring discharges. Pumping from well ER-6-1-2 

main during a large-scale, multiple-well aquifer test (MWAT) 

in Yucca Flat also was simulated, where simulated drawdowns 

were compared to drawdown estimates in observation wells 

located 0–33 mi from the pumped well. Four stress-response 

models simulated predevelopment conditions, groundwater 

development in the PDVS groundwater basin, groundwater 

development in the PMOV, AFFCR, and Ash Meadows 

groundwater basins, and the large-scale MWAT (table 2). All 

models shared common recharge, transmissivity, specificyield, and specific-storage distributions, as needed, and were 

calibrated simultaneously.

Advective flow from nuclear tests and effects of 

groundwater pumping were estimated with separate 

models that were appropriate for addressing each question. 

Advective flow from selected nuclear tests was estimated 

with the DV3-SS model because flow paths from these 

tests do not extend into pumping areas (table 2). Potential 

effects of historical (1913–2018) and future (2019–2100) 

groundwater pumping were simulated directly as change 

from predevelopment conditions (Leake and others, 2010) 

with another model, DV3-PRED. This model is discretized 

temporally to annual pumping changes in all groundwater 

basins from 1913 to 2100. Directly simulating potential 

effects of pumping with a separate predictive model has been 

effective elsewhere in Nevada (Halford and Plume, 2011).
12 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 2. Groundwater models developed for Death Valley version 3 model (DV3) project.

Groundwater model Description Purpose

DV3-SS Steady-state model of predevelopment flow Calibration and transport 

estimates

DV3-AM-AFFCR Transient superposition model of groundwater development in the Alkali Flat–Furnace 

Creek Ranch, Ash Meadows, and Pahute Mesa–Oasis Valley groundwater basins

Calibration

DV3-ER612 Well ER-6-1-2 main aquifer test, 2004 Calibration

DV3-PDVS Transient superposition model of groundwater development in the Pahrump to Death 

Valley South groundwater basin

Calibration

DV3-PRED Capture-limited model for predicting pumping effects Predict pumping effects

Geology

Geologic units were formed by magmatic activity, 

volcanism, and depositional processes in the study area. These 

rocks subsequently have been uplifted, thrusted, offset, and 

deformed. Depositional, magmatic, volcanic, and tectonic 

processes have juxtaposed geologic units into a complex threedimensional framework that affects groundwater flow. The 

geologic history is divided into six periods of deposition and 

tectonic deformation:

1. Precambrian and Paleozoic marine and non-marine 

deposition;

2. Late Paleozoic to Early Cenozoic folding, thrusting, and 

strike-slip faulting;

3. Mesozoic intrusion;

4. Cenozoic volcanism;

5. Cenozoic normal and strike-slip faulting; and

6. Cenozoic basin-fill deposition (table 3).

Precambrian and Paleozoic marine and orogenic 

processes resulted in two major sedimentation sequences of 

siliciclastic and carbonate rocks (Winograd and Thordarson, 

1975; Laczniak and others, 1996; Slate and others, 2000; 

Sweetkind and others, 2010). The continental margin of the 

southwestern United States intersected the study area from the 

Neoproterozoic to Devonian (Sweetkind and others, 2010). 

Marine sedimentary rocks, primarily siltstones, were deposited 

from Neoproterozoic to Lower Cambrian (table 3), where 

deposits thicken westward in the study area. The siliciclastic 

rocks are overlain by thick sequences of Middle Cambrian 

to Devonian carbonate rocks. From the Late Devonian to 

Mississippian, siliciclastic rocks—predominantly shales and 

argillites—interrupted marine carbonate deposition in the 

eastern part of the study area. Siliciclastic sediments were 

derived from uplifted areas north of the study area (Sweetkind 

and others, 2010). Marine carbonate deposition continued 

from the Late Mississippian to Permian (table 3).

Precambrian and Paleozoic rocks were subjected to 

compressional tectonic forces from the Late Paleozoic to 

Early Cenozoic. Siliciclastic and carbonate rocks were 

offset by regional thrust faulting (fig. 5), which emplaced 

Neoproterozoic to Lower Cambrian siliciclastic rocks over 

younger Paleozoic rocks (Sweetkind and others, 2010). 

Many mountain ranges have exposed thrust faults, including 

the Belted, Eleana, Specter, Resting Spring, and Nopah 

Ranges, as well as Bare Mountain and the Spring and Funeral 

Mountains (fig. 5; Sweetkind and others, 2010). Thrust 

faulting displaced rocks laterally more than 10 mi away 

(Winograd and Thordarson, 1975). Siliciclastic and carbonate 

rocks also were subjected to folding and strike-slip faulting 

(Laczniak and others, 1996). Compressional tectonics have 

formed broad anticlines and synclines in the Precambrian and 

Paleozoic sequence within the Ash Meadows groundwater 

basin. Mesozoic rocks mostly are absent because of uplift and 

erosion of Precambrian and Paleozoic rocks (Sweetkind and 

others, 2010). Therefore, Mesozoic rocks are minor and occur 

as localized granitic intrusions.

Volcanic and associated sedimentary rocks formed during 

the Cenozoic (table 3). From the Oligocene to Miocene, 

thick sequences of volcanic rocks were deposited by calderaforming eruptions in the southwestern Nevada volcanic field, 

located in the northwestern part of the study area (Byers and 

others, 1976; Christiansen and others, 1977; Sawyer and 

others, 1994; Laczniak and others, 1996; Prothro and Drellack, 

1997). Volcanic centers within the southwestern Nevada 

volcanic field caldera complex (fig. 5) erupted rhyolitic-todacitic lava flows, variably welded ash-flow tuffs, ash-fall 

tuffs, and volcaniclastic rocks (Winograd and Thordarson, 

1975; Laczniak and others, 1996; Sweetkind and others, 

2010). From the Miocene to Pliocene, localized rhyolitic and 

basaltic lava flows erupted from the central Death Valley 

volcanic field in Greenwater Valley (Sweetkind and others, 

2010). During the Holocene, localized basaltic lava flows 

erupted from five cinder cones in the Crater Flat volcanic field 

(Wells and others, 1990).
Geology 13

Table 3. Major lithology and occurrence descriptions of hydrogeologic units in the study area, as defined in the Death Valley Regional 

Flow System version 2 hydrogeologic framework, Nevada and California.

[Abbreviations: AM, Ash Meadows groundwater basin; AFFCR, Alkali Flat-Furnace Creek Ranch groundwater basin; CDVVF, Central Death Valley volcanic 

field; PDVS, Pahrump to Death Valley South groundwater basin; PMOV, Pahute Mesa-Oasis Valley groundwater basin; SAMM, Southern AMargosa Model; 

SWNVF, southwestern Nevada volcanic field. Table summarizes information obtained from Noble and others (1964, 1984); Blankennagel and Weir (1973); 

Winograd and Thordarson (1975); Byers and others (1976); Christiansen and others (1977); Simonds (1989); Sawyer and others (1994); Laczniak and others 

(1996); Prothro and Drellack (1997); Slate and others (2000); Sweetkind and others (2010); Taylor and Sweetkind (2014)] Era Period

Abbreviation Hydrogeologic 

unit Major lithology Occurrence

Tertiary - Quaternary

Cenozoic basin-fill and volcanic sediments (unconsolidated)

YAA Younger alluvial 

aquifer

Coarse-grained alluvium and colluvium with minor 

debris-flow and eolian sediments. Proximal to distal fan 

alluvial deposits grade from gravels and sands to silts 

and clays, whereas fluvial deposits consist of gravel and 

sand. Debris flows are poorly sorted coarse- and finegrained deposits. Eolian deposits are well-sorted dunal 

sands or sand sheets. 

Saturated basin fill beneath ephemeral channels, such as Amargosa River and Fortymile 

Wash, and beneath depositional basins, such as 

Oasis, Death, and Pahrump Valleys, Amargosa 

Desert, and Crater, Yucca, and Frenchman Flats 

[AFFCR, AM, PDVS, PMOV].

OAA Older alluvial 

aquifer 

YACU Younger alluvial 

confining unit 

Fine-grained playa and lacustrine deposits. Deposits 

consist of alternating sequences of fine sand, silt, and 

clay. Playa sediments are imbued with salt and capped 

by a salt crust.

Saturated basin-axis and playa deposits beneath 

valley floors, such as Death and Pahrump Valleys, Amargosa Desert, and Yucca and Frenchman Flats [AFFCR, AM, PDVS, PMOV].

OACU Older alluvial confining unit 

LA Limestone aquifer Lacustrine and spring deposits of limestone and 

travertine.

Localized saturated units in Amargosa Desert 

[AFFCR].

LFU Lava-flow unit Localized rhyolitic and basaltic lava flows, cinder cones, 

and nonwelded tuff. Rocks erupted from CDVVF.

Unit typically located above water table, except 

for localized lava flows in Amargosa Desert and 

Crater Flat [AFFCR].

Cenozoic

Tertiary

YVU Younger volcanicrock unit Localized volcanic tuffs. Unit typically located above water table, except 

for localized tuffs in Desert Range [AM].

SmAA Coarse-grained units 

from SAMM

Coarse-grained (gravel and sand) basin-fill deposits, 

basaltic lava flows, and limestones mapped in SAMM.

Saturated basin fill beneath Amargosa Desert, 

Crater and Jackass Flats, and the Ash Meadows 

discharge area [AFFCR, AM].

SmCU Fine-grained units 

from SAMM

Fine-grained (silt and clay) basin-fill deposits mapped 

in SAMM.

Saturated basin fill beneath Amargosa Desert, 

Crater and Jackass Flats, and the Ash Meadows 

discharge area [AFFCR, AM].
14 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 3. Major lithology and occurrence descriptions of hydrogeologic units in the study area, as defined in the Death Valley Regional 

Flow System Version 2 hydrogeologic framework, Nevada and California.—Continued Era Period

Abbreviation Hydrogeologic 

unit Major lithology Occurrence

Cenozoic volcanic rocks of the southwestern Nevada volcanic field

TMVA Thirsty CanyonTimber Mountain 

volcanic-rock aquifer 

Variably welded ash-flow tuffs, ash-fall tuffs, rhyolite 

and trachyte lavas and domes, and intracaldera landslide 

breccia with minor nonwelded tuff.

Volcanics erupted from Timber Mountain caldera 

complex and Black Mountain caldera. Unit saturated beneath Pahute Mesa, Oasis Valley, Yucca 

Mountain, and Jackass, Yucca, and Frenchman 

Flats [AFFCR, AM, PMOV].

Cenozoic

PVA Paintbrush volcanicrock aquifer Rhyolitic lavas, variably welded ash-flow tuffs, nonwelded ash-fall tuff, bedded tuff, and fluvially reworked 

tuff. Nonwelded tuffs have argillic, hematitic, silicic, or 

zeolitic alteration.

Volcanics erupted from the Claim Canyon caldera. Unit saturated beneath Pahute Mesa, Yucca 

Mountain, and Jackass, Yucca, and Frenchman 

Flats [AFFCR, AM, PMOV].

Tertiary

CHVU Calico Hills 

volcanic-rock unit 

Variably welded ash-flow tuffs, nonwelded zeolitically 

altered ash-fall and bedded tuffs, rhyolitic lavas, and 

volcaniclastic deposits. 

Volcanics erupted from the Silent Canyon caldera 

complex. Unit saturated beneath Pahute Mesa, 

Yucca Mountain, and Jackass and Yucca Flats 

[AFFCR, AM, PMOV].

WVU Wahmonie volcanicrock unit Biotite-rich nonwelded tuff, andesitic-to-dacitic lavas, 

tuffaceous sandstone, and tuff breccia.

Volcanics erupted from stratovolcanoes in the 

Wahmonie volcanic center near Skull Mountain. 

Unit saturated beneath Jackass and Yucca Flats 

[AFFCR, AM].

CFPPA Crater Flat–Prow 

Pass aquifer 

Rhyolitic-to-andesitic lava flows and variably welded 

ash-flow tuffs. Partly welded to nonwelded tuffs are commonly zeolitized.

Location of source for erupted volcanics 

unknown. Unit saturated beneath Rainier Mesa, 

Yucca Mountain, and Yucca Flat [AFFCR, AM, 

PMOV].

CFBCU Crater Flat–Bullfrog 

confining unit 

Nonwelded and variably welded ash-flow and ash-fall 

tuffs. Nonwelded tuff commonly zeolitized.

Volcanics erupted from the Silent Canyon caldera 

complex. Unit saturated beneath Pahute Mesa 

and Yucca Mountain [AFFCR, PMOV].

CFTA Crater Flat–Tram 

aquifer 

Nonwelded to variably welded ash-flow tuffs. Mostly 

partially welded to nonwelded tuffs with localized areas 

of dense welding.

Volcanics possibly erupted from an unnamed caldera beneath northern Crater Flat. Unit saturated 

beneath Yucca Mountain [AFFCR].

BRU Belted Range unit Rhyolitic lavas and densely welded ash-flow tuffs with 

minor nonwelded (commonly zeolitized) tuff.

Volcanics erupted from Silent Canyon caldera 

complex. Unit saturated beneath Pahute Mesa 

and Yucca Flat [AM, PMOV].

OVU Older volcanic-rock 

unit 

Undifferentiated older volcanic rocks of the SWNVF, 

including lavas, variably welded ash-flow tuffs, zeolitically altered nonwelded tuffs, reworked tuff, and volcaniclastic rocks.

Volcanic rocks erupted from volcanic centers 

either in or north of the SWNVF. Unit saturated 

beneath Pahute and Rainier Mesas, Yucca Mountain, and Yucca and Frenchman Flats [AFFCR, 

AM, PMOV].

Cenozoic volcanic and sedimentary deposits (consolidated)

VSU upper Upper volcanic-sedimentary rock unit Undifferentiated volcanic and sedimentary rocks, including welded and nonwelded tuffs, rhyolitic-to-basaltic 

lava flows, alluvium, colluvium, and eolian, fluvial, and 

lacustrine deposits. Rocks not associated with previously 

defined volcanic and sedimentary units.

VSU upper and VSU lower contain rocks that 

overlie and underlie volcanic rocks of the 

SWNVF, respectively. Outside the SWNVF 

boundary, the division between VSU upper and 

VSU lower is arbitrary. Saturated unit is regionally extensive throughout study area [AFFCR, 

AM, PDVS, PMOV].

VSU lower Lower volcanic-sedimentary rock unit 
Geology 15

Table 3. Major lithology and occurrence descriptions of hydrogeologic units in the study area, as defined in the Death Valley Regional 

Flow System Version 2 hydrogeologic framework, Nevada and California.—Continued Era Period

Abbreviation Hydrogeologic 

unit Major lithology Occurrence

Pre-Cenozoic rocks

Mesozoic - Cenozoic

ICU Intrusive-rock confining unitMesozoic granite, granodiorite, quartz monzonite, and 

tonalite in stocks, dikes, and sills. Cenozoic (Oligocene 

and Miocene) granite, gabbro, and diorite plutons associated with extension and caldera-related volcanism.

Localized stocks in Greenwater, Groom, Kawich, 

and Kingston Ranges, Black Mountains, and 

north of Rainier Mesa and Yucca Flat [AFFCR, 

AM, PMOV, PDVS].

MesozoicTriassic

SCU Sedimentary-rock 

confining unit 

Interbedded sedimentary rocks, including gypsum, 

limestone, calcareous shale, shale, siltstone, sandstone, 

and conglomerate.

Localized unit beneath the Spring Mountains and 

Pahrump Valley [PDVS].

Paleozoic

Mississippian -Permian

UCA Upper carbonaterock aquifer Limestone, dolomite, and calcareous shale. Localized saturated unit above UCCU in western 

Yucca Flat [AM].

Devonian -Mississippian

UCCU Upper clastic-rock 

confining unit 

Quartzite, argillite, conglomerate, sandstone, siltstone, 

and shale with minor limestone. Carbonate and siliciclastic rocks were derived from debris flows and turbidites, 

where sediments grade from coarse to fine from ridges to 

the valley floor.

Localized unit saturated beneath northern Jackass Flats and western and northern Yucca Flat 

[AFFCR, AM].

Cambrian - Devonian

LCA_T1 Lower carbonaterock aquifer 

(thrusted)

Massive dolomite and limestone with minor quartzite, 

chert, shale and calcareous siltstone. LCA includes Mississippian and Pennsylvanian carbonate rocks, where 

these rocks are not separated by UCCU.

Saturated unit occurs beneath the Spring 

Mountains, Sheep Range, Specter Range, Skull 

Mountain, and central Yucca Flat [AFFCR, AM, 

PDVS].

LCA Lower carbonaterock aquifer Massive dolomite and limestone with minor quartzite, 

chert, shale and calcareous siltstone. LCA includes Mississippian and Pennsylvanian carbonate rocks, where 

these rocks are not separated by UCCU.

Saturated unit is regionally extensive throughout 

AM groundwater basin, occurs beneath Amargosa Desert, Pahrump, Chicago, and California 

Valleys, and Spring and Funeral Mountains 

[AFFCR, AM, PDVS].

LCCU_T1 Lower clastic-rock 

confining unit 

(thrusted)

Quartzite, sandstone, siltstone, shale, minor limestone 

and dolomite, and their metamorphic equivalents. Unit 

includes the Pahrump Group and Noonday Dolomite. 

Saturated unit occurs beneath the Spring Mountains, Sheep Range, Specter Range, Funeral 

Mountains, and Rainier Mesa [AFFCR, AM, 

PDVS].

Neoproterozoic era

to Cambrian period

LCCU Lower clastic-rock 

confining unit 

Quartzite, sandstone, siltstone, shale, minor limestone 

and dolomite, and their metamorphic equivalents. Unit 

includes the Pahrump Group and Noonday Dolomite. 

Saturated unit occurs throughout study area 

[AFFCR, AM, PDVS, PMOV].

Precambrian 

eon

XCU Crystalline-rock 

confining unit 

Metamorphosed sedimentary rocks, granite, gneiss, and 

quartzfeldspathic schist.

Saturated unit occurs beneath Funeral and Black 

Mountains [AFFCR, PDVS].
16 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 05

Spotted Range

Yucca

Flat

Pahute Mesa

Groom 

Range

Cactus 

Range

Emigrant 

Valley

Specter

Range

LINCOLN CO.

CLARK CO.

NYE CO.

NEVADA

INYO CO. CALIFORNIA

SAN BERNADINO CO.

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Sheep Range

Pintwater Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat Kawich

Valley

Climax

Mine

Rainier

Mesa

Jackass

Flats

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH

MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Pahra nagat Range

Desert Range

California Valley

Death Valley

Amargosa

Valley

Shoshone

Furnace

Creek

Mercury

Beatty

Tecopa

Pahrump

Indian

Springs

Las

Vegas

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

Jumbled Hills fault zone

Mount

Helen

caldera

Cactus Range

caldera Cathedral

Ridge

caldera

Carrara fault

P

Keane W

Kawich Range West fault

Belted Range fault

Belted Range thrust

Yucca fault

Main fault

PAHRANAGAT SHEAR ZONE

Buckhorn fault

Sheep Basin fault

Gass Peak thrust

Spotted Range fault zone

Rock Valley fault zone

Cane Spring fault

Timber

Mountain

caldera

complex

GrouseCanyoncaldera

CP thrust

Claim 

Canyon 

caldera

Bare Mountain fault

Ammonia 

Tanks 

caldera

Black Mtn 

caldera

THIRSTY CANYON LINEAMENT

Hogback fault

Porter Mine fault

Boundary Canyon fault

Keane Wonder fault

DEATH VALLEY FAULT ZONE

Grand View fault FURNACE CREEK FAULT ZONE

Schwaub Peak thrust

Specter Range thrust Gravity fault

Wheeler Pass thrust

LAS VEGAS VALLEY SHEAR ZONE

STEWART VALLEY - PAHRUMP FAULT ZONE

Resting

thrust

Sheephead fault

Devils Hole 

EXPLANATION

Observation site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Normal fault

Strike-slip fault

Detachment fault

Thrust fault—Sawteeth on 

upthrown side. Dashed 

where inferred

Caldera structural boundary 

—Hachures toward center 

of caldera

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second National 

Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

fault

Maynard Lake

Dumont

Dunes

Figure 5. Major geologic structures, in the study area, Nevada and California.
Predevelopment Groundwater Flow 17

Large-scale normal faulting occurred during and after 

the period of Cenozoic volcanism (Winograd and Thordarson, 

1975; Laczniak and others, 1996; Prothro and Drellack, 

1997; Sweetkind and others, 2010). From the Mid-Tertiary 

to Quaternary, normal faults (fig. 5) formed the Basin and 

Range topography of the Great Basin province. Normal 

faults are the most common structural feature in the study 

area and displacement along normal faults continues today 

(Winograd and Thordarson, 1975). Normal faults typically 

have displaced the Precambrian through Cenozoic section by 

less than 500 ft; however, in some cases, normal faults have 

displaced rocks more than 1,000 ft (Winograd and Thordarson, 

1975). Sedimentary rocks associated with volcanism occur 

throughout the study area, and consist of tuffaceous sandstone 

and siltstone, lacustrine tuff, and claystone.

Cenozoic unconsolidated basin fill occurs throughout 

the study area in intermontane basins (Sweetkind and others, 

2010; Taylor and Sweetkind, 2014). Coarse-grained basin fill 

typically consists of alluvial and colluvial deposits with minor 

fluvial, debris-flow, and eolian deposits. Fine-grained basin 

fill consists of playa and lacustrine sediments. Limestone and 

spring deposits also are present locally.

Interbasin Flow Between Groundwater 

Basins

Interbasin flow is the movement of groundwater across 

groundwater-basin boundaries. Groundwater-basin boundaries 

were delineated by Fenelon and others (2016) to minimize 

interbasin flow between groundwater basins. Therefore, 

interbasin flow is limited to four small areas in the study area. 

Expected flows between groundwater basins were derived 

from Darcy estimates through well-defined features, such as 

basin fill bounded by low-permeability rocks south of Beatty 

and near Eagle Mountain (fig. 6).

Groundwater moves from the Ash Meadows groundwater 

basin to the AFFCR groundwater basin through a 2–5-mi-wide 

corridor around well AD-4 (fig. 6). Permeable basin fill 

contacts permeable carbonate rock along the Gravity fault 

(fig. 5) in the well AD-4 corridor. This is atypical along 

the Gravity fault because, south of the well AD-4 corridor, 

low-permeability basin fill in the AFFCR groundwater basin 

has been juxtaposed against carbonate rocks in the Ash 

Meadows groundwater basin. Groundwater upwells from 

underlying carbonate rocks to overlying basin fill in the well 

AD-4 corridor, and flows through permeable basin fill in the 

Amargosa Desert. Groundwater flows between groundwater 

basins and does not discharge at land surface because shallow 

basin fill is sufficiently permeable in the well AD-4 corridor 

(fig. 6).

Expected predevelopment flow from the Ash Meadows 

to the AFFCR groundwater basin through the well AD-4

corridor ranges from 2,000 (Fenelon and others, 2016) to 

4,000 acre-ft/yr, where the expected flow rate likely is closer 

to 2,000 acre-ft/yr. Expected flow rates were computed from 

Darcy’s Law assuming a hydraulic gradient of 0.01 ft/ft, a 

transmissivity of 2,000 ft2

/d from specific-capacity tests, and a 

corridor width of 2–5 mi.

Groundwater moves from the PMOV groundwater 

basin to the AFFCR groundwater basin through basin fill of 

limited saturated thickness south of Beatty (fig. 6). Basin fill 

underlies the Amargosa River channel and is bounded by lowpermeability rocks from Bullfrog Hills and Bare Mountain. 

Reiner and others (2002) estimated about 100 acre-ft/yr of 

groundwater flow from the PMOV to the AFFCR groundwater 

basins (fig. 6). The Amargosa River is perennial in Beatty 

and about 300 acre-ft/yr of streamflow flows past USGS 

streamgage 10251217 (Amargosa River at Beatty, Nevada). 

Part of this streamflow infiltrates basin fill in the Amargosa 

River channel and recharges the AFFCR groundwater basin 

(Stonestrom and others, 2007).

Saturated basin fill beneath the Amargosa River near 

Eagle Mountain connects the AFFCR and PDVS groundwater 

basins (fig. 6). Basin fill has limited thickness, is less than 

1-mi wide, and Eagle Mountain is an isolated block of 

carbonate rocks (Sweetkind and others, 2001). Less than 

300 acre-ft/yr of predevelopment flow is estimated to move 

beneath the Amargosa River, assuming a hydraulic gradient 

of 29 ft/mi between wells Eagle Mtn North and 

Hwy 127 MM21-1, a width of 1 mi, and an average 

transmissivity of 1,000 ft2/d.

Saturated basin fill between Stewart Valley and the 

Ash Meadows discharge area connects the PDVS and Ash 

Meadows groundwater basins (fig. 6). Basin fill is less than 1 

mi wide and bounded by low-permeability rocks (Sweetkind 

and others, 2001). Less than 200 acre-ft/yr of predevelopment 

flow is estimated to move from the PDVS groundwater basin, 

assuming a hydraulic gradient of 14 ft/mi between wells BLM 

Stewart Valley Well and GS-1 Well (AD-12), a width of 1 mi, 

and an average transmissivity of 1,000 ft2/d.

Predevelopment Groundwater Flow

Groundwater flow prior to development can be 

characterized by distributions and rates of groundwater 

recharge and discharge, and by the hydraulic conductivities of 

saturated rocks in the study area. Recharge adds water to the 

groundwater system and locally elevates water levels. Water 

levels locally are depressed where groundwater discharges 

from the system. Recharge and discharge areas are controlled 

by topography, where more recharge occurs in highland 

areas, compared to valley floors, and moves downgradient to 

discharge areas. Topography and hydraulic conductivities of 

geologic units control the rate and distribution of recharge and 

discharge. Hydraulic conductivity and recharge control waterlevel altitudes, flow rates, and flow directions in the saturated 

rocks between recharge and discharge areas. Recharge, 

discharge, and hydraulic conductivities are distributed 

spatially throughout the flow system and their distributions 

characterize the four principal groundwater basins in the study 

area (Fenelon and others, 2016).
18 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 06

Amargosa River

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

Death Valley

Eagle

Mtn Bennetts Spring

Manse Spring

Stump Spring

100

2,000–4,000

<300

<200

Chicago Valley

Death Valley playa

Stewart Valley

Oasis

Valley

Furnace 

Creek 

area

Death 

Valley 

playa

Franklin 

Well area

Franklin 

Lake

Ash Meadows 

discharge area

Saratoga 

Spring 

area

Pahrump

Valley

California

Valley

BLM Stewart Valley

Hwy 127 MM21-1 

AD-4

Devils Hole

Eagle Mtn

North 

GS-1 Well (AD-12)

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Spring

Direction of predevelopment 

groundwater flow

Direction and estimated rate 

of interbasin flow, in 

acre-feet per year

<200

Area of groundwater 

discharge by evapotranspiration—Discharge 

area labeled in red

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

Figure 6. Groundwater basins and major discharge areas in the study area, Nevada and California.
Predevelopment Groundwater Flow 19

Discharge Areas

Discharges define groundwater budgets for undeveloped 

groundwater basins because (1) discharge is approximately 

equal to recharge prior to development; and (2) recharge is 

more difficult to quantify than discharge because recharge 

cannot be measured directly (Bredehoeft, 2007). Imbalances 

between discharge and recharge estimates in the Great Basin 

typically are attributed to interbasin flow (Maxey and Eakin, 

1951). 

Spatial distribution of discharge is controlled by 

topography, hydraulic conductivity (transmissivity), and 

geologic features. Discharge typically occurs either at a 

break in slope of the topography or by strong contrasts in 

hydraulic conductivity between geologic units. Bennetts

and Manse Springs in Pahrump Valley were formed by the 

break in slope between the Spring Mountains and valley 

floor, whereas springs in the Ash Meadows discharge area 

(fig. 6) were formed by a normal fault known as the Gravity 

fault (fig. 5). Discharge from Ash Meadows springs occurs 

from transmissive carbonate rocks because clayey basin fill 

downgradient of the Gravity fault limits flow. Locations and 

magnitudes of discrete discharges also are controlled by 

estimated transmissivity distributions. For example, assuming 

two springs discharge from the same aquifer, the part of the 

aquifer contributing 6 ft3/s to one spring must be considerably 

more transmissive than another part of the aquifer contributing 

0.006 ft3/s to another spring. In the study area, each regional 

discharge area is characterized individually because estimated 

hydraulic-property distributions affect local variations in 

discharge rates within each discharge area.

Discharge typically occurs in topographically low 

areas where groundwater is at or near land surface by three 

processes: (1) spring flow and seepage; (2) transpiration by 

local phreatophytic vegetation; and (3) evaporation from soil 

and open water. Each of these processes can be measured 

directly or estimated. As groundwater emerges from springs, 

it forms ponds or flows into free-flowing drainages or local 

reservoirs. Some of this water infiltrates downward into 

soils and possibly into an underlying aquifer, but most of the 

water ultimately is consumed by phreatophytic vegetation 

or is evaporated. The combined processes of evaporation 

and transpiration are referred to as evapotranspiration (ET), 

where only groundwater evapotranspiration is considered in 

this study. Major discharge areas in the study area occur in 

topographic lows of each groundwater basin (fig. 6).

The amount and rate of groundwater lost to the 

atmosphere by ET from discharge areas varies with 

vegetation type and density, soil characteristics, depth to 

water, and climate (Laczniak and others, 1999, 2001; Reiner 

and others, 2002; DeMeo and others, 2003; Moreo and 

others, 2007; Allander and others, 2009). ET rates generally 

increase as vegetation health, vegetation density, and soil 

moisture increase. Previous studies in Nevada have applied 

various remote-sensing techniques using satellite imagery 

in combination with field mapping and ET measurements 

to identify and group areas of similar vegetation and soil 

conditions within discharge areas (Smith and others, 2007; 

Allander and others, 2009; Garcia and others, 2014; Berger 

and others, 2016). Vegetation and soil groupings are referred 

to as ET units because they represent areas with similar ET 

rates. Typical ET units include areas of no vegetation (such 

as open water, dry playa, and moist bare soil) and areas with 

vegetation dominated by phreatophytic shrubs, grasses, rushes, 

and reeds.

Regional discharge is estimated by mapping ET units, 

estimating the total ET from all units, and subtracting nongroundwater contributions such as local precipitation and 

infiltrated floodwaters. Local precipitation and infiltrated 

floodwaters are assumed to evaporate locally, or supply plant 

needs when available (Laczniak and others, 1999). Total 

discharge can be approximated well by estimating ET rates 

at discrete locations and delineating ET areas, as was done 

in the Ash Meadows discharge area (Laczniak and others, 

1999). Total discharge in Ash Meadows and Oasis Valley is 

defined well because groundwater discharge by ET (ETGW) 

from different types of vegetative cover was estimated from 18 

multiyear, micrometeorological measurement sites (Laczniak 

and others, 1999; Reiner and others, 2002).

Predevelopment discharge has been estimated for each 

discharge area in the study area (table 4). Estimates consisted 

of existing values within each discharge area (Maxey and 

Jameson, 1948; Malmberg, 1967; Laczniak and others, 1999, 

2001, 2006; Reiner and others, 2002; DeMeo and others, 

2003; and Fenelon and others, 2016). Estimates from the Ash 

Meadows discharge area (Laczniak and others, 1999), Indian 

Springs (Maxey and Jameson, 1948), and Oasis Valley (Reiner 

and others, 2002) are accurate because of detailed, sitespecific, field studies (fig. 6). Discharges from Chicago Valley, 

California Valley, Franklin Well area, and Shoshone-to-Tecopa 

areas are less certain because ETGW rates were extrapolated 

from ET measurements in Oasis Valley and Ash Meadows 

discharge areas (Laczniak and others, 2001). Discharges 

from Death Valley playa, Franklin Lake, Furnace Creek area, 

Pahrump Valley, and Saratoga Spring area were revised in 

this study because ET rates from playas have been previously 

overestimated, ET areas have been classified incorrectly, or 

discharges have been excluded inadvertently (Belcher, 2004; 

Belcher and Sweetkind, 2010; Belcher and others, 2017).

Discharges primarily differed between DVRFS.v2 

and DV3 projects in areas with playas (table 4). Revised 

discharges were reduced markedly from previous estimates 

because plausible ETGW rates from playas approach 0 ft/yr 

(Jackson and others, 2018). Previously estimated ETGW rates 

on playas in the study area ranged from 0.13 to 0.15 ft/yr 

(DeMeo and others, 2003). These ETGW rates were interpreted 

as annual averages, but better represent the detection limit 

on ETGW rates, given limitations of the Bowen-ratio method 

(Garcia and others, 2014).
20 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 4. Predevelopment discharge by discharge area for previous and current 

regional flow analyses of the study area, Nevada and California.

[Groundwater basin: AFFCR, Alkali Flat–Furnace Creek Ranch; PDVS, Pahrump to Death 

Valley South; PMOV, Pahute Mesa–Oasis Valley. DVRFS.v2: Death Valley Regional Flow 

System version 2 model (previous regional flow analysis). DV3, Death Valley version 3 model 

(current regional flow analysis)]

Groundwater basin Discharge area

Annual discharge

(acre-feet)

DVRFS.v2 DV3

AFFCR Furnace Creek area 1,2 5,700 6,100

Franklin Well area 340 340

Franklin Lake 1 1,000 0–700

Death Valley playa 3,1 1,400 0–100

Ash Meadows Ash Meadows with Amargosa Flat 17,900 18,100

Indian Springs 660 700

PMOV Oasis Valley 6,000 6,200

PDVS Pahrump and Stewart Valleys 4 10,600 13,300

Chicago Valley 430 430

Shoshone area 2,100 2,100

Tecopa/California Valley area 6,200 6,300

Saratoga Spring area 5 2,460 0–400

Death Valley playa 3,1 6,800 0–100

TOTAL 61,600 53,600–54,900

1

 Discharges differ because playas were assigned different groundwater-evapotranspiration rates.

2

 Discharges differ because diversions from Furnace Creek wash were not included in 

DVRFS.v2 project.

3

 Comparison limited to playa area in DV3 study area.

4

 Discharges differ because total discharge from Pahrump Valley in DVRFS.v2 project was 

limited to predevelopment discharges from Bennetts and Manse Springs.

5

 Discharges differ because DVRFS.v2 project used groundwater-evapotranspiration areas 

and rates that were classified incorrectly in DeMeo and others (2003) and did not subtract the 

720 acre-feet per year (acre-ft/yr) (1 cubic foot per second) of return flow from the Amargosa 

River downstream of Dumont Dunes streamgage. The DV3 discharge estimate is a net discharge 

estimated from a water balance done for the Saratoga Spring topographic basin in this study. 

Predevelopment discharge ranges between 800 and 1,200 acre-ft/yr, where subtraction of the 720 

acre-ft/yr of return flow results in a net discharge of less than 400 acre-ft/yr in this study.

Hydraulic-property estimates and predictions of 

groundwater discharges from springs depend greatly on 

specified locations and rates of discharges. Previous studies 

were designed to estimate the total predevelopment discharge 

from discharge areas, but not specifically to identify each 

discrete discharge location within a discharge area (Laczniak 

and others, 1999, 2001, 2006; Reiner and others, 2002; 

DeMeo and others, 2003). Most groundwater either discharges 

discretely from springs or evapotranspires in ET units that are 

downgradient of the springs. Discharge rates differ markedly 

between springs and ET areas. For example, Crystal Pool in 

the Ash Meadows discharge area discharges 6.4 ft3/s (4,600 

acre-ft/yr) from a 5-ft-diameter spring pool (0.0018 acres), 

which equates to a discharge rate of more than 2,500,000 

ft/ yr. This discharge rate is much more intense than ET rates 

of 0.9–8.2 ft/yr from the 3,000 acres of ET units downgradient 

of Crystal Pool (Laczniak and others, 1999).

“Double counting” of discharge occurs when discharges 

from spring orifices feed downgradient spring runs, wetlands, 

and moist soils that support phreatophytic vegetation. 

Predevelopment discharge in a discharge area is double 

counted if spring discharge and ET are summed and the ET 

areas are fed by the springs. Spring orifices and ultimate ET 

locations can differ by more than 3 mi. To prevent double 

counting of discharge, differences in locations and rates of 

discharge were reconciled by delineating the ET area fed by 

each spring and attributing cumulative ETGW in excess of 

the spring discharge to the ET area. ET areas fed by springs 

were delineated by summing ETGW rates from ET units 

downgradient of the springs until cumulative ETGW equaled 

measured spring discharges. Differences in locations and rates 

from diversions, ET areas, and springs were reconciled in Ash 

Meadows, Furnace Creek, Pahrump Valley, Lower Amargosa, 

and Saratoga Spring discharge areas (fig. 6).
Predevelopment Groundwater Flow 21

Ash Meadows

Ash Meadows discharge area includes Amargosa Flat, 

more than 30 springs and seeps at Ash Meadows, and ET 

areas that extend downgradient from Ash Meadows springs 

to Carson Slough (fig. 7). Predevelopment discharge from 

the Ash Meadows discharge area totals 18,100 acre-ft/yr 

(Laczniak and others, 1999). Most of the discharge occurs 

from 19 springs in Ash Meadows, which discharge a total 

of 16,150 acre-ft/yr (Dudley and Larson, 1976; Laczniak 

and others, 1999). Discharge by ETGW from ET units within 

Amargosa Flat accounts for 1,700 acre-ft/yr of the total 

discharge, whereas estimated discharge from ET units 

downgradient of Ash Meadows springs is about 250 acre-ft/yr 

(Laczniak and others, 1999).

Discharge from the Ash Meadows discharge area would 

be twice the predevelopment estimate of 18,100 acre-ft/yr if 

double counting of discharge is not reconciled. Total discharge 

from springs in Ash Meadows (16,150 acre-ft/yr) is similar 

to the 16,400 acre-ft/yr of ETGW (Laczniak and others, 1999) 

estimated from about 10,000 acres of ET units downgradient 

of the springs (fig. 7). Spring discharges and estimated 

ETGW from ET units are functionally equivalent within the 

uncertainty of the measurements (Laczniak and others, 1999). 

Attributing virtually all discharge to springs rather than to 

large areas of seeps implies that all discharge in the Ash 

Meadows discharge area occurs through less than 1 acre of 

spring pools.

Some water that evapotranspires from ET units 

downgradient of Ash Meadows springs is sourced from diffuse 

seepage rather than runoff from spring discharge. Water seeps 

diffusely from the underlying carbonate rocks to the water 

table through overlying clay-rich, basin fill. Diffuse seepage 

of 0.02 ft/yr was estimated from local hydraulic gradients of 

0.2 ft/ft and a hydraulic conductivity of 0.0003 ft/d. Diffuse 

seepage discharges as ETGW from the water table in the Ash 

Meadows discharge area and totals about 250 acre-ft/yr.

Springs in Ash Meadows discharge groundwater from 

underlying carbonate rocks that minimally interact with 

overlying basin fill prior to entering spring pools (fig. 8). 

Flows are controlled by heads decreasing between carbonate 

rocks and spring pools. Water levels in spring pools generally 

are higher than the water table around spring pools, as 

evidenced by the lack of vegetation far from spring pools 

and runs. Vegetation typically occurs in the Ash Meadows 

discharge area where the water table is within 10 ft of land 

surface (Laczniak and others, 1999). Absence of vegetation 

far from spring pools and runs suggests that the water table 

is more than 10 ft below land surface, and thus, lower than 

the pools. Minimal spring discharge returns to the water table 

from spring runs because clay predominates in the basin fill. 

A delta-shaped area of phreatophytes downgradient of Crystal 

Pool is an exception where return flow occurs (fig. 7).

Furnace Creek Area

About 90 percent of predevelopment discharge from 

the AFFCR groundwater basin (fig. 6) exits in the Furnace 

Creek area (table 4), which extends from the alluvial fan of 

Furnace Creek Wash in the southwest to Nevares Springs in 

the northeast (fig. 9). Prior to development in the Furnace 

Creek area, groundwater either discharged from springs 

upgradient of Furnace Creek Wash or moved as subsurface 

flow through Furnace Creek Wash and discharged by ETGW

from phreatophytes on the alluvial fan (fig. 9). Groundwater 

development began with the alteration of springs and 

installation of collection galleries that act as French drains in 

Furnace Creek Wash. Furnace Creek Wash has three collection 

galleries: (1) a sump; (2) buried tile; and (3) the Furnace Creek 

Inn tunnel (fig. 9), which collect and divert groundwater in the 

wash principally for irrigation at The Oasis at Death Valley, 

formerly known as Furnace Creek Ranch. Discharge from 

Travertine and Texas Springs also is collected and diverted for 

water supply in the Furnace Creek area.

Predevelopment discharge from the Furnace Creek area 

totals 8.5 ft3/s (6,200 acre-ft/yr). Nevares, Travertine, Texas, 

and undeveloped springs discharge 2.8 ft3/s (2,000 acre-ft/

yr) and ungaged ETGW near Travertine Springs discharges 

about 0.1 ft3/s (70 acre-ft/yr). A total of 2.0 ft3/s (1,400 acre-ft/

yr) of subsurface flow in Furnace Creek Wash is diverted by 

three collection galleries, whereas the remaining subsurface 

flow passes through the wash and discharges as ETGW on the 

alluvial fan (fig. 9).

Predevelopment discharge from the Furnace Creek area 

was estimated by reevaluating previous water-budget estimates 

and conceptual models. Rates and locations of predevelopment 

discharge differed primarily because of conceptual models 

that either included or excluded collection galleries in Furnace 

Creek Wash. The conceptual model used in this study is based 

on the evaluation of data during three hydrologically distinct 

periods: (1) predevelopment; (2) mining-tourism; and (3) 

restoration.

Previous Predevelopment Estimates And Conceptual 

Models

Previously published water budgets of the Furnace 

Creek area synoptically totaled discharge during two periods: 

1956–63 (Pistrang and Kunkel, 1964; Hunt and others, 1966) 

and 1990–2000 (Belcher and Sweetkind, 2010). Estimates 

of total discharge from the Furnace Creek area ranged from 

5.6 ft3/s (4,100 acre-ft/yr; Hunt and others, 1966) to 7.9 ft3/s 

(5,700 acre-ft/yr; Belcher and Sweetkind, 2010). Estimates of 

total discharge from the Furnace Creek area differed because 

conceptual models differed. Miller (1977) is not included 

because reported discharges were limited to Travertine and 

Texas Springs.
22 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 07

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second National Elevation Data (NED). 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983 (NAD83).

373

373

190

Last Chance

Spring

Big Spring

Fairbanks Spring

Purgatory Spring Well

Jack Rabbit

Spring

Five Springs Area Longstreet Spring

Point of Rocks Spring

Soda Spring

Rogers Spring

Crystal

Pool

Cold Spring

School

Spring Marsh Spring

North and South

Scruggs Springs

Collins Spring

1 Davis Spring

2 Davis Spring

Ash Tree

Spring

King Pool Spring

Devils

Hole Devils Hole

Well (AM-5)

GF-2B deep

(AM-11)

Death Valley 

Junction

Delta-shaped 

area of 

phreatophytes

Franklin

Lake

Amargosa 

Flat

Stewart 

Valley

Resting Spring

Range

Amargosa Desert

Carson Slough

Ash Meadows 

discharge area

ASH MEADOWS

ALKALI FLAT–

FURNACE

CREEK

RANCH PAHRUMP TO 

DEATH VALLEY

SOUTH

Franklin Wells Area

0 4 MILES

0 2

2

4 KILOMETERS

116°30' 116°15'

36°

30'

36°

15'

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Spring

Area of groundwater 

discharge by evapotranspiration

Localized hydraulic barrier 

formed by fault —Location 

and orientation of fault 

from Dudley and Larson 

(1976). Interpretation of 

fault as barrier is based on 

hydraulic evidence.

Map

area

Study 

area

Figure 7. Springs and evapotranspiration areas in the Ash Meadows discharge area and vicinity, Nevada.
Predevelopment Groundwater Flow 23

sac19-4233_fig 08

Devils Hole

Ash Meadows discharge area

Spring

Gravity

fault

SOUTHWESTNORTHEAST

Diagram not to scale, vertical dimension greatly exaggerated.

EXPLANATION

Basin fill—Gravel, sand and mud; silt and clay west of gravity 

fault

Carbonate rock

Spring-flow zone—Upward flow zone developed along and 

contemporary with growth faults

Fault—Arrow indicates direction of relative fault movement. 

Solid where fault forms barrier to lateral flow from 

carbonate rock. Dashed where fault forms conduit for 

upward flow in basin fill

Water table

Potentiometric surface in carbonate rock

Area of evapotranspiration—Height of vegetation indicates 

relative quantity of transpiration. Length of arrow 

indicates relative quantity of evaporation

General direction of groundwater flow—Size of arrow 

indicates relative magnitude of groundwater flow

Figure 8. Groundwater flow to springs and phreatophyte areas in the Ash Meadows discharge area, Nevada. Figure modified 

from Laczniak and others (1999).
24 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 09

Furnace Creek Wash

Black 

Mountains

Furnace 

Creek 

Ranch

Funeral Mountains

Death Valley Playa

Death Valley Playa

Alluvial Fan

Travertine Springs

Texas Springs

Nevares Springs

Furnace Creek 

Inn tunnel

Furnace Creek 

Wash sump

Furnace Creek 

Wash buried tile

TxCmpMW-1

LFCW-01

WRPMW-6

WRPMW-3

UFCW-02

FCWSPW-01

FCWSPW-03

FCWSPW-02

EXPLANATION

Observation well

Pumping well

Diversion

Spring complex

Direction of predevelopment 

groundwater flow

Area of groundwater 

discharge by evapotranspiration—Modified from 

DeMeo and others (2003)

Phreatophytes fed by 

subsurface flow from 

Furnace Creek Wash

Phreatophytes fed by return 

flow from Furnace Creek 

Ranch

Surface geologic unit

Basin fill

Volcanic-sedimentary rocks

Carbonate rocks

Map

area

Study 

area

0 1 MILE

0 10

10

1 KILOMETER

Image copyright from Esri, 2018: ESRI_Imagery_World_2D. Base from U.S. Geological Survey digital data, 

1:100,000. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°54' 116°52' 116°50' 116°48'

36°

30'

36°

28'

36°

26'

Figure 9. Discharge locations and the historical water-collection system in the Furnace Creek area, California.
Predevelopment Groundwater Flow 25

Predevelopment-discharge estimates from the Furnace 

Creek area during 1956–63 (Pistrang and Kunkel, 1964; Hunt 

and others, 1966) were similar (table 5) and assumed that 

all discharge occurred in Furnace Creek Wash upgradient 

of Furnace Creek Inn tunnel (fig. 9). Water collected by 

a sump, buried tile, and the Furnace Creek Inn tunnel for 

irrigation at Furnace Creek Ranch (fig. 9) were included 

as part of the predevelopment discharge because collected 

groundwater would have passed through the wash prior to 

development. Discharge by ETGW on the alluvial fan was 

not included because this discharge was assumed to be 

reinfiltrated spring discharge and return flow from irrigation 

at Furnace Creek Ranch, which was sourced from diverted 

groundwater in Furnace Creek Wash (Hunt and others, 1966, 

p. B37). Discharge from Nevares Springs during 1956–63 

differed by 0.1 ft3/s (70 acre-ft/yr; table 5) because small 

springs downgradient of Nevares Springs were interpreted as 

reinfiltrated spring discharge and not included by Pistrang and 

Kunkel (1964, p. Y19), whereas all discharges were totaled 

by Hunt and others (1966, p. B35). The low permeability of 

the underlying mudstones, classified as volcanic-sedimentary 

rocks in figure 9, downgradient of carbonate rocks supports 

the interpretation of Pistrang and Kunkel (1964).

Predevelopment conditions were approximated during 

the 1990–2000 period (Belcher and Sweetkind, 2010) by 

summing discharges from Travertine, Texas, and Nevares

Springs, and ETGW areas on the alluvial fan (table 5). 

Average discharges from Travertine and Texas Springs were 

estimated from measurements during the periods 1956–72 

and 1989–96, respectively (Belcher and Sweetkind, 2010, 

table C-2). Discharge from Nevares Springs was the sum 

of average discharge from the main spring area during the 

period 1956–57 and discharges from other nearby springs. 

Belcher and Sweetkind (2010) did not include discharge 

from the collection galleries in Furnace Creek Wash because 

predevelopment conditions were being simulated (Belcher 

and Sweetkind, 2010). The conceptual model used by Belcher 

and Sweetkind (2010) assumes that 4.7 ft3/s (3,400 acre-ft/yr) 

bypasses Travertine and Texas Springs, moves downgradient, 

and enters the head of the alluvial fan.

Differences in conceptual models of the natural system 

understandably arise because all discharges were measured 

60 or more years after the Furnace Creek area was developed 

and total predevelopment discharges differed little in previous 

investigations. Travertine and Texas Springs were diverted 

to collection galleries in Furnace Creek Wash between 1880, 

when mining commenced, and 1920 when tourism was 

introduced (Greene and Latschar, 1981). A single discharge 

measurement was reported for Texas Springs and the sump 

during 1941, but frequent, repeatable measurements of 

discharge from springs and collection galleries in the Furnace 

Creek area were not reported until 1956 (Pistrang and Kunkel, 

1964). ETGW areas on the alluvial fan were not estimated 

systematically until more than 100 years after the Furnace 

Creek area was developed (DeMeo and others, 2003).

DV3 Conceptual Model—Three Hydrologically Distinct 

Periods

Predevelopment, mining-tourism, and restoration are 

three hydrologically distinct periods in the Furnace Creek 

area that occurred prior to 1880, and during 1880–2008 

and 2009–18, respectively. Groundwater flow prior to 

development was inferred to total 8.6 ft3/s (6,200 acre-ft/yr)—

where Nevares, Travertine, Texas, and undeveloped springs 

discharged 2.9 ft3/s (2,100 acre-ft/yr), and the remaining 5.6 

ft3/s (4,100 acre-ft/yr) flowed through Furnace Creek Wash 

to the alluvial fan (table 5). Development during the miningtourism period diverted a total of 4.1 ft3/s (3,000 acre-ft/yr) 

from springs and collection galleries in Furnace Creek Wash. 

Diversions from Travertine and Texas Springs redirected 2.1 

ft3/s (1,500 acre-ft/ yr) from flowing down washes and across 

the alluvial fan. Collection galleries in Furnace Creek Wash 

diverted 2.0 ft3/s (1,400 acre-ft/yr) of subsurface flow that 

would have entered the alluvial fan; therefore, discharge from 

the alluvial fan was reduced from 5.6 to 3.6 ft3/s (table 5). 

Most of the diverted water was applied at Furnace Creek 

Ranch for irrigation of date palms and a golf course, and to 

support tourism. Flow through the Furnace Creek area was 

altered during the restoration period by (1) restoring 1.7 ft3/s 

(1,200 acre-ft/yr) to spring runs downgradient of Travertine

and Texas Springs; (2) pumping 0.4 ft3/s (300 acre-ft/yr) 

from water-supply wells FCWSPW-01, FCWSPW-02, and 

FCWSPW-03 north of Travertine Springs; and (3) collecting 

non-potable groundwater from collection galleries in Furnace 

Creek Wash (fig. 9).

Changing discharge from any location affects all other 

discharges in the Furnace Creek area, as shown by pumping. 

Supply wells FCWSPW-01, FCWSPW-02, and FCWSPW-03 

began pumping in March 2009 and averaged 0.4 ft3/s (300 

acre-ft/yr) during 3 years of pumping (fig. 10). Combined 

discharge from Travertine and Texas Springs decreased by 0.3 

ft3

/s (200 acre-ft/yr) during the first 2 years of pumping before 

a local equilibrium was established (Jackson and Halford, 

2020). The additional 0.1 ft3/s (100 acre-ft/yr) of pumped 

water that did not come from spring capture was supplied from 

storage in the basin fill.

Discharge from Springs

Discharges from Travertine, Texas, and undeveloped 

springs are assumed to minimally infiltrate Furnace Creek 

Wash and the alluvial fan, and do not contribute to discharge 

by ETGW from phreatophytes on the alluvial fan. This was true 

during the mining-tourism period because all spring discharges 

were collected and applied to Furnace Creek Ranch. During 

the restoration period, this assumption is supported by 

discharge from Travertine Springs flowing across the alluvial 

fan. A sufficient fraction of the 1.3 ft3

/s (940 acre-ft/yr) from 

the restored Travertine Springs flows across the alluvial fan to 

form ponds and wetlands on the floor of Death Valley (Richard 

Friese, National Park Service, oral commun., 2015).
26 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 5. Predevelopment and post-development discharge estimates for all sites in the Furnace Creek area, California, prior to

1880 to 2018.

[“–” indicates that the site existed and was measured, but measurements were not included based on the conceptual model. No data indicates that the site existed 

but was not measured during the period of study. Abbreviations: acre-ft/yr, acre-feet per year; ft3/s, cubic feet per second; N/A, not applicable]

Measurement site

Discharge (cubic feet per second)

Sub Area

1956–63 1956–63 1990–2000 Prior to 1880 1880–2008 2009–18

Pistrang 

and Kunkel 

(1964)

Hunt and 

others 

(1966)

Belcher and 

Sweetkind 

(2010)

This study This study This study

Predevelopment Predevelopment Predevelopment Predevelopment Miningtourism Restoration

Travertine Springs 1.9 1.9 1.9 1.9 1.7 1.3

Furnace Creek 

Wash

Texas Springs 0.5 0.5 0.5 1 0.3 0.4 0.4

Undeveloped springs 0.1 0.1 – 0.1 0.1 0.1

Ungaged ET near Travertine Springs 0.5 – – 0.1 0.1 0.1

Sump 1.3 1.3 – – 1.3 1.3

Buried tile 0.4 0.4 – – 0.4 0.4

Furnace Creek Inn tunnel 0.3 0.5 – – 0.3 0.3

Trench – destroyed in 1959 – 0.2 – – – –

Phreatophytes on alluvial fan No data No data 4.7 5.6 3.6 3.6 Alluvial fan

Nevares Springs 0.6 0.7 0.8 0.6 0.6 0.6 Carbonate 

rocks

Pumping N/A N/A N/A N/A N/A 0.4

Total discharge—ft3

/s 5.6 5.6 7.9 8.6 8.5 8.5

—acre-ft/yr 4,100 4,100 5,700 6,200 6,200 6,200

1

 Discharge measured in 1926 prior to construction of tunnel at Texas Spring.

Discharge from Phreatophytes on Alluvial Fan

ETGW on the alluvial fan downgradient of Furnace 

Creek Ranch is sustained in part by return flow. Irrigation 

and water features at Furnace Creek Ranch are supplied 

by diversions from Travertine Springs, Texas Springs, and 

collection galleries in Furnace Creek Wash that total 4.1 

ft3/s (3,000 acre-ft/yr). Some of the diverted water becomes 

return flow and infiltrates the alluvial fan to the westnorthwest of Furnace Creek Ranch (fig. 9). All discharge 

from phreatophytes to the west-northwest of Furnace Creek 

Ranch totals about 1 ft3/s (720 acre-ft/yr). 

In this study, predevelopment discharge from 

phreatophytes on the alluvial fan totaled 5.6 ft3/s (4,100 

acre-ft/yr; table 5), which accounts for return flow and other 

factors. DeMeo and others (2003) reported a discharge of 

4.7 ft3/s (3,400 acre-ft/yr) from the alluvial fan, which was 

used in the DVRFS.v2 project (Belcher and Sweetkind, 

2010; table 5). The 4.7 ft3/s (3,400 acre-ft/yr) was revised 

by adding the 2.0 ft3/s (1,400 acre-ft/yr) of diverted water 

from collection galleries in Furnace Creek Wash, and then 

subtracting discharge from the Death Valley playa (0.1 ft3/s; 

70 acre-ft/yr) and return flow (1 ft3/s; 720 acre-ft/yr).

A predevelopment-discharge estimate of 5.6 ft3/s (4,100 

acre-ft/yr) from the alluvial fan assumes that all discharge 

from phreatophytes to the west-northwest of Furnace Creek 

Ranch (1 ft3/s; 720 acre-ft/yr) is entirely attributed to return 

flow. More likely only a fraction of the water diverted for 

Furnace Creek Ranch becomes return flow. About 1 ft3/s 

of discharge from the alluvial fan occurs downgradient 

of Furnace Creek Ranch. Therefore, subsurface flow 

through Furnace Creek Wash during predevelopment could 

range from 5.6 to 6.6 ft3/s (4,100 to 4,800 acre-ft/yr), and 

subsurface flow through Furnace Creek Wash during the 

mining-tourism period could range from 3.6 to 4.6 ft3/s 

(2,600 to 3,300 acre-ft/yr).

Furnace Creek Wash—A Transmissive Feature

Permeable sediments in Furnace Creek Wash connect 

basin-fill deposits upgradient of Travertine Springs to the 

alluvial fan on the floor of Death Valley (fig. 9). Furnace 

Creek Wash consists of coarse-grained sediments as 

evidenced by lithologic well logs from wells LFCW-01

and UFCW-02, which are open to gravels and sands in 

Furnace Creek Wash. Rocks surrounding Furnace Creek 

Wash are predominantly low-permeability mudstones, 

as evidenced by a low hydraulic conductivity of 0.0001 

ft/d in well TxCmpMW-1 (Jackson and Halford, 2020). 

Low-permeability mudstones surrounding Furnace Creek 

Wash and the radial shape of the alluvial fan indicate that 

most, if not all, groundwater enters the alluvial fan from 

the mouth of Furnace Creek Wash. The conceptual model 

depends greatly on 5.6 ft3/s (4,100 acre-ft/yr) passing 

through Furnace Creek Wash as subsurface flow, which 

requires an average transmissivity of 40,000 ft2/d. This 

assumes a channel width of 300 ft and hydraulic gradient 

of 0.04 ft/ft.
Predevelopment Groundwater Flow 27

sac19-4322_fig 10 Discharge, in cubic feet per second 

156

158

160

162

164

166

2008 2009 2010 2011 2012

Year

Pumping from supply wells

0

1

417

419

431

433

305

307

309

Water-level altitude above National Geodetic Vertical Datum of 1929, in feet

Well WRPMW-6, 1.3 miles upstream of collection galleries

0.3 miles from supply wells

1.8 miles from supply wells

Well LFCW-01, 0.3 miles downstream of collection galleries

0.5 miles from supply wells

Well WRPMW-3, 1.0 miles upstream of collection galleries

1.0 miles from supply wells

Well UFCW-02, 0.5 miles upstream of collection galleries

Figure 10. Groundwater-level fluctuations in the Furnace Creek area from collection galleries 

in Furnace Creek Wash and water-supply wells, California, 2008–12.
28 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Conveying 5.6 ft3/s (4,100 acre-ft/yr) requires that 

Furnace Creek Wash between Travertine Springs and the 

Furnace Creek Inn tunnel be very transmissive. Annual 

fluctuations of 8 ft in well LFCW-01 are consistent with 

Furnace Creek Wash being very transmissive (fig. 10). This is 

because seasonal water-level changes are attenuated minimally 

between the well and the sump and tile collectors that are 0.3-

mi upgradient. Seasonal fluctuations were observed upgradient 

of the sump and tile collectors in well UFCW-02 prior to 

pumping of the supply wells (fig. 10). Seasonal fluctuations 

were attenuated in wells WRPMW-3 and WRPMW-6 by 

less transmissive coarse-grained sediments upgradient of 

Travertine Springs.

Mining-Tourism Period—A Steady-State Condition

Discharge estimates during the mining-tourism period 

(1880–2008; table 5) best represent steady-state conditions 

for this investigation. Total predevelopment discharge from 

phreatophytes on the alluvial fan is uncertain because no 

information is available regarding the density of phreatophytes 

prior to development. Collection galleries in Furnace Creek 

Wash behave as French drains that divert a steady source 

of groundwater moving through the wash, resulting in little 

change in groundwater storage but the capture of discharge 

from phreatophytes on the alluvial fan. Phreatophyte density 

and ETGW rates decreased with time in response to capture, but 

steady-state conditions likely were established by the end of 

the 128-year mining-tourism period.

Use of the predevelopment (prior to 1880) period for 

steady-state model calibration also is infeasible because 

of limited data. The mining-tourism period has concurrent 

measurements of discharges and water levels, unlike the 

predevelopment period. Earliest groundwater levels were 

measured during 1958 (Pistrang and Kunkel, 1964) or about 

80 years after the hydrology of the Furnace Creek area was 

modified for mining (Greene and Latschar, 1981). Most wells 

in the Furnace Creek area were drilled after 2000. Discharges 

from Nevares, Travertine, Texas, and undeveloped springs 

and ETGW on the alluvial fan were measured or estimated 

concurrently and totaled 6.4 ft3/s (4,600 acre-ft/yr). Water 

diverted by collection galleries in Furnace Creek Wash was 

measured during 1956 and 1963 (Pistrang and Kunkel, 1964). 

Total diversions of 2.0 ft3/s (1,400 acre-ft/yr) were assumed to 

be unchanged between 1960 and 2018.

Pahrump Valley

The Pahrump Valley discharge area includes Bennetts, 

Manse, and Stump Springs, and ETGW areas in Pahrump and 

Stewart Valleys (fig. 11). Predevelopment discharge from 

the Pahrump Valley discharge area totaled 13,300 acre-ft/yr. 

Bennetts and Manse Springs discharged 9,800 acre-ft/yr (13.5 

ft3/s) prior to development in 1910 and accounted for more 

than 70 percent of predevelopment discharge. Most discharge 

from Bennetts and Manse Springs reinfiltrated the shallow 

basin fill and was consumed by downgradient phreatophytes 

in central Pahrump Valley (Malmberg, 1967). Phreatophytes 

in northern Pahrump, southern Pahrump, and Stewart Valleys 

were sustained directly from shallow groundwater, not spring 

runs (Harrill, 1986). Discharge from these areas, which were 

not dependent on Bennetts and Manse Springs, totaled 3,500 

acre-ft/yr (fig. 11).

Predevelopment discharges from Pahrump and Stewart 

Valleys for this investigation were revised by evaluating 

groundwater budgets from previous investigations. Quantities 

and distributions of discharge from Harrill (1986) were 

accepted as reported, with a few exceptions. Discharges 

from Bennetts and Manse Springs totaled 9,800 acre-ft/yr 

(13.5 ft3/s), but issued from spring orifices rather than being 

distributed downgradient across phreatophyte areas as was 

simulated by Harrill (1986). Remote sensing estimates of 

discharge from Stewart Valley, which totaled 1,000 acre-ft/ yr 

(Laczniak and others, 2001), replaced estimates from Harrill 

(1986). Revised discharge estimates for Stump Spring 

(Jackson and Halford, 2020) and inclusion of phreatophytes 

1–8 mi south of Manse Spring (Malmberg, 1967), which were 

inadvertently excluded by Harrill (1986) (fig. 11), added 300 

acre-ft/yr to previous estimates by Harrill (1986). Mapped 

discharge areas (and predevelopment-discharge rates) from the 

previous investigations that are used in this project are shown 

in figure 11.

Discharge prior to development in Pahrump Valley 

was underestimated by Malmberg (1967). Evapotranspired 

discharge and extent of phreatophytes downgradient of 

Bennetts and Manse Springs in 1961 were assumed by 

Malmberg (1967) to be similar to predevelopment conditions. 

ETGW from these phreatophytes totaled 7,000 acre-ft/yr (9.7 

ft3/s) in 1961 and originated as return flow from irrigation and 

Manse Spring (Malmberg, 1967, p. 28–29). The assumption 

of similar ETGW rates and phreatophyte extents prior to 

development and during 1961 is inconsistent with intensive 

groundwater development in Pahrump Valley. Between 

1916 and 1961, pumping increased from 4,300 to 28,500 

acre-ft/yr and spring discharges decreased from 9,800 to 

1,500 acre-ft/ yr (2.1 ft3/s; Malmberg, 1967, p. 31). ETGW

by phreatophytes from shallow groundwater in northern 

Pahrump, southern Pahrump, and Stewart Valleys totaled 

3,300 acre-ft/yr (Malmberg, 1967, p. 29) and has differed little 

in subsequent estimates (Harrill, 1986; Laczniak and others, 

2001) because these phreatophyte areas are farther from 

pumping than phreatophytes downgradient of Bennetts and 

Manse Springs.
Predevelopment Groundwater Flow 29

sac19-4233_fig 11

Pahrump 

Valley

Spring Mountains

Stewart 

Valley

Chicago 

Valley

Nopah Range

Bennetts Spring

Manse Spring

Stump Spring

EXPLANATION

Spring

Area of groundwater 

discharge by evapotranspiration that is used in 

this study: 

Mapped discharge from 

Malmberg (1967)

Mapped discharge from 

Harrill (1986)

Mapped discharge from 

Harrill (1986) attributed to 

spring run from Bennetts 

Spring

Mapped discharge from 

Harrill (1986) attributed to 

spring run from Manse 

Spring

Mapped discharge from 

Laczniak and others (2001)

Map

area

Study 

area

0 4 MILES

0 2

2

4 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°10' 116°0' 115°50'

36°

10'

36°

Figure 11. Discharge areas in Pahrump and Stewart Valleys, Nevada and California.
30 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Predevelopment discharge of 9,800 acre-ft/yr (13.5 ft3/s) 

from Bennetts and Manse Springs is accurate (Harrill, 1986). 

This discharge combined reported discharges of 7.5 and 6 

ft3/s from Bennetts and Manse Springs, respectively, during 

1875 and 1877 (Maxey and Jameson, 1948, p. 10). These 

measurements were corroborated by measured discharges 

during 1916 from springs and flowing wells that were drilled 

between 1910 and 1916 (Waring, 1921). Discharge from 

Bennetts and Manse Springs totaled 5,800 acre-ft/yr (8.0 

ft3/s), whereas discharge from 8 of 13 flowing wells totaled 

2,600 acre-ft/yr (3.6 ft3/s) during 1916 (Waring, 1921, p. 

64). Discharge from springs and flowing wells exceeded 

8,400 acre-ft/yr (11.6 ft3/s) and would equal measured 

predevelopment discharge from Bennetts and Manse Springs if 

flow from each of the five unmeasured wells equaled average 

discharge of the eight measured wells.

Predevelopment discharges from Pahrump Valley in the 

DVRFS.v2 project differed from those reported by Malmberg 

(1967) and Harrill (1986) and totaled 10,600 acre-ft/yr 

(table 4). Predevelopment discharge from Bennetts and Manse

Springs totaled 9,600 acre-ft/yr (Belcher and Sweetkind, 

2010; 32,400 m3/d in table C-2). The 200 acre-ft/yr (0.3 ft3/s) 

difference between Belcher and Sweetkind (2010) and Harrill 

(1986) likely resulted from rounding as discharge units were 

converted from cubic feet per second to cubic meters per day. 

All discharge from Pahrump Valley was simulated diffusely 

as ETGW from phreatophyte areas with the DVRFS.v2 model, 

including Bennetts and Manse Springs.

Lower Amargosa Area

Lower Amargosa discharge area includes springs and 

ET areas between Shoshone, California, and Dumont Dunes, 

and in Chicago and California Valleys (fig.12). The discharge 

area is divided into three subareas: (1) Chicago Valley; (2) 

Shoshone area; and (3) Tecopa/California Valley area. The 

Shoshone area spans the Amargosa River from the Shoshone 

Spring complex to north of Borehole Spring and extends east 

to include Chappo Spring. The Tecopa/California Valley area 

spans the Amargosa River from Borehole Spring to Dumont 

Dunes and extends east to include springs and ET areas in 

California Valley, China Ranch Wash, and at the southern part 

of the Resting Spring Range.

Predevelopment discharge from the Lower Amargosa 

discharge area totaled 8,830 acre-ft/yr. Discharge from 

Twelvemile Spring and ETGW areas within Chicago 

Valley accounted for 430 acre-ft/yr of the total discharge. 

Predevelopment discharge from the Shoshone area and 

Tecopa/California Valley area totaled 2,100 and 6,300 

acre-ft/ yr, respectively.

Predevelopment discharge from the Lower Amargosa 

discharge area was estimated with remote sensing and 

extrapolated ETGW rates (Laczniak and others, 2001). Reported 

predevelopment discharges have differed by less than 100 

acre-ft/yr between previous investigations (Laczniak and 

others, 2001, p. 36; Belcher and Sweetkind, 2010, p. 103). 

These minor differences can be attributed to rounding and not 

simulating small discharges in model cells on the periphery 

of the Lower Amargosa discharge area (Faunt, Blainey, and 

others, 2010, p. 269).

Shoshone and Tecopa/California Valley areas are 

the functional terminus of discharge within the PDVS 

groundwater basin (fig. 1) because the Greenwater Range and 

Ibex Hills west of the Amargosa River and Sperry Hills south 

of Tecopa are mostly impermeable (fig. 12). Low-permeability 

quartzite and Miocene sedimentary, volcanic, and intrusive 

rocks are present beneath the water table from the Amargosa 

River to the ridges of the Greenwater Range and Ibex Hills 

(Sweetkind and others, 2001, plate 3). Sperry Hills consist of 

low-permeability siliciclastic and Miocene rocks (Sweetkind 

and others, 2001, plate 3). Miocene rocks are correlated with 

mudstones of the Furnace Creek area that have a hydraulic 

conductivity of 0.0001 ft/d in well TxCmpMW-1 (fig. 9). All 

these geologic units have expected transmissivities of less than 

10 ft2/d.

The extent of the ancestral Lake Tecopa also is consistent 

with the area west of the Amargosa River and south of Tecopa 

being relatively impermeable. Lake Tecopa occupied Tecopa 

Valley, reached a maximum depth of 500 ft, and was drained 

186,000 years ago after the Amargosa River breached the 

Sperry Hills (Morrison, 1999). Downgradient features such 

as Dublin Hills and Sperry Hills cannot be transmissive and 

sustain a 500-ft-deep lake.

The terminus of regionally transmissive units south of 

Tecopa was delineated using synoptic discharge measurements 

at temporary streamgage sites (seepage run) in the Amargosa 

River on February 27, 2014 (Belcher and others, 2019). When 

storm-runoff gains are minimal, streamflow gains between 

synoptic measurements identify reaches where groundwater 

flow into the river exceeds evaporative losses. These 

conditions existed because ETGW is less in winter and the 

last runoff event in the Amargosa River at Tecopa, California 

(USGS streamgage 10251300) occurred 60 days prior to the 

seepage run.

Flow in the Amargosa River increased by 3.5 ft3/s 

(2,500 acre-ft/yr) between Borehole Spring (USGS 

streamgage 10251290) and site AR11 (USGS streamgage 

354903116130401), a 5.5-mi reach (fig. 13). Increases from 

areas 3–5.5 mi downstream of Borehole Spring came from 

springs discharging from conglomerates, sandstones, and 

localized megabreccia (China Ranch beds) at the contact with 

underlying siliciclastic rocks on the east side of the Amargosa 

River canyon (Belcher and others, 2019). This contact occurs 

from 50 to 100 ft above the channel of the Amargosa River.
Predevelopment Groundwater Flow 31

sac19-4233_fig 12

Shoshone

Tecopa

California Valley

Resting Spring Range

Nopah Range

Dumont Dunes

Sperry Hills

Pahrump Valley

Greenwater Range

Ibex Hills

Greenwater Valley

Death Valley

Saddle Peak 

Hills

Dublin Hills

Chicago 

Valley

Start of gaining reach

AR11 (end of gaining reach)

Shallow geology changed in 

hydrogeologic framework from 

impermeable rocks to carbonate 

rocks and basin fill

Amargosa River

China Ranch Wash

Twelvemile Spring

Chappo Spring

Tule Spring

Resting Spring

Shoshone Spring 

complex

Borax Spring

Tecopa Hot Springs

West Willow 

Spring

Springs East of 

Tecopa Hills

Borehole Spring

East Willow Spring

AR31

EXPLANATION

Spring

AR31 Streamgage

Area of groundwater 

discharge by evapotranspiration [from Harrill 

(1986) and Laczniak and 

others (2001)]

Phreatophytes fed by 

groundwater discharge

Phreatophytes fed by spring 

runs

Extent of Lake Tecopa Beds

[from Starkey and 

Blackmon (1979)]

0 5 MILES

0 5 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°15' 116°

36°

35°

45'

Study 

area

Map

area

Figure 12. Discharge areas in the Lower Amargosa discharge area and extent of Pleistocene Lake Tecopa, Nevada and 

California.
32 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4322_fig 13

0

2

4

6

0

5

10

0 5 10 15

Cumulative discharge, in thousands

of acre-feet per year

Cumulative discharge, in cubic feet per second

Distance downstream of Borehole Spring, in miles 

Start of gaining reach,

Borehole Spring

(USGS streamgage 

10251290)

End of gaining reach,

 AR11 (USGS streamgage 354903116130401)

AR31 

(USGS streamgage 

354159116144901)

Average Annual 

Groundwater 

Discharge

Evapotranspiration during late February

Measured discharge

Figure 13. Groundwater discharge to river and estimated evapotranspiration in the 

Amargosa River downstream of Borehole Spring, California, on February 27, 2014, and 

cumulative annual evapotranspiration.

Site AR11 (USGS streamgage 354903116130401) 

marked the terminus of the groundwater system because 

streamflow decreased downstream of site AR11 (fig. 13), 

indicating no additional groundwater gains. Flow in the 

Amargosa River decreased by about 1 ft3/s (720 acre-ft/yr) 

between sites AR11 (USGS streamgage 354903116130401) 

and AR31 (USGS streamgage 354159116144901) near 

Dumont Dunes (fig. 12). Observed conditions were consistent 

with relatively large evaporative losses during late February 

and negligible groundwater/surface-water interaction.

Not all groundwater flow into the Amargosa River 

downstream of Borehole Spring was measured because 

substantial ETGW occurred during the seepage run (fig. 13). 

Maximum daily temperatures in Shoshone range from 60 to 

81°F during late February (National Climatic Data Center, 

2017). ETGW rates during late February average 60 percent of 

annual average ETGW rates (Laczniak and others, 1999, 2001). 

Estimated ETGW along the Amargosa River on February 27, 

2014, was computed by multiplying average winter ETGW rates 

by the acreage of ET units for each ET unit, and summing 

total ETGW between streamflow measurement sites. Similarly, 

annual average discharge along the Amargosa River was 

computed using annual average ETGW rates. ETGW totaled 

3,000 acre-ft/yr (4.2 ft3/s) during the seepage run because 

ETGW rates during late February averaged 1.16 ft/yr across 

2,600 acres of ET units.

Annual average discharge and total discharge agree in 

magnitude and distribution on February 27, 2014 during the 

seepage run (fig. 13). Total discharge from the Amargosa River 

downstream of Borehole Spring averages 4,900 acre-ft/yr or 

6.8 ft3/s (Laczniak and others, 2001). Discharge (streamflow) 

in the Amargosa River and ETGW during late February totaled 

7.0 ft3/s (5,100 acre-ft/yr) at site AR11 (USGS streamgage 

354903116130401). Combined discharge and ETGW varied 

little between sites AR11 and AR31 (fig. 13). These results 

partially validate estimates from Laczniak and others (2001) 

and are consistent with site AR11 being the terminus of the 

groundwater system.

ETGW areas sourced from upgradient springs were not 

simulated in this investigation to prohibit double counting 

of discharge. ETGW areas in the Amargosa River canyon 

downstream of site AR11 had discharges totaling 1,100 

acre-ft/yr (1.5 ft3/s), which were attributed to springs 

discharging from the China Ranch beds upstream of site AR11 

(fig. 12). Discharges in ETGW areas downgradient of springs 

in China Ranch Wash similarly was totaled and attributed to 

upgradient springs. Discharges from West Willow and East 

Willow Springs totaled 300 and 200 acre-ft/yr (0.4 and 0.3 

ft3/s), respectively.

Saratoga Spring Area

Groundwater in the Saratoga Spring area is supplied by 

a small topographic basin that mostly is isolated within the 

PDVS groundwater basin (fig. 14). Recharge to the Saratoga 

Spring area is derived from infiltration of streamflow from 

the Amargosa River, local recharge, and subsurface bedrock 

leakage to basin fill. Discharge from the Saratoga Spring area 

occurs from one spring and about 1,450 acres of phreatophytic 

vegetation.
Predevelopment Groundwater Flow 33

sac19-4233_fig 14

Pahrump to Death Valley South groundwater basin boundary

Amargosa River

Sperry Hills

Dumont Sand Dunes

Ibex Hills

Death Valley

Death Valley

Saddle 

Peak

Hills

Ibex Dunes

Salt Spring Hills

Silurian Valley

Black Mountains

Ibex Hills

Owlshead Mountains

Avawatz Mountains

Greenwater 

Valley

Saratoga Springs topographic basin

Saratoga Pools

Borax Spring

West

Willow 

Spring

Springs East of 

Tecopa Hills

Borehole Spring

Tecopa streamgage 

(USGS 10251300)

Dumont Dunes 

streamgage 

(USGS 10251375)

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°15'

35°

50'

35°

30'

35°

40'

116°45'

0 8 MILES

0 8 KILOMETERS

2

2

4

4

6

6

Spring

Streamgage

EXPLANATION

Area of groundwater 

discharge by evapotranspiration [from Harrill 

(1986) and Laczniak and 

others (2001)]

Phreatophytes fed by 

groundwater discharge

Phreatophytes fed by spring 

runs

Amargosa Wild and Scenic 

River

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Map

area

Study 

area

Figure 14. Upgradient source and discharge areas for the Saratoga Spring area, California.
34 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Saratoga Spring topographic basin principally is 

recharged by infiltration from the Amargosa River downstream 

of the Dumont Dunes streamgage (fig. 14). In the period 

of record (1999–2001) at Dumont Dunes streamgage 

(USGS 10251375), base flow in the Amargosa River averaged 

720 acre-ft/yr (1.0 ft3/s). This base flow is assumed to 

infiltrate basin-fill deposits in the river channel, assuming 

minimal evaporative losses, prior to entering Saratoga Spring 

topographic basin as subsurface flow.

Recharge to Saratoga Spring topographic basin also 

occurs from flood events. During flood events, part of the 

streamflow that enters Saratoga Spring topographic basin 

infiltrates the Amargosa River channel (fig. 14). Average 

streamflow during flood events is needed to estimate floodevent recharge to Saratoga Spring topographic basin. Dumont 

Dunes streamgage (USGS 10251375) has an insufficient 

period of record (2 years) to estimate average streamflow 

during flood events. The nearest streamgage with long-term 

streamflow measurements occurs at Tecopa, California 

(USGS streamgage 10251300), where streamflow during 

flood events averaged 1,100 acre-ft/yr (1.5 ft3/s) from 1961 

to 2017. This average was computed from daily streamflows 

that exceed base flow but are less than 100,000 acre-ft/yr 

(138 ft3/s). Infrequent, extreme flood events with streamflows 

of more than 100,000 acre-ft/yr likely do not infiltrate 

the Amargosa River channel. Instead, this runoff flows 

downstream of Saratoga Springs topographic basin and floods 

the Death Valley floor with large volumes of water during 

extreme events (DeMeo and others, 2003). Recharge to 

Saratoga Spring topographic basin during flood events would 

average about 220 acre-ft/yr (0.3 ft3/s) if infiltration rates, 

computed as a percentage of streamflow, in the Amargosa 

River channel are similar to measured infiltration in Fortymile 

Wash (Savard, 1998).

Additional sources of water to the Saratoga Spring 

area are local recharge and subsurface bedrock leakage to 

basin fill. The Saratoga Spring topographic basin is 220,000 

acres in size. The annual precipitation volume totals 23,000 

acre-ft for precipitation rates that exceed 0.4 ft/yr from 

the 1981–2010 Precipitation-elevation Regressions on 

Independent slopes Model (PRISM) precipitation distribution 

(PRISM Climate Group, 2012). A local Maxey-Eakin relation 

estimates recharge as 0.9 percent of annual precipitation 

volume in excess of 0.4 ft/yr (Fenelon and others, 2016) or 

200 acre-ft. Subsurface bedrock leakage from surrounding 

low-permeability rocks to basin fill is less than 50 acre-ft/yr 

assuming a transmissivity of less than 5 ft2/d, a width of 10 mi, 

and a gradient of 100 ft/mi.

Previous predevelopment discharge estimates from 

Saratoga Spring have differed by an order of magnitude, but 

primarily resulted from different areas being labeled Saratoga 

Spring. Saratoga Spring initially was identified as an area of 

23 acres that discharges 200 acre-ft/yr (Kunkel and Robinson, 

1966) and is discussed as Saratoga Pools in this report 

(fig. 14). Saratoga Spring also has been identified as a much 

larger area consisting of Saratoga Pools and mapped ET units 

(Faunt, Blainey, and others, 2010, p. 269, table F-4). Reported 

discharge from the larger Saratoga Spring area totaled 2,460 

acre-ft/yr (Faunt, Blainey, and others, 2010), which was 

estimated with remote sensing and extrapolated ETGW rates 

(DeMeo, and others, 2003). This estimate was biased high and 

likely occurred because ETGW rates were extrapolated from 

areas with denser vegetation than in the Saratoga Spring area.

Discharge from Saratoga Pools totaled 150 acre-ft/yr in 

this investigation. Kunkel and Robinson (1966) overestimated 

discharge (200 acre-ft/yr) from Saratoga Pools by applying 

an ETGW rate of 13 ft/yr to reeds, whereas rates of 8 ft/yr are 

more likely (Laczniak and others, 1999). DeMeo and others 

(2003) underestimated discharge (50 acre-ft/yr) from Saratoga 

Pools because about 13 acres of open water and reeds were 

not mapped. Discharge from Saratoga Pools was corrected 

in this investigation by assigning an ETGW rate of 8 ft/yr to 

the unmapped 13 acres, which increased total discharge from 

Saratoga Pools from 50 to 150 acre-ft/yr.

Predevelopment discharge from the Saratoga Spring area 

totaled 800–1,200 acre-ft/yr from a local water budget, and 

net discharge was less than 400 acre-ft/yr (table 4). Discharge 

from Saratoga Spring topographic basin was estimated 

by summing estimated inputs (recharge) and assuming 

that discharge equaled recharge. Minimum discharge was 

supported mostly by 720 acre-ft/yr of base flow infiltrating 

the Amargosa River channel downstream of Dumont Dunes, 

California (USGS streamgage 10251375). Estimated recharge 

from flood events (220 acre-ft/yr), local recharge (200 

acre-ft/yr), and subsurface bedrock leakage (50 acre-ft/yr) 

is uncertain, but minor compared to base-flow infiltration. 

Because the 720 acre-ft/yr of base-flow infiltration is derived 

from springs and seeps along the Amargosa River between 

Shoshone and Tecopa, including base-flow infiltration in the 

Saratoga Spring water budget would result in double-counting 

of groundwater between Lower Amargosa and Saratoga Spring 

discharge areas. Subtracting base-flow infiltration results in 

a net discharge of less than 400 acre-ft/yr for the Saratoga 

Spring area.

Recharge

Recharge is spatially and temporally variable in the study 

area. Spatially varying recharge is dependent on unsaturated 

zone depth, hydraulic conductivities of unsaturated and 

saturated rocks, and the distribution of precipitation, where 

higher altitudes receive more precipitation. Time-varying, 

or episodic, recharge is precipitation-derived and occurs 

during brief intermittent periods that cause distinct waterlevel rises in well hydrographs. Conceptual models of spatial 

and temporal recharge in the study area are discussed in the 

following sections.
Predevelopment Groundwater Flow 35

Spatially Distributed Long-Term Rates 

A recharge distribution was estimated for the study 

area based on a conceptual model of water availability and 

permeability of rocks in recharge areas. Rates of infiltration 

below the root zone were assumed related to precipitation 

rates and increased as precipitation rates increased. Recharge 

rates were assumed equal to infiltration rates below the root 

zone, except where runoff occurs from surface-water flow 

or subsurface flow. Precipitation-runoff (surface-water flow) 

occurs when snowmelt runoff or high-intensity rainfall flows 

downgradient from low-permeability rocks in highland areas 

and infiltrates adjacent, permeable, alluvial-fan deposits or 

basin fill in ephemeral channels. Subsurface flow occurs 

when discontinuous low-permeability rocks form perched 

intervals above the regional water table. Subsurface flow is 

assumed to move laterally within the perched system until 

sufficiently permeable, saturated rocks of the regional system 

are encountered that can be recharged by the infiltrated water.

The conceptual model of total annual recharge to the 

study area is a modified Maxey-Eakin (Maxey and Eakin, 

1951) approach that honors the annual predevelopment 

discharge, which ranges from 53,600 to 54,900 acre-ft/yr 

(table 4). Distributed recharge is conceptualized as a piecewise 

linear function of total annual precipitation, as defined by the 

1981–2010 PRISM precipitation distribution (PRISM Climate 

Group, 2012). A three-stage relation is assumed to exist 

between precipitation and total potential recharge. Potential 

recharge includes in-place infiltration, precipitation-runoff, 

and runoff by subsurface flow. The assumed relation exists 

for a precipitation rate of 0.3–2.5 ft/yr, which is the range of 

annual precipitation estimates in the study area (fig. 15). The 

water available for recharge was estimated from precipitation, 

where stages are demarcated by inflection points at annual 

precipitation rates of 1.0 and 1.5 ft/yr (fig. 15A). Proportions 

of recharge increase from 0 to 0.9, 0.9 to 4.6, and 4.6 to 41 

percent of annual precipitation in the ranges 0.3–1.0, 1.0–1.5, 

and 1.5–2.5 ft/yr of precipitation. Relations between total 

conceptual recharge and precipitation in excess of 1.0 and 

1.5 ft/yr were adjusted for each groundwater basin so that the 

cumulative volume of annual recharge equaled net discharge 

from each groundwater basin and the study area as a whole.

The three-stage relation approximates conceptual 

differences in water availability even if the inflection points of 

1.0 and 1.5 ft/yr for changes in slope are arbitrary. Infiltration 

of runoff from summer storms is the primary mechanism for 

generating recharge at low elevations, where precipitation 

rates are less than 1 ft/yr. Summer storms occur infrequently 

and much of the water is lost to ET, resulting in a low ratio of 

precipitation converted to recharge. About 20 percent (12,000 

acre-ft/yr) of the total recharge in the study area occurs in 

areas with precipitation rates of less than 1 ft/yr (fig. 15B). At 

higher altitudes where precipitation rates are more than 1 ft/yr, 

winter snowpack generates most of the recharge and a higher 

ratio of the precipitation is converted to recharge. Efficiencies 

increase where precipitation rates are more than 1.5 ft/yr 

because ET losses decrease as altitude increases. All water 

that infiltrates below the root zone is assumed to migrate to the 

water table in the absence of low-permeability bedrock at the 

water table.

Except for surface-water channels, recharge is assumed 

not to occur on valley floors (French and others, 1996), 

which were defined as areas with land-surface slopes less 

than 1.5 percent. The valley floors have clay-rich soils, low 

precipitation rates, and warm air temperatures, which promote 

retention of soil water and ET.

Recharge volumes are limited where hydraulic 

conductivity of bedrock is less than infiltration rates. Recharge 

rates cannot exceed hydraulic conductivity of saturated rocks, 

which results in excess infiltration being displaced laterally 

downgradient (Fenelon and others, 2008) in Cactus, Kawich, 

Belted, Groom, Eleana, and Greenwater Ranges and areas of 

the Spring Mountains (fig. 16).

Precipitation-Runoff

Infiltration is limited where low-permeability rocks 

occur at land surface and precipitation-runoff flows laterally 

downgradient until more permeable rocks are encountered. 

Recharge rates of 0.004 ft/yr (0.00001 ft/d) were assumed for 

low-permeability bedrock and excess infiltration was displaced 

downgradient to where more permeable rocks could accept 

the water. The excess infiltration available for recharge from 

precipitation-runoff was halved and then applied to permeable 

rocks because additional evaporative losses occur in alluvial 

channels.

Focused recharge occurs beneath channels of the 

Amargosa River and Fortymile Wash during infrequent flood 

events (fig. 16). Annual volumes of infiltration have been 

estimated for reaches of the Amargosa River from Beatty 

to the central Amargosa Desert, from Eagle Mountain to 

Shoshone, and from Dumont Dunes to the Saratoga Spring 

area. Infiltration to the Amargosa River from Beatty to the 

central Amargosa Desert ranges from 80 to 100 acre-ft/yr2

(Stonestrom and others, 2007). Infiltration to the Amargosa 

River from Eagle Mountain to Shoshone is less than 700 

acre-ft/yr (Osterkamp and others, 1994). Infiltration to the 

Amargosa River from Dumont Dunes to the Saratoga Spring 

area totals 920 acre-ft/yr, where about 720 acre-ft/ yr is 

reinfiltrated groundwater that originally discharged into the 

Amargosa River upstream of Dumont Dunes, California 

(USGS streamgage 10251375). Infiltration estimates to 

Fortymile Wash plausibly are about 900 acre-ft/yr (Osterkamp 

and others, 1994) and have ranged from 90 to 6,550 

acre-ft/yr (Czarnecki and Waddell, 1984; French and others, 

1996; Savard, 1998).

2

 Infiltration rates were miscalculated in Stonestrom and others (2007) 

because recharge-rate fractions of 12 and 15 percent were multiplied by the 

4-year (1998–2001) total of streamflow from table 3 of that report, rather than 

by the annual average streamflow.
36 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4322_fig 15

0

0.5

1.0

1.5

Potential infiltration and runoff, 

in feet per year

A

0

20

40

60

80

100

0

10

20

30

40

50

60

0 0.5 1.0 1.5 2.0 2.5 3.0

Cumulative recharge, in percent

Cumulative recharge,

in thousands of acre-feet per year

Precipitation, in feet per year

B

Figure 15. Relation between precipitation rate and (A)

conceptual recharge rate from infiltration and runoff to the study 

area, and (B) cumulative recharge resulting from this relation, in 

the study area, Nevada and California.

Perched and Semi-Perched Groundwater

Infiltrated water moves laterally in the subsurface where 

more permeable rocks permit infiltration near land surface 

and less permeable rocks at depth limit recharge, resulting in 

perched or semi-perched conditions. Perched groundwater is 

a localized, unconfined, saturated volume of groundwater that 

is separated from the underlying regional groundwater system 

by an unsaturated zone of discontinuous low-permeability 

rocks. Semi-perched groundwater is similar to perched 

groundwater, except that the discontinuous low-permeability 

rocks are saturated. Perched (and semi-perched) intervals 

impede infiltration because vertical hydraulic conductivities 

of underlying low-permeability rocks are less than local 

infiltration rates, which impounds water and laterally diverts 

flow. Subsurface flow moves downgradient atop discontinuous 

low-permeability rocks until permeable saturated rocks of the 

regional groundwater system are encountered. Perched and 

semi-perched intervals conceptually redistribute recharge, 

with less recharge beneath and more at the peripheries of 

the perched and semi-perched intervals. Recharge rates of 

0.004 ft/yr (0.00001 ft/d) were assumed for low-permeability 

bedrock and excess infiltration from subsurface flow was 

displaced downgradient to where more permeable rocks could 

accept the water.

In this investigation, the water table encompasses the 

uppermost occurrence of saturation, which includes perched 

and semi-perched intervals. Inclusion of perched and semiperched intervals affects conceptual models of recharge 

and is a practical necessity to simulate advective flow from 

the locations of nuclear tests beneath Rainier Mesa (U.S. 

Department of Energy, 2018). Advective movement from 

Rainier Mesa cannot be addressed if the locations of nuclear 

tests are not in the groundwater model of the study area.

 Temporal Variability

Predevelopment conditions are analyzed as steady state 

in this investigation, which assumes recharge and natural 

discharge differ negligibly. This steady-state assumption is 

true if time-varying recharge is averaged over centuries. A 

long-term average is used because multi-decade water-level 

rises in wells have resulted from short-term imbalances 

between recharge and discharge (Fenelon and Moreo, 2002; 

Elliott and Fenelon, 2010; Fenelon and others, 2012; Jackson 

and Fenelon, 2018). Short-term (decadal) water-level changes 

generally can be ignored because spatial gradients are affected 

minimally, and water-level changes from natural stresses 

are small relative to pumping effects. Water-level changes in 

Devils Hole and wells throughout the Ash Meadows discharge 

area were the exception because natural changes were similar 

in magnitude to pumping effects. These natural changes were 

simulated and differentiated analytically from pumping effects 

with water-level models (Halford and others, 2012). Natural 

water-level changes were not simulated numerically because 

hydraulic-property estimates would have been degraded.

A water-level model simulates measured water levels in 

a well by summing analytically solved water-level changes 

from recharge, natural discharge, and pumping. This technique 

has been used effectively by Jackson and Fenelon (2018) to 

determine stresses affecting water-level trends and can be 

used to subtract time-varying recharge from the water-level 

trend in a well. The water-level modeling approach requires 

a conceptual model of recharge to explain rising water-level 

trends based on recharge patterns in the study area.

A conceptual model of time-varying recharge and 

natural discharge was used to explain the behavior of waterlevel trends in the study area prior to development. Water 

levels fluctuate naturally in response to short-term (hourly to 

seasonal) hydrologic stresses; therefore, a sufficiently long 

timescale is required to achieve steady-state conditions. As a 

rule of thumb, small groundwater basins have short steadystate timescales, whereas large groundwater basins, such as 

those within the study area, have long steady-state timescales. 

Jackson and Fenelon (2018) assumed that steady-state 

conditions occur on a century timescale in the study area based 

on available water-level data. The conceptual model requires 

a long-term (century-scale) precipitation record to represent 

recharge patterns in the study area, and this precipitation 

record is used to construct a hypothetical water-level record to 

explain steady-state water-level trends.
Predevelopment Groundwater Flow 37

sac19-4233_fig 16

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Eagle

Mtn

Devils Hole

USFWS 

DR-1

U-19bk

EXPLANATION

Observation well or site

Groundwater basin 

boundary modified from 

Fenelon and others (2016)

Nevada National Security 

Site boundary and 

internal operations areas

Conceptual distribution of 

recharge rates, in feet per 

day—Percentage of total 

recharge shown in 

parentheses

Recharge zone used in 

DV3 model calibration 

to estimate recharge 

rates

0.0001 to 0.002 (3%)

0.002 to 0.02 (21%)

0.02 to 0.2 (42%)

0.2 to 2 (34%)

Negligible recharge (0%)

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 115°30'

37°

30'

36°

30'

Dumont

Dunes

Figure 16. Conceptual recharge distribution, in the study area, Nevada and California.
38 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

The conceptual model postulates that long-term waterlevel fluctuations in predevelopment groundwater systems 

indicate changes in storage that result from differences 

between recharge entering the system and discharge leaving 

the system. In the Great Basin and the study area, more 

specifically, most natural discharge occurs at springs, seeps, 

and phreatophyte areas distant from the recharge areas. This 

regional discharge is nearly constant from year to year because 

the regional gradient that controls changes in discharge is 

insensitive to local water-level fluctuations of less than 50 

ft in recharge areas relative to greater than 1,000-ft-head 

differences along flow paths between recharge areas and 

distant discharge areas. Unlike discharge, recharge varies 

temporally, and is the primary cause of annual-to-decadal, 

water-level fluctuations in the aquifer, as measured in wells.

Recharge principally occurs during winter months 

between October and March, in years with greater-thanaverage precipitation. This is because minimal ET occurs 

during the winter, which allows infiltrating precipitation to 

exceed the storage capacity of the root zone and infiltrate 

below the root zone (Smith and others, 2017). More recharge 

also occurs during winter months because surface runoff is less 

in areas where snow falls, and the slow melting of snowpack 

allows more time for infiltration compared to relatively brief 

rainfall events. Stable-isotope analyses of precipitation and 

shallow groundwater at Rainier Mesa (Russell and others, 

1987; Hershey and others, 2008) and the Spring Mountains 

(Winograd and others, 1998) have indicated that most recharge 

is derived from winter precipitation. During a winter with 

less-than-average to slightly above-average precipitation, 

infiltrating precipitation mostly or entirely contributes to the 

soil-moisture reservoir depleted by ET during the previous 

summer. In these years, little to no water infiltrates beyond 

the root zone. Following winters with greater-than-average 

precipitation (wet winters), snowmelt infiltrates the root zone, 

wetting the soil sufficiently to exceed its field capacity and 

allows percolation downward to recharge the groundwater 

system (Smith and others, 2017).

A simple conceptual model of steady discharge and 

episodic recharge explains expected water-level trends prior 

to groundwater development (Jackson and Fenelon, 2018). 

Discharges are conceptualized as steady because water-level 

gradients and regional discharges are relatively invariant 

between decades. Episodic recharge events are approximated 

with precipitation during winter months that exceeds a 

threshold. Estimated recharge events from the precipitationthreshold model were correlated with infiltration below the 

root zone. Winter precipitation greater than a defined threshold 

infiltrates below the root zone, passes through the unsaturated 

zone, and ultimately becomes recharge at the water table in the 

conceptual model (Smith and others, 2017).

A precipitation index of monthly precipitation for 

south–central Nevada (Western Regional Climate Center, 

2016) was used to examine century-scale precipitation trends 

and resultant recharge trends. Although the precipitation 

index does not represent the true magnitude of precipitation 

in the study area, the relative patterns of wet and dry years 

in south–central Nevada are similar. Recharge is defined as 

winter precipitation in excess of a threshold that approximates 

the volume of the root zone. This simple water balance 

assumes that all moisture evaporates from the root zone prior 

to October of each year. In the example for south–central 

Nevada, excess winter precipitation (recharge) during wet 

winters is defined as 125 percent of the long-term average 

(1900–2016), where long-term average precipitation is 4.8 in. 

(fig. 17A). A threshold of 125 percent (6 in.) resulted in the 

occurrence of wet winters about 20 percent of the time from 

1900 to 2016 (fig. 17B). Notably, wet conditions after 1968 

generated nearly 70 percent of the recharge for the 117-year 

period. The 125-percent threshold used is arbitrary. Thresholds 

of 100 or 150 percent of the long-term average produce similar 

long-term recharge patterns.

Jackson and Fenelon (2018) derived a hypothetical 

long-term water-level record to explain expected steady-state 

water-level trends in the study area. The hypothetical waterlevel record is the sum of two components: water-level change 

resulting from recharge and water-level change resulting from 

aquifer discharge. The water-level change from recharge was 

calculated as the sum of excess winter precipitation using a 

125-percent threshold divided by an effective porosity of 10 

percent. Selection of a larger or smaller effective porosity 

would result in a smaller or larger magnitude of water-level 

change, respectively. However, the hypothetical waterlevel trend would remain unchanged. Cumulative waterlevel increase from recharge equals about 30 ft over 117 

years. Cumulative aquifer discharge was assumed equal in 

magnitude to cumulative recharge during the 117-year period; 

therefore, water-levels declined 0.26 ft/yr from discharge. 

Hypothetical water levels declined prior to 1970 because 

aquifer discharge exceeded recharge during persistent dry 

conditions. Hypothetical water levels rose from 1970 to 2016 

because recharge exceeded discharge in response to frequent 

wet winters (fig. 17).

In areas distant from groundwater development, the 

longest consistent water-level records (1990s to 2018) show 

that water levels have been rising in the study area and 

throughout southern Nevada (Fenelon and Moreo, 2002; 

Elliott and Fenelon, 2010; Fenelon and others, 2012; Jackson 

and Fenelon, 2018). For example, rising water-level trends 

are observed in well U-19bk, open to volcanic rocks in Pahute 

Mesa, and well USFWS DR-1, open to carbonate rocks near 

the Sheep Range (figs. 16 and 18).
Predevelopment Groundwater Flow 39

sac19-4322_fig 17

Recharge

0

5

10

Winter precipitation, in inches 

A

Water-level

change 

Cumulative

recharge 

Cumulative

discharge 

-30

-20

-10

0

10

20

30

1900 1920 1940 1960 1980 2000 2020

Water-level change, in feet

Year

B

Evapotranspired

Figure 17. Winter precipitation (October–March) and excess winter precipitation (recharge) using 

125-percent threshold (A), and hypothetical water-level change under predevelopment (steady-state) 

conditions (B), in the study area, Nevada and California, 1900–2016. Threshold of 125 percent of 

long-term average is an arbitrary threshold used to designate a “wet winter.” Hypothetical waterlevel change under predevelopment conditions is the sum of cumulative recharge from 1900 to 2016 

and constant discharge. Precipitation data from south-central Nevada precipitation index (Western 

Regional Climate Center, 2016). DV3, Death Valley version 3. Figure modified from Jackson and Fenelon 

(2018).
40 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig18

Water-level model

Measured water-levels

EXPLANATION

A. USGS 371714116230301 147 S07 E50 34 1 U -19bk

B. USGS 363332115244001 212 S16 E58 14A 1 USFWS DR-1

812

814

816

818

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

1,983

1,985

1,987

Depth to water, in feet below land surface

Year

Figure 18. Measured water levels and water-level models for wells U-19bk and USFWS DR-1, in the study 

area, Nevada and California, 1910–2018.

Water-level models show that rising trends in wells 

U-19bk and USFWS DR-1 can be attributed to precipitationderived recharge from a series of wet winters (Jackson and 

Fenelon, 2018). Water-level models simulated rising trends 

by fitting an analytical model of recharge and discharge 

to measured water levels. Recharge was simulated using 

winter precipitation (October–March) in excess of 6 in. from 

the south-central Nevada precipitation index (fig. 17AA). 

Discharge was assumed to be constant and was simulated 

as a linear decline. The fit of the water-level models to the 

measured data in wells U-19bk and USFWS DR-1 compare 

favorably (fig. 18), indicating that rising trends can be 

explained by recharge and discharge. The poor fit in both 

models prior to 1996 is attributed to less accurate (±1 ft) 

water-level measurements (Elliott and Fenelon, 2010).

Water levels in most, if not all, wells would have rising 

trends if groundwater development never occurred in the 

study area. Water levels in wells within pumping areas have 

declining trends because the magnitude of water-level decline 

from pumping has exceeded water-level rises from recharge.

Hydraulic Conductivity

Spatial variations in hydraulic conductivities of saturated 

rocks control water-level gradients and flow rates between 

recharge and discharge areas. Spatially distributed hydraulic 

conductivities must be estimated throughout the study area 

to simulate groundwater flow. The hydraulic-conductivity 

distribution encompasses the lateral and vertical extent of 

saturated rocks in the aquifer system.
Predevelopment Groundwater Flow 41

Hydraulic conductivities are estimated indirectly from 

pumping aquifer tests. Each aquifer test is a controlled field 

experiment (Stallman, 1971) because water is pumped at a 

known rate and resulting water-level declines, or drawdowns, 

can be interpreted with an analytical or numerical model. 

Transmissivity estimates are the most prevalent and 

reliable aquifer-test result. Hydraulic conductivity equals 

transmissivity divided by aquifer thickness or well screen 

length. Aquifer thickness is assumed to be equal to well screen 

length in areas where transmissivity is less than 1,000 ft2/d 

or small volumes of water are pumped (less than 100,000 

gal), whereas the aquifer thickness is used for saturated rocks 

where transmissivity exceeds 1,000 ft2/d or large volumes of 

water are pumped (more than 100,000 gal, such as pumping 

at 100 gal/min for 1 day) (Halford and others, 2006). Aquifer 

thickness frequently is unknown at a field site, which is a 

source of uncertainty; however, aquifer thickness is defined in 

a hydrogeologic framework model, which is based on geologic 

data and interpretations. Relating the product of groundwatermodel-estimated hydraulic conductivities and assigned 

hydrogeologic framework model thicknesses to field-estimated 

transmissivities reduces this uncertainty.

Transmissivity estimates from aquifer tests can be 

extrapolated throughout the study area by correlating 

hydraulic conductivity with mappable hydrogeologic units. 

These hydrogeologic units theoretically have unique hydraulic 

variability or transport properties compared to other units 

(Mirus and others, 2016). Unique hydraulic variability within 

a hydrogeologic unit is defined as a hydrogeologic unit having 

a hydraulic-conductivity probability distribution that does not 

sufficiently overlap with the hydraulic-conductivity probability 

distributions of other hydrogeologic units.

More hydrogeologic units have been defined than can 

be supported hydrologically in previous studies (fig. 3). This 

was suggested by disagreement between estimated geometric 

mean hydraulic conductivities and their conceptual ranking, 

where geometric means indicate that some confining units 

are more permeable than aquifers (fig. 3). Furthermore, 

probability distributions of hydraulic conductivity significantly 

overlap between multiple hydrogeologic units, indicating 

non-uniqueness in hydraulic variability. Relations between 

geologic units, hydraulic conductivity, and transmissivity are 

examined so that resulting hydrogeologic units have unique 

hydraulic variability in this investigation.

Reducing the number of hydrogeologic units is practical 

for the stated purpose of this investigation. Numerous 

hydrogeologic units originally were defined within complex 

hydrostratigraphic frameworks to allow for comprehensive 

evaluation of uncertainty in radionuclide transport predictions. 

However, these framework models have more hydrogeologic 

units than are needed to calibrate groundwater models. More 

hydrogeologic units hinder the calibration process because of 

incomplete data and computational burden.

Field Estimates of Transmissivity

Transmissivity can be estimated from single-well or 

multiple-well aquifer tests and from specific capacities. 

Single-well aquifer tests include pumping tests and slug tests. 

Multiple-well aquifer tests involve pumping one well and 

measuring water levels within the pumped well and nearby 

observation wells. Specific capacity is the pumping rate 

divided by drawdown at an unspecified time.

In this report, the terms “borehole” and “well” have 

specific definitions. A borehole refers to the mapped (X,Y) 

location where a hole was drilled, and the borehole may 

have more than one well. A well is a single, temporary or 

permanent, screened (or open) completion in a borehole. Many 

wells in the study area have multiple reported transmissivity 

estimates because multiple aquifer tests occurred, or an aquifer 

test was analyzed by multiple investigators (Frus and Halford, 

2018).

A single, representative transmissivity is estimated for 

each well in this investigation. Multiple-well aquifer test 

results are limited to a transmissivity that is attributed to the 

pumping well. In individual boreholes beneath Pahute Mesa, 

transmissivities were estimated from pumping aquifer tests, 

where the entire borehole was pumped, and from slug tests 

of 200-ft intervals of the open hole that were isolated with 

packers (Blankennagel and Weir, 1973). Transmissivities 

from only pumping aquifer tests were compared, where a 

pumping aquifer test and multiple slug tests occurred within a 

borehole. This was appropriate for characterization of geologic 

units and calibration of a regional groundwater model. Wells, 

construction, aquifer-test results, sources, and representative 

transmissivity estimates used in this study are summarized in 

Jackson and Halford (2020).

Transmissivities have been estimated from aquifer tests 

at 113 wells within the study area (fig. 19), where nearly 

all aquifer tests supported NNSS activities. Exploratory 

boreholes were drilled and tested in the 1960s primarily to 

identify low-permeability rocks suitable for the testing of 

nuclear devices underground (Blankennagel and Weir, 1973). 

Radionuclides potentially could migrate from underground 

nuclear tests and hydrologic studies began investigating 

potential migration within a few years of the first underground 

nuclear test in 1957 (Winograd and Thordarson, 1975, p. 

C1). Regional aquifers and confining units from Yucca Flat 

to the Ash Meadows discharge area were characterized with 

drilling and aquifer testing that included 10 wells completed 

in carbonate rocks (Winograd and Thordarson, 1975, p. C20). 

Aquifers and confining units in the nearby Yucca Mountain 

area also were characterized with drilling and aquifer testing 

for a proposed nuclear waste repository to store high-level 

radioactive waste and spent nuclear fuel (Craig and Robison, 

1984). Additional wells have been drilled and tested for water 

supplies that supported NNSS operations. After nuclear testing 

ceased in 1992, most aquifer tests have supported subsurface 

characterization to better estimate potential migration of 

radionuclides for the U.S. Department of Energy UGTA 

activity.
42 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 19

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Emigrant 

Valley

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Devils 

Hole

ER-20-7 U-15k Test Hole

Inyo-BLM 1

Inyo-BLM 2

ER-5-4-2

ER-5-3-2

ER-6-1-2 main ER-6-2

UE-10j (2232-2297 ft)

ER-8-1 (recompleted)

UE-25p1 (JF-2a)

UE-20f (4456-13686 ft)

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Observation well or site

Well with transmissivity 

estimate from single-well 

aquifer test. Wells ranked 

by transmissivity estimate, 

in feet squared per day 

Well with transmissivity 

estimate from specific 

capacity. Wells ranked by 

transmissivity estimate, in 

feet squared per day

Less than 100

100 to 10,000 

More than 10,000

Less than 100

100 to 10,000 

More than 10,000

ER-6-2

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Universal Data. Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

ER-EC-14 main 

lower zone

Black Mountains

Figure 19. Transmissivity estimates from single-well aquifer tests and specific capacity, in the study area, Nevada and 

California.
Predevelopment Groundwater Flow 43

Transmissivity estimates characterize a volume of aquifer 

rather than a point. The volume of aquifer sampled generally 

is proportional to the volume of water pumped or displaced. 

For example, 2,400,000 gal were pumped from well ER-20-7

(fig. 19) and drawdowns were detected as far away as 2 mi 

from the pumping well. Likewise, 7,000,000 gal were pumped 

from well ER-EC-14 main lower zone (fig. 19) and drawdowns 

were detected more than 4 mi from the pumping well. In a 

simplistic example, if it was assumed that the 4-mi drawdown 

distance in the latter aquifer test represented the radius of a 

spherical capture volume, then the transmissivity estimated 

from this test would characterize a 268-mi3 volume of aquifer. 

Of the 113 aquifer tests, 83 were pumping aquifer tests, where 

a median volume of 700,000 gal was pumped during each test 

(fig. 20).

Transmissivities from low-permeability units were 

estimated primarily with slug tests because only limited 

volumes of water could be removed. Transmissivities of 

0.00002–1 ft2/d were estimated exclusively with slug tests. The 

median volume displaced from slug testing was about 400 gal 

(fig. 20), which is large relative to typical slug-test volumes of 

less than 1 gal. Relatively large displacement volumes resulted 

from initial displacements exceeding 1,000 ft (Frus and 

Halford, 2018) or evacuation of wells with diameters greater 

than 50 in. during slug tests. Recovery periods for many slug 

tests exceeded 1 year, with the longest period exceeding 20 

years in well U-15k Test Hole (fig. 19). Investigated radial 

distances of slug tests remained considerably less than the 

influence of pumping aquifer tests (Frus and Halford, 2018). 

A transmissivity estimated from tidal-forcing of water levels 

in well Inyo-BLM 1 (fig. 19; Cutillo and Bredehoeft, 2011) 

was classified as a slug test because less than 1 gal of water 

was displaced.

Transmissivity estimates from pumping aquifer tests 

in siliciclastic rocks and zeolitized tuffs likely represent 

permeable inclusions in otherwise low-permeability rocks. 

Biased results were suggested by transmissivity estimates 

decreasing during later analysis periods and locally 

inconsistent water levels. For example, well ER-5-4-2 (fig. 19) 

is open to zeolitized tuff 4,850–7,000 ft below Frenchman 

Flat and 2,200,000 gal were pumped during a 10-day test. 

Transmissivities of 200 and 60 ft2/d were estimated during 

periods 0–1 and 2–6 days after pumping started, respectively, 

with Cooper-Jacob (1946) analyses. Transmissivities of 13 

and 6 ft2/d were estimated during periods 0.3–4 and 4–15 

years after pumping stopped, respectively, with Cooper-Jacob 

recovery analyses. The water-level altitude in well ER-5-4-2

exceeds 2,480 ft, which is 70 and 90 ft higher than waterlevel altitudes in overlying basin fill and adjacent carbonate 

rocks, respectively. The water-level altitude in well ER-5-4-2

unlikely represents predevelopment conditions within the 

last 500 years and is best explained as incomplete drainage 

from past pluvial conditions. Sustaining 70- to 90-ft head 

differences during a 10,000-yr period of drainage requires an 

average hydraulic conductivity of less than 0.00001 ft/d, or 

300 times less than the smallest estimate from the aquifer test, 

when converted to a hydraulic conductivity (0.003 ft/d).

Transmissivities also were estimated empirically 

from 158 specific-capacity estimates using a local powerlaw relation for Pahute Mesa (Frus and Halford, 2018). 

Transmissivity (foot squared per day) equaled 380 times 

specific capacity (gallons per minute per foot) and was 

developed with results from 39 Pahute Mesa pumping 

aquifer tests. Greater than 80 percent of 39 transmissivities 

estimated with the Pahute-Mesa relation were within a factor 

of five from aquifer-test results. The Pahute-Mesa relation 

functionally differs little from other empirical relations 

developed in California and northern Nevada (Thomasson and 

others, 1960; Yager and others, 2012). Greater than 70 percent 

of the 158 specific-capacity estimates sampled large volumes 

of aquifer because more than 100,000 gal were pumped 

(fig. 20).

Transmissivities outside the NNSS were estimated 

predominantly from specific capacities using well logs 

(Nevada Division of Water Resources, 2018). Reported 

pumping rates (gallons per minute) and water-level declines 

(feet) were used to minimize spurious specific-capacity 

estimates from domestic wells. For example, specific-capacity 

estimates were reported for 4,442 of 12,226 well logs in 

Pahrump Valley, where 3,582 wells had a reported pumping 

rate of 20 gal/min with a drawdown of 4 ft. To eliminate 

questionable specific-capacity estimates, wells with pumping 

rates less than 30 gal/min or water-level declines less than 

10 ft were not used in this study, which reduced the number 

of specific-capacity estimates from 4,442 to about 300. The 

number of useful specific capacities declined from about 300 

to 129, after each of the remaining well logs were read. Most 

of the specific capacities were rejected because bailed volumes 

were reported as pumping rates, such as the removal of 5 

gal of water being reported as a pumping rate of 5 gal/ min. 

The 129 specific-capacity estimates primarily were from 

irrigation wells in the central Amargosa Desert and Pahrump 

Valley (fig. 19). The 129 specific-capacity estimates were 

computed from pumping rates that averaged 700 gal/min, 

with a maximum of 3,500 gal/min. Specific capacities ranged 

from 0.01 to 400 gal/min/ft and transmissivities from specific 

capacities ranged from 4 to 160,000 ft2/d.
44 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig20

0

50

100

0.3 to 100 100 to 1,000 1,000 to 10,000 10,000 to

100,000

100,000 to

1 million

1 million to

10 million

10 million to

370 million

Count of transmissivity estimates

Volume pumped or displaced, in gallons

Slug test

Pumping aquifer test

Specific capacity

EXPLANATION

Figure 20. Volume of water pumped or displaced from single-well aquifer tests (pumping and slug tests) and 

specific capacity, in the study area, Nevada and California.

Transmissivity and Rock Type

Relations between transmissivity and rock type were 

investigated using four broad categories that group previously 

defined hydrogeologic units from DVRFS.v2 (table 6). 

Previous investigations (fig. 3) and limited data for some 

hydrogeologic units suggest that only four broad categories of 

rock type can be related to transmissivity: (1) carbonate rocks; 

(2) volcanic rocks; (3) basin fill; and (4) low-permeability 

rocks. Carbonate rocks were not further subdivided because 

few wells penetrate the localized, upper carbonate aquifer. 

Volcanic rocks were not subdivided because distributions of 

log-hydraulic conductivity were similar in younger volcanic 

and Tertiary volcanic units (fig. 3). Probability distributions 

overlapped considerably where the Tertiary volcanic unit was 

differentiated into eight hydrogeologic units (Belcher and 

others, 2002; p. 12). Log-hydraulic conductivity distributions 

of alluvial aquifer and alluvial confining unit differed little 

(fig. 3); therefore, units were grouped into a single category 

of basin fill. Low-permeability rocks consist of granitic rocks, 

siliciclastic rocks, and older volcanic rocks, which form the 

basement of the study area. Low-permeability rocks were not 

further subdivided because there were only a small number of 

transmissivity estimates.

Log-transmissivity distributions for carbonate rocks, 

volcanic rocks, basin fill, and low-permeability rocks do 

not sufficiently overlap, indicating hydraulic uniqueness 

(fig. 21). Median transmissivities of carbonate rocks, volcanic 

rocks, and basin fill are all near 1,000 ft2

/d but variability 

differs markedly. Transmissivity of basin fill was the most 

predictable, with a 95-percent confidence interval that ranged 

from 40 to 20,000 ft2/d. Transmissivity of volcanic rocks was 

the least predictable, with a 95-percent confidence interval 

that ranged from 0.006 to 60,000 ft2/d. Rock type most reliably 

establishes a maximum transmissivity that likely would 

be present at a site (fig. 21). Transmissivity estimates were 

analyzed, in preference to hydraulic conductivity, because 

contributing aquifer thickness generally was unknown.

Transmissivity and Thickness

Thickness and transmissivity are not correlated regardless 

of definition of thickness or rock type (fig. 22). Thickness 

alternatively was defined by length of open interval or 

thickness of rock type penetrated by the well. Thicknesses 

of rock types were the summation of hydrogeologic 

unit thicknesses for each rock type from the DVRFS.

v2 hydrogeologic framework (Belcher and others, 2017). 

Observed rock types in 25 of 271 wells were misclassified 

in the hydrogeologic framework. Misclassification errors 

occurred too infrequently to explain the lack of correlation. 

Spatial variability in transmissivity can be attributed almost 

exclusively to variability in hydraulic conductivity. This 

suggests that refining thicknesses of hydrogeologic units 

further will minimally benefit future hydrologic investigations. 
Predevelopment Groundwater Flow 45

Table 6. Relation between simple-rock types and previously defined hydrogeologic units in the Death 

Valley Regional Flow System version 2 model (DVRFS.v2) hydrogeologic framework, Nevada and California.

[Source: Belcher and others (2017)]

Rock type DVRFS.v2 abbreviation DVRFS.v2 hydrogeologic unit

Carbonate rocks UCA Upper carbonate-rock aquifer 

LCA_T1 Lower carbonate-rock aquifer (thrusted)

LCA Lower carbonate-rock aquifer 

Volcanic rocks LFU Lava-flow unit

YVU Younger volcanic-rock unit 

TMVA Thirsty Canyon-Timber Mountain volcanic-rock aquifer 

PVA Paintbrush volcanic-rock aquifer 

CHVU Calico Hills volcanic-rock unit 

WVU Wahmonie volcanic-rock unit 

CFPPA Crater Flat–Prow Pass aquifer 

CFBCU Crater Flat–Bullfrog confining unit 

CFTA Crater Flat–Tram aquifer 

BRU Belted Range unit 

Basin fill YAA Younger alluvial aquifer

YACU Younger alluvial confining unit 

OAA Older alluvial aquifer 

OACU Older alluvial confining unit 

LA Limestone aquifer 

VSU upper Upper volcanic-sedimentary rock unit 

Low-permeability rocks OVU Older volcanic-rock unit 

VSU lower Lower volcanic-sedimentary rock unit 

ICU Intrusive-rock confining unit 

SCU Sedimentary-rock confining unit 

UCCU Upper clastic-rock confining unit 

LCCU_T1 Lower clastic-rock confining unit (thrusted)

LCCU Lower clastic-rock confining unit 

XCU Crystalline-rock confining unit 

Basin fill in the Amargosa Desert was differentiated 

previously for the stated reason of “...improved understanding 

of the hydrogeologic system.” (Taylor and Sweetkind, 2014, 

p. 1.) Grain size, sorting, and texture were inferred from 210 

drillers’ logs to define 28 unique lithologic classes. These 

refined lithologic classes replaced previously defined basinfill hydrogeologic units in the DVRFS.v2 model and were 

assigned relative permeabilities of low, moderately low, or 

high (Belcher and others, 2017, p. 13). High-permeability 

classes were composed of gravel, sand, or freshwater 

limestone, which presumably would be correlated with high 

specific capacities or transmissivities. Specific capacities 

were reported on 50 of the drillers’ logs and used to test the 

hydrologic utility of finely differentiating basin fill.

Finely differentiated basin fills poorly predicted specific 

capacities in the Amargosa Desert, regardless of how 

permeable classes were assigned (fig. 23). High permeability 

from Belcher and others (2017, p. 13) defined a test group. A 

second test group combined all classes dominated by gravel or 

sand. Effective thicknesses of each of the 24 lithologic classes 

were estimated independently in a third test group, where 

the effective thickness was the coarse-grained fraction of the 

saturated thickness. Coefficient of determination (r2

) was less 

than 0.01 regardless of whether thicknesses were compared 

to specific capacities or log-specific capacities. Independently 

estimating an effective thickness for each of 24 classes 

improved r2 to 0.39, but the results were nonsensical. This was 

because specific capacity increased as effective thickness of 

permeable sediments decreased (fig. 23).
46 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig21

Transmissivity, in feet squared per day

Carbonate rocks (30)

Volcanic rocks (77)

Basin fill (149)

Low-permeability rocks (13)

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1,000 10,000 100,000 1,000,000 10,000,000

EXPLANATION

95-percent confidence interval

50 percentile

Minimum Maximum

Note: Number of transmissivity estimates for each rock type is shown in parentheses.

Figure 21. Minimum, maximum, median, and 95-percent confidence interval of log-transmissivities in four rock-type 

categories from 271 field estimates of transmissivity, in the study area, Nevada and California.

Hydraulic Conductivity and Depth

Hydraulic conductivity is distributed heterogeneously 

with depth in carbonate and volcanic rocks, where few 

permeable intervals contribute most of the transmissivity in a 

well. Few flowing intervals have been detected with flow logs 

in carbonate rocks beneath Yucca Flat in wells ER-6-1-2 main

(Garcia and others, 2010), ER-6-2 (Stoller-Navarro Joint 

Venture, 2005a), and UE-10j (2232-2297 ft) (IT Corporation, 

1995) (fig. 19). About 10 percent of the combined 3,200 

ft of saturated thickness from the three wells contributed 

greater than 80 percent of flow. Depth-dependent variations 

in volcanic rocks beneath Pahute Mesa are well defined in 

17 boreholes, where these boreholes have an average depth 

of 6,200 ft below land surface (Blankennagel and Weir, 

1973). For each of these boreholes, interval transmissivities 

were estimated from packer testing 200-ft intervals and total 

transmissivities were defined by pumping aquifer tests. Most 

of the permeability occurred in about 2 percent of 74,800 ft of 

saturated borehole that was tested (Frus and Halford, 2018). 

Hydraulic variations are consistent with complex bedded and 

fractured rocks, which have been observed in boreholes and 

outcrops in the study area (Sweetkind and others, 2010, p. 

71). These observable hydraulic and structural heterogeneities 

cannot be represented adequately by simulating groundwater 

flow through thick, homogeneous, hydrogeologic units.

Greater than 90 percent of estimated hydraulic 

conductivity in carbonate and volcanic rocks occurs within 

1,600 ft (500 m) of the water table (fig. 24). To estimate 

hydraulic conductivity with depth, transmissivities from 

pumping aquifer tests were binned into 330-ft (100-m) 

saturated intervals of the wells for consistency in comparing 

carbonate and volcanic rocks. For example, consider a well 

open to 2,000 ft of carbonate rocks with a transmissivity 

of 1,000 ft2

/d. The 2,000 ft saturated open interval would 

be binned into six 330-ft saturated intervals, where each 

interval would have a hydraulic conductivity of about 0.5 ft/d. 

Transmissivity was distributed uniformly across open intervals 

in carbonate rocks because depth-dependent contributions 

were unknown in 23 of 26 wells. However, depth-dependent 

contributions have been estimated in volcanic rocks (Frus and 

Halford, 2018) and distributed accordingly. Interval-averaged 

hydraulic conductivity was the average transmissivity in each 

interval divided by interval thickness (fig. 24).
Predevelopment Groundwater Flow 47

sac19-4233_fig22

B. Volcanic rocks

C. Basin fill

D. Low-permeability rocks

0

10

20

A. Carbonate rocks

0

10

20

0

10

20

0

10

20

Transmissivity, in feet squared per day

Thickness, in thousands of feet

0.0001 0.001 0.01 0.1 1 10 100 1,000 10,000 100,000 1,000,000

Thickness estimated as 

length of open interval

EXPLANATION

Thickness of rock type estimated

from Death Valley Regional 

Flow System version 2 (DVRFS.v2) 

hydrogeologic framework

Figure 22. Relation between transmissivity and thickness of carbonate rocks, volcanic rocks, basin fill, and 

low-permeability rocks, in the study area, Nevada and California.
48 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig23

0.01

0.1

1

10

100

0 100 200 300 400 500

Specific capacity, in gallons per minute per foot

Thickness of sediments classed permeable, in feet

Gravel or sand dominant

Belcher and others (2017)

Effective thickness

EXPLANATION

Figure 23. Relation between specific capacity and thickness of basin fill classified as permeable in the 

Amargosa Desert, Nevada.

Hydraulic conductivity does not decrease smoothly as 

a function of depth below land surface as conceptualized in 

depth-decay models. These models assume that permeability 

decreases with depth as geostatic and hydrostatic load 

increases, which decreases widths of pore spaces and 

fracture apertures. Hydraulic conductivity previously has 

been correlated weakly with depth below land surface, 

where average hydraulic conductivity decreased by an order 

of magnitude with a 2,300-ft decrease in depth below land 

surface (Stoller-Navarro Joint Venture, 2004a, p. 5-30). The 

weak correlation had no predictive value because individual 

hydraulic-conductivity estimates ranged from 0.02 to 

100,000 ft/d within 2,300 ft of land surface (Stoller-Navarro 

Joint Venture, 2004a, p. 5-28). Unpredictable hydraulicconductivity variations at depth differences of less than 2,000 

ft below the water table and less than 5,000 ft below land 

surface are consistent with previous observations in carbonate 

rocks (Winograd and Thordarson, 1975, p. C20) and volcanic 

rocks (Blankennagel and Weir, 1973). Previous groundwater 

models in the study area (Belcher, 2004; Stoller-Navarro 

Joint Venture, 2009; Navarro-Intera, LLC, 2013; Belcher and 

others, 2017) have simulated vertical variations in hydraulic 

conductivity with depth-decay models despite available data.

Carbonate and volcanic rocks can be divided into shallow 

and deep rocks as an alternative to a depth-decay model. The 

division between shallow and deep rocks at 1,600 ft (500 m) 

below the water table is supported by depth-dependent 

hydraulic-conductivity data (fig. 24). Transmissive shallow 

rocks transmit most of the groundwater between recharge and 

discharge areas, whereas deep rocks have low-permeability 

and transmit a small component of the flow. The shallowdeep concept does not negate part of the groundwater budget 

because all flow from the active part of the groundwater 

system is included. The shallow-deep concept has been used 

previously within the study area (Fenelon and others, 2008, 

2010, 2012).
Predevelopment Groundwater Flow 49

sac19-4233_fig24

A. Carbonate rocks B. Volcanic rocks

(16)

(16)

(16)

(16)

(16)

(15)

(14)

(13)

(10)

(10)

(10)

(10)

(8)

(8)

(5)

(5)

0 10 20

(16)

(15)

(11)

(8)

(6)

(5)

(1)

(1)

(2)

(2)

(2)

(3)

(2)

(2)

(2)

(0)

0 10 20 30 40 50 60

0

1,000

2,000

3,000

4,000

5,000

Depth below water table, in feet

Transmissivity

averages

6,000 ft2

/d 

Transmissivity averages

70,000 feet squared 

per day (ft2

/d)

Number of contributing wells

Interval-averaged hydraulic conductivity, in feet per day

Figure 24. Average, depth-dependent hydraulic conductivity in volcanic and carbonate rocks, in the study 

area, Nevada and California.

The limited number of deep carbonate wells does not 

negate the concept of low-permeability carbonate rocks more 

than 1,600 ft below the water table. Six wells were completed 

in carbonate rocks at depths greater than 1,600 feet below 

the water table. Transmissivities in deep carbonate rocks 

ranged from 2 to 2,200 ft2/d and averaged 10 times less than 

transmissivities in shallow carbonate rocks. Wells ER-5-3-

2, Inyo-BLM 1, and UE-25p1 (JF-2a) (fig. 19) were drilled 

to test the concept of transmissive carbonate rocks at depth. 

However, the carbonate rocks encountered by these wells 

were not very transmissive, with transmissivities of 100–900 

ft2/d. Wells ER-5-4-2, ER- 8-1 (recompleted), and Inyo-BLM 2

(fig. 19) targeted, but never penetrated, transmissive carbonate 

rocks, and encountered low-permeability volcanic and granitic 

rocks. Although a rigorous evaluation of deep carbonate rocks 

is not possible, failed attempts to find transmissive intervals in 

deep carbonate rocks support the shallow-deep concept. The 

shallow-deep concept is supported by the substantial decrease 

in hydraulic conductivity with depth in 17 Pahute Mesa 

boreholes, where 16 of the 17 boreholes were completed in 

volcanic rocks at depths greater than 1,600 ft below the water 

table (fig. 24).

Hydrogeologic Framework

The hydrogeologic framework of the DV3 project is 

a simplification of the hydrogeologic framework from the 

DVRFS.v2 project (Belcher and others, 2017). The DVRFS.v2 

hydrogeologic framework integrates a regional hydrogeologic 

framework with CAU-scale frameworks for Frenchman 

Flat (Bechtel Nevada, 2005a), Yucca Flat–Climax Mine 

(Bechtel Nevada, 2006; Fenelon and others, 2012), Rainier 

Mesa–Shoshone Mountain (National Security Technologies, 

LLC, 2007; Fenelon and others, 2008), and Pahute Mesa 

(Bechtel Nevada, 2002; Garcia and others, 2017). The 

DV3 hydrogeologic framework simplifies the DVRFS.

v2 hydrogeologic framework (Belcher and others, 2017) 

by grouping hydraulically similar hydrogeologic units and 

limiting vertical discretization. 

Unlike the DVRFS.v2 hydrogeologic framework, the 

DV3 hydrogeologic framework included hydrologically 

mandated features and incorporated revisions to frameworks 

for Frenchman Flat, Yucca Flat–Climax Mine, and Rainier 

Mesa–Shoshone Mountain CAUs. An example of including a 

hydrologically mandated feature is explicitly mapping Furnace 

Creek Wash in the DV3 hydrogeologic framework. The 

DVRFS.v2 framework, polygons for modifying hydrogeologic 

unit extents by DV3 model layer, and the DV3 framework are 

available in Jackson and Halford (2020).
50 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Discretization 

The DV3 hydrogeologic framework grid is consistent 

with the numerical grid used in the groundwater models 

created for the DV3 project. The hydrogeologic framework 

for the DV3 project extends from the water table to 3,280 

ft (1,000 m) below the National Geodetic Vertical Datum 

of 1929 (NGVD 29), which encompasses all rocks with 

considerable permeability. This volume was discretized 

laterally into 268 rows of 221 columns of variably spaced, 

rectangular cells that ranged from 820 ft (250 m) to 4,920 ft 

(1,500 m) on a side. The volume was discretized vertically 

with deformed layers, where each cell was assigned a unique 

hydrogeologic unit. Hydraulically similar rock types with 

depth and computed vertical hydraulic gradients indicated that 

known gradients and hydrologic conditions can be simulated 

sufficiently with five layers.

Water-Table Surface

The DV3 hydrogeologic framework was developed to 

distribute hydraulic properties within the saturated rocks in 

the groundwater-flow models. The top of the hydrogeologic 

framework is the water table. In this report, the water table 

encompasses the uppermost occurrence of saturation, which 

includes perched intervals. The water-table surface was 

estimated from potentiometric maps and water levels in 

low-permeability ranges (IT Corporation, 1997; Fenelon and 

others, 2008, 2010, 2016).

The top of the saturated flow system in the DVRFS. v2 

project was defined differently than in the DV3 project 

(fig. 25). An undefined “idealized” potentiometric surface 

was the top of the saturated flow system in the DVRFS.v2 

project (Belcher and others, 2017, p. 17) that excluded higher 

altitudes of saturation in low-permeability ranges. Compared 

to the DVRFS.v2 project, the top of saturation of the DV3 

framework is 1,000 to 3,200 ft higher (fig. 25). Using the 

uppermost occurrence of saturation as the top surface of the 

DV3 hydrogeologic framework allowed for the simulation 

of major groundwater divides in the groundwater models. 

Unlike the DVRFS.v2 project, groundwater divides can be 

represented in the DV3 project in Bare Mountain, Eleana 

Ridge, north of Climax Mine, Skull Mountain, Sheep Range, 

Greenwater Range, and Black Mountains (fig. 25). Inclusion 

of perched groundwater also allowed for the simulation of 

advective flow from nuclear test locations in Rainier Mesa and 

Shoshone Mountain, which were detonated within the perched 

system (fig. 25).

Vertical Discretization

Vertical discretization of the DV3 hydrogeologic 

framework was the same as the groundwater-flow model. This 

differed from the DVRFS.v2 hydrogeologic framework, which 

was discretized independently of the groundwater-flow model 

grid. Hydrogeologic units were distributed in the DVRFS.v2 

framework by specifying tops and thicknesses. This permitted 

multiple hydrogeologic units to be present in each model 

cell. Hydraulic conductivities distributed with the DVRFS.v2 

hydrogeologic framework were translated to the groundwater 

model grid with the Hydrogeologic-Unit Flow (HUF) package 

of MODFLOW—a USGS modular hydrologic model software 

(Anderman and Hill, 2000). In each groundwater model cell, 

hydraulic conductivities from multiple hydrogeologic units 

were reduced to an equivalent hydraulic conductivity by 

assuming parallel flow in the horizontal direction and series 

flow in the vertical direction between hydrogeologic units.

The strength of the HUF package is the ability to use 

a hydrogeologic framework that has a different spatial 

discretization from the groundwater model. However, this 

strength is also a weakness because using different spatial 

grids introduces (sometimes unwarranted) complexity and 

can easily cause errors if not implemented correctly. When 

multiple hydrogeologic units occupy a MODFLOW model 

cell, the estimated effective hydraulic conductivity does 

not provide information on the hydrogeologic units that 

are behaving as aquifers or confining units. Parallel and 

series flow assumptions for computing equivalent hydraulic 

conductivities fail where dips of hydrogeologic-unit contacts 

and MODFLOW model layers depart more than a few 

degrees. This can transpose conceptual flow barriers and 

conduits in the groundwater model. Specifying tops and 

thicknesses of hydrogeologic units in the HUF package also 

can erroneously allow multiple hydrogeologic units to occupy 

identical volumes of aquifer, which is physically impossible 

and not checked by the HUF package.

The DV3 hydrogeologic framework was developed 

by first mapping hydrogeologic units from the DVRFS.v2 

framework (Belcher and others, 2017) to an intermediate grid. 

The intermediate grid was discretized vertically into uniform 

164-ft-thick (50-m-thick) layers. This assured that the volumes 

of the individual units would sum correctly to the total volume 

of the framework. The thickest hydrogeologic unit in each 

164-ft-thick cell was assigned to the cell. Hydrogeologic 

unit assignment was altered minimally because less than 3 

percent of the 164-ft-thick cells were intersected by more than 

one of the original hydrogeologic units from the DVRFS.v2 

framework.
Predevelopment Groundwater Flow 51

sac19-4233_fig 25

Devils Hole 

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

1,000

2,000

3,000

3,000

3,000

4,000

4,000

3,000

3,000

3,000

5,000

5,000

5,000

5,000

4,000

6,000

6,000

6,000

7,000

3,000

4,000

4,000

3,000

4,000

2,000

1,000

8,000

4,000

5,000

3,000

5,000

5,000

5,000 5,000

6,000

3,000

7,000

3,000

4,000

5,000

6,000

5,000

6,000

2,000 5,000

4,000

4,000

A A'

Cross-section 

extent in figure 26

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute

Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Skull 

Mountain

Shoshone 

Mountain

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Emigrant 

Valley

U-20 WW 

(cased)

ER-6-1-2 

main

ER-4-1

m1

EXPLANATION

EXPLANATION

Groundwater basin 

boundary modified from 

Fenelon and others (2016)

Nevada National Security 

Site boundary and 

internal operations areas

Area where hydrogeologic 

framework was modified 

based on lithologic well 

data

Simulated water-table 

contour—Altitude, in feet, 

of predevelopment water 

table in DV3 model. Contour 

interval is 1,000 feet. 

Difference, in feet, between watertable surface in DV3 and 

DVRFS.v2 hydrogeologic framework models—Positive 

differences indicate water-table 

altitude in DV3 is greater than 

altitude in DVRFS.v2 hydrogeologic framework model.

4,000

-2,000 to -1,000

-1,000 to -300

-300 to 300

300 to 1,000

1,000 to 3,200

Observation well or site

A A' Trace of section

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

um is National Geodetic Vertical Datum of 1929. 20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983. 

Vertical datum is National Geodetic Vertical Datum of 1929.

116°30' 115°30'

37°

30'

36°

30'

Dumont

Dunes

Figure 25. Differences in the water-table surface between the Death Valley version 3 (DV3) and Death Valley Regional 

Flow System version 2 (DVRFS.v2) hydrogeologic framework, and areas where the DVRFS.v2 hydrogeologic framework 

was modified, in the study area, Nevada and California. See figure 26 for cross section A–A’.
52 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Faults

Faults and caldera margins have been conceptualized 

as forming barriers or conduits to groundwater flow. Few 

geologic structures have sufficient hydraulic information 

to determine their behavior as a barrier or conduit. For 

example, lithologic data and aquifer-test results indicate that 

the Gravity fault (fig. 5) forms a hydraulic barrier (Dudley 

and Larson, 1976). The Gravity fault causes groundwater to 

move from underlying carbonate rocks into overlying basin 

fill and discharge at land surface from spring pools in the Ash 

Meadows discharge area (Laczniak and others, 1999). The 

northern part of the Timber Mountain caldera complex (fig. 5) 

is a transmissive feature, with transmissivities exceeding 

100,000 ft2/d (Garcia and others, 2017). The southern part of 

the Claim Canyon caldera (fig. 5) likely forms a hydraulic 

barrier, as indicated by the steepening of lateral hydraulic 

gradients between Timber Mountain and Yucca Mountain 

(IT Corporation, 1999; Fenelon and others, 2010, plate 3; 

Navarro-Intera, LLC, 2013). Attributing these hydraulic 

properties to caldera margins or adjacent rocks remains 

ambiguous.

Many faults are not hydraulically distinct from adjacent 

host rocks and have no direct hydraulic significance. 

Yucca fault (fig. 5) has been conceptualized as a conduit to 

groundwater flow in a local-scale CAU model of the carbonate 

aquifer beneath Yucca Flat (Navarro-Intera, LLC, 2013). 

However, drawdown analyses from multiple-well aquifer tests 

in wells ER-6-1-2 main (fig. 25; Jackson and Halford, 2019) 

and ER-4-1 m1 (fig. 25; Jackson, 2017) showed that pumping 

signals propagated across Yucca fault. The calibrated Yucca 

Flat CAU model of the carbonate aquifer also interpreted 

Yucca fault as an inconsequential hydraulic feature (NavarroIntera, LLC, 2013). In another example, the West Greeley 

fault in Pahute Mesa has been conceptualized as a conduit 

for groundwater flow and radionuclide transport (StollerNavarro Joint Venture, 2009). This interpretation was tested 

during analysis of a multiple-well aquifer test in well U-20 

WW (cased) (fig. 25), and results showed that estimated 

hydraulic conductivities of the fault were similar to those of 

the surrounding volcanic rocks, indicating that West Greeley 

fault is neither a conduit nor barrier to flow (Garcia and others, 

2011).

Faults were implemented explicitly by the offset of 

juxtaposed hydrogeologic units in the DV3 framework. 

Juxtaposition of a low-permeability hydrogeologic unit against 

a permeable unit causes a fault to function as a hydraulic 

barrier. Juxtaposition of permeable units along a fault allows 

for the movement of groundwater flow across the fault. 

Behavior of a fault as a barrier or conduit to groundwater flow 

was determined during calibration of the DV3 model by fitting 

simulated results to predevelopment water levels, water-level 

declines from pumping, and aquifer-test results.

Hydrogeologic Units

The DV3 framework was divided into ten hydrogeologic 

units (table 7) based on rock type, depth, and previously 

defined hydrogeologic units from the DVRFS.v2 project 

(table 6). Hydrogeologic units were consolidated initially for 

this study into four rock types (fig. 21). Two of the rock types 

contain thick sequences of carbonate and volcanic rocks, 

which were divided in the DV3 framework into shallow and 

deep intervals at 1,600 ft (500 m) below the water table based 

on analysis of hydraulic conductivity with depth (fig. 24). The 

shallow-deep concept (see section, “Hydraulic Conductivity 

and Depth”) was used as an alternative to a depth-decay 

model. Shallow carbonate rocks were further subdivided 

by separating Pennsylvanian (UCA, upper carbonate-rock 

aquifer) and fault-thrusted [(LCA_T1, lower carbonaterock aquifer (thrusted)] carbonate rocks, which have low 

permeabilities, from other carbonate rocks in the shallow 

interval so that expected transmissivity contrasts could 

be simulated (table 7). Deep volcanic rocks are relatively 

impermeable and were included in the low-permeability rock 

type (table 7). For example, transmissivity was 30 ft2/d around 

well UE-20f (4456-13686 ft) in deep volcanic rocks, or an 

average hydraulic conductivity of 0.003 ft/d (fig. 19).

Basin fill was differentiated into shallow and deep 

intervals to accommodate known hydrologic variability in 

the central Amargosa Desert and Pahrump Valley (table 7). 

Pronounced seasonal water-level fluctuations from seasonal 

irrigation pumping in the central Amargosa Desert suggest 

that less permeable sediments overlie the pumped interval. 

For example, water levels fluctuate seasonally and distinctly 

in wells AD-3a and AD-9 in response to seasonal irrigation, 

which requires a confining unit that is laterally extensive 

at distances greater than 1 mi from pumped wells. Refined 

lithologic classes for basin fill in the Amargosa Desert (Taylor 

and Sweetkind, 2014) were not considered when defining 

the extent of the less permeable sediments because hydraulic 

properties were predicted poorly (fig. 23). Instead, basin-fill 

sediments were defined based on lithologic well logs, locations 

of flowing wells, and water-level trends in wells. Continuity 

of fine-grained sediments that confine deeper, coarse-grained 

basin fill in Pahrump Valley was indicated by historically 

flowing wells near Bennetts Spring and 4 mi south-southwest 

of Manse Spring (Waring, 1921). Wells such as H & H, which 

was capped and had a water level of 57 ft above land surface 

in 1948, extended the area of confinement at least 4 mi north 

of Bennetts Spring (Harrill, 1986).
Predevelopment Groundwater Flow 53

Table 7. Hydrogeologic units in the Death Valley version 3 model (DV3) hydrogeologic framework that were defined by rock type, 

depth, and previously defined hydrogeologic units from the Death Valley Regional Flow System version 2 model (DVRFS.v2) project, 

Nevada and California.

[Source: Belcher and others (2017). Description: AFFCR, Alkali Flat–Furnace Creek Ranch; AM, Ash Meadows; PDVS, Pahrump to Death Valley South; 

PMOV, Pahute Mesa–Oasis Valley. DVRFS.v2 hydrogeologic unit: BRU, Belted Range unit; CFBCU, Crater Flat–Bullfrog confining unit; CFPPA, Crater 

Flat–Prow Pass aquifer; CFTA, Crater Flat–Tram aquifer; CHVU, Calico Hills volcanic-rock unit; ICU, Intrusive-rock confining unit; LA, Limestone aquifer; LCA, Lower carbonate-rock aquifer; LCA_T1, Lower carbonate-rock aquifer (thrusted); LCCU, Lower clastic-rock confining unit; LCCU_T1, Lower 

clastic-rock confining unit (thrusted); LFU, Lava-flow unit; OAA, Older alluvial aquifer; OACU, Older alluvial confining unit; OVU, Older volcanic-rock unit; 

PVA, Paintbrush volcanic-rock aquifer; SCU, Sedimentary-rock confining unit; TMVA, Thirsty Canyon-Timber Mountain volcanic-rock aquifer; UCA, Upper 

carbonate-rock aquifer; UCCU, Upper clastic-rock confining unit; VSU upper, Upper volcanic-sedimentary rock unit; VSU lower, Lower volcanic-sedimentary 

rock unit; WVU, Wahmonie volcanic-rock unit; XCU, Crystalline-rock confining unit; YAA, Younger alluvial aquifer; YACU, Younger alluvial confining unit; 

YVU, Younger volcanic-rock unit]

Rock type DV3 hydrogeologic unit Description DVRFS.v2 

hydrogeologic unit

Carbonate rocks Shallow, low-permeability carbonate 

rocks

Occur primarily beneath Rainier Mesa, western Yucca Flat, Specter Range, 

and Sheep Range.

UCA, LCA_T1

Shallow carbonate 

rocks

Regionally extensive in the AM basin. Spans from Pahrump Valley to the 

Amargosa River in the PDVS basin and occurs in the southern Funeral 

Mountains in the AFFCR basin.

LCA_T1, LCA

Deep carbonate 

rocks

Regionally extensive in the AM basin. Spans from Pahrump Valley to the 

Amargosa River in the PDVS basin. Occurs beneath Shoshone Mountain, 

Yucca Mountain, Jackass Flats, Amargosa Desert, and the Funeral Mountains 

in the AFFCR basin.

LCA_T1, LCA

Volcanic rocks Shallow volcanic 

rocks

Extends north-south from Pahute Mesa and Black Mountain to Yucca Mountain and Jackass Flats, and extends west-east from Oasis Valley to Rainier 

Mesa in the PMOV and AFFCR basins. Forms localized units beneath Yucca 

Flat, Frenchman Flat, and Emigrant Valley in the AM basin.

LFU, YVU, TMVA, PVA, 

CHVU, WVU, CFPPA, 

CFBCU, CFTA, BRU

Basin fill Shallow basin fill Upper 200 ft of saturated basin fill beneath valleys, including the Amargosa 

Desert, Death Valley, Pahrump Valley, Oasis Valley, Emigrant Valley, Yucca 

Flat, and Frenchman Flat.

YAA, YACU, OAA, OACU, 

LA, VSU upper

Confining unit in 

Pahrump Valley

Saturated basin fill between 200 and 400 ft below the water table in Pahrump 

Valley. Basin fill divided into three units, where this is the intermediate unit, 

which was used to provide hydraulic separation between shallow (unconfined) basin fill and deep (confined) basin fill.

YAA, YACU, OAA, OACU, 

LA, VSU upper

Deep basin fill Remainder of saturated basin fill beneath valleys, including the Amargosa 

Desert, Death Valley, Pahrump Valley, Oasis Valley, Emigrant Valley, Yucca 

Flat, and Frenchman Flat.

YAA, YACU, OAA, OACU, 

LA, VSU upper

Volcanic-Sedimentary 

rocks

Volcanic-sedimentary rocksShallow volcanic-sedimentary rocks. Rocks are saturated in northern PMOV

basin from the Cactus Range to Kawich Valley. These rocks form the lowpermeability “tuff pile” beneath Rainier Mesa, Yucca Flat, and Frenchman 

Flat, and extend beneath Emigrant Valley in the AM basin. Rocks extend 

from Amargosa Desert to Greenwater Range in AFFCR basin, and occur 

beneath Pahrump Valley and Sperry Hills in PDVS basin.

OVU, VSU upper

Low-permeability rocks Deep volcanic 

rocks

Deep volcanic rocks and volcanic-sedimentary rocks. Regionally extensive 

throughout PMOV basin. Occur beneath Yucca Mountain, Amargosa Desert, 

Death Valley, and Eagle Mountain in AFFCR basin. Saturated rocks are 

localized beneath Emigrant Valley in the AM basin, and localized beneath 

Pahrump Valley and Sperry Hills in the PDVS basin.

TMVA, PVA, CHVU, WVU, 

CFPPA, CFBCU, CFTA, BRU, 

OVU, VSU lower

Granitic and siliciclastic rocksClastic sediments (and their metamorphosed equivalents), and granite, 

granodiorite, quartz monzonite, and tonalite in stocks, dikes, sills, and 

plutons. Rocks extend from the Resting Spring Range and California Valley 

to Death Valley in the PDVS basin, and between Pahrump Valley and the Ash 

Meadows discharge area. Rocks occur beneath the Greenwater Range, Black 

Mountains, and northern Funeral Mountains in the AFFCR basin. Rocks 

are saturated to the west, north, and east of Yucca Flat in the Eleana Range, 

Climax Stock, and Halfpint Range, respectively.

ICU, SCU, UCCU, LCCU_T1, 

LCCU, XCU
54 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Deep basin fill mostly was differentiated from shallow 

basin fill in the DVRFS.v2 framework and classified as 

lower volcanic-sedimentary rock unit (VSU lower; table 3). 

These deep, volcanic-sedimentary rocks are clay-rich and 

cemented, and are otherwise impermeable (Sweetkind and 

others, 2010). For example, well Inyo-BLM 2 is open to deep, 

volcanic-sedimentary rocks that have a hydraulic conductivity 

of 3 × 10-6 ft/d (fig. 19). Greater cementation, occurrence 

of evaporites, and other less-permeable basin fill have been 

observed at depths greater than 1,600 ft below the water table 

elsewhere in the Great Basin (Halford and Plume, 2011). The 

VSU lower was classified as part of the low-permeability rock 

type in the DV3 framework (table 7).

Shallow volcanic-sedimentary rocks were retained as a 

unique hydrogeologic unit in the DV3 framework because 

hydraulic isolation was needed between overlying and 

underlying aquifers and because rocks in some basins and 

ranges were undifferentiated. Volcanic-sedimentary rocks 

consist of tuffs; lavas; alluvium; colluvium; and eolian, 

fluvial, and lacustrine deposits (Sweetkind and others, 2010). 

Volcanic-sedimentary rocks function as confining units that 

hydraulically isolate basin fill from underlying carbonate rocks 

in CP basin (fig. 25), Frenchman Flat, and Yucca Flat. Basin 

fill in Gold Flat and Kawich Valley and consolidated rocks in 

the surrounding mountain ranges mostly were undifferentiated 

because these rocks were grouped into volcanic-sedimentary 

unit. Expected differences between transmissivity of basin 

fill and mountain ranges were addressed when hydraulic 

conductivities were distributed in groundwater models during 

calibration.

The intermediate hydrogeologic framework grid, which 

consisted of uniform 164-ft-thick (50-m-thick) layers, was 

reduced to 5 layers for the DV3 hydrogeologic framework. 

Hydrogeologic units from DV3 were substituted for 

previously defined hydrogeologic units from DVRFS.v2 

(table 7). Layer contacts were assigned nominally at depths of 

164, 328, 820, and 1,640 ft (50, 100, 250, and 500 m) below 

the water table. An exception occurred if lithologic well data 

provided sufficient control to align the contacts between 

layers at the contacts between hydrogeologic units (fig. 26). 

Sufficient hydrologic control was limited to an area in the 

NNSS that was bounded by Yucca Mountain, Rainier Mesa, 

and Yucca Flat (fig. 25). Layer contacts were nominal depths 

below the water table outside the limited area, which was 

sufficient to preserve contacts between hydrogeologic units 

because units typically thinned or thickened by less than 330 ft 

(100 m). The thickest hydrogeologic unit was assigned where 

multiple hydrogeologic units intersected a cell. This primarily 

occurred in the deepest layer because average thicknesses 

exceeded 4,000 ft.

Revisions from Underground Test Area Projects 

Hydrogeologic frameworks for Frenchman Flat, Yucca 

Flat–Climax Mine, Rainier Mesa–Shoshone Mountain, and 

Pahute Mesa CAUs (fig. 27) were created and revised to 

support the UGTA project. Hydrogeologic frameworks for 

CAUs were developed after the DVRFS.v1 hydrogeologic 

framework was developed (Belcher, 2004; Belcher and 

Sweetkind, 2010). Hydrogeologic units beneath Frenchman 

Flat (Bechtel Nevada, 2005a), Yucca Flat (Bechtel Nevada, 

2006; Fenelon and others, 2012), and Rainier Mesa–

Shoshone Mountain (National Security Technologies, LLC, 

2007; Fenelon and others, 2008) were revised in the DV3 

framework. Revisions were warranted because details were 

missing in the DVRFS.v2 framework, such as aquifers that are 

known to be isolated where volcanic tuffs intervened between 

underlying carbonate rocks and overlying basin fill or volcanic 

rocks.

Revisions to hydrogeologic frameworks for CAUs were 

informed by additional data collection through the drilling of 

wells. Geologic and hydrologic uncertainties were reduced as 

a result of the UGTA project; 34 new boreholes were drilled 

and 119 new wells were completed during 2000–16, with 

most boreholes having multiple completions referred to as 

wells. Features such as Frenchman Flat basin were revised 

extensively because data from wells superseded surface 

mapping and geophysical inferences (Bechtel Nevada, 2005a). 

Well ER-5-3-2 (fig. 27) drilled through 4,000 ft of saturated 

basin fill before encountering carbonate rocks (Bechtel 

Nevada, 2005b), in contrast to the DVRFS.v2 framework, 

which interprets the basin fill contact with carbonate rocks as 

occurring above the water table. The edge of Frenchman Flat 

basin, where saturated basin fill occurs, was moved 3 mi north 

because of additional well control (fig. 27). Carbonate rocks 

were expected 6,000 ft below land surface in well ER-5-4-2

but were not encountered after drilling 7,000 ft below land 

surface (Bechtel Nevada, 2005c). Data from wells quintupled 

the volume of saturated basin fill in Frenchman Flat basin 

from the DVRFS.v2 framework to the DV3 framework.

Revisions to the DV3 framework were hydraulically 

important in northern Yucca Flat, and for local basin-fill 

aquifers and adjacent volcanic-sedimentary rocks in the 

eastern NNSS. Quartzite Ridge and Climax Mine, upgradient 

of wells WW-2 (3422 ft) and ER-8-1 (recompleted), are 

mapped as low-permeability rocks (DV3 framework) rather 

than as carbonate rocks (DVRFS.v2 framework), which is 

consistent with surface geology, well logs, and elevated water 

levels (fig. 28; Winograd and Thordarson, 1975; Fenelon and 

others, 2012). Better mapping extents and thicknesses of basin 

fill and volcanic rocks in Yucca Flat improved representation 

of local aquifers (fig. 28). Local basin-fill aquifers in Yucca 

Flat supplied pumping wells WW-A and WW-3 with 2,700 

and 620 acre-ft, respectively, from 1952–1988 (fig. 28; Elliott 

and Moreo, 2011). Revising these local basin-fill aquifers 

improved simulation of water-level declines in pumping 

wells WW-A and WW-3 because these basin-fill aquifers were 

absent in the DVRFS.v2 framework (fig. 28) and incorrectly 

simulating pumping from volcanic rocks of limited extent 

imposes an artificial hydraulic barrier, resulting in larger 

simulated water-level declines in wells WW-A and WW-3 than 

otherwise occurs based on water-level data.
Predevelopment Groundwater Flow 55

sac19-4233_fig 26

Land surface

Water table

Pahute 

Mesa

Rainier 

Mesa Yucca 

Flat

Emigrant 

Valley

Pahranagat 

Range

Pahute 

Mesa

Rainier 

Mesa

Yucca 

Flat Emigrant 

Valley

Pahranagat 

Range

Lowpermeability 

LCA

OVU

OVU

OVU

OVU

OVU

ICU

ICU

LCCU

UCCU

LCCU

BRU

CFBCU

CHVU

VSU 

lower

YAA

LCA

UCA

VSU upper

TMVA PVA

BRU

PVA

CHVU

LCA

VSU 

lower

CARB–D

CARB–S

CCU

VSU

VOLC–D CARB–D

VOLC–S

CARB–S CCU

CARB–Low T BF

0 20 MILES

0 10

10

20 KILOMETERS

Altitude above National Geodetic Vertical Datum of 1929, in feet Altitude above National Geodetic Vertical Datum of 1929, in feet

Altitude above National Geodetic Vertical Datum of 1929, in meters

2,600

2,000

0

-1,000

1,000

0

0

Intermediate grid of DVRFS.v2 framework

Simplified 5-layer grid in DV3 framework

8,000

6,000

4,000

-4,000

2,000

-2,000

FEET

A

WEST

METERS

A'

EAST

Altitude above National Geodetic Vertical Datum of 1929, in meters

2,000

0

-1,000

1,000

METERS

A'

EAST

6,000

4,000

-4,000

2,000

-2,000

FEET

A

WEST

YAA Younger alluvial aquifer

TMVA Thirsty Canyon–Timber Mountain 

volcanic-rock aquifer

PVA Paintbrush volcanic-rock aquifer

CHVU Calico Hills volcanic-rock unit

CFBCU Crater Flat–Bullfrog confining unit

BRU Belted Range unit

OVU Older volcanic-rock unit

VSU upper Upper volcanic-sedimentary rock unit

VSU lower Lower volcanic-sedimentary rock unit

ICU Intrusive-rock confining unit

UCA Upper carbonate-rock aquifer

UCCU Upper clastic-rock confining unit

LCA Lower carbonate-rock aquifer

LCCU Lower clastic-rock confining unit

Hydrogeologic units in DVRFS.v2 framework model

EXPLANATION

Hydrogeologic units in DV3 framework model

BF Shallow basin fill

VOLC–S Shallow volcanic rocks

VOLC–D Deep volcanic rocks

VSU Volcanic-sedimentary rocks

CARB–Low T Shallow, low-permeability carbonate rocks

CARB–S Shallow carbonate rocks

CARB–D Deep carbonate rocks

CCU Granitic and siliciclastic rocks

DV3 hydrogeologic framework model layer top

Water table (top of DV3 hydrogeologic framework model)

Figure 26. Example cross sections through intermediate grid of Death Valley Regional Flow System 

version 2 (DVRFS.v2) (Belcher and others, 2017; top cross section), and Death Valley version 3 (DV3; bottom 

cross section) hydrogeologic framework models, Nevada and California. Trace of cross section A–A’ is 

shown in figure 25.
56 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 27

95

95

373

190

127

Amargosa Mercury

Valley

Indian

Springs

Beatty

Furnace

Creek

ER-8-1 (recompleted)

ER-5-3-2

ER-5-4-2

TW-F

WW-C-1

WW-3

ER-7-1

TW-1

UE-19h

PM-2

ER-EC-4

ER-EC-7

WW-2 (3422 ft)

WW-A

WW-4

WW-4A

ER-20-11

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO.

CALIFORNIA

NEVADA

Pahute Mesa

Gold Flat

Oasis Valley

Belted Range

Kawich Range

Funeral Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Specter Range

Halfpint Range

Spotted Range

Eleana Range

Kawich

Valley

Yucca

Flat

Climax

Mine Quartzite

Ridge

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Franklin

Lake

Pahrump

Valley

Groom

Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Devils 

Hole

EXPLANATION

Extent of Frenchman Flat 

basin at water table in 

DVRFS.v2 hydrogeologic 

framework model

Area where carbonate rocks 

at water table were 

revised between DVRFS.v2 

and DV3 hydrogeologic 

framework models 

—Carbonate rocks revised 

to volcanic rocks, basin fill, 

or low-permeability rocks 

based on lithologic well 

data

Extent of hydrogeologic 

framework model

Frenchman Flat (Bechtel 

Nevada, 2005a)

Yucca Flat-Climax Mine 

(Bechtel Nevada, 2006)

Pahute Mesa (Bechtel 

Nevada, 2002)

Rainier Mesa–Shoshone 

Mountain (National 

Security Technologies, 

LLC, 2007)

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations area

WW-A

0 10 MILES

0 10 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°

37°

36°

30'

Map

area

Study 

area

Figure 27. Extents of hydrogeologic framework models for Frenchman Flat, Yucca Flat–Climax Mine, Rainier Mesa–

Shoshone Mountain, and Pahute Mesa corrective action units; extent of Frenchman Flat basin in Death Valley Regional 

Flow System version 2 model (DVRFS.v2) hydrogeologic framework; and areas where carbonate rocks at water table 

in DVRFS.v2 were revised to volcanic rocks, basin fill, or low-permeability rocks in Death Valley version 3 model (DV3) 

hydrogeologic framework based on lithologic well data, Nevada and California.
Predevelopment Groundwater Flow 57

sac19-4233_fig 28

Eleana Range

Halfpint Range

 Flat

Yucca

Climax

Mine Quartzite

Ridge

Eleana Range

Halfpint Range

 Flat

Yucca

Climax

Mine Quartzite

Ridge

Eleana Range

Halfpint Range

 Flat

Yucca

Climax

Mine Quartzite

Ridge

WW-C-1

WW-A

ER-7-1

WW-3

ER-8-1 (recompleted)

WW-2 (3422 ft)

ER-6-2

UE-16d WW

WW-C-1

WW-A

ER-7-1

WW-3

ER-8-1 (recompleted)

WW-2 (3422 ft)

ER-6-2

UE-16d WW

WW-C-1

WW-A

ER-7-1

WW-3

ER-8-1 (recompleted)

WW-2 (3422 ft)

ER-6-2

UE-16d WW

0 5 MILES

0 5 KILOMETERS

Shallow basin fill

Shallow volcanic rocks

Volcanic-sedimentary rocks

Shallow carbonate rocks

Shallow, low-permeability 

carbonate rocks

Granitic and siliciclastic rocks

Well and identifier

EXPLANATION

Nevada National Security Site 

boundary—Internal operations 

areas dashed

Hydrogeologic units

ER-7-1

Universal Transverse Mercator Projection, Zone 11, North American 

Datum of 1983.

DVRFS.v2 framework

Fenelon and others (2012)

DV3 framework

116°10' 116°

37°

10'

37°

37°

10'

37°

116°10' 116°

Figure 28. Hydrogeologic units in Death Valley Regional Flow System version 2 model (DVRFS.v2; top left 

map), Death Valley version 3 model (DV3; top right map), and Fenelon and others (2012) (bottom map), at 

the water table beneath Yucca Flat, Nevada.
58 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Extents of permeable rocks in CP basin and surrounding 

low-permeability rocks (fig. 27) were revised for similar 

reasons because CP basin is isolated hydraulically (Fenelon 

and others, 2010, p. 21). Water levels in well WW-4, in 

CP basin (fig. 27), declined more than 10 ft in response to 

pumping 7,300 acre-ft of water from wells WW-4 and WW-4A

during 1981–2017. The transmissivity of basin fill at well 

WW-4A is 27,000 ft2

/d, indicating that water levels in well 

WW-4 would have declined less than 1 ft if CP basin were not 

isolated.

Hydrogeologic frameworks for the Pahute Mesa CAU 

were not incorporated in the DV3 framework because Pahute 

Mesa consists primarily of thick sequences of volcanic 

rocks (Fenelon and others, 2016). Uniqueness of hydraulic 

variability between hydrogeologic units from the original and 

a revised framework for Pahute Mesa CAU (Bechtel Nevada, 

2002; Garcia and others, 2017) was tested by simultaneously 

interpreting 8–16 interfering MWATs. Hydraulic-conductivity 

estimates varied more within hydrogeologic units than 

between hydrogeologic units (Belcher and others, 2002; 

Mirus and others, 2016; Garcia and others, 2017). Another 

interpretation using a single MWAT at well ER-20-11 (fig. 27) 

reached a similar conclusion: “The hydraulic conductivities 

of the aquifers, confining units, and composite units show 

considerable overlap in their estimated values with no 

discernible trend among the different rock types,” (Navarro, 

2016a, p. 5-35).

Hydraulically Mandated Features

In the DV3 framework, discharge areas were connected 

to upgradient aquifers by changing shallow hydrogeologic 

units in the Furnace Creek area, Lower Amargosa area, and 

Saratoga Spring area. Potential localized hydraulic barriers 

were introduced in the Ash Meadows discharge area based 

on hydraulic data and attenuated responses to local pumping. 

Revisions to the DV3 framework, from the DVRFS.v2 

framework, were warranted based on geologic evidence and 

hydrologic data.

A localized hydraulic barrier was introduced into shallow 

carbonate rocks in the Ash Meadows discharge area north of 

Fairbanks Spring (fig. 7) because a steep horizontal hydraulic 

gradient exists. Water-level altitudes declined from 2,361 ft 

in well GF-2B deep (AM-11) to 2,250 ft at Fairbanks Spring

over a distance of 3,500 ft, a gradient of 160 ft/mi. Hydraulic 

gradients north of well GF-2B deep (AM-11) are less than 

2 ft/mi and transmissivities exceed 100,000 ft2

/d. This high 

hydraulic gradient can be explained by a low-permeability 

feature, such as a fault, north of Fairbanks Spring that offsets 

thin permeable horizons in shallow carbonate rocks (Dudley 

and Larson, 1976, p. 49). Groundwater would need to flow 

through shallow carbonate rocks south of the low-permeability 

feature to discharge from Fairbanks Spring. The location and 

orientation of the low-permeability feature were interpreted 

from a fault map of the Ash Meadows discharage area (Dudley 

and Larson, 1976).

Another potential localized hydraulic barrier is suggested 

by attenuated responses to injection in Devils Hole Well (AM5), which is 900 ft east of Devils Hole (fig. 7). About 1,700 

acre-ft of water was injected in Devils Hole Well (AM-5)

from July 1973 to August 1977 at rates of 400 gal/min, with 

the intent of mitigating water-level declines in Devils Hole

(Larson, 1974a, 1974b, 1975; Carson, 1979). A detectable 

rise of 1 ft would be expected in Devils Hole if transmissivity 

and specific yield reasonably averaged 50,000 ft2

/d and 0.02, 

respectively, around Devils Hole Well (AM-5). No discernable 

response was observed in Devils Hole (Dudley and Larson, 

1976), which suggests a low-permeability feature exists in the 

shallow carbonate rocks between Devils Hole Well (AM-5)

and Devils Hole. A fault was postulated and introduced in 

the shallow carbonate rocks (fig. 7) along previously mapped 

lineaments and faults (Dudley and Larson, 1976, p. 49).

Furnace Creek Wash was revised in the DV3 framework 

for consistency with the conceptualization of discharge from 

the Furnace Creek area (fig. 9). Furnace Creek Wash consists 

of basin-fill deposits based on well logs but was mapped as 

undifferentiated volcanic-sedimentary rocks in the DVRFS.

v2 framework. These undifferentiated volcanic-sedimentary 

rocks were changed to basin fill in the DV3 framework so 

that groundwater flow could be simulated through Furnace 

Creek Wash between upgradient Travertine Springs and 

downgradient alluvial fan on the Death Valley floor (fig. 9).

Low-permeability rocks formed an unwarranted 

hydraulic barrier in the Lower Amargosa area. The DVRFS.

v2 framework mapped low-permeability rocks at the water 

table between the Nopah Range and Amargosa River, which 

impeded the movement of groundwater downgradient of 

Chicago Valley to discharge areas near Tecopa (fig. 12). Lowpermeability rocks between the Nopah Range and Amargosa 

River were remapped, based on geologic interpretations, as 

carbonate rocks and basin fill, which was needed to allow 

westward flow to be simulated to Resting Spring and Tecopa 

(fig. 12). Basin fill added near Tecopa primarily represents 

saturated China Ranch beds in the area bounded by Resting 

Spring, Tecopa, and West Willow Spring.

Spatial distribution of discharge in the Lower Amargosa 

area differs between the DVRFS.v2 project and this 

investigation because low-permeability rocks were remapped 

in the DV3 framework. Discharges were simulated in the 

DVRFS.v2 project (Faunt, Sweetkind, and Belcher, 2010) 

at locations where ET units were mapped by Laczniak and 

others (2001). However, more than 30 percent of the ET 

units occurred from rocks mapped as impermeable in the 

DVRFS.v2 hydrogeologic framework. Mapped ET in these 

instances should overlie basin fill in the Amargosa River 

downstream of Tecopa and China Ranch Wash (fig. 12). Errors 

occurred in the DVRFS.v2 hydrogeologic framework because 

basin-fill deposits in these channels have limited extents 

and are bounded by impermeable rocks. Shallow geology 

of the Tecopa/California Valley area was changed in this 

investigation so that discharges from ET units are simulated 

from basin-fill deposits (fig. 12).
Groundwater Development 59

The Amargosa River channel was revised in the DV3 

framework for consistency with the conceptualization of 

flow in the Saratoga Spring area. The Amargosa River 

channel between Dumont Dunes and the Saratoga Spring 

area (fig. 14) consists of basin fill; however, the DVRFS.v2 

framework mapped the channel as low-permeability rocks. 

Incorrectly mapped low-permeability rocks at the water table 

were remapped as basin fill between Dumont Dunes and the 

Saratoga Spring area. Basin fill is required upgradient of 

Saratoga Pools for the simulation of flood infiltration and base 

flow downstream of the Amargosa River at Dumont Dunes, 

California (USGS streamgage 10251375).

Groundwater Development

Groundwater development entails pumping wells and 

nonpumping flowing wells, which affect groundwater flow as 

water is withdrawn from the aquifer system. When a pump is 

first turned on, water is supplied from storage. Eventually, if 

pumping continues for sufficient time, some of the pumped 

water will be supplied by natural discharge. Sources of water 

to wells were summarized originally by Theis (1940, p. 10) 

as follows: “All water discharged by wells is balanced by a 

loss of water somewhere. This loss is always to some extent 

and in many cases largely from storage in the aquifer. Some 

groundwater is always mined,” and “After sufficient time has 

elapsed...further discharge by wells will be made up in part by 

a diminution in the natural discharge.” Decreased discharge to 

springs, wetlands, and phreatophytes as a result of pumping is 

termed capture (Konikow and Leake, 2014).

Water-level declines and capture that result from 

groundwater development are affected by the rate and 

volume pumped, distance to pumping centers, distance to 

discharge areas, and aquifer hydraulic properties. In pumped 

wells, water levels decline proportionally with increasing 

pumping rates. Pumping centers where large volumes of 

water are withdrawn have greater magnitudes and extents 

of water-level declines compared to pumping centers where 

small volumes are withdrawn. Pumping centers distant 

from discharge areas have greater magnitudes and extents 

of water-level declines compared to pumping centers within 

discharge areas. Water-level declines and capture also are 

affected by hydraulic properties of the rocks. The ratio of 

transmissivity to storativity (specific yield plus specific storage 

times thickness), known as hydraulic diffusivity, controls the 

magnitude and lateral extent of water-level declines from 

groundwater development. Water-level declines propagate 

farther and faster from pumping centers as hydraulic 

diffusivities increase.

Groundwater development in the study area principally 

has removed water from storage because pumping has 

been relatively distant from discharge areas (fig. 29). Large 

groundwater withdrawals primarily have occurred in the 

central Amargosa Desert and Pahrump Valley, but discharge 

areas greater than 10 mi from these pumping centers have not 

been affected measurably. For example, local pumping wells 

in the Ash Meadows discharge area affected spring discharges 

within 5 mi during 1968–80 (Dudley and Larson, 1976), but 

effects of distant pumping from the central Amargosa Desert 

were not discernable. About one-half of the discharge in Ash 

Meadows is from Crystal Pool, Fairbanks Spring, and Big 

Spring, which averaged 12.7 ft3/s (9,200 acre-ft/yr) prior to 

1969 (Dudley and Larson, 1976). Combined discharge from 

these springs averaged 12.6 ft3/s (9,100 acre-ft/yr) from 

2008–2017 (U.S. Geological Survey, 2018a), which is no 

change relative to measurement standard deviations of 0.1–0.4 

ft3/s (100–300 acre-ft/yr).

Predicted effects of groundwater development depend 

on estimated pumping rates, water-level changes, and capture 

(Bredehoeft, 2002). Uncertainty in these quantities propagates 

into estimated distributions of transmissivity and storativity. 

Estimates of pumping prior to 1950 are uncertain because 

most groundwater was withdrawn from nonpumped flowing 

wells where data are sparse. Long-term (>50 years) waterlevel data are limited in the central Amargosa Desert and 

Pahrump Valley despite long pumping histories. For example, 

groundwater development has occurred in Pahrump Valley 

from 1913 to present (2018); however, only five wells in 

Pahrump Valley have long-term (1950–2018) water-level 

measurements and no wells provide information about 

water-level declines from 1913–1950. Based on comparison 

of historical and current spring discharges, 15–20 percent of 

predevelopment discharge has been captured in response to 

more than 100 years of groundwater development in the study 

area.

Data Compilation

Groundwater-withdrawal data and return-flow estimates 

used in this report are provided in a supplemental data release 

(Jackson and Halford, 2020). Groundwater-withdrawal data 

from 1913 to 2010 were compiled from Elliott and Moreo 

(2018), which is an updated database that supersedes previous 

databases (Moreo and others, 2003; Moreo and Justet, 2008). 

In this report, more-recent groundwater withdrawals were 

estimated by projecting 2010 pumping rates through 2018.

Groundwater-withdrawal data used in this report 

incorporate minor revisions to Elliott and Moreo (2018). For 

example, in the Elliott and Moreo (2018) database, pumping 

for dewatering the Barrick-Bullfrog mine incorrectly was 

attributed to wells 3 and 4 mi south of the Barrick-Bullfrog 

pit. This pumpage was assigned to temporary dewatering wells 

within 1,000 ft of the north edge of the Barrick-Bullfrog pit in 

this study. Injection in Devils Hole Well (AM-5) of about 1,700 

acre-ft from July 1973 to August 1977 (Larson, 1974a, 1974b, 

1975; Carson, 1979) was not inventoried in Elliott and Moreo 

(2018) and was added for this study.
60 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 29

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Rainier Mine

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Emigrant 

Valley

Devils Hole

Ash Meadows 

discharge area

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Observation well or site

Maximum drawdown extent 

from pumping—based on 

a minimum water-level 

decline of 0.1 ft per decade 

in wells and known 

hydraulic barriers

Hydraulic barrier—area of 

low-permeability rock at 

the water table, interpreted 

from the DV3 hydrogeologic framework model

Areas of potential groundwater capture by 

 pumping

Discharge from springs

Discharge from phreatophytes

Pumping well—annual 

withdrawals in acre-feet 

per year

Less than or equal to 100

Greater than 100

EXPLANATION

Groundwater basin 

boundary modified 

from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas Dumont

Dunes

Figure 29. Pumping wells, areas affected by groundwater development, and hydraulic barriers, in the study area, 

Nevada and California. DV3, Death Valley version 3.
Groundwater Development 61

Pumping and Return Flow

Pumping in the study area has been inventoried and 

estimated by water-use type because water-use type is 

correlated strongly with measurement uncertainty (Moreo and 

others, 2003). This is because pumping is estimated differently 

for irrigation, domestic, and metered water-use groups. 

Irrigation pumping was estimated by multiplying irrigated 

acreage by annual crop application rates that averaged 7 ft/yr 

(Moreo and Justet, 2008). Domestic pumping was estimated 

by multiplying the number of wells by an annual pumping 

volume of 0.7 acre-ft for each well (Moreo and others, 2003). 

Pumping estimates for domestic and irrigation water uses have 

an uncertainty of about 20 percent (Moreo and Justet, 2008). 

Metered pumping includes commercial, industrial, mining, 

and public-supply wells, and is known within 10 percent. Most 

metered pumping is for public supply, which includes NNSS 

and Department of Defense supply wells (Moreo and others, 

2003).

Total groundwater withdrawals from irrigation, domestic, 

and metered water use were compared to predevelopment 

discharge estimates for each groundwater basin (fig. 30). 

AFFCR and Ash Meadows groundwater basins were combined 

because pumping from either basin can affect predevelopment 

discharges in both basins (see section, “Groundwater-Basin 

Boundary Uncertainty”). Annual groundwater withdrawals 

exceeded predevelopment discharge in the PDVS groundwater 

basin from 1952–2002 (fig. 30). As of 2018, groundwater 

withdrawals have never exceeded predevelopment discharges 

in the AFFCR, Ash Meadows, or PMOV groundwater basins 

(fig. 30).

Groundwater withdrawals primarily have occurred in the 

AFFCR and PDVS groundwater basins where, historically, 

withdrawals principally supplied irrigation (fig. 30). 

Groundwater withdrawals in the AFFCR groundwater basin 

have increased from 1950 to present (2018) where, on average, 

withdrawals for irrigation account for about 90 percent of 

total withdrawals. Maximum groundwater withdrawals in the 

PDVS groundwater basin occurred between 1960 and 2000, 

when withdrawals for irrigation averaged 30,100 acre-ft/yr and 

total withdrawals averaged 32,600 acre-ft/yr.

Substantial pumping from domestic wells was limited 

to Pahrump Valley in the PDVS groundwater basin (fig. 30). 

Pumping from domestic wells in the PDVS groundwater basin 

was minor prior to 1970 and totaled 8,100 acre-ft/yr during 

2010. Domestic pumping in Pahrump Valley accounted for 95 

percent of all pumping from domestic wells in the study area 

during 2010.

Most metered pumping in the study area was for 

public supply, with episodic periods when mining usage 

was prevalent. About 60 percent of metered pumping in the 

study area supported activities at the NNSS between 1960 

and 1980 (Moreo and Justet, 2008). Pumping for NNSS 

activities occurred in the AFFCR, Ash Meadows, and PMOV 

groundwater basins (fig. 30). Pumping at the NNSS declined 

after 1990 and averaged 800 acre-ft/yr from 2000–2010 

(Elliott and Moreo, 2011). Pumping for mine dewatering 

south of Bullfrog Hills and in Crater Flat averaged 1,800 

acre-ft/ yr from 1984–2004 (Elliott and Moreo, 2018), where 

this pumping occurred in the AFFCR and PMOV groundwater 

basins. Ninety percent of metered pumping in the AFFCR 

and Ash Meadows groundwater basins during 2010 was 

for commercial and public supply (fig. 30). Public supply 

accounted for greater than 90 percent of metered pumping in 

the PDVS groundwater basin between 1980 and 2010 (Moreo 

and Justet, 2008).

A fraction of pumped groundwater infiltrates below the 

root zone and recharges the saturated groundwater system 

as return flow (Harrill, 1986). Return flow is computed as a 

fraction of total groundwater withdrawals, where fractions 

differed between metered, domestic, and irrigation water use 

(table 8). Of the three water-use components, return flows 

from irrigation wells were the smallest decimal fraction 

(0.17) of annual pumping volumes (Stonestrom and others, 

2007). However, return flows from irrigation wells accounted 

for 60 percent of total return-flow volumes in the study area 

from 1913–2010 (fig. 30). Return flows from metered wells 

averaged one-half of annual pumping volumes (Harrill, 1986). 

Moreo and Justet (2008) estimated an annual pumping volume 

of 0.7 acre-ft per domestic well, whereas the revised estimate 

of annual net consumptive use is 0.5 acre-ft/yr (Geter, 2015, 

p. 2). Return flow for each domestic well was 0.2 acre-ft/yr, 

which was computed from the product of 0.7 acre-ft/yr and 

0.29 (table 8). A domestic well return-flow rate of 0.2 acre-ft/

yr is the difference between the revised net consumptive-use 

(0.5 acre-ft/yr) and the previously published pumping estimate 

(0.7 acre-ft/yr). Annual return-flow volumes from domestic 

wells exceeded 2,000 acre-ft after 2005 in the study area. 

Return flow for mining was reported as injection to wells or 

infiltration in basins (Moreo and Justet, 2008).
62 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig30

Ash Meadows

irrigation 

Alkali Flat-Furnace

Creek Ranch

irrigation

0

10

20

30

A. Alkali Flat-Furnace Creek Ranch and Ash Meadows 

0

10

20

30

40

50

1910 1920 1930 1940 1950 1960

Year

1970 1980 1990 2000 2010 2020

C. Pahrump to Death Valley South

0

10

B. Pahute Mesa-Oasis Valley

Groundwater withdrawals, in thousands of acre-feet per year

Projected Projected

Irrigation

Metered

Domestic

Return flow

Predevelopment 

discharge

EXPLANATION

Figure 30. Total annual groundwater withdrawals by water-use type, return flow, and predevelopment 

discharge by groundwater basin, in the study area, Nevada and California, 1910–2010, with withdrawal 

estimates from 2010 projected through 2018. Irrigation water use is differentiated between Alkali Flat–

Furnace Creek Ranch and Ash Meadows groundwater basins, whereas metered and domestic use are 

combined totals.
Groundwater Development 63

Table 8. Fraction of return flow and velocity through unsaturated zone, in the study area, Nevada and California.

[Water-use group: Metered includes commercial, industrial, mining, and public-supply wells]

Water-use group Return flow fraction Pore velocity

(feet per year) Reference

Metered 0.50 20 Harrill (1986)

Domestic 0.29 30 Geter (2015), Naranjo and others (2013)

Irrigation 0.17 5 Stonestrom and others (2007)

Recharge to the saturated groundwater system is delayed 

as return flow passes through the unsaturated zone between 

the root zone and water table. Annual delay time between 

application of return flow and recharge was estimated at 

each well. Annual delay time was the depth to water table 

divided by pore velocity, which varied by water-use group 

(table 8) because return flow occurred over different areas. For 

example, assuming 130 acres are irrigated with an application 

rate of 7 ft/yr, the return-flow volume applied to the irrigated 

acreage is about 1 ft/yr and the return-flow rate, assuming 

a porosity of 0.2, is 5 ft/yr. Pumped water from domestic 

wells primarily returned through leach fields in septic 

systems, which restricted application areas and increased pore 

velocities, compared to irrigation wells (Naranjo and others, 

2013). Return-flow volume per domestic well is 0.2 acre-ft/ yr 

(0.7 acre-ft/yr × 0.29 fraction). Dividing the return-flow 

volume by a leach-field area of about 0.034 acres (1,500 ft2) 

(Naranjo and others, 2013) and a porosity of 0.2, the returnflow rate is 30 ft/yr. Average pumping for commercial and 

public supply from 1913–2010 was 47 acre-ft/yr (Elliott and 

Moreo, 2018) and, assuming a 5-acre reclamation area, the 

return-flow rate is about 20 ft/yr. Delays between application 

of return flow and recharge generally were less than 10 years 

because depths to water table were less than 70 ft for about 90 

percent of pumped wells (fig. 30). Delays greater than 10 years 

affect about 10 percent of wells where depths to the water 

table range from 200 to 2,060 ft.

Groundwater pumped, consumed, and lost to the 

saturated system is the net pumpage, which is the difference 

between groundwater pumping and return flow (fig. 31). Net 

pumpage in the study area averaged 39,100 acre-ft/yr from 

1960 to 2000, or 83 percent of total groundwater withdrawals. 

Net pumpage averaged 71 percent of total groundwater 

withdrawals during 2010 because irrigation pumping 

decreased as a fraction of all groundwater withdrawals.

Return flow mitigates the effects of pumping on 

capture from discharge areas. In the absence of return 

flow, total groundwater withdrawals would have exceeded 

total predevelopment discharge in the study area during 6 

years between 1960 and 2000 (fig. 31). Instead, return flow 

has resulted in an average net pumpage of 39,100 acre-ft/

yr between 1960 and 2000, which is 73 percent of the 

predevelopment discharge.

Net pumpage (pumping and return flow) causes localized 

effects on water-level declines and capture from discharge 

areas. Pumped intervals in wells and recharge from return flow 

can differ vertically by 50–500 ft and laterally by as much as 

0.6 mi (Moreo and others, 2003). These spatial differences 

can affect local groundwater levels and capture by reducing 

the rate of water-level decline from pumping or the rate of 

capture from discharge areas. These effects are unimportant 

at distances greater than 1–2 mi from areas of pumping and 

return flow (fig. 29).

Areas Affected by Pumping

Areas affected by pumping were delineated with a 

minimum water-level decline of 0.1 ft per decade (fig. 29). 

Delineated areas were compared to the density of pumping 

well locations and volumes pumped (fig. 29). Delineated areas 

also were compared to locations of observation wells with 

observed water-level declines in pumping centers and geologic 

controls, such as low-permeability rocks that function as 

hydraulic barriers (fig. 29). Declining water-level trends in 

wells within the delineated areas are caused by pumping. Net 

pumpage, rather than total groundwater withdrawals, better 

explains water-level declines in wells because net pumpage 

better indicates the actual stresses affecting water levels. 

Therefore, water-level trends from pumping are discussed in 

terms of net pumpage in this section.

Central Amargosa Desert and Pahrump Valley

The central Amargosa Desert and Pahrump Valley are the 

two principal pumping centers in the study area (fig. 32) and 

had maximum measured water-level declines of 50 and 80 

ft, respectively (fig. 33). Water levels declined continuously 

in well AD-5 in the central Amargosa Desert (fig. 32), where 

pumping generally has increased from 1950 to 2010 (fig. 33). 

Water levels in well ESB1 in Pahrump Valley (fig. 32) declined 

80 ft by 1980 and recovered 60 ft by 2010 (fig. 33), to about 

20 ft below predevelopment water levels. The water-level 

trend in Pahrump Valley is a response to net pumping that 

peaked at 40,000 acre-ft/yr in 1968 and decreased to about 

12,000 acre-ft/yr in 2010.
64 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig31

Predevelopment discharge

20

40

60

Groundwater withdrawals, in thousands of acre-feet per year

Projected

EXPLANATION

0

1913 1920 1940 1960

Year

1980 2000 2018

Net pumpage

Return flow

Figure 31. Net groundwater withdrawals and return flow, in the study area, Nevada and California, 1910–2018.

Pumping from the central Amargosa Desert and Pahrump 

Valley affected areas of 300 and 600 mi2, respectively (fig. 32). 

Extents of pumping effects were delineated using decadal rates 

of water-level declines in wells. Decadal rates of water-level 

declines in wells are successively smaller as distance from 

the pumping center increases. Areas within each delineated 

pumping center (fig. 32) had rates of decline of greater than 

0.1 ft per decade, whereas groundwater levels either had rising 

trends (fig. 18) or no trend (neither upward or downward) in 

areas affected minimally or not at all by pumping.

Central Amargosa Desert

Pumping in the central Amargosa Desert has propagated 

north toward Jackass Flats and Bare Mountain and south 

toward Death Valley Junction (fig. 32), as determined from 

water-level declines in wells. Small water-level declines in 

well BGMW-8 (fig. 34B) are not observable 1 mi west in well 

BGMW-6 (fig. 32). Likewise, water-level declines evident in 

well NC-EWDP-Washburn-1X (deep) (fig. 34C) do not extend 

2 mi north to well NC-EWDP-22PA (shallow) (fig. 32), where 

water levels have risen 0.8 ft. Water-level declines in well 

DVJ-02 (fig. 34D) are expected to be limited farther south 

because of the occurrence of low-permeability rocks (fig. 32).

The maximum westward extent of pumping from the 

central Amargosa Desert is uncertain. Pumping has propagated 

into the Funeral Mountains because substantial drawdowns 

of 3 ft per decade were observed in well Travertine Point 1

(fig. 34). Distal pumping effects, if any, from the central 

Amargosa Desert would be masked in Furnace Creek area 

wells by water-level declines from local pumping. Water 

levels have been declining in well WRPMW-5, about 10 mi 

northwest of well Travertine Point 1 (fig. 32), at 1.2 ft per 

decade since 2008. These water levels are affected by local 

pumping for Furnace Creek water supply, where pumped wells 

are less than 1 mi south of well WRPMW-5.

Pahrump Valley

Pumping from Pahrump, Nevada, has propagated to the 

northern and southern extent of Pahrump Valley, into Stewart 

and Chicago Valleys, and north of Shoshone, California 

(fig. 32). Water levels declined at rates of 2.2 and 3.1 ft per 

decade in Last Chance Well and BLM Stewart Valley Well, 

respectively (fig. 35B–C), which are 5 mi northwest of 

pumping wells (fig. 29). Pumping effects did not propagate 

north of these wells because of the occurrence of lowpermeability rocks (Winograd and Thordarson, 1975, p. 

C91–C92; fig. 32). Groundwater levels in wells Jeep Trail

and 021N010E04L01S, 10 mi south and southeast of pumping 

wells (fig. 29), declined at rates of 9 ft per decade between 

1960 and 1980, which coincides with the period of largest 

groundwater withdrawals from Pahrump Valley (fig 35D–E). 

Water levels were recovering in Jeep Trail well after 2004 

from reduced pumping in Pahrump Valley (fig. 35D). Water 

levels in well Hwy 127 MM21-1, about 16 mi west of 

Pahrump Valley pumping wells and 6 mi north of Shoshone 

(fig. 32), declined at a rate of 0.5 ft per decade (fig. 35E). 
Groundwater Development 65

sac19-4233_fig 32

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

AD-5

ESB1

ESB1

NC-EWDPWashburn-1X 

(deep)

DVJ-02

Travertine 

Point 1

BLM Stewart 

Valley

Jeep Trail

Hwy 127 

MM21-1 

021N010E04L01S 

AD-4

ER-6-1-2

main

BGMW-6

BGMW-8

NC-EWDP-22PA

(shallow)

Eagle Mtn 

North

WRPMW-5

GS-1 Well

(AD-12)

JF-3

JF-2

J-13 WW

J-12 WW

Army 1 WW

WW-8 WW-2 (3422 ft)

WW-C (1373-1701 ft)

WW-C (recompleted) 

WW-C-1

CF-2

Bennetts

Spring

Manse

Spring

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

BarrickBullfrog

mine

Buckboard 

Mesa

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

PAHRUMP TO 

DEATH VALLEY

SOUTH

Eagle

Mtn

Emigrant 

Valley

BULLFROG

HILLS

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Observation well or site

Maximum drawdown extent 

from pumping—based on 

a minimum water-level 

decline of 0.1 foot per 

decade in wells and 

known hydraulic barriers

Hydraulic barrier—area of 

low-permeability rock at 

the water table, interpreted 

from the DV3 hydrogeologic framework model

Spring

Extent of megachannel, 

delineated from Winograd 

and Pearson (1976)

Dumont

Dunes

Death

Valley 

Junction

Last Chance Well

Devils

Hole

Figure 32. Observation wells affected by groundwater development and hydraulic barriers, in the study area, Nevada 

and California.
66 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig33

Net pumpage from Pahrump to Death Valley South

Net pumpage from Alkali Flat-Furnace Creek Ranch

0

10

20

30

40

50

60

70

80

90

0

20

40

60

80

100

120

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

B. USGS 360836115531701 162 S21 E54 10AAC 1 ESB1

0

10

20

30

40

50

80

100

120

140

A. USGS 363310116294001 230 S16 E49 18DCCA1 USBLM Well (AD-5)

Year

Depth to water, in feet below land surface

Net pumpage, in thousands of acre-feet per year

EXPLANATION

Measured water levels

Low-permeability rocks west of the Amargosa River limited 

pumping effects from Pahrump Valley from extending west of 

well Hwy 127 MM21-1 (fig. 32).

Discharges from Bennetts and Manse Springs (fig. 32) 

were captured by pumping in Pahrump Valley. All 5,400 

acre-ft/yr (7.5 ft3/s) of discharge from Bennetts Spring 

was captured by 1959 (Harrill, 1986). Bennetts Spring has 

remained dry through 2018. Predevelopment discharge from 

Manse Spring was 4,400 acre-ft/yr (6 ft3/s) and declined 

gradually after development. All discharge from Manse Spring 

was captured by 1977 (Harrill, 1986). Discharge from Manse

Spring resumed by the late 1990s (Buqo, 2004). Pumping 

declines and rising water levels restored Manse Spring, and 

discharge averaged 1,500 acre-ft/yr (2.1 ft3/s) in 2011.

Pahrump Valley, Nevada, 1910–2018. DV3, Death Valley version 3.

Figure 33. Water-level changes in (A) well AD-5 in the central Amargosa Desert and (B) well ESB1 in 

Jackass Flats

Pumping in Jackass Flats, about 15 mi north of the 

central Amargosa Desert (fig. 32), has affected groundwater 

levels but natural water-level rises from recharge mask 

pumping effects (fig. 36). During 1957–2018, total 

withdrawals from wells J-12 WW and J-13 WW were 2,250 

and 4,050 acre-ft, respectively, and these wells supplied about 

90 percent of the 7,000 acre-ft that was pumped from Jackass 

Flats (fig. 36). Water levels in wells JF-2, J-13 WW, and JF-3

rose 1.5 ft in unison from 1997 to 2015 (fig. 36), which is 

consistent with water-level rises from recharge throughout the 

study area (Fenelon and Moreo, 2002; Elliott and Fenelon, 

2010; Fenelon and others, 2012; Jackson and Fenelon, 2018). 

Measured water-level rises were not recoveries from reduced 

pumping because recovery rates would differ between wells. 
Groundwater Development 67

sac19-4233_fig34

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

597

599

601

603

605

607

E. USGS 362230116392901 243 026N003E21L001S Travertine Point 1 (DV-3)

109

111

D. USGS 361818116271802 230 025N005E17J002S DVJ-02

356

358

360

C. USGS 363951116252402 227A S15 E49 11ACD 2 NC-EWDP-Washburn-1X (deep)

338

340

342

B. USGS 364235116441701 230 S14 E46 25BD 1 BGMW-8

0

10

20

A. Alkali Flat-Furnace Creek Ranch

Depth to water, in feet below land surface

Net pumpage,

in thousands of acre-feet per year

Year

EXPLANATION

Measured water levels

Figure 34. Net pumpage in the Alkali Flat-Furnace Creek Ranch groundwater basin (A), and hydrographs 

showing measured water levels in wells BGMW-8 (B), NC-EWDP-Washburn-1X(deep) (C), DVJ-02 (D), and

Travertine Point 1 (E), in the central Amargosa Desert, Nevada and California, 1910–2018.
68 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig35

150

155

160

165

170

D. USGS 360017115460401 162 S22 E55 26DBCA1 JEEP TRAIL

85

90

F. USGS 360337116175101 242 022.5N006E26R001S Hwy 127 MM21-1

160

165

170

175

E. USGS 355655115543101 162 021N010E04L01S

550

555

560

C. USGS 362111116070101 230 S18 E52 27CDC 1 Last Chance Well

25

30

35

40

45

B. USGS 361515116100901 162 S19 E52 31 1 BLM Stewart Valley Well

Depth to water, in feet below land surface

0

10

20

30

40

Net pumpage,

in thousands of acre-feet per year

A. Pahrump to Death Valley South

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Year

EXPLANATION

Measured water levels

Figure 35. Net pumpage in the Pahrump to Death Valley South groundwater basin (A), and hydrographs showing 

measured water levels in wells BLM Stewart Valley Well (B), Last Chance Well (C), Jeep Trail (D), 021N010E04L01S (E), 

and Hwy 127 MM21-1 (F), around Pahrump Valley, Nevada and California, 1910–2018.
Groundwater Development 69

sac19-4233_fig36

708

710

712

714

1950 1960 1970 1980 1990 2000 2010 2020

D. USGS 364528116232201 227A S14 E50 06D 1 JF-3 Well

924

926

928

930

932

C. USGS 364828116234001 227A S13 E50 19C 1 J -13 WW

993

995

997

B. USGS 364945116235001 227A S13 E50 18B 1 UE-25 WT 13 (JF-2)

0

300

600

Groundwater withdrawals,

in acre-feet per year

A. Annual pumpage from Jackass Flats

Depth to water, in feet below land surface

Year

EXPLANATION

Measured water levels

Figure 36. Annual pumping from Jackass Flats (A), and hydrographs showing measured water levels in 

wells JF-2 (B), J-13 WW (C), and JF-3 (D), in Jackass Flats, Nevada, 1950–2018.
70 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Differences in recovery rates would be exaggerated further 

by heterogeneous transmissivities as occurs beneath Jackass 

Flats, where aquifer-test results yield transmissivity estimates 

that ranged from 2,400 to 200,000 ft2/d (U.S. Geological 

Survey, 2018b).

Isolated Areas of Groundwater Development

Isolated areas of groundwater development occur in 

Indian Springs, Frenchman Flat, Buckboard Mesa, CP basin, 

south of Bullfrog Hills, Beatty, Emigrant Valley, and the 

Furnace Creek area (fig. 32). Water-level declines in these 

areas were observed primarily in the pumped wells and at 

distances less than 6 mi from a pumping well. Indian Springs 

is the earliest isolated area, developed in 1942, and pumping 

averaged 600 acre-ft/yr from 1942 to 2010. Groundwater 

development began in Frenchman Flat, Buckboard Mesa, 

and CP basin in 1951, 1963, and 1981, respectively, as water 

supplies for the NNSS. Pumping averaged 470, 120, and 210 

acre-ft/yr from Frenchman Flat, Buckboard Mesa, and CP 

basin, respectively, from the start of development to 2010. 

Pumping rates averaged 1,600 acre-ft/yr south of Bullfrog 

Hills between 1990 and 2000 as the Barrick Bullfrog mine 

(fig. 32) was dewatered. Pumping averaged 2,600 acre-ft/

yr during 1963–2010 from six Beatty Water and Sanitation 

District wells, which supply water for the town of Beatty. 

Pumping averaged 3,900 acre-ft/yr from four water-supply 

wells in Emigrant Valley from 1955–2010. Groundwater in 

the Furnace Creek area was developed during 2009 for public 

supply, where pumping averaged 330 acre-ft/yr from 2009 to 

2014.

Ash Meadows and Devils Hole

Effects of historic pumping from the Ash Meadows 

discharge area were noteworthy because pumping wells 

were within 5 mi of Devils Hole (fig. 37). Groundwater was 

pumped from 1969 to 1982 by Cappaert Enterprises, which 

was Spring Meadows, Inc. prior to 1972 (Dudley and Larson, 

1976). In this report, Spring Meadows, Inc. and Cappaert 

Enterprises pumping is jointly referred to as Cappaert 

Enterprises pumping. A total of 42,100 acre-ft were pumped 

over 14 years (Westenburg, 1993), which is less than 7 percent 

of the 630,000 acre-ft pumped between 1950 and 2010 from 

AFFCR and Ash Meadows groundwater basins (figs. 30

and 32). Water-level declines from pumping by Cappaert 

Enterprises immediately affected water levels in Devils Hole

and recovery from this local pumping has persisted for two 

decades (Williams and others, 1996). Groundwater levels 

declined 2.3 ft in Devils Hole (fig. 4). This would seem like a 

minor change relative to declines of more than 50 ft in other 

pumping centers (fig. 33) except that, prior to pumping in 

1969, less than 2.5 ft of water covered the shelf where Devils 

Hole pupfish feed and reproduce (Dudley and Larson, 1976). 

Water covered only 15 percent of the shelf when water levels 

were lowest in Devils Hole during June of 1972 (Dudley and 

Larson, 1976).

Water levels in Devils Hole were affected by nine nearby 

pumping wells and one injection well (fig. 37). Pumping from 

individual wells uniquely affected Devils Hole depending on 

locations and pumping rates, which were measured frequently 

from 1969 to 1982. Electric-power consumption was measured 

to estimate pumping volumes. Pumped volumes and electricpower consumption were correlated for each well, where 

multipliers ranged from 0.0023 to 0.0041 acre-ft/kilowatt-hour 

(Westenburg, 1993). Pumping rates principally were estimates 

of pumped volumes divided by elapsed times between site 

visits. Electric-power consumption was measured during site 

visits more than 10 times per month from March to July of 

1971, but most measurements between 1969 and 1982 were 

monthly (fig. 38). More than 90 percent of the pumpage was 

from southern wells within 1 mi of Point of Rocks Spring

(fig. 37). Monthly pumping rates from all pumping wells 

ranged from 400 gal/min (0.8 ft3/s) in the winter to 7,500 gal/

min (16.8 ft3/s) in the summer (fig. 38).

Groundwater levels and spring discharges were 

monitored intensively in the Ash Meadows discharge area in 

response to declining water levels in Devils Hole during the 

1970s (Dudley and Larson, 1976). Water levels in Devils Hole

have been measured regularly from an established reference 

point since 1962 but little else was monitored until 1970. 

Water levels in Devils Hole declined about 0.1 ft during 1968 

and at a rate of 0.7 ft/yr during 1969, 1970, and 1971 (fig. 4). 

Monitoring of water levels in wells and discharges from a 

few springs began in 1970; however, intensive monitoring of 

most springs and wells in the Ash Meadows discharge area 

occurred during 1971 and 1972 (Dudley and Larson, 1976). 

Water levels in wells Spring Meadows 7db2 and Point of 

Rocks North (AM-6), near Point of Rocks Spring (fig. 37), had 

maximum declines of 20 and 50 ft, respectively, during the 

summer from 1970 to 1977 (fig. 39). Water levels in pumping 

wells near Point of Rocks Spring also likely had similar trends 

to pumping well Point of Rocks North (AM-6). Persistent 

recovery was observed in most wells between 1978 and 2000.

Stresses Affecting Water Levels in Devils Hole

Pumping by Cappaert Enterprises was the principal 

stress that affected water levels in Devils Hole, but not the 

only stress. Local injection, regional pumping, and natural 

water-level fluctuations measurably changed water levels in 

Devils Hole during the 1970s. Regional pumping and natural 

water-level fluctuations were dominant effects after 1990. All 

stresses must be considered to correctly explain measured 

water-level changes in Devils Hole.
Groundwater Development 71

sac19-4233_fig 37

Last Chance Spring

Big Spring

Fairbanks Spring

Purgatory Spring Well

Jack Rabbit Spring

Five Springs Area

Longstreet 

Spring

Point of Rocks Spring

Soda Spring

Rogers Spring

Crystal Pool

Cold Spring

School

Marsh Spring Spring

North and South

Scruggs Springs

Collins Spring

1 Davis Spring

2 Davis Spring

Devils Hole

Devils Hole Well (AM-5)

Spring Meadows 12

Point of Rocks South (AM-7)

GS-1 Well (AD-12)

Big Spring Well

Jack Rabbit Spring Well

Spring Spring Meadows 12

Meadows

7db2

Spring Meadows 9

School

Spring

Well

GF-2A shallow

GF-2B deep

Rogers Spring ET2 Well

Soda Spring Well

MSH-C

Amargosa Flat Playa Well

Purgatory Spring Well

USFWS Peterson Well

GF-1

Cold Spring Well

Ash Meadows 3 (AM-3)

Peterson Reservoir Well

GF-3

Imvite Road Well

Spring Meadows 6

King Pool Spring

Point of Rocks North (AM-6)

ALKALI FLAT–FURNACE CREEK 

RANCH

ASH MEADOWS

Amargosa 

Desert

Amargosa 

Flat

0 2 MILES

0 2 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Shallow basin fill

Volcanic-sedimentary rocks

Shallow carbonate rocks

Granitic and siliciclastic 

rocks

EXPLANATION

Spring

Observation site

Observation well

Injection well

Ash Meadows pumping 

wells

Northern pumping

Spring Meadows 6

Southern pumping

Hydrogeologic units at water 

table of DV3 hydrogeologic 

model:

116°25' 116°20' 116°15'

36°

30'

36°

25'

36°

20'

Map

area

Study 

area

Figure 37. Hydrogeologic units at the water table, wells, Devils Hole, springs, pumping wells, and injection well [Devils 

Hole Well (AM-5)] in the Ash Meadows discharge area and surrounding areas, Nevada. DV3, Death Valley version 3.
72 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig38 Groundwater withdrawals, in gallons per minute

Groundwater withdrawals, in cubic feet per second

−1

2

0

4

6

8

10

12

14

16

−500

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

1968 1970 1972 1974 1976 1978 1980 1982

Year

Southern pumping

Northern pumping

Spring Meadows 6

Injection well

EXPLANATION

Figure 38. Monthly pumping from northern wells, southern wells, and Spring Meadows 6 well and 

injection into Devils Hole Well (AM-5) by Cappaert Enterprises in the Ash Meadows discharge area, 

Nevada, 1968–82.

Water was injected into Devils Hole Well (AM-5) to 

mitigate declines in Devils Hole from pumping by Cappaert 

Enterprises during the peak irrigation season (fig. 38). Devils 

Hole Well (AM-5) is 900 ft east of Devils Hole (fig. 37). 

Injection began in June 1973 and continued seasonally through 

1977 (fig. 38). The source of injected water was spring 

discharge diverted from King Pool Spring that would not 

have readily returned to the groundwater system otherwise. 

A single injection rate of 400 gal/min was reported during 

summer 1973 (Larson, 1974a), which caused water levels to 

rise 20 ft in Devils Hole Well (AM-5) (fig. 39). Water levels 

rose between 30 and 40 ft during injection periods from 1974 

to 1977 (fig. 39). The increase in water-level rises from 20 ft 

to between 30 and 40 ft were attributed to “... partial plugging 

of the perforations in the well by algae, air entrainment, or 

physical change in the well” (Larson, 1975).

Water levels in Devils Hole fluctuate naturally in response 

to Earth tides, barometric-pressure changes, earthquakes, and 

episodic recharge. Water levels fluctuate less than 0.4 ft in 

response to short-term tidal and barometric stresses, where 

Earth tides are the dominant stress (Dudley and Larson, 1976, 

p. 11). The range of short-term Earth tidal fluctuations can be 

observed with less than a month of continuous water-level 

measurements. Seismic waves from nuclear detonations and 

earthquakes have perturbed water levels in Devils Hole, but 

effects typically dissipate in less than a few hours (Dudley 

and Larson, 1976). Coseismic water-level responses to crustal 

deformation can persist for years, but ultimately dissipate 

(Cutillo and Ge, 2006). Landers/Little Skull Mountain and 

Hector Mine earthquakes initially displaced water levels 

in Devils Hole by 0.4 and 0.1 ft, respectively (Cutillo and 

Ge, 2006). Episodic recharge caused long-term water-level 

fluctuations in Devils Hole. Cycles of long-term fluctuations 

exceed 120 years, where multiple-decade periods of declining 

or rising water levels are the result of dry or wet periods 

(fig. 17).
Groundwater Development 73

sac19-4233_fig39

B. USGS 362529116171100 230 S17 E50 36DDC 1 Devils Hole Well (AM-5)

A. Monthly pumping and injection from Ash Meadows discharge area

C. USGS 362432116165701 230 S18 E51 07BBBB1 Point of Rocks North (AM-6)

D. Spring Meadows 7db2

10

20

30

40

50

60

10

20

30

40

50

60

70

80

-10

0

10

20

30

Depth below land surface, in feet

−2

0

2

4

6

8

Groundwater withdrawals,

in thousands of gallons per minute

1965 1970 1975 1980 1985 1990 1995 2000

Year

Pumping

Injection

Measured water levels

EXPLANATION

Figure 39. Monthly pumping and injection from the Ash Meadows discharge area (A), and 

hydrographs showing measured water levels in wells Devils Hole Well (AM-5 ) (B), Point of Rocks 

North (AM-6) (C), and Spring Meadows 7db2 (D), during groundwater development by Cappaert 

Enterprises, Nevada, 1965–2000.
74 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Devils Hole Water-Level Model

Water levels in Devils Hole were simulated with a 

water-level model in this study (Jackson and Halford, 2020) 

so that natural water-level fluctuations could be estimated 

and differentiated from pumping effects (fig. 40). Waterlevel changes in Devils Hole from natural fluctuations must 

be explained in addition to changes from pumping. This is 

because the U.S Supreme Court (Cappaert v. United States) 

mandated a minimum pool elevation of 2.7 ft below the 

reference point, whether or not water-level changes are 

due solely to pumping (Williams and others, 1996). Timevarying natural fluctuations were estimated with the waterlevel model and subtracted from water-level measurements 

in Devils Hole to obtain a Devils Hole hydrograph affected 

by pumping only for calibration of numerical groundwater 

models. Groundwater models were used to differentiate effects 

from different pumping centers on water levels in Devils 

Hole. Long-term natural fluctuations were removed because 

groundwater models in this study do not simulate time-varying 

recharge or earthquakes.

Natural fluctuations simulated include Earth tides, 

earthquakes, episodic recharge, and steady discharge. Landers/

Little Skull Mountain and Hector Mine earthquakes were 

simulated because displacement and dissipation affected water 

levels for multiple years (Cutillo and Ge, 2006). Recharge 

was simulated using winter precipitation (October–March) in 

excess of 6 in. from the south–central Nevada precipitation 

index (fig. 17) and natural discharge from springs and 

phreatophytes was assumed steady. In this report, longterm natural fluctuations refer to water-level fluctuations in 

response to time-varying recharge and steady discharge.

The assumption of steady natural discharge is violated 

near Devils Hole, but does not affect water-level model results. 

Spring discharge was not steady during pumping by Cappaert 

Enterprises (Dudley and Larson, 1976). Spring capture and 

pumping by Cappaert Enterprises were correlated highly 

for monthly pumping estimates. Net effects of pumping by 

Cappaert Enterprises and spring capture were estimated in the 

analytical model of water levels in Devils Hole.

Effects from injection into Devils Hole Well (AM-5), 

local pumping, and regional pumping were approximated 

with Theis transforms (Halford and others, 2012). Combined 

pumping effects were estimated and cannot be attributed to 

individual pumping wells or pumping centers because of 

correlation between Theis transforms.

Pumping from the AFFCR groundwater basin and NNSS 

wells in carbonate rocks (figs. 29 and 39) was a regional stress 

that affected water levels in Devils Hole. Effects of pumping 

more than 600,000 acre-ft from the AFFCR groundwater 

basin are attenuated in the Ash Meadows groundwater basin 

because a relatively small corridor near well AD-4 (fig. 32) 

connects the two basins (Claassen, 1985 p. F19; Fenelon 

and others, 2016, p. 6). Pumping from NNSS wells Army 1 

WW, ER-6-1-2 main, WW-2 (3422 ft), WW-C (1373-1701 ft), 

WW-C (recompleted), and WW-C-1 (fig. 32) totaled 18,000 

acre-ft and likely affected water levels in Devils Hole. This 

is because these NNSS wells pump water from carbonate 

rocks near a confined transmissive feature, the megachannel 

(fig. 32; Winograd and Pearson, 1976). Pumping from Indian 

Springs also likely affected water levels in Devils Hole, but 

effects of pumping from NNSS and Indian Springs cannot be 

differentiated with an analytical water-level model (Bedinger 

and Harrill, 2006).

Episodic recharge had to exceed steady discharge to 

explain annually averaged water levels rising 0.43 ft in Devils 

Hole from 2005–2015 (fig. 40). Water levels in Devils Hole

declined between 1990 and 2005 as regional pumping from 

AFFCR and Ash Meadows groundwater basins increased 

(fig. 30). Nevada Division of Water Resources inventories of 

pumpage from the Amargosa Desert hydrographic area show 

less than 2 percent change during 2006–10 and 2011–15. 

Because regional pumping changed little from 2005–2015, 

water levels in Devils Hole would have stabilized or declined 

after 2005 in the absence of episodic recharge events. 

Recharge exceeding steady discharge after 2005 is consistent 

with ubiquitous rising water levels throughout the study area 

(Fenelon and Moreo, 2002; Elliott and Fenelon, 2010; Fenelon 

and others, 2012; Jackson and Fenelon, 2018).

Estimated long-term natural fluctuations suggest that 

water levels in Devils Hole would have risen about 1 ft from 

1973–2018 in the absence of pumping and injection (fig. 40). 

Water-level rise estimates are interpretative because pumpingrecovery effects and recharge are correlated. Rises from 

recharge of as much as 2.7 ft from 1973–2018 were estimated 

with alternative water-level models of Devils Hole. Estimated 

rises greater than 1 ft were rejected because comparable 

water-level rises in distant wells bounded estimates in Devils 

Hole. Proximity to discharge locations subdues water-level 

fluctuations and Devils Hole is within 1–5 mi of all major 

springs in the Ash Meadows groundwater basin (fig. 37). 

Estimated rises between 1973 and 2018 in wells U-19bk and 

USFWS DR-1 were 2 and 5 ft, respectively (fig. 18). These 

wells are 20 and 50 mi from their respective discharge areas 

(fig. 16) and are not affected by pumping. Natural water-level 

fluctuations from recharge in Devils Hole should be less 

than in wells far removed from discharge areas such as wells 

U-19bk and USFWS DR-1.
Groundwater Development 75

sac19-4233_fig40

Year

Landers/Little

Skull Mountain

Hector Mine

U.S. Supreme Court mandated minimum water level

−4

−3

−2

−1

0

Depth below reference, in feet

−3

−2

−1

0

Water-level change, in feet

A

B

1900 1920 1940 1960 1980 2000 2020

Natural water-level fluctuations

Water-level model of all stresses

Long-term trend of recharge and steady discharge

Earthquakes

Pumping effects without natural fluctuations

Measured water levels

EXPLANATION

Figure 40. Estimated natural water-level fluctuations (includes short-term and long-term natural stresses), 

long-term natural trend of recharge and steady discharge, measured water levels, water-level model that 

includes all natural and pumping stresses, and pumping effects without natural fluctuations in Devils Hole, 

Nevada, 1900–2018.
76 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Integrated Estimation of Recharge and 

Hydraulic-Property Distributions with 

Numerical Models

Recharge and hydraulic-property distributions were 

estimated by simultaneously calibrating four, threedimensional, numerical groundwater models of the study area. 

When the four models are coupled, the integrated model is 

referred to as the DV3 model. Multiple models with identical 

spatial extents were constructed to simulate and differentiate 

the effects of predevelopment flow; changes from groundwater 

development (two models); and changes from a large-scale, 

multiple-well aquifer test (MWAT; table 2). Interpretation 

of measured stress-response pairs with separate models 

introduced fewer errors than simulation of all responses 

with a single generalized model. This was because boundary 

conditions could be better constrained to known stresses and 

corresponding simulated responses could be compared to 

appropriate observations. For example, discharge from Big 

Spring averaged 2.4 ft3/s prior to development, with a pool 

altitude of 2,240 ft. Multiple models allowed simulation 

of Big Spring as a specified discharge of 2.4 ft3/s prior to 

development and as a head-dependent boundary during 

groundwater development. This prevented misfits between 

simulated and measured pool altitudes from affecting 

simulated capture during groundwater development.

Groundwater-flow equations were solved using the USGS 

finite-difference model, MODFLOW (Harbaugh, 2005). The 

four coupled (stress-response) groundwater models were 

calibrated simultaneously using the Parameter ESTimation 

code (PEST; Doherty, 2010a). Archives of the integrated DV3 

model containing executables, PEST calibration files, stressresponse models, and utilities for drawing maps are available 

in Jackson and Halford (2020).

Common Construction of Models

All groundwater models that were developed for the DV3 

project shared a common domain, gridding, hydrogeologic 

framework, and hydraulic properties. Model domains extended 

laterally to the edges of the study area (fig. 41). Each model 

was divided areally into 268 rows of 221 columns of variably 

spaced, rectangular cells that ranged from 820 ft (250 m) 

to 4,920 ft (1,500 m) on a side. Furnace Creek area, Devils 

Hole area, Rainier Mesa, and Yucca Flat were areas of finer 

discretization (fig. 41). The model grid is oriented north-south 

in Universal Transverse Mercator (UTM), zone 11, North 

American Datum of 1983 (NAD 83) projection, and the X 

and Y coordinates of the northwest corner are 494,000 and 

4,175,500 m, respectively.

All groundwater model grids were divided into six layers 

and coincided with the grid of the hydrogeologic framework, 

which extended vertically from the water table to 3,300 ft 

(1,000 m) below the National Geodetic Vertical Datum of 

1929 (NGVD29) (fig. 26). Layer 1 of the groundwater models 

was 1-ft thick to better simulate groundwater/surface-water 

interaction and drainage at the water table. Groundwater 

model layers 2–6 coincided with hydrogeologic framework 

layers 1–5. Hydrogeologic units in groundwater model layers 

1 and 2 were identical. Tops of layers 3–6 nominally occurred 

at depths of 164, 330, 800, and 1,600 ft (50, 100, 250, and 

500 m) below the water table or followed contacts between 

hydrogeologic units where well control was sufficient (fig. 26). 

The bottom of layer 6 extended to 3,300 ft (1,000 m) below 

NGVD29.

Saturated thicknesses of all model layers were specified 

and did not change in response to simulated pumping. 

Therefore, the simulated water table does not deform or move 

through layers. This approach was adopted because models 

with specified thicknesses converge and execute quickly 

compared to models that simulate transmissivity as a function 

of head (Sheets and others, 2015). The central Amargosa 

Desert and Pahrump Valley were the only areas where this 

approach could be questioned, with maximum declines of 

50 and 100 ft, respectively (fig. 33). Maximum change in 

saturated thickness was less than 30 percent of model cell 

thicknesses, which affects simulated drawdowns less than 20 

percent (Sheets and others, 2015).

Distributing Hydraulic Properties And Recharge

Heterogeneous hydraulic-property (and recharge) 

distributions were estimated with PEST using pilot points. 

Hydraulic-property values of hydraulic conductivity, specific 

yield, and specific storage were estimated at pilot points 

(RamaRao and others, 1995), where the locations of pilot 

points were user-specified. In this study, more pilot points 

occurred in areas where more data are available to constrain 

hydraulic-property estimates. Estimated hydraulic-property 

values at user-specified locations were translated into 

continuous hydraulic-property fields by interpolation with 

kriging using variograms (Doherty, 2010b).

Isotropic, exponential variograms defined spatial 

variability of log-hydraulic properties, where spatial 

correlation was specified with user-defined ranges (distances). 

Spatial correlation is assumed non-existent where distances 

between the interpolated location (cell center) and known 

value (pilot point) exceed the range. A hydraulic-property 

value at a cell functionally was an inverse-distance weighted 

average of the eight nearest pilot-point values if all distances 

between cell center and pilot points were less than the range. 

A hydraulic-property value at a cell is a simple average if 

distances between a cell center and the eight nearest pilot 

points all exceed the range.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 77

sac19-4233_fig 41

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Devils Hole 

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

DV3 model grid cell— 

ranging in length from 820 

to 4,921 feet (250 to 1,500 

meters) Dumont

Dunes

Figure 41. Boundary of Death Valley version 3 (DV3) model and areas of finer discretization, in the study area, Nevada 

and California.
78 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Interpolated hydraulic properties varied laterally but were 

uniform with depth in multiple-layer hydrogeologic units. For 

example, consider the distribution of hydraulic-conductivity 

values within a hypothetical framework consisting of basin fill, 

volcanic rocks, and carbonate rocks (fig. 42). The thickness 

of carbonate rocks varies with depth but is collapsed into a 

two-dimensional array of the laterally mapped extent (fig. 42). 

In this study, each hydrogeologic unit is a unique zone in 

MODFLOW and the pilot points were grouped by zone. This 

means that only pilot points within the hydrogeologic unit 

(zone) were used in the interpolation of hydraulic-property 

values at model cells within the hydrogeologic unit. The 

hypothetical carbonate rocks (fig. 42) have three pilot points 

that only are used in the lateral interpolation of hydraulic 

conductivities within the carbonate rocks. The estimated 

hydraulic-conductivity values at each lateral (X,Y) location 

in the carbonate rocks are assigned to all model layers where 

the carbonate rocks occur. Therefore, hydraulic properties are 

estimated at pilot points, interpolated laterally within each 

hydrogeologic unit, and then assigned the same value for all 

layers where the hydrogeologic unit occurs. Map extents of 

hydrogeologic units and pilot points for each hydrogeologic 

unit are provided as spatial coverages in Jackson and Halford 

(2020).

Hydraulic properties are assumed to be laterally and 

vertically isotropic because of practical limitations. Outcrops 

clearly indicate that bedding occurs at every conceivable 

dip and orientation (Sweetkind and others, 2010). Flow logs 

(Garcia and others, 2010) and packer tests (Frus and Halford, 

2018) show extreme anisotropy or heterogeneity across 

intervals of less than 200 ft. None of these details are indicated 

in the hydrogeologic units, which are featureless groups 

of rocks. Heterogeneity is simulated entirely by contrasts 

in hydraulic properties within and between hydrogeologic 

units. Lateral contrasts were simulated by adding pilot points 

to hydrogeologic units, where greater pilot-point density 

allows for increased heterogeneity. Vertical contrasts were 

simulated exclusively by differences in hydraulic properties 

between hydrogeologic units as occurred beneath Rainier 

Mesa (fig. 26). Basin fill in Amargosa Desert and Pahrump 

Valley was differentiated with depth by subdividing basin fill 

into three units (table 7) to simulate water table (unconfined) 

and confined conditions. Heterogeneity and anisotropy are 

correlated, where large degrees of anisotropy can be simulated 

with large contrasts in hydraulic properties.

Hydraulic Conductivity

Hydraulic conductivities and layer thicknesses define 

simulated transmissivities and were assigned with the 

Layer-Property Flow package in MODFLOW (Harbaugh, 

2005). Heterogeneous hydraulic-conductivity distributions 

were estimated for each hydrogeologic unit. Hydraulic 

conductivities are estimable at pilot points in areas where data 

exist because the parameters are sensitive to and informed by 

the data. However, in areas where no data exist, hydraulicconductivity estimates were constrained by conceptual 

transmissivity distributions. A conceptual transmissivity 

distribution was estimated for each hydrogeologic unit 

from aquifer-test results. Hydraulic conductivities for a 

hydrogeologic unit initially were conceptual transmissivities 

divided by model thicknesses of a hydrogeologic unit. 

For example, broad areas of uniform transmissivity were 

postulated for shallow carbonate rocks to provide initial 

hydraulic conductivities for this hydrogeologic unit (fig. 43).

Hydraulic conductivities were distributed with pilot 

points so that observed spatial variability could be simulated 

in hydrogeologic units (fig. 21). Isotropic, exponential 

variograms were used to define spatial variability of loghydraulic conductivities with ranges of 1.5–9 mi. Ranges of 

variograms were less than 3 mi in areas of high pilot-point 

densities (fig. 44) so that interpolated hydraulic conductivities 

could vary more. Distributed hydraulic conductivities in 

hydrogeologic units were mapped to the hydrogeologic 

framework and parsed to a two-dimensional array for each 

model layer (fig. 42). All groundwater models used the same 

arrays of hydraulic conductivity.

Hydraulic conductivities were specified with 2,476 pilot 

points and pilot-point density increased in areas where waterlevel measurements, spring discharges, and transmissivity 

estimates were more prevalent (fig. 44). Pahute Mesa, Rainier 

Mesa, Yucca Flat, central Amargosa Desert, Ash Meadows 

discharge area, Furnace Creek area, and northern Pahrump 

Valley were areas with high data densities (figs. 19 and 29).

Pilot-point occurrence differed between model layers. 

Pilot-point occurrence at the water table adequately shows 

variations in pilot-point density, even though only 45 percent 

of pilot points occur at the water table (fig. 44). Additional 

pilot points in deeper hydrogeologic units are not shown in 

figure 44. For example, shallow carbonate rocks are overlain 

by basin fill, volcanic rocks, and volcanic-sedimentary rocks 

in Yucca Flat and the Ash Meadows discharge area (figs. 43

and 44). Compared to other hydrogeologic units, more 

hydraulic data exist for these shallow carbonate rocks, which 

supports adding more pilot points because more data are 

available to inform hydraulic-conductivity estimates during 

model calibration. Hydraulic data include measured water 

levels in more than 100 wells, discharges and pool altitudes 

from 19 springs, water-level changes and spring captures from 

pumping by Cappaert Enterprises, and drawdowns from the 

well ER-6-1-2 main MWAT.

Hydraulic conductivities were specified at pilot points 

where knowledge of the mapped lithology constrained 

hydraulic-conductivity estimates despite an absence of 

hydraulic data. For example, the floor of Death Valley is 

classified as basin fill in the hydrogeologic framework 

(fig. 44). The upper 1,000 ft of sediments consist of alternating 

layers of salt and clay in boreholes north and south of 

the Furnace Creek area (Hunt and others, 1966, p. B42). 

Hydraulic conductivities of salt and clay are variable, but 

generally do not exceed 0.0001 ft/d (Jackson and others, 

2018). Representative hydraulic conductivities were assigned, 

not estimated, during model calibration.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 79

sac19-4233_fig 42

Basin fill

Volcanic rocks

Carbonate rocks

EXPLANATION

Hydraulic conductivity, in feet per day

0.01 0.1 1 10 40

EXPLANATION

Laterally interpolated hydraulic 

conductivities in mapped extent 

of carbonate rocks

Pilot point and hydraulic 

conductivity, in feet per day

Vertically uniform 

hydraulic conductivity 

in a hydrogeologic unit

Hydraulic conductivity distribution written 

as two-dimensional arrays consistent with 

MODFLOW layers

Hydrogeologic framework

Map extent of 

carbonate rocks

Hydraulic conductivity 

distribution

20

44

0.15

Figure 42. Process for distributing hydraulic conductivities from pilot points to U.S. Geological Survey 

finite-difference model (MODFLOW) layers through hydrogeologic units in a hydrogeologic framework.
80 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 43

Devils Hole 

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Conceptual transmissivity 

distribution in shallow 

carbonate rocks, in feet 

squared per day

Less than 10

10 to 100

100 to 1,000

1,000 to 10,000

10,000 to 100,000

100,000 to 1,000,000

1,000,000 to 29,000,000

Pilot point

Dumont Observation site

Dunes

Figure 43. Conceptual transmissivity distribution in shallow carbonate rocks and hydraulic-conductivity pilot points for 

the shallow carbonate rocks, in the study area, Nevada and California.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 81

sac19-4233_fig 44

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Emigrant 

Valley

Devils Hole 

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Observation site

Ash Meadows National 

Wildlife Refuge

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Pilot point

Shallow basin fill

Volcanic rocks

Volcanic-sedimentary rocks

Carbonate rocks

Low-permeability carbonate 

rocks

Granitic and siliciclastic 

rocks

Hydrogeologic units at water 

table of Death Valley 

version 3 model

Dumont

Dunes

Figure 44. Extents of all hydrogeologic units and hydraulic-conductivity pilot points at the water table, in the study area, 

Nevada and California.
82 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Specific Yield And Specific Storage

Storativity distributions were estimated for hydrogeologic 

units by categorizing these units in the DV3 hydrogeologic 

framework as either basin fill or consolidated rocks. The 

basin fill categorization includes basin fill and volcanicsedimentary rocks, whereas consolidated rocks consist of 

carbonate, volcanic, and low-permeability rocks (table 7). 

A simplified framework of basin fill and consolidated rocks 

was used because storativities are less variable than hydraulic 

conductivities. Storativity is specific yield plus specific storage 

times thickness. Specific yields typically range from 0.05 to 

0.25 in basin fill and from 0.01 to 0.05 in consolidated rocks. 

Specific-storage values typically range from 1 × 10-6 to 5 × 

10−6 1/ft, regardless of hydrogeologic unit. Specific-yield 

and specific-storage values only were estimated (with PEST) 

in areas where saturated rocks were affected by pumping 

(fig. 29). In areas where aquifers were unaffected by pumping, 

specific yields of 0.1 and 0.02 were assigned to basin fill and 

consolidated rocks, respectively, and a specific-storage value 

of 2 × 10-6 1/ft was assigned.

Storativities were estimated (or assigned) using either 

specific yield or specific storage in MODFLOW layers. 

Storativities in layer 1 were interchangeable with specific 

yields because layer 1 is 1-ft thick and specific storage is at 

least three orders of magnitude smaller than specific yield. 

Specific storages were used in layers 2–6 and reported as 

storage coefficients, which is specific storage times thickness. 

Specific storages estimated (in pumping areas) and assigned 

(in nonpumping areas) were uniform with depth and 

independent of hydrogeologic units because specific storages 

range from 1 × 10-6 to 5 × 10-6 1/ft for all hydrogeologic 

units. For example, the estimated specific storage at an (X,Y) 

location is assigned to model layers 2–6 and the storage 

coefficient is computed by multiplying the specific storage 

by the total thickness of layers 2–6. Therefore, the specificstorage distribution has lateral (X,Y) heterogeneity where 

estimated, but is uniform with depth at each spatial (X,Y) 

location.

Specific-storage values estimated with PEST ranged from 

2 × 10-9 to 1 × 10-5 1/ft, which are beyond expected values of 

1 × 10-6 and 5 × 10-6 1/ft. Extreme underestimation of specific 

storages likely compensated for overestimating contributing 

thicknesses of consolidated rocks. For example, if a 10-ft-thick 

unit with a specific storage of 2 × 10-6 1/ft was simulated 

incorrectly with a 1,000-ft-thick layer, then the correct storage 

coefficient would be simulated if a specific storage of 2 × 10-8

1/ft is estimated. Correction of hydrogeologic unit thicknesses 

was beyond the scope of this study.

Specific yields and specific storages were estimated with 

420 pilot points so that spatial variability could be simulated 

in hydrogeologic units. Interpolated specific yields varied 

laterally within basin fill and consolidated rocks in model 

layer 1. Interpolated specific storages varied laterally in model 

layers 2–6 but were uniform with depth. Isotropic, exponential 

variograms defined spatial variability of log-specific yields 

and log-specific storages with a range of 12 mi. Distributed 

specific yields and specific storages were mapped to the 

hydrogeologic framework and parsed to two-dimensional 

arrays for each MODFLOW model layer as was done with 

hydraulic conductivities (fig. 42). All transient (pumping) 

groundwater models used the same array of specific yield and 

arrays of specific storages.

Recharge

Recharge was distributed throughout the steady-state 

model simulating predevelopment flow with a total of 521 

pilot points (fig. 45). Recharge rates were estimated at pilot 

points with PEST, then interpolated from pilot points to 

model cells with kriging, similar to the interpolation method 

used for distributing hydraulic properties (Doherty, 2010b). 

Spatial variability of recharge was defined with an isotropic, 

exponential variogram, where nugget and range were 0 and 

30,000 ft, respectively.

Recharge zones (fig. 16) were used for estimating 

heterogeneous recharge-rate distributions (fig. 45), similar 

to the hydrogeologic unit zones used for estimating 

heterogeneous hydraulic-property distributions. Recharge 

zones were delineated for runoff areas downgradient of 

low-permeability rocks, channels of the Amargosa River 

and Fortymile Wash, and other geographic areas (fig. 16). 

Recharge zones informed the objective function at sufficiently 

large scales that relative water availability was well defined 

between zones. For example, annual recharge volumes from 

the Spring Mountains greatly exceed annual recharge volumes 

from the Funeral Mountains. Annual recharge volumes to 

these zones are well defined relative to cell-by-cell estimates 

in the conceptual recharge distribution (fig. 16).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 83

sac19-4233_fig 45

Devils Hole 

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

AD-4

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

EXPLANATION

Recharge pilot point

Groundwater basin 

boundary modified from 

Fenelon and others (2016)

Nevada National Security 

Site boundary and 

internal operations areas

Observation well or site

0.0001 to 0.002 (5%)

0.002 to 0.02 (18%)

Recharge rate, in feet per 

day—recharge rates 

estimated from calibrated 

Death Valley version 3 

model. Percentage of total 

recharge shown in 

parentheses

Negligible recharge (0%)

0.02 to 0.2 (42%)

0.2 to 2 (35%)

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

20 KILOMETERS

116°30' 115°30'

37°

30'

36°

30'

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

Shoshone 

Mountain

Dumont

Dunes

Figure 45. Estimated recharge distribution and recharge pilot points, from the Death Valley version 3 steady-state model 

(DV3-SS), in the study area, Nevada and California.
84 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Stress-Response Models 

Predevelopment conditions; the well ER-6-1-2 main

MWAT; groundwater development in Ash Meadows, 

AFFCR, and PMOV groundwater basins; and groundwater 

development in the PDVS groundwater basin were simulated 

with four separate, but coupled, stress-response models 

(table 2). The DV3-SS (steady-state) model simulated 

predevelopment conditions and informed estimates of 

recharge rates and hydraulic conductivities. The DV3-ER612 

model simulated drawdowns from pumping during the well 

ER-6-1-2 main MWAT, and informed estimates of hydraulic 

properties between northern Yucca Flat and the Ash Meadows 

discharge area. The DV3-AM-AFFCR model simulated 

changes from groundwater development from 1950–2018 in 

the Ash Meadows, AFFCR, and PMOV groundwater basins. 

The DV3-PDVS model simulated changes from groundwater 

development from 1913–2018 in the PDVS groundwater 

basin. Transient DV3-ER612, DV3-AM-AFFCR, and DV3-

PDVS models informed estimates of hydraulic conductivity, 

specific yield, and specific storage in areas where pumping 

measurably changed groundwater levels or spring discharges.

Common Boundary Conditions

The outer edges of the study area (fig. 41) and the bottom 

of layer 6 at 3,300 ft (1,000 m) below NGVD29 are no-flow 

boundaries in all groundwater models. Internal boundaries 

between groundwater basins were not simulated explicitly 

as no-flow boundaries. Instead, hydrogeologic units formed 

hydraulic barriers or conduits to groundwater flow based on 

estimated hydraulic properties. Hydraulic-property estimates 

were informed by water-level altitudes, lateral and vertical 

water-level differences, recharge, predevelopment discharges, 

water-level changes from pumping, captures of spring 

discharges, captures of discharge from ET areas, transmissivity 

estimates from aquifer-test results and specific capacity, and 

hydraulic inferences from lithologic data, such as siliciclastic 

and granitic rocks functioning as hydraulic barriers.

The top surface of each groundwater model was the 

water table. The DV3-SS model simulated recharge to the 

top surface of layer 1 across the entire model domain. The 

transient DV3-ER612, DV3-AM-AFFCR, and DV3-PDVS 

models are superposition models, where the top of layer 1 is 

the predevelopment water table (Halford and Plume, 2011). 

Transient superposition models have initial heads of 0 ft, 

which are conceptualized as no change or drawdown from 

predevelopment conditions. Simulated water-level changes are 

relative to predevelopment heads.

Predevelopment—DV3-SS Model

Steady-state flow during predevelopment conditions 

was simulated so that recharge and transmissivities (through 

hydraulic conductivities) could be estimated. Annual 

recharge volumes were defined primarily by predevelopment 

discharges. Elevated water levels in areas of limited recharge 

identified low-permeability rocks. Transmissivities of areas 

between Devils Hole and Army 1 WW (fig. 32) were defined 

primarily by discharges from springs in the Ash Meadows 

discharge area. Volume and water chemistry of discharges 

from the Furnace Creek area defined transmissivities 

upgradient in the central Amargosa Desert (Winograd and 

Thordarson, 1975, p. C112). Transmissivities of areas between 

the Nopah Range and Amargosa River were defined by 

discharges from the Lower Amargosa area. Transmissivities 

between Oasis Valley and Pahute Mesa were defined by 

discharges from Oasis Valley and aquifer-test results. 

Transmissivities in Yucca Mountain, Jackass Flats, Yucca 

Flat, Frenchman Flat, Indian Springs, Emigrant Valley, the 

central Amargosa Desert, and Pahrump Valley were informed 

by aquifer-test results and specific capacities (fig. 19); 

however, the transient groundwater models further refined 

transmissivities in these areas.

Lateral Flow Across Study Area Boundary

The study area primarily is isolated from surrounding 

groundwater basins by low-permeability rocks and 

groundwater divides (Fenelon and others, 2016), as 

discussed in the section, “Description of Study Area.” The 

outer boundaries of the study area are simulated as no-flow 

boundaries. Groundwater flow across the northern and eastern 

boundaries between Gold Flat and Pahranagat Valley has 

been suggested previously (Winograd and Thordarson, 1975; 

Heilweil and Brooks, 2011; Fenelon and others, 2016), but 

flow across these boundaries is expected to be limited.

Potential groundwater flow across the lateral studyarea boundary was not precluded by no-flow boundaries 

because potential lateral flow was accommodated in simulated 

recharge estimates. For model cells along the periphery of 

the model domain, adding recharge to tops of model cells or 

specifying flow at any depth would similarly affect simulated 

water levels. Differentiating recharge and lateral flow along 

the study-area boundary was not possible because little data 

exist. Less than a dozen wells are available within 10 mi of the 

northern and eastern boundaries of the study area. Estimated 

recharge along the periphery of the study area should be 

interpreted as undifferentiated recharge and lateral flow.

Water Table and Perched Groundwater Assumptions

The top surface of all groundwater models is the water 

table, which encompasses the uppermost occurrence of 

saturation and includes perched and semi-perched intervals. 

Inclusion of perched groundwater in the DV3-SS model 

allows for the simulation of groundwater-flow paths from 

nuclear test locations in Rainier Mesa and Shoshone 

Mountain, which were detonated within the perched system. 

Perched and semi-perched groundwater also was included 

in Bare Mountain, Eleana Ridge, north of Climax Mine, 

Skull Mountain, Sheep Range, Greenwater Range, and Black 

Mountains (fig. 25).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 85

Errors introduced by simulating the unsaturated zone 

beneath perched intervals with a saturated groundwater 

model are assumed to be negligible at the regional scale. 

Infiltration is vertical through the unsaturated zone from 

overlying perched intervals into the underlying saturated 

flow system. When the unsaturated zone beneath a perched 

zone is simulated as saturated, minor amounts of vertical 

flow are simulated erroneously as lateral flow. For example, 

in Rainier Mesa, open intervals in wells ER-12-3 piezometer

and ER-12-3 main are at average depths of 1,700 and 4,000 

ft below land surface, respectively, with about 1,000 ft 

of unsaturated zone between the two open intervals. The 

vertical gradient averages 0.8 ft/ft, whereas lateral gradients 

range from 0.08 ft/ft in volcanic tuffs at the perched water 

table to 0.008 ft/ft in the saturated carbonate rocks at the 

regional water table (U.S. Department of Energy, 2018). 

By simulating the 1,000-ft unsaturated zone as part of the 

saturated flow system, less than 100 ft of lateral movement 

would be simulated in the unsaturated zone assuming a 

vertical gradient of 0.8 ft/ft and a maximum lateral gradient 

of 0.08 ft/ft. Erroneously simulating less than 100 ft of 

lateral movement in the unsaturated zone is not materially 

different than the conceptually correct 0 ft. Perched intervals 

and underlying saturated rocks coalesce into a single, thick 

saturated zone within 1 mi of outcrops beneath Rainier Mesa 

(U.S. Department of Energy, 2018), which suggests perched 

intervals are areally limited in the study area.

Boundary Conditions

More than 96 percent of the predevelopment discharge 

was specified in the DV3-SS model (fig. 46) using the 

well package in MODFLOW (Harbaugh, 2005). Specified 

discharges from springs totaled 30,300 acre-ft/yr as measured 

(table 9), where 18 of 27 springs were in the Ash Meadows 

discharge area (fig. 46). Diversions from Furnace Creek 

Wash also were included in the spring category (table 9). 

The remaining 23,400 acre-ft/yr of specified discharge was 

evapotranspired discharge in the Ash Meadows discharge area, 

Oasis Valley, Furnace Creek area, Franklin Well area, Stewart 

Valley, Pahrump Valley, Lower Amargosa area, and Saratoga 

Spring area, which were simulated as specified discharges 

from layer 1 (fig. 46). Evapotranspired discharge in each 

model cell was computed by mapping all ET unit areas in each 

cell and multiplying the ET areas by their respective discharge 

rates. Unlike the Ash Meadows discharge area, spring 

discharges and ETGW from downgradient phreatophytes were 

not differentiated in Oasis Valley and the Lower Amargosa 

area because springs and their downgradient ET units typically 

occurred within a cell. Therefore, total discharge from each 

model cell in Oasis Valley and the Lower Amargosa area is 

the sum of all discharge from springs and ET areas within 

each cell. Discharge from ET areas was specified from the 

southern two-thirds of the alluvial fan south of Furnace Creek 

Ranch where diverted water was not applied (figs. 9 and 46). 

Infiltration from the Amargosa River downstream of Dumont 

Dunes, California (USGS streamgage 10251375) (fig. 14) 

averaged 720 acre-ft/yr (1.0 ft3/s) and was specified with the 

well package in MODFLOW (Harbaugh, 2005) (fig. 46).

Discharges from high-altitude springs in recharge areas 

were not simulated in the DV3-SS model (fig .46) because the 

springs are perched. Discharge from perched springs is not 

part of the regional groundwater system because infiltrated 

precipitation enters and exits from the perched groundwater 

system. Spring-pool altitudes from perched springs were 

used as measurement observations to constrain the top of the 

simulated water table, which is the uppermost occurrence of 

saturation and includes perched intervals.

Remaining discharges in ET areas not simulated as 

specified discharges were simulated as specified heads 

(fig. 46) because discharge estimates were uncertain and 

reference water levels were needed. Discharges from Franklin 

Lake and Death Valley playa were uncertain relative to watertable altitudes and hydraulic conductivities in these areas 

(table 4). Discharge by ETGW from the northern third of the 

alluvial fan downgradient of Furnace Creek Ranch (fig. 9) was 

simulated with specified heads (fig. 46) because amounts of 

return flow in discharge estimates were unknown. Discharge 

near site AR11 (USGS streamgage 354903116130401) on the 

Amargosa River (fig. 12) was simulated with a specified head 

(fig. 46) for numerical stability and is the functional terminus 

of the PDVS groundwater system. The DV3-SS model 

converged slowly prior to introducing a specified-head cell 

near site AR11 because small differences between specified 

recharge and discharge were not reconciled easily. A flow 

observation near site AR11 assured that simulated discharge 

matched the measured discharge of 1,100 acre-ft/yr.

Simulation of Springs

Conduits between spring pools and the most transmissive 

layer beneath springs were inferred and not simulated, except 

in the Ash Meadows discharge area. Spring discharge was 

specified directly from the most transmissive layer in Indian 

Springs, Pahrump Valley, and the Furnace Creek area (table 9). 

The most transmissive layer coincides with the hydrogeologic 

unit that is the source of spring water, which typically is 

carbonate rock.
86 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 46

Devils Hole 

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Rainier Mine

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pa hranagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Emigrant 

Valley

AD-4

AR-11

Saratoga 

Spring area

Ash Meadows 

discharge area

Furnace Creek 

area

Lower Amargosa area

Franklin 

Well area

Stewart Valley

Pahrump 

Valley

Oasis Valley

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Site used only for measurement observations in steadystate (DV3-SS) model

Site used as boundary 

conditions and measurement 

observations in steady-state 

(DV3-SS) model

Observation well—includes 

Devils Hole site

Spring—spring-pool altitude

Water-table altitude 

comparison to land surface

Specified discharge of spring 

—spring-pool altitude used 

as measurement observation

Specifed discharge of evapotranspiration area—waterlevel altitude used as 

measurement observation

Specified head of evapotranspiration area—discharge 

used as measurement 

Dumont observation

Dunes

Figure 46. Locations and types of boundary conditions and measurement observations used in the Death Valley version 

3 steady-state model (DV3-SS), in the study area, Nevada and California.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 87

Table 9. Springs explicitly simulated in Death Valley version 3 steady-state model (DV3-SS), estimated predevelopment spring discharge, 

and the minimum measured discharge from springs during groundwater development, in the study area, Nevada and California.

[Discharge estimates compiled in Jackson and Halford (2020). Minimum measured discharge during groundwater development: Minimum discharge 

that is less than one-half of predevelopment spring discharge is highlighted in bold. "–" indicates that minimum measured discharge is unknown. 

Abbreviations: acre-ft/yr, acre-feet per year; ft3/s, cubic feet per second; NGVD29, National Geodetic Vertical Datum of 1929]

Discharge 

area Spring name Site identifier Model layer

Pool altitude

(feet above

NGVD29)

Predevelopment 

discharge,

acre-ft/yr (ft3/s)

Minimum measured 

discharge during 

groundwater development,

acre-ft/yr (ft3/s)

Indian Springs Indian Springs 363354115400601 2 3,183 700 (0.96) –

Pahrump Valley Manse Spring 360919115541501 5 2,776 4,350 (6.00) 0 (0.00)

Bennetts Spring 361222115585801 5 2,680 5,430 (7.50) 0 (0.00)

Ash Meadows Five Springs Area 362723116184101 1 2,345 310 (0.43) 0 (0.00)

Purgatory Spring Well 362822116193801 1 2,336 80 (0.11) 10 (0.02)

School Spring 362532116181501 1 2,323 10 (0.01) –

Point of Rocks Spring 362405116161300 1 2,320 620 (0.85) 330 (0.46)

Collins Spring 362450116174001 1 2,320 20 (0.02) 10 (0.01)

King Pool Spring 362407116162401 1 2,314 1,960 (2.70) 1,920 (2.65)

Longstreet Spring 362751116192701 1 2,310 1,090 (1.50) 830 (1.14)

North Scruggs Spring 362601116182800 1 2,305 100 (0.14) 70 (0.10)

South Scruggs Spring 362554116184101 1 2,300 30 (0.04) –

Jack Rabbit Spring 362324116163900 1 2,280 1,010 (1.40) 0 (0.00)

Rogers Spring 362835116192101 1 2,275 940 (1.30) 690 (0.95)

Soda (Bell) Spring 362848116195901 1 2,254 130 (0.18) 0 (0.00)

Fairbanks Spring (AM-1a) 362924116203001 1 2,250 2,750 (3.80) 1,860 (2.57)

Big Spring (AM-8) 362230116162001 1 2,247 1,590 (2.20) 1,160 (1.60)

2 Davis Spring 362401116181102 1 2,245 10 (0.01) –

1 Davis Spring 362401116181101 1 2,243 640 (0.88) –

Cold Spring 362740116204201 1 2,235 120 (0.16) 110 (0.15)

Crystal Pool (AM-5a) 362502116192301 1 2,203 4,750 (6.55) 2,630 (3.63)

Furnace Creek Nevares Springs 363045116491601 2 946 430 (0.60) –

Travertine Springs 362630116494701 2 415 1,380 (1.90) –

Texas Springs 362728116501101 2 397 360 (0.50) –

Furnace Creek Wash sump 362627116494901 2 320 940 (1.30) –

Furnace Creek Wash buried tile 362632116501201 2 265 290 (0.40) –

Furnace Creek Inn tunnel 362709116505201 2 73 220 (0.30) –

Spring discharges from the Ash Meadows discharge area 

were specified from layer 1. Vertical conduits were simulated 

explicitly between spring pools in layer 1 and underlying 

carbonate rocks as high-hydraulic conductivity paths through 

basin fill. These conduits were isolated from surrounding 

basin fill by minimizing cell-by-cell conductances between the 

conduits and adjacent basin fill with horizontal-flow barriers 

(Hsieh and Freckleton, 1993). The approach for simulating 

Ash Meadows springs is consistent with the Laczniak and 

others (1999) conceptual model (fig. 8). The conceptual 

model shows that these springs discharge groundwater from 

underlying carbonate rocks through permeable conduits that 

minimally interact with overlying basin fill prior to entering 

spring pools (fig. 8). The conduits may be permeable travertine 

deposits or lenses of gravels and sands within clay-rich basin 

fill. The precise geometry of the conduits within basin fill is 

unknown because these conduits have not been differentiated 

in hydrogeologic frameworks and previous studies provide 

little guidance on their occurrence and extent. Therefore, 

a simplistic approach was used by simulating conduits as 

vertical, high-hydraulic conductivity paths from carbonate 

rocks to spring pools.

Groundwater Development—DV3-AM-AFFCR 

and DV3-PDVS Models

Groundwater development was simulated so that 

transmissivities, specific yields, and specific storages could be 

estimated in areas where water levels and spring discharges 

have been affected by pumping (fig. 29). The central 

Amargosa Desert, Ash Meadows discharge area, and Pahrump 

Valley are the principal areas affected by groundwater 

development. Groundwater development also was simulated 

in Yucca Mountain and on the NNSS, including Pahute Mesa, 
88 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Buckboard Mesa, Yucca Flat, Frenchman Flat, CP basin, and 

Jackass Flats. Isolated areas of groundwater development were 

simulated to refine hydraulic-property estimates around Indian 

Springs, Emigrant Valley, south of Bullfrog Hills, Beatty, and 

the Furnace Creek area (fig. 29). Water-level fluctuations from 

time-varying (episodic) recharge were not simulated because 

estimating episodic recharge would detract from estimating 

transmissivities and specific yields.

Groundwater development was simulated with two 

models because the PDVS groundwater basin is hydraulically 

isolated from the Ash Meadows, AFFCR, and PMOV 

groundwater basins. Separate models better accommodated 

differences in pumping histories and reduced computational 

time. Pumping from the PDVS groundwater basin began in 

1913, whereas irrigation pumping from the central Amargosa 

Desert began in the 1950s (fig. 30). Groundwater development 

in the central Amargosa Desert, Ash Meadows discharge area, 

Yucca Mountain, the NNSS, and isolated areas was simulated 

with the DV3-AM-AFFCR model. Groundwater development 

in Pahrump Valley was simulated with the DV3-PDVS model.

Temporal Discretization

Temporal discretization of pumping in the DV3-

AM-AFFCR and DV3-PDVS models differed because the 

temporal resolution of groundwater-level and spring-discharge 

measurements differed between groundwater-development 

areas. Groundwater levels and spring discharges were 

measured infrequently in Pahrump Valley during the first 40 

years of pumping and regularly during limited periods after 

1960. Groundwater levels were measured seasonally and 

consistently in the central Amargosa Desert since pumping 

began during the 1950s (fig. 30). Groundwater levels and 

spring discharges were measured frequently in the Ash 

Meadows discharge area during the period when groundwater 

was pumped by Cappaert Enterprises (fig. 39).

Seasonal and monthly pumping were simulated in 

the DV3-AM-AFFCR model so that measured waterlevel changes and spring captures could be matched in the 

central Amargosa Desert and the Ash Meadows discharge 

area. Seasonal pumping was approximated by assuming all 

irrigation pumping occurred between mid-March and midSeptember. Monthly pumping was simulated from 1969 to 

1977, when discharges were measured from the nine pumping 

wells and one injection well in the Ash Meadows discharge 

area near Devils Hole (fig. 38). Pumping from all other water 

uses and return flows were unchanged during each year. This 

included pumping from Indian Springs, Emigrant Valley, 

Yucca Mountain, the NNSS, south of Bullfrog Hills, Beatty, 

and the Furnace Creek area (fig. 29).

Annual pumping was simulated in the DV3-PDVS model 

because pumping, water-level changes, and spring captures 

are relatively uncertain. Pumping estimates are less certain in 

Pahrump Valley, compared to the central Amargosa Desert, 

because about 30 percent of the water in Pahrump Valley 

was pumped prior to crops being inventoried annually. Water 

levels in Jeep Trail and Hwy 127 MM21-1 wells are typical, 

with limited measurements prior to 2000 (fig. 35). Simulating 

seasonal pumping for irrigation is not beneficial to calibration 

without commensurate water-level measurements.

Boundary Conditions

DV3-AM-AFFCR and DV3-PDVS models simulated 

changes from predevelopment conditions and directly 

simulated drawdowns and spring captures. Initial heads 

were all zero, which represented no drawdown relative to 

predevelopment conditions. Discharges from springs and ET 

areas that had been simulated as specified discharges in the 

DV3-SS model were simulated as capture-limited boundaries 

(Halford and Plume, 2011; p. 35) in the DV3-AM-AFFCR and 

DV3-PDVS models (fig. 46).

A capture-limited boundary limits the total capture of 

discharge from springs and ET areas to their predevelopmentdischarge estimates. MODFLOW does not have a boundarycondition package that simulates limited capture. Therefore, 

two MODFLOW packages were combined in each model cell 

where discharge occurs that simulates limited capture. One 

package simulates the injection of water into the model cell, 

whereas the other package simulates the removal of water 

from the model cell. The water injected during each stress 

period is the predevelopment discharge. The water removed 

is controlled by a head-dependent boundary package, such as 

the drain package (Harbaugh, 2005). In the drain package, the 

elevation is equal to the extinction depth and the conductance 

is equal to the predevelopment discharge divided by the 

extinction depth. The extinction depth is the depth below the 

predevelopment water level at which the spring will go dry 

or ET ceases (phreatophytes die). When these packages are 

coupled and the simulated water level at the drain is equal to 

the initial head of zero, indicating the spring is unaffected by 

pumping, then the water injected is equal to the water removed 

and no capture occurs. As the simulated water level declines 

at the drain, the water injected remains the same, but the 

water removed (discharging from spring) decreases, causing 

capture, which is computed as injection minus water removed. 

Once the simulated water level at the drain is at or below the 

extinction depth, no water is removed from the drain and all 

injected water is captured, which equals the predevelopment 

discharge.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 89

Capture-limited boundaries were simulated with a 

combination of the river and drain packages in MODFLOW 

(Harbaugh, 2005). Water was injected with the river package, 

instead of the well package, so that only pumping was 

simulated and tracked with the well package and the river 

package only simulated and tracked the injection component 

of capture when using ZONEBUDGET (Harbaugh, 1990). 

Predevelopment discharges were injected with the river 

package, where riverbed conductance is the predevelopment 

discharge divided by the difference between the river stage 

and river bottom. The river-stage parameter was set equal 

to 1 ft above the river-bottom altitude so that the riverbed 

conductance equaled the predevelopment discharge. River 

stages and bottom altitudes were sufficiently high above the 

top of the model so that the river cells always behaved as 

losing river cells, which allowed simulated river leakage to be 

a constant injection rate. Drain elevations equaled extinction 

depths and conductances equaled predevelopment-discharge 

rates divided by extinction depths. Differences between 

injected and drained water simulated limited groundwater 

capture, meaning that simulated captures cannot exceed 

measured discharges.

Extinction depths were estimated in Pahrump Valley and 

the Ash Meadows discharge area because spring discharges 

had been captured (table 9). Springs such as Bennetts and 

Manse Springs in Pahrump Valley and Jack Rabbit Spring, 

Five Springs Area, and Soda (Bell) Spring in the Ash 

Meadows discharge area had to be simulated as capturelimited because all springs ceased flowing in response to 

nearby pumping. Extinction depths were estimable in these 

springs and a dozen others because declines in discharge had 

been measured (table 9). A uniform extinction depth of 5 ft 

was assumed for all other discharges by springs and ET areas.

Discharges from ET areas that had been simulated 

as specified heads in the DV3-SS model (fig. 46) were 

simulated as specified heads of 0 ft in the DV3-AM-AFFCR 

and DV3-PDVS models. These specified heads simulated 

unconstrained no-drawdown boundaries in Franklin Lake, 

Death Valley playa, and near site AR11 (USGS streamgage 

354903116130401) on the Amargosa River (fig. 46). These 

specified heads were not converted to capture-limited 

boundaries because capture never exceeded 80 acre-ft/yr 

relative to simulated predevelopment discharges of 1,840 

acre-ft/yr from specified heads in the DV3-SS model.

Well ER-6-1-2 main Multiple-Well Aquifer Test—

DV3-ER612 Model

A large-scale, multiple-well aquifer test (MWAT) was 

simulated with the DV3-ER612 model to better constrain 

transmissivity, specific yields, and specific storages in the 

shallow carbonate aquifer. A separate stress-response model, 

DV3-ER612, was used to simulate the well ER-6-1-2 main

MWAT, instead of using either the DV3-AM-AFFCR or 

DV3-PDVS models, because finer temporal discretization 

is required to adequately simulate drawdown responses to 

pumping. Well ER-6-1-2 main was pumped and drawdowns 

were estimated in 13 observation wells that were 0–33 

mi from the pumping well. Drawdowns were detected in 

observation wells, open to carbonate rocks, as far away as 

33 mi from the pumping well (Jackson and Halford, 2019). 

Detected drawdowns are within an irregular 5 × 50-mi 

corridor of carbonate rocks between northern Yucca Flat and 

the Ash Meadows discharge area (fig. 47).

Drawdowns from pumping in well ER-6-1-2 main were 

estimated from measured water-level data in 13 observation 

wells (Jackson and Halford, 2019). Drawdowns were not 

equivalent to measured water levels because natural waterlevel fluctuations, such as barometric pressure and Earth 

tides, masked water-level changes from well ER-6-1-2 main

pumping. Water levels were measured continuously in 

pumping well ER-6-1-2 main and eight observation wells: 

(1) ER-3-1-2 (shallow); (2) ER-6-1 main (lower zone); 

(3) ER-6-1 main (upper zone); (4) ER-6-1-1; (5) ER-6-1-2 

piezometer; (6) ER-7-1; (7) UE-1h; and (8) Tracer Well 3

(fig. 47). Drawdowns in these wells were differentiated 

from natural fluctuations and effects of other pumping wells 

with water-level models (Halford and others, 2012). Water 

levels were measured periodically with tape downs in five 

additional wells: (1) Army 1 WW; (2) U-3cn 5; (3) UE-7nS; 

(4) UE-10j (2232-2297 ft); and (5) WW-2 (3422 ft) (fig. 47). 

All drawdown analyses are reported in Jackson and Halford 

(2019).

Temporal Discretization

Well ER-6-1-2 main pumped 75 million gal (230 acre-ft) 

from February 5 to July 23, 2004, during a MWAT and tracer 

test in southern Yucca Flat (Stoller-Navarro Joint Venture, 

2005a). Well development, step-drawdown tests, and a 

preliminary 9-day constant-rate test occurred during February 

5–21, 2004. The 90-day constant-rate test occurred during 

April 24–July 23, 2004, when well ER-6-1-2 main pumped 

64 million gal at 524 gal/min (Stoller-Navarro Joint Venture, 

2005a). Pumping was deliberately ceased during July 8–12, 

2004, which introduced a calibration point for tracer transport 

analyses (Stoller-Navarro Joint Venture, 2005a).

Stress periods in the DV3-ER612 model matched the 

periods of well development, step-drawdown testing, constantrate pumping, and the 4-day shut-off because these pumping 

changes clearly were observed in drawdowns (Jackson and 

Halford, 2019). Seasonal or annual stress periods used in the 

DV3-AM-AFFCR and DV3-PDVS models, respectively, 

would not have been adequate to simulate these responses.
90 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 47

95

95

373

190

Mercury Amargosa Valley

CALIFORNIA

NEVADA

LINCOLN

CLARK

NYE

INYO

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

PAHRUMP TO 

DEATH VALLEY

SOUTH

Pahute

Mesa

Belted Range

Spring Mountains

Groom

Range

Pintwater Range

Specter Range

Halfpint Range

Halfpint Range

Spotted Range

Eleana Range

Yucca

Flat

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Amargosa

Desert

Emigrant 

Valley

Quartzite 

Ridge

CP 

Hills

Skull 

Mountain

Mine 

Mountain

Syncline Ridge

Emigrant 

Valley

Mid 

Valley

Ash Meadows 

discharge

area

Devils

Hole

Army 1 WW

Tracer Well 3

ER-3-1-2 

(shallow)

UE-1h

UE-10j (2232-2297 ft)

WW-2 (3422 ft)

ER-7-1

UE-7nS

U-3cn 5

ER-4-1 m1

WW-C-1

210 feet

167 feet

50 feet

ER-6-1-2 main 

ER-6-1 main (lower zone)

ER-6-1 main (upper zone)

ER-6-1-1

ER-6-1-2 piezometer

0 10 MILES

0 5

5

10 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°

37°

36°

30'

115°30'

Map area

Study 

area

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Spring

Area of discharge by evapotranspiration

Pumping well

Observation well

Site, not used in well 

ER-6-1-2 multiple-well 

aquifer test analysis

Figure 47. Observation wells monitored during well ER-6-1-2 main multiple-well aquifer test, in the study area, Nevada 

and California.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 91

Boundary Conditions

Pumping in well ER-6-1-2 main was simulated using the 

well package in MODFLOW (Harbaugh, 2005). Groundwater 

discharge from springs and ET areas (fig. 46) were simulated 

in the DV3-ER612 model as capture-limited boundaries, using 

the same method described for use in the DV3-AM-AFFCR 

and DV3-PDVS models.

Calibration

Hydraulic-conductivity, specific-yield, specific-storage, 

and recharge distributions, and spring-extinction depths 

in the Ash Meadows discharge area were estimated by 

minimizing a weighted composite, sum-of-squares objective 

function. Hydraulic-property and recharge distributions were 

defined with 3,415 pilot points, where about 60 percent of 

the parameters were adjusted with PEST (Doherty, 2010a). 

Differences between measured observations and simulated 

responses formally defined the goodness-of-fit or improvement 

of calibration. This formal definition also was informed 

by qualitative assessment of estimated hydraulic-property 

distributions and biases in residuals.

Stress responses were simulated with the integrated DV3 

model, which was called by PEST (fig. 48). The DV3 model 

initially translated estimated hydraulic conductivities, specific 

yields, specific storages, and recharge rates at pilot points 

into two-dimensional MODFLOW arrays. Stress-response 

models were executed sequentially, where each model used 

the same hydraulic-property arrays stored in a common 

directory (fig. 48). Simulated responses from all four stressresponse models were compared to measured observations. 

Results from all models simultaneously informed PEST, 

and parameter changes were estimated iteratively until the 

objective function had been minimized, resulting in calibration 

of the DV3 model. The objective function was informed by 

measurement and regularization observations.

The objective function defines misfit between measured 

data and simulated equivalents so that parameters can 

be changed to minimize this misfit. Data used to inform 

parameters are measurement observations. Adjustable 

parameters include hydraulic conductivities, specific yields, 

specific storages, recharge rates, and spring-extinction depths. 

Parameters are estimable at pilot points in areas where 

simulated results are sensitive to parameter changes and data 

exist to judge goodness of fit. However, parameter estimation 

is not effective at pilot points where no data are available.

Regularization informs the objective function of 

conceptual models for parameters relatively insensitive 

to measurement observations. Tikhonov regularization 

provides information in the form of either preferred values 

of parameters or preferred relations between parameters 

(Doherty, 2010a). These preferred values or relations are 

regularization observations, which are added as prior 

information to the PEST control file (Doherty, 2010a). 

A hypothetical example of a preferred condition is the 

assumption of a homogeneous transmissivity of 1,000 ft2

/d 

in a hydrogeologic unit. For each hydraulic-conductivity 

pilot point in the hydrogeologic unit, the regularization 

observation would be the transmissivity (1,000 ft2/d) divided 

by the hydrogeologic unit thickness. During calibration with 

PEST, measurement and regularization objective functions 

are minimized simultaneously by allowing measurement 

observations to inform parameters where data exist and 

regularization observations (preferred conditions) to inform 

parameters where measured observations are deficient.

Measurement Observations

Measured observations characterized predevelopment 

flow and pumping effects. Water-level altitudes, water-level 

differences between wells, transmissivities, and discharge 

rates characterized predevelopment flow (table 10). Measured 

water-level altitudes included groundwater levels in wells, 

spring-pool altitudes, water levels in ET areas, and water-table 

altitude comparisons to land surface. Water-level differences 

between wells, including water-level differences between 

wells and spring pools in the Ash Meadows discharge area, 

constrained vertical and lateral hydraulic gradients. Simulated 

transmissivities were compared to transmissivities estimated 

from aquifer tests and specific capacities. Predevelopment 

discharges primarily informed the objective function of 

conceptual preferences, such as flows across groundwaterbasin boundaries, because most measured discharges were 

specified in the DV3-SS model. Water-level changes and 

spring captures characterized pumping effects. Waterlevel changes principally were responses to groundwater 

development, but also included drawdown from the well 

ER-6-1-2 main MWAT. Spring captures primarily were 

responses to pumping from Cappaert Enterprises in the Ash 

Meadows discharge area.

Groundwater levels, spring-pool altitudes, and 

transmissivities were measured at 1,409 unique sites in 

the study area (Jackson and Halford, 2020). Water levels 

were measured in 1,070 wells and 164 spring pools, with 

predevelopment levels available for 881 wells and 162 spring 

pools (table 10). Transmissivities were estimated from aquifer 

tests and specific capacities in 271 wells, with less than 40 

percent of these wells also supplying water-level data. Site 

identifier, station name, location, and observation group for 

each unique site are reported in Jackson and Halford (2020).
92 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig48

MASTER

—Content————

Pilot points with K, SS, SY, & N values

Regularization

Calibration instructions

—Actions ————

Write pilot points with K, SS, SY, & N values

Execute stress-response models

Compare simulated to measured

Revise K, SS, SY, & N estimates

Inspect Results

Mapped T, S, & N

Residuals

Water-level profiles

Discharges

Hydrographs

Scatter plots

Initiate PEST

Calibrated?

YES

NO

Build Arrays

—Content—

Pre-processing files

—Actions —

Get pilot points from MASTER

Convert pilot points to arrays

Stress-Response Models

PEST, Parameter ESTimation

PEST controls

DV3-ER612 model

 — Content — 

Observations

Post-processing files

MODFLOW model

— Actions — 

Execute MODFLOW model

Sample simulated results

DV3-PDVS model 

— Content — 

Observations

Post-processing files

MODFLOW model

— Actions — 

Execute MODFLOW model

Sample simulated results

DV3-AM-AFFCR model 

— Content — 

Observations

Post-processing files

MODFLOW model

— Actions — 

Execute MODFLOW model

Sample simulated results

DV3-SS model 

— Content — 

Observations

Post-processing files

MODFLOW model

— Actions — 

Execute MODFLOW model

Sample simulated results

Figure 48. Model-run process of the Death Valley version 3 model (DV3), which is an integrated stress-response 

model, in the study area, Nevada and California. DV3-AM-AFFCR, Death Valley version 3 model simulating groundwater 

development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, and Pahute Mesa–Oasis Valley groundwater 

basins; DV3-ER612, Death Valley version 3 model simulating pumping during the ER-6-1-2 main multiple-well aquifer 

test; DV3-PDVS, Death Valley version 3 model simulating groundwater development in the Pahrump to Death Valley 

South groundwater basin; DV3-SS, Death Valley version 3 steady-state model; K, hydraulic conductivity; N, recharge; S, 

storativity; Ss, specific storage; SY, specific yield; and T, transmissivity.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 93

Table 10. Summary of observations and Death Valley version 3 model (DV3) fit to simulated comparisons, in the study area, Nevada 

and California.

[Model: DV3-SS, Death Valley version 3 stress-response model simulating steady-state (predevelopment) conditions; DV3-AM-AFFCR, Death Valley version 3 

stress-response model simulating groundwater development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, and Pahute Mesa–Oasis Valley groundwater 

basins; DV3-PDVS, Death Valley version 3 stress-response model simulating groundwater development in the Pahrump to Death Valley South groundwater 

basin; DV3,ER612, Death Valley version 3 stress-response model simulating pumping during the well ER-6-1-2 main multiple-well aquifer test. Sum-ofweights squared: (ft/ft)2

, foot per foot squared; [ft/log(ft2/d)]2, square of foot per log of square foot per day; (ft/acre-ft/yr)2, foot per acre-foot per year squared; 

[ft/(gal/min)]2, foot per gallon per minute squared. RMS error: Root-mean-square error; ft, foot; log(ft2/d), log of square foot per day; acre-ft/yr, acre-foot per 

year; gal/min, gallon per minute; ft3/s, cubic foot per second. Abbreviation: NA, not applicable]

Model Observation group Number of 

observations

Sum of squares of

weighted residuals

(foot squared)

Sum-of-weights 

squared RMS error

DV3-SS Water-level altitude in wells 881 2,005,251 9.E+2 (ft/ft)2 49 ft

Water-level altitude in evapotranspiration areas 1,657 20,027 2.E+1 (ft/ft)2 35 ft

Spring-pool altitude 162 114,580 3.E+1 (ft/ft)2 64 ft

Water-table altitude comparison to land surface 1,675 14,001 4.E+0 (ft/ft)2 58 ft

Water-level difference between sites 50 79,755 6.E+2 (ft/ft)2 12 ft

Transmissivity from aquifer tests 142 70,643 2.E+5 [ft/log(ft2/d)]2 0.6 log(ft2/d)

Transmissivity from specific capacities 129 57,367 8.E+4 [ft/log(ft2/d)]2 0.9 log(ft2/d)

Water budget volumes 23 169,317 1.E-2 (ft/acre-ft/yr)2 30 acre-ft/yr

Conceptual recharge volumes 31 546,236 3.E-3 (ft/acre-ft/yr)2 110 acre-ft/yr

Erroneous recharge from specified heads 3 1,475 7.E-6 (ft/acre-ft/yr)2 120 acre-ft/yr

DV3-AMAFFCR

Amargosa Desert drawdown 3,782 1,700,713 2.E+7 (ft/ft)2 0.31 ft

Ash Meadows drawdown 1,030 528,764 5.E+6 (ft/ft)2 0.32 ft

Drawdown from localized pumping centers 1,572 4,228 8.E+3 (ft/ft)2 0.7 ft

Ash Meadows spring capture 510 723,563 4.E+1 [ft/(gal/min)]2 140 gal/min (0.3 ft3/s)

DV3-PDVS PDVS drawdown 1,626 1,968,409 2.E+7 (ft/ft)2 0.3 ft

Pahrump Valley spring capture 203 79,419 8.E+4 (ft/ft3/s)2 1.0 ft3/s (444 gal/min)

DV3-ER612 Well ER-6-1-2 main drawdown 1,514 498,180 1.E+9 (ft/ft)2 0.02 ft

Totals 14,990 8,581,929 NA NA

Many more observations exist than unique sites primarily 

because water levels and discharges have been measured 

many times in wells and springs. About 11,600 observations 

from wells and springs are compared in the objective function 

(table 10), which is nearly 10 times greater than the number of 

unique sites. Water-level changes (drawdowns) and springdischarge changes (capture) resulting from pumping were 

compared to simulated equivalents for more than 60,000 

observations, but only about 10,000 observations had weights 

greater than 0 (table 10). More than 60,000 observations 

are reported by PEST because simulated hydrographs were 

sampled continuously regardless of measurement frequency. 

For example, well Jeep Trail has 15 water-level measurements 

from 1959 to 2015, but includes an additional 107 sampling 

observations (1 for each year from 1913 to 2018) to view a 

continuous simulated hydrograph from 1913 to 2018. These 

additional sampling observations were given weights of 0 

and, therefore, did not affect the objective function. More 

observations than unique sites also exist because multiple 

observations—such as a water-level altitude and water-level 

changes—were measured in a well. For example, 

Tracer Well 3 has four types of observations: (1) waterlevel altitude; (2) water-level changes from groundwater 

development; (3) drawdowns from the well ER-6-1-2 main

MWAT; and (4) a transmissivity estimate.

Simulated water levels were sampled from a single 

MODFLOW layer for comparison to measured water-level 

altitudes and changes. Open intervals are less than 246 ft 

(75 m) in length for 63 percent of the wells, which functionally 

precludes assigning more than a single MODFLOW layer. 

Open intervals penetrating multiple MODFLOW layers were 

assigned to the most transmissive layer, as conceptualized in 

the hydrogeologic framework. This is because water levels 

in wells most closely represent water levels in the most 

transmissive interval of a formation. Less than 17 percent of 

1,070 wells fully penetrated multiple MODFLOW layers and 

were assigned to the most transmissive layer.
94 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Simulated water levels at wells and springs were 

interpolated laterally between model cell centers in assigned 

layers, except where hydraulic discontinuities made lateral 

interpolation inappropriate. Simulated water levels mostly 

were interpolated from nodes of surrounding cells to points 

of measurement with MOD2OBS (Doherty, 2010b). Well 

locations of a small number of wells were shifted from their 

true locations to the model cell centers in MOD2OBS input 

files and the shifted locations are shown in spatial coverages 

of model results (Jackson and Halford, 2020). For example, 

instead of discretizing the model grid finer, locations of Devils 

Hole and Devils Hole Well (AM-5) were manually shifted from 

their true locations to attenuate the effect of an intervening 

discontinuity in shallow carbonate rocks on simulated water 

levels. This shift was an approximate difference of 400 ft west 

and 400 ft east from the true locations of Devils Hole and 

Devils Hole Well (AM-5), respectively. Simulated spring pools 

in the Ash Meadows discharge area were sampled from cell 

centers because their conduits from carbonate rocks to land 

surface were simulated explicitly, and spring-pool cells were 

isolated hydraulically from adjoining cells.

Weights were assigned to observations to represent 

expected observation accuracy and importance of each 

observation to model fit. For example, water-level altitude 

observations were weighted progressively less as observations 

were more uncertain, which resulted in water levels in wells 

being weighted more than water levels in ET areas. Weights 

accounted for differences in the number of observations 

between wells, where a well with 100 water levels will be 

weighted more than a well with 10 water levels if all water 

levels are weighted equally. Weights also accounted for the 

range of measurement values between observation groups. For 

example, log-transmissivities from 142 aquifer-tests ranged 

from -4.7 to 5.6 log(ft2/d), whereas water-level altitudes in 

881 wells ranged from -281 to 8,504 ft above NGVD29. 

Transmissivity observations would not affect calibration if logtransmissivities from aquifer-tests and water-level altitudes in 

wells were weighted equally.

Weights were adjusted iteratively so all observation 

groups affected model calibration. Mismatches in scatter 

plots of water-level altitudes and transmissivities, 

spatial distributions of water-level residuals, profiles of 

predevelopment water levels, and hydrographs of waterlevel changes and spring captures directly informed relative 

importance of observation groups on model calibration. 

Simulated water levels; drawdown extents; and transmissivity, 

specific-yield, specific-storage, and recharge distributions 

were examined for conceptual inconsistencies. For example, 

transmissivities exceeding 1,000 ft2

/d in low-permeability 

rocks are conceptually problematic. This problem typically 

identified a misclassified hydrogeologic unit, a compensating 

error, or an insensitive parameter that drifted to an upper limit. 

Influence of each observation group on calibration was best 

summarized by sum-of-squares (table 10). This was because 

the weighted sum-of-squares residuals for each observation 

group integrates the number of observations, range of 

measurement values, and relative weighting.

Predevelopment Observations—DV3-SS Model

Measurement observations used in the calibration of 

the DV3-SS model were categorized into 10 observation 

groups (table 10). The following sections describe: (1) the 

different types of measurement observations; (2) methods used 

to estimate observations, where appropriate; (3) reasoning 

for weight assignment during calibration; and (4) how 

measurements were implemented in the DV3-SS model and 

used in model calibration.

Water-Level Altitudes in Wells

Measured and simulated water-level altitudes were 

compared from 1,033 wells (fig. 46) in the study area, where 

881 wells have weights greater than 1 × 10-6 (table 10). Most 

measured water levels were relatively shallow, with 961 

wells being screened in layers 2, 3, or 4. Only 26 wells were 

screened in layer 6, 80 percent of which were in the NNSS. 

Small weights were assigned to water levels in 152 wells, 

which limited sensitivity of comparisons between measured 

and simulated water levels during parameter estimation. 

Small weights were assigned because water levels either were 

redundant or were affected by transient (nuclear testing or 

pumping) conditions. These water-level observations were 

assigned small weights, rather than excluded from the DV3 

model, because these data provided censored information 

during calibration. For example, if a measured water level is 

affected by pumping, then the simulated predevelopment water 

level should be higher.

Water-Level Altitudes in Evapotranspiration Areas

Water-level altitudes were estimated at 1,657 ET 

locations (fig. 46; table 10) and compared to water levels 

simulated with the DV3-SS model. Water levels are within 30 

ft of land surface in discharge areas. Water levels exceed land 

surface at spring pools and remain below land surface in ET 

areas. Water levels in ET locations were estimated with landsurface altitudes from a digital elevation model (DEM) that 

sampled 1:24,000-scale maps every 30 m and reported to the 

nearest whole meter (Gesch and others, 2009). DEM altitudes 

typically spanned 10 ft in model cells where discharge by 

ETGW occurred. Water levels were assumed equal to average 

land-surface altitudes because variability of land surface 

exceeds measured differences between land surface and water 

levels. These observations are less certain than measured 

water-level altitudes in wells and were weighted less. During 

DV3-SS model calibration, if measured water-level data from 

wells exist in the discharge area, the measured water-level 

data have greater weights than DEM-averaged water levels 

in ET locations and parameters have greater sensitivity to the 

measured data.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 95

Spring-Pool Altitudes

Measured and simulated spring-pool altitudes were 

compared from 162 springs in the study area (table 10). 

Altitudes were well known for 27 springs where discharges 

were simulated (table 9). Altitudes of springs in the Eleana 

Range, Groom Range, Sheep Range, Spring Mountains, 

and Black Mountains were less certain because altitudes 

were estimated from the DEM used to calculate water-level 

altitudes in ET areas. Spring altitudes estimated from the DEM 

were weighted less than springs where altitudes were known. 

Despite the low weight assigned to DEM-estimated spring 

altitudes, water-table altitudes in mountain ranges depended 

on these spring-pool altitudes because wells were absent 

(figs. 6 and 46).

Water-Table Altitude Comparisons to Land Surface

Simulated water-table altitudes were compared to landsurface altitudes to ensure that the simulated water table 

remained below land surface. Land-surface altitudes were 

sampled at 1,675 locations from the DEM used to calculate 

water-level altitudes in ET areas. Water-table altitudes were 

evaluated after each MODFLOW simulation and simulated 

altitudes either remained unchanged or were assigned to the 

land-surface altitude. The simulated water-table altitude was 

set equal to the land-surface altitude if the simulated water 

table was below land surface so that the residual equaled zero 

and did not affect model calibration. For example, a simulated 

water-table altitude that initially equaled 4,500 ft would be 

changed to 5,000 ft, where land-surface altitude is 5,000 ft, 

and the residual would be 0 ft. Alternatively, a simulated 

water-table altitude that initially equaled 5,500 ft at the same 

location would not be changed and the residual would be 500 

ft. Water-table altitude comparisons to land surface had small 

weights because these observations are highly non-linear. 

Water-table altitude comparisons also had small weights, 

compared to water-level altitudes in wells and spring-pool 

altitudes, so that calibration was sensitive to measured water 

levels.

Water-Level Differences Between Measurement Sites

Measured and simulated water-level differences between 

wells (or between wells and spring pools) were compared to 

preserve vertical and lateral differences (fig. 49). Water-level 

differences between volcanic rocks at the water table and 

underlying low-permeability carbonate rocks beneath Rainier 

Mesa were the primary vertical differences of concern. The 

greatest vertical difference exceeded 1,800 ft between wells 

ER-12-3 piezometer and ER-12-3 main in Rainier Mesa. Small 

water-level differences in shallow carbonate rocks between 

Yucca Flat and the Ash Meadows discharge area were the 

primary lateral differences of concern. Water levels decline 

32 ft between well ER-6-1-2 main and Devils Hole and are 

separated by 42 mi (fig.49).

Transmissivity Comparisons

Transmissivity estimates from aquifer-test results 

and specific capacities were compared to simulated 

transmissivities. Simulated transmissivities were computed 

by defining the area investigated by each aquifer test (fig. 50), 

averaging hydraulic conductivities of all model cells that 

occur within the area investigated, and then multiplying 

by the contributing thickness (Halford, 2016). The area 

investigated was defined where drawdowns exceeded 0.07 ft 

at the end of each aquifer test, but the radius of investigation 

was not allowed to exceed 6,600 ft. For aquifer tests where 

transmissivity was less than 1,000 ft2/d or small volumes of 

water were pumped, the contributing thickness was limited to 

the well screen length. For aquifer tests where transmissivity 

exceeded 1,000 ft2/d or large volumes (more than 100,000 

gal) of water were pumped (Halford and others, 2006), the 

contributing thickness was the aquifer thickness from the 

DV3 hydrogeologic framework model. If the area investigated 

spanned multiple model layers, the simulated transmissivity 

was computed by averaging hydraulic conductivities in each 

model layer, multiplying by their respective model layer 

thicknesses, and then summing layer-averaged transmissivities 

(Halford, 2016, p. 10). Estimated transmissivities from aquifer 

tests and specific capacities are discussed herein as measured 

transmissivities for comparison to simulated transmissivities 

from the DV3-SS model.

Conceptual Preferences of Recharge, Predevelopment 

Discharge, and Groundwater-Basin-Boundary Flows

Expected and simulated groundwater-flow rates that 

were compared included recharge to groundwater basins, 

flow across divides between groundwater basins, interbasin 

flow through corridors between groundwater basins, and 

discharges from specified heads (table 11). Expected recharge 

to groundwater basins was the annual volume from the 

conceptual recharge distribution (fig. 16), which was estimated 

from predevelopment discharge. No flow was expected 

across boundaries that form divides between groundwater 

basins. Expected interbasin flows through corridors between 

groundwater basins were derived from Darcy estimates 

(fig. 6). Expected discharges from specified heads primarily 

are maximum estimated discharges from playas (table 11). 

Discharge south of Tecopa is an exception where a discharge 

of 1,100 acre-ft/yr was known, but simulated with a single, 

specified head for numerical stability. Simulated flow rates 

were sampled from the DV3-SS model with ZONEBUDGET 

(Harbaugh, 1990).
96 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 49

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373 190

127

318

375

582

AD-4

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

WW-C-1

ER-6-1-2 main

ER-7-1

WW-2 (3422 ft)

UE-10j (2232-2297 ft)

Spring Meadows 12

Spring Meadows 4

GF-2B deep (AM-11)

Fairbanks Spring

Tracer Army 1 WW Well 3

USAF R65N

SM-23-1

Devils Hole

Crystal Pool

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Observation of water-level 

difference between wells

Lateral pair

Vertical pair

Observation well or site

Spring Dumont

Dunes

Figure 49. Lateral and vertical water-level difference observations used in the Death Valley version 3 steady-state 

model (DV3-SS), in the study area, Nevada and California.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 97

sac19-4233_fig 50

Devils Hole 

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

AD-4

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Emigrant 

Valley

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Observation well or site

Transmissivity observation 

—Transmissivity estimate 

from aquifer test. Circle 

size indicates approximate 

area investigated by 

aquifer test.

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

Figure 50. Transmissivity observations from aquifer tests and specific capacities, in the study area, Nevada and 

California.
98 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Table 11. Expected and simulated groundwater-flow rate observations, in the study area, Nevada and California.

[Groundwater basin: AFFCR, Alkali Flat–Furnace Creek Ranch; PDVS, Pahrump to Death Valley South; PMOV, Pahute Mesa–Oasis 

Valley. Flow volume component: Recharge and discharge flow volume components are colored blue and red, respectively. Symbol: <, 

less than.]

Groundwater 

basin Flow volume component Flow volume (acre-feet per year)

Expected Simulated

PMOV Recharge to PMOV 6,000 5,900

Divide between PMOV and Ash Meadows 0 20

Divide between AFFCR and PMOV 0 230

Interbasin flow from PMOV to AFFCR 100 110

Recharge to Bullfrog Hills 100 80

Interbasin flow from Bullfrog Hills to PMOV 100 60

Ash 

Meadows

Recharge to Ash Meadows 21,100 21,600

Divide between Ash Meadows and AFFCR north of well AD-4 0 50

Interbasin flow from Ash Meadows to AFFCR near well AD-4 2,000–4,000 2,550

Leakage from Ash Meadows to AFFCR south of well AD-4 200 270

Divide between Ash Meadows and PDVS 0 70

AFFCR Recharge to AFFCR 4,800 4,850

Divide between AFFCR and PDVS 0 20

Interbasin flow from AFFCR to PDVS near Eagle Mountain <300 60

Discharge from Franklin Lake <700 440

Discharge from specified heads on alluvial fan in Furnace Creek area <300 300

Discharge from floor of Death Valley in AFFCR <200 120

PDVS Recharge to PDVS 22,100 22,200

Interbasin flow from PDVS to Ash Meadows north of Stewart Valley <200 180

Discharge from specified head south of Tecopa 1,100 1,000

Discharge from Saratoga Spring area 800–1,100 950

Discharge from floor of Death Valley in PDVS <200 40

Expected annual volumes from the conceptual recharge 

distribution were divided into 31 zones (fig. 16) and compared 

to simulated annual volumes. Zones were small enough 

that the objective function was informed of expected spatial 

variability in annual volumes of recharge. Zones were large 

enough that annual volumes of recharge were minimally 

affected by displacement of infiltration by low-permeability 

rocks and delineation of zones. Four zones in Pahute Mesa, 

Sheep Range, and Spring Mountains generated more than 

70 percent of all recharge. Annual volumes of recharge were 

limited elsewhere and less than 500 acre-ft/yr in 17 of 31 

zones.

Penalizing simulated water-table altitudes higher than 

land surface (table 10), minimizing flow across groundwaterbasin boundaries (table 11), and matching water-budget 

volumes were conceptual observations (table 11). These 

conceptual observations, which defined well-understood terms 

that were quantified poorly through other observation groups, 

were compared as measurement observations in the objective 

function. Conceptual observations were weighted minimally 

because expected values are uncertain.

Groundwater-Development Observations—DV3-AMAFFCR and DV3-PDVS Models

Measurement observations used in the calibration of the 

DV3-AM-AFFCR and DV3-PDVS models were categorized 

into observation groups of water-level changes and captures 

(table 10). The following sections describe how (1) waterlevel change measurement observations were computed, 

implemented in groundwater-development models, and used 

in model calibration; (2) long-term natural fluctuations from 

variations in recharge were accounted for or removed from 

measured water-level changes; and (3) groundwater captures 

were computed in the groundwater-development models.

Water-Level Changes

Measurement times and water levels were averaged to a 

single value for each stress period prior to estimating waterlevel changes. Water levels were averaged in a total of 308 

wells for the DV3-AM-AFFCR and DV3-PDVS models. For 

modeling purposes, each of the averages is referred to as a 

“measured water level”. Averaging eliminated high-frequency 

fluctuations that were not simulated. For example, water levels 

in well ESB1 were averaged annually because 1-year stress 

periods were simulated in the DV3-PDVS model (fig. 51). 

Simulated water-level changes in well ESB1 were fit to 

changes in these annually averaged water levels.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 99

Measured and simulated water-level changes were 

compared relative to a reference water level in each well 

(fig. 52). Reference water levels established a time when 

simulated water levels were set equal to measured water 

levels. Simulated changes were relative to the reference 

water level and pivoted about the reference water level. This 

occurred during calibration as transmissivities, specific yields, 

and specific storages were estimated (fig. 52). Reference 

water levels were necessary because most water-level records 

began 10–50 years after groundwater development started and 

changes from predevelopment water levels generally were 

unknown. This approach has been applied previously to negate 

unknown effects of entry losses in pumping wells (Halford and 

Yobbi, 2006).

Reference water levels were established so that measured 

water-level changes from pumping primarily were compared. 

Initial water levels commonly were not used because these 

measurements frequently are from well logs and do not 

represent equilibrated conditions after drilling. Water levels 

that have not equilibrated in low-permeability rocks or are 

affected by crustal deformation from earthquakes also were 

not used as reference water levels and were assigned small 

weights. For example, water levels in well Travertine Point 

1 were affected by the Landers earthquake in 1992 (Fenelon 

and Moreo, 2002). A 2005 water level was the reference and 

water levels prior to 1997 were not compared in the objective 

function (fig. 52). Reference water levels also were established 

during the last 10 years of record, after pumping had ceased, 

to mitigate effects of pumping in supply wells such as 

Army 1 WW and WW-8.

Accounting for Temporal Variability in Recharge

Time-varying recharge was not simulated in the DV3 

model because of the complexity of the groundwater system. 

The behavior of rising water-level trends from recharge is 

dependent on annual variations in precipitation, distance from 

the recharge source, unsaturated zone depth, and the hydraulic 

conductivity of unsaturated and saturated rocks. Instead of 

simulating time-varying recharge to account for rising waterlevel trends, the recharge component of the water-level trend 

was differentiated from the pumping component at selected 

sites using water-level models (Halford and others, 2012).

Long-term natural fluctuations from variations in 

recharge were removed from measured water-level changes in 

Devils Hole and nearby wells because they were substantial 

relative to pumping effects. This was most apparent from 

1990 to 2018 when episodic recharge affected water levels in 

Devils Hole more than pumping (fig. 40). Long-term waterlevel fluctuations from recharge estimated in Devils Hole were 

assumed pervasive throughout the shallow carbonate because 

other nearby wells had water-level trends similar to Devils 

Hole. Therefore, long-term recharge trends also were removed 

from wells AD-8, Point of Rocks North (AM-6), Point of Rocks 

South (AM-7), Devils Hole Well (AM-5), North Crystal Well,

SM-23-1, Spring Meadows 12, Spring Meadows 9, Tracer Well 

3 (AD-6), and TW-5 (RV-1) (fig. 53).

Wells along the periphery of pumping centers with small 

rising water-level trends are affected by episodic recharge and 

minimally are affected by pumping, if at all. These water-level 

rises have been attributed to recharge from multiple waterlevel trend studies (Elliott and Fenelon, 2010; Fenelon and 

Moreo, 2002; Fenelon and others, 2012; Jackson and Fenelon, 

2018). Water levels typically have risen about 0.8 ft per decade 

since the 1980s in wells along the periphery of pumping 

centers, such as well CF2 (fig. 32). Small water-level rises 

in these wells may have masked small water-level declines 

from pumping. Because water levels in these wells are rising 

and the magnitude of water-level declines from pumping is 

unknown, recharge could not be differentiated from pumping. 

Instead, measured and simulated water-level changes were 

inspected visually in wells with rising water levels, such as 

well USFWS DR-1 (fig. 18), to determine whether pumping 

likely has been masked by rising trends. Observations from 51 

wells with rising trends were weighted near zero, where the 

rising trend enforces a minimal drawdown boundary at these 

wells.

Measured water-level changes were assumed to be from 

pumping exclusively for wells within the main pumping 

centers. The pumping-only assumption likely was adequate 

where water-level declines exceeded 1 ft per decade, which 

includes most wells in the central Amargosa Desert and all 109 

wells in the PDVS groundwater basin. The only exceptions 

were water levels in Devils Hole and in nearby wells open to 

shallow carbonate rocks.

Groundwater Capture from Springs and Evapotranspiration 

Areas

Measured and simulated captures were compared at 18 

springs in the Ash Meadows discharge area and two springs 

in Pahrump Valley (table 9). Limited capture was simulated 

by combining the river and drain packages in MODFLOW 

(Harbaugh, 2005). Simulated captures were computed by 

subtracting the predevelopment discharge injected in the 

river package from the water removed in the drain package. 

Simulated flow rates from the river and drain packages were 

extracted with a variation of ZONEBUDGET (Harbaugh, 

1990) to compute capture. Simulated capture could not be 

computed directly from ZONEBUDGET because only flows 

across zone faces and flows from individual MODFLOW 

packages for each zone are reported in ZONEBUDGET, and 

rates from multiple packages are not combined. The modified 

program, MOD2BUD, was used to compute capture by 

reading the output file from ZONEBUDGET. MOD2BUD 

sums rates from multiple packages, converts units, interpolates 

rates between time steps, and reports time series for each zone. 

Source code for MOD2BUD is provided in the data release for 

this report (Jackson and Halford, 2020).
100 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig51

Estimated predevelopment water level

EXPLANATION

Raw water level

Measured

Simulated

0

40

80

120 Depth to water, in feet below land surface

USGS 360836115531701 162 S21 E54 10AAC 1 ESB1

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Year

Figure 51. “Raw” water-level measurements, measured water levels, which are annual averages of measured waterlevel data during an annual stress period, and simulated water levels in well ESB1, Nevada, 1910–2020.

Reference water level

Estimated predevelopment water level

595

600

605

Depth to water level,

in feet below land surface

USGS 362230116392901 243 026N003E21L001S Travertine Point 1 (DV-3)

−10

−5

0

Water-level change, in feet

1950 1960 1970 1980 1990 2000 2010 2020

EXPLANATION

Simulated--calibrated DV3-AM-AFFCR

Alternative simulation

Raw water level

Measured, not compared

Measured, compared

Year

Figure 52. “Raw” water-level measurements, measured (average) water-level changes, and simulated 

water-level changes in terms of depth to water level (top graph) and water-level change (bottom graph), 

at well Travertine Point 1, California, 1950–2018. DV3-AM-AFFCR, Death Valley version 3 model simulating 

groundwater development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, and Pahute Mesa–Oasis 

Valley groundwater basins.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 101

sac19-4233_fig 53

SM-23-1

TW-5 (RV-1)

Spring Meadows 9

Spring

Meadows 12

North Crystal Well

Devils Hole

(AM-4)

Tracer Well 3 (AD-6)

Devils Hole

Well (AM-5)

Amargosa Desert 8

(AD-8)

Point of Rocks

South (AM-7)

Point of Rocks

North (AM-6)

ALKALI FLAT–FURNACE CREEK RANCH

PAHRUMP TO

DEATH VALLEY

SOUTH

ASH MEADOWS

Specter Range

116°20' 116°10' 116°

36°

40'

36°

30'

0 5 MILES

0 5 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security Site 

boundary—internal 

operations areas dashed

Transmissivity distribution, in 

feet-squared per day

Less than 10

10 to 100

100 to 1,000

1,000 to 10,000

10,000 to 100,000

100,000 to 1,000,000

1,000,000 to 29,000,000

Extent of megachannel, as 

delineated from:

Winograd and Pearson (1976)

This study using a transmissivity of 20,000 feet-squared 

per day

Map

area

Study 

area

Figure 53. Estimated transmissivity distribution from integrated Death Valley version 3 model, extent of megachannel, and 

wells with measured water levels noticeably affected by natural fluctuations from recharge, Nevada National Security Site 

and vicinity, Nevada.
102 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Well ER-6-1-2 main Multiple-Well Aquifer Test—

DV3-ER612 Model

Drawdowns from the well ER-6-1-2 main MWAT differed 

from water-level changes during groundwater development 

because drawdowns were attributed exclusively to pumping 

in well ER-6-1-2 main. This was possible because estimates 

of these drawdowns in observation wells were isolated from 

other water-level changes using water-level models (Halford 

and others, 2012). Water-level models removed effects of 

barometric and Earth tidal fluctuations, and effects of pumping 

from wells WW-C-1 and Army 1 WW from measured water 

levels (Jackson and Halford, 2019). Estimated drawdowns 

solely were from pumping of well ER-6-1-2 main. Drawdowns 

from the MWAT could be isolated because they were not 

correlated with water-level changes from all other stresses.

Long-term trends in observation wells were not 

accounted for, but minimally affected drawdown estimates 

from the well ER-6-1-2 main MWAT. Effects of long-term 

trends were minimal because less than 1 year of water-level 

record was analyzed for each well, except in Tracer Well 3. 

Long-term trends were not estimated with water-level models 

because background water levels were unavailable. Long-term 

rising trends in wells ER-7-1 and ER-3-1-2 (shallow) were 

both an increase of 0.07 ft/yr. These trends equate to rises of 

0.04 ft during the period of analysis, which are small relative 

to drawdowns greater than 0.3 ft in these wells (Jackson and 

Halford, 2019). The long-term trend in Tracer Well 3 was less 

than a 0.02-ft increase during 2004. Removing the long-term 

trend would increase the maximum drawdown in Tracer Well 

3 by less than 0.01 ft, which equals the root-mean-square 

(RMS) error in the drawdown estimates (Jackson and Halford, 

2019).

Regularization Observations

Tikhonov regularization informed parameters insensitive 

to measurement observations (Doherty, 2010a). Parameters 

were values of hydraulic conductivity (foot per day), specific 

yield (decimal percent), specific storage (1 per foot), and 

recharge rate (foot per day) at pilot points.

Tikhonov regularization observations were equations that 

defined either a preferred value at a pilot point or a preferred 

relation between pilot points. In the preferred-value approach, 

a single equation is provided for each adjustable parameter 

(pilot point) that equates the parameter to the preferred value. 

Preferred relations between pilot points were specified as 

ratios of preferred (or expected) values between pilot points, 

which guided relative differences rather than absolute values. 

For example, preferred hydraulic conductivities of 0.3 and 30 

ft/d at two pilot points would specify a preferred ratio of 100. 

Hydraulic-conductivity estimates of 5 and 500 ft/d at the two 

pilot points would perfectly agree with the preferred relation 

because the ratio is 100.

If the preferred relation is homogeneity, then pilot points 

within a zone are assigned the same initial preferred value 

and the preferred ratio between pilot points is 1. By invoking 

homogeneity, Tikhonov regularization limits differences 

between pilot points by penalizing sharp differences, and 

thereby ensuring relatively continuous distributions (Doherty 

and Johnston, 2003). Contrasts within hydrogeologic units and 

recharge zones were penalized minimally in areas where data 

informed the objective function.

The preferred relation between pilot points for the 

recharge distribution was ratios of the conceptual average 

annual recharge (fig. 16). Initial recharge estimates at pilot 

points were sampled from the conceptual recharge distribution 

(fig. 16). Recharge rates were estimated independently at 

all pilot points, but preferred ratios of conceptual recharge 

rates did not change between pilot points during calibration. 

A maximum of 30,000 regularization observations initially 

constrained recharge estimates with these preferred relations.

For each hydrogeologic unit, zones of conceptualized 

homogeneous transmissivity were the preferred relation 

between pilot points for hydraulic-conductivity distributions. 

Preferred hydraulic conductivity equaled preferred 

transmissivity of a zone divided by thickness of the 

hydrogeologic unit at a pilot point. For example, conceptual 

transmissivity of shallow carbonate rocks was distributed 

with homogeneous zones (fig. 43). Simulated hydraulic 

conductivities were interpolated smoothly between zones 

throughout each hydrogeologic unit because zones of 

homogeneity were speculative. Homogeneous transmissivity 

zones were incorporated as regularization observations instead 

of as parameters, so transmissivity in a hydrogeologic unit 

could differ where dictated by measurement observations. 

About 30,000 regularization observations constrained 

hydraulic-conductivity estimates with these preferred 

relations.

Homogeneity was the preferred relation between pilot 

points for specific yield and specific storage. Preferred values 

of specific yield for basin fill and consolidated rocks were 0.1 

and 0.02, respectively. Preferred values of specific storage 

were 2 × 10-6 1/ft. About 2,000 regularization observations 

constrained specific-yield and specific-storage values with 

these preferred relations.

Regularization observations were weighted so that 

preferred relations were emphasized where measurement 

observations were few. Regularization observations were 

weighted relative to separation distances between pilot points 

and the nearest measurement sites. Regularization-observation 

weights between pilot-point pairs were equal to 1 where 

the distance between the two pilot points was less than the 

separation between a measured water level and the nearest 

pilot point. Weights between pilot-point pairs decreased as the 

distance between the pilot points was more than the distance 

between a measured water level and the nearest of the two 

pilot points. Distances between measurement sites were less 

than 1 mi through Pahute Mesa, Rainier Mesa, Yucca Flat, 

Oasis Valley, Yucca Mountain, Frenchman Flat, the central 

Amargosa Desert, Ash Meadows discharge area, and Pahrump 

Valley, and exceeded 10 mi in northern Three Lakes Valley 

and the Black Mountains (fig. 46).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 103

Unrealistic hydraulic-property distributions were 

avoided partially by preventing overfitting of measurement 

observations (Fienen and others, 2009). Goodness-of-fit was 

limited so that the weighted, sum-of-squares error could not be 

reduced to less than irreducible measurement and numerical 

model errors. This expected measurement error is a weighted, 

sum-of-squares error and is the variable PHIMLIM in a PEST 

control file (Doherty, 2010a). A PHIMLIM of 8,000,000 ft2 

was specified, which is equivalent to an RMS error of about 50 

ft for water-level measurements and approximates the average 

allowable misfit between the simulated and measured water 

level at each well.

Goodness of Fit

Goodness of fit was evaluated with scatter plots, a 

map of residuals (simulated minus measured), water-level 

profiles, hydrographs, and hydraulic-property distributions. 

Steady-state calibration primarily was evaluated with scatter 

plots of simulated and measured water-level altitudes and 

transmissivities. A map of predevelopment (steady-state) 

water-level residuals identified systematic spatial biases. 

Agreement between vertical and lateral gradients was 

checked with profiles of measured and simulated water levels. 

Calibration of groundwater-development and MWAT models 

was evaluated by agreement between measured and simulated 

hydrographs of water-level changes in each well. Calibration 

of groundwater-development models also was evaluated by 

agreement between measured and simulated changes in spring 

discharges from pumping (table 9). Major hydrologic features 

have been identified in conceptual models from water-level 

profiles, hydrographs, transmissivity estimates, and a refined 

hydrogeologic framework. Simulation of these hydrologic 

features was evaluated qualitatively by comparing measured 

water-level profiles and hydrographs to simulated equivalents 

and examining simulated hydraulic-property distributions.

Predevelopment Observations

Simulated water levels compare favorably to measured 

water levels in the DV3-SS model (fig. 54). Average and 

RMS water-level errors of +1 and 49 ft, respectively, are not 

large relative to the 8,800-ft range of measured water levels 

(fig. 54). Measured water-level altitudes range from -281 to 

8,504 ft in Death Valley playa and the Spring Mountains, 

respectively. Differences between simulated and measured 

water levels from the DV3-SS model have been reduced 

by about a factor of 5, compared to the DVRFS.v2 model 

(fig. 54).

Water-level residuals show little spatial pattern of 

significance, suggesting a good overall fit between simulated 

and measured water levels (fig. 55). Water-level residuals 

average about 20 ft in transmissive areas such as Jackass 

Flats, the central Amargosa Desert, Ash Meadows discharge 

area, Furnace Creek area, and northern Pahrump Valley. 

Water-level residuals exceed 100 ft in high-altitude, highrelief, low-transmissivity areas such as Eleana Range, Groom 

Range, Sheep Range, and Spring Mountains. These residuals 

are interspersed positive and negative values that exhibit little 

spatial bias (fig. 55). Water-level residuals of more than 100 

ft are expected in high-relief areas because simulated water 

levels are very sensitive to small amounts of recharge across 

low-permeability rocks, land-surface altitudes span more than 

500 ft across these model cells, and the simulated water levels 

computed at cell centers are averages that are being compared 

to average land-surface altitudes across the model cell.

Spring-pool altitudes are underestimated and 

overestimated at perched springs in Groom Range, Sheep 

Range, and Spring Mountains, whereas nearby water-table 

altitude observations are overestimated (above land surface) 

(fig. 55). This occurred because land-surface altitudes span 

more than 500 ft across these model cells, water-table 

observations have disproportionate sensitivity, and recharge 

pilot points did not coincide with the locations of watertable observations. Water-table observations are inequalities, 

where water-table altitudes can be only overestimated 

because the altitudes were set equal to land surface for each 

optimization iteration if the water table was below land 

surface. This means that the water-table residual can be 0 ft 

after the first optimization iteration and 500 ft after the next 

iteration. The simulated water table is very sensitive to small 

changes in recharge in these areas of low-permeability rock, 

but parameter estimation only can “see” the parameters that 

overestimate the water table. Because recharge pilot points 

did not coincide with water-table observations, reductions 

or additions of recharge at pilot points lowered or raised the 

simulated water table near these spring pools while attempting 

to lower the water table at the water-table observations. Future 

modeling efforts should ensure that recharge pilot points and 

water-table observations occur at the same locations.

Simulated water levels in ET areas were within 50 ft of 

measured values at 86 percent of the sites. Spatial patterns 

generally were absent in simulated water levels in these ET 

areas, except in the Ash Meadows discharge area, Chicago 

Valley, and north and east of Tecopa (fig. 55). Simulated 

water levels in ET areas ranged from 50 to 60 ft greater than 

measured values in the Ash Meadows discharge area. Future 

modeling efforts should focus on better calibration to remove 

the spatial bias in the Ash Meadows discharge area. Simulated 

water levels are overestimated and underestimated in northern 

and southern Chicago Valley. Simulated water levels are 

underestimated east of Tecopa and overestimated north of 

Tecopa. Measured and simulated spring-pool altitudes differ 

by less than 30 ft around Tecopa (fig. 55). Spatial biases in 

Chicago Valley and near Tecopa are structural model errors 

that cannot be resolved with the limited data available.
104 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig54

−1,000

0

2,000

4,000

6,000

8,000

10,000

11,000

−1,000 0 11,000

Simulated altitude, in feet above National Geodetic Vertical Datum of 1929

Measured altitude, in feet above National Geodetic Vertical Datum of 1929

2,000 4,000 6,000 8,000 10,000

1:1

DVRFS.v2—All altitudes, root-mean-square (RMS) = 237 feet

Water table comparison to land surface, RMS = 59 feet

Water level in evapotranspiration area, RMS = 35 feet

Spring pool, RMS = 63 feet

Water level in well, RMS = 49 feet

EXPLANATION

Figure 54. Comparison of measured and simulated water-level altitudes from the calibrated Death Valley Regional Flow 

System version 2 model (DVRFS.v2) and Death Valley version 3 steady-state model (DV3-SS), in the study area, Nevada 

and California. Measured observations include estimated land-surface altitudes, estimated water-level altitudes in 

evapotranspiration areas, spring-pool altitudes, and measured water levels in wells. The four types of observations are 

combined from the DVRFS.v2 model and shown as one symbol.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 105

sac19-4233_fig 55

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

AD-4

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Chicago Valley

Emigrant 

Valley

Devils

Hole 

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

Observation well or site

Residual in steady-state 

observations—Simulated minus 

measured altitude, in feet. 

Residuals are grouped as either 

less than -50 feet (< -50), between 

-50 and +50 feet (-50 to +50), or 

greater than +50 feet (> +50).

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and 

internal operations areas

<-50 -50 to 50 >50

Water level in 

well

Spring pool

Water level in 

evapotranspiration area 

Water table 

comparison to 

land surface

Dumont

Dunes

Figure 55. Steady-state water-level altitude residuals in the Death Valley version 3 steady-state model (DV3-SS), in the 

study area, Nevada and California.
106 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Simulated and measured transmissivities generally agree, 

with 76 percent of sites within the 95-percent confidence 

interval (fig. 56). Simulated and measured transmissivities 

geometrically average 440 and 650 ft2/d, respectively. The 

log standard deviation of residuals from all observations of 

aquifer-test transmissivity, which excludes specific-capacity 

estimates, is 0.9 or a multiplier of 8. Simulated transmissivities 

range from 6 × 10-4 to 1 × 106

 ft2/d, or nine orders of 

magnitude. This is similar to measured transmissivities that 

range from 2 × 10-5 to 4 × 105 ft2/d, 10 orders of magnitude. 

Simulated transmissivities from the DV3-SS model agree with 

aquifer-test results an order of magnitude better than simulated 

transmissivities from the DVRFS.v2 model.

Simulated predevelopment discharge estimates totaled 

54,700 acre-ft, which agree with expected discharge estimates 

from 53,600 to 54,900 acre-ft/yr (table 4). Simulated and 

measured discharges agree in rate and location because 52,500 

acre-ft/yr or 97 percent, was specified. The remainder of 

discharges that were simulated with specified heads agreed 

with measured discharges or were within estimated ranges 

(table 11). South of Tecopa was the location of the greatest 

discharge simulated with a specified head in the DV3-SS 

model, where measured and simulated discharges were 1,100 

and 1,000 acre-ft/yr, respectively.

Groundwater-Development Observations 

Calibration of groundwater-development models 

primarily was evaluated with hydrographs and mapped extents 

of simulated drawdown. Differences between simulated 

and measured water-level changes in hydrographs were the 

quantitative measure of model fit. Measured and simulated 

hydrographs also were examined qualitatively for agreement 

between trends. Mapped extents of simulated drawdown 

(fig. 57) were compared to areas that were affected by 

groundwater development (figs. 29 and 32). Comparisons 

between previously estimated and simulated extents were 

necessarily qualitative but provided a useful guide for 

consistency between numerical and conceptual models of 

groundwater flow.

Measured and simulated water-level declines in the 

central Amargosa Desert pumping center closely match, with 

RMS errors of 3 ft (fig. 58). Measured water-level declines 

in well AD-5 were replicated closely except for the steeper 

measured declines after 2010. Departure between simulated 

and measured water-level changes could have resulted from 

erroneous pumping estimates or from effects of dewatering the 

basin fill that were not simulated. Unknown rates of pumping 

during 2011–18 were assumed equal to pumping estimates 

for 2010 (fig. 30). Transmissivity near well AD-5 likely is 

decreasing as basin fill is desaturated, but this process was not 

simulated. Potential desaturation seems a more likely reason 

for the poor fit at well AD-5, given consistent agreement 

between measured and simulated levels in TG Well and other 

wells where cumulative water-level declines were less than 30 

ft (fig. 58). Simulated and measured water-level declines agree 

within carbonate wells Inyo-BLM 1 (fig. 58C) and Travertine 

Point 1 (fig. 52), which are 7 and 15 mi, respectively, from 

maximum simulated drawdown in the central Amargosa 

Desert (fig. 57). Hydrograph fits improved with RMS errors 

of less than 1 ft as observation wells were more distant from 

pumping wells. This was because water levels were affected 

less by seasonal pumping and assignment of pumping well 

locations.

Measured and simulated hydrographs agree from wells 

at the perimeter of the area affected by the central Amargosa 

Desert pumping, with RMS errors of 0.05–0.5 ft (fig. 59). 

Simulated water-level declines in well AD-1 agree with 

the measured decline from 1990–2018. The simulated rate 

of water-level decline in well NC-EWDP-Washburn-1X 

(deep) is about 20 percent steeper than the measured decline 

from 2000–2015. A steeper simulated trend is conceptually 

acceptable because rising water-level trends exist in wells 

north of well NC-EWDP-Washburn-1X (deep). Naturally 

rising trends in these wells likely mask the northern extent of 

the area affected by pumping in the central Amargosa Desert 

(fig. 57). Slight declines were measured and simulated in 

wells DVJ-02 and WRPMW-4 along the southern and western 

extents, respectively, of the area affected by pumping in 

the central Amargosa Desert (fig. 59). Water-levels in well 

WRPMW-4 also were affected by local pumping in the Furnace 

Creek area that began during 2009 and a recharge event in 

2010 (fig. 59D). Both regional and local pumping effects are 

simulated correctly (fig. 59).

Measured and simulated water-level trends in Pahrump 

Valley match, with RMS errors of 5–10 ft in hydrographs near 

pumping wells. Misfits increased with proximity to assigned 

pumping wells, as observed in wells GSA, SD2, and JAW that 

were less than 1, 1.5, and 5 mi, respectively, from the nearest 

pumping well (fig. 60). Misfits were less than 1 ft in well JAW, 

which was farthest from pumping wells. Near the center of 

pumping, fits between measured and simulated water-level 

changes were sufficiently close relative to measured changes 

in excess of 80 ft, such as was observed in well ESB1 (fig. 51).

Better agreement exists between simulated and 

measured water levels in the central Amargosa Desert 

(fig. 58), compared to Pahrump Valley (fig. 60). Differences 

in model fit between pumping centers possibly were caused 

by differences in estimated pumping in the central Amargosa 

Desert and Pahrump Valley. About 30 percent of the volume 

pumped in Pahrump Valley occurred prior to the first pumpage 

inventory of Pahrump Valley in 1959 (Nevada Division of 

Water Resources, 2018). Multiyear periods of estimated 

uniform pumping indicate uncertainty of pumping estimates 

from Pahrump Valley prior to 1959 (fig. 30). Pumpage from 

the central Amargosa Desert was inventoried intermittently 

from 1965–1983 and verified with imagery after 1973 (Moreo 

and others, 2003). Pumpage was inventoried consistently in 

the study area after 1984, when pumping from the central 

Amargosa Desert increased generally and Pahrump Valley 

decreased (fig. 30).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 107

sac19-4233_fig56

1:1

95-percent confidence interval

1×107

1×106

1×105

1×104

1×103

1×102

1×101

1

1×10−1

1×10−2

1×10−3

1×10−4

1×10−5

Simulated transmissivity, in feet squared per day

Measured transmissivity, in feet squared per day

1×10−5 1×10−4 1×10−3 1×10−2 1×10−1 1 1×101 1×102 1×103 1×104 1×105 1×106 1×107

DVRFS.v2—Aquifer test

DV3-SS—Aquifer test

DV3-SS—Specific capacity

EXPLANATION

Figure 56. Comparison of simulated and measured transmissivities from the Death Valley Regional Flow 

System version 2 model (DVRFS.v2) and Death Valley version 3 steady-state model (DV3-SS), in the study area, 

Nevada and California.
108 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 57

117° W 116° W 115° W

37° N 36° N

Fortymile Wash

Amargosa River

Amargosa River

Chin a R anch

Wash

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Emigrant 

Valley

Tracer

Well 3

Devils Hole

Last Chance 

Well Travertine 

Point 1 DVJ-02

InyoBLM 1

AD-4

BLM 

Stewart 

Valley

Jeep

Trail

AD-5

AD-1

Hwy 127 

MM21-1 

JAW ESB1

022N007E13L01S 021N010E04L01S 

WRPMW-4

TG Well

NC-EWDPWashburn-1X 

(deep)

North Crystal Well

USAF Well 3

ER-3-1-2 (shallow)

ER-7-1

UE-1h ER-6-1-2 main

WW-4

WW-4A

GSA

SD2

EXPLANATION

Groundwater basin 

boundary modified from 

Fenelon and others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Extent of megachannel, as 

delineated in this study 

using a transmissivity of 

20,000 feet squared per day

Ash Meadows discharge 

area

Hydrograph well or site

Simulated water-level 

change, in feet

0 to 1

1 to 2

2 to 5

5 to 10

10 to 20

20 to 50

50 to 100

100 to 205

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 115°30'

37°

30'

36°

30'

Dumont

Dunes

Figure 57. Maximum simulated drawdown and selected observation sites with hydrographs shown in this report, in the 

study area, Nevada and California, 2018.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 109

sac19-4233_fig58

Year

0

10

20

30

B. USGS 363346116322801 230 S16 E48 14BAAA1 TG Well

Simulated predevelopment depth to water is 98 feet below land surface

0

10

20

30

40

50

A. USGS 363310116294001 230 S16 E49 18DCCA1 USBLM Well (AD-5)

Simulated predevelopment depth to water is 100 feet below land surface

0

10

20

C. USGS 362402116280901 230 026N005E07R001S Inyo-BLM 1

Simulated predevelopment depth to water is 79 feet below land surface

Water level change, in feet

1950 1960 1970 1980 1990 2000 2010 2020

EXPLANATION

Raw water level

Measured

Simulated

Figure 58. “Raw” water-level measurements and simulated and measured (average) water-level declines 

in wells AD-5 (A), TG Well (B), and Inyo-BLM 1 (C), in the central Amargosa Desert, Nevada and California, 

1950–2018.
110 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 59

Year

0

1

2

C. USGS 361818116271802 230 025N005E17J002S DVJ-02

Simulated predevelopment depth to water is 110 feet below land surface

0

1

2

3

4

B. USGS 363951116252402 227A S15 E49 11ACD 2 NC-EWDP-Washburn-1X (deep)

Simulated predevelopment depth to water is 356 feet below land surface

-1

0

1

2

A. USGS 364141116351401 230 S14 E47 32DA 1 NA-6 Well BGMW-10 (AD-1)

Simulated predevelopment depth to water is 269 feet below land surface

0

1

2

1950 1960 1970 1980 1990 2000 2010 2020

D. USGS 362646116480401 243 027N002E19Q001S WRPMW-4

Simulated predevelopment depth to water is 352 feet below land surface

Water-level change, in feet

EXPLANATION

Raw water level

Measured

Simulated

Figure 59. “Raw” water-level measurements and simulated and measured (average) 

water-level declines in wells AD-1 (A), NC-EWDP-Washburn-1X (deep) (B), DVJ-02 (C), 

and WRPMW-4 (D) that result from pumping in the central Amargosa Desert, Nevada and 

California, 1950–2018.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 111

sac19-4233_fig 60

Year

A. USGS 361554115595501 162 S19 E53 27DD 1 GSA

Simulated predevelopment depth to water is 30 feet below land surface

0

20

40

60

80

100

0

20

40

60

80

100

120

0

20

40

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Water-level change, in feet

B. USGS 361753116000901 162 S19 E53 15DB 1 SD2

Simulated predevelopment depth to water is 52 feet below land surface

C. USGS 361012116044701 162 S20 E52 36BD 1 JAW

Simulated predevelopment depth to water is 24 feet below land surface

EXPLANATION

Raw water level

Measured

Simulated

Figure 60. “Raw” water-level measurements and simulated and measured (average) water 

levels in wells GSA (A), SD2 (B), and JAW (C), in Pahrump Valley, Nevada, 1910–2020.
112 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Measured and simulated hydrographs agree from wells at 

the perimeter of the area affected by Pahrump Valley pumping, 

with RMS errors between 0.1 and 1 ft (fig. 61). Measured 

water levels consistently declined from 2005 to 2015, with 

total declines of 3.3 and 2.5 ft in wells BLM Stewart Valley 

Well and Last Chance Well, respectively. Measured waterlevel decline and recovery of 15 ft were matched within 1 ft in 

well Jeep Trail (fig. 61). Water levels were not measured from 

1976 to 2004 in well Jeep Trail, but the pattern of simulated 

water levels declining gradually and recovering rapidly after 

1997 is similar to the measured water-level trend in well ESB1

(fig. 51). Simulated and measured water-level declines from 

1959 to 1975 were both 13 ft in well 021N010E04L01S, which 

was the southernmost well in Pahurmp Valley with water-level 

data (fig. 57). Simulated and measured water-level declines 

from 2005 to 2015 were both 0.6 ft in well Hwy 127 MM21-1, 

west of the Amargosa River.

Measured and simulated discharges from Bennetts and 

Manse Springs compare favorably, but goodness of fit is more 

qualitative (fig. 62). A 2,400 acre-ft/yr (3.3 ft3/s) increase 

in discharge from Bennetts Spring between 1927 and 1937 

suggests an undocumented alteration occurred. The orifice 

of Bennetts Spring was cleaned and deepened in 1941 and 

discharge increased 1,400 acre-ft/yr (2 ft3/s) (Harrill, 1986). 

Simulating these alterations would require estimating multiple 

pool altitudes and drain conductances that the available dataset 

cannot reasonably inform. Simulated discharges from both 

Bennetts and Manse Springs were sensitive to poorly known 

pumping rates and locations (fig. 62). Pahrump Valley spring 

observations accordingly were weighted less than other 

observation groups and contributed less than 1 percent of the 

error in the objective function (table 10).

Measured and simulated water-level trends in wells near 

isolated pumping centers agree but measured water levels 

are noisier (fig. 63). RMS errors approach cumulative waterlevel declines. These water levels were measured less than 

1 mi from the pumping well or in the pumped well itself. 

For example, wells WW-4 and WW-4A are 1,200 ft apart and 

pumped alternately for water supply in CP basin (fig. 57). 

Measured water levels frequently are recovering from recent 

pumping, where pumping and recovery cause water levels 

to be 10s of feet lower than the long-term water-level trend 

(fig. 63). The long-term declining trend in well WW-4 is 

caused by the slow dewatering of basin fill in CP basin 

(fig. 63). Head losses in the well from periods of pumping and 

recovery were not simulated, but yearly changes have been 

matched. Similar noise exists near other isolated pumping 

centers, such as in well USAF Well 3 in Indian Springs 

(fig. 63).

Estimated specific-yield and specific-storage distributions 

are better informed when more information is available. 

Specific-yield estimates of basin fill in the central Amargosa 

Desert and Pahrump Valley ranged from 0.1 to 0.3 (fig. 64). 

Specific yields less than 0.05 generally were estimated where 

consolidated rocks occurred at the water table. Storage 

coefficients (specific storage times thickness of layers 2–6) 

generally ranged from 0.0001 to 0.01, where estimable 

(fig. 65). Storage coefficients exceeded 0.01 in Pahrump 

Valley, where specific-storage estimates were constrained by 

an upper limit of 1 × 10-5 1/ft and basin fill was thicker than 

1,000 ft.

Overestimated specific yields and storage coefficients 

in Pahrump Valley are compensating errors that likely 

resulted from not explicitly simulating subsidence. Thick clay 

sequences occur in the basin fill of Pahrump Valley. These 

clays have compacted inelastically in response to declining 

water levels, which resulted in land subsidence (Harrill, 1986, 

p. 11). Inelastic specific storages of 4 × 10-5 to 1 × 10-3 1/ft have 

been estimated for similar clays in Las Vegas Valley (Harrill, 

1976; Pavelko, 2004). Overestimating a storage coefficient 

by 0.1 would be similar to explicitly simulating a 500-ft thick 

clay with an inelastic specific storage of 2 × 10-4 1/ft.

Well ER-6-1-2 main Multiple-Well Aquifer Test 

Heterogeneous transmissivity and specific-yield 

distributions in shallow carbonate rocks beneath Yucca Flat 

were required to match drawdowns from the well ER-6-1-2 

main MWAT within the limits of measurement uncertainty. A 

maximum drawdown of 1.9 ft was estimated in well ER-7-1

(fig. 66), with little attenuation or delay, 6 mi north of well 

ER-6-1-2 main (fig. 47). Maximum drawdown was limited 

to less than 0.3 ft in well ER-3-1-2 (shallow) (fig. 66), 4 mi 

northeast of well ER-6-1-2 main (fig. 47). Pumping 75 million 

gallons from well ER-6-1-2 main did not affect water levels in 

well UE-1h (fig. 67), about 4 mi west of well ER-6-1-2 main

(fig. 47). Drawdowns in wells ER-7-1, ER-3-1-2 (shallow), 

and UE-1h are consistent with a north-south trending corridor 

of transmissive, shallow carbonate rocks that are bounded on 

the east and west by low-transmissivity rocks (fig. 68).

Lack of drawdown in shallow carbonate rocks in western 

Yucca Flat was replicated in the DV3-ER612 model. Measured 

and simulated drawdowns in well UE-1h indicate no response 

to pumping well ER-6-1-2 main, where the RMS error of 0.01 

ft can be attributed entirely to drawdown-estimation error 

(fig. 67). Lack of drawdown was created by the juxtaposition 

of high-transmissivity carbonate rocks near well ER-6-1-2 

main, with low-transmissivity volcanic-sedimentary rocks and 

underlying deep carbonate rocks at well UE-1h.

Measurable drawdowns in Tracer Well 3 (fig. 67), which 

are caused by pumping well ER-6-1-2 main (fig. 68), indicate 

that a hydraulic connection exists between Yucca Flat and 

Tracer Well 3. This hydraulic connection has been reproduced 

plausibly because simulated and measured drawdowns in 

Tracer Well 3 agree with an RMS error of 0.01 ft (fig. 67). A 

high-transmissivity corridor extending from Yucca Flat to the 

Ash Meadows discharge area was conceptualized to exist to 

better simulate drawdowns in Tracer Well 3, more than 33 mi 

from pumping well ER-6-1-2 main (fig. 68). This estimated 

high-transmissivity corridor is a consistent extension of the 

previously postulated megachannel (fig. 68; Winograd and 

Pearson, 1976).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 113

Year

0

10

20

A. USGS 361515116100901 162 S19 E52 31 1 BLM Stewart Valley Well

Simulated predevelopment depth to water is 27 feet below land surface

0

10

20

Water-level change, in feet

B. USGS 362111116070101 230 S18 E52 27CDC 1 Last Chance Well

Simulated predevelopment depth to water is 541 feet below land surface

C. USGS 360017115460401 162 S22 E55 26DBCA1 JEEP TRAIL

Simulated predevelopment depth to water is 144 feet below land surface

0

10

20

30

0

10

20

30

0

10

20

E. USGS 360020116103701 240 022N007E13L01S 

Simulated predevelopment depth to water is 17 feet below land surface

0

10

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

F. USGS 360337116175101 Hwy 127 MM21-1

Simulated predevelopment depth to water is 84 feet below land surface

D. USGS 355655115543101 162 021N010E04L01S

Simulated predevelopment depth to water is 157 feet below land surface

EXPLANATION

Raw water level

Measured

Simulated

Figure 61. “Raw” water-level measurements and simulated and measured (average) waterlevel changes in wells BLM Stewart Valley Well (A), Last Chance Well (B), Jeep Trail (C), 

021N010E04L01S (D), 022N007E13L01S (E), and Hwy 127 MM21-1 (F) that result from pumping in 

Pahrump Valley, in the study area, Nevada and California, 1910–2020.
114 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 62

Year

Predevelopment = 4,300 acre-feet per year

Discharge, in cubic feet per second

A. USGS 361222115585801 Bennetts Spring

0

1

2

3

4

Discharge, in thousands of gallons per minute

B. USGS 360919115541501 162 S21 E54 03BCDB1 Manse Spring

0

2

4

6

8

0

2

4

6

8

10

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

0

1

2

3

Predevelopment = 5,400 acre-feet per year

EXPLANATION

Simulated

Measured

Figure 62. Comparison of simulated and measured discharges from Bennetts (A) and Manse (B)

Springs, Pahrump Valley, Nevada, 1910–2018.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 115

sac19-4233_fig 63

Year

Water-level change, in feet

0

10

20

30

A. USGS 365418116012601 160 S12 E53 12 1 WW-4

Simulated predevelopment depth to water is 829 feet below land surface

B. USGS 363452115405101 161 S16 E56 08BAAC1 USAF Well 3

Simulated predevelopment depth to water is 67 feet below land surface

0

10

20

1950 1960 1970 1980 1990 2000 2010 2020

EXPLANATION

Raw water level

Measured

Simulated

Figure 63. “Raw” water-level measurements and simulated and measured (average) waterlevel changes in well WW-4 in CP basin (A), and USAF Well 3 in Indian Springs (B), Nevada, 

1950–2018.
116 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 64

Devils Hole 

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

Ash Meadows

Pahute Mesa–

Oasis Valley

Alkali Flat–

Furnace

Creek

Ranch

Bullfrog

Hills

Pahrump to 

Death Valley

South

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

EXPLANATION

Observation site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

0.0000001 to 0.001

0.001 to 0.01

0.01 to 0.1

0.1 to 0.3

Specific yield, in decimal 

percent

Pilot point 

Basin fill

Hard rock

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 115°30'

37°

30'

36°

30'

Dumont

Dunes

Ash Meadows 

discharge area

Figure 64. Estimated specific-yield distribution and pilot points from integrated Death Valley version 3 model, in the study 

area, Nevada and California.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 117

sac19-4233_fig 65

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Devils Hole 

EXPLANATION

Observation site

Groundwater basin 

boundary modified from 

Fenelon and others (2016)

Nevada National Security 

Site boundary and 

internal operations areas

0.00001 to 0.0001

0.0001 to 0.01

0.01 to 0.5

Storage coefficient, 

dimensionless

Pilot point 

Basin fill

Hard rock

117°

37°

36°

116° 115°

0 20 MILES

0 10

10

20 KILOMETERS

116°30' 115°30'

37°

30'

36°

30'

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

Dumont

Dunes

Figure 65. Estimated storage-coefficient distribution, which is specific storage times thickness of model layers 2–6, and 

pilot points from integrated Death Valley version 3 model, in the study area, Nevada and California.
118 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 66

Pumping

Distance to pumping well = 4.0 miles

Root-mean-square error = 0.01 feet

A. USGS 370116115561302 160 S10 E54 35 2 ER-3-1-2 (shallow)

−0.5

0

Distance to pumping well = 6.2 miles

Root-mean-square error = 0.04 feet

B. USGS 370424115594301 159 S10 E54 18 11 ER-7-1

−2.0

−1.5

−1.0

−0.5

0

Drawdown, in feet

2004 2005

EXPLANATION

Simulated

Measured

J F M MA J J A S O N D J F M MA J J A S O N D

Figure 66. Periods when well ER-6-1-2 main pumped; simulated drawdowns from Death 

Valley version 3 model simulating pumping during the ER-6-1-2 main multiple-well aquifer 

test (DV3-ER612); and measured drawdowns, which were estimated from water-level models 

(Jackson and Halford, 2019), in wells ER-3-1-2 (shallow) (A), and ER-7-1 (B), Nevada, 2004–05.

Pumping

A. USGS 370005116040301 159 S11 E53 09 1 UE-1h

Distance to pumping well = 4.3 miles

Root-mean-square error = 0.01 feet

−0.1

0

0.1

Drawdown, in feet

−0.1

0

0.1

B. USGS 363213116133800 230 S16 E51 27BAA 3 Tracer Well 3 (AD-6)

Distance to pumping well = 33.4 miles

Root-mean-square error = 0.01 feet

2004 2005

EXPLANATION

Simulated

Measured

J F M MA J J A S O N D J F M MA J J A S O N D

Figure 67. Periods when well ER-6-1-2 main pumped; simulated drawdowns from Death 

Valley version 3 model simulating pumping during the ER-6-1-2 main multiple-well aquifer 

test (DV3-ER612); and measured drawdowns, which were estimated from water-level models 

(Jackson and Halford, 2019), in wells UE-1h (A), and Tracer Well 3 (B), Nevada, 2004–05.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 119

sac19-4233_fig 68

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

95

95

93

15

373

190

127

318

375

582

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Ash Meadows 

discharge area

Army 1 WW Tracer Well 3

ER-3-1-2 (shallow)

UE-1h

UE-10j (2232-2297 ft)

WW-2 (3422 ft)

ER-7-1

UE-7nS

U-3cn 5

Devils Hole

ER-6-1-2 main

ER-4-1 m1

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Transmissivity, in feet 

squared per day

Less than 10

10 to 100

100 to 1,000

1,000 to 10,000

10,000 to 100,000

100,000 to 1,000,000

1,000,000 to 29,000,000

Extent of megachannel, as 

delineated from:

Winograd and Pearson 

(1976)

This study using a transmissivity of 20,000 feet 

squared per day

Observation well or site

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

Figure 68. Estimated transmissivity distribution from integrated Death Valley version 3 model (DV3), extent of 

megachannel, and observation sites during well ER-6-1-2 main multiple-well aquifer test, in the study area, California and 

Nevada.
120 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Ash Meadows And Devils Hole

Simulated and measured predevelopment discharges, 

spring-pool altitudes, water-level changes from pumping, and 

spring captures were compared in the Ash Meadows discharge 

area to evaluate goodness of fit. Predevelopment discharges 

totaled 10,000 gal/min (16,150 acre-ft/yr) from all springs 

in the Ash Meadows discharge area, which is more than 60 

percent of all predevelopment discharges from both AFFCR 

and Ash Meadows groundwater basins (table 4). Average and 

RMS spring-pool altitude errors of -8 and 32 ft, respectively, 

are acceptable errors, even though the errors are noticeable 

relative to a 160 ft head difference between Devils Hole and 

Crystal Pool (fig. 69). Distributions of simulated hydraulic 

conductivities in the Ash Meadows discharge area could 

be improved, but errors mostly affect simulated water-level 

changes and spring captures from local pumping.

Predevelopment spring-pool altitudes and discharges 

in the Ash Meadows discharge area were better simulated 

with the DV3-SS model than the DVRFS.v2 model (fig. 69). 

Measured and simulated discharges agreed perfectly for 

each spring in the Ash Meadows discharge area because 

discharges were specified in the DV3-SS model (fig. 69). 

However, measured and simulated discharges are dissimilar 

at each spring and in aggregate for the DVRFS.v2 model. 

Simulated discharges from the DVRFS.v2 model varied little 

between springs compared to measured spring discharges that 

ranged from 5 to 2,940 gal/min (0.01 and 6.55 ft3/s; table 9). 

Simulated discharge from Crystal Pool in the DVRFS.v2 

model differed most and was 15 percent of measured discharge 

(fig. 69). Simulated discharges from the DVRFS.v2 model 

summed to slightly more than one-half of measured discharge 

from all springs in the Ash Meadows discharge area. Average 

and RMS spring-pool altitude errors of -54 and 68 ft from 

DVRFS.v2 are substantial errors. Misfits were larger where 

measured spring-pool altitudes exceeded 2,280 ft (fig. 69).

Water-level changes in Devils Hole and other wells in 

the megachannel (fig. 53) were evaluated differently during 

calibration from water-level changes in the remaining 

wells in the DV3-AM-AFFCR model. A different type of 

evaluation was required because long-term, natural water-level 

fluctuations were substantial in the Devils Hole area relative 

to effects of groundwater development. Simulated waterlevel changes in Devils Hole and nearby wells were fit in the 

objective function to measured water-level changes minus 

long-term, natural water-level fluctuations from recharge. 

The difference between measured and long-term natural 

fluctuations from recharge is assumed to represent pumping 

effects. Effects of pumping were simulated with the DV3-AMAFFCR model and long-term, natural water-level fluctuations 

were simulated with an analytical water-level model for Devils 

Hole (fig. 40) and other nearby wells (fig. 53). Hydrographs 

are presented with the original water-level measurements and 

simulated water levels that are the summation of numerical 

(DV3-AM-AFFCR) and analytical models (fig 70).

Measured and simulated water-level changes in Devils 

Hole agree, with an RMS error of 0.2 ft (fig. 70). Overall, 

water-level trends and responses to pumping stresses agreed 

well throughout the nearly 70-year period of record. Misfits 

between measured and simulated water-level changes were 

greatest during initial recovery from cessation of pumping 

by Cappaert Enterprises after 1976 (fig. 38). This misfit most 

likely resulted from underestimating spring capture and 

overestimating specific yield in the Ash Meadows discharge 

area of the DV3-AM-AFFCR model (fig. 64). Errors in 

estimated long-term natural fluctuations from recharge also 

contributed to misfits between measured and simulated waterlevel changes in Devils Hole.

Measured water-level changes in wells Spring Meadows 

12, North Crystal Well, and Tracer Well 3 are similar to 

changes in Devils Hole and are matched by their respective 

simulated water-level changes in the DV3-AM-AFFCR model 

(figs. 53 and 70). A systematic decline of about 1 ft occurred 

in all wells between 1965 and 1995. Simulated water levels 

suggested that water levels in all wells responded to pumping 

by Cappaert Enterprises and declined prior to 1980. All wells 

were inferred to be affected strongly by the megachannel 

because water levels respond consistently to pumping and 

earthquake stresses. Simulated water-level changes in these 

wells agree with the conceptual model of the megachannel 

as an areally extensive, highly transmissive feature in the 

shallow-carbonate rocks (fig. 53).

Changes in measured and simulated spring discharges 

agree in the Ash Meadows discharge area of the DV3-AMAFFCR model. Measured and simulated spring discharges in 

Ash Meadows agreed with an average RMS error of 120 gal/

min (0.3 ft3/s). This error is similar to seasonal fluctuations 

in the absence of pumping (fig. 71) and is small relative to 

measured discharges that ranged from 5 to 2,900 gal/min (0.01 

and 6.6 ft3/s). Periods of complete capture in Jack Rabbit 

Spring were simulated correctly during the summer from 

1970 to 1977. Simulated recovery lagged behind measured 

recovery in Jack Rabbit Spring from 1978 to 1980 and likely 

resulted from locally overestimated specific yields. Capture 

was overestimated in Point of Rocks Spring but seasonal 

fluctuations were simulated correctly (fig. 71). Simulated 

changes in spring discharges in Big Spring replicated 

measured seasonal fluctuations and recovery within the 

uncertainty of measured discharges (fig. 71).
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 121

sac19-4233_fig 69

Fairbanks

Soda Rogers

Longstreet

Purgatory Well

Cold

Five Springs

North Scruggs

School

Crystal Pool

Davis Point of Rocks

Jack Rabbit

King Pool

Big

Devils Hole

Fairbanks and Soda Rogers, Longstreet,

and Purgatory

Point of Rocks

Jack Rabbit and King Pool

Davis Crystal Pool

Cold

Five Springs

Big

Scruggs and School

Crystal Pool

2,100

2,200

2,300

2,400

2,500

2,100 2,200 2,300 2,400 2,500

Simulated altitude, in feet above NGVD29

Measured altitude, in feet above NGVD29

Simulated discharge, in 

thousands of gallons per minute

0

1

2

3

4

0 2 4 6 8

Measured discharge, in cubic feet per second

0

2

4

6

8

Simulated discharge, in cubic feet per second

0 1 2 3 4

Measured discharge, in thousands of gallons per minute

0 5 10 15 20

Total discharge, in thousands of acre-feet per year

Measured

DV3

DVRFS.v2

DVRFS.v2, RMS = 68 feet

DV3-SS, RMS = 32 feet

DVRFS.v2, RMS = 838 gallons per minute

DV3-SS, RMS = 0 gallons per minute

EXPLANATION

EXPLANATION

Figure 69. Measured, and DV3-SS- and DVRFS.v2-simulated pool altitudes (top 

graph) and spring discharges (middle graph), and total measured and simulated 

spring discharges (bottom graph), in the Ash Meadows discharge area, Nevada. 

DV3-SS, Death Valley version 3 steady-state model; DVRFS.v2, Death Valley 

Regional Flow System version 2 model; NGVD29, National Geodetic Vertical 

Datum of 1929; RMS, Root-mean-square error.
122 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 70

Year

Analytical model of long-term natural fluctuations

A. USGS 363213116133800 230 S16 E51 27BAA 3 Tracer Well 3 (AD-6)

Simulated predevelopment depth to water is 40 feet below land surface

0

1

2

3

Water-level change, in feet

B. USGS 363030116104501 230 S17 E51 01AAAB1 North Crystal Well

Simulated predevelopment depth to water is 59 feet below land surface

0

1

2

3

C. USGS 362529116160501 230 S18 E51 06AAB 1 Spring Meadows 12

Simulated predevelopment depth to water is 73 feet below land surface

0

1

2

3

4

5

D. USGS 362532116172700 230 S17 E50 36DC 1 Devils Hole (AM-4)

Simulated predevelopment depth to water is 1.0 feet below reference

0

1

2

3

4

5

1950 1960 1970 1980 1990 2000 2010 2020

EXPLANATION

Raw water level

Measured

Simulated

Figure 70. “Raw” water-level measurements, measured (average) water-level changes, and 

simulated water-level changes (summation of pumping from DV3-AM-AFFCR model and long-term 

natural fluctuations—recharge, steady discharge, and earthquakes—from analytical water-level 

model) in the megachannel, including wells Tracer Well 3 (A), North Crystal Well (B), and Spring 

Meadows 12 (C), and Devils Hole (D), Nevada, 1950–2018. DV3-AM-AFFCR, Death Valley version 3 

model simulating groundwater development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, 

and Pahute Mesa–Oasis Valley groundwater basins.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 123

sac19-4233_fig 71

Year

−2,000

0

2,000

4,000

6,000

8,000

0

5

10

15

Discharge, in gallons per minute

0

200

400 (600 acre-feet per year)

0

1

Discharge, in cubic feet per second

0

200

400

600

800

0

1

(1,000 acre-feet per year)

0

200

400

600

800

1,000

1,200

1968 1970 1972 1974 1976 1978 1980 1982

(1,700 acre-feet per year)

0

1

2

Spring capture

Pumping

Injection

Spring capture

Measured

Simulated

Predevelopment discharge

EXPLANATION

A. Monthly pumping, injection, and simulated spring capture in 

Ash Meadows discharge area

C. USGS 362405116161300 230 S18 E51 07 1 Point of Rocks Spring

B. USGS 362324116163900 230 S18 E51 18 1 Jack Rabbit Spring

D. USGS 362230116162001 230 S18 E51 19ACB 1 Big Spring (AM-8)

Figure 71. Monthly pumping by Cappaert Enterprises; injection into Devils Hole 

Well (AM-5); total simulated capture in the Ash Meadows discharge area from DV3-

AM-AFFCR model (A); and hydrographs showing measured and simulated (DV3-

AM-AFFCR model) discharges from Jack Rabbit (B), Point of Rocks (C), and Big (D)

Springs, Nevada, 1968–82. DV3-AM-AFFCR, Death Valley version 3 model simulating 

groundwater development in the Ash Meadows, Alkali Flat–Furnace Creek Ranch, 

and Pahute Mesa–Oasis Valley groundwater basins.
124 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Groundwater flow in the Ash Meadows discharge 

area is better simulated with the DV3 model than the 

DVRFS.v2 model partly because the DV3 model was 

calibrated as an integrated stress-response model (fig. 48). 

Separately simulating predevelopment flow and changes 

from groundwater development constrained calibration and 

minimized compensating errors. For example, predevelopment 

discharge of 630 gal/min (1.4 ft3

/s) from Jack Rabbit Spring

was simulated correctly with the DV3-SS model, but the 

simulated spring pool was 22 ft lower than the measured 

altitude (fig. 69). Capture from Jack Rabbit Spring was 

simulated correctly with a 2 ft extinction depth in the DV3-

AM-AFFCR model (fig. 71). Simulating these conditions with 

a drain in a single model would create compensating errors. 

Predevelopment discharge would be 0 with an extinction depth 

of 2 ft or little capture would be simulated with an extinction 

depth greater than 22 ft. Extinction depths seem overestimated 

in the DVRFS.v2 model because simulated capture from all 

springs in the Ash Meadows discharge area never exceeded 

40 gal/min (0.09 ft3/s), whereas maximum measured capture 

totaled 3,800 gal/min (8.5 ft3/s).

Hydrologic Features

Major hydrologic features have been identified in the 

study area that the DV3 model must replicate (table 12). 

Simulated adequacy of these major hydrologic features was 

evaluated qualitatively because many aspects of these features 

remain conceptual. Conceptual models of these hydrologic 

features were developed from limited measurements from 

wells and springs, which limits the ability to quantify model 

misfit. Quantification was limited further where conceptual 

models depended on water quality and other measured 

quantities that were not simulated explicitly. For example, 

existence of a megachannel upgradient of the Ash Meadows 

discharge area was postulated primarily on anomalous 14C 

concentrations in discharge from Crystal Pool (Winograd and 

Pearson, 1976).

Agreement between numerical and conceptual models 

of major hydrologic features was evaluated with water-level 

profiles, transmissivity estimates, and hydrographs. Numerical 

model results were considered improved where measured 

and simulated gradients between wells along a profile agreed 

(fig. 72). Total simulated transmissivities along a profile 

explained water-level gradients, characterized groundwaterbasin boundaries, and identified extremely transmissive and 

impermeable hydrologic features.

Water Table Beneath Rainier Mesa

Nuclear tests in tunnels beneath Rainier Mesa occurred 

within 300 ft of the shallow (perched and semi-perched) water 

table (U.S. Department of Energy, 2018), which makes the 

shallow water table a major hydrologic feature. Perched and 

semi-perched water-table mounds cause elevated water levels 

in the study area. Maximum altitude of the shallow watertable mound is about 6,200 ft above NGVD29 (fig. 73, A–A′) 

and is within 0.5 miles of well ER-12-3 piezometer (shown as 

borehole ER-12-3 on fig. 72). Limited recharge to the shallow 

water table moves through volcanic rocks that primarily are 

zeolitized tuffs with hydraulic conductivities of 1 × 10-5 ft/d 

(0.004 ft/yr). This recharge ultimately will discharge in either 

the PMOV, AFFCR, or Ash Meadows groundwater basin (U.S. 

Department of Energy, 2018).

Measured and simulated water tables beneath Rainier 

Mesa generally agree (fig. 73, A–A′), which is a prerequisite 

for correctly associating recharge with the location of its 

ultimate discharge. Elevated water levels in the study area 

generally coincide with areas of low transmissivity, except 

beneath the perched water table where higher transmissivity 

occurs in deep carbonate rocks beneath the low-transmissivity 

volcanic rocks (fig. 73, A–A′). For example, the top of 

the perched water table near well ER-12-3 piezometer in 

zeolitized tuff is about 1,800 ft higher than water levels in 

well ER-12-3 main (shown as borehole ER-12-3 in fig. 72), 

open to underlying carbonate rocks. The perched water table 

is controlled by vertical movement through low-permeability 

volcanic tuff. Correctly simulating the perched water table 

beneath Rainier Mesa became an objective because this 

hydrologic feature had not been simulated adequately by the 

DVRFS.v2 model.

Boundary Between AFFCR and PMOV Groundwater Basins

The boundary between PMOV and AFFCR groundwater 

basins is a major hydrologic feature. The boundary between 

PMOV and AFFCR groundwater basins from Bare Mountain 

to Rainier Mesa (fig. 72) has been interpreted as a no-flow 

boundary along a groundwater-flow path (Fenelon and others, 

2016), which has implications for radionuclide transport. If 

this boundary is a no-flow boundary, then contamination from 

nuclear testing beneath Pahute Mesa in the northwestern part 

of the NNSS will not migrate into the AFFCR groundwater 

basin. The boundary between PMOV and AFFCR groundwater 

basins was less certain than other PMOV boundaries 

because this boundary was defined based on predevelopment 

water levels and discharges, rather than a topographic or 

groundwater divide (Fenelon and others, 2016). This boundary 

was not simulated explicitly as a no-flow boundary; instead, 

predevelopment water levels and discharges were matched 

to simulated equivalents to determine whether a no-flow 

boundary is substantiated based on groundwater-flow paths.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 125

Table 12. Summary of major hydrologic features simulated in the integrated Death Valley version 3 model (DV3), for the study area, 

Nevada and California.

[Abbreviations: AFFCR, Alkali Flat–Furnace Creek Ranch; PDVS, Pahrump to Death Valley South; PMOV, Pahute Mesa–Oasis Valley]

Significant hydrologic feature Reason for significance

Relevant 

water-level 

profiles

Perched water-table mound beneath 

Rainier Mesa

Nuclear tests in tunnels beneath Rainier Mesa occur within 300 feet of the shallow 

(perched) water-table mound.

A-A′

Boundary between PMOV and AFFCR 

groundwater basins

Contamination from nuclear testing beneath Pahute Mesa potentially can migrate 

into AFFCR groundwater basin if the boundary is not a no-flow boundary. A no-flow 

boundary was determined in DV3 model based on fitting predevelopment water 

levels and discharges to simulated equivalents.

B-B′ and C-C′

Megachannel in shallow carbonate 

rocks between northern Yucca Flat and 

Ash Meadows discharge area

Conceptual feature initially postulated immediately upgradient of Ash Meadows discharge area that explained hydrochemical variations between Ash Meadows springs. 

High hydraulic diffusivity of the shallow-carbonate megachannel causes drawdowns 

to propagate quickly and recover slowly.

D-D′ and E-E′

Gravity fault in Ash Meadows discharge areaGravity fault causes the juxtaposition of low-permeability basin fill (clay, silt, and 

fine-grained sand) in central Amargosa Desert with highly transmissive carbonate 

rocks in Ash Meadows discharge area. Gravity fault impedes groundwater flow and 

causes water to discharge from springs in Ash Meadows discharge area.

E-E′

Well AD-4 corridor Well AD-4 corridor hydraulically connects Ash Meadows and AFFCR groundwater 

basins. Most of the flow that enters the AFFCR basin occurs through this corridor. 

Transmissive basin fill and carbonate rocks along the Gravity fault north of Ash 

Meadows discharge area allow for upwelling water in the carbonate to move into 

basin fill in the Amargosa Desert.

F-F′ and G-G′

Furnace Creek Wash Furnace Creek Wash allows regional groundwater flow to be conveyed to the alluvial 

fan on the Death Valley floor, where groundwater discharges by evapotranspiration 

from phreatophytes.

H-H′

Water table beneath Black Mountains 

and Greenwater Range

Black Mountains and Greenwater Range are interpreted as barriers to groundwater 

flow based on most recent water-table interpretations from all available data. The 

barrier impedes groundwater movement from central Amargosa Desert to Death Valley through the Black Mountains and Greenwater Range. In the PDVS groundwater 

basin, the barrier impedes groundwater flow beneath the Amargosa 

River to Death Valley through the Black Mountains.

I-I′

Continuous aquifer of carbonate rocks 

and basin fill between Spring Mountains and Amargosa River

Transmissive basin fill and carbonate rocks form a continuous aquifer between the 

principal recharge area in the Spring Mountains and discharge areas along the Amargosa River in the PDVS groundwater basin. Formation of a continuous aquifer has 

implications for pumping effects in Pahrump Valley, where drawdowns can propagate 

downgradient toward the Amargosa River.

J-J′
126 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 72

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Buckboard 

Mesa

Devils Hole

A A'

B'

C'

D,F' 

C

B D'

E'

G'

H'

I'

H

G

F

E

I

J'

J

ER-12-3

AD-4A

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Transmissivity, in feet 

squared per day

Less than 10

10 to 100

100 to 1,000

1,000 to 10,000

10,000 to 100,000

100,000 to 1,000,000

1,000,000 to 29,000,000

Transect of water-level 

profile

Observation well or site

Extent of megachannel, as 

delineated from:

Winograd and Pearson 

(1976)

This study using a transmissivity of 20,000 feet 

squared per day

Dumont

Dunes

Specter Range

Figure 72. Estimated transmissivity distribution from integrated Death Valley version 3 model and traces of water-level 

profiles through major hydrologic features, in the study area, Nevada and California. See figures 73–79 for water-level 

profiles A–A’ through J–J’.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 127

sac19-4233_fig 73

WW-8

ER-19-1-3 (shallow)

ER-12-3 piezometer

ER-12-1 ER-12-2

piezometer

Land surface

WW-2

High

Moderate

Low

Elevated water levels 

(includes perched 

zones)

N-tunnel

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Altitude, in feet above NGVD29

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

0 5 10

Distance, in miles

Transmissivity,

in feet squared per day 

Measured

Simulated

DVRFS.v2

EXPLANATION

A

WEST

A'

EAST

Figure 73. Measured water-level profile and simulated water-level profiles from Death Valley 

Regional Flow System version 2 model (DVRFS.v2) and Death Valley version 3 steady-state model 

(DV3-SS) (top graph), and transmissivity profile from the DV3-SS model (bottom graph), through 

Rainier Mesa, Nevada. Trace of water-level profile A–A’ is shown in figure 72.

Interpreting the boundary between PMOV and AFFCR 

groundwater basins as a no-flow boundary differs from 

previous conceptualizations (Waddell, 1982; Laczniak and 

others, 1996). In previous conceptualizations, groundwater 

flowed southward from Pahute Mesa, across the current 

boundary between PMOV and AFFCR groundwater basins, 

and towards Yucca Mountain (Laczniak and others, 1996). 

The conceptualization was developed with fewer wells 

and inaccurate predevelopment-discharge estimates from 

Oasis Valley and Franklin Lake of 2,000 and 10,000 acre-ft/

yr, respectively (Walker and Eakin, 1963; Waddell, 1982; 

Czarnecki and Waddell, 1984). Current discharge estimates 

from Oasis Valley and Franklin Lake total about 6,200 and no 

more than 700 acre-ft/yr, respectively (table 4).

The DV3-SS model implicitly simulated a no-flow 

boundary between the PMOV and AFFCR groundwater 

basins from Bare Mountain to Rainier Mesa (fig. 72). The 

measured water-level profile perpendicular to the boundary 

in Buckboard Mesa shows a notable difference in lateral 

gradients from well ER-18-2 (fig. 74, B–B′), indicating 

groundwater movement to the north and south of the 

boundary. Measured and simulated water levels have similar 

altitudes perpendicular to the boundary south of Timber 

Mountain (fig. 74, C–C′), indicating a lack of potential for 

flow across the boundary. Simulated flow perpendicular 

to the PMOV and AFFCR boundary is restricted by low 

transmissivity (fig. 74, B–B′) or small lateral gradients (fig. 74, 

C–C′) relative to gradients parallel to the boundary.

Megachannel

The megachannel (fig. 72) is a major hydrologic feature 

of the Ash Meadows groundwater basin because drawdowns 

within this feature propagate quickly and recover slowly. 

The megachannel initially was presented as a conceptual 

feature that explained hydrochemical variations between large 

springs in the Ash Meadows discharge area (fig. 72; Winograd 

and Pearson, 1976). The megachannel was delineated in 

this report as a contiguous extent of shallow carbonate 

rocks where transmissivity exceeds 20,000 ft2

/d (fig. 72). 

The boundary of the megachannel was generalized around 

areas of low transmissivity in the Ash Meadows discharge 

area and extended into northern Yucca Flat (fig. 72). The 

northern extent includes well UE-10j (2232-2297 ft) because 

drawdowns from pumping well ER-4-1 m1 were detected 

5.7 mi north in well UE-10j (2232-2297 ft) (fig. 68; Jackson, 

2017). The megachannel as delineated in this report primarily 

differs from Winograd and Pearson (1976) by extending 

into Yucca Flat (fig. 72). This extension is well defined by 

measurable drawdowns in Tracer Well 3 from pumping well 

ER-6-1-2 main (figs. 67–68).
128 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 74

ER-EC-1

ER-EC-11 shallow

UE-18r

ER-18-2

ER-30-1-2 shallow

High

Moderate

Low

ER-EC-4

ER-EC-8

ER-EC-5 ER-EC-7

UE-29a1

Pahute Mesa–

Oasis Valley

Alkali Flat–

Furnace Creek Ranch

High

Moderate

Low

Beatty Wash 

Windmill Well

4,100

4,200

4,300

Altitude, in feet 

above NGVD29

Transmissivity, in feet 

squared per day 

3,850

3,950

4,050

4,150

Altitude, in feet above NGVD29

Transmissivity, in feet 

squared per day 

0 5 10 15 20 25

Distance, in miles

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Measured

Simulated

Boundary between 

PMOV and AFFCR 

groundwater basins

EXPLANATION

B

NORTHWEST

B'

SOUTHEAST

C

NORTHWEST

C'

SOUTHEAST

Figure 74. Measured and simulated water-level profiles (top graph and third graph 

from top), and transmissivity profiles from the Death Valley version 3 steady-state model 

(DV3-SS) (second and fourth graphs from top), through boundary between Pahute Mesa–

Oasis Valley (PMOV) and Alkali Flat–Furnace Creek Ranch (AFFCR) groundwater basins, 

Nevada. NGVD29, National Geodetic Vertical Datum of 1929. Traces of water-level profiles 

B–B’ and C–C’ are shown in figure 72.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 129

The megachannel is characterized by carbonate rock 

with high transmissivities and low storativities (specific 

yield plus storage coefficient). In unconfined areas of the 

shallow-carbonate megachannel, specific yields were 

spatially variable and averaged 0.04. In confined areas of the 

megachannel, confined storage coefficients averaged 0.0001. 

High transmissivities and low storativities resulted in broad 

areas with hydraulic diffusivities greater than 1,000,000 ft2/d. 

Hydraulic diffusivities increased where overlying saturated 

basin fill locally reduced hydraulic connection between 

carbonate rocks and the water table.

High hydraulic diffusivities caused relatively uniform 

declines of 2 ft in the megachannel between 1970 and 1980 

from pumping by Cappaert Enterprises (fig. 70). About 

20,000 acre-ft of water drained from 250,000 acres in the 

megachannel between 1970 and 1980, which about equals net 

pumpage from Cappaert Enterprises minus spring capture in 

the Ash Meadows discharge area (fig. 38). Water levels in the 

megachannel recovered slowly during the ensuing decades 

after 1980 because surrounding rocks had low hydraulic 

diffusivities and did not readily release additional water 

(fig. 70).

Measured and simulated water-level profiles through the 

megachannel agree closely (fig. 75). Measured and simulated 

gradients between wells WW-2 (3422 ft) and Tracer Well 3

both averaged 1.0 ft/mi between northern Yucca Flat and 

Amargosa Flat (fig. 75, D–D′). Simulated gradients between 

well Army 1 WW and Devils Hole averaged 0.9 ft/mi, but were 

not as flat as measured gradients of 0.3 ft/mi (fig. 75, E–E′). 

Corresponding simulated transmissivities of the megachannel 

ranged from 10,000 to 10,000,000 ft2/d. Maximum simulated 

transmissivities locally exceed aquifer-test results in the 

megachannel by twentyfold, which would seem troubling if 

transmissivities between wells were not considered. Simulated 

transmissivity results were questioned and compared to 

Darcy estimates of transmissivity between well Army 1 WW

and Devils Hole. Darcy estimates of transmissivity ranged 

from 1,000,000 to 2,000,000 ft2/d, which is consistent with 

simulated transmissivities. Steep gradients between Devils 

Hole and Crystal Pool were simulated correctly with both 

simulated and measured gradients averaging 5 ft/mi (fig. 75, 

E–E′

). Steepening gradients were simulated with a three-orderof-magnitude decrease in transmissivities.

Gravity Fault

Water levels and simulated transmissivities from Crystal 

Pool to Franklin Well are consistent with basin fill west of the 

Gravity fault in the Ash Meadows discharge area impeding 

groundwater flow (fig. 75, E–E′). Basin fill in this area consists 

of clay, silt, and fine-grained sand of lacustrine origin (Walker 

and Eakin, 1963). Clay content exceeds 80 percent through 

more than 1,000 ft of basin fill (Oatfield and Czarnecki, 1989), 

with extensive deposits of bentonite and zeolite being mined 

north and south of section E–E′ (Castor and others, 2006). 

Simulated water levels, discharges, and transmissivities are 

consistent with previous interpretations of the Gravity fault 

being a groundwater barrier that “...is caused by normal 

faulting of the poorly permeable Cenozoic rocks against the 

lower carbonate aquifer,” (Winograd and Thordarson, 1975; 

p. C82).

Well AD-4 Corridor

The well AD-4 corridor is a major hydrologic feature 

that hydraulically connects Ash Meadows and AFFCR 

groundwater basins (fig. 72; fig. 76, F–F′, G–G′). Most 

groundwater that flows from the Ash Meadows groundwater 

basin to the AFFCR groundwater basin flows through a 

5-mi-wide corridor around well AD-4, where water upwells 

from underlying carbonate rocks to overlying basin fill. The 

area of upwelling water extends west to east about 2 mi 

between wells HA-AD68 and AD-4 (fig. 76, F–F′) and south 

to north about 5 mi between wells HA-AD67 and NC-GWEFELDERHOFF 25-01PA (fig. 76, G–G′). Water levels in the 

well AD-4 corridor are elevated 50–90 ft higher than water 

levels in wells immediately south, west, and north of the area 

of upwelling (fig. 76), which precludes all other sources of 

water other than flow from the underlying carbonate rocks.

Measured and simulated water levels through the well 

AD-4 corridor agree in profiles west to east and south to 

north (fig. 76). Simulated transmissivities are consistent 

with a corridor of limited lateral extent. Continuously 

transmissive rocks were simulated from west to east (fig. 76, 

F–F′) and from south to north (fig. 76, G–G′) through the 

5-mi-wide corridor beneath well AD-4. These transmissivity 

profiles are qualitative and do not represent all hydraulic 

components because vertical flow is not depicted explicitly 

and flow through the well AD-4 corridor is limited by lower 

transmissivities of basin fill farther west of the F–F′ profile. 

Simulated transmissivities west of well AD-4 ranged from 300 

to 3,000 ft2

/d, which are consistent with measured specific 

capacities of 3–5 ([gal/min]/ft).

Furnace Creek Wash

Furnace Creek Wash is a major hydrologic feature that 

allows regional groundwater flow to discharge from the 

alluvial fan on the Death Valley floor (fig. 9; fig. 72, H–H′). 

Measured and simulated water-level profiles closely agree 

(fig. 77), which was required to match the predevelopment 

water budget in the Furnace Creek area. The DV3-SS model 

simulated 5.8 ft3/s (4,170 acre-ft/yr) of groundwater entering 

Furnace Creek Wash, which is within a few percent of the 

predevelopment estimate of 5.6 ft3

/s (4,100 acre-ft/yr) being 

conveyed into Furnace Creek Wash (fig. 77). Simulated, 

predevelopment-groundwater flow leaves Furnace Creek 

Wash either from diversions or as subsurface flow. Furnace 

Creek Wash buried tile and sump, and the Furnace Creek Inn 

Tunnel (fig. 77) diverted 2.0 ft3/s (1,500 acre-ft/yr). Subsurface 

flow of 3.8 ft3/s (2,700 acre-ft/yr) exits Furnace Creek Wash 

near Furnace Creek Inn Tunnel, flows downgradient, and 

discharges by ETGW from the alluvial fan (fig. 77).
130 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 75

Tracer Well 3

Megachannel UE-10j (2232-2297 ft)

High

Moderate

Low

High

Moderate

Low

Megachannel

Franklin

Well

Evapotranspiration area in Carson Slough

Carson Meadows Well

Crystal Pool

School Spring Well

School

Spring

Well

Devils Hole

Devils Hole

Well (AM-5) Spring

Meadows

12

Amargosa

Flat Mine

Well S17 E52 08C 1

Hwy95 Cons 2

Army 1 WW

Gravity fault

USAF R65N

SM-23-1

WW-C-1 TW-E U-7a

ER-7-1 ER-6-1-2 main WW-2 (3422 ft)

2,300

2,400

2,500

Altitude, in feet 

above NGVD29

Transmissivity, in feet 

squared per day 

2,200

2,300

2,400

2,500

Altitude, in feet above NGVD29

2,100

Transmissivity, in 

feet squared per day 

0 10 20 30 40 50 60

Distance, in miles

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Measured

Simulated

EXPLANATION

E

SOUTHWEST

E'

NORTHEAST

D

SOUTHWEST

D'

NORTHEAST

Figure 75. Measured and simulated water-level profiles (top graph and third graph from 

top), and transmissivity profiles from the Death Valley version 3 steady-state model (DV3-SS)

(second and fourth graphs from top), through megachannel from Yucca Flat to the Ash 

Meadows discharge area, Nevada and California. NGVD29, National Geodetic Vertical 

Datum of 1929. Traces of water-level profiles D–D’ and E–E’ are shown in figure 72.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 131

sac19-4233_fig 76

026S048E35H01S

S16 E48 25AAAD1

HR Well

KD Well

HA-AD68

Tracer Well 3

High

Moderate

Low

20BCAC2

S17 E49 11BCAA1

S16E4926DD1

HA-AD67

High

Moderate

Low

Well AD-4 

corridor

AD-4

AD-9a

Well AD-4 corridor

AD-4

HA-AD70

NC-GWE-08PA

NC-EWDP 5SB

NC-GWE-FELDERHOFF

 25-01PA

2,200

2,300

2,400

Altitude, in feet above NGVD29

Transmissivity, in feet 

squared per day

2,200

2,300

2,400

Altitude, in feet above NGVD29

Transmissivity, in 

feet squared per day

0 5 10 15 20

Distance, in miles

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Measured

Simulated

EXPLANATION

F

WEST

F'

EAST

G

SOUTH

G'

NORTH

Figure 76. Measured and simulated water-level profiles (top graph and third graph from 

top), and transmissivity profiles from the Death Valley version 3 steady-state model (DV3-SS)

(second and fourth graphs from top), through the well AD-4 corridor, Nevada and California. 

NGVD29, National Geodetic Vertical Datum of 1929. Traces of water-level profiles F–F’ and

G–G’ are shown in figure 72.
132 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 77

Furnace Creek Wash Inn tunnel

Furnace Creek Wash sump

Furnace Creek Wash buried tile

UFCW-02

WRPMW-4

Furnace Creek Wash

Evapotranspiration area on alluvial fan

SMN-01TSHigh

Moderate

Low

TS-SMS-01

WRPMW-3

−400

0

400

800

Altitude, in feet above NGVD29

Transmissivity,

in feet squared per day 

0 2 4 6

Distance, in miles

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Measured

Simulated

EXPLANATION

H

WEST

H'

EAST

Figure 77. Measured and simulated water-level profiles (top 

graph), and transmissivity profile from the Death Valley version 3 

steady-state model (DV3-SS) (bottom graph), through the Furnace 

Creek area, California. NGVD29, National Geodetic Vertical Datum 

of 1929. Trace of water-level profile H–H’ is shown in figure 72.

Water Table Beneath Black Mountains and Greenwater Range

The Black Mountains and Greenwater Range are major 

hydrologic features that have been interpreted inconsistently. 

The water table beneath the Black Mountains and Greenwater 

Range was interpreted initially as a smoothly sloping surface 

from the Amargosa River on the east to the floor of Death 

Valley on the west (fig. 72) and originated from “...a handcontoured ground-water elevation map interpreted by the 

Denver Office of the USGS and transferred to PNL on March 

31, 1982” (Rice, 1984, p. 22). The sloping water table was 

simulated with the DVSS2 model (table 1; D’Agnese and 

others, 2002, p. 88).

The water table alternatively has been interpreted as a 

perched mound beneath the Black Mountains and Greenwater 

Range (D’Agnese and others, 1998, plate 1). Additional 

wells were inventoried in the Greenwater Range since 1982 

and influenced the reinterpretation (Kilroy, 1991, plate 1). 

The mounded water table was the conceptual model for 

flow beneath the Black Mountains and Greenwater Range in 

DVRFS.v1 (Faunt, D’Agnese, and O’Brien, 2010, p. 139), but 

was simulated as a sloping water table. A mounded water table 

of limited north-south extent was simulated with the DVRFS.

v2 model (Belcher and others, 2017, p. 44), but the conceptual 

model was a sloping water table (Belcher and others, 2017, 

plate 1). In the DVRFS.v2 model, the limited north-south 

extent of the perched water-table mound did not preclude flow 

through the Black Mountains and Greenwater Range because 

about 5,000 acre-ft/yr of discharge was simulated from the 

Death Valley floor south of the Furnace Creek area. Simulated 

groundwater flow in the DVRFS.v2 model moved around the 

limited extent of the perched water-table mound. However, 

more recent data indicate that the Black Mountains and 

Greenwater Range more likely behave as hydraulic barriers.

The Black Mountains and Greenwater Range are 

interpreted in this study as barriers to groundwater flow 

based on the most recent water-table interpretations from all 

available data. The barrier impedes groundwater movement 

from the central Amargosa Desert to Death Valley through 

the Black Mountains and Greenwater Range. In the PDVS 

groundwater basin, the barrier also impedes movement of 

groundwater flow beneath the Amargosa River to Death Valley 

through the Black Mountains (fig. 72). The Black Mountains 

and Greenwater Range consist of bedded tuffs and clastic, 

crystalline, and intrusive rocks (Sweetkind and others, 2001, 

plate 3), which are typically impermeable rocks.
Simulated Predevelopment Groundwater Flow 133

Steep hydraulic gradients and potential for limited local 

recharge indicate that the Black Mountains and Greenwater 

Range are low-transmissivity features. For example, water 

levels increase 2,475 ft between well 020N004E09K001S

and Virgin Spring in the Black Mountains (fig. 78, I–I′), 

which are a mapped distance of 8 mi apart (fig. 72), resulting 

in a hydraulic gradient greater than 300 ft/mi. Black 

Mountains and Greenwater Range are conceptualized as lowtransmissivity features, which limits the amount of recharge. 

Local recharge rates do not exceed 0.001 ft/yr (fig. 16) and can 

generate no more than 9 acre-ft/yr/mi (0.2 ft3/d/ft) between 

well KJ-2 and 021N004E15R002S. This limits average 

transmissivity to less than 10 ft2/d in the Black Mountains 

and Greenwater Range and is consistent with simulated 

transmissivities (fig. 78, I–I′).

Continuous Aquifer of Carbonate Rocks and Basin Fill in PDVS 

Groundwater Basin

Carbonate rocks and basin fill form a continuous aquifer 

between recharge in the Spring Mountains and discharge 

along the Amargosa River (fig. 72; fig. 79, J–J′). This 

conceptualization differs little from previous interpretations 

(Harrill, 1986, p. 27). Transmissive intervals primarily are 

hosted by carbonate rocks in the mountain blocks and basin 

fill in the valleys. Bennetts and Manse Springs occur at the 

contact between the alluvial fan and valley floor primarily 

because of a break in slope, not a reduction in transmissivity 

(fig. 79, J–J′). Transmissivity generally decreases from east 

to west between the Nopah Range and Amargosa River 

regardless of host rocks (fig. 72; fig. 79, J–J′). Measured and 

simulated water-level profiles from the Spring Mountains to 

the Amargosa River generally agree (fig. 79, J–J′).

Simulated Predevelopment 

Groundwater Flow

Predevelopment groundwater flow was characterized with 

the calibrated DV3-SS model. Recharge-source areas were 

mapped for each major discharge area with particle tracking. 

Groundwater flow was simulated from the Ash Meadows 

groundwater basin to the Furnace Creek area through the well 

AD-4 corridor. The Furnace Creek flow conceptualization 

is presented, which integrates results from previous 

investigations and compares the DV3 conceptualization to 

alternative conceptualizations. Simulated predevelopment 

water budgets were extracted for subareas in each groundwater 

basin. The simulated water budget also was extracted for the 

Rainier Mesa groundwater sub-basin because radionuclides 

from underground nuclear tests can migrate farther into the 

AFFCR, Ash Meadows, and (or) PMOV groundwater basins.

Recharge and Discharge Areas 

Recharge and discharge areas were paired for 

predevelopment flow with particle tracking (Pollock, 2012). 

Particles were backward-tracked from Bennetts, Manse, and 

Stump Springs in Pahrump Valley and from discharge areas in 

Oasis Valley, Ash Meadows, Lower Amargosa, and Furnace 

Creek to contributing recharge areas. Particles were seeded 

on the faces of cells where simulated discharge occurred. 

Each particle represented 50 acre-ft/yr, where the number 

of particles apportioned to each cell face was based on the 

total simulated discharge from each cell. Discharge from all 

analyzed areas totaled 47,000 acre-ft/yr and was backwardtracked with 940 particles. Connections between the initial 

particle location in the discharge area and the terminus at 

the water table in a recharge area are shown with pathlines 

(fig. 80). Areas with greater pathline densities represented 

areas with higher groundwater-flow rates. Pathlines were 

generated using an assigned effective porosity of 10 percent 

for basin fill and volcanic-sedimentary rocks, and an assigned 

effective porosity of 1 percent for fractured carbonate, 

volcanic, and low-permeability rocks.

Recharge also was mapped and differentiated between 

five major discharge areas by forward-tracking from the water 

table to discharge areas. The five major discharge areas were 

Oasis Valley, Ash Meadows, Furnace Creek, Lower Amargosa, 

and Pahrump and Stewart Valleys. The contributing recharge 

area for Pahrump and Stewart Valleys included all discharge 

from springs and ET areas. Particles were seeded at the 

water table in model cell centers where simulated recharge 

rates exceeded 0.0001 ft/d (fig. 45). Each cell at the water 

table was mapped to one of the five discharge areas (fig. 80). 

Recharge areas were not mapped if they contributed to minor 

discharge areas, such as Death Valley, Franklin Lake, and 

Saratoga Spring area. Mapped recharge areas supply 86 

percent of discharge from the study area. Groundwater-flow 

paths calculated by backward-tracking from discharge areas 

(pathlines) and forward-tracking from recharge areas (shading) 

are shown in figure 80.

Pahute Mesa is the primary recharge area contributing 

to discharge from Oasis Valley (fig. 80). Other highland areas 

that contribute recharge in the PMOV groundwater basin 

include Black Mountain, Timber Mountain, Cactus Range, 

and Kawich Range. Simulated contributing recharge areas for 

Oasis Valley generally agree with the previously delineated 

PMOV groundwater basin (Fenelon and others, 2016). Minor 

differences exist beneath Bare Mountain, east of the Belted 

Range, and north of Rainier Mesa (fig. 80).
134 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 78

Greenwater Range

Virgin Spring

Land surface

High

Moderate

Low

020N004E09K001S

021N004E15R002S

026N005E34N02S

AD-13

KJ-2

DVJ-01 NA-8

NA-7

Inyo-BLM 1a

−500

0

1,000

2,000

3,000

4,000

5,000

Altitude, in feet above NGVD29

Transmissivity,

 in feet squared per day 

0 10 20 30 40 50

Distance, in miles

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Black Mountains

Measured

Simulated

EXPLANATION

I

SOUTH

I'

NORTH

Figure 78. Measured and simulated water-level profiles (top graph), and transmissivity 

profile from the Death Valley version 3 steady-state model (DV3-SS) (bottom graph), 

through the Black Mountains and Greenwater Range, California. NGVD29, National 

Geodetic Vertical Datum of 1929. Trace of water-level profile I–I’ is shown in figure 72.
Integrated Estimation of Recharge and Hydraulic-Property Distributions with Numerical Models 135

sac19-4233_fig 79

Unnamed seep above Amargosa River

Tecopa Hills Spring

Tecopa Hot Springs

Chappo Spring

CHV1

022N007E13L01S Twelvemile

Spring

024N008E21L001S JAW

H & G

Bennetts Spring

Horse Springs

Land surface

High

Moderate

Low

Nopah Spring Mountains

Range

Resting 

Spring 

Range

Amargosa 

River

Chicago 

Valley

Pahrump 

Valley

PR-04

Altitude, in feet above NGVD29

0

1,000

2,000

3,000

4,000

5,000

6,000

Distance, in miles

0 10 20 30 40

Transmissivity, in feet 

squared per day 

1×10−1

1×100

1×101

1×102

1×103

1×104

1×105

1×106

1×107

Measured

Simulated

EXPLANATION

J

SOUTHWEST

J'

NORTHEAST

Figure 79. Measured and simulated water-level profiles (top graph), and transmissivity 

profile from the Death Valley version 3 steady-state model (DV3-SS) (bottom graph), from 

the Spring Mountains to the Amargosa River, Nevada and California. NGVD29, National 

Geodetic Vertical Datum of 1929. Trace of water-level profile J–J’ is shown in figure 72.
136 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 80

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Black 

Mountain

Shoshone 

Mountain

Saratoga 

Spring

area

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

Devils 

Hole

AD-4

Stewart Valley

Bennetts

Spring

Manse Spring

Stump Spring

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. 

Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

EXPLANATION

Groundwater-flow path, representing 50 acre-feet per year 

—from recharge areas to the 

following discharge areas

Recharge area—Colors at each 

location are the contributing 

recharge area for each discharge 

area. Colors are shown for model 

cells with simulated recharge 

greater than 0.0001 feet per day.

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Spring

Furnace Creek

Ash Meadows

Oasis Valley

Lower Amargosa

Pahrump and Stewart 

Valleys, including all spring 

and evapotranspiration 

areas

Furnace Creek

Ash Meadows

Oasis Valley

Lower Amargosa

Bennetts, Manse, and Stump 

Springs

Ash Meadows discharge 

area

Figure 80. Groundwater-flow paths to selected discharge areas and contributing recharge areas for discharge areas in 

Oasis Valley, Ash Meadows, Furnace Creek, Lower Amargosa, and Pahrump and Stewart Valleys, Nevada and California.
Simulated Predevelopment Groundwater Flow 137

The Ash Meadows discharge area predominantly is 

recharged from the Spring Mountains and Sheep Range in 

the southern and eastern Ash Meadows groundwater basin 

(fig. 80). Less than 5 percent of the discharge is recharged 

from the Desert, Pintwater, Spotted, Pahranagat, and Groom 

Ranges. Between the Pahranagat and Groom Ranges 

(fig. 80), groundwater in shallow carbonate rocks contributes 

to discharge in the AFFCR groundwater basin, whereas 

groundwater in deep carbonate rocks contributes to discharge 

in Ash Meadows groundwater basin. Flow from basin fill 

in southeast Frenchman Flat into shallow carbonate rocks 

ultimately will discharge in the Ash Meadows discharge area. 

Simulated flow through shallow carbonate rocks is consistent 

with hydrochemical interpretations of calcium-magnesiumsodium-bicarbonate type waters that discharge from springs in 

the Ash Meadows discharge area (Winograd and Thordarson, 

1975).

Bennetts and Manse Springs were primary discharges 

in Pahrump Valley prior to development and were recharged 

from the central Spring Mountains in the northern PDVS 

groundwater basin (fig. 80). Stump Spring is a relatively minor 

discharge of less than 300 acre-ft/yr that is recharged in the 

southwestern Spring Mountains (fig. 80). All recharge for 

springs in Pahrump Valley flowed through carbonate rocks 

prior to discharging from Bennetts, Manse, or Stump Springs.

Discharge in the Lower Amargosa area primarily is 

recharged in the Spring Mountains (fig. 80). Contributing 

recharge areas to the Lower Amargosa area extend north and 

south of the recharge areas for Bennetts and Manse Springs 

in the central Spring Mountains. About 10 percent of the 

discharge from the Lower Amargosa area is recharged in 

the Nopah, Resting Spring, and Greenwater Ranges. More 

flow was simulated through the northern Nopah Range into 

Chicago Valley than through the southern Nopah Range near 

California Valley (fig. 80).

Pathlines from recharge in the Spring Mountains to 

discharge along the Amargosa River show that carbonate 

rocks and basin fill form a continuous aquifer in the PDVS 

groundwater basin. Water recharges the carbonate rocks in 

the Spring Mountains, moves through basin fill and shallow 

carbonate rock beneath Pahrump Valley, and leaves Pahrump 

Valley through carbonate rocks in the Nopah Range (fig. 81). 

Groundwater flows through the northern part of the Nopah 

Range, Chicago Valley, and the southern part of the Resting 

Spring Range, and discharges near the Amargosa River. 

Groundwater flow functionally ceases west of the Amargosa 

River because of the exclusive occurrence of low-permeability 

rocks (fig. 32). Increasing occurrence of low-permeability 

rocks from east to west affects groundwater flow more than 

whether carbonate rocks or basin fill occur along the flow 

path.

Flow from Ash Meadows Groundwater Basin to 

the Furnace Creek Area

Discharge in the Furnace Creek area is atypical in 

the study area because a substantial part of the discharge 

is recharged in another groundwater basin (fig. 80). The 

Furnace Creek area is in Death Valley on the western edge of 

the AFFCR groundwater basin. More than 40 percent of the 

discharge in the Furnace Creek area is sourced from the Ash 

Meadows groundwater basin, with the remaining Furnace 

Creek discharge derived from the AFFCR groundwater basin 

(Fenelon and others, 2016).

Hydraulic connection between Ash Meadows 

groundwater basin and the Furnace Creek area has been 

explained with two alternative flow-path conceptualizations 

(fig. 82). The path through basin fill in the central Amargosa 

Desert is an alternative that has been presented piecemeal 

in previous investigations. This flow-path conceptualization 

assumes that most of the discharge sourced from the Ash 

Meadows groundwater basin passes through the well AD-4

corridor to reach the Furnace Creek area (figs. 80 and 82). 

The alternative path is flow through deep carbonate rocks 

that extend between the Ash Meadows discharge area and 

the southeastern Funeral Mountains, where flow moves 

northwest along the Furnace Creek fault zone to discharge 

areas in Furnace Creek (fig. 82; Hunt and Robinson, 1960; 

Belcher and others, 2009). These two alternatives will be 

discussed hereinafter as basin-fill and deep-carbonate flow 

paths. Lithology, hydraulic properties, chemical evidence, and 

numerical simulation results indicate that the basin-fill flow 

path is more likely than the deep-carbonate flow path.

Basin-Fill Flow Conceptualization

The basin-fill flow conceptualization assumes that basin 

fill in the central Amargosa Desert hydraulically connects the 

Furnace Creek area with carbonate rocks in Ash Meadows 

groundwater basin (fig. 83). Groundwater recharged in the Ash 

Meadows groundwater basin flows west-southwest through 

shallow carbonate rocks and converges on the well AD-4

corridor (fig. 80). Groundwater flows upward from carbonate 

rocks to basin fill in the well AD-4 corridor, moves west 

through the central Amargosa Desert, flows from basin fill 

to carbonate rocks in the Funeral Mountains, and continues 

to flow westward (fig. 83). Some of the westward-flowing 

groundwater discharges directly from carbonate rocks at 

Nevares Springs and the rest passes through shallow basin fill 

in the Furnace Creek area before discharging at land surface.
138 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 81

Amargosa 

River

Resting 

Spring 

Range Chicago 

Valley

Nopah 

Range

Pahrump Valley

Spring Mountains

Top of DV3 model layer 6

Altitude above National Geodetic Vertical Datum

of 1929, in feet

FEET

A

SOUTHWEST

FEET

A'

NORTHEAST

6,000

4,000

2,000

0

-2,000

8,000

6,000

8,000

4,000

2,000

0

-2,000

Distance along flow path from discharge area, in miles

0 5 10 15 20 25 30 35 40 45 50

EXPLANATION

Death Valley version 3 model

 (DV3) hydrogeologic unit

Basin fill

Shallow carbonate rocks

Deep carbonate rocks

Volcanic-sedimentary rocks

Granitic and siliciclastic rocks

Land-surface profile

Simulated groundwater-flow path–

 arrow shows direction of flow

Simulated water table from 

 Death Valley version 3 steady-state

 model (DV3-SS)

A

A'

Ash 

Meadows 

discharge area

Figure 81. Cross section along a simulated groundwater-flow path from the Spring Mountains to the 

Amargosa River, Nevada and California.
Simulated Predevelopment Groundwater Flow 139

sac19-4233_fig 82

95

95

373

190

Amargosa River

Fortymile Wash

Mercury

Beatty

Furnace 

Creek

CALIFORNIA

NEVADA

NYE

INYO

Oasis Valley

Timber 

Mountain

Yucca Mountain

Funeral Mountains

Black Mountains

Death Valley

Spring Mountains

Yucca Flat

Frenchman Flat

Specter Range

Eleana Range

Bare Mountain

Jackass Flats

Central Amargosa 

Desert

ALKALI FLAT–

FURNACE CREEK

RANCH

PAHUTE MESA–

OASIS VALLEY

BULLFROG ASH MEADOWS HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

U-3cn 5

WW-C-1

TW-F

Army 1 WW

Texas 

Springs

Travertine 

Springs

Nevares 

Springs

J-12 WW

J-13 WW

Burrell Hot 

Spring

Big Spring

Devils Hole

Crystal

Pool

Fairbanks 

Spring

AD-4

Inyo-BLM 1

Felderhoff 

Federal 5-1

Travertine 

Point 1

Basin-fill flow path

Furnace Creek fault zone

Deep-carbonate flow path

0 10 MILES

0 5

5

10 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°

37°

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Observation well or site

Conceptual groundwater flow 

path

Ash Meadows discharge 

area

Fault

Where flow is in carbonate

Where flow is in basin fill

Map

area

Study 

area

Figure 82. Basin-fill and deep-carbonate flow-path conceptualizations from the Ash Meadows groundwater basin to 

discharge areas in Furnace Creek, Nevada and California.
140 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 83

Funeral Mountains 

Furnace 

Creek area

Amargosa Desert Specter Range

Well AD-4 corridor –

area of groundwater upwelling

Top of DV3 model layer 6

Top of DV3 model layer 6

Alkali Flat–Furnace Creek Ranch groundwater basin Ash Meadows groundwater basin

Altitude above National Geodetic Vertical Datum

of 1929, in feet

FEET

A

SOUTHWEST

FEET

A'

NORTHEAST

6,000

4,000

2,000

0

-2,000

8,000

6,000

8,000

4,000

2,000

0

-2,000

Distance along flow path from discharge area, in miles

0 5 10 15 20 25 30 35 40 45 50

EXPLANATION

Death Valley version 3 model

 (DV3) hydrogeologic unit

Basin fill

Shallow carbonate rocks

Deep carbonate rocks

Volcanic-sedimentary rocks

Granitic and siliciclastic rocks

Land-surface profile

Simulated groundwater-flow path–

 arrow shows direction of flow

Simulated water table from 

 Death Valley version 3 steady-state

 model (DV3-SS)

Ash 

Meadows 

discharge area

A A'

Figure 83. Cross section along a simulated groundwater-flow path from the Ash Meadows groundwater 

basin to the Furnace Creek area through the well AD-4 corridor, Nevada and California.

Flow Potential Through Well AD-4 Corridor

Potential for flow from Ash Meadows groundwater basin 

into basin fill in the well AD-4 corridor has been recognized 

for 55 years, but estimated flow rates have differed greatly. 

Predevelopment water-level contours show a potentiometric 

high around the well AD-4 corridor that radially decreases 

into the central Amargosa Desert (Walker and Eakin, 1963, 

plate 3). A potentiometric high can occur from mounding 

from recharge, which is unlikely on a desert valley floor, or 

from groundwater upwelling. Upwelling of groundwater from 

carbonate rocks into overlying basin fill along the Gravity 

fault is supported by water-chemistry data. Water chemistry in 

wells open to basin fill within 0.4 mi of well AD-4 and springs 

in the Ash Meadows discharge area was classed as chemically 

similar (“Ash Meadows” and “East-central Amargosa Desert” 

in Winograd and Thordarson, 1975, p. C100). Winograd and 

Thordarson (1975, p. C87) dismissed substantial flow from 

carbonate rocks to basin fill near well AD-4 (figs. 82 and 83) 

because low-permeability siliciclastic rocks were assumed 

prevalent east of well AD-4. Claassen (1985 p. F19) analyzed 

drillers’ logs and additional wells, and concluded that, 

“...[hydraulic] potential difference and the presence of more 

permeable sand and gravel in the valley fill in the vicinity of 

site 27 [well AD-4] support the presence of significant upward 

leakage from the carbonate aquifer.” About 2,000 acre-ft/yr of 

flow through the corridor was estimated from transmissivity 

and hydraulic-gradient estimates in the basin fill west of well 

AD-4 (Fenelon and others, 2016).

Drilling history of wildcat oil and gas well Felderhoff 

Federal 5-1 qualitatively supports the ability of shallow 

carbonate rock to transmit substantial flow through the well 

AD-4 corridor. Felderhoff Federal 5-1 was drilled 1.6 mi 

northeast of well AD-4 (fig. 82), encountered carbonate rocks 

850 ft below land surface, and reached a total depth of 1,466 

ft below land surface (Carr and others, 1995). The well was 

abandoned before reaching its target depth of 5,000 ft below 

land surface because circulation using the mud-rotary drilling 

method could not be maintained. During October 22–25, 

1991, less than 100 ft of hole was drilled near the bottom of 

the borehole (1,466 ft) while about 100,000 gal (2,500 barrels) 

of mud and cement were injected. Fluid-level altitudes of 

2,354 ft were unchanged during injection and are consistent 

with expected water levels in shallow carbonate rocks at 

this location. Lack of circulation despite injection of large 

fluid volumes and unchanged water levels suggest hydraulic 

connection of the borehole with highly transmissive features 

in the carbonate rock. Geophysical measurements in the 

carbonate-rock sidewall of the borehole had bulk densities of 

1.1 g/cm3

, which is low compared to average bulk densities 

that typically exceed 2.6 g/cm3

 for carbonate rocks. Low 
Simulated Predevelopment Groundwater Flow 141

measured bulk densities and a fully expanded caliper log 

between 1,410 and 1,445 ft below land surface are highly 

suggestive of large voids in the carbonate rocks (Carr and 

others, 1995).

Flow Potential Through Basin Fill in the Central Amargosa 

Desert

Transmissivities of basin fill in the central Amargosa 

Desert are sufficient to convey greater than 6,000 acre-ft/yr 

of groundwater to carbonate rocks in the Funeral Mountains. 

This groundwater is sourced from carbonate rocks east of 

the well AD-4 corridor, volcanic rocks at and upgradient of 

Yucca Mountain and Jackass Flats, and local recharge from 

the Amargosa River and Fortymile Wash (fig. 80). Specific 

capacities equal or exceed 20 gal/min/ft in 11 wells in the 

basin fill that overlie dense pathlines through the central 

Amargosa Desert (fig. 80). Pumping rates exceed 2,000 gal/

min in five wells that were reported in Nevada well logs 4379, 

4821, 7633, 9510, and 27276 (Nevada Division of Water 

Resources, 2018). Simulated transmissivities of basin fill in 

the central Amargosa Desert ranging from 10,000 to 100,000 

ft2/d are consistent with empirical evidence from well logs 

(fig. 76, F–F′).

Basin-Fill, Carbonate-Rock, and Volcanic-Rock Hydraulic 

Connections

The basin-fill flow conceptualization assumes basin 

fill, carbonate rocks, and volcanic rocks are hydraulically 

connected between recharge areas and the Furnace Creek 

discharge area. Recharge derived from Yucca Mountain and 

nearby upland areas in the AFFCR groundwater basin enters 

primarily volcanic rocks, moves downgradient into basin fill 

in the central Amargosa Desert, and passes through carbonate 

rocks in the Funeral Mountains (fig. 80). Recharge derived 

from Ash Meadows groundwater basin moves downgradient 

through carbonate rocks, enters basin fill in the central 

Amargosa Desert through the well AD-4 corridor, and moves 

into carbonate rocks in the Funeral Mountains (fig. 83). 

Recharge derived from the Amargosa River and Fortymile 

Wash infiltrates basin fill beneath the ephemeral channels and 

then moves into carbonate rocks in the Funeral Mountains. 

Water entering the Funeral Mountains from these different 

source areas moves westward to discharge in the Furnace 

Creek area (fig. 80).

Water-level data support west-southwest movement 

of groundwater through basin fill, carbonate rocks, and (or) 

volcanic rocks toward Furnace Creek. Predevelopment waterlevel contour maps show west-southwest groundwater flow 

toward the Furnace Creek area (Walker and Eakin, 1963, 

plate 3; Fenelon and others, 2010, plates 3–6; Fenelon and 

others, 2016, plate 1). Fenelon and others (2010, plates 3–4) 

show groundwater-flow potential between alluvial-volcanic 

and carbonate-rock aquifers based on lateral and vertical head 

gradients between wells.

Water-level declines with time in wells Inyo-BLM 1

and Travertine Point 1 confirm that basin fill in the central 

Amargosa Desert and carbonate rocks of the Funeral 

Mountains are connected hydraulically. The hydraulic 

connection was first reported in Fenelon and Moreo (2002, 

fig. 26). Both wells are completed in carbonate rocks, but 

on opposites sides of the Funeral Mountains (fig. 82). Well 

Travertine Point 1 is more than 10 mi west of well Inyo-BLM 

1, which is adjacent to basin fill in the central Amargosa 

Desert. Water levels declined 4 ft per decade in well InyoBLM 1 (fig. 58C) and 3 ft per decade in well Travertine Point 

1 (fig. 52). In basin fill on the western side of the Amargosa 

Desert, water levels in NA-9 Shallow Well declined 5 ft/decade 

(Jackson and Halford, 2020). Consistent declines through the 

Funeral Mountains that diminish with distance from pumping 

in the Amargosa Desert (fig. 57) indicate a strong hydraulic 

connection with the central Amargosa Desert. Similar 

arguments confirm that basin fill in the central Amargosa 

Desert and volcanic rocks in Jackass Flats are hydraulically 

connected (fig. 57).

Geochemically Differentiated Sources of Furnace Creek 

Area Discharge

Major-ion and stable-isotope water chemistry can be 

used to identify potential source areas that contribute to 

Furnace Creek area discharge. Major-ion chemistry evolves 

from source areas to the discharge area, where dissolved-solid 

content typically increases along groundwater-flow paths 

(Drever, 1988). Stable isotopes of deuterium and oxygen-18 

can be used to evaluate sources of Furnace Creek discharge. 

Deuterium and oxygen-18 concentrations are lighter (more 

negative) where recharge occurs at higher altitudes or cooler 

temperatures. Deuterium and oxygen-18 concentrations are 

affected minimally by water-rock interactions and evolve 

along flow paths by simple mixing (Thomas and others, 1997; 

p. C31).

Major Ions

The spatially variable, major-ion chemical character 

of groundwater across the study area results mostly from 

reaction with and dissolution of different rock types along 

flow paths. Groundwater in the Ash Meadows groundwater 

basin is characterized as a calcium-magnesium-sodiumbicarbonate type water (figs. 84 and 85). Well sites in Ash 

Meadows groundwater basin are open to carbonate rock 

and Ash Meadows springs are sourced from carbonate rock 

(fig. 84). The groundwater chemistry can be explained by long 

flow paths through carbonate rock that mix with groundwater 

derived from volcanic rocks. Calcium-magnesium-bicarbonate 

type groundwater is characteristic of carbonate rocks, 

whereas sodium-potassium-bicarbonate type groundwater is 

characteristic of volcanic rocks in the study area (Winograd 

and Thordarson, 1975). The addition of sodium likely is 

derived from downward leakage of groundwater through 

overlying volcanic rocks into carbonate rocks (Winograd and 

Thordarson, 1975, C104).
142 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 84

95

373

190

Amargosa River

Fortymile Wash

Mercury

Beatty

Furnace 

Creek

CALIFORNIA

NEVADA

NYE

INYO

Oasis Valley

Timber 

Mountain

Yucca Mountain

Funeral Mountains

Black Mountains

Death Valley

Spring Mountains

Yucca Flat

Frenchman Flat

Specter Range

Eleana Range

Bare Mountain

Jackass Flats

Alkali Flat–

Furnace Creek

Ranch

Pahute Mesa–

Oasis Valley

Bullfrog Ash Meadows

Hills

Central 

Amargosa 

Desert

Western Amargosa Desert

U-3cn 5

WW-C-1

TW-F

Army 1 WW

Grapevine 

Spring

Death Valley 

Junction Well

Navel

Spring

Texas

Springs

Travertine

Springs

Nevares

Springs

J-12 WW

J-13 WW

UE-29a 2 HTH

USW G-2

USW H-1 HTH

USW H-4 HTH

USW H-5 HTH

USW VH-1

UE-25b 1 HTH

MR-3

Burrell Hot 

Spring

II-2

II-1

Big Spring

Jack Rabbit Spring

Amargosa Tr Hole 2

Point of Rocks Spring

King Pool Spring

Devils Hole

Crystal

Pool

Five Springs Area

Longstreet Spring

Rogers Spring

Soda Spring

Fairbanks Spring

USW H-6 HTH

58

54

53

52

49

48

46

41

40

39

36

35

30

29

27

26

24

19 18

17

16

14

13 11

9

7

5

4

3

62

61

InyoBLM 1

UE-25c 2 HTH

USW G-4

34

28

42

38

15 31

33

32 10

12

8

6

23

37

25

45

50

47

20

21

0 10 MILES

0 5

5

10 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°

37°

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Ash Meadows discharge 

area

Ash Meadows discharge 

area

Carbonate site in Ash 

Meadows basin

Central Amargosa Desert

Furnace Creek area

Yucca Mountain–Jackass 

Flats area

Well AD-4 corridor

Western Amargosa Desert

TW-F

MR-3

20

Stiff diagram of major-ion water chemistry 

—values in milliequivalents per liter

Sodium and potassium

Calcium

Magnesium

Chloride and fluoride

Bicarbonate and carbonate

Sulfate

Cations Anions

015 -15

Site and site identifier with 

major-ion chemistry data

Site and site identifier with 

major-ion and stableisotope data

Site and site identifier with 

stable-isotope data

Groundwater-flow direction

Map

area

Study 

area

Figure 84. Water-chemistry sites in the Alkali Flat–Furnace Creek Ranch and Ash Meadows groundwater basins, 

Nevada and California. Water-chemistry data are compiled from Claassen (1973, 1985), Dudley and Larson (1976), and 

Thomas and others (1997), and are reported in Jackson and Halford (2020).
Simulated Predevelopment Groundwater Flow 143

sac19-4233_fig 85

Calcium (Ca2+) Chloride (Cl−) + Fluoride (F−)

Magnesium (Mg2+)

Sulfate (SO4

2−)

Sodium (Na+

) + Potassium (K+

)

Bicarbonate (HCO3

−

) + Carbonate (CO3

−

)

Chloride (Cl−

) + Fluoride (F−

) + Sulfate (SO4

2−)

Calcium (Ca2+) + Magnesium (Mg2+)

100

80

60

40

20

0

0

20

40

60

80

100 0

100

100

100

100

80

60

40

20

0

0

100

80

60

40

20

0

20

40

60

80

80

60

40

20

20

0

40

60

80

80

60

40

20

80

60

40

20

0

0

0

20

40

60

80

100

100

100

Ash Meadows discharge area

Carbonate site in Ash Meadows basin

Central Amargosa Desert

Furnace Creek area

Well AD-4 corridor

Western Amargosa Desert

Yucca Mountain–Jackass Flats area

EXPLANATION

PERCENT

PERCENT

PERCENT

Figure 85. Major ion water chemistry for sites in the Alkali Flat–Furnace Creek Ranch and Ash 

Meadows groundwater basins, Nevada and California. Water-chemistry data are compiled from 

Claassen (1973, 1985), Dudley and Larson (1976), and Thomas and others (1997), and are reported in 

Jackson and Halford (2020).

Groundwater in the well AD-4 corridor is chemically 

similar to Ash Meadows springs (Winograd and Thordarson, 

1975, p. C100). Wells 27 (also known as 230 S16 E50 07 1) 

and 28 (also known as HA-AD70) in the well AD-4 corridor 

(fig. 84) are a calcium-magnesium-sodium-bicarbonate type 

(fig. 85), but have greater dissolved-solid concentrations (660 

mg/L) compared to Ash Meadows springs (520–580 mg/L). 

Increased dissolved-solid concentrations are attributed to the 

addition of sodium and sulfate from mixing with groundwater 

in basin fill, where the likely source of sulfate is evaporite 

deposits, such as gypsum, within the basin fill (Winograd and 

Thordarson, 1975).

Major-ion chemistry varies spatially in the AFFCR 

groundwater basin because groundwater is derived from 

different sources (fig. 84). The chemical character of 

groundwater from volcanic rocks in Yucca Mountain and 

Jackass Flats and groundwater near Fortymile Wash (fig. 84) is 

a dilute sodium-potassium-bicarbonate type (fig. 85; Winograd 

and Thordarson, 1975) with dissolved-solid concentrations 

ranging from 200 to 315 mg/L. This chemical character is 

similar to groundwater from wells farther south in the central 

Amargosa Desert, such as Well 4 (also known as 

230 S16 E49 05ACC 1) and Well 11 (also known as HR Well) 

in figure 84. Recharge derived from flood events along the 

Amargosa River infiltrates basin fill south of Bullfrog Hills 

and in western Amargosa Desert (fig. 84). Near the river 

channel, groundwater in underlying basin fill, carbonate rocks, 

and volcanic rocks is a sodium-chloride-sulfate-bicarbonate 

type (fig. 85) with dissolved-solid concentrations ranging 

between 700 and 950 mg/L.
144 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

A considerable fraction of discharge from the Furnace 

Creek area has long been attributed to recharge in Ash 

Meadows groundwater basin based on the water chemistry 

of Furnace Creek spring discharges (Hunt and Robinson, 

1960; Hunt and others, 1966; Winograd and Thordarson, 

1975; Steinkampf and Werrell, 2001; Belcher and others, 

2009). Discharge from the Furnace Creek area also has been 

proposed to derive exclusively from basin fill in the Amargosa 

Desert. Winograd and Thordarson (1975, p. C112) concluded: 

“Therefore, on the basis of chemical quality of water, the 

spring discharge at the Furnace Creek Wash-Nevares springs 

area seems to come from water in the valley-fill aquifer of 

the central and northwestern Amargosa Desert rather than 

directly from Pahrump Valley or from Pahrump Valley via 

Ash Meadows.” The chemical character of discharge in the 

Furnace Creek area is a sodium-sulfate-bicarbonate type with 

dissolved-solid concentrations ranging from 760 to 820 mg/L 

(fig. 85), which is distinct from the water chemistry of Ash 

Meadows springs (fig. 84). This discharge is a mixture of 

calcium-magnesium-sodium-bicarbonate type groundwater 

with additional sulfate and chloride (Winograd and 

Thordarson, 1975, p. C99).

Examination of the available major-ion data plausibly 

suggests that Furnace Creek area discharge is a chemical 

evolution, or mixture, of groundwater derived from both the 

Ash Meadows and AFFCR groundwater basins (fig. 84). The 

component coming from the Ash Meadows groundwater 

basin is calcium-magnesium-sodium-bicarbonate type water 

moving from shallow carbonate rocks west of well Army 1 

WW into the AFFCR groundwater basin through the well AD-4

corridor (fig. 84). The components coming from the AFFCR 

groundwater basin are dilute sodium-potassium-bicarbonate 

type groundwater originating near Yucca Mountain and 

Jackass Flats and a higher dissolved-solid, sodium-chloridesulfate-bicarbonate type groundwater near the Amargosa River 

in the western Amargosa Desert (fig. 85). Continued mineral 

dissolution along flow paths is observed in the increase of 

dissolved-solid content from the well AD-4 corridor (660 

mg/L) and Yucca Mountain and Jackass Flats area (200–315 

mg/L), to west-central Amargosa Desert (700–950 mg/L) and 

springs at Furnace Creek (760–820 mg/L) (figs. 84 and 85). 

Furthermore, the central Amargosa Desert groundwater has a 

chemical character that is intermediate between springs in the 

Furnace Creek and Ash Meadows discharge areas (fig. 85).

Based on major-ion compositions, Furnace Creek area 

discharge also could result from chemical evolution of Ash 

Meadows springs discharge. Limited data are available 

to evaluate the chemical evolution of groundwater from 

Ash Meadows springs to the Furnace Creek discharge area 

by way of a deep-carbonate flow path. Inyo-BLM 1 is the 

only well open to carbonate rocks in the central Amargosa 

Desert (fig. 84), but this 2,900-ft-deep well should represent 

conditions along the deep-carbonate flow path (fig. 82). 

Water from well Inyo-BLM 1 has a higher dissolved-solids 

concentration (995 mg/L) than Furnace Creek area discharge, 

which means that groundwater near this well would have to 

mix with a considerable fraction of more-dilute groundwater 

to result in the chemical composition of groundwater 

observed in the Furnace Creek area. In the deep-carbonate 

flow conceptualization, mixing between concentrated and 

dilute groundwater would have to occur in only carbonate 

rocks. This scenario seems less likely than the basin-fill flow 

conceptualization, which postulates that Furnace Creek area 

discharge originates from Ash Meadows groundwater basin 

through the well AD-4 corridor and from the Amargosa Desert. 

However, major-ion compositions in carbonate rocks beneath 

the Amargosa Desert are insufficient to conclusively exclude 

a flow path between Ash Meadows springs and Furnace Creek 

discharge.

Stable Isotopes

Deuterium and oxygen-18 concentrations in Furnace 

Creek cannot be differentiated from the Ash Meadows 

discharge area, Yucca Mountain–Jackass Flats wells, or 

Amargosa Desert wells. Deuterium concentrations of -104.0, 

-102.0, and -102.0 permil from Nevares, Travertine, and Texas

Springs, respectively, are bracketed by potential sources from 

Ash Meadows and AFFCR groundwater basins (fig. 86). 

Deuterium concentrations range from -104.0 to -103.0 in the 

Ash Meadows discharge area, from -108.0 to -93.2 permil 

in the Yucca Mountain–Jackass Flats area, from -104.0 

to -97.5 permil in the central Amargosa Desert, and from 

-105.0 to -92.5 permil from carbonate sites in Ash Meadows 

groundwater basin (fig. 86). Oxygen-18 concentrations of 

-13.6, -13.7, and -13.7 permil from Nevares, Travertine, and 

Texas Springs, respectively, also are within the range of sites 

in the Ash Meadows discharge area, Yucca Mountain–Jackass 

Flats area, and the western and central Amargosa Desert 

(fig. 86).

The wide range of isotopic values representing Yucca 

Mountain–Jackass Flats groundwaters indicate the large 

size and range of altitude covered by this area. The range 

of isotopic values in the central Amargosa Desert likely 

occurs because of groundwater mixing. Pumping in the 

central Amargosa Desert generally has increased between 

1950 and 2010 (fig. 30). Irrigation pumping has withdrawn 

about 555,000 acre-ft of groundwater from storage during 

1950–2010, when about 94,000 acre-ft of water re-infiltrated 

as return flow. Samples with oxygen-18 concentrations 

ranging from -13.2 to -12.4 permil in the central Amargosa 

Desert wells (sites 3, 13–16, 18, and 20 in fig. 86) appear 

evaporatively enriched, which may be attributed to pumping 

and return flow.
Simulated Predevelopment Groundwater Flow 145

sac19-4233_fig 86

Rogers

Spring

Army Well #1 

Grapevine

Spring

Cold Creek Spring

3

4

5

10

11

14

15 16

13, 18

20

21

8, 23, Big Spring

30, Crystal Pool

47

50, Nevares Spring

J-12 WW

J-13 WW

UE-25b 1 HTH

UE-25c 2 HTH

UE-29a 2 HTH

USW H-1 HTH, 25

USW H-6 HTH

USW G-2

Fairbanks Spring

USW H-4 HTH

USW H-5 HTH

USW VH-1

MR-3

Travertine and Texas Springs

27

USW G-4

-110

-105

-100

-95

-90

-16 -15 -14 -13 -12

Delta deuterium, in permil

Delta oxygen-18, in permil

Global Meteoric Water Line (Craig, 1961)

Ash Meadows discharge area

Carbonate site in Ash Meadows basin

Central Amargosa Desert

Furnace Creek area

Well AD-4 corridor

Western Amargosa Desert

Yucca Mountain-Jackass Flats area

EXPLANATION

Figure 86. Stable isotopes for sites in the Alkali Flat–Furnace Creek Ranch and Ash 

Meadows groundwater basins, Nevada and California. Water-chemistry data are compiled 

from Claassen (1973, 1985), Dudley and Larson (1976), and Thomas and others (1997), and 

are reported in Jackson and Halford (2020).

Deep-Carbonate Flow Conceptualization

The deep-carbonate flow conceptualization assumes that 

deep carbonate rocks beneath the central Amargosa Desert 

hydraulically connect the Furnace Creek area with the Ash 

Meadows discharge area (fig. 82). This conceptualization 

principally was developed using hydrochemical data with 

limited hydrologic evidence. Hydrochemical evidence 

from previous investigations is reiterated and followed by 

hydrologic and hydrochemical results from subsequent 

investigations that contradict the deep-carbonate flow path 

conceptualization.

Furnace Creek Fault Zone

The deep-carbonate flow path has been conceptualized as 

a permeable feature in IT, DVRFS.v1, and DVRFS.v2 models 

(table 1). Conceptualization and implementation of the deepcarbonate flow path was articulated clearly for the IT model: 

“The Furnace Creek fault is interpreted to act as a conduit to 

groundwater flow from the Amargosa Desert to Death Valley.” 

(IT Corporation, 1997, p. 6-15; fig. 82).

The deep-carbonate flow path from Ash Meadows 

groundwater basin to Furnace Creek was attributed 

initially to the Furnace Creek fault zone (fig. 5), which was 

conceptualized as a conduit through deep carbonate rocks from 

the Ash Meadows discharge area to Furnace Creek (Hunt and 

Robinson, 1960). The flow path was postulated in a quarterpage of text, based solely on hydrochemical similarities of 

spring waters between the Furnace Creek and Ash Meadows 

discharge areas. This argument was reiterated and expounded 

upon by assuming Furnace Creek discharge was sourced 

from Pahrump Valley, based on hydrochemical similarities 

and decreasing hydraulic potential from Pahrump to the Ash 

Meadows discharge area and to Furnace Creek (Hunt and 

others, 1966, p. B40). Arguments for flow from Pahrump 

to the Furnace Creek area through Ash Meadows were 

dismissed with a more exhaustive hydrochemical analysis and 

observation that a thick clastic confining unit isolates Pahrump 

Valley from Ash Meadows discharge area (fig. 29; Winograd 

and Thordarson, 1975, p. C91, C112). Furthermore, analysis of 

major-ion water chemistry (fig. 85) shows that springs in the 

Furnace Creek area are hydrochemically distinct from springs 

in the Ash Meadows discharge area (fig. 84). Therefore, no 

hydrologic or hydrochemical data exist to support the Furnace 

Creek fault zone as a conduit to groundwater flow.
146 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Hydrochemical Evidence

The basis for incorporating the deep-carbonate flow path 

in the DVRFS.v1 model was as follows: “Hydrochemical 

data indicate that spring flow in the major springs at the 

Furnace Creek area likely derives from the carbonate-rock 

aquifer (Winograd and Thordarson, 1975, p. C95). Similar 

hydrochemistry between spring waters at Ash Meadows 

and the Furnace Creek area (Czarnecki and Wilson, 1991; 

Steinkampf and Werrell, 2001) indicate a hydraulic connection 

between these two discharge areas through the regional 

carbonate-rock aquifer by way of large-scale fractures 

or channels in the carbonate-rock aquifer (Winograd and 

Pearson, 1976)” (Faunt, D’Agnese, and O’Brien, 2010, p. 

151). Previous arguments were accepted for the DVRFS.v2 

model with the statement, “DVRFS v. 2.0 is consistent with the 

accepted hydrogeologic interpretations of groundwater flow 

from Ash Meadows to the Furnace Creek springs through the 

southern Funeral Mountains...” (Belcher and others, 2017, 

p. 53).

The argument that “[h]ydrochemical data indicate 

that spring flow in the major springs at the Furnace Creek 

area likely derives from the carbonate-rock aquifer” (Faunt, 

D’Agnese, and O’Brien, 2010, p. 151) is not evidence for 

a deep-carbonate flow path. Springs in the Furnace Creek 

area are sourced from carbonate rocks. However, the fact 

that Furnace Creek springs are sourced from carbonate rocks 

does not mean that groundwater flow from recharge areas to 

the Furnace Creek discharge area is solely through carbonate 

rocks. Winograd and Thordarson (1975, p. C113) state clearly 

that “[f]low from the central Amargosa Desert into Death 

Valley is the most likely source of the major spring discharge 

in east-central Death Valley.” Winograd and Thordarson 

(1975, p. C112) also concluded as follows: “Therefore, on 

the basis of chemical quality of water, the spring discharge 

at the Furnace Creek Wash-Nevares springs area seems to 

come from water in the valley-fill aquifer of the central and 

northwestern Amargosa Desert.”

The argument that “[s]imilar hydrochemistry between 

spring waters at Ash Meadows and the Furnace Creek 

area...indicate a hydraulic connection between these 

two discharge areas through the regional carbonate-rock 

aquifer” (Faunt, D’Agnese, and O’Brien, 2010, p. 151) is 

not valid based on available data. The chemical character 

of Furnace Creek discharge is a sodium-sulfate-bicarbonate 

type that is distinct from Ash Meadows springs, which are 

a calcium-magnesium-sodium-bicarbonate type. Central 

Amargosa Desert groundwater has a chemical character that 

is intermediate between springs in the Furnace Creek and Ash 

Meadows discharge areas. Chemical evolution of groundwater 

from Ash Meadows springs to Furnace Creek by way of 

a deep-carbonate flow path is less plausible, based on the 

limited data available, compared to a basin-fill flow path. The 

source of discharge in Furnace Creek is inconclusive based 

on stable-isotope results. Furthermore, an argument of similar 

hydrochemistry between springs does not, by itself, indicate a 

hydraulic connection between the two discharge areas.

The basin-fill flow path was excluded previously 

because water chemistry of the central Amargosa Desert 

was characterized with limited numbers of wells. For 

example, in a rare earth element study to characterize the 

source of Furnace Creek springs (Johannesson and others, 

1997), water chemistry of the central Amargosa Desert was 

characterized using only two wells (sites 3 and 35 in fig. 84). 

Characterization of all central Amargosa Desert groundwater 

using only two wells is not representative because the water 

chemistry varies greatly (fig. 84). Using limited data from the 

central Amargosa Desert resulted in the conclusion that

 “...[rare earth element] signatures of Ash Meadows ground 

waters are similar to those of springs in the Furnace Creek 

region of Death Valley but different from shallow ground 

waters from predominantly tuffaceous alluvial deposits in the 

Amargosa Desert, perched ground waters from felsic volcanic 

rocks, and ground waters that have only flowed through the 

regional Paleozoic carbonate aquifer” (Johannesson and 

others, 1997, p. 807). Heterogeneous water chemistry and 

complex flow fields in the Amargosa Desert indicate that a 

comprehensive and integrated hydrologic and geochemical 

analysis is necessary to conclusively characterize flow to 

Furnace Creek springs.

Contradictory Results from Drilling and Numerical 

Simulation

Wells Inyo-BLM 1 and Inyo-BLM 2 (fig. 19) were 

intended to characterize the deep-carbonate flow path 

beneath the Amargosa Desert (Inyo County Yucca Mountain 

Repository Assessment Office, 2005). Well Inyo-BLM 1 was 

drilled to a depth of 2,900 ft below land surface and penetrated 

450 ft of carbonate rocks. A small transmissivity of 100 ft2/d 

was estimated from a tidal-forcing analysis (Cutillo and 

Bredehoeft, 2011). Well Inyo-BLM 2 was drilled to a depth of 

3,340 ft below land surface without encountering carbonate 

rocks (Inyo County Yucca Mountain Repository Assessment 

Office, 2007). Results from targeted drilling in the Amargosa 

Desert contradicted expectations that permeable carbonate 

rocks occur at depth.

Similar results also occurred with other wells in the 

study area, where transmissive carbonate rocks at depth were 

targeted. Wells ER-5-3-2 and UE-25p1 (JF-2a) (fig. 19) were 

drilled to depths of 5,683 and 5,923 ft below land surface, 

respectively, and penetrated low-transmissivity (100–900 ft2/d) 

carbonate rocks. Wells ER-5-4-2 and ER-8-1 (recompleted)

(fig. 19) were drilled to depths of 7,000 and 2,863 ft below 

land surface, respectively, and penetrated low-transmissivity 

(less than 1 ft2/d) volcanic and granitic rocks, respectively, 

instead of carbonate rocks. Even though a rigorous evaluation 

of deep carbonate rocks is not possible, failed attempts to find 

transmissive intervals in deep carbonate rocks indicate that a 

deep flow path through carbonate rocks is unlikely.
Simulated Predevelopment Groundwater Flow 147

The deep-carbonate flow path was not simulated by the 

DVRFS.v2 model (fig. 87), despite being discussed as the 

preferred conceptual model (Belcher and others, 2017, p. 53). 

No discharge in the Furnace Creek area originated in the Ash 

Meadows groundwater basin as simulated with the DVRFS.

v2 model. The DV3-SS model simulated groundwater flow to 

the Furnace Creek area from the Yucca Mountain area in the 

AFFCR groundwater basin and predominantly from Yucca 

Flat and the Groom Range in Ash Meadows groundwater 

basin (fig. 87).

Basin-Fill Flow Path More Probable

The basin-fill flow path between Ash Meadows 

groundwater basin and the Furnace Creek area is more 

plausible, based on available data, than a deep-carbonate flow 

path for discharge in the Furnace Creek area. The basin-fill 

flow path, which extends from the well AD-4 corridor, through 

the central Amargosa Desert, and into the Funeral Mountains, 

is consistent with hydraulic and hydrochemical evidence. The 

deep-carbonate flow path is not supported by hydraulic or 

geochemical evidence. The water chemistry of discharge in 

the Furnace Creek area clearly has evolved from the chemistry 

in the Ash Meadows discharge area and requires mixing with 

water from a non-carbonate source. Conceptual and numerical 

models of the basin-fill flow path are consistent in this study. 

In contrast, the deep-carbonate flow path conceptualization 

for the DVRFS.v2 study is not consistent with the DVRFS.v2 

model (fig. 87).

Predevelopment Water Budgets

Groundwater basins were subdivided to simulate 

water budgets where estimated flow rates were needed. 

Groundwater-flow estimates generally are needed to constrain 

groundwater-velocity estimates from underground nuclear 

tests in CAUs at the NNSS. Estimated flow rates also inform 

water availability in subareas. Groundwater basins were 

divided into subareas, where flow across subarea divides was 

minimal, to minimize sensitivity of flow-rate estimates to 

specific divides (fig. 88). These divisions were suggested by 

mapped pathlines (fig. 80), water-level contours, and existing 

mapped groundwater-basin boundaries. Flow rates were 

simulated and balanced using zones that extended vertically 

from the water table to the model base in each subarea. 

Simulated recharge, discharge, and net flows between subareas 

were totaled with ZONEBUDGET (Harbaugh, 1990) and 

reported for each subarea.

Pahute Mesa–Oasis Valley Groundwater Basin

Most of the recharge in the PMOV groundwater basin is 

derived from Pahute Mesa (fig. 45). Total simulated recharge 

in the PMOV groundwater basin is 5,900 acre-ft/yr (table 11; 

fig. 88). Simulated recharge in the Pahute Mesa and Timber 

Mountain areas is 4,130 acre-ft/yr, whereas simulated recharge 

in the northwestern subarea is 1,060 acre-ft/yr. A smaller 

amount (600 acre-ft/yr) of recharge occurs in Kawich Valley 

from the Belted and Kawich Ranges. A small amount of 

recharge also is generated locally in the Oasis Valley discharge 

area (110 acre-ft/yr).

More than 90 percent of the groundwater discharging in 

Oasis Valley is derived from recharge sourced at Pahute Mesa 

and Timber Mountain (fig. 88). Total simulated discharge 

in Oasis Valley is 6,130 acre-ft/yr. The 5,530 acre-ft/yr of 

groundwater inflow from Pahute Mesa and Timber Mountain 

areas accounts for locally derived recharge and inflows from 

the north, west, and east. Bullfrog Hills contributes a small 

amount (60 acre-ft/yr) of groundwater flow to Oasis Valley.

Ash Meadows Groundwater Basin

Total simulated recharge in the Ash Meadows 

groundwater basin is about 21,600 acre-ft/yr (table 11; fig. 88). 

About 80 percent (17,400 acre-ft/yr) of the recharge in Ash 

Meadows groundwater basin occurs in the Spring Mountains 

and Sheep Range, which are the highest altitude ranges in the 

study area. Less than 20 percent (3,670 acre-ft/yr) of the total 

recharge is derived from highland areas in the northern part of 

the Ash Meadows groundwater basin.

Less than 3 percent of predevelopment flow in Ash 

Meadows groundwater basin moves through Yucca Flat 

(fig. 88). About 190 acre-ft/yr of groundwater moves into 

northern Yucca Flat from Emigrant Valley. Groundwater flow 

through the Eleana Range into western Yucca Flat is about 

60 acre-ft/yr, whereas groundwater flow through the Halfpint 

Range into eastern Yucca Flat is about 10 acre-ft/yr. Simulated 

recharge derived from highland areas that bound Yucca Flat 

totals 230 acre-ft/yr. Total simulated groundwater flow from 

southern Yucca Flat through carbonate rocks is about 530 

acre-ft/yr.

Groundwater flow in the Ash Meadows groundwater 

basin converges near the Specter Range (fig. 88). About 

17,000 acre-ft/yr moves westward from recharge areas 

spanning from the Spring Mountains in the south to the Sheep 

Range in the east. About 3,700 acre-ft/yr of groundwater 

moves south-southwest from Yucca Flat and the Pahranagat 

and Groom Ranges.

Simulated water budgets indicate that the Ash Meadows 

discharge area receives groundwater primarily from the Ash 

Meadows groundwater basin, with a minor contribution from 

the PDVS groundwater basin (fig. 88). About 18,290 acre-ft/

yr of groundwater moves southwest into the Ash Meadows 

discharge area. Simulation results indicate that about 180 

acre-ft/yr of groundwater moves northward from Pahrump 

Valley to the Ash Meadows discharge area. This result is 

speculative and uncertain because of a lack of water-level data 

in wells to constrain flow between Pahrump Valley and the 

Ash Meadows discharge area.
148 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 87

Fortymile Wash

Amargosa

A

R

margosa R

Fortymile Wash

Amargosa

A

R

margosa R

Indian 

Springs

Mercury Amargosa

Valley

Beatty

Shoshone

Tecopa

Furnace

Creek

Pahrump

Indian 

Springs

Mercury Amargosa

Valley

Beatty

Shoshone

Tecopa

Furnace

Creek

Pahrump

Furnace Creek fault zone

0 40 MILES

0 20

20

40 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116° 115° 117° 116° 115°

DVRFS.v2 model DV3-SS model

Devils Hole Devils Hole

ALKALI FLAT–

FURNACE CREEK

RANCH

ALKALI FLAT–

FURNACE CREEK

RANCH

PAHUTE MESA–

OASIS VALLEY

PAHRUMP TO DEATH 

VALLEY SOUTH

ASH MEADOWS

BULLFROG 

HILLS

PAHUTE MESA–

OASIS VALLEY

PAHRUMP TO DEATH 

VALLEY SOUTH

ASH MEADOWS

BULLFROG 

HILLS

Pahute 

Mesa

Oasis Valley

Belted Range

Kawich Range

Gold 

Flat

Yucca 

Mountain

Funeral Mountains

Black Mountains

Death Valley

Death Valley

Spring 

Mountains

Groom 

Range Pahranagat Range

Sheep Range

Pintwater Range

Desert Range

Yucca 

Flat

Frenchman 

Flat

Cactus 

Range

Nopah Range

Pahute 

Mesa

Oasis Valley

Belted Range

Kawich Range

Gold 

Flat

Yucca 

Mountain

Funeral Mountains

Black Mountains

Spring 

Mountains

Groom 

Range Pahranagat Range

Sheep Range

Pintwater Range

Desert Range

Yucca 

Flat

Frenchman 

Flat

Cactus 

Range

Nopah Range

INYO

NYE

SAN BERNADINO

CLARK

LINCOLN

CALIFORNIA

NEVADA

INYO

NYE

SAN BERNADINO

CLARK

LINCOLN

CALIFORNIA

NEVADA

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Fault

Ash Meadows National Wildlife 

Refuge

Groundwater-flow path, representing 50 acre-feet per year—from 

Furnace Creek discharge area to 

the following recharge areas

Path that originates in Ash 

Meadows groundwater basin

Path that originates in Alkali 

Flat–Furnace Creek Ranch or 

Pahute Mesa–Oasis Valley 

groundwater basin

Figure 87. Flow-weighted paths from Furnace Creek discharge area to contributing recharge areas in the Death Valley 

Regional Flow System version 2 model (DVRFS.v2) and Death Valley version 3 steady-state model (DV3-SS), in the study 

area, Nevada and California.
Simulated Predevelopment Groundwater Flow 149

sac19-4233_fig 88

Fortymile Wash

Amargosa River Chin a Ranch

Wash

Amargosa River

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

CP

basin

Frenchman

Flat

Jackass

Flats

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Saratoga 

Spring

area

Rainier

Mesa

Devils Hole 

AD-4

2,550

240

30

660

4,860

40

30

60 

180

3,700

20

40

190

110

6,860

880

600 

5,530

230 10

17,000

530

2,570

10

60

60 

540 

20

300

2,520

18,290

6,380

340

60

20

10 

10 

20

20,280

40 

480

80

40

40

60

950

910

620

5,540 440

20

2,490

390

13,190

830

0

20,280

18,260

60

700

17,400

440

120

20

70

6,430

50

580

1,790

0

2,840

0

120

0

30

0

3,670

0

1,060 0

600

0

80

6,130

110

0

4,130

0

100

0

230

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

EXPLANATION

EXPLANATION

Observation well or site

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

60

40

60

Zone used to compute 

inflows and outflows 

between geographic areas

Top number is simulated 

recharge, from infiltration 

of precipitation, within 

zone and bottom number is 

simulated predevelopment 

discharge, from springs 

and evapotranspiration 

areas, in zone. Values from 

DV3-SS model are in 

acre-feet per year and not 

rounded so that budgets 

balance between zones.

Direction and amount of flow 

into or out of zone, in 

acre-feet per year. Arrows 

not shown where less than 

5 acre-feet per year moves 

across boundaries.

Emigrant 

Valley

Shoshone 

Mountain

Stewart 

Valley

Dumont

Dunes

Figure 88. Predevelopment water budgets within and between geographic areas in the study area from the Death 

Valley version 3 steady-state model (DV3-SS), Nevada and California.
150 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Alkali Flat–Furnace Creek Ranch Groundwater 

Basin

Total simulated recharge in the AFFCR groundwater 

basin is less than 5,000 acre-ft/yr (table 11; fig. 88). Slightly 

more than one-half (2,840 acre-ft/yr) of the recharge occurs 

on Timber, Yucca, and Shoshone Mountains (fig. 45). About 

1,800 acre-ft/yr infiltrates along the Amargosa River and 

Fortymile Wash during ephemeral flows in the Amargosa 

Desert (figs. 45 and 88).

Groundwater moves laterally into the Amargosa Desert 

across six of the eight boundaries between adjacent zones 

(fig. 88). Simulated flow into the Amargosa Desert (AFFCR 

groundwater basin) principally comes from the Ash Meadows 

groundwater basin (2,790 acre-ft/yr) and Yucca and Shoshone 

Mountain areas (2,570 acre-ft/yr). Flow from the PMOV 

groundwater basin near Beatty, Bullfrog Hills, the Gravity 

Fault south of the well AD-4 corridor, and Greenwater Range 

are minor and contribute less than 400 acre-ft/yr to the 

Amargosa Desert.

Most groundwater that enters the Amargosa Desert 

moves westward toward the Furnace Creek area (fig. 88). Total 

simulated discharge in the Furnace Creek area is 6,430 acre-ft/

yr. About 6,380 acre-ft/yr of groundwater moves from the 

Amargosa Desert through the Funeral Mountains to discharge 

at Furnace Creek. About 50 acre-ft/yr is recharged locally in 

the Funeral Mountains near Furnace Creek.

Groundwater movement into Franklin Lake occurs from 

the Amargosa Desert, Greenwater Range, and Ash Meadows 

discharge area (fig. 88). Total simulated discharge at Franklin 

Lake is 440 acre-ft/yr, with most of this discharge sourced 

from the Amargosa Desert. The Greenwater Range and Ash 

Meadows discharge area directly contribute less than 10 

percent of the discharge at Franklin Lake.

Pahrump to Death Valley South Groundwater 

Basin

Simulated recharge in the PDVS groundwater basin 

totals 22,930 acre-ft/yr (fig. 88), but net recharge totals 

22,210 acre-ft/yr (table 11) after 720 acre-ft/yr of re-infiltrated 

surface flow near Dumont Dunes is subtracted. Most of the 

recharge occurs in the Spring Mountains. About 400 acre-ft/

yr is recharged in the Nopah and Resting Spring Ranges, with 

most recharge occurring in the Nopah Range (fig. 45). Most 

of the discharge from the Saratoga Spring area is re-infiltrated 

surface flow near Dumont Dunes (fig. 45), and the functional 

terminus of the PDVS groundwater system is the Lower 

Amargosa area.

More than 60 percent of the groundwater entering 

Pahrump and Stewart Valleys is discharged locally at springs 

and in evapotranspiration areas (fig. 88). Groundwater inflow 

to Pahrump and Stewart Valleys from local recharge and 

upgradient flow from the Spring Mountains totals 20,280 

acre-ft/yr. Total simulated discharge in Pahrump and Stewart 

Valleys is slightly more than 13,000 acre-ft/yr.

Less than 40 percent (7,740 acre-ft/yr) of groundwater 

entering Pahrump and Stewart Valleys moves southwest to 

discharge areas downgradient of the Nopah Range (fig. 88). 

Most of the groundwater moves through the Nopah Range 

into Chicago Valley. This groundwater either discharges in 

Chicago Valley or moves southward to discharge along the 

Amargosa River. Groundwater that enters California Valley 

either discharges at springs locally in the valley or moves 

downgradient to discharge areas near Tecopa, California.

Simulation results indicate that groundwater discharging 

in the Saratoga Spring area is derived from California Valley 

and from re-infiltrated surface flow near Dumont Dunes 

(fig. 88). More than 70 percent of the discharge in the Saratoga 

Spring area is local recharge from re-infiltrated surface flow 

from the Amargosa River. California Valley contributes about 

40 acre-ft/yr of groundwater flow to the Saratoga Spring area.

Rainier Mesa Groundwater Sub-Basin

Recharge to Rainier Mesa is limited to 100 acre-ft/

yr across a 50 mi2 area (fig. 88), even though Rainier Mesa 

receives high rates of precipitation. Most of the precipitation 

is not recharged locally because of low-permeability rocks, 

which cause most recharge to be redistributed downslope 

(fig. 16). Recharge rates in Rainier Mesa averaged 0.003 ft/yr 

and were limited by low permeabilities of the zeolitized tuffs. 

This in-place recharge moves downgradient and about 30, 60, 

and 10 acre-ft/yr moves into the PMOV, Ash Meadows, and 

AFFCR groundwater basins, respectively.

Effects of Groundwater Development

Effects of groundwater development were characterized 

with calibrated DV3-AM-AFFCR and DV3-PDVS models. 

Extents of water-level declines from pumping were mapped 

throughout the study area. Sources of pumped water were 

differentiated between groundwater-storage depletion, capture 

of discharge from springs and ET areas, and return flow. 

Reductions in natural discharges from predevelopment to 

2018 were quantified by discharge areas in Oasis Valley, Ash 

Meadows, Furnace Creek area, Pahrump Valley, and Lower 

Amargosa area. Effects of pumping centers and local injection 

on water levels in Devils Hole were differentiated between 

1950 and 2018.
Effects of Groundwater Development 151

Extent of Water-Level Declines

Extents of water-level declines throughout the study 

area in 2018 are shown where simulated declines equaled or 

exceeded 1 ft (fig. 57). Using simulation results to estimate the 

extent of pumping effects was necessary where effects have 

not been measured or are obscured. For example, simulated 

water levels declined in California Valley where no wells have 

been inventoried or drilled (fig. 57). Simulated declines of 

1–2 ft in Jackass Flats likely occurred (fig. 57) but are masked 

by water-level rises from recharge that exceed declines 

from pumping (fig. 36). Estimating extents of pumpingaffected areas with simulated water levels is less certain than 

measuring water levels in wells and primarily suggests where 

monitoring is needed.

Drawdowns from pumping in the central Amargosa 

Desert, Jackass Flats, eastern NNSS, and Indian Springs have 

coalesced into a 2,200 mi2 area (fig. 57). This area extends 

west to east from the Furnace Creek area to the base of the 

Sheep Range and south to north from the southern Funeral 

Mountains to northern Yucca Flat. Drawdowns from multiple 

pumping centers have combined because relatively contiguous 

areas have transmissivities greater than 10,000 ft2/d (fig. 68). 

Basin fill of the central Amargosa Desert, volcanic and 

carbonate rocks of Jackass Flats, and the carbonate-rock 

megachannel are three notable areas where simulated 

transmissivities are high and empirically confirmed with 

aquifer-test results.

Drawdowns from pumping in Pahrump Valley have 

affected most, if not all, transmissive basin fill and carbonate 

rocks in the PDVS groundwater basin, where drawdowns 

extend over an area of 1,400 mi2 (fig. 57). Drawdowns were 

constrained to the southwest by low-permeability rocks that 

bound transmissive rocks between the Amargosa River and 

the Spring Mountains (fig. 32). Simulated drawdowns north 

of Shoshone and in Chicago Valley are relatively accurate 

based on comparisons with measured declines in wells 

022N007E13L01S and Hwy 127 MM21-1 (fig. 61). Simulated 

drawdowns do not extend into the Tecopa area (fig. 57). This 

result is less certain because groundwater levels have not been 

measured near Tecopa.

Drawdowns from isolated areas of groundwater 

development have limited extents of less than 5 mi (fig. 57). 

Drawdowns in Emigrant Valley, Pahute Mesa, and south 

of Bullfrog Hills are typical examples of isolated pumping. 

Drawdowns greater than 1 ft were not simulated around 

Furnace Creek area pumping wells. These pumping wells 

are close to Travertine and Texas Springs, which has resulted 

in most of the pumped water being derived from captured 

spring discharge rather than groundwater storage. Effects from 

pumping in Indian Springs are not isolated, as conceptualized, 

and contribute to water-level declines in the megachannel 

(fig. 57).

Sources of Pumped Water 

Simulation results for sources of pumped water were 

differentiated between groundwater-storage depletion, return 

flow, and capture of discharge from springs and ET areas. 

Cumulative pumping volumes totaled 50, 19, and 31 percent 

from storage depletion, return flow, and capture, respectively, 

during groundwater development between 1910 and 2018. 

Sources differed considerably by groundwater basin as 

groundwater development occurred (fig. 89). Cumulative 

capture (1913–2018) exceeded cumulative storage depletion 

in the PDVS groundwater basin, but storage depletion 

annually exceeded capture during peak pumping between 

1952 and 1985. Storage depletion supplied greater than 90 

percent of pumped water from AFFCR and Ash Meadows 

groundwater basins (fig. 89A). These groundwater basins were 

combined because pumping from either basin can capture 

predevelopment discharges in both basins. Return flow 

consisted of water from storage depletion and capture that had 

been pumped during previous years. Storage depletion and 

capture constituted 61 and 39 percent of cumulative return 

flow in the study area, respectively.

Capture was substantial where groundwater development 

occurred near springs in Pahrump Valley and the Ash 

Meadows discharge area. Pumping wells in Pahrump Valley 

mostly were within 5 mi of Bennetts and Manse Springs prior 

to 1946 (figs. 29 and 32) and pumped water principally was 

captured spring discharge (fig. 89). Pumping by Cappaert 

Enterprises was within 5 mi of springs in the Ash Meadows 

discharge area and about one-half of the pumped water was 

capture.

Reductions in Natural Discharges 

Discharges from springs and ET areas decreased in 

response to declining groundwater levels from pumping 

(table 13). Simulated discharges in 2018 were less than 80 

percent of discharges prior to development. More than 80 

percent of the simulated decline in predevelopment discharge 

occurred in Pahrump Valley and primarily was capture of 

discharges from Bennetts and Manse Springs (fig. 62).

Simulated captures in the Franklin Well area and Chicago 

Valley were both more than 80 percent of predevelopment 

discharge (table 13), indicating that extinction depths were 

underestimated. These ET areas were assigned a uniform 

extinction depth of 5 ft. Simulated water levels in the Franklin 

Well area and Chicago Valley declined between 10 and 15 

ft after 1993, but vegetation appears little changed between 

1994 and 2018. Simulating capture of discharge by ETGW with 

a fixed extinction depth is an approximation that does not 

account for growth of roots.
152 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 89

Projected Projected

Groundwater withdrawals, in thousands of acre-feet per year 0

10

20

30

0

10

20

30

40

50

0

10

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

A. Alkali Flat-Furnace Creek Ranch and Ash Meadows

B. Pahute Mesa-Oasis Valley

C. Pahrump to Death Valley South

Year

EXPLANATION

Storage depletion

Return flow

Capture

Predevelopment discharge

 Figure 89. Total annual groundwater withdrawals by groundwater-storage depletion, 

return flow, and capture of discharge from springs and evapotranspiration areas by 

groundwater basins Alkali Flat–Furnace Creek Ranch and Ash Meadows (A), Pahute 

Mesa–Oasis Valley (B), and Pahrump to Death Valley South (C), in the study area, 

1910–2018, with withdrawal estimates from 2010 projected to 2018.
Effects of Groundwater Development 153

Table 13. Simulated discharges by discharge area for predevelopment (DV3-SS 

model), 2018 (DV3-AM-AFFCR or DV3-PDVS model), and projected future conditions in 

2100 (DV3-PRED model), in the study area, Nevada and California.

[Groundwater basin: AFFCR, Alkali Flat–Furnace Creek Ranch; PDVS, Pahrump to Death Valley 

South; PMOV, Pahute Mesa–Oasis Valley. Annual simulated discharge—2018 and 2100: Pumping rates from 2010 were either projected through 2018 or 2100. Abbreviations: DV3-AM-AFFCR 

model, Death Valley version 3 stress-response model simulating groundwater development in the Ash 

Meadows, Alkali–Furnace Creek Ranch, and Pahute Mesa–Oasis Valley groundwater basins; DV3-

PDVS model, Death Valley version 3 stress-response model simulating groundwater development in 

the Pahrump to Death Valley South groundwater basin; DV3-PRED model, Death Valley version 3 

predictive model; DV3-SS model, Death Valley version 3 stress-response model simulating steadystate (predevelopment) conditions]

Groundwater 

basin Discharge area

Annual simulated discharge 

(acre-feet)

Predevelopment 2018 2100

AFFCR Furnace Creek area 1,2 6,300 6,100 5,900

Franklin Well area 3 330 50 10

Franklin Lake 1 300 300 200

Death Valley playa 1 100 100 100

Ash Meadows Ash Meadows with Amargosa Flat 18,500 18,000 17,400

Indian Springs 700 580 530

PMOV Oasis Valley 4 6,100 6,000 6,000

PDVS Pahrump Valley with Stewart Valley 5 13,200 3,300 4,900

Chicago Valley 3 400 10 0

Shoshone area 2,100 2,000 2,000

Tecopa/California Valley area 6,300 6,100 6,100

Saratoga Spring area—NET 6 310 310 310

Death Valley playa 1 40 40 40

TOTAL 54,700 42,900 43,500

1

 Simulated predevelopment discharges from playas assume groundwater-evapotranspiration rates 

of 0.001 foot per year.

2

 Simulated discharges from Furnace Creek Wash include diversions.

3

 Simulated discharges in 2018 and 2100 are biased low because extinction depths are underestimated.

4

 Simulated drawdowns of less than 0.5 feet in Beatty captured about 100 acre-feet of discharge in 

Oasis Valley.

5

 Simulated discharges include Bennetts and Manse Springs and evapotranspiration areas in Pahrump and Stewart Valleys.

6

 Net discharge subtracts 720 acre-feet per year (1 cubic foot per second) of return flow from Amargosa River downstream of Dumont Dunes streamgage (USGS 10251375).
154 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Simulated discharge in 2018 from the Ash Meadows 

discharge area decreased by 3 percent, or 500 acre-ft/yr, 

with more than 300 acre-ft/yr from springs. Captured spring 

discharges supplied about one-half of the pumpage for 

Cappaert Enterprises, but capture varied markedly between 

springs (fig. 71). Pumping captured all discharge from Jack 

Rabbit Spring during summer months from 1972 to 1977. 

However, average discharge from Big Spring decreased by 

20 percent and seasonally fluctuated 10 percent owing to 

pumping by Cappaert Enterprises (fig. 71). Maximum capture 

of all spring discharge occurred in August 1971 when well 

Spring Meadows 6 pumped 1,400 gal/min (3.0 ft3/s) (figs. 37

and 38). More than 90 percent of the water pumped from well 

Spring Meadows 6 was captured discharge from Crystal Pool, 

which is within 1,000 ft of well Spring Meadows 6 (Dudley 

and Larson, 1976).

Pumping in the central Amargosa Desert minimally 

affected discharges from Travertine and Texas Springs in the 

Furnace Creek area (fig. 90). Combined simulated discharges 

from Travertine and Texas Springs decreased by a total of 

0.24 ft3/s (170 acre-ft/yr) between predevelopment and 2018. 

Nearly all simulated capture from these springs were caused 

by local pumping in the Furnace Creek area that started 

in 2009. Measured discharges were not easily interpreted 

because of missing records and shifts from earthquakes 

that introduced ambiguity. Combined measured discharges 

from Travertine and Texas Springs decreased from 2.4 ft3/s 

(1,740 acre-ft/yr) to 2.0 ft3/s (1,450 acre-ft/yr) between 1964 

and 1990. The observed decrease is difficult to attribute to 

a particular stress because discharges only were measured 

once during this 25-year period. Discharges were measured 

continuously for less than 3 years during the 1990s before 

earthquakes perturbed spring discharges (fig. 90). Combined 

discharge from Travertine and Texas Springs increased 0.3 

ft3/s (220 acre-ft/yr) in response to the Landers/Little Skull 

Mountain earthquake and earthquake effects dissipated after a 

decade (Cutillo and Ge, 2006). Restoration activities, such as 

restoring spring runs from Travertine and Texas Springs, in the 

Furnace Creek area also perturbed discharges between 2006 

and 2008.

Ash Meadows and Devils Hole

Effects of individual pumping centers on water levels in 

Devils Hole were estimated with calibrated DV3-AM-AFFCR 

and DV3-PDVS models. Pumping wells were grouped into 11 

pumping centers by geography and NNSS operational units 

(table 14). The central Amargosa Desert, Pahrump Valley, and 

Cappaert Enterprises were grouped as major pumping centers 

(fig. 91). Pumping from Ash Meadows groundwater basin 

was differentiated further between Crystal, Indian Springs, 

and the megachannel (fig. 91). Pumping from wells in the 

megachannel was grouped separately from nearby wells 

outside the megachannel because of disproportionate effects 

of pumping on water levels in Devils Hole. Net pumpage from 

pumping centers and its effect on water levels in Devils Hole

between 1968 and 2018 are shown in table 14. Simulated 

results are not shown prior to 1969 because limited data are 

available in Devils Hole prior to 1969 and measurable waterlevel declines occurred after 1969.

Water-level changes in Devils Hole were simulated 11 

times with pumping and return flows from a single pumping 

center in each simulation. Individual water-level changes 

from 11 simulations were summed and compared to the total 

simulated change from all pumping in the calibrated DV3-

AM-AFFCR model. The summation of individual simulations 

did not equal total simulated changes from the calibrated 

DV3-AM-AFFCR model (fig. 92). Results differed because 

captures from springs and ET areas were non-linear and 

depended on total pumpage. The fact that Jack Rabbit Spring

went dry during summer from 1970 to 1977 is an example of 

a non-linear response (fig. 71). Individual water-level changes 

were scaled so that the summation of individual simulations 

equaled simulated changes from the calibrated DV3-AMAFFCR model. Scaling fractions varied with time and ranged 

from 1.15 to 0.72 during 1984 and 2018, respectively (fig. 92).

Only pumping centers in the central Amargosa Desert 

and Ash Meadows groundwater basin measurably affected 

water levels in Devils Hole (table 14). Pumping from Beatty, 

Pahrump Valley, and Pahute and Buckboard Mesas did 

not affect water levels in Devils Hole because areas of low 

transmissivity intervene (figs. 29 and 72). Jackass Flats did not 

affect water levels in Devils Hole because pumping was distant 

and pumped volumes were small relative to aquifer storage 

(table 14). Furnace Creek area did not affect water levels in 

Devils Hole because pumping was distant and pumped wells 

captured nearby discharge from Travertine and Texas Springs.

Pumping by Cappaert Enterprises and the NNSS inside 

the megachannel predominantly affected water levels in Devils 

Hole between 1969 and 1980 (fig. 92). However, residual 

effects of pumping from the megachannel have persisted 

for decades after pumping ceased. Maximum water-level 

declines of 2.5 ft occurred during the 1970s, where 80 percent 

of the decline was due to pumping by Cappaert Enterprises. 

Pumping by Cappaert Enterprises accounted for 25 percent of 

the anthropogenic water-level decline in Devils Hole in 2018, 

40 years after pumping ceased. Pumping by the NNSS inside 

the megachannel accounted for, on average, 20 percent of the 

anthropogenic water-level decline in Devils Hole during the 

1970s. Although most of the pumping in the NNSS occurred 

prior to 1993, NNSS pumping inside the megachannel 

accounted for 25 percent of the water-level decline in 

Devils Hole from 1993 to 2018. Water-level declines in 

2018 of less than 0.1 ft from Crystal are small (fig. 92), 

but disproportionately large for average pumping rates of 

40 acre-ft/yr (table 14). Pumping in Crystal exaggeratedly 

affected water levels in Devils Hole because pumpage came 

from the megachannel (fig. 91).
Effects of Groundwater Development 155

Hector Mine

Start of local pumping

Landers/Little

Skull Mountain

B. USGS 362728116501101 027N001E23BS01S Texas Springs

A. USGS 362630116494701 243 027N001E26AS00S Travertine Springs

0

1

2

0

1

Spring discharge, in cubic feet per second

1950 1960 1970 1980

Year

1990 2000 2010 2020

Measured

Simulated

Earthquake

EXPLANATION

Figure 90. Measured and simulated discharges from Travertine (A) and Texas (B) Springs 

in the Furnace Creek area, California, 1950–2018. Simulated discharges do not account for 

earthquake effects.

Table 14. Pumping centers; net pumpage volumes, 1969–2018; and effect of pumping centers on water levels in Devils Hole, in 

the study area, Nevada and California.

[Groundwater basin: AFFCR, Alkali Flat–Furnace Creek Ranch; PDVS, Pahrump to Death Valley South; PMOV, Pahute Mesa–Oasis Valley. Symbols:

<, less than; –, not applicable because simulated drawdown was not estimated]

Groundwater 

basin Pumping center

Volume of net pumpage,

1969–2018 

(acre-feet)

Simulated water-level decline in 

Devils Hole (feet)

Year of maximum 

water-level decline 

2018 Maximum in Devils Hole

Ash Meadows Cappaert Enterprises 40,000 0.36 2.09 1972

AFFCR Central Amargosa Desert 540,000 0.48 0.48 2018

Ash Meadows Inside megachannel 15,000 0.31 0.46 1995

Ash Meadows Crystal 2,000 0.06 0.23 1987

Ash Meadows Outside megachannel 38,000 0.12 0.14 2007

Ash Meadows Indian Springs 28,000 0.08 0.08 2018

AFFCR Jackass Flats 6,000 <0.01 <0.01 –

AFFCR Beatty 26,000 <0.01 <0.01 –

PMOV Pahute and Buckboard Mesas 11,000 <0.01 <0.01 –

PDVS Pahrump Valley 1,064,000 <0.01 <0.01 –

AFFCR Furnace Creek area 2,000 <0.01 <0.01 –
156 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 91

Fortymile Wash

Amargosa River

Amargosa River

Chin a Ranch

Wash

95

95

93

15

373

190

127

318

375

582

Beatty

Amargosa

Valley

Shoshone

Tecopa

Pahrump

Furnace

Creek

Indian

Springs

Mercury

Las

Vegas

LINCOLN CO.

CLARK CO.

NYE CO.

INYO CO. CALIFORNIA

NEVADA

SAN BERNADINO CO.

Cactus

Range

Pahute Mesa

Oasis Valley

Funeral Mountains

Black Mountains

Greenwater Range

Amargosa Desert

Spring Mountains

Groom

Range 

Sheep Range

Pintwater Range

Specter Range

Halfpint Range

Eleana Range

Chicago Valley

Nopah Range

Gold 

Flat

Kawich

Valley

Yucca

Flat

Climax

Mine

Rainier

Mesa

CP

basin

Frenchman

Flat

Timber

Mountain

Yucca

Mountain

Bare

Mountain

Indian

Springs

Valley

Three

Lakes

Valley

Franklin

Lake

Pahrump

Valley

Las Vegas

Valley

Rest ni g Spring Range

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

BULLFROG

HILLS

PAHRUMP TO 

DEATH VALLEY

SOUTH

Belted Range

Kawich Range

Pahra nagat Range

Desert Range

Spotted Range

California Valley

Death Valley

Devils Hole 

AD-4

Pahrump 

Valley

Indian

Springs

Pahute and 

Buckboard 

Mesas

Beatty

Jackass 

Flats

Central 

Amargosa 

Desert

Furnace 

Creek area

Crystal

Cappaert 

Enterprises

Inside 

megachannel

Outside 

megachannel

0 20 MILES

0 10

10

20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Data. Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

117°

37°

36°

116°30' 116° 115°30' 115°

37°

30'

36°

30'

Dumont

Dunes

EXPLANATION

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Extent of megachannel, 

as delineated in this 

study using a 

transmissivity of 20,000 

feet squared per day

Pumping center and

identifier

Well with pumping rate 

less than 100 acre-feet 

per year

Well with pumping rate 

greater than 100 

acre-feet per year— 

wells categorized by 

pumping effect on water 

levels in Devils Hole

No effect

Likely has an effect

Measureable effect 

Likely does not have effect 

—well open to basin fill 

or volcanic rocks in or 

near megachannel

Beatty

Figure 91. Pumping centers analyzed for affecting water levels in Devils Hole, Nevada and California.
Effects of Groundwater Development 157

sac19-4233_fig 92

Unscaled summation of individual simulations

Year

0

10

20

Net pumpage, in acre-feet per year

1950 1960 1970 1980 1990 2000 2010 2020

−3

−2

−1

0

1

2

Water-level change in Devils Hole, in feet

Crystal

Indian Springs

Outside megachannel

Inside megachannel

Central Amargosa Desert

Cappaert Enterprises

Measured without natural fluctuations

EXPLANATION

A

B

Figure 92. Annual net pumpage by pumping center (A) and water-level changes in 

Devils Hole by pumping center, as simulated with the Death Valley version 3 stressresponse model simulating groundwater development in the Ash Meadows, Alkali 

Flat–Furnace Creek Ranch, and Pahute Mesa–Oasis Valley groundwater basins (B), 

Nevada and California, 1950–2018.
158 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Water levels in Devils Hole declined rapidly in the early 

1970s, recovered through the 1980s, and have declined slowly 

and steadily since the 1990s from pumping in the central 

Amargosa Desert (fig. 92). Pumped volumes from the central 

Amargosa Desert were an order of magnitude greater than 

pumped volumes from Cappaert Enterprises (table 14), but 

effects on water levels in Devils Hole were attenuated by 

limited hydraulic connection through the well AD-4 corridor. 

Water levels in Devils Hole have declined at a rate of 0.1 ft 

per decade from pumping in the central Amargosa Desert 

during 1998–2018. Pumping in the central Amargosa Desert 

accounted for a third of anthropogenic water-level decline in 

Devils Hole during 2018 (fig. 92).

Injection in Devils Hole Well (AM-5) elevated water 

levels in Devils Hole about 0.5 ft prior to the discontinuation 

of injections in 1977 (fig. 93). Effects of injection in Devils 

Hole Well (AM-5) were estimated by removing injection 

from the calibrated DV3-AM-AFFCR model and simulating 

water-level changes in Devils Hole. Results from the model 

simulating injection were subtracted from model results 

without injection to estimate effects of injection in Devils 

Hole Well (AM-5) on water levels in Devils Hole. Differences 

in fit between measured and simulated water levels in Devils 

Hole prior to and during injection suggest that injection rates 

were more variable than reported (Larson, 1975). This is 

because measured and simulated monthly water-level changes 

track well prior to injection and poorly during simulated 

injection. Water levels in Devils Hole Well (AM-5) also vary 

greatly (fig. 39), which suggests that the injection rate was not 

constant with time.

Potential Effects of Future 

Groundwater Development

Potential effects of future groundwater development on 

water levels and spring discharges were estimated with the 

DV3-PRED model (Jackson and Halford, 2020). Pumping 

history and temporal discretization in the DV3-PRED model 

differed from the DV3-AM-AFFCR and DV3-PDVS models. 

Pumping changed annually in all groundwater basins from 

1913–2010 in the DV3-PRED model. Annual pumping rates 

during 2011–2018 were projected from pumping rates in 2010 

(Elliott and Moreo, 2018). All pumping scenarios simulated 

pumping, water-level changes, and capture of discharges from 

1913–2018 before solving for predicted changes. Simulated 

water-level changes in Devils Hole from DV3-AM-AFFCR 

(fig. 92) and DV3-PRED (fig. 94) models differ because of 

use of monthly and annual stress periods during pumping by 

Cappaert Enterprises, respectively. These temporal pumping 

differences dissipated during recovery between 1980 and 

2000, and simulated water levels from both DV3-AM-AFFCR 

and DV3-PRED models were quite similar between 2000 and 

2018 (fig. 94).

Water-level changes in Devils Hole from pumping were 

simulated with steady-pumping and no-pumping scenarios that 

simulated changes from 2019–2100 (fig. 94). Pumping rates 

from 2010 were projected from 2019–2100 in the steadypumping scenario. All pumping ceased in 2019 and recovery 

was simulated in the no-pumping scenario. Simulated water 

levels in Devils Hole declined 1.5 ft and rose 0.1 ft from 

2019–2100 in the steady-pumping and no-pumping scenarios, 

respectively (fig. 94). 

Prolonged water-level recovery responses in Devils Hole

were observed from Cappaert pumping during 1980–2018 

and from results of the hypothetical no-pumping scenario 

during 2019–2100. Prolonged water-level recovery responses 

to pumping are typical in the megachannel. For example, 

prolonged recovery also has been observed in Tracer Well 

3 during recovery from Cappaert pumping (fig. 70) and 

recovery from the ER-6-1-2 main MWAT (fig. 67). Prolonged 

recovery occurs because large volumes of groundwater were 

withdrawn from carbonate rocks in the megachannel. Pumping 

minimally decreases water levels and induces little extra 

flow from surrounding rocks to offset storage depletion in the 

megachannel. Substantial groundwater-storage depletion from 

the Ash Meadows groundwater basin (fig. 89) has resulted 

in a 2-ft water-level decline throughout the carbonate-rock 

megachannel by 2018 (fig. 57).

Water-level changes in Devils Hole simulated with the 

DV3-PRED model likely are biased towards minimum change 

for given pumping rates because of assumptions regarding 

natural fluctuations. Water levels are affected by long-term 

natural fluctuations; however, simplified assumptions were 

made to quantify this natural variability so that hydraulic 

properties could be estimated (fig. 40). Long-term natural 

fluctuations in Devils Hole were not estimated uniquely and 

were biased toward a minimum rise of 1 ft between 1973 and 

2018. A rise of 1.5 ft between 1973 and 2018 could have been 

estimated in Devils Hole, which would have caused drawdown 

estimates to be 0.5 ft greater or total 2 ft in 2018, instead of 

the 1.5 ft of drawdown currently simulated in 2018 (fig. 94). 

Simulated water levels in Devils Hole would have declined 

2 ft between 2018 and 2100, or 4 ft from predevelopment 

conditions, in the steady-pumping scenario had an alternative 

long-term natural fluctuation with a rise of 1.5 ft between 1973 

and 2017 been used.

Natural discharges are projected to increase by 1,600 

acre-ft/yr in Pahrump Valley and decrease slightly or not 

change in all other discharge areas between 2018 and 2100 

if pumping remains at 2010 rates in the steady-pumping 

scenario (table 13). Increased discharges were simulated in 

Manse Spring and are a response to locally rising water levels 

(fig. 51) that are projected to continue. Simulated discharges 

in Chicago Valley decreased by 10 acre-ft/yr between 2018 

and 2100, whereas simulated discharges in the Shoshone 

and Tecopa/California Valley areas are projected to remain 

unchanged from 2018 to 2100. Simulated discharges in the 

Ash Meadows and AFFCR groundwater basins decreased by 

about 1,000 acre-ft/yr between 2018 and 2100 (table 13).
Potential Effects of Future Groundwater Development 159

sac19-4233_fig 93

Effect of injection

Analytical model of long-term natural fluctuations

Year

−2

0

2

4

6

8

10

15

5

0

Groundwater withdrawals, 

in cubic feet per second

Groundwater withdrawals, 

in thousands of gallons

per minute

0

1

2

3

4

5

6

Depth below reference, in feet

1960 1970 1980 1990 2000

USGS 362532116172700 230 S17 E50 36DC 1 Devils Hole (AM-4)

Simulated predevelopment depth to water is 1.0 feet below reference

Injection in Devils Hole Well (AM-5)

Pumping by Cappaert Enterprises

Simulated with injection in Devils Hole Well (AM-5)

Simulated without injection in Devils Hole Well (AM-5)

Measured (includes natural fluctuations)

EXPLANATION

Figure 93. Groundwater withdrawals and injections (top graph); and measured 

water levels, and simulated water levels with and without injections (bottom graph), 

in Devils Hole Well (AM-5) (bottom graph), Nevada, 1960–2000.

Year

1950 2000 2050 2100

-4

-3

-2

-1

0

Water-level change from 

predevelopment conditions, in feet

DV3-AM-AFFCR, calibration model

DV3-PRED, all pumping ceases 2019

DV3-PRED, 2010 pumping continues

Measured without long-term natural fluctuations

EXPLANATION

Figure 94. Measured water levels without long-term natural fluctuations from recharge, and simulated water levels 

from DV3-AM-AFFCR and DV3-PRED models, in Devils Hole, Nevada, 1950–2100. DV3-AM-AFFCR, Death Valley version 3 

stress-response model simulating groundwater development in the Ash Meadows and Alkali Flat–Furnace Creek Ranch 

groundwater basins; DV3-PRED, Death Valley version 3 predictive model.
160 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Groundwater-Basin Boundary 

Uncertainty

Boundary uncertainty was addressed for all 

internal groundwater-basin boundaries in the study area. 

Predevelopment groundwater-flow paths, water-level declines 

from groundwater development, and hydraulic properties were 

used to determine whether groundwater-basin boundaries are 

barriers to flow.

The PMOV groundwater basin mostly is isolated from 

neighboring AFFCR and Ash Meadows groundwater basins. 

A net rate of 20 acre-ft/yr moves from the Ash Meadows 

groundwater basin into the PMOV groundwater basin 

(fig. 88). Limited flow occurs through the Belted Range 

along this boundary because of low-permeability rocks that 

form a barrier to flow (fig. 32). The southeastern boundary of 

the PMOV groundwater basin between Bare Mountain and 

Rainier Mesa is a good approximation of the groundwater 

divide (fig. 88). A small number of flow paths cross the 

southeastern PMOV boundary (fig. 80). However, the amount 

of simulated groundwater flow across this boundary is small 

(230 acre-ft/yr; fig. 88) and accounts for less than 4 percent 

of total discharge in Oasis Valley. Water-level declines from 

pumping in the PMOV groundwater basin also are isolated 

from declines associated with pumping centers in the AFFCR 

and Ash Meadows groundwater basins.

Low-permeability rocks (fig. 32) hydraulically isolate 

PDVS groundwater basin from the AFFCR and Ash Meadows 

groundwater basins (fig. 68). These low-permeability rocks 

cause pumping in Pahrump Valley to minimally affect 

water levels in Ash Meadows and AFFCR groundwater 

basins (fig. 57) because hydraulic connections to PDVS 

groundwater basin are limited to two locations of saturated 

basin fill. Saturated basin fill beneath the Amargosa River near 

Eagle Mountain connects AFFCR and PDVS groundwater 

basins (fig. 32), where simulated interbasin flow is about 60 

acre-ft/ yr (fig. 88). Saturated basin fill between Stewart Valley 

and the Ash Meadows discharge area connects PDVS and 

Ash Meadows groundwater basins (fig. 32), where simulated 

interbasin flow is about 180 acre-ft/yr (fig. 88).

Ash Meadows and AFFCR groundwater basins are 

coupled and are better considered as a single groundwater 

basin. The basin boundary extending from the well AD-4

corridor northward to Jackass Flats is a groundwater divide 

that was delineated based on water-level altitudes in wells 

(Fenelon and others, 2016). Areally extensive drawdowns 

from pumping in both groundwater basins have coalesced 

into a 2,200 mi2

 area (fig. 57), where these drawdowns 

have propagated across this boundary. Hydraulic continuity 

principally occurs through the well AD-4 corridor, where 

predevelopment groundwater flow is about 2,550 acre-ft/yr 

(fig. 88).

Boundary uncertainty was not addressed for external 

groundwater-basin boundaries, which bound the study area. 

External groundwater-basin boundaries were simulated as 

no-flow boundaries in the integrated DV3 model because the 

study area primarily is isolated from surrounding groundwater 

basins by low-permeability rocks and groundwater divides 

(Fenelon and others, 2016). Potential groundwater flow is 

expected to be limited from north of Kawich, Emigrant, 

Tikaboo, and Pahranagat Valleys (Winograd and Thordarson, 

1975; Harrill and others, 1988; Heilweil and Brooks, 2011; 

Fenelon and others, 2016). Potential groundwater flow across 

external boundaries was not precluded by no-flow boundaries 

because potential lateral flow was accommodated in simulated 

recharge estimates. Differentiating recharge from lateral flow 

along the study-area boundary was not possible because little 

data exist.

Evaluation of Advective Flow from 

Corrective Action Units

Advective-flow distances (and velocities) from 

underground nuclear tests are used to evaluate flow rates and 

boundary conditions in the (regional) DV3 model. Flow rates 

and boundary conditions from the DV3 model need to be 

evaluated because they support local-scale CAU models of 

groundwater flow and radionuclide transport. Flow rates and 

boundary conditions extracted from the DV3 model and used 

in a local-scale model highly influence the Darcy velocities 

of the local-scale model, which affect advective transport 

calculations. Evaluating advective movement along flow paths 

is a relevant way to determine the reasonableness of simulated 

flow rates near nuclear tests in the DV3 model.

Groundwater-flow paths were simulated from all 

underground nuclear tests detonated near or below the water 

table at the NNSS using the DV3-SS model. Advective-flow 

distances and velocities were computed along flow paths using 

the DV3-SS model. Computing advective velocities along 

simulated flow paths is a straight-forward calculation that 

requires an estimated effective porosity of the rocks along the 

flow path and hydraulic-conductivity and hydraulic-gradient 

values derived from the calibrated model. The advective 

velocity was used to calculate the distance a water particle 

would move in 165 years, which is the time necessary for 

tritium in a nuclear test cavity to decay to below the Safe 

Water Drinking Act (SDWA) standard of 20,000 pCi/L (U.S. 

Environmental Protection Agency, 2017), assuming an initial 

concentration of 2.2 × 108

 pCi/L (Pawloski and others, 2001). 

An advective-flow distance based on tritium decay is used 

because tritium is a conservative radionuclide. Computed 

165-year advective-flow distances are qualitatively compared 

to tritium data from wells downgradient from nuclear tests 

to ensure that the computed distances are consistent with 

known transport distances. Because the DV3-SS model was 

not calibrated to measured tritium concentrations, simulated 

groundwater-flow paths from nuclear tests are not expected to 

coincide with exact pathways of known tritium plumes.
Evaluation of Advective Flow from Corrective Action Units 161

Predevelopment groundwater-flow paths were not 

simulated for all 828 underground nuclear tests on the 

NNSS (U.S. Department of Energy, 2015). Flow paths were 

simulated only for the 296 underground nuclear tests (fig. 95) 

that were detonated below the water table or less than 328 ft 

(100 m) above the water table (Stoller-Navarro Joint Venture, 

2004b, 2005b; Navarro-Intera, LLC, 2013; U.S. Department 

of Energy, 2018). These 296 tests are considered to have the 

potential to introduce radionuclides directly into the saturated 

zone (Finnegan and others, 2016). Flow paths originated from 

model layer 1 for nuclear tests detonated above the water 

table, whereas flow paths originated in model layer 2, 3, 4 or 

5 for nuclear tests detonated below the water table. Model 

layer selection for each nuclear test detonated in the saturated 

zone was based on detonation depth below the simulated 

water table. Vertical locations of nuclear tests were checked 

to ensure that they intersected the correct hydrogeologic unit 

in the DV3 model. Flow paths were simulated by assigning an 

effective porosity of 0.01 to fractured volcanic and carbonate 

rocks, and an effective porosity of 0.1 to basin fill and 

volcanic-sedimentary rocks, which include the volcanic tuffs 

in Yucca Flat, Frenchman Flat, and Rainier Mesa.

The 165-year period used to calculate advective-flow 

distances along simulated flow paths from 296 underground 

nuclear tests was based on estimated initial tritium 

concentrations in nuclear-test cavities and the decay (half-life) 

coefficient for tritium of 12.3 years (Lucas and Unterweger, 

2000). Initial tritium concentration, in picocuries per liter, was 

estimated for each nuclear test using methods described in 

Stoller-Navarro Joint Venture (2005b) for tests in Frenchman 

Flat CAU, Stoller-Navarro Joint Venture (2004b) for tests 

in Pahute Mesa CAU, Navarro-Intera, LLC (2013) for tests 

in Yucca Flat–Climax Mine CAU, and U.S. Department of 

Energy (2018b) for tests in Rainier Mesa–Shoshone Mountain 

CAU. Initial concentrations ranged from 1.5 × 104

 to 2.2 × 108

pCi/L and averaged 8.5 × 107 pCi/L. For each nuclear test, 

the elapsed time was computed for tritium to radioactively 

decay from the initial concentration to the SDWA standard of 

20,000 pCi/L (U.S. Environmental Protection Agency, 2017). 

The elapsed time ranged from 7 to 165 years and averaged 

120 years. The upper bound of elapsed time was used to 

calculate the distance traveled from each test, which resulted 

in calculated distances for tests with low initial concentrations 

to be overestimated.

The 165-year advective-flow distances from each 

nuclear-test location are shown in figure 95. Advective-flow 

distances less than 400 ft are not shown on the figure because 

distances are too short to easily discern. Calculated advectiveflow distances may be greater than actual tritium migration 

distances because the calculated distances do not account for 

dispersive effects. For example, not accounting for dispersion 

and matrix diffusion will overestimate downgradient migration 

distances. Because of potential for overestimation from using 

the upper bound of elapsed time and not accounting for 

dispersive effects, calculated advective-flow distances likely 

are biased high relative to the maximum extents of tritium 

transport above the SDWA standard.

Calculated 165-year advective-flow distances from 

underground nuclear tests are consistent with tritium 

migration distances, as determined from well samples and 

from radionuclide transport studies in Frenchman Flat, Yucca 

Flat–Climax Mine, and Rainier Mesa–Shoshone Mountain 

CAUs. Calculated advective-flow distances extend less than 

0.5 mi from all underground nuclear tests in these CAUs, 

which is consistent with actual tritium migration distances 

between nuclear-test cavities and sampled wells. Tritium at 

concentrations greater than SDWA standards (20,000 pCi/L) 

has been measured only in wells within 300 ft of nuclear 

tests and in post-shot holes drilled into nuclear-test cavities 

or chimneys in Frenchman Flat and Yucca Flat–Climax 

Mine CAUs (Smith, 2002)3

. In the Rainier Mesa–Shoshone 

Mountain CAU, tritium at concentrations greater than SDWA 

standards has been measured only in water from flooded 

tunnels where the tests were detonated (U.S. Department 

of Energy, 2018). Measured tritium migration distances are 

expected to be shorter than calculated 165-year advectiveflow distances because only 25–60 years have elapsed 

from present (2018) since nuclear tests were detonated in 

these CAUs. Detailed, smaller-scale, model analyses, using 

conservative assumptions, have been published that support 

limited downgradient migration from Frenchman Flat, Yucca 

Flat–Climax Mine, and Rainier Mesa–Shoshone Mountain 

CAUs. Simulated tritium at concentrations greater than SDWA 

standards remained within NNSS boundaries over a 1,000-

year period for underground nuclear tests in Frenchman Flat 

(Navarro Nevada Environmental Services, LLC, 2010), Yucca 

Flat–Climax Mine (Navarro-Intera, LLC, 2013), and Rainier 

Mesa–Shoshone Mountain CAUs (U.S. Department of Energy, 

2018). These simulated results are consistent with computed 

advective-flow distances from this study.

Pahute Mesa has known tritium plumes migrating from 

BENHAM/TYBO (Wolfsberg and others, 2002), CHESHIRE 

(Pawloski and others, 2001), and HANDLEY (Navarro-Intera, 

LLC, 2015) nuclear tests. The longest measured plumes to 

date (2018) occur downgradient of the BENHAM/TYBO and 

HANDLEY tests. Tritium at concentrations greater than the 

SDWA standard has moved at least 2.6 mi in 50 years from 

the BENHAM/TYBO test and 1.9 mi in 48 years from the 

HANDLEY test (Mission Support and Test Services, LLC, 

2018). Tritium data indicate that advective transport velocities 

range from at least 205 ft/yr from the HANDLEY test to 276 

ft/yr from the BENHAM/TYBO test. Assuming uniform 

advective transport velocities along flow paths from these 

nuclear tests and initial tritium concentrations of 2.2 × 108

pCi/L, maximum tritium migration at concentrations greater 

than the SWDA standard ranges from 6.4 to 8.6 mi from 

HANDLEY and BENHAM/TYBO tests, respectively.

3

 Tritium concentrations greater than the SDWA standard only were 

considered from sites where tritium migrated from the source in the 

groundwater system through either predevelopment flow or induced flow from 

pumping. Well UE-5n in Frenchman Flat was not included because tritiated 

groundwater withdrawn from well RNM-2S was discharged into an unlined 

ditch, infiltrated basin fill beneath the ditch, and contaminated groundwater in 

the vicinity of well UE-5n (Smith, 2002).
162 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

sac19-4233_fig 95

190

95

95

373

Mercury

Amargosa

Valley

Beatty

Furnace

Creek

CALIFORNIA

NEVADA

LINCOLN CLARK

NYE

INYO

ASH MEADOWS

PAHUTE MESA–

OASIS VALLEY

ALKALI FLAT–

FURNACE

CREEK

RANCH

Yucca

Flat

Rainier 

Mesa

BULLFROG

HILLS

Pahute Mesa

Oasis Valley

Belted Range

Gold Flat Kawich Valley

Timber Mountain

Yucca Mountain

Jackass Flats

Funeral Mountains

Amargosa Desert

Frenchman Flat

Specter Range

Halfpint Range

Eleana Range

Bare Mountain

Quartzite

Ridge

CP 

Basin

Climax Mine

Shoshone 

Mountain

Frenchman 

Flat CAU

Yucca Flat – 

Climax Mine 

CAU

Rainier Mesa–

Shoshone Mountain 

CAU

Pahute Mesa 

CAU

Devils Hole 

0 10 MILES

0 5

5

10 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000. Hillshade from U.S. Geological Survey 1-arc second 

National Elevation Universal Transverse Mercator Projection, Zone 11, North American Datum of 1983.

116°30' 116°

37°

36°

30'

EXPLANATION

Groundwater basin boundary 

modified from Fenelon and 

others (2016)

Nevada National Security 

Site boundary and internal 

operations areas

Corrective Action Unit (CAU) 

—From U.S. Department 

of Energy (2018a)

Advective flow path from 

 underground nuclear test 

—Path is distance traveled 

in 165 years from date of 

nuclear-test detonation. 

Paths less than 400 feet not 

shown.

Underground nuclear test 

—Tests detonated below 

the water table or less 

than 328 feet (100 meters) 

above water table.

Observation site

Map

area

Study 

area

Figure 95. Simulated 165-year advective-flow paths from 296 underground nuclear tests detonated near or below the 

water table, in the study area, Nevada National Security Site, Nevada. Simulated flow paths do not coincide with tritium 

plumes and do not represent tritium plumes.
Model Limitations 163

Calculated 165-year advective-flow distances from 

underground nuclear tests are consistent with downgradient 

extents of measured tritium plumes in the Pahute Mesa 

CAU. Advective-flow distances from nuclear tests range 

from less than 0.1 to 12.6 mi and average 1.8 mi. Advective 

velocities range from 0.03 to 400 ft/yr and average 60 ft/yr. 

These calculated advective-flow distances and velocities are 

within the range of estimated tritium migration distances from 

HANDLEY and BENHAM/TYBO tests.

Simulated groundwater-flow paths do not coincide with 

known tritium plumes in the Pahute Mesa CAU. Discrepancies 

are attributed to DV3-SS model limitations. Computed 

advective-flow distances from HANDLEY and BENHAM/

TYBO tests are shorter than measured transport distances 

because advective velocities in the DV3 model are controlled 

by low (less than 50 ft2/d) transmissivities in wells near these 

tests and the DV3-SS model was not calibrated to tritium 

concentrations in downgradient wells. Despite these model 

errors, computed advective-flow distances for all tests suggest 

that a limited number of plumes with tritium concentrations 

greater than SDWA standards exist and that these plumes will 

migrate only a few miles. This is consistent with the number 

and migration distance of identified tritium plumes on Pahute 

Mesa. Furthermore, although simulated flow paths locally 

do not match observed tritium plumes, simulated flow paths 

from all tests end in Oasis Valley, which is consistent with the 

expected discharge location (Fenelon and others, 2010, 2016).

Boundary conditions and flow rates from the DV3 model 

can be applied to local-scale CAU transport models, where 

tritium transport migration results can be refined. Advectiveflow distances in Frenchman Flat, Yucca Flat–Climax Mine, 

and Rainier Mesa–Shoshone Mountain CAUs are consistent 

with expected tritium transport distances based on data and 

previous numerical studies. Advective velocities from nuclear 

tests in Pahute Mesa CAU are within the range of actual 

tritium migration velocities from HANDLEY and BENHAM/

TYBO tests. Similarities between measured transport 

velocities and calculated advective velocities indicate that flow 

rates in the DV3 model are reasonable.

A steady-state assumption is appropriate for simulation 

of flow and transport within CAU-scale models. Advectiveflow distances from underground nuclear tests in Frenchman 

Flat, Yucca Flat–Climax Mine, and Rainier Mesa–Shoshone 

Mountain CAUs are less than 0.5 mi. These flow paths do 

not extend into shallow carbonate rocks of the regional 

carbonate aquifer and, therefore, effects of regional pumping 

on advective transport are negligible. Advective-flow distances 

are more than 5 mi from several nuclear tests in the Pahute 

Mesa CAU. However, the PMOV groundwater basin is 

a hydraulically isolated basin. Water-level declines from 

pumping in AFFCR and Ash Meadows groundwater basins 

do not extend into the PMOV groundwater basin (fig. 57). 

Pumping within the PMOV groundwater basin has withdrawn 

about 26,000 acre-ft of groundwater from storage between 

1945 and 2010 (fig. 89), which has affected water levels only 

locally (Jackson and Fenelon, 2018).

Model Limitations

The DV3 model addresses questions about 

predevelopment groundwater flow, groundwater development, 

and advective-flow rates in the study area. Veracity of 

simulated results depends on how well the DV3 model 

approximates the actual system. Simplification of underlying 

conceptual models, uncertainty in estimates of predevelopment 

groundwater discharges, and errors in pumping estimates are 

major limitations. These limitations result from insufficient 

measurements to fully account for variations in hydraulic 

properties and stresses throughout the model area. Spatial and 

temporal discretization also affect results, but these numerical 

limitations are minor relative to data limitations.

Groundwater discharges substantially affect numerical 

model results but remain poorly defined from Furnace Creek 

and Lower Amargosa discharge areas. Predevelopment 

groundwater discharge from the Furnace Creek area totals 

8.5 ft3/s (6,100 acre-ft/yr) in this investigation, but likely 

is overestimated. Measured discharges from springs and 

diversions were not concurrent and discharge from the 

alluvial fan below Furnace Creek Wash was estimated with 

extrapolated ETGW rates. Average simulated transmissivities of 

30,000 ft2/d through Furnace Creek Wash are biased high and 

suggest that discharge from the alluvial fan was overestimated. 

Groundwater discharge from the Lower Amargosa area 

was estimated exclusively with extrapolated ETGW rates. 

Uncertainty of groundwater discharge from the Furnace Creek 

and Lower Amargosa areas can be reduced by appropriate 

investigations.

Simulated effects of pumping from the central Amargosa 

Desert on water levels in Devils Hole depend greatly on the 

well AD-4 corridor. Water-level profiles confirm the existence 

of the well AD-4 corridor, but the degree of hydraulic 

connection has not been estimated independently. Pumping 

from carbonate rocks east of well AD-4 and observing 

drawdowns in basin fill around well AD-4 would confirm the 

magnitude of hydraulic connection through the well AD-4

corridor.

The area north and east of the NNSS remains poorly 

defined because less than 24 wells were available (fig. 46). 

This 3,300 mi2

 area encompasses Gold Flat in the northwest, 

the Pahranagat Range in the northeast, and the Sheep Range 

in the southeast, and covers 30 percent of the study area. 

Estimated hydraulic properties of carbonate rocks east and 

north of well USAF R65N (fig. 49) mostly were uninformed 

by data. Hydraulic properties of basin fill and carbonate rocks 

between well Army 1 WW and Indian Springs were minimally 

informed by water levels (figs. 29 and 46) and aquifer-test 

results (fig. 19).
164 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Measured groundwater levels and discharges were not 

matched perfectly by their simulated equivalents, even after 

calibration, because errors cumulatively affect model results. 

These irreducible errors result from simplification of the 

conceptual model, grid scale, and insufficient measurements. 

Simulated and measured quantities should be compared to 

estimate uncertainty of specific simulated results. Plausibility 

of predicted drawdowns in a well should be evaluated by 

similarity between simulated and measured water-level 

changes prior to prediction. For example, simulated water 

levels in ET areas within Chicago Valley and near Tecopa 

(fig. 55) show spatial biases because there is a structural 

model error that cannot be resolved with the limited data 

available. Clayey Tecopa Lake beds and underlying China 

Ranch beds remain undifferentiated in the hydrogeologic 

framework. This conceptual model was not incorporated 

because differences cannot be defined without wells and well 

logs. The structural model error does not affect the timing of 

capture between Pahrump and Shoshone because drawdowns 

in well Hwy 127 MM21-1 provide information about the 

hydraulic connection between these areas (fig. 57). However, 

data are unavailable to provide information about the timing 

and magnitude of drawdown and capture near Tecopa from 

pumping in Pahrump.

Simulation results indicate that about 180 acre-ft/

yr of groundwater moves northward from Pahrump Valley 

to the Ash Meadows discharge area (fig. 88). This result is 

speculative and uncertain because of a lack of water-level data 

in wells to constrain flow between Pahrump Valley and the 

Ash Meadows discharge area. For example, measured water 

levels in well GS-1 Well (AD-12) (fig. 6) have declined about 

0.5 ft since 1996. The DV3-PDVS model simulated less than 

0.1 ft of water-level decline from 1913 to 2018 in response 

to pumping from Pahrump Valley. Most of the water-level 

decline in well GS-1 Well (AD-12) may be attributed to poor 

well construction or slow water-level equilibration following 

well construction (Fenelon and Moreo, 2002). Well GS-1 

Well (AD-12) is a recompleted borehole that initially was 

drilled for mineral exploration. The USGS cased the existing 

borehole in 1986, where monitoring well GS-1 Well (AD-12)

is a 10-ft interval at the bottom of the borehole open to lowpermeability calcareous mudstone (Fenelon and Moreo, 2002). 

Slow water-level recovery following well completion likely 

explains most of the water-level decline in this well.

Lateral discretization of the study area into a rectangular 

grid of cells and vertical discretization into layers forced an 

averaging of hydraulic properties. Each cell was assumed to 

represent a homogeneous block or some volumetric average 

of the aquifer medium. Discretization errors occurred in every 

model cell, which includes the smallest model cells. Bedding 

structures in the alluvium and fracture networks in the bedrock 

were averaged even in the smallest cells, which were 820 ft on 

a side and 160 ft thick. Flow paths were averaged over lengths 

of about 0.3 mi because hydraulic properties are averaged.

Errors in hydraulic diffusivity inversely affect the timing 

of groundwater capture. Hydraulic diffusivity is transmissivity 

divided by storativity, which functionally is specific yield for 

unconfined aquifer conditions. Groundwater capture will occur 

sooner as hydraulic diffusivity increases and will be delayed as 

hydraulic diffusivity decreases. Errors in hydraulic-diffusivity 

estimates of 50 percent in the DV3-PRED model are not 

unexpected, so 50-percent errors in timing of groundwatercapture estimates can occur.

The spatial distribution of simulated recharge minimally 

affects model results. Simulated recharge refines hydraulicconductivity estimates; however, most recharge occurs 

upgradient of areas of interest. For example, hydraulicdiffusivity estimates in the Furnace Creek area, central 

Amargosa Desert, megachannel, and Pahrump Valley 

primarily were defined by fitting to measured water-level 

declines from pumping and water-level altitudes from 

predevelopment discharges. In these areas where hydraulicdiffusivity estimates affect predictions of pumping on water 

levels, the effect of upgradient recharge is minimal. The 

total volume of recharge is more important. For example, in 

Pahute Mesa, the total volume of recharge is well defined 

because total discharge in Oasis Valley is defined well from 

detailed micrometeorological measurements (Laczniak 

and others, 1999; Reiner and others, 2002). The simulated 

recharge distribution may be nonunique, but most recharge 

occurs upgradient of nuclear tests that define the leading 

edge of transport from Pahute Mesa. Total subsurface flow 

downgradient of Pahute Mesa should be simulated correctly, 

and this flow is constrained by ensuring a water balance 

between recharge and discharge in the PMOV groundwater 

basin. The spatial recharge distribution is most important for 

Rainier Mesa; however, total recharge is limited by lowpermeability volcanic rocks (tunnel beds).

Changes in recharge in response to climate change were 

not considered in this study. The steady-state (DV3-SS) model 

assumes recharge remains unchanged over a timescale of more 

than a century. Water-level changes from changes in recharge 

are assumed small, such that transmissivity is not a function 

of thickness. Therefore, changes in recharge do not affect the 

hydraulic properties of the groundwater system. Groundwater 

development (DV3-AM-AFFCR and DV3-PDVS) models 

and the predictive (DV3-PRED) model do not simulate timevarying changes in recharge and temporal recharge trends 

were removed from well hydrographs, where appropriate. 

If future recharge decreases within the next 100 years, then 

drawdowns will increase. The DV3-AM-AFFCR, DV3-PDVS, 

and DV3-PRED models simulate water-level declines from 

pumping only. The estimation of spatially distributed waterlevel changes from historical variations in recharge and likely 

future changes were beyond the scope of this study.
Summary 165

Summary

The study area consists of the Pahute Mesa–Oasis Valley 

(PMOV), Alkali Flat–Furnace Creek Ranch (AFFCR), Ash 

Meadows, and Pahrump to Death Valley South (PDVS) 

groundwater basins in Nevada and California. Radionuclides 

were introduced into the groundwater system of the study area 

by underground nuclear testing beneath the Nevada National 

Security Site (NNSS). Pumping by Cappaert Enterprises 

in the Ash Meadows discharge area during the 1970s 

directly affected water levels in Devils Hole, the exclusive 

habitat of the endangered Devils Hole pupfish, Cyprinodon 

diabolis. Pumping for irrigation in the central Amargosa 

Desert and Pahrump Valley can adversely affect federally 

protected groundwater-dependent ecosystems. Groundwaterbasin boundaries were uncertain, which affects potential 

radionuclide migration directions and the degree of hydraulic 

connection between pumping centers and groundwaterdependent ecosystems.

To address the above stated problems, the five purposes 

of this report were to:

1. Characterize predevelopment groundwater flow;

2. Evaluate effects of historical (1913–2018) groundwater 

development on water levels and discharges;

3. Estimate potential future (2019–2100) effects of 

groundwater development on water levels and spring 

discharges;

4. Evaluate advective flow from selected underground 

nuclear tests to determine if boundary conditions and 

flow rates from the regional model in this study are 

reasonable for local-scale flow and transport models; and

5. Address groundwater-basin boundary uncertainty in the 

study area.

Characterization of predevelopment groundwater flow 

required conceptual models for recharge, discharge, and 

hydraulic-conductivity distributions within hydrogeologic 

units. Conceptual models integrated water-level data, 

transmissivity estimates, geologic data, water availability in 

recharge areas, and locations and estimates of predevelopment 

discharge. A hydrogeologic framework was used to distribute 

hydraulic properties within hydrogeologic units during 

simulation of predevelopment and groundwater development.

Regional discharge areas were analyzed critically 

because hydraulic-property estimates and predictions of 

groundwater capture depend greatly on specified locations 

and rates of discharges. Virtually all discharge from the Ash 

Meadows discharge area was attributed directly to springs. 

The predevelopment water budget from the Furnace Creek 

area included diversions from Furnace Creek Wash, a major 

hydrologic feature that conveys groundwater to the alluvial 

fan at Furnace Creek. Discharges from Pahrump and Stewart 

Valleys likely totaled 13,300 acre-feet per year (acre-ft/

yr) prior to development, with 9,800 acre-ft/yr (13.5 cubic 

feet per second) discharging from Bennetts and Manse

Springs. Discharge from the Lower Amargosa area ceased 2 

miles south of Tecopa, where China Ranch beds above the 

Amargosa River were eroded or unsaturated. Saratoga Spring 

area is supplied primarily by base flow in the Amargosa River 

that infiltrates basin fill below Dumont Dunes. Playas were 

interpreted as low-permeability features that discharged very 

little groundwater.

Relations between transmissivity, rock type, and depth in 

the study area were investigated with transmissivity estimates 

from 271 aquifer tests and specific capacities. Rocks were 

categorized into four hydraulically distinct hydrogeologic 

units: (1) basin fill; (2) carbonate rocks; (3) volcanic rocks; 

and (4) low-permeability granitic and siliciclastic rocks. 

Thicknesses of hydrogeologic units and their transmissivities 

were not correlated regardless of rock type. More than 90 

percent of estimated transmissivity in carbonate and volcanic 

rocks occurred within 1,600 feet (ft) of the water table. 

Contributing intervals composed less than 10 percent of 

open holes in carbonate and volcanic rocks and did not occur 

predictably with depth.

A hydrogeologic framework was developed with 

simplified hydrogeologic units that were appropriate for 

extrapolating hydraulic conductivities. The hydrogeologic 

framework was divided into five layers and extended from the 

water table to 3,300 ft below the National Geodetic Vertical 

Datum of 1929 (NGVD29). Thick sequences of carbonate 

and volcanic rocks were divided into shallow and deep 

intervals based on analysis of hydraulic conductivity with 

depth. Hydrogeologic interpretations from the Underground 

Test Area project were incorporated in the framework 

because drilling 34 new boreholes and completing 119 new 

wells during 2000–2016 reduced geologic and hydrologic 

uncertainties. Major hydrologic features, such as Furnace 

Creek Wash and China Ranch beds, were incorporated 

explicitly in the hydrogeologic framework. 

Pumping in the study area averaged 46,000 

acre-ft/yr from 1960–2010 and totaled 38,000 acre-ft/yr in 

2010. The 46,000 acre-ft/yr of pumping averaged 80 percent 

of the predevelopment discharge, which totaled about 55,000 

acre-ft/yr. Annual pumping in the PDVS groundwater basin 

peaked at 46,000 acre-ft/yr in 1968 and exceeded the basin 

predevelopment discharge of 22,400 acre-ft/yr between 

1955 and 2000. Pumping from AFFCR and Ash Meadows 

groundwater basins gradually increased from 700 

acre-ft/yr in 1950 to 21,000 acre-ft/yr in 2010 and has not 

exceeded the predevelopment discharge of 26,000 

acre-ft/yr. Pumping by Cappaert Enterprises in the Ash 

Meadows discharge area totaled 42,000 acre-ft during 1969–

1977. Water levels declined 2.3 ft in Devils Hole in response 

to this pumping. Return flows from irrigation, domestic, and 

metered pumping in the study area averaged 20 percent of 

the pumping, with a 2-year delay between application and 

recharge to the water table.
166 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

The central Amargosa Desert and Pahrump Valley were 

the two primary pumping centers and affected water levels 

in areas of 300 and 600 square miles (mi2

), respectively. 

These broad areas were delineated using dozens of wells, 

where water levels declined at rates greater than 0.1 ft per 

decade. Delineation of areas affected by pumping were more 

tenuous in the Funeral Mountains and Lower Amargosa 

area because observation wells were few or non-existent 

there. Groundwater levels distant from pumping centers rose 

between 1980 and 2018 throughout most of the study area in 

response to a wetter-than-average period from 1970 to 2018.

Water-level changes in Devils Hole have been influenced 

measurably by long-term natural fluctuations in addition to 

pumping. These long-term natural fluctuations appear as 

multiple-decade periods of declining or rising water levels 

and result from differences between episodic recharge and 

steady discharge. Water levels in Devils Hole were simulated 

with an analytical water-level model so that long-term, 

natural fluctuations from recharge could be estimated and 

differentiated from pumping effects. Estimated long-term, 

natural fluctuations suggest that water levels in Devils Hole

would have risen about 1 ft between 1973 and 2018 in the 

absence of pumping.

Recharge and hydraulic-property distributions in the 

study area were estimated by simultaneously calibrating four 

numerical, groundwater models. Predevelopment (steadystate) conditions (DV3-SS model); groundwater development 

in Ash Meadows, AFFCR, and PMOV groundwater basins 

(DV3-AM-AFFCR model); groundwater development in 

PDVS groundwater basin (DV3-PDVS model); and the 

well ER-6-1-2 main multiple-well aquifer test (DV3-ER612 

model) were simulated with four stress-response models. 

Stress-response pairs were isolated with separate models so 

that fewer errors were introduced compared to simulating 

all responses with a single generalized model. For example, 

discharge rates were specified at nearly all springs and 

evapotranspiration areas in the DV3-SS model, whereas 

discharge was simulated using capture-limited boundaries in 

DV3-AM-AFFCR, DV3-PDVS, and DV3-ER612 models, 

which prevented simulated captures from exceeding measured 

discharges.

Hydraulic-conductivity, specific-yield, specific-storage, 

and recharge distributions, as well as extinction depths from 

springs with known captures were estimated by minimizing 

a weighted composite, sum-of-squares objective function 

that included measurement and Tikhonov regularization 

observations. Measured observations included waterlevel altitudes, water-level differences between wells, 

transmissivities, selected flow rates, temporal water-level 

changes, and spring captures. Simulated responses from 

all four groundwater models were compared to measured 

observations and the comparisons simultaneously informed 

revised parameter estimates. Hydraulic conductivity, specific 

yield, specific storage, and recharge were distributed with 

pilot points in the groundwater models so that observed 

spatial variability could be simulated in hydrogeologic 

units. Simulated responses compare favorably to measured 

observations for all quantifiable observations.

Simulated water-level changes in Devils Hole were the 

summation of pumping changes that were simulated with the 

DV3-AM-AFFCR model and long-term, natural fluctuations 

from episodic recharge and steady discharge that were 

simulated with an analytical water-level model. Measured 

and simulated (numerical + analytical model) water levels 

in Devils Hole agreed with a root-mean-square error of 0.2 

ft. Overall shape of water levels and responses to pumping 

stresses in Devils Hole agreed through the nearly 70-year 

period of record.

Eight major hydrologic features were identified in the 

study area and were simulated correctly:

1. The perched water-table mound beneath Rainier Mesa, 

which allows for numerical simulation of groundwater 

flow from nuclear tests in Rainier Mesa.

2. The boundary between PMOV and AFFCR groundwater 

basins, which affects rates and directions of radionuclide 

migration from Pahute Mesa.

3. The megachannel—a high hydraulic diffusivity feature 

that causes drawdowns to propagate quickly and 

recover slowly. The megachannel extends from Ash 

Meadows discharge area to Indian Springs and from the 

southernmost part of the NNSS to northern Yucca Flat. 

4. The Gravity fault, which forms a flow barrier that 

juxtaposes low-permeability basin fill downgradient of 

highly transmissive carbonate rocks. The Gravity fault 

causes groundwater to move upward and discharge from 

springs in the Ash Meadows discharge area.

5. The well AD-4 corridor, which hydraulically connects 

Ash Meadows and AFFCR groundwater basins.

6. Alluvial deposits along Furnace Creek Wash, which 

transmit groundwater above Travertine Springs to the 

alluvial fan on the floor of Death Valley.

7. Black Mountains and Greenwater Range forming flow 

barriers, which isolate Death Valley from the central 

Amargosa Desert and Amargosa River.

8. Carbonate rocks and basin fill forming a continuous 

aquifer between the Spring Mountains and the Amargosa 

River.

Predevelopment (DV3-SS model) results indicate that 

the recharge source or sources for most of the major discharge 

areas are derived from the same groundwater basin. Oasis 

Valley, Ash Meadows discharge area, Bennetts and Manse

Springs, and Lower Amargosa area primarily discharge 

groundwater that was recharged in the same groundwater 

basin. Discharge from the Furnace Creek area was atypical 

because more than 40 percent of the discharge was recharged 

in another groundwater basin.
Summary 167

The well AD-4 corridor is an area of considerable 

interbasin flow (2,550 acre-ft/yr) that hydraulically connects 

AFFCR and Ash Meadows groundwater basins. The longest 

flow paths in the study area pass through the well AD-4

corridor. Groundwater flows upward from carbonate rocks 

in Ash Meadows groundwater basin to basin fill in the well 

AD-4 corridor, moves west through the central Amargosa 

Desert, flows from basin fill to carbonate rocks in the Funeral 

Mountains, and continues to flow westward to the Furnace 

Creek area before discharging. This flow path is consistent 

with hydraulic and hydrochemical evidence. Results from the 

DV3-SS model also are consistent with this conceptual model 

of connecting recharge and discharge areas through basin fill 

in the central Amargosa Desert. An alternative conceptual 

model connects recharge and discharge areas through deep 

carbonate rocks along the Furnace Creek fault zone, but this 

conceptual model is less probable based on hydraulic and 

hydrochemical data.

Water budgets were simulated for subareas of 

groundwater basins in the study area to estimate groundwaterflow rates from corrective action units (CAUs) at the NNSS 

and to inform water availability in subareas. More than 90 

percent of the groundwater discharging in Oasis Valley is 

derived from recharge sourced at Pahute Mesa and Timber 

Mountain. About 80 percent (17,400 acre-ft/yr) of recharge 

in Ash Meadows groundwater basin is derived from the 

Spring Mountains and Sheep Range. Less than 3 percent of 

the predevelopment flow in Ash Meadows groundwater basin 

moves through Yucca Flat. Slightly more than one-half (2,840 

acre-ft/yr) of the recharge in AFFCR groundwater basin is 

derived from Timber, Yucca, and Shoshone Mountains. Most 

groundwater that enters the Amargosa Desert moves westward 

toward Furnace Creek. Total simulated discharge at Franklin 

Lake is 440 acre-ft/yr, with most of this discharge sourced 

from the Amargosa Desert. Most recharge to the PDVS 

groundwater basin occurs in the Spring Mountains.

Ash Meadows and AFFCR groundwater basins are 

coupled and are better considered as a single groundwater 

basin. Areally extensive drawdowns from pumping in both 

groundwater basins have coalesced into a 2,200-mi2 area. 

Hydraulic continuity principally occurs through the well AD-4

corridor. The PDVS groundwater basin functionally is limited 

to transmissive rocks between the Lower Amargosa area and 

the Spring Mountains and is hydraulically isolated from other 

groundwater basins in the study area. The PMOV groundwater 

basin also is hydraulically isolated from other basins and the 

DV3 model supports the previously mapped boundary.

Groundwater development in the study area principally 

has removed water from storage because most of the pumping 

has been relatively distant from discharge areas. Cumulative 

pumping volumes totaled 50, 31, and 19 percent from storage 

depletion, capture, and return flow, respectively, during 

groundwater development between 1910 and 2018. Sources 

differed considerably by groundwater basin. Storage depletion 

supplied greater than 90 percent of pumped water from 

AFFCR and Ash Meadows basins. Storage depletion annually 

exceeded capture during peak pumping between 1952 and 

1985 in the PDVS groundwater basin. Capture was substantial 

where groundwater development occurred near springs in 

Pahrump Valley and the Ash Meadows discharge area.

Only pumping centers in the central Amargosa Desert 

and Ash Meadows groundwater basin measurably affected 

water levels in Devils Hole. Pumping by Cappaert Enterprises 

and the NNSS inside the megachannel have most affected 

water levels in Devils Hole and accounted for 50 percent of 

the anthropogenic water-level decline in 2018. Water levels in 

Devils Hole have declined slowly and steadily from pumping 

in the central Amargosa Desert, which accounted for a third of 

the anthropogenic water-level decline in 2018.

Future depths to water below the reference in Devils 

Hole depend on pumping and long-term natural fluctuations. 

Water levels in Devils Hole likely will decline between 0.1 

and 0.2 ft per decade during the next 80 years, assuming future 

pumping rates are similar to 2010 rates. Analytically simulated 

natural fluctuations between 1900 and 2018 have ranged from 

declines of 0.1 ft per decade to rises of 0.3 ft per decade. 

Natural fluctuations depend on future precipitation and are 

functionally unknown, but likely will be bound by historical 

rates of change for the next few decades.

Advective-flow distances and velocities from 

underground nuclear tests in the DV3 model are within the 

range of advective transport calculations from tritium data 

and previous radionuclide transport investigations. This result 

indicates that boundary conditions and flow rates from the 

(regional) DV3 model are reasonable for local-scale CAU 

transport models. Simulated 165-year groundwater-flow paths 

also do not extend into pumping areas and effects of regional 

pumping on advective transport are negligible. This result 

indicates that a steady-state (predevelopment) assumption is 

appropriate for local-scale CAU flow and transport models.

The DV3 model is a major improvement compared to 

previous regional models of the study area, such as the Death 

Valley Regional Flow System version 2 (DVRFS.v2) model. 

Veracity of simulated results depends on how well a model 

approximates the actual system. Compared to the DVRFS.

v2 model, the DV3 model has a better fit between measured 

and simulated water-level altitudes, water-level differences 

between wells, transmissivities, discharges, temporal waterlevel changes, and spring captures. The DV3 model also 

is consistent with conceptual models of predevelopment 

flow through groundwater-discharge areas and major 

hydrologic features, unlike the DVRFS.v2 model, which had 

inconsistencies between conceptual models and numerical 

results.

Results from the DV3 model can support future 

investigations of radionuclide transport and pumping effects 

in the study area. Boundary conditions and flow rates from 

the DV3 model can support boundary conditions applied to 

local-scale models of flow and radionuclide transport from 

the Pahute Mesa and Yucca Flat–Climax Mine CAUs. The 

DV3 model also can estimate potential effects of groundwater 

development on water levels in Devils Hole and other 

federally protected groundwater-dependent ecosystems in the 

study area.
168 Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California

Acknowledgments

The authors gratefully acknowledge John Klenke of 

the Nuclear Waste Repository Project Office in Nye County, 

Nevada, for providing Pahrump Valley and Amargosa Desert 

water-level data. The authors also gratefully acknowledge the 

following U.S. Geological Survey personnel:

• Steven R. Reiner and Peggy E. Elliott for data 

processing,

• Donald S. Sweetkind for providing geologic insights 

and technical guidance to revise the Death Valley 

version 3 (DV3) hydrogeologic framework,

• Nora Nelson for assisting with documentation of the 

model archive of the data release,

• Rebecca Frus for quality assurance and documentation 

of transmissivity estimates in Appendix B of the data 

release,

• Philip Gardner and Steve Van Denburgh for providing 

technical guidance in evaluation of water-chemistry 

data, and

• Joseph M. Fenelon for providing conceptual guidance 

of hydrologic principles developed in this report 

and for quality assurance of water-chemistry data in 

Appendix G of the data release.

The authors gratefully acknowledge the reviewers of this 

report, model archive, and data release appendixes for their 

helpful comments:

• Karl Pohlmann and Chuck Russell of the Desert 

Research Institute;

• Edward M. Kwicklis of Los Alamos National 

Laboratory;

• Peter Martian of Navarro, LLC;

• Richard Waddell and Guy Roemer of Tetra Tech;

• Sue Braumiller of the U.S. Fish and Wildlife Service;

• Paula A. Cutillo of the U.S. National Park Service; and

• Joseph M Fenelon, Philip Gardner, Leonard Konikow, 

and Stanley Leake of the U.S. Geological Survey. 

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Publishing support provided by the U.S. Geological Survey

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For more information concerning the research in this report, contact the

Director, Nevada Water Science Center

U.S. Geological Survey

2730 N. Deer Run Road

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Halford and Jackson—Groundwater Characterization and Effects in Death Valley Regional Groundwater Flow System, Nevada and California—Professional Paper 1863

ISSN 1044-9612 (print)

ISSN 2330-7102 (online)

https://doi.org/10.3133/pp1863