U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2018–5067

Prepared in cooperation with the Fort Irwin National Training Center

Geohydrology, Geochemistry, and Numerical Simulation 

of Groundwater Flow and Land Subsidence in the Bicycle 

Basin, Fort Irwin National Training Center, California

Bicycle

Basin

Bicycle

Lake

(dry)
Cover photographs:

Front cover: Aerial view of the Bicycle Basin and Bicycle Lake (dry) playa. (Photograph from Fort Irwin National Training Center, 2007)

Back cover: Bicycle Lake playa inundated following several winter storms. View looking east across the playa at Tiefort Mountain. (Photo taken on 

December 23, 2010, J.N. Densmore, U.S. Geolgical Survey.) 
Geohydrology, Geochemistry, and 

Numerical Simulation of Groundwater 

Flow and Land Subsidence in the Bicycle 

Basin, Fort Irwin National Training Center, 

California

By Jill N. Densmore, Linda R. Woolfenden, Diane L. Rewis, Peter M. Martin, 

Michelle Sneed, Kevin M. Ellett, Michael Solt, and David M. Miller

Prepared in cooperation with the Fort Irwin National Training Center

Scientific Investigations Report 2018–5067

U.S. Department of the Interior

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

RYAN K. ZINKE, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018

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Suggested citation:

Densmore, J.N., Woolfenden L.R., Rewis, D.L., Martin, P.M., Sneed, M., Ellett, K.M., Solt, M., and Miller, D.M., 2018, 

Geohydrology, geochemistry, and numerical simulation of groundwater flow and land subsidence in the Bicycle Basin, 

Fort Irwin National Training Center, California: U.S. Geological Survey Scientific Investigations Report 2018–5067, 

176 p., https://doi.org/10.3133/sir20185067.

ISSN 2328-0328 (online)
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Location and Description of Study Area...........................................................................................4

Previous Studies ...................................................................................................................................4

Geohydrologic Framework...........................................................................................................................6

Geology...................................................................................................................................................6

Geologic Units ..............................................................................................................................6

Structure and Depth to the Basement Complex...................................................................10

Faults .........................................................................................................................................12

Hydrologic Framework.......................................................................................................................13

Aquifer System Definitions.......................................................................................................13

Natural Recharge and Discharge ...........................................................................................15

Groundwater Pumping and Water Use..................................................................................17

Groundwater Altitudes and Movement..................................................................................17

Land-Surface Deformation.......................................................................................................27

Geochemistry of Groundwater..................................................................................................................31

General Water-Quality Characteristics and Areal Variation .......................................................32

Source and Age of Groundwater.....................................................................................................36

Stable Isotopes of Oxygen and Hydrogen .............................................................................37

Tritium and Carbon-14 ...............................................................................................................39

Groundwater-Flow Model ..........................................................................................................................41

Model Discretization ..........................................................................................................................41

Spatial Discretization ................................................................................................................41

Temporal Discretization............................................................................................................53

Model Boundaries ..............................................................................................................................53

Model Input..........................................................................................................................................54

Hydraulic Properties .................................................................................................................54

Parameter Zonation..........................................................................................................54

Hydraulic Conductivity.....................................................................................................55

Specific Yield and Specific Storage ..............................................................................55

Elastic and Inelastic Storage..........................................................................................58

Preconsolidation Head ....................................................................................................58

Horizontal-Flow Barriers ..........................................................................................................58

Simulation of Natural Recharge and Discharge...................................................................61

Groundwater Pumpage.............................................................................................................62

Model Calibration................................................................................................................................64

Pest Observation Groups and Parameter Weights ..............................................................64

Hydrograph and Observed Land-Surface Deformation and Simulated Subsidence 

Comparison ...................................................................................................................65

Simulated Hydrographs and Subsidence Time Series ........................................................65

Model Sensitivity.................................................................................................................................77

Model Results......................................................................................................................................83

Simulated Drawdown................................................................................................................83
iv

Simulated Subsidence ..............................................................................................................83

Water Budgets ...........................................................................................................................83

Model Limitations................................................................................................................................90

Simulated Effects of Runoff Capture and Future Pumpage ..................................................................90

Scenario 1: Simulated Effects of Captured Runoff........................................................................91

Simulated Effects of Future Pumpage.............................................................................................97

Scenario 2 ...................................................................................................................................97

Scenario 3 .................................................................................................................................100

Scenario 4 .................................................................................................................................106

Scenario 5 .................................................................................................................................108

Summary and Conclusions.......................................................................................................................111

References Cited........................................................................................................................................114

Appendix 1. Borehole Data for Selected Wells in Bicycle Basin at Fort Irwin National 

Training Center, California, 1993–2011 ......................................................................................119

References Cited...............................................................................................................................136

Appendix 2. Water-Level Data for Selected Wells in Bicycle Basin, Fort Irwin National 

Training Center, California, 1955–2015 ......................................................................................137

Appendix 3. Water-Quality Data for Selected Wells in Bicycle Basin at Fort Irwin 

National Training Center, California, 1993–2011 ......................................................................157

Contents—Continued

Figures

1. Map showing location of study area, Fort Irwin National Training Center, California......3

2. Map showing the generalized surficial geology, major faults, locations of 

groundwater monitoring sites and production wells, and geologic section lines 

in Bicycle Basin, Fort Irwin National Training Center, California..........................................5

3. Generalized geologic sections across Bicycle Basin, Fort Irwin National Training 

Center, California ..........................................................................................................................9

4. Map showing the altitude of the basement complex, wells, transient 

electromagnetic survey locations, and location of seismic lines in Bicycle Basin, 

Fort Irwin National Training Center, California.......................................................................11

5. Graphs showing comparisons of average monthly climate variables for the 

Fort Irwin National Training Center, San Bernardino County, California...........................16

6. Graphs showing pumpage by production well, for Bicycle Basin, Fort Irwin 

National Training Center, California.........................................................................................18

7. Map showing water levels measured at production wells, test wells, and 

shallowest wells at multiple-well monitoring sites, Bicycle Basin, Fort Irwin 

National Training Center, California.........................................................................................21

8. Hydrographs showing water-surface altitude in production and monitoring wells 

in Bicycle Basin, Fort Irwin National Training Center, California........................................23

9. Map showing subsidence in Bicycle Basin, Fort Irwin National Training 

Center, California ........................................................................................................................30

10. Trilinear diagrams showing water-quality data for selected wells in the following 

areas in Bicycle Basin, Fort Irwin National Training Center, California ............................33

11. Map showing water-quality diagrams and dissolved-solids concentrations of 

groundwater from selected wells in Bicycle Basin, Fort Irwin National Training 

Center, California ........................................................................................................................34
v

12. Graphs showing stable isotopes of groundwater samples from Fort Irwin National 

Training Center, California, along with reported weighted-average precipitation 

measurements.............................................................................................................................38

13. Map showing tritium and carbon-14 activities for groundwater from selected 

wells, Bicycle Basin, Fort Irwin National Training Center, California ................................40

14. Map showing location of local and regional groundwater-flow model grids, 

Fort Irwin National Training Center, California.......................................................................42

15. Maps showing active model cells, parameter zones, wells perforated in each 

layer, recharge cells, drain cells, and modeled faults for Bicycle Basin, Fort Irwin 

National Training Center, California.........................................................................................43

16. Cross-sectional view across Bicycle Basin, Fort Irwin National Training Center, 

California, showing generalized geologic sections and model layers ..............................47

17. Maps showing thickness of model layers in the groundwater-flow model for the 

Bicycle Basin, Fort Irwin National Training Center, California............................................49

18. Maps showing thickness of fine-grained deposits in parameter zone 6 for the 

Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, 

California, for instantaneous compaction ..............................................................................59

19. Map showing watersheds that contribute recharge to Bicycle Basin, washes, 

and groundwater-flow model boundary for the Bicycle Basin groundwater-flow 

model, Fort Irwin National Training Center, California..........................................................63

20. Graphs showing simulated heads from the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.......................................................................67

21. Graphs showing simulated subsidence from the Bicycle Basin groundwater-flow 

model, Fort Irwin National Training Center, California..........................................................69

22. Graphs showing measured groundwater levels and simulated heads in wells 

in the Bicycle Basin groundwater-flow model, Fort Irwin National Training 

Center, California ........................................................................................................................71

23. Graph showing relative composite sensitivities for the 50 most sensitive 

parameters for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California.........................................................................................................82

24. Maps showing simulated drawdown from the end of the predevelopment 

period (before 1964) to the end of the simulation period in December 2010 for 

the groundwater-flow model of the Bicycle Basin, Fort Irwin National Training 

Center, California ........................................................................................................................84

25. Map showing simulated subsidence at the end of the simulation period in 

December 2010 for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California.........................................................................................85

26. Graphs showing simulated ground-water budget components for the Bicycle 

Basin groundwater-flow model, Fort Irwin National Training Center, California.............88

27. Maps showing location of runoff-capture cells for scenario 1 using the Bicycle 

Basin groundwater-flow model, Fort Irwin National Training Center, California.............92

28. Graphs showing simulated subsidence from the Bicycle Basin groundwater-flow 

model, Fort Irwin National Training Center, California..........................................................96

29. Maps showing simulated drawdown in model layer 6 from the end of the 

historical period in December 2010 to the end of the projected period in 

December 2060 for the groundwater-flow model of the Bicycle Basin, Fort Irwin 

National Training Center, California.........................................................................................98

Figures—Continued
vi

30. Hydrographs showing measured groundwater levels during the historical period 

and simulated heads for scenario 2 during the historical and projected periods 

for the Bicycle Basin groundwater-flow model, Fort Irwin National Training 

Center, California ......................................................................................................................101

31. Graphs showing observed land-surface deformation from 1993 through 2010 and 

simulated subsidence from 1993 through 2060 for the Bicycle Basin groundwaterflow model, Fort Irwin National Training Center, California...............................................103

32. Graphs showing measured groundwater levels and simulated heads for 

scenario 3 for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California.......................................................................................................105

33. Graphs showing measured groundwater levels and simulated heads for 

scenario 4 for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California.......................................................................................................107

34. Graphs showing measured groundwater levels and simulated heads for 

scenario 5 for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California.......................................................................................................109

1–1. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BLA2, drilled 

in Bicycle Basin, Fort Irwin National Training Center, California......................................131

1–2. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BA1, drilled in 

Bicycle Basin, Fort Irwin National Training Center, California..........................................132

1–3. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BLA4, drilled 

in Bicycle Basin, Fort Irwin National Training Center, California......................................133

1–4. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BLA3, drilled 

in Bicycle Basin, Fort Irwin National Training Center, California......................................134

1–5. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BLA5, drilled 

in Bicycle Basin, Fort Irwin National Training Center, California......................................135

1–6. Stratigraphic columnar sections showing a geophysical log, well-construction 

diagram, and stratigraphic column for borehole of monitoring site BLA1, drilled 

in Bicycle Basin, Fort Irwin National Training Center, California......................................136

Figures—Continued

Tables

1. Summary of construction data for production and monitoring wells in the Bicycle 

Basin, Fort Irwin Training Center, California.............................................................................7

2. Summary of aquifer-test results from various studies in Bicycle Basin, Fort Irwin 

National Training Center, California, 1955–2008.....................................................................14

3. Annual pumpage, in acre-feet, for Bicycle Basin at Fort Irwin National Training 

Center, California, 1967–2010 ....................................................................................................19

4. Comparison of minimum, maximum and average monthly pumpage, in acre-feet, 

for Bicycle Basin, Fort Irwin National Training Center, California, 1991 to 2010 ..............20

5. Acquisition dates of synthetic aperture radar data, interferogram timelines, and 

subsidence magnitudes and rates for 72 interferograms analyzed for Bicycle Lake 

Basin, Fort Irwin National Training Center, California, 1992–2010......................................28
vii

6. Model-layer thickness in the groundwater flow model of Bicycle Basin, Fort Irwin 

National Training Center, California.........................................................................................53

7. Number of hydraulic-parameter zones in model layers 1–8 of the Bicycle Basin 

groundwater-flow model, Fort Irwin National Training Center, California ........................54

8. Summary of initial and final parameter estimates used in the groundwater-flow 

model of Bicycle Basin, Fort Irwin National Training Center, California ...........................56

9. Summary of initial and final hydraulic characteristics for horizontal-flow barriers 

in the groundwater-flow model of Bicycle Basin, Fort Irwin National Training 

Center, California ........................................................................................................................61

10. Summary of initial and final groundwater–recharge values for the groundwaterflow model of the Bicycle Basin, Fort Irwin Training Center, California............................62

11. Summary of model-fit statistics for differences between measured water levels 

and simulated heads for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California.........................................................................................66

12. Summary of model-fit statistics for differences between observed land-surface 

deformation and simulated subsidence for the Bicycle Basin groundwater-flow 

model, Fort Irwin National Training Center, California..........................................................66

13. Summary of average, minimum, and maximum vertical differences in measured 

water levels and simulated heads, and direction of flow for multiple-well 

monitoring sites for 1997–2010 in the Bicycle Basin, Fort Irwin National Training 

Center, California ........................................................................................................................76

14. Parameter names, relative composite sensitivity values, and sensitivity rank in 

the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, 

California ......................................................................................................................................77

15. Simulated predevelopment and transient (1967–2010) groundwater budgets for 

the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, 

California ......................................................................................................................................86

16. Runoff-capture and pumping-management scenarios, 2010–60, for the Bicycle 

Basin groundwater-flow model, Fort Irwin National Training Center, California.............91

17A. Estimated total runoff for scenario 1 by the Bicycle Basin groundwater-flow 

model, Fort Irwin National Training Center, California..........................................................94

17B. Estimated runoff available for capture for scenario 1 by the Bicycle Basin 

groundwater-flow model, Fort Irwin National Training Center, California ........................94

17C. Estimated actual runoff rate applied to the runoff-capture model cells for 

scenario 1 by the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California.........................................................................................................95

18. Summary of simulated total groundwater budget, in acre-feet, for the Bicycle 

Basin groundwater-flow model, runoff-capture scenario, and future-pumpage 

scenarios, Bicycle Basin groundwater-flow model, Fort Irwin National Training 

Center, California ........................................................................................................................95

1–1. Lithologic log from sieve samples for multiple-well monitoring site BLA2, Bicycle 

Basin, Fort Irwin National Training Center, California ........................................................119

1–2. Lithologic log from sieve samples for multiple-well monitoring site BA1, Bicycle 

Basin, Fort Irwin National Training Center, California ........................................................120

1–3A. Lithologic log from sieve samples for multiple well monitoring site BLA4, Bicycle 

Basin, Fort Irwin National Training Center, California ........................................................121

1–3B. Lithologic log from shaker samples for multiple well monitoring site BLA4, Bicycle 

Basin, Fort Irwin National Training Center, California ........................................................122

Tables—Continued
viii

1–4. Lithologic log from sieve samples for multiple-well monitoring site BLA3, Bicycle 

Basin, Fort Irwin National Training Center, California ........................................................125

1–5A. Lithologic log from sieve samples and for multiple-well monitoring site BLA5, 

Bicycle Basin, Fort Irwin National Training Center, California..........................................127

1–5B. Lithologic log from shaker samples for multiple-well monitoring site BLA5, 

Bicycle Basin, Fort Irwin National Training Center, California..........................................129

1–6. Lithologic log of sieve samples log for multiple-well monitoring site BLA1, 

Bicycle Basin, Fort Irwin National Training Center, California..........................................130

2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National 

Training Center, California, 1955–2015...................................................................................137

3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National 

Training Center, California, 1993–2011...................................................................................158

Tables—Continued

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

inch (in.) 12 foot (ft)

inch (in.) 25,400 micrometer (μm)

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)

Volume

cubic foot (ft3

) 0.02832 cubic meter (m3)

ounce, fluid (fl. oz) 29.5735 milliliter (mL)

acre-foot (acre-ft) 43,560 cubic feet (ft3

)

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

)

Flow rate

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

/yr)

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

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

inch per second (in/s) 6.675 millimeter per month (mm/mo)

inch per month (in/mo) 9.66513 millimeter per second (mm/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

Specific capacity

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

Hydraulic conductivity

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

Transmissivity

foot squared per day (ft2

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

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

°F = (1.8 × °C) + 32.

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

°C = (°F – 32) / 1.8.

Datum

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

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

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

Supplemental Information

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

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

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

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

25 °C).

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

or micrograms per liter (μg/L).

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

Results for measurements of stable isotopes of an element (with symbol E) in water, solids, 

and dissolved constituents commonly are expressed as the relative difference in the ratio of 

the number of the less abundant isotope (iE) to the number of the more abundant isotope of a 

sample with respect to a measurement standard.

Abbreviations

As arsenic

bls below land surface

14C carbon-14

Cl chloride

D deuterium 

F fluoride

H hydrogen

2

H deuterium

3

H tritium
x

HCO3 bicarbonate

Hchar Hydraulic characteristic

HK horizontal hydraulic conductivity

InSAR interferometric synthetic aperture radar

Na sodium

NO3 nitrate

NTC National Training Center

O oxygen

18O oxygen-18

pmC percent modern carbon

PVC polyvinyl chloride

PET potential evapotranspiration

RMSE root-mean-squared error

SO4 sulfate

SP spontaneous potential

Ske elastic skeletal specific storage (for instantaneous compaction)

Sske elastic skeletal specific storage (for delayed compaction)

Skv inelastic skeletalspecific storage (for instantaneous compaction)

Sskv inelastic skeletalspecific storage (for delayed compaction)

SS specific storage

SY specific yield

TEM transient electromagnetic 

TDS total dissolved solids

TU tritium units

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VANI vertical anisotropy, defined as ratio of HK to VK

Vki vertical hydraulic conductivity (for delayed compaction)

VK vertical hydraulic conductivity

VSMOW Vienna Standard Mean Ocean Water

Bc basement complex

Qoa Quaternary older alluvium

Qp Quaternary playa deposits

Qya Quaternary younger alluvial deposits

Abbreviations—Continued
xi

QToa Quaternary-Tertiary older alluvium

QTol Quaternary-Tertiary older clay lacustrine

Tog Tertiary older alluvium

Tv Tertiary volcanic rocks

Tyg Tertiary younger alluvium

Well-numbering System

Abbreviations—Continued

R4ER3E R5E

 T15N

 T14N

 T13N

RANGE

PIHSNWOT

 R1W R1E

27

R3E

T14N

Well-numbering diagram

3456 2 1

7

18 13

8 9 10 11 12

17 16 1415

19 24

30 25

31 36

20 21 22 23

262829

32 33 34 35

SECTION 13

ACD

E F G H

JKLM

N P Q R

B

14N/3E-13A1

San Bernardino

Meridian

Wells are assigned a state well number (station name) by the California Department of Water 

Resources according to the location in the rectangular township and range grid system 

for the subdivision of public lands. Station names consist of the township number, north or 

south; the range number, east or west; and the section number. Each section is divided into 

sixteen 40-acre tracts lettered consecutively (except “I” and “O”), beginning with “A” in the 

northeast corner of the section and progressing in a sinusoidal manner to “R” in the southeast 

corner. Within the 40-acre tract, numbers are assigned sequentially in the order the wells 

are inventoried. The next letter within the station name refers to the base line and meridian. 

California has three base lines and meridians—Humboldt (H), Mount Diablo (M), and San 

Bernardino (S). Wells in the study area are referenced to the San Bernardino and Mount Diablo 

base line and meridian (S and M). Well numbers consist of 15 characters and follow the format 

012N003E01M001S. In this report, wells are abbreviated and written as 12N/03E-01M1S. Wells 

are abbreviated in figures by their section number, tract letter, and sequence number (for 

example, 1M1). In addition to a station name assigned by the California Department of Water 

Resources, wells were assigned a common name derived from the basin in which they were 

installed and a sequence number. Wells were also assigned a 15-digit site identification number 

in the U.S. Geological Survey National Water Information System database.

Geohydrology, Geochemistry, and Numerical Simulation 

of Groundwater Flow and Land Subsidence in the Bicycle 

Basin, Fort Irwin National Training Center, California

By Jill N. Densmore, Linda R. Woolfenden, Diane L. Rewis, Peter M. Martin, Michelle Sneed, Kevin M. Ellett1, 

Michael Solt2

, and David M. Miller

Abstract

Groundwater pumping from Bicycle Groundwater Basin 

(referred to as Bicycle Basin) in the Fort Irwin National 

Training Center, California, began in 1967. From 1967 to 

December 2010, about 46,000 acre-feet of water had been 

pumped from the basin and transported to the Irwin Basin. 

During this time, not only did water levels in the basin decline 

by as much as 100 feet, the quality of the groundwater pumped 

from the basin also deteriorated in some wells.

 The U.S. Geological Survey collected geohydrologic 

data from existing wells, test holes, and 16 additional 

monitoring wells installed at 6 sites in Bicycle Basin 

during 1992–2011 to determine the quantity and quality of 

groundwater available in the basin. Geophysical surveys, 

including electrical, gravity, and seismic refraction surveys, 

were completed to help determine the geometry of the 

structural basin, delineate depths to the interface between 

Quaternary and Tertiary rocks, map the depth to the water 

table, and used to develop a geohydrologic framework and 

groundwater-flow model for Bicycle Basin. 

Water samples were used to determine the groundwater 

quality in the basin and to delineate potential sources of 

poor-quality groundwater. Analysis of stable isotopes of 

oxygen and hydrogen in groundwater indicated that presentday precipitation is not a major source of recharge to the 

basin. Tritium and carbon-14 data indicated that most of the 

groundwater in the basin was recharged prior to 1952 and had 

an apparent age of 15,625–39,350 years. Natural recharge 

to the basin was not sufficient to replenish the groundwater 

pumped from the basin. Interferograms from synthetic 

aperture radar data (InSAR), analyzed to evaluate land-surface 

subsidence between 1993 and 2010, showed 0.23 to 1.1 feet of 

subsidence during this period near one production well north 

of Bicycle Lake (dry) playa.

A groundwater-flow model of Bicycle Basin was 

developed and calibrated using groundwater levels for 1964–

2010, and a subsidence model using land-surface deformation 

data for 1993–2010. Between January 1967 and December 

2010, the simulated total recharge from precipitation runoff 

and underflow from adjacent basins was about 5,100 acre-feet 

and pumpage from the Bicycle Basin was about 47,000 acrefeet of water. Total outflows exceeded natural recharge during 

this period, resulting in a net loss of about 42,100 acre-feet of 

groundwater storage in the basin.

The Fort Irwin National Training Center is considering 

various groundwater-management options in the Bicycle 

Basin. The groundwater-flow model was used to (1) evaluate 

changes in groundwater levels and subsidence with the 

addition of capture and recharge of simulated runoff in 

retention basins (scenario 1) for predevelopment through 

2010; (2) simulate a base case (scenario 2) for reference; 

and (3) compare projections of alternative future pumping 

strategies for 2011–60 (scenarios 3–5). 

Model results from the runoff-capture simulation 

(scenario 1) indicated that total recharge, including runoff 

captured using retention basins, locally increased water levels, 

which partially offset, but did not mitigate, groundwater 

depletion associated with pumping. Groundwater-storage 

depletion in scenario 1 was about 14 percent less than without 

runoff capture. Simulated-drawdown results in model layer 

1 in the eastern part of the basin indicated that, because 

of the captured runoff, simulated heads were as much as 

100 feet higher in December 2010 than prior to the onset of 

development in 1967. In contrast, simulated drawdown for 

model without runoff capture indicated that, without captured 

runoff, simulated heads for December 2010 in this area were 

80–90 feet lower than during the predevelopment period. 

Subsidence was mitigated slightly in scenario 1 compared to 

without runoff capture; the largest decrease in subsidence at 

observation sites was about 0.07 feet.

1

Indiana Geological and Water Survey, Indiana University.

2

Langan Engineering and Environmental Services.
2 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Scenario 2 results indicated that simulated drawdown 

in model layer 6 at the end of 2060 ranged from about 46 to 

135 feet. Subsidence at observation sites at the end of 2060 

ranged from 0.83 to 2.8 feet. Reducing the base case pumping 

rate by 25 percent in the existing production well in the 

subsidence area and redistributing the pumpage to the other 

two production wells (scenario 3) resulted in a reduction of 

drawdown in the subsidence area compared with the base 

case (scenario 2). The difference in subsidence at the end of 

2060 between scenario 3 and the base case was small (less 

than 0.07 feet) for all observation locations. Repeating the 

simulation scenario 3 but additionally reducing the basinwide pumpage by 3 percent per year from 2011 through 

2020 (scenario 4) resulted in about 60 feet less drawdown 

in the subsidence area than for the base case. Subsidence at 

observation sites ranged from 0.12 to 0.43 feet less than for the 

base case. Reducing the pumpage in the existing production 

well in the subsidence area to zero, while continuing the base 

case pumping rate in the other two existing production wells 

(scenario 5), resulted in more than 100 feet less drawdown 

in the subsidence area than in the base case. The simulated 

subsidence at the end of 2060 ranged from about 0.19 to 

about 1.16 feet less than in the base case, indicating that the 

discontinuation of pumpage at well 14N/3E-14P1 would result 

in substantially reduced subsidence. 

Overall, continued water-table declines dewatered the 

more productive upper layers of the aquifer, causing more 

groundwater to be withdrawn from deeper, lower yielding 

layers and resulting in faster declines in the water table and 

greater vertical gradients in the future. If the water table 

declines into the perforated intervals of wells, increased 

maintenance costs and altered well-water quality could 

potentially result. Water-management scenario 1 indicated 

that adding managed recharge resulted in a modest decrease 

(4–5 percent) in the rate of subsidence compared with 

historical conditions. The reduction of pumpage in the area 

of subsidence and redistribution of the amount of reduced 

pumpage to wells in other parts of the basin (scenario 3) 

resulted in modest decreases (5–6 percent) in the rate of 

subsidence compared with continuation of historical pumpage. 

Including either a basin-wide reduction of pumpage of 

3 percent annually (cumulatively, a 24 percent decrease) 

as well as redistribution of the pumpage (scenario 4) or 

discontinuing pumping in the area of greatest subsidence 

(scenario 5), however, demonstrated that subsidence could 

be reduced substantially (22–26 percent for scenario 4 and 

62–68 percent for scenario 5) compared with subsidence for 

continuing historical pumpage.

Introduction

Fort Irwin National Training Center (NTC) in the Mojave 

Desert of southern California has been used as a military 

training facility almost continuously since August 1940. 

Fort Irwin NTC obtains its potable water (as of 2018) from 

groundwater in the Irwin, Bicycle, and Langford Groundwater 

Basins (fig. 1). Groundwater pumpage exceeds natural 

recharge, resulting in water-level declines in these basins. 

Several production wells have been abandoned or destroyed 

because of water-quality concerns. To effectively manage 

the water resources and plan for future water needs at Fort 

Irwin NTC, a complete understanding of the geohydrologic 

and geochemical framework of Irwin, Langford, and Bicycle 

Basins is needed.

In 1992, the U.S. Geological Survey (USGS) entered into 

an agreement with Fort Irwin NTC to monitor and evaluate 

the groundwater resources of the Fort Irwin NTC. The reader 

is referred to Densmore and Londquist (1997), Densmore 

(2003), Voronin and others (2013), and Voronin and others 

(2014) for more information. The work presented in this report 

was completed under a continuation of this agreement. The 

objectives of the study are to describe the geohydrologic and 

geochemical framework of the groundwater basins that supply 

water to the Fort Irwin NTC, to develop groundwater-flow 

models that help refine the understanding of the geohydrology 

of these basins, and to use this information to evaluate the 

long-term availability of groundwater for the Fort Irwin NTC. 

Purpose and Scope

This report describes the geohydrologic and geochemical 

framework of Bicycle Basin and how the information was 

utilized to develop a groundwater-flow model for Bicycle 

Basin to evaluate the long-term availability of groundwater in 

the basin. 

Available geohydrologic and geochemical data were 

compiled for the Bicycle Basin, and new data were collected 

from existing wells. Additional work included geophysical 

surveys (gravity, seismic refraction, and time-domain 

electromagnetic induction) to refine understanding of the size 

and shape of the basin and provide additional information 

about the stratigraphy. Monitoring wells were installed during 

1993–2011 to provide depth-dependent geohydrologic and 

geochemical data. 

Water-quality samples were collected and analyzed for 

major ions and trace elements to evaluate possible sources of 

groundwater-quality degradation. Samples also were analyzed 

for the stable isotopes oxygen-18 (18O) and deuterium (D) to 

determine the source of groundwater and for the radioactive 

isotopes of tritium (3H) and carbon-14 (14C) to evaluate the 

relative age of groundwater (years since the water entered the 

groundwater system) in the basin. 

A conceptual model of the geohydrologic system was 

developed using data compiled and collected for this study, 

including lithologic and geophysical data from available 

boreholes (data shown in appendix 1). The conceptual 

model and groundwater-level data were used to develop and 

calibrate a groundwater-flow model of the Bicycle Basin. 
Introduction 3

sac11-0424_fig 01

395

58

15

15

40

Edwards

Air Force

Base

China Lake 

Naval Weapons

Center

China Lake 

Naval Weapons

Center

Fort Irwin 

National Training

Center

Cuddeback Lake

Air Force Range

Bicycle

Basin

Langford

Basin

Irwin

Basin

M o j a v e

D e s e r t

Study

area

(see fig. 2)

 Garlic

Spring

 West Cronise Valley

Coyote 

Lake

Basin

Noble

Dome

Tiefort

Mountain

San BernardinoBarstow Northeast #134

Daggett FAA Airport

Dunn Siding 

Goldstone

Echo 2

Barstow Fire

Station

GARLOCK

 FAULT

ZONE 

Goldstone

Barstow

IRWIN RD

 Alvord

Mountain

Granite Mountains

Mojave Desert

 Los

Angeles

 San

Francisco CALIFORNIA

Map 

area

EXPLANATION

Goldstone Echo 2, California (043498)

Daggett FAA Airport, California (042257)

Barstow Fire Station, California (040521)

Dunn Siding, California (042570)

Western Regional Climate Center (WRCC) station

San Bernardino−Barstow Northeast - #134 

California Irrigation Management Information

 System (CIMIS) station

Goldstone Deep Space Communications Complex

Drainage basin (California Interagency Watershed

 Mapping Committee, 2004)

Bicycle groundwater basin (modified from 

 Wilson F. So and Associates, Inc., 1989)

Regional model boundary

Fort Irwin National Training Center boundary

Other military boundaries

117°30' 117° 116°30'

35°30'

35°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey and other Federal and State digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

Figure 1. Location of study area, Fort Irwin National Training Center, California.
4 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The groundwater-flow model is intended to provide a better 

understanding of the geohydrology of the basin and to help 

estimate the long-term availability of groundwater from the 

basin by evaluating changes in groundwater-level altitudes (or 

hydraulic heads) under different runoff-capture and pumping 

scenarios. The model also was used to evaluate the subsidence 

caused by continued pumping and its effect on fissuring that 

has developed on Bicycle Lake (dry) playa.

Location and Description of Study Area

Fort Irwin NTC is about 130 miles (mi) northeast of Los 

Angeles in the Mojave Desert region of southern California 

(fig. 1). The NTC covers an area of about 1,177 square miles 

(mi2) that contain several surface-water drainage basins, 

including Irwin, Bicycle, and Langford Basins. Bicycle Basin 

is near the center of Fort Irwin NTC, about 35 mi northeast of 

Barstow, California. 

Bicycle Groundwater Basin (fig. 1), referred to as 

Bicycle Basin in this report, lies in the southeastern part of the 

much larger Bicycle Valley drainage basin (about 140 mi2); 

the Bicycle Basin covers an area of about 10.5 mi2 (fig. 1). 

Bicycle Basin, typical of desert basins in the Mojave Desert, 

is a closed basin with a relatively flat floor surrounded by 

generally rugged mountains or low-lying hills. Bicycle 

Valley drainage basin is bounded to the north by the Granite 

Mountains, to the east by Tiefort Mountain, to the south by 

low-lying hills that separate Bicycle Basin from Irwin Basin, 

and to the west by low-lying hills that separate Bicycle Basin 

from the highlands near Goldstone (fig. 1). Bicycle Lake (dry), 

a playa, lies in the southern part of Bicycle Basin (fig. 2). The 

floor of Bicycle Basin ranges in altitude from about 2,350 feet 

(ft) North American Vertical Datum of 1988 (NAVD 88) at 

the playa to about 2,600 ft at the base of Tiefort Mountain. 

No perennial streams are present in the basin, but the washes 

can flow for several days after large storms. Surface water 

in Bicycle Basin drains to the playa, the lowest part of the 

basin. No vegetation grows on Bicycle Lake (dry) playa or 

on its margins; however, a small, vegetated area that might 

be supported by a localized, shallow perched zone or a 

buried well described in Mendenhall (1909, p. 54), is in the 

northeastern part of the playa.

The climate of Bicycle Basin, typical of the Mojave 

Desert region, is characterized by low precipitation, hot 

summers, and cool winters. Sporadic weather records for 

2003–08 were available for Bicycle Basin. Weather records 

were available for nearby Goldstone, about 11 mi west of 

the basin, for 1973–2006 (Western Region Climate Center, 

2009) and for Barstow for 1943–2013 (National Oceanic 

and Atmospheric Administration, 1994, 2010, 2013), which 

indicated average annual precipitation was about 7 inches (in.) 

and ranged from 2 to 15 in. between 1950 and 2013). Most 

precipitation falls during the winter, but some precipitation 

from isolated thunderstorms falls during the summer months. 

The average annual temperature at Barstow between 1940 and 

2009 was 64 degrees Fahrenheit (°F), and temperatures ranged 

from 3 to 121 °F (EarthInfo, Inc., 1995, 2000; California 

Irrigation Management Information System, station 134, 

1997–2013, accessed February 17, 2009, at http://wwwcimis.

water.ca.gov/Stations.aspx, replaced by station 234, 2015–16, 

accessed June 26, 2016). The average annual potential 

evapotranspiration was about 140 in. for Death Valley (1961–

2005, accessed July 26, 2016, at https://wrcc.dri.edu/Climate/

comp_table_show.php?stype=pan_evap_avg), about 35 mi 

northeast of the basin, and about 78 in. at Newberry Springs 

(not shown on fig. 1), about 25 mi to the south (1987–99, 

California Department of Water Resources, p. 25, accessed 

July 26, 2016, at http://www.water.ca.gov/wateruseefficiency/

docs/MWELO09-10-09.pdf).

Previous Studies

Previous studies of Bicycle Basin have been completed 

by the USGS and by several consulting and engineering 

companies. Kunkel and Riley (1959) reported on a 

geological reconnaissance of the basin. Yount and others 

(1994) and Schermer and others (1996) published detailed 

geologic maps. Groundwater-availability studies were 

published by C.F. Hostrup and Associates (1955), James M. 

Montgomery and Associates (1981), and Wilson F. So and 

Associates (1989). In conjunction with the present study, 

gravity data collected during 1999 and 2010–11 were used 

to develop a depth-to-basement map and the subsequent 

altitude of the basement complex (Jachens and Langenheim, 

2014). A seismic-refraction survey was used to provide 

information about different lithologic layers (David Berger, 

U.S. Geological Survey, written commun., 1996).
Introduction 5

sac11-0424_fig 02

South Coyote Canyon fault

26K1,3,4

18N1 18N2

35C4

35C1

35C2,3

28H2

28H1

28A1

27E2

27E3

27E1

24Q1–5

24H1 23G1

23B1–3

22P1

22N1,2

14P2 14P1

14H1 13M2–4

13M1

13K1

116°40’ 116°38’ 116°36’

35°18’ 35°16’

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

A

A’

B

B’

Unnamed fault 2

Unnamed thrust fault

North Bicycle Lake fault

0 0.5 1 MILE

0 0.5 1 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

R. 3 E. R. 4 E.

T.

14

N.

EXPLANATION

Well type and identifier (see table 1) Bicycle groundwater basin (California 

 Interagency Watershed Mapping 

 Committee, 2004)

Basement

complex

Quaternary younger alluvium (Qya)

Quaternary playa (Qp)

Quaternary and Quaternary-Tertiary

 older alluvium (Qoa and QToa)

Tertiary deposits (Tyg, Tog, and Tp)

Tertiary volcanic (Tv)

Carbonate rock (marble, dolomite, 

or limestone)

Pre-Tertiary granitic rocks

Pre-Tertiary metamorphic rocks

Geology (Miller and others, 2014)

Section A–A’

Section B–B’

Township/range

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

26K1

35C1

22P1

23G1

Bicycle Lake

(dry)

Irwin

Basin

24H1

Figure 2. Generalized surficial geology, major faults, locations of groundwater monitoring sites and production wells, and geologic 

section lines in Bicycle Basin, Fort Irwin National Training Center, California.
6 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Geohydrologic Framework

The geohydrologic framework of the Bicycle Basin 

was developed by evaluating information from previously 

published reports, by doing geophysical surveys, and by 

collecting geologic and hydrologic data from existing and 

newly drilled wells. Table 1 lists the local well name, state 

well number, and well-construction data for all wells used in 

this report.

Geology

The geology of Bicycle Basin was previously described 

by C.F. Hostrup and Associates (1955), Kunkel and Riley 

(1959), James M. Montgomery and Associates (1981), 

Wilson F. So and Associates (1989), Yount and others (1994), 

Schermer and others (1996), and Miller and Yount (2002). 

The geologic discussion presented in this report summarizes 

information from these reports and updates the geology on the 

basis of work completed as part of this study.

Geologic Units

For this study, the geologic units are grouped into five 

generalized units: (1) pre-Tertiary basement complex (Bc), 

(2) Tertiary volcanic rocks (Tv), (3) Tertiary sedimentary 

deposits (Tog, Tp, and Tyg), (4) Quaternary-Tertiary older 

alluvium and lacustrine deposits (QToa and QTol), and 

(5) Quaternary older and younger alluvium and playa 

deposits (Qoa, Qya, and Qp). The older and younger Tertiary 

sedimentary deposits and Quaternary-Tertiary lacustrine 

deposits (Tog, Tyg, and QTol) are in the subsurface, but 

not mapped at the surface. The structural and stratigraphic 

relationships in Bicycle Basin are presented in figures 2 and 3. 

The basin fill represents the water-bearing deposits that consist 

of Tertiary sedimentary deposits (Tog and Tyg), QuaternaryTertiary older alluvium and lacustrine deposits (QToa and 

QTol), Quaternary older alluvium and clay, Quaternary 

younger alluvium, and Quaternary playa deposits (Qoa, Qya, 

and Qp). These deposits are unconsolidated at land surface and 

become moderately to well consolidated with depth.

The basement complex is exposed in the hills 

surrounding Bicycle Basin and underlies the basin (figs. 2, 

3). The pre-Tertiary basement complex consists of mostly 

felsic and mafic plutonic rocks; metamorphic rocks 

consisting of marble, quartzite, and schist; carbonate rock 

consisting of dolomite or limestone; and metasedimentary 

and metavolcanic rocks (Yount and others, 1994; Schermer 

and others, 1996; Miller and Yount, 2002). Volcanic rocks 

(Yount and others, 1994) crop out in the hills to the northwest, 

west, and southwest of Bicycle Basin (Schermer and others, 

1996; Miller and Yount, 2002). Although it is possible that 

these volcanic rocks underlie at least part of the basin fill, no 

boreholes have penetrated them. The basement complex has 

low permeability, and water generally is contained only where 

these rocks are extensively jointed, fractured, or weathered. 

Although the “weathered” zone of the basement complex 

might contain water, it was considered non-water-bearing 

because it is likely that only small amounts of groundwater are 

stored in the fractures (Densmore and Londquist, 1997). 

Tertiary volcanic rocks (Tv) are exposed south and west 

of Bicycle Basin along an approximately north-trending, lowlying ridge in the Bicycle Lake fault zone as well as northwest 

of the basin in several fault blocks on the south side of and 

in the Coyote Canyon fault zone (fig. 2). This distribution 

correlates with lava that flowed from the southeast, through 

what is now Bicycle Basin, and to the northwest (Miller 

and Yount, 2002, fig. 11). Time-domain or transient 

electromagnetic (TEM) surveys (Burgess and Bedrosan, 2014) 

in the southwestern part of the basin and west of Bicycle Lake 

(dry) playa showed higher resistivity at depth, and seismic 

surveys showed layers with higher seismic wave velocity at 

depth, as described in the next section. These geophysical data 

indicated a different layer with higher resistivity and seismic 

wave velocity is present at depth; this layer could represent 

buried volcanic rock, although no boreholes were present 

west of the playa to confirm. The Tertiary volcanic rocks 

(Tv) generally have low permeability, and water generally 

is contained only where these rocks are extensively jointed, 

fractured, or weathered.

Tertiary sedimentary deposits are exposed in the lowlying hills to the north, west, and south of Bicycle Basin; 

they overlie the basement complex and partially fill the basin 

(Miller and Yount, 2002; figs. 2, 3). These deposits include 

older gravels (Tog), younger gravels (Tyg), and paludal 

deposits (Tp, which are typically fine-grained evaporates, clay, 

silt, and fine sand deposited in spring or marsh environments; 

Yount and others, 1994). The older and younger gravels (Tog 

and Tyg) are moderately to well consolidated, poorly sorted 

coarse sands and gravels to boulder-sized clasts, primarily 

derived of granitic and volcanic material; the older gravels 

(Tog), which are more consolidated, are much less permeable 

than the overlying younger gravels (Tyg; see “Aquifer System 

Definitions” section). The paludal deposits (Tp) tend to 

coarsen upward and laterally to sand and pebble conglomerate 

of the Tertiary younger gravel (Tyg). Where sand and gravel 

predominate, the Tertiary deposits might yield moderate 

amounts of groundwater to wells. 
Table 1. Summary of construction data for production and monitoring wells in the Bicycle Basin, Fort Irwin Training Center, California.[Location of wells are shown in figure 2. Abbreviations: Bc, basement complex; D, well destroyed; ft, feet; ID, identification; M, monitoring well; NA, well not in model domaVertical Datum of 1988; P, production well; Qoa, Quaternary older alluvium; QToa, QToa1, QToa2, Quaternary-Tertiary older alluvium; QTol, Qaternary-Tertiary older lacustrinalluvium; Tog, Tertiary older gravels; TW, test well; Tyg, Tertiary younger gravels; U, unused well; —, data not available]

State well 

number

Short 

ID Local ID Well type Date drilled Geology Land-surface altitude, in feet, NAVD 88 (ft) Hole depth (ft) Well depth (ft) Screen top (ft) Screen bottom (ft) 

t

14N/3E-13K1S -13K1 B-1 P1 January 1955 QToa, Tyg 2,398 600 600 180 580 

14N/3E-13M1S -13M1 B-4 P May 1965 QToa, Tyg 2,419 614 600 226 594 

14N/3E-13M2S -13M2 BLA2-1 M June 1997 Tyg 2,418 600 600 580 600 

14N/3E-13M3S -13M3 BLA2-2 M June 1997 QToa2, 1 2,418 600 440 420 440 

14N/3E-13M4S -13M4 BLA2-3 M June 1997 QToa2 2,418 600 330 310 330 

14N/3E-14H1S -14H1 B-2 P1 November 1964 QToa 2,423 602 602 230 585 

14N/3E-14P1S -14P1 B-6 P January 1988 QToa 2,380 540 535 380 525 

14N/3E-14P2S -14P2 TH-7 TW January 1988 QToa 2,380 800 535 380 525 

14N/4E-18N1S -18N1 B-5 P March 1983 QToa, Tyg, Tog 2,378 803 800 300 780 

14N/4E-18N2S -18N2 B-5A TW February 1983 QToa 2,380 803 803 302 305 

14N/3E-22N1S -22N1 BA1-1 M1 March 1993 Bc 2,418 — 260 240 260 

14N/3E-22N2S -22N2 BA1-2 M1 March 1993 QToa 2,418 — 170 150 170 14N/3E-22P1S -22P1 B-3 D — QToa 2,432 532 478 — — 

14N/3E-23B1S -23B1 BLA4-1 M December 2007 Tyg 2,377 865 850 710 730 

14N/3E-23B2S -23B2 BLA4-2 M December 2007 QToa1 2,377 865 460 440 460 

14N/3E-23B3S -23B3 BLA4-3 M December 2007 QToa2 2,377 865 280 260 280 

14N/3E-23G1S -23G1 BX-2 TW October 1980 QToa, QTol, Tyg 2,361 748 747 178 737 

14N/3E-24H1S -24H1 BX-1 TW2 October 1980 Qoa, QToa 2,362 414 413 183 403 

14N/3E-24Q1S -24Q1 BLA3-1 M July 1997 Tog 2,356 900 898 878 898 

14N/3E-24Q2S -24Q2 BLA3-2 M July 1997 Tog 2,356 900 745 725 745 

14N/3E-24Q3S -24Q3 BLA3-3 M July 1997 Tyg 2,356 900 610 590 610 

14N/3E-24Q4S -24Q4 BLA3-4 M July 1997 QToa1 2,356 900 450 430 450 

14N/3E-24Q5S -24Q5 BLA3-5 M July 1997 QToa2 2,356 900 310 290 310 

14N/3E-26K1S -26K1 BLA5-1 M March 2011 Tyg 2,345 370 360 320 340 14N/3E-26K2S3 -26K2 BLA5-2 M March 2011 QToa 2,345 370 210 190 210 

14N/3E-26K3S -26K3 BLA5-3 M March 2011 QToa 2,345 370 210 190 210 14N/3E-26K4S -26K4 BLA5B- 1 M March 2011 QToa 2,345 280 270 250 270 

14N/3E-27E1S -27E1 BP-2, MW-12 TW — Tog 2,401 — — — — 14N/3E-27E2S -27E2 BP-3, MW-13 TW — Tog 2,401 — — — — 
State well number Short ID Local ID Well type Date drilled Geology Land-surface altitude, in feet, NAVD 88 (ft) Hole depth (ft) Well depth (ft) Screen top (ft) Screen bottom (ft) 

t

14N/3E-27E3S -27E3 BP-4, MW-14 TW — Tog 2,401 — — — — 14N/3E-28A1S -28A1 BP-MW22 TW — Tog 2,411 — 151.28 — — 14N/3E-28H1S -28H1 BP-1, MW-11 TW — Tog 2,407 — — — — 

14N/3E-28H2S -28H2 BP-MW21 TW — Tog 2,401 — 164.32 — — 14N/3E-35C1S -35C1 B-9_Aprt U March 1963 Bc 2,352 250 245 125 245 14N/3E-35C2S -35C2 BLA1-1 M May 1994 Bc 2,357 200 175 155 175 14N/3E-35C3S -35C3 BLA1-2 M May 1994 Qya 2,357 200 25 15 25 

14N/3E-35C4S -35C4 W3 TW August 1997 Bc 2,350 300 300 200 300 

1The well has been destroyed. 2The well was obstructed. 3The well was sealed and abandoned; it was replaced by site BLA5B. Table 1. Summary of construction data for production and monitoring wells in the Bicycle Basin, Fort Irwin Training Center, California.—Continued [Location of wells are shown in figure 2. Abbreviations: Bc, basement complex; D, well destroyed; ft, feet; ID, identification; M, monitoring well; NA, well not in model doma

Vertical Datum of 1988; P, production well; Qoa, Quaternary older alluvium; QToa, QToa1, QToa2, Quaternary-Tertiary older alluvium; QTol, Qaternary-Tertiary older lacustrinalluvium; Tog, Tertiary older gravels; TW, test well; Tyg, Tertiary younger gravels; U, unused well; —, data not available]
Geohydrologic Framework 9

sac11-0424_fig 03ab

Unnamed

thrust fault

Unnamed

fault 1

North Bicycle

Lake fault

35C2, 3 26K1, 3, 4

(projected)

Tyg Tyg

QToa

QToa QTol

Tog

QToa

Qya

Qoa

Bc

Bc

Qp

13M2, 3, 4

Tog

Unnamed

fault 2

BEND IN

SECTION

23G1 23B1, 2, 3

BEND IN

SECTION

PART OF

SECTION

B–B’

Tyg

QToa

QTol

Tog

Qya

Qoa

Bc

Qp

QToa

QToa

Tyg

Tog

Qoa

Qoa

24Q1, 2, 3, 4, 5 14P1 23G1

23B1, 2, 3

Qya

BEND IN

SECTION

PART OF

SECTION

A–A’

BEND IN

SECTION

Faults

Water table

Geologic unit/age

BEND IN

SECTION

A

A Aʹ

SECTION B–B’

B Bʹ

VERTICAL EXAGGERATION x1.9

NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD 88)

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

SOUTH NORTH

SECTION A–A’

South Coyote

Canyon fault Coyote

Canyon

fault

FEET

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

FEET

South Coyote

Canyon fault 3,000

2,500

2,000

1,500

1,000

500

NAVD

88

EXPLANATION

B

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

SOUTHEAST NORTHWEST

VERTICAL EXAGGERATION x1.65

NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD 88)

Qoa

QToa

Tog

QTol

Tyg

Bc

Playa/Quaternary

Younger alluvium/Quaternary

Older alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

Older lacustrine/ Quaternary-Tertiary

Qya

Qp

Well and identifier

 (see table 1)

Perforated interval

23G1

Younger alluvial gravels/Tertiary

Fine-grained deposits

Older alluvial gravels/Tertiary

Basement complex

Weathered or fractured deposits

FEET FEET

Figure 3. Generalized geologic sections across Bicycle Basin, Fort Irwin National Training Center, California: A, A–A’ and B, B–B’.
10 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Quaternary-Tertiary deposits surround and partially fill 

Bicycle Basin (figs. 2, 3); these deposits were divided into 

Quaternary-Tertiary older alluvium and lacustrine deposits 

(QToa and QTol, respectively) that overlie the Tertiary 

sedimentary deposits and underlie Quaternary older and 

younger deposits. The Quaternary-Tertiary deposits represent 

a transitional unit during the Pliocene to Pleistocene; the 

Quaternary deposits roughly represent the Pleistocene and 

Holocene (Yount and others, 1994; Schermer and others, 

1996). The Quaternary-Tertiary older alluvium (QToa) is 

generally coarse-grained interbedded sands and gravels, 

whereas Quaternary-Tertiary lacustrine deposits (QTol) are 

fine-grained sandy clays and silts. The Quaternary-Tertiary 

older alluvium (QToa) grades into lakebed clays (QTol) north 

and northwest of Bicycle Lake (dry) playa. A considerable 

amount of clay, interbedded with sands and gravels, was 

described at depths of 200–420 ft below land surface (bls) 

in geologic logs from wells in this area (14N/3E-23B1–3, 

14N/3E-14P1, 14N/3E-14P2, and 14N/3E-23G1). These 

wells are adjacent to and along a dry wash, where large-storm 

runoff drains to the playa. The presence of extensive clay 

layers indicates that the wash and lakebed clays most likely 

were north and northwest of the present playa historically. The 

Quaternary-Tertiary older alluvium (QToa) generally is more 

consolidated and slightly less permeable than the overlying 

Quaternary alluvium, but still yields moderate amounts of 

water.

Quaternary deposits overlie the Quaternary-Tertiary 

deposits; these deposits were divided into Quaternary 

older and younger deposits. Quaternary older (Pleistocene) 

deposits include older colluvial, eolian, wash, and alluvial 

fan deposits (Qoc, Qoe, Qow, and Qoa, respectively; Yount 

and others, 1994; Schermer and others, 1996); these deposits 

were grouped into undifferentiated older alluvium (Qoa) in 

this report. The Quaternary older alluvium (Qoa) consists 

of interbedded sand and gravel. The clasts in these deposits 

vary with nearby source rocks. Near the base of Tiefort 

Mountain, the older alluvium is coarse grained and derived 

primarily from quartzite and granite. The Quaternary older 

alluvium (Qoa) typically is cemented by calcite in its upper 

10–20 ft where exposed at the surface. The older alluvium 

generally is more consolidated and slightly less permeable 

than the overlying younger alluvium, but still yields moderate 

amounts of water. Quaternary younger (Holocene) deposits 

include younger colluvial, eolian, playa, wash, and alluvial fan 

deposits (Qyc, Qye, Qp, Qyw, and Qya, respectively; Yount 

and others, 1994; Schermer and others, 1996); these deposits 

were grouped into undifferentiated younger alluvium (Qya) 

and playa deposits (Qp). The younger alluvium (Qya) and 

playa deposits (Qp) overlie the older alluvium throughout the 

basin (figs. 2, 3) and are composed of unconsolidated sand 

and gravel with some pedogenic silt and clay. The Quaternary 

younger alluvium (Qya) is coarser grained near the base of 

the hills surrounding Bicycle Basin and becomes finer grained 

and better sorted toward the Bicycle Lake (dry) playa. The 

Quaternary younger alluvium (Qya) generally is less than 20 ft 

thick near the margins of the valley and is generally thicker 

in the alluvial fans at the foot of Tiefort Mountain, but could 

be as thick as 130 ft in the central part of the basin (fig. 3A, 

B). The Quaternary younger alluvium (Qya) generally lies 

above the water table; however, it is more permeable than the 

underlying deposits and, if saturated, is capable of yielding 

large quantities of water to wells.

Quaternary playa deposits (Qp; fig. 2) form the surface of 

Bicycle Lake (dry) in the southeastern part of the basin. These 

deposits consist of moderately to well-sorted clay, silt, and 

fine sand and could be as much as 50 ft thick. These deposits 

interfinger with the surrounding Quaternary younger alluvium 

(Qya) and generally lie above the water table. Because these 

deposits are fine grained and much less permeable than the 

Quaternary younger alluvium (Qya), they tend to impede 

infiltration of surface water that ponds on the playa after 

occasional storms.

Structure and Depth to the Basement Complex

Gravity, seismic-refraction, and TEM data were collected 

for this study to help understand the three-dimensional 

structure and estimate the depth and shape of the Bicycle 

Basin. A gravity survey was used to understand the threedimensional structure and estimate the depth to the granitic 

basement (thickness of basin fill) in the study area. Data 

originally were collected in 1999 for only Bicycle Basin; 

additional data were collected NTC wide in 2010 (Jachens and 

Langenheim, 2014). The original gravity survey covers about 

15 mi2 and includes measurements at 350 gravity stations 

(R.C. Jachens, written commun., 2000). Estimating the depth 

to the basement complex using a gravity survey requires 

knowledge of the residual gravity field of the exposed geology 

and knowledge of the vertical density variation in the basin 

deposits. Data from boreholes that penetrate the surface of the 

basement complex and geophysical data, including seismic 

refraction (David Berger, U.S. Geological Survey, written 

commun., 1996) and TEM data (Burgess and Bedrosian, 

2014), were used to provide constraints on the thickness of the 

basin fill. For detailed information regarding how gravity data 

were analyzed, see Jachens and Langenheim (2014). 

The estimated altitude of the basement complex in the 

Bicycle Basin, based on gravity data, showed that the deepest 

part of the basin is north of Bicycle Lake (dry) playa near 

monitoring wells 14N/3E-13M2–4, at an altitude below 0 

ft relative to NAVD 88 (or about 2,300 ft bls; fig. 4). To the 

north, the basin appears to become shallower over a short 

lateral distance, indicating the existence of one or more 

unnamed east–west trending faults. To the southwest, the basin 

also becomes shallower, but more gradually than to the north.
Geohydrologic Framework 11

sac11-0424_fig 04

BL4

BL3

BL2

BL1

26K1,3,4

18N1 18N2

35C4

35C3

35C1,2

28H2

28A1

27E2

27E3

27E1

24Q1–5

24H1 23G1

23B1–3

22P1

22N1,2

14P2 14P1

14H1 13M2–4

13M1

13K1

EXPLANATION

23G1

23B1–3

22P1

14P1

Bicycle groundwater basin Well type and identifier (see table 1)

Section A–A’

Section B–B’

Seismic line and identifier

Township/range

Faults

Bicycle model inferred faults

Altitude of basement, in feet

 above NAVD 88. Contour 

 interval is 200 feet.

TEM array and identifier

Jachens and Langenheim,

 2014

Gravity station 

BL2

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

North Bicycle Lake fault

Tiefort Mountain fault

Coyote Canyon fault zone

R. 3 E. R. 4 E.

T.

14

N.

A

A’

B

B’

2,600

2,400

2,400

2,400

2,200

2,200

2,200

2,200

2,000

2,000

2,000

1,800

1,800

1,600

0

0

200

200

400

400

600

600 800

 1,000

 1,200

800

1,000

1,000

1,000

800

1,200

1,200

1,400

1,400

1,600

2,200

2,400

South Coyote Canyon fault

Unnamed fault 2

Base modified from U.S. Geological Survey and other Federal digital data, 

various scales; Universal Transverse Mercator, zone 11; North American 

Datum of 1983; North American Vertical Datum of 1988 (NAVD 88)

1

2

3

4

1

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Unnamed fault 1

1,600

24H1

Figure 4. Altitude of the basement complex, wells, transient electromagnetic survey (TEM) locations, and location of seismic lines in 

Bicycle Basin, Fort Irwin National Training Center, California.
12 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The altitude of the basement complex estimated from 

gravity data also was compared with the altitudes estimated 

from the seismic-refraction data collected in four locations and 

from the TEM data at four soundings in the basin (fig. 4). The 

seismic-refraction method uses a seismic source to generate 

compression-wave energy (P-waves) and a seismograph to 

measure and collect the timing of the first arrival of a refracted 

wave at an array of geophones. Different geologic layers 

typically have different refracted wave velocities. These 

velocity differences are used to determine the depth to the 

refracting layer in the subsurface. Transient electromagnetic 

surveys, or TEM, are a technique that provides a measure of 

subsurface resistivity by passing a current through a wire loop, 

which, as explained by Ampere’s law, generates a primary 

magnetic field. The primary current is turned off rapidly, 

thereby causing a time-varying change in magnetic flux, which 

induces voltages and, hence, eddy currents in conductive 

bodies according to Faraday’s law. In TEM, a secondary 

magnetic field is produced by the decay of these subsurface 

eddy currents, and the time derivative of this secondary 

magnetic field commonly is measured as a voltage with time 

after primary current turnoff at one or more surface receivers. 

An apparent resistivity is calculated from the measured 

voltage at the receiver coil and the time elapsed after turnoff 

(Fitterman and Labson, 2005).

With the exception of the southwestern seismic line 

(fig. 4, line 2), the estimated bedrock-surface altitudes from 

three of the four seismic lines agreed well with the estimated 

altitude based on the gravity data. The northern seismic lines 

(fig. 4, lines 3, 4) crossed two topographic divides between 

granitic outcrops to evaluate subsurface structure across 

potential groundwater-flow boundaries. The seismic data 

indicated that a buried valley in the bedrock surface exists 

beneath the western section (fig. 4, line 4) that connects areas 

of thicker sediments overlying bedrock to the northeast and 

southwest. Such a buried valley through a bedrock ridge could 

allow increased subsurface flow between deeper portions 

of the basin if there is a head gradient between them. The 

southwestern seismic line (fig. 4, line 2) was collected in 

the area of the projected trace of one or more faults through 

the basin to evaluate the possible location of the faults. The 

estimated altitude of the basement complex, based on the 

seismic data, ranged from 1,450 to 1,280 ft above NAVD 88 

(or a depth of 920–1,100 ft bls) from southwest to northeast. 

The estimated altitudes based on seismic data were about 

350–620 ft shallower than the estimate of 1,100–650 ft based 

on the gravity data; the apparent discrepancy could reflect the 

presence of volcanic or conglomerate bedrock that has a less 

pronounced density contrast, affecting the interpreted depth 

to bedrock from gravity data. The seismic data also suggested 

that projected fault traces cross the basin in a stepwise manner 

near this line. 

Results from the TEM surveys were used to refine the 

depth-to-basement estimates in the southwestern part of the 

basin. The modeled apparent resistivity from these surveys 

also supported the shallowing of basement to the southwest, 

although the depths were as much as several hundred feet 

shallower than estimated using gravity data. The altitude of 

the basement complex was estimated using various densitydepth functions in the gravity inversion equation. Changes in 

this density function or rock type can result in shallower or 

deeper estimates of depth to basement, which is why estimates 

from these methods do not agree exactly. In any case, the 

interpreted overall shape of the basin was consistent.

Faults

Faults play a large role in the physiography of Fort Irwin 

and control the shape of Bicycle Basin (Yount and others, 

1994; Morin, 2000). Many faults in Bicycle Basin have been 

active during the Quaternary although few have demonstrated 

Holocene rupture; none are considered a seismic risk (Miller 

and others, 1994). The sinistral faults that strike northwest and 

east can be shown to have last moved during the Quaternary, 

whereas thrust faults that strike northeast last moved before 

the Quaternary (fig. 2). Several faults have been mapped in the 

bedrock hills around Bicycle Basin; the most prominent ones 

are the Bicycle Lake and Coyote Canyon fault zones (Yount 

and others, 1994; Schermer and others, 1996; Miller and 

Yount, 2002). The precise locations of these faults, or splays 

off the faults, where they cross Bicycle Basin and are buried 

by sediment, are uncertain. The locations of these buried 

faults were approximated by projecting mapped faults into the 

basin. Additionally, the location of mapped and other potential 

faults in Bicycle Basin were refined using data collected 

for this study, including geophysical and gravity surveys, 

groundwater-level measurements, and groundwater-flow 

model calibration. 

The Bicycle Lake fault zone is made up of east-trending 

faults that cross the southern part of the basin and form the 

southern boundary of the basin (fig. 2). The Bicycle Lake 

fault zone uplifts and offsets rocks of the basement complex 

between Bicycle Basin and Irwin Basin to the south. Uplift 

and offset across the Bicycle Lake fault zone prevents 

groundwater flow between Bicycle and Irwin Basins; this 

hypothesis is supported by differences in water level between 

the basins. One fault splay borders the southern edge of 

Bicycle Lake (dry) playa and lies just north of wells 14N/3E35C1–3 (fig. 2). This fault is referred to as the North Bicycle 

Lake fault by Yount and others (1994).

The Coyote Canyon fault zone is made up of eastwest trending faults that cross the northern part of the basin 

and form the northern boundary of the basin (fig. 2). Offset 

Quaternary-Tertiary sedimentary deposits and basement 

complex appear on the north side of the Coyote Canyon fault 

zone at the north end of Bicycle Basin. Either this offset or 

the fault itself could act as a barrier preventing groundwater 

flow at depth from the Granite Mountains in the north toward 

Bicycle Basin to the south. On the basis of data collected for 

this study, an east-west trending fault splay of the Coyote 

Canyon fault zone was projected to extend into Bicycle Basin, 

just south of wells 14N/3E-14H1 and 14N/3E-13M1–4, which 

is referred to as the South Coyote Canyon fault in this report. 
Geohydrologic Framework 13

Two additional faults were identified in Bicycle Basin 

based on water-level, geophysical- and gravity-survey data, 

and calibration of the groundwater-flow model. Unnamed 

fault 1 (fig. 2) trends northwest-southeast and is a projected 

continuation of mapped faults in bedrock areas to the southeast 

and northwest. Unnamed fault 1 was projected to cross 

Bicycle Lake (dry) playa approximately parallel to the crossrunway that bisects the main runway (fig. 4) and connects 

to the southernmost of two northwest–southeast trending 

parallel faults mapped near the southeastern edge of playa. 

It was unknown whether the northernmost of these parallel 

faults crosses the basin. One multiple-well monitoring site 

(14N/3E-26K1, 3, 4) was drilled south of the unnamed fault 

1 projection. Water-level altitudes measured in three wells 

at this site were about 6–20 ft higher than in wells (14N/3E24Q5 and 14N/3E-23B3, respectively) north of unnamed fault 

1. Unnamed fault 2 trends west-northwest–east-southeast and 

is a projected continuation of mapped faults in Tertiary older 

alluvium along the west side of the basin. Historical water 

levels in wells (14N/3E-22N1, 14N/3E-22P1, 14N/3E-27E2, 

14N/3E-28A1, and 14N/3E-28H2) south of unnamed fault 2 

were more than 40 ft higher than water levels in wells north 

of unnamed fault 2. Unfortunately, wells 14N/3E-22N1–2 and 

14N/3E-22P1 were destroyed in the late 1990s–early 2000, 

so more recent water levels were unavailable. Water levels 

in wells 14N/3E-28A1 and 14N/3E-27E3, near 14N/3E22N1–2, had risen slightly, however, probably as a result of 

water leaking from nearby infrastructure (from an overhead 

water pipe used to fill water tanks or from buried water pipes 

transferring water from Bicycle Basin to Irwin Basin). Depth 

to basement is shallow in well 14N/3E-22P1, indicating offset 

south of unnamed faults 1 and 2 similar to that observed 

south of North Bicycle Lake fault. These data indicated that 

unnamed faults 1 and 2 impede groundwater flow from the 

southern part of the basin to some extent.

Hydrologic Framework

The aquifer system in Bicycle Basin was delineated from 

information contained in previous studies and supplemented 

with geophysical investigations of the basin and with 

geohydrologic data collected from existing and newly installed 

wells in the basin. As part of this project, several multiplewell monitoring sites were installed to update and refine the 

understanding of the geohydrologic framework of Bicycle 

Basin. During 1993–2011, six multiple-well monitoring sites 

were drilled (table 1; fig. 2). Two piezometers each were 

installed at multiple-well monitoring sites BA1 (14N/3E22N1–2) and BLA1 (14N/3E-35C2–3) during 1993 and 1994, 

respectively. During 1997, three piezometers were installed 

at multiple-well monitoring site BLA2 (14N/3E-13M2–4), 

and five piezometers at BLA3 (14N/3E-24Q1–5). During 

2007, three piezometers were installed at a multiple-well 

monitoring site BLA4 (14N/3E-23B1–3). During 2011, three 

piezometers were installed at a multiple-well monitoring 

site BLA5 (14N/3E-26K1, 2, 4). A typical multiple-well 

monitoring site in Bicycle Basin consisted of two to five 

2-in.-diameter polyvinyl chloride (PVC) piezometers with 

20-ft screen intervals installed at different depths in the same 

borehole. The actual design of each multiple-well monitoring 

site was determined during well construction by examining 

the drill cuttings collected during drilling and the borehole 

geophysical logs. The lithologic logs of the drill cuttings and 

the geophysical logs from each borehole are presented in 

appendix 1, figures 1–1 through 1–6.

Aquifer System Definitions

The aquifer system in Bicycle Basin consists of two 

aquifers, referred to as the upper aquifer and lower aquifer 

in this report. The upper aquifer is generally unconfined and 

is composed of the saturated part of the younger Quaternary 

alluvium (Qya and Qp), the Quaternary older alluvium (Qoa), 

and the Quaternary-Tertiary older alluvium and lacustrine 

deposits (QToa and QTol). The saturated thickness of the 

upper aquifer was about 300 ft near well 14N/3E-23B1–3; it 

thins at the margins of the basin (fig. 3). The lower aquifer is 

composed of Tertiary younger sedimentary deposits (Tyg) and 

older sedimentary deposits (Tog) and generally is confined 

or partly confined. This aquifer is as much as 1,500 ft thick 

and generally is less permeable than the upper aquifer. The 

base of the aquifer system was considered to be the top of 

the basement complex, although the deepest part of the older 

Tertiary sedimentary deposits did not appear to produce 

much water. For this study, the areal extent of Bicycle Basin 

was based on the altitude where the basement complex is 

intersected by the 1965 groundwater-level altitude of about 

2,225 ft, which was estimated from water levels in wells 

14N/3E-13K1, -14H1, and -13M1, measured in 1955, 1964, 

and 1965, respectively. The resulting areal extent of Bicycle 

Basin used for this study differs somewhat in that it is smaller 

than that of previous studies (for example, Wilson F. So and 

Associates, 1989). 

Hydraulic conductivities for the upper aquifer were 

estimated from aquifer tests (table 2) and slug tests (Nawikas 

and others, written commun., 2011). Several aquifer tests 

were done at specified wells perforated solely in the upper 

aquifer in Bicycle Basin by C.F. Hostrup and Associates 

(1955), U.S. Army Corps of Engineers (written commun., 

1965), James M. Montgomery and Associates (1981), 

Wilson F. So and Associates (1989), and the U.S. Geological 

Survey (unpublished data, 1997, 2008; Nawikas, written 

commun., 2011). For wells that did not have aquifer tests, 

the transmissivities of the saturated interval of wells were 

approximated using the relation between specific capacity 

and transmissivity reported by Thomasson and others (1960). 

The specific capacity measured at wells in the basin ranged 

from about 6.4 to 22.5 gallons per minute per foot (gpm/ft) of 

drawdown. Specific capacities (in gpm/ft) were multiplied by 

230 (Thomasson and others, 1960) to yield transmissivities 

ranging from about 1,740 to 10,630 square feet per day (ft2

/d). 
14 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Transmissivities were divided by the estimated saturated 

thicknesses of the aquifer to yield hydraulic conductivities 

for the upper aquifer ranging from about 3 to 35 feet per day 

(ft/d). The hydraulic conductivity estimated from slug tests 

performed in monitoring well 14N/3E-26K4, perforated from 

250 to 270 ft bls in the upper aquifer (table 1), was 28 ft/d 

(Joseph Nawikas, U.S. Geological Survey, written commun., 

2011), which was within the previously estimated range.

Limited data about the hydraulic properties for the 

lower aquifer were available. The specific-capacity test in 

well 14N/4E-18N1, with perforations spanning from the 

Quaternary-Tertiary older alluvium (QToa) to Tertiary older 

gravels (Tog), should have reflected, at least partially, the 

properties of the lower aquifer; it showed the lowest hydraulic 

conductivity of any of the specific capacity tests at 3 ft/d 

(table 2). On the basis of grain size from lithologic cuttings 

and characteristics during drilling, age, and consolidation, the 

hydraulic properties for the lower aquifer were assumed to be 

low (1–5 ft/d). The horizontal hydraulic conductivity estimated 

from a slug test performed in monitoring well 14N/3E-26K1, 

perforated from 320 to 340 ft in a sand and gravel layer of 

the Tertiary younger gravels (Tyg) in the lower aquifer, was 

6.8 ft/d (Nawikas and others, U.S. Geological Survey, written 

commun., 2011). Vertical hydraulic conductivities were 

estimated by evaluating test results, analyzed by the USGS 

Hydrologic Research Laboratory in Sacramento for core 

samples collected from three depths (310–315 ft, 660–665 ft, 

and 860–865 ft) during the drilling of the borehole for wells 

14N/3E-23B1–3 (fig. 2, appendix fig. 1–3). The shallow 

Table 2. Summary of aquifer-test results from various studies in Bicycle Basin, Fort Irwin National Training Center, California, 

1955–2008.

[Location of wells shown in figure 2. Abbreviations: CoE, Corp of Engineers; ft, feet; ft/d, feet per day; ft2/d, feet squared per day; gpm/ft, gallons per minute 

per foot of drawdown; M, maximum drawdown; m, minimum drawdown; USGS, U.S. Geological Survey; *, average hydraulic conductivity shown, hydraulic 

conductivities estimated from specific depths in aquifer-test data archived at the USGS office; —, no data]

State well 

number

Local 

name

Date tested Tested by

Specific 

capacity 

(gpm/ft)

Transmissivity 

(ft2

/d)

Saturated 

thickness 

(ft)

Hydraulic 

conductivity 

(ft/d)

Drawdown

Specific 

yield 

(percent)

14N/3E-13K1S B-1 January 1955 Hostrup1 8.08 2

1,858 270 6.9 M* —

14N/3E-13K1S B-1 January 1955 Hostrup1 15.73 2

3,549 270 13.1 m* —

14N/3E-13K1S B-1 November 1978 Montgomery3 — — 270 — — 12.5

14N/3E-13M1S B-4 June 1965 CoE6 22.50 2

5,175 300 17.3 M* —

14N/3E-13M1S B-4 June 1965 CoE6 21.00 2

4,830 300 16.1 m* —

14N/3E-13M1S B-4 January 1988 So4 7.53 2,005 300 6.7 — —

14N/3E-13M1S B-4 September 1997 USGS5 — 10,630 300 35.4 — —

14N/3E-13M1S B-4 November 1978 Montgomery3 — — 330 — — 23.6

14N/3E-14H1S B-2 November 1964 CoE6 13.00 2

2,990 300 10.0 M* —

14N/3E-14H1S B-2 November 1964 CoE6 20.00 2

4,600 300 15.3 m* —

14N/3E-14H1S B-2 November 1978 Montgomery3 — 2,000 330 6.1 — 21.0

14N/3E-14P1S B-6 March 1988 So4 8.46 2,741 349 7.9 — —

14N/3E-14P2S TH-7 March 1988 So4 — 3,090 359 8.6 — —

14N/3E-14P2S TH-7 January 2008 USGS5 — 4,310 359 12.0 — —

14N/3E-22P1S B-3 November 1978 Montgomery2 — — — — — 5.0

14N/3E-24H1S BX-1 October 1980 Montgomery — — — — — 8.2

14N/4E-18N1S B-5 January 1988 So4 6.40 1,738 580 3.0 — —

14N/4E-18N2S B-5A January 2008 USGS5 — 7,500 580 12.9 — —

1

C.F. Hostrup and Associates, 1955.

2

Transmissivity calculated by multiplying specific capacity by 230 (Thomasson and others, 1960).

3

James M. Montgomery and Associates, 1981.

4

Wilson F. So and Associates, Inc., 1989.

5

U.S. Geological Survey, continuous water-level data collected during 2008–09; multiple dates were used to estimate transmissivity.

6

U.S. Army Corps of Engineers, wells drilled during 1964–65.
Geohydrologic Framework 15

core consisted of sandy, silty clay of the Quaternary-Tertiary 

lacustrine deposits (QTol) unit; the middle core consisted of 

sandy, silty clay of the Tertiary younger gravels (Tyg) unit; 

and the deep core consisted of fine-grained deposits of the 

Tertiary older gravels (Tog) unit. Analyses of the cores (Kevin 

Ellett, U.S. Geological Survey, written commun., 2008) 

indicated that vertical hydraulic conductivities varied and 

were 0.0009 ft/d for the shallow core (Quaternary-Tertiary 

lacustrine deposits, QTol), 0.01 ft/d for the middle core 

(Tertiary younger gravels, Tyg), and 0.0004 ft/d for the deeper 

core (Tertiary older gravels, Tog). These values were measured 

on low-volume samples, subsampled from cores that generally 

were less than 2 ft in length, and were likely not representative 

of hydraulic conductivities in the lower aquifer as a whole 

because of the heterogeneous nature of the deposits.

Natural Recharge and Discharge

Previous investigators estimated annual natural recharge 

to be low, ranging from negligible (James M. Montgomery 

and Associates, 1981) to more than 300 acre feet per 

year (acre-ft/yr) for the Bicycle Basin (Wilson F. So and 

Associates, 1989). As previously stated, annual precipitation 

in the region of Bicycle Basin is about 2–15 inches, and 

potential evapotranspiration is about 70 inches. Except during 

extended storms, recharge derived from direct precipitation is 

minimal. Natural recharge to the basin is only from infiltration 

of accumulated storm runoff, primarily in the winter or after 

short summer thunderstorms, along normally dry washes and 

near the base of the surrounding hills (fig. 1). Groundwater 

discharges from Bicycle Basin as groundwater underflow to 

the south, along the southeast side of the playa (fig. 2). 

Natural recharge in Bicycle Basin was assumed primarily 

to be from infiltration and underflow of precipitation runoff 

along the major washes that drain watersheds, including 

the upland area near Goldstone and the Granite Mountains 

to the west and north of Bicycle Basin (fig. 1). Additional 

groundwater recharges along smaller drainages in the 

northwestern and northeastern parts of the basin and at the 

base of Tiefort Mountains (fig. 2). Although surface runoff 

collects on the Bicycle Lake (dry) playa, recharge of this water 

on the playa was assumed to be negligible. After large storms, 

ponded water can remain on the playa for several months 

before evaporating because of the fine-grained texture and 

extremely low permeability of the playa deposits. Some water 

could recharge the aquifer system along the edge of the playa 

deposits where the sediment is coarser grained. 

A range of modeled estimates of natural recharge for 

Bicycle Basin from infiltration of runoff from precipitation 

and underflow was developed using the Basin Characterization 

Model (BCM; Flint and Flint 2007a, b). The BCM is a 

regional, physically based model of the southwestern United 

States that calculates monthly water-balance fractions and 

changes in soil moisture, runoff, and recharge on the basis 

of topography; vegetation density; soil composition, depth, 

and water storage; underlying bedrock geology; and spatially 

distributed transient values (measured or estimated) of air 

temperature, precipitation, and potential evapotranspiration 

(PET; Flint and Flint 2007a, b). The climate data used to 

drive the BCM are available as monthly gridded maps of 

precipitation and air temperature at a 2.5-mi (4-kilometer 

[km]) spatial resolution from PRISM (the empirically based 

Parameter-Elevation Regressions on Independent Slopes 

Model; Daly and others 2004). Because a finer resolution of 

BCM simulations was needed for this study, the data were 

downscaled to a 885-ft (270-meter [m]) spatial resolution 

following Flint and Flint (2007a). These data were compared 

to the nearby climate stations “Goldstone Echo 2”, “Daggett 

FAA Airport”, “Barstow Fire Station” and “Dunn Siding” 

(Western Regional Climate Center of the Desert Research 

Institute, WRCC-DRI, 2009, http://www.wrcc.dri.edu) and 

“San Bernardino–Barstow NE - #134” (California Irrigation 

Management Information System, 2009). The average 

monthly measured precipitation between 1948 and 2010 for 

stations near Bicycle Basin ranged from about 0.03 inches in 

June to about 1.2 inches in February. Figure 5A shows high 

variability in monthly precipitation for December through 

March for the five climate stations in the region, indicating 

the variability in winter storm patterns that track through the 

region. Except for sporadic tropical storms, precipitation in 

the warmer months was regionally distributed. Area-averaged 

minimum and maximum monthly temperatures ranged from 

about 34 to 60 °F in December and from about 70 °F to 

more than 103 °F in July. Temperature variability among 

the three climate stations was small (fig. 5B). Generally, the 

minimum and maximum temperatures at the Daggett FAA 

Airport station were slightly higher than those at the other two 

stations. Average monthly potential evapotranspiration rates 

ranged from about 2.0 in. for December to about 10.2 in. for 

June (fig. 5C). Results of the BCM simulations of runoff and 

recharge are described in the “Simulation of Natural Recharge 

and Discharge” section.

Groundwater discharges from Bicycle Basin by 

underflow through fractured volcanic material and granitic 

bedrock southeast of the Bicycle Lake (dry) playa. Discharge 

in this part of the basin was inferred because (1) long-term 

runoff and recharge into the basin were greater than zero, 

(2) there are no outflows from the basin other than subsurface 

flow in the southeast, and (3) the estimated predevelopment 

water level, as discussed in “Groundwater Altitudes and 

Movement” section, was higher than the estimated bedrock 

elevation at this point. Evaporative loss of groundwater from 

the Bicycle Lake (dry) playa was negligible because the depth 

to groundwater under predevelopment conditions was more 

than 30 ft bls. Prior to groundwater development in 1967, 

Bicycle Basin was considered to be in a steady-state condition, 

where discharge is equivalent to recharge to the basin with no 

appreciable change in storage.
16 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 05abc

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Average monthly total

precipitation, in inches 

A

0

20

40

60

80

100

120

Average monthly minimum

and maximum temperatures,

in degrees Fahrenheit

Daggett FAA Airport, California (042257) Daggett FAA Airport, California (042257)

Barstow Fire Station, California (040521) Barstow Fire Station, California (040521)

San Bernardino−Barstow Northeast - #134 San Bernardino−Barstow Northeast - #134

B

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Average monthly total potential

evapotranspiration, in inches 

San Bernardino-Barstow Northeast - #134

C

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Minimum temperature Maximum temperature

Goldstone Echo 2, California (043498)

Daggett FAA Airport, California (042257)

Barstow Fire Station, California (040521)

Dunn Siding, California (042570)

San Bernardino−Barstow Northeast - #134 

Western Regional Climate Center (WRCC) California Irrigation Management 

 Information System (CIMIS)

Month

Month

EXPLANATION

EXPLANATION

Month

EXPLANATION

This needs to be added to figure caption: Goldstone December 1, 1973, to July 31, 2006, (http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca3498); Daggett July 1, 1948, to December 31, 

2010, (http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca2257); Barstow Fire May 1, 1980, to December 31, 2010, (http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0521); Dunn Siding July 8, 

1959, to August 31, 1971, (http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca2570); San Bernardino-Barstow NE January 1, 1997, to May 31, 2011, (http://wwwcimis.water.ca.gov/cimis/frontMonthlyReport.do).

Figure 5. Comparisons of average monthly climate variables for the Fort Irwin National Training Center, San Bernardino County, 

California: A, average monthly total precipitation (1948–2010); B, minimum and maximum temperatures for three climate stations; and 

C, averaged monthly total potential evapotranspiration for one climate station. (Climate station data from Western Regional Climate 

Center or from the CIMIS; Goldstone December 1, 1973, to July 31, 2006; http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca3498; Daggett 

July 1, 1948, to December 31, 2010; http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca2257; Barstow Fire May 1, 1980, to December 31, 2010; 

http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0521; Dunn Siding July 8, 1959, to August 31, 1971; http://www.wrcc.dri.edu/cgi-bin/

cliMAIN.pl?ca2570; San Bernardino-Barstow NE January 1, 1997, to May 31, 2011; http://wwwcimis.water.ca.gov/WSNReportCriteria.

aspx).
Geohydrologic Framework 17

Groundwater Pumping and Water Use

Groundwater development in Bicycle Basin began in 

1955 when production well 14N/3E-13K1 (fig. 2) was drilled 

although pumping did not begin until 1967. Production 

wells 14N/3E-14H1 and 14N/3E-13M1 were drilled in 1964 

and 1965, respectively. Production well 14N/4E-18N1 was 

drilled in 1983, and well 14N/3E-14P1 was drilled in 1988. 

Groundwater pumped from Bicycle Basin is transported (by 

buried pipeline) to Irwin Basin, where it is blended with the 

water pumped from Irwin and Langford Basins. With the 

exception of ponded water at a standpipe used to fill water 

trucks in the southwestern part of the basin, none of the water 

that is pumped from Bicycle Basin is used in or returned to 

the basin.

Between January 1967 and December 2010, an average 

of about 1,050 acre-ft/yr of water was pumped from Bicycle 

Basin (table 3). Total pumpage during this period was about 

46,000 acre-feet (acre-ft). Pumpage records included annual 

basin pumpage (not by well) for 1967–83, annual pumpage 

by well for 1984–90 (fig. 6A), and monthly pumpage by well 

for 1990–2010 (fig. 6B). Average annual pumping rates were 

estimated from the number of years for which there were 

pumpage records from individual wells. Based on this, average 

annual pumpage was 294, 95, 212, 488, and 751 acre-ft/yr 

for production wells 14N/3E-13K1, 14N/3E-14H1, 14N/3E13M1, 14N/4E-18N1, and 14N/3E-14P1, respectively 

(table 3). Wells 14N/3E-13K1 and 14N/3E-14H1 ceased 

pumping during 2006 and 1994, respectively; these wells have 

since been destroyed. Well 14N/3E-13M1 ceased pumping 

during 2005, after which the well was rehabilitated; pumping 

resumed in 2009. Annual groundwater pumpage in the basin 

ranged from about 125 acre-ft in 1977 to 2,145 acre-ft in 1998; 

pumpage in 2010 was 1,090 acre-ft. Reported average monthly 

(1991–2010) pumpage in Bicycle Basin ranged from about 

65 acre-ft in February to about 165 acre-ft in August (table 4). 

Average monthly pumpage in the basin for January 1991 to 

December 2000 ranged from about 40 acre-ft for February to 

about 180 acre-ft for July (table 4). Average monthly pumpage 

during January 2001–December 2010 ranged from about 

85 acre-ft for February to about 155 acre-ft for September. 

Differences in average monthly pumpage between 1991–2000 

and 2001–10 indicated that pumping management practices 

changed over time. For 2001–10 compared to 1991–2000, 

average monthly pumpage increased 4–65 acre-ft during 

the months of September through May, but decreased by 

5–36 acre-ft during the months of June–August. This change 

in pumpage could be due to an increase in personnel and 

activities at the facility during the winter months and the 

extended block leave (break in rotational training) during June 

and July.

Groundwater Altitudes and Movement

Prior to groundwater development in Bicycle Basin, 

the groundwater gradient in the basin was relatively flat, 

with a slight gradient from the recharge sources toward the 

Bicycle Lake (dry) playa, where there was likely a subsurface 

outlet near the southeast end. This was inferred from the low 

recharge rate, no surface expression of discharge (such as a 

spring), and a water table too low (based on predevelopment 

water levels described earlier) to allow for discharge from the 

playa. Natural discharge was inferred at the southeast end, 

because the predevelopment water levels were higher than 

the basement only in this location along the basin boundary. 

Groundwater-level altitudes for the earliest (1955–97) and 

more recent (2010–11) measurements are shown in figure 7A

and B, respectively; these are altitudes for the shallowest 

well in multiple-well monitoring sites, the test wells, and the 

production wells. The water-table altitude was about 2,225 

ft above NAVD 88 at the time the first well was drilled in 

1955 (Kunkel and Riley, 1959). By 2010, the groundwaterlevel altitude ranged from about 2,130 ft in the northern part 

of the basin to 2,170 ft near Bicycle Lake (dry) playa. The 

interpreted direction of groundwater flow from the fall of 

2010 to winter of 2011 was from south-southwest to northnortheast, reflecting groundwater flow toward production 

wells in the northern part of the basin (fig. 7B). Water-level 

measurements for the period of record, 1955–2015, are 

presented in appendix 2. These data are in the USGS National 

Water Information System (NWIS) database and may be 

accessed at http://waterdata.usgs.gov/ca/nwis/.

Groundwater levels in Bicycle Basin declined in response 

to pumping, with relatively large declines near areas of larger 

withdrawals. Hydrographs in figure 8 show groundwater-level 

changes in selected wells in Bicycle Basin. These hydrographs 

indicate that water levels in the northeastern part of the 

basin declined as much as 100 ft in production well 14N/3E13K1 since the 1960s and as much as 75 ft in production 

well 14N/4E-18N1 and test well 14N/4E-18N2 since 1990 

(fig. 8A1). Groundwater levels in production wells 14N/3E13M1 and 14N/3E-14H1 (fig. 8A2) in the northwestern part 

of the basin declined about 90 ft from the 1960s through 

the early 1990s, when water levels stabilized as a result of 

reduced pumpage in these wells; these wells are north of the 

South Coyote Canyon fault. Likewise, groundwater levels 

in production well 14N/3E-14P1 and test well 14N/3E-14P2 

(fig. 8A3) in the western part of the basin, south of the South 

Coyote Canyon fault, declined about 100 ft since the 1980s. 

Groundwater levels declined more slowly near the Bicycle 

Lake playa, with about 40-ft declines in well 14N/3E-24H1 

(northeast of Bicycle Lake playa) during 1980–96 and in 

well 14N/3E-23G1 (northwest of Bicycle Lake playa) during 

1996–2010 (fig. 8A4).

Since 1993, water levels were measured sporadically 

in six multiple-well monitoring sites in Bicycle Basin 

(appendix 2; locations shown on fig. 2). Multiple-well 

monitoring sites 14N/3E-24Q1–5, 14N/3E-13M2–4, and 

14N/3E-23B1–3 have three to five 2-in.-diameter monitoring 

wells, each with a discrete perforated interval at various depths 

in the aquifer (table 1). 
18 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 06ab Pumpage, in acre-feet

2000

0

50

100

150

200

250

300

350

400

2010200920082007200620052004200320022001 2011

EXPLANATION

0

1965 1970 1975 1980 1985 1990 1995 2000 2005

500

1,000

1,500

2,000

2,500

3,000

Annual pumpage, in acre-feet

Year

A

Monthly pumping values shown in part B

B

14N/3E-13K1S; screened interval is

 2,226–1,826 feet above NAVD 88

14N/3E-14H1S; screened interval is

 2,194–1,839 feet above NAVD 88

14N/3E-13M1S; screened interval is

 2,194–1,826 feet above NAVD 88

14N/4E-18N1S; screened interval is

 2,089–1,609 feet above NAVD 88

14N/3E-14P1S; screened interval is

 2,013–1,868 feet above NAVD 88

1990 199919981997199619951994199319921991

Annual totals (Only annual pumpage

 data by basin are available through

 1983; see table 3 for sources of data) 

Figure 6. Pumpage by production well, for Bicycle Basin, Fort Irwin National Training Center, California: A, annual, 1967 to 2008, and 

B, monthly, 1990 to 2010. Location of wells shown on figure 2.
Geohydrologic Framework 19

Table 3. Annual pumpage, in acre-feet, for Bicycle Basin at Fort Irwin National Training Center, California, 1967–2010.

[Location of wells shown on figure 2.]

Year Annual

total

14N/3E-13K1S

B-1

14N/3E-14H1S

B-2

14N/3E-13M1S

B-4

14N/4E-18N1S

B-5

14N/3E-14P1S

B-6

1967 1

821 2307 2252 2263 0 0

1968 1

819 2306 2251 2262 0 0

1969 1

953 2356 2292 2305 0 0

1970 1

895 2335 2274 2286 0 0

1971 1

608 2227 2186 2194 0 0

1972 1

480 2179 2147 2153 0 0

1973 1

157 259 248 250 0 0

1974 1

170 264 252 254 0 0

1975 1

210 278 264 267 0 0

1976 1

393 2147 2120 2126 0 0

1977 1

123 246 238 239 0 0

1978 1493 2184 2151 2158 0 0

1979 1

462 2173 2141 2148 0 0

1980 1

865 2324 2265 2277 0 0

1981 1

792 2296 2243 2253 0 0

1982 1

757 2283 2232 2242 0 0

1983 1

865 2324 2265 2277 0 0

1984 689 201 153 90 245 0

1985 1,243 289 317 196 441 0

1986 1,329 231 135 384 578 0

1987 822 0 0 400 423 0

1988 1,032 195 29 411 398 0

1989 829 237 101 108 384 0

1990 1,312 357 99 298 558 0

1991 1,380 380 87 368 544 0

1992 1,135 353 4 282 495 0

1993 757 206 12 171 369 0

1994 961 272 19 170 500 0

1995 1,047 358 0 127 563 0

1996 1,222 373 0 194 654 0

1997 1,524 81 0 359 301 783

1998 2,143 188 0 230 621 1,104

1999 1,814 191 0 285 627 711

2000 1,904 24 0 171 627 1,082

2001 1,896 129 0 312 540 915

2002 1,984 407 0 252 808 516

2003 1,948 553 0 41 845 509

2004 1,938 583 0 18 523 813

2005 1,541 631 0 35 18 857

2006 1,275 229 0 0 166 880

2007 1,360 0 0 0 655 705

2008 868 0 0 0 384 484
20 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Year Annual

total

14N/3E-13K1S

B-1

14N/3E-14H1S

B-2

14N/3E-13M1S

B-4

14N/4E-18N1S

B-5

14N/3E-14P1S

B-6

2009 1,180 0 0 81 493 607

2010 1,090 0 0 116 424 551

Total pumpage 4

46,088 6,470 955 5,098 13,184 10,516

Number of years with reported pumpage 44 22 10 24 27 14

Average per year3 1,047 294 95 212 488 751

1

Distribution of pumpage by well was not available from historical data. Only total pumpage had been reported. Data for 1967–71 and 1973–79 were from 

James M. Montgomery and Associates, 1981; data for 1972 and 1980 were estimated by the U.S. Geological Survey; 1981–83 were from Wilson F. So and 

Associates, 1989; and 1984–2010 were from U.S. Army, Fort Irwin Directorate of Public Works.

2

Estimated distribution of pumpage by well based on averaged ratios of well pumpage to total pumpage for three years of recorded pumpage, 1984–86.

3

Average for each well was estimated based on only the number of years with reported pumpage from 1984 to 2010. Average of total annual pumpage was 

calculated for 44 years of reported pumpage. Because of rounding of numbers, calculation of total pumpage from averages and years reported may not equal 

total pumpage.

4

Total annual pumpage includes total pumpage for 1967–84 that was not available by well.

Table 3. Annual pumpage, in acre-feet, for Bicycle Basin at Fort Irwin National Training Center, California, 1967–2010.—Continued

[Location of wells shown on figure 2.]

Table 4. Comparison of minimum, maximum and average monthly pumpage, in acre-feet, for Bicycle Basin, Fort Irwin National Training 

Center, California, 1991 to 2010.

Month

1991–2010 1991–2000 2001–2010 Difference in 

average monthly 

pumpage Average Minimum Maximum Average Minimum Maximum Average

January 82.2 5.3 158.7 57.8 20.0 155.6 100.5 42.7

February 65.4 0.0 148.2 42.1 1.4 141.2 84.6 42.6

March 95.4 0.0 183.2 58.9 25.2 186.3 123.4 64.5

April 109.4 0.0 182.6 100.5 12.5 185.3 111.8 11.3

May 132.3 41.0 188.1 125.2 60.0 192.4 133.9 8.8

June 150.0 44.9 222.6 151.2 74.3 183.0 146.2 -5.0

July 160.8 128.9 209.4 177.2 64.9 201.9 141.6 –35.6

August 163.2 116.8 273.4 172.6 71.4 205.5 153.1 –19.6

September 147.7 83.0 206.8 140.6 48.9 207.5 155.7 15.1

October 137.2 51.7 212.2 134.4 57.2 219.8 138.5 4.0

November 102.7 9.7 174.3 85.5 9.9 179.7 116.0 30.5

December 95.4 18.2 169.0 83.6 6.1 151.3 102.7 19.1
Geohydrologic Framework 21

sac11-0415_fig 07a

A’

B

B

Unnamed fault 2

A

22P1

1/26/1993

2,243

23G1

10/30/1980

2,205

24H1

10/30/1980

2,219

14P2

1/30/1988

2,213

14P1

3/1/1988

2,204

18N2

12/3/1992

2,170

13K1

2/1/1955

2,227

18N1

1/26/1993

2,188

13M1

6/30/1965

2,216

23B3

na

14H1

11/14/1964 

2,221

35C1

4/10/1963

2,225

24Q5

7/14/1997

2,185

28H2

9/24/1993

2,329

28A1

9/24/1993

2,327 27E3

5/19/1993

 2,325

22N1

1/26/1994

2,247

13M4

7/9/1997

2,219

35C2

7/28/1994

2,208

26K3

na

Coyote Canyon fault zone

Tiefort Mountain fault

North Bicycle Lake fault

Unnamed fault 1

South Coyote Canyon fault

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

EXPLANATION

R. 3 E. R. 4 E.

T.

14

N.

A

A’

B’

Base modified from U.S. Geological Survey and other Federal digital data, 

various scales; Universal Transverse Mercator, zone 11; North American 

Datum of 1983; North American Vertical Datum of 1988 (NAVD 88)

Bicycle groundwater basin

Section A–A’

Section B–B’

Fault

Model inferred fault

Township/range

Well type and stacked identifier (see table 1)—top number is the well identifier; middle number 

 is date of earliest measurement (mm/dd/yyyy, mm=month; dd=day; yyyy=year); bottom number 

 is altitude of water table in feet above NAVD 88

14P1

3/1/1988

2,204

24Q5

7/14/1997

2,185

14P2

1/30/1988

2,213

24H1

10/30/1980

2,219

22P1

1/26/1993

2,243

Production Destroyed

Test well Obstructed

Multiple-well

 monitoring site

Figure 7. Water levels measured at production wells, test wells, and shallowest wells at multiple-well monitoring sites, Bicycle Basin, 

Fort Irwin National Training Center, California: A, earliest, 1955–97, and B, 2010–11.
22 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 7. —Continued

sac11-0424_fig 07b

?

?

?

?

?

? ?

?

?

?

B

North Bicycle Lake fault

Tiefort Mountain fault

Coyote Canyon fault zone

A

B

2,140

2,130

South Coyote Canyon fault

Unnamed fault 1

Unnamed fault 2

2,160

2,170

2,150

2,140

2,130

2,120

A’

B’

0 0.5 1 MILE

0 0.5 1 KILOMETER

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital data, 

various scales; Universal Transverse Mercator, zone 11; North American 

Datum of 1983; North American Vertical Datum of 1988 (NAVD 88)

EXPLANATION

Well type and stacked identifier (see table 1)—top number is the well identifier; middle number 

 is date of earliest measurement (mm/dd/yyyy, mm=month; dd=day; yyyy=year); bottom number 

 is altitude of water table in feet above NAVD 88

14P1

3/1/1988

2,204

24Q5

7/14/1997

2,185

14P2

1/30/1988

2,213

Production Multiple-well Test well

 monitoring site

116°40’ 116°38’ 116°36’

35°18’ 35°16’

Bicycle groundwater

 basin

Section A–A’

Section B–B’

Fault

Model inferred 

 fault

Line of equal water level,

 2010. Contour interval is

 10 feet.

Township/range

Direction of groundwater

 flow

23G1

12/14/2010

2,172

14P2

12/12/2010

2,111

13M1

12/13/2010

2,123

24Q5

12/17/2010

28A1 2,155

12/10/2010

2,337

27E3

5/14/2010

 2,328

13M4

12/13/2010

2,123 18N2

12/13/2010

2,125

26K3

4/25/2011

2,161

23B3

12/14/2010

2,141
Geohydrologic Framework 23

sac11-0424_fig 08a

2

Water-surface altitude, in feet above North American

Vertical Datum of 1988 (NAVD 88)

Year

1

A

3

4

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

14N/3E-13K1S—Screened interval 

 2,226−1,826 feet above NAVD 88

14N/4E-18N1S—Screened interval 

 2,089−1,609 feet above NAVD 88

14N/4E-18N2S—Screened interval 

 2,087−2,084 feet above NAVD 88

14N/3E-14H1S—Screened interval 

 2,194−1,839 feet above NAVD 88

14N/3E-13M1S—Screened interval 

 2,194−1,826 feet above NAVD 88

14N/3E-14P1S—Screened interval

 2,013−1,868 feet above NAVD 88

14N/3E-14P2S—Screened interval 

 2,013−1,868 feet above NAVD 88

14N/3E-24H1S—Screened interval 

 2,187−1,968 feet above NAVD 88

14N/3E-23G1S—Screened interval 

 2,179−1,620 feet above NAVD 88

Figure 8. Water-surface altitude in production and monitoring wells in Bicycle Basin, Fort Irwin National Training Center, California: 

A, periodic, 1963–2010, and B, continuous, 2007–10.
24 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 08a continued

Year

7

5

6

8

Water-surface altitude, in feet above North American

Vertical Datum of 1988 (NAVD 88)

A

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

2,050

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

2,100

2,150

2,200

2,250

14N/3E-24Q5S—Screened interval 2,046−

 2,035 feet above NAVD 88

14N/3E-24Q4S—Screened interval 1,915−

 1,895 feet above NAVD 88

14N/3E-24Q3S—Screened interval 1,755−

 1,735 feet above NAVD 88

14N/3E-24Q2S—Screened interval 1,620−

 1,600 feet above NAVD 88

14N/3E-24Q1S—Screened interval 1,467−

 1,447 feet above NAVD 88

EXPLANATION

14N/3E-13M4S—Screened interval 

 2,104−2,084 feet above NAVD 88

14N/3E-13M3S—Screened interval 

 1,994−1,974 feet above NAVD 88

14N/3E-13M2S—Screened interval 

 1,833−1,813 feet above NAVD 88

14N/3E-23B3S—Screened interval 

 2,122−2,102 feet above NAVD 88

14N/3E-23B2S—Screened interval 

 1,942−1,922 feet above NAVD 88

14N/3E-23B1S—Screened interval 

 1,672−1,652 feet above NAVD 88

14N/3E-22P1S—Screened interval 

 unknown 

14N/3E-22N1S—Screened interval 

 2,078−2,158 feet above NAVD 88

14N/3E-28A1S—Screened interval 

 unknown 

Figure 8. —Continued
Geohydrologic Framework 25

sac11-0424_fig 08b

2,150

2,152

2,154

2,156

2,158

2,160

2,162

2,164

2,166

14N/3E-24Q5S—Screened 

 interval 2,046−2,035 feet 

 above NAVD 88

14N/3E-24Q4S—Screened 

 interval1,915−1,895 feet 

 above NAVD 88

14N/3E-24Q3S—Screened 

 interval 1,755−1,735 feet 

 above NAVD 88

14N/3E-24Q2S—Screened 

 interval 1,620−1,600 feet 

 above NAVD 88

14N/3E-24Q1S—Screened 

 interval 1,467−1,447 feet 

 above NAVD 88

Measured value for

 14N/3E-24Q4S

Measured value for

 14N/3E-23B2S

2

Water-surface altitude, in feet above North American Vertical Datum of 1988 (NAVD 88) B

2,100

2,110

2,120

2,130

2,140

2,150

2,160

14N/3E-23B3S—Screened

 interval 2,122−2,102 feet 

 above NAVD 88

14N/3E-23B2S—Screened

 interval 1,942−1,922 feet 

 above NAVD 88

14N/3E-23B1S—Screened

 interval 1,672−1,652 feet 

 above NAVD 88

3

2,080

2,100

2,120

2,140

2,160

2,180

2,200 14N/3E-23G1S—Screened

 interval 2,179−1,620 feet 

 above NAVD 88

14N/4E-18N2S—Screened

 interval 2,087−2,084 feet 

 above NAVD 88

14N/3E-14P2S—Screened

 interval 2,013−1,868 feet 

 above NAVD 88

Measured value for

 14N/4E-18N2S

 

Measured value for

 14N/3E-14P2S

 

4

Dec.

2007

Dec.

2008

June

2008

Dec.

2009

June

2009

Dec.

2010

June

2010

Dec.

2007

Dec.

2008

June

2008

Dec.

2009

June

2009

Dec.

2010

June

2010

Dec.

2007

Dec.

2008

June

2008

Dec.

2009

June

2009

Month and year

Dec.

2010

June

2010

14N/3E-13M4S—Screened 

 interval 2,104−2,084 feet 

 above NAVD 88

14N/3E-13M3S—Screened 

 interval 1,994−1,974 feet 

 above NAVD 88

14N/3E-13M2S—Screened

interval 1,833−1,813 feet 

 above NAVD 88

Measured value for

 14N/3E-13M2S

2,100

2,110

2,120

2,130

2,140

1

EXPLANATION

Dec.

2007

Dec.

2008

June

2008

Dec.

2009

June

2009

Dec.

2010

June

2010

Figure 8. —Continued
26 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Water levels in wells 14N/3E-24Q1–5 (fig. 8A5) showed 

a similar long-term water-level decline as those in test hole 

14N/4E-18N2, used as a proxy for water levels in production 

well 14N/4E-18N1 (fig. 8A1). Monitoring well site 14N/3E24Q1–5 is along the southeastern edge of Bicycle Lake (dry), 

south of wells 14N/4E-18N1, -18N2 and 14N/3E-24H1, and 

east of wells 14N/3E-14P1 and -14P2. Wells 14N/3E-24Q1–5, 

14N/4E-18N1 and -18N2, are perforated in QuaternaryTertiary older alluvium, Tertiary younger gravels, and 

Tertiary older gravels (QToa, Tyg, and Tog). Water levels in 

wells 14N/3E-24Q1–5 were also similar to, but consistently 

higher than, water levels in well 14N/3E-24H1, perforated 

in Quaternary older alluvium (Qoa) and Quaternary-Tertiary 

older alluvium (QToa). During the late-1990s, water levels 

in wells 14N/3E-24Q1–5 (fig. 8A5) were lower than those in 

production well 14N/3E-14P1 and nearby test well 14N/3E14P2 (fig. 8A3), to the west, but by 2007–09, water levels in 

wells 14N/3E-24Q1–5 were higher than water levels in well 

14N/3E-14P1 and -14P2, indicating a shift in groundwaterflow directions as a result of pumping in well 14N/3E-14P1. A 

seasonal trend was also observed in the continuous water-level 

data (fig. 8B1), described later in this section.

Water levels in wells 14N/3E-13M2–4 (fig. 8A6), near 

production well 14N/3E-13M1 in the northern part of the 

basin, showed long-term trends similar to water levels in the 

production well (fig. 8A2). Water levels in the shallower wells 

14N/3E-13M3 and 14N/3E-13M4, perforated in QuaternaryTertiary older alluvium (QToa), were similar to those in the 

production well 14N/3E-13M1, perforated in the QuaternaryTertiary older alluvium and Tertiary younger gravels (QToa 

and Tyg); whereas, water levels were lower in the deeper well 

14N/3E-13M2, perforated in Tertiary younger gravels (Tyg). 

Occasional steep water-level declines in well 14N/3E-13M2 

reflected water levels when production well 14N/3E-13M1 

was pumping, indicating less groundwater flow from the 

Tertiary younger gravels (Tyg) to the production well. These 

wells also showed a seasonal trend in the continuous waterlevel data (fig. 8B2).

Wells 14N/3E-23B1–3 are in the center of the basin near 

production well 14N/3E-14P1 and adjacent test well 14N/3E14P2; water levels in these wells (fig. 8A7) showed a similar 

decline as in test well 14N/3E-14P2, used as a proxy for the 

production well 14N/3E-14P1 (fig. 8A3). Water levels in the 

middle well, 14N/3E-23B2, perforated in the main production 

zone, mimicked water levels measured in wells 14N/3E14P1 and -14P2 (fig. 8A3). Declines in water levels in the 

deep well, 14N/3E-23B1, were damped slightly, indicating 

less groundwater flow from the lower aquifer and Tertiary 

units to the production well. Water levels in the shallowest 

well, 14N/3E-23B3, showed very little seasonal change and 

declined slightly in response to pumping in well 14N/3E-14P1. 

At wells 14N/3E-23B1–3, the vertical gradients indicating 

downward and upward flow toward the production zone were 

likely a response to nearby pumping in 14N/3E-14P1.

Water levels in well 14N/3E-22P1 (fig. 8A8) showed a 

slight decline from 1993 to 1997, while water levels in wells 

14N/3E-22N1 and 14N/3E-28A1, south-southwest of well 

14N/3E-22P1, showed minimal or no water-level decline. This 

indicated that these wells were isolated from pumping in other 

parts of the basin by faults acting as barriers to groundwater 

flow or differences in lithology not related to faulting. 

Continuous water-level data from multiple-well 

monitoring sites indicated that the water levels varied 

with depth in some areas, primarily showing groundwater 

moving from relatively shallow and deep parts of the aquifer 

to the zones in between, from which groundwater was 

withdrawn (figs. 2, 8B). Hourly water levels were collected 

from December 2007 through December 2010. To simplify, 

continuous water-level data were filtered to show only the 

noon (12 p.m.) and midnight (12 a.m.) values (figs. 8B1–4). 

Water levels in well 14N/3E-13M4 were lower than those in 

well 14N/3E-13M3, which were usually higher than water 

levels in well 14N/3E-13M2 (fig. 8B2). These water levels 

showed slight upward vertical flow between wells 14N/3E13M4 and 14N/3E-13M3 and downward vertical flow between 

wells 14N/3E-13M3 and 14N/3E-13M2.

The water-level differences between the shallow 

wells 14N/3E-24Q5 and 14N/3E-24Q4 (fig. 8B1), east of 

Bicycle Lake, indicated downward vertical flow. Water-level 

differences among wells 14N/3E-24Q3, 14N/3E-24Q2, and 

14N/3E-24Q1 indicated upward vertical flow to the depth 

perforated by well 14N/3E-24Q4, which had the lowest waterlevel altitudes of all wells at this site. 

In the monitoring wells 14N/3E-23B1–3 (fig. 8B3), there 

were large downward vertical hydraulic gradients between the 

shallow well 14N/3E-23B3 and the middle well 14N/3E-23B2 

and large upward vertical gradients between the deep well 

14N/3E-23B1 and the middle well 14N/3E-23B2. The large 

gaps in data were times when the water levels fell below the 

position of the recording pressure transducer. 

Continuous water-level responses in deep monitoring 

wells 14N/3E-13M2 and 14N/3E-23B1 that differed from 

shallower wells (14N/3E-13M3, 14N/3E-13M4, and 14N/3E23B2, and 14N/3E-23B3, respectively) indicated confined 

conditions in the lower aquifer at these sites. Supporting 

evidence for confined conditions included periodic larger 

drawdowns in 14N/3E-13M2 than in the shallower wells at 

this site (fig. 8B2). In addition, larger drawdowns and temporal 

responses in 14N/3E-23B1 compared to 14N/3E-23B3 

(fig. 8B3) indicated that the deep well (14N/3E-23B1) was in 

at least semi-confined conditions.
Geohydrologic Framework 27

Figure 8B4 shows continuous water levels for test 

wells 14N/3E-14P2, 14N/3E-23G1 and 14N/4E-18N2. Well 

14N/3E-14P2 is near production well 14N/3E-14P1, northwest 

of the multiple-well monitoring site 14N/3E-23B1–3 (fig. 2), 

and is perforated at similar depths as production well 14N/3E14P1. Water levels in well 14N/3E-14P2 showed seasonal 

fluctuations, pumping drawdown and rebound that were 

similar to well 14N/3E-23B2. Test well 14N/3E-23G1 is 

south of wells 14N/3E-23B1–3. Water levels in well 14N/3E23G1 represented the long, 560-ft perforated interval. The 

hydrograph showed no seasonal fluctuations, but did show 

a decline of about 5 ft over the 2-year period. A video log 

of 14N/3E-23G1 from February 2015 showed scaling in the 

well beginning at a depth of about 230 ft and heavy scaling 

below 530 ft. This information, coupled with the water-level 

data, suggested that water levels measured in this well were 

representative of the water table. Test well 14N/4E-18N2 is 

near production well 14N/4E-18N1, in the northeastern part of 

the basin. Water levels in well 14N/4E-18N2 showed similar 

seasonal fluctuations as in wells 14N/3E-14P2 and 14N/3E23B2. Drawdowns in well 14N/4E-18N2 could be less than 

in well 14N/3E-14P2 because the perforated interval in the 

monitoring well 14N/4E-18N2 is shorter and shallower than 

that in test well 14N/3E-14P2.

Land-Surface Deformation

Land-surface deformation, in the form of an earth fissure 

and sink-like depressions associated with land subsidence, 

was present on the Bicycle Lake (dry) playa; the playa is used 

as an aircraft runway for transporting troops and supplies to 

the base. Land-surface deformation attributed to groundwater 

pumping is found in many aquifer systems that, at least in part, 

are made up of unconsolidated, interbedded, fine- to coarsegrained deposits and have undergone extensive groundwater 

development (Poland, 1984). Several methods were used 

as part of this study to evaluate the cause of land-surface 

deformation in Bicycle Basin. These included Interferometric 

Synthetic Aperture Radar (InSAR), electromagnetic induction 

(EM), electrical resistivity tomography (ERT), and geodetic 

surveys. InSAR images were developed for Bicycle Basin and 

were used to map the areal extent and amount of vertical landsurface change in the basin. Electromagnetic induction and 

electrical resistivity data were collected to detect the presence 

and delineate the depth of earth fissures, macropolygons, and 

other related features. Geodetic surveys were done to monitor 

vertical and horizontal land-surface change across the basin, 

specifically on the playa, where InSAR does not work as 

well. This section briefly summarizes the InSAR methods 

used in the land-surface deformation study and presents maps 

showing the areal extent of the subsidence and time-series data 

calculated for input in the subsidence model. 

InSAR, a satellite-based remote sensing technique, is an 

effective way to measure vertical changes of land surface and 

can detect centimeter-level ground-surface displacement over 

a 62-by-62-mi (100-by-100-km) area with spatial resolution 

on the order of 295 ft (90 m) or less. This technique has been 

used to investigate deformation resulting from earthquakes 

(Massonnet and others, 1993), volcanoes (Massonnet and 

others, 1995), and land subsidence (Massonnet and others, 

1997; Fielding and others, 1998; Galloway and others, 1998; 

Amelung and others, 1999, Hoffmann and others, 2003; 

Sneed and Brandt, 2007). Synthetic Aperture Radar (SAR) 

data from the European Space Agency’s (ESA) European 

Remote Sensing satellites I and II (ERS-1 and ERS-2), and 

ENVISAT satellite were used to map and measure range 

(vertical) change. The satellites are side-looking, orbit the 

Earth at an altitude of approximately 497 mi (800 km), 

have 35-day repeat cycles, and have effectively the same 

accuracy. The use of InSAR involved the development and 

analysis of interferograms that show vertical changes in the 

ground surface between images. The interferograms had 

timelines ranging from 4.6 to 36.3 months, using 24 SAR 

scenes acquired during 1992–2000 by the ERS-1 and ERS-2 

satellites, and timelines ranging from 1.1 to 32.1 months, 

using 13 SAR scenes acquired during 2003–06 by the 

ENVISAT satellite (table 5).

Figure 9A shows the interferogram of land-surface 

deformation for November 30, 2003, through January 23, 

2005, during the period when the earth fissure was first 

detected. The direction of change—subsidence or uplift—is 

indicated by the color progression of the fringe toward the 

center of a deforming feature. The color-fringe progression of 

red-purple-blue-green-yellow-orange indicates subsidence; the 

opposite progression indicates uplift. 

During 2003–05, subsidence was identified in the area 

immediately north of Bicycle Lake (dry) playa. The nearest 

production well was 14N/3E-14P1. The area affected by 

subsidence was about 2.6 mi2

 and coincided with an area 

containing substantial clay deposits, as documented in 

lithology logs for wells 14N/3E-23B1–3, 14N/3E-14P1, 

14N/3E-14P2, and 14N/3E-23G1. Subsidence was not 

detected elsewhere in the basin, where lithology logs for wells 

14N/3E-24Q1–5, 14N/3E-13M2–4, 14N/3E-13M1, 14N/3E13K1, 14N/3E-14H1, 14N/3E-24H1, and 14N/4E-18N1 

indicated that clay deposits were less prevalent (fig. 3A, B; 

appendix 1).

Subsidence rates during 2003–06 were nearly double 

those during 1992–2000. Subsidence rates calculated from 

interferograms spanning 1992–2000 ranged from 0.02–

0.1 inches per month, or in./mo (0.62 to 2.6 millimeters per 

month [mm/mo]) and averaged 0.06 in./mo (1.5 mm/mo; 

table 5). Subsidence rates calculated from interferograms 

spanning 2003–06 ranged from 0–0.2 in./mo (0 to 

4.36 mm/mo) and averaged 0.1 in./mo (2.2 mm/mo). 

Furthermore, subsidence rates generally accelerated during 

1999–2000 and 2003–06 regardless of seasonal conditions, 

whereas subsidence rates during 1992–99 were more variable 

and correlated with seasonal conditions. The increase in 

subsidence rates after 1999 generally coincided with the start 

of pumping from well 14N/3E-14P1.
28 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Table 5. Acquisition dates of synthetic aperture radar data, interferogram timelines, and subsidence magnitudes and rates for 

72 interferograms analyzed for Bicycle Lake Basin, Fort Irwin National Training Center, California, 1992–2010.

[ERS-1 and ERS-2, European Space Agency’s (ESA) European Remote Sensing satellites I and II; ENVISAT, European Space Agency’s Environmental Satellite 

that replaced ERS-1 and ERS-2; in., inch; mm, millimeters; mm/dd/yyyy, month/day/year; —, not applicable]

Interferogram 

reference 

number

Acquisition dates Timeline 

of data 

collection

 (months)

Magnitude1 Rate1 Seasonal span of interferogram

Start

(mm/dd/yyyy)

End

(mm/dd/yyyy) (mm) (in.) (mm per month)

(in. per 

month)

Annual/

multi-annual

Winter/spring–

summer/fall

Summer/fall–

winter/spring

ERS-1 and ERS-2

1 08/07/1992 08/20/1995 36.3 25 0.98 0.69 0.03 x — —

2

2 11/05/1993 09/25/1995 22.6 30 1.18 1.33 0.05 x — —

2

3 01/08/1996 07/01/1996 5.7 5 0.20 0.87 0.03 — x —

2

4 10/14/1996 07/21/1997 9.2 15 0.59 1.63 0.06 x — —

5 09/25/1995 05/27/1996 8.0 10 0.39 1.24 0.05 — — x

2

6 06/16/1997 01/12/1998 6.9 10 0.39 1.45 0.06 — — x

7 08/05/1996 04/07/1997 8.0 5 0.20 0.62 0.02 — — x

8 08/05/1996 08/10/1998 24.1 30 1.18 1.24 0.05 x — —

9 03/03/1997 08/25/1997 5.7 15 0.59 2.61 0.10 — x —

10 03/03/1997 03/23/1998 12.6 25 0.98 1.98 0.08 x — —

11 04/07/1997 08/25/1997 4.6 10 0.39 2.18 0.09 — x —

12 08/25/1997 06/01/1998 9.2 10 0.39 1.09 0.04 — — x

2

13 03/23/1998 08/10/1998 4.6 10 0.39 2.18 0.09 — x —

14 03/23/1998 06/21/1999 14.9 25 0.98 1.68 0.07 — x —

15 07/06/1998 03/08/1999 8.0 10 0.39 1.24 0.05 — — x

2

16 08/10/1998 06/21/1999 10.3 10 0.39 0.97 0.04 x — —

2

17 07/26/1999 03/27/2000 8.0 20 0.79 2.49 0.10 — — x

2

18 03/27/2000 09/18/2000 5.7 15 0.59 2.61 0.10 — x —

ENVISAT

2

19 10/26/2003 06/27/2004 8.0 15 0.59 1.87 0.07 — — x

20 10/26/2003 11/14/2004 12.6 30 1.18 2.38 0.09 x — —

21 10/26/2003 12/19/2004 13.8 30 1.18 2.18 0.09 x — —

22 10/26/2003 02/27/2005 16.1 35 1.38 2.18 0.09 — — x

23 10/26/2003 04/03/2005 17.2 50 1.97 2.90 0.11 — — x

24 10/26/2003 06/12/2005 19.5 50 1.97 2.56 0.10 — — x

3

25 11/30/2003 01/23/2005 13.8 35 1.38 2.54 0.10 — — x

26 11/30/2003 09/25/2005 21.8 65 2.56 2.98 0.12 x — —

27 05/23/2004 01/23/2005 8.0 10 0.39 1.24 0.05 x — —

28 05/23/2004 04/03/2005 10.3 25 0.98 2.42 0.10 x — —

29 05/23/2004 07/17/2005 13.8 35 1.38 2.54 0.10 — x —

30 05/23/2004 09/25/2005 16.1 45 1.77 2.80 0.11 — x —

31 05/23/2004 04/23/2006 23.0 80 3.15 3.49 0.14 x — —

32 06/27/2004 11/14/2004 4.6 10 0.39 2.18 0.09 — — x

2

33 06/27/2004 02/27/2005 8.0 25 0.98 3.11 0.12 — — x

34 06/27/2004 03/19/2006 20.7 65 2.56 3.15 0.12 — — x

35 11/14/2004 12/19/2004 1.1 0 0.00 0.00 0.00 x — —

2

36 04/03/2005 06/12/2005 2.3 10 0.39 4.36 0.17 — — x

37 07/17/2005 09/25/2005 2.3 10 0.39 4.36 0.17 x — —
Geohydrologic Framework 29

Interferogram 

reference 

number

Acquisition dates Timeline 

of data 

collection

 (months)

Magnitude1 Rate1 Seasonal span of interferogram

Start

(mm/dd/yyyy)

End

(mm/dd/yyyy) (mm) (in.) (mm per month)

(in. per 

month)

Annual/

multi-annual

Winter/spring–

summer/fall

Summer/fall–

winter/spring

ENVISAT—Continued

2

38 07/17/2005 04/23/2006 9.2 30 1.18 3.27 0.13 — x —

39 01/23/2005 09/25/2005 8.0 25 0.98 3.11 0.12 — x —

2

40 02/27/2005 06/12/2005 3.4 10 0.39 2.90 0.11 — x —

41 02/27/2005 03/19/2006 12.6 45 1.77 3.56 0.14 x — —

42 02/27/2005 11/19/2006 20.7 60 2.36 2.90 0.11 — x —

43 02/27/2005 12/24/2006 21.8 65 2.56 2.98 0.12 x — —

44 04/03/2005 06/12/2005 2.3 5 0.20 2.18 0.09 x — —

45 04/03/2005 10/15/2006 18.4 50 1.97 2.72 0.11 — x —

46 06/12/2005 12/24/2006 18.4 60 2.36 3.27 0.13 — — x

2

47 07/17/2005 09/25/2005 2.3 10 0.39 4.36 0.17 x — —

48 07/17/2005 04/23/2006 9.2 35 1.38 3.81 0.15 — — x

2

49 09/25/2005 04/23/2006 6.9 30 1.18 4.36 0.17 — — x

2

50 03/19/2006 11/19/2006 8.0 25 0.98 3.11 0.12 — x —

51 10/15/2006 01/28/2007 3.4 15 0.59 4.36 0.17 — — x

52 10/15/2006 03/04/2007 4.6 15 0.59 3.27 0.13 — — x

2

53 10/15/2006 02/17/2008 16.1 35 1.38 2.18 0.09 — — x

54 12/24/2006 01/13/2008 12.6 30 1.18 2.38 0.09 x — —

55 12/24/2006 08/30/2009 32.1 75 2.95 2.33 0.09 — x —

56 01/28/2007 02/17/2008 12.6 25 0.98 1.98 0.08 x — —

57 03/04/2007 02/17/2008 11.5 25 0.98 2.18 0.09 x — —

58 08/26/2007 07/26/2009 23.0 50 1.97 2.18 0.09 x — —

59 01/13/2008 08/10/2008 6.9 15 0.59 2.18 0.09 — x —

60 01/13/2008 05/17/2009 16.1 25 0.98 1.56 0.06 x — —

61 02/17/2008 09/14/2008 6.9 20 0.79 2.90 0.11 — x —

2

62 02/17/2008 03/08/2009 12.6 25 0.98 1.98 0.08 x — —

63 02/17/2008 04/12/2009 13.8 30 1.18 2.18 0.09 x — —

64 08/10/2008 05/17/2009 9.2 15 0.59 1.63 0.06 — — x

65 09/14/2008 05/17/2009 8.0 10 0.39 1.24 0.05 — — x

66 03/08/2009 05/02/2010 13.8 15 0.59 1.09 0.04 x — —

2

67 03/08/2009 08/15/2010 17.2 20 0.79 1.16 0.05 — x —

68 04/12/2009 05/02/2010 12.6 15 0.59 1.19 0.05 x — —

69 05/17/2009 05/02/2010 11.5 15 0.59 1.31 0.05 x — —

70 05/17/2009 08/15/2010 14.9 25 0.98 1.68 0.07 — x —

71 08/30/2009 08/15/2010 11.5 15 0.59 1.31 0.05 x — —

72 05/02/2010 08/15/2010 3.4 10 0.39 2.90 0.11 — x —

1

Subsidence magnitudes in this table represent the line-of-sight ground-surface displacement (range change), which constitutes about 92 percent of true 

vertical change.

2

Used for the time series generation shown in figure 9B.

3

Shown in figure 9A.

Table 5. Acquisition dates of synthetic aperture radar data, interferogram timelines, and subsidence magnitudes and rates for 

72 interferograms analyzed for Bicycle Basin, Fort Irwin, California, 1992–2010.—Continued

[ERS-1 and ERS-2, European Space Agency’s (ESA) European Remote Sensing satellites I and II; ENVISAT, European Space Agency’s Environmental Satellite 

that replaced ERS-1 and ERS-2; in., inch; mm, millimeters; mm/dd/yyyy, month/day/year; —, not applicable]
30 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 9. Subsidence in Bicycle Basin, Fort Irwin National Training Center, California: A, interferogram showing subsidence contours 

for November 30, 2003, through January 23, 2005, faults, selected wells, and model calibration points, and B, interferogram-derived 

subsidence time-series data for six selected locations, 1993–2010.

sac11-0424_fig 09a

BARSTOW ROAD

Consolidated rock

Consolidated

rock

Consolidated rock

Consolidated

rock

30 (1.18)

20

10 (0.78) (0.39) 0

14P1 18N1

14H113M1 13K1

13M2-4

24Q1-5

23G1

24H1

14P2 18N2

23B1-3

PT2

PT3

PT1

PT2

23G1

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 0.5 1 KILOMETER

R. 3 E. R. 4 E.

T.

14

N.

EXPLANATION

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

South Coyote Canyon fault

Unnamed fault 1

North Bicycle Lake fault

Tiefort Mountain fault

Coyote Canyon fault zone

A

A’

B

B’

Unnamed fault 2

A

Bicycle Lake

(dry)

Township/range

Well used as model calibration-control point

 and identifier (see table 1)

Model calibration-control point and identifier

Well and identifier (see table 1) Subsidence contour-

 interval in millimeters

 (inches in parentheses)

10

Bicycle Lake (dry)

Section A–A’

Section B–B’

Fault

24H1

0 −32 mm

(−1.3 in.)

+32 mm

(+1.3 in.) 

Relative Subsidence Uplift
Geochemistry of Groundwater 31

The subsidence rates generally were higher during the 

summer and fall when water levels declined and were lower 

during the winter and spring when water levels recovered. 

Time-series data were generated for six selected locations 

used for model calibration to compute total subsidence for 

1993–2010 by ‘stacking’ interferograms, such that the end 

date for one interferogram was used as the beginning date for 

the next interferogram (fig. 9B). Where data gaps (2001–03 

and 2010–13) or overlaps existed, subsidence rates were 

used to compute magnitudes for the time interval of the gap 

or overlap, and the time series was adjusted accordingly. 

The time-series data were extrapolated from March 2009 to 

August 2010 using average subsidence rates computed from 

selected interferograms. 

Time-series data constructed for the six locations from 

1993 to 2010 indicated that subsidence ranged from about 

2.8 in. or 0.2 ft (70 millimeters, mm) at well 14N/3E-23G1 

to about 13.8 in. or 1.1 ft (350 mm) at well 14N/3E-23B1–3 

(fig. 9B). Average subsidence over this 17-yr period ranged 

from 0.16 inch per year (in./yr), or 0.01 foot per year, 

ft/yr (4 millimeters per year, mm/yr) to 0.8 in/yr or 

0.06 ft/yr (20.6 mm/yr). These subsidence data were used to 

calibrate the storage properties in the groundwater-flow model. 

Geochemistry of Groundwater

Water-quality samples were collected from 30 wells 

at 20 monitoring sites (appendix 3) in Bicycle Basin during 

1993–2011. In addition, one sequential replicate sample was 

collected from well 14N/3E-26K1 and evaluated to assess the 

precision of the water-quality data (Kjos and others, 2014). 

Six of the sites sampled were multiple-well monitoring sites; 

two sites contained two wells (14N/3E-35C2–3 and -22N1–2), 

three sites contained three wells (14N/3E-13M2–4, -23B1–3, 

and -26K1, 3, 4), and one site contained five wells (14N/3E24Q1–5). Wells 14N/3E-35C3 and 14N/3E-22N2 were dry 

and not sampled. The remaining 14 wells were monitoring 

wells, test wells, or production wells. 

Sample collection and processing followed the methods 

described in the USGS National Field Manual (Wilde and 

others, 1999, 2004). Groundwater samples were analyzed 

in the field for specific conductance, pH, temperature, and 

alkalinity. Water samples were analyzed in the laboratory 

for major ions, selected trace elements, nutrients, ratios 

of the stable oxygen (O) and hydrogen (H) isotopes, and 

concentrations of radioactive isotopes of tritium and carbon-14 

(

14C). Data collected as part of this study were supplemented 

with historical data for selected wells, from C.F. Hostrup 

and Associates (1955), Kunkel and Riley (1959), James M. 

Montgomery and Associates (1981), and Wilson F. So and 

Associates (1989). Additional nutrient and nitrogen isotope 

samples were collected and analyzed for wells in the firefighting training area. These results, reported in Densmore and 

Bohlke (2000), were included here.

Groundwater samples for major and minor ions, trace 

elements, alkalinity, and total dissolved solids analyses 

included both raw groundwater, and filtered groundwater 

(Wilde and others, 2004). Filtered samples were filtered using 

a 0.45-micrometer (μm) capsule filter. The filtered sample was 

preserved with nitric acid. The 14C samples were analyzed by 

accelerator mass spectrometry (Beukins, 1992). Major ions, 

selected trace elements, and nutrient samples were analyzed 

at the USGS National Water-Quality Laboratory (NWQL) 

or by laboratories contracted by the NWQL. Stable isotopes 

were analyzed by the USGS Stable Isotope Laboratory in 

Reston, Virginia, using methods described by Epstein and 

Mayeda (1953), Coplen and others (1991), and Coplen (1994). 

sac11-0424_fig 09b Subsidence, in feet

B

Year

61

0

366

305

244

183

122

Subsidence, in millimeters

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012

0.0

0.2

0.4

0.6

0.8

1.0

1.2

EXPLANATION

Wells

Control points

Subsidence

PT1

PT2

PT3

14N/3E-14P1S

14N/3E-23B1S, -23B2S, 

 -23B3S

14N/3E-23G1S

Figure 9. —Continued
32 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Carbon-14 was analyzed by Woods Hole Oceanographic 

Institution, National Ocean Sciences Accelerator Mass 

Spectrometry Facility (NOSAMS) in Massachusetts, using 

methods described by Vogel and others (1987), Donahue and 

others (1990), Gagnon and Jones (1993), and Schneider and 

others (1994). Tritium was analyzed by the USGS Stable 

Isotope and Tritium Laboratory in Menlo Park, California, 

using methods described by Thatcher and others (1977). These 

data are in the USGS NWIS database and can be accessed at 

https://waterdata.usgs.gov/ca/nwis.

General Water-Quality Characteristics and 

Areal Variation

The chemistry of the recharge water and various 

geochemical reactions, including dissolution, precipitation of 

minerals in the subsurface, and evapoconcentration, controlled 

the major-ion chemistry of the groundwater in the Bicycle 

Basin. To visually characterize differences among majorion chemistry (water types) in the Bicycle Basin, trilinear 

diagrams were plotted using a method described by Piper 

(1945; figs. 10A–C). To further describe general quality and 

areal differences, water-quality diagrams were produced using 

a method suggested by Stiff (1951; fig. 11).

Trilinear diagrams are a graphical representation of the 

relative contribution of major cations and anions to the total 

ionic content of the water. A percentage scale shows the cation 

concentrations on the upper right and lower left sides of the 

diamond and the anion concentrations on the upper left and 

lower right sides. The position of a sample on the diagram 

gives an indication of the chemical character of the water and 

allows a comparison to be made among different samples. 

Trilinear diagrams were prepared from samples collected 

during 1965–2011 with complete analyses from each well for 

the northern, central, and southern part of the basin (figs. 10A–

C). The north area (fig. 10A) includes five wells that are north 

of the South Coyote Canyon fault. The central area (fig. 10B) 

includes 14 wells that are between South Coyote Canyon fault 

and unnamed fault 1. The south area (fig. 10C) includes eight 

wells that are south of unnamed fault 1.

Groundwater in Bicycle Basin varied from sodiumbicarbonate-sulfate (NaHCO3

-SO4)-type water to sodiumbicarbonate-chloride (NaHCO3

-Cl)-type water, depending on 

the sulfate and chloride concentrations, and sodium-chloride 

(NaCl)-type water. Groundwater from wells in the north area 

(fig. 10A) was NaHCO3-SO4-type water. Groundwater from 

wells in the central area (fig. 10B) ranged from NaHCO3-SO4

along the western side of the basin to NaHCO3-Cl, as chloride 

(Cl) becomes more dominant than sulfate (SO4), in wells near 

the playa (perforated in Quaternary-Tertiary older alluvium 

(QToa) and along the eastern side of the basin (perforated in 

Tertiary older gravels (Tog). Groundwater from wells in the 

south area (fig. 10C) was generally NaHCO3-SO4-type water, 

with the exception of wells 14N/3E-27E1 and 14N/3E-28A1, 

which are perforated in Tertiary (Tog) deposits. Firefighting 

training activities in the vicinity of wells 14N/3E-27E1–3, 

-28A1, and -28H1–2 (fig. 2) impacted groundwater in wells 

14N/3E-27E1 and 14N/3E-28A1 by evapoconcentration and 

leaching of salts from the soils (Densmore and Bohlke, 2000), 

causing increased nitrate concentrations.

Water-quality diagrams show the general quality 

differences in the chemical character of the water by location 

(fig. 11). Similarly shaped diagrams indicate the presence of 

groundwater with similar major-ion characteristics. The width 

of the diagrams differs, according to the concentrations of 

dissolved solids. 

Relatively poor groundwater quality with higher total 

dissolved solids appeared to be associated primarily with 

water withdrawn from wells perforated in the QuaternaryTertiary older alluvium, QToa (likely evaporite deposits), 

and Tertiary older gravels, Tog. Groundwater quality was 

relatively poor, with total dissolved solids (TDS) ranging from 

786 to 1,130 milligrams per liter (mg/L) and NaCl-type waters 

in six wells: 14N/3E-23B2, 14N/3E-24Q1, 14N/3E-24Q2, 

14N/3E-27E1, 14N/3E-28A1, and 14N/4E-18N1 (fig. 11). 

Groundwater in these wells differed from other wells in that 

it is enriched in chloride and depleted in bicarbonate (HCO3

). 

Five of these six wells have the bottom of perforations in the 

Tertiary older gravels (Tog). Four of these wells, 14N/4E18N1, 14N/3E-23B2, 14N/3E-24Q1, and 14N/3E-24Q2, are 

in the central area (fig. 10B), and two wells, 14N/3E-27E1 

and 14N/3E-28A1, are in the southern area (fig. 10C). Well 

14N/4E-18N1 is perforated from 300 to 780 ft in QuaternaryTertiary older alluvium and Tertiary gravels (QToa, Tyg, 

and Tog) northeast of the playa; however, the water quality 

was more reflective of the Tertiary older gravels (Tog). Well 

14N/3E-23B2 is perforated from 440 to 460 ft in QuaternaryTertiary older alluvium (QToa) in the area of greatest 

subsidence, west of the playa; however, the water quality 

likely was more representative of evaporite deposits, such as 

the Quaternary-Tertiary older lacustrine deposits (QTol). Wells 

14N/3E-24Q1 and 14N/3E-24Q2 are perforated from 878 to 

898 ft and from 725 to 745 ft, respectively, in Tertiary older 

gravels (Tog) on the east side of Bicycle Lake (dry) playa. 

The relatively high-salinity (TDS of 1,130 mg/L) water 

present in well 14N/3E-23B2 likely originated from buried 

lacustrine or playa (evaporite) deposits. Groundwater quality 

near playas generally reflected the lateral flow of groundwater 

and remobilization of buried salts from evaporate deposits. 

Geophysical surveys of Bicycle Lake (dry) playa showed 

higher conductivity in the shallow subsurface in the northern 

part of the Bicycle Lake (dry) playa, and core-sample x-ray 

diffraction analysis of shallow surficial deposits (Qp) showed 

that halite (NaCl) was present (Craig Rasmussen, University 

of Arizona, written commun., 2010). These data indicated 

that NaCl also would be expected in buried playa deposits. 
sac11-0424_fig 10abc

Sodium (Na) + Potassium (K) 

 0 

 20 

 40 

 60 

 80 

Sulfate (SO4) + Chloride (Cl)

 0 

 20 

 40 

 60 

 80 

PERCENT

PERCENT Sodium (Na) + Potassium (K) Carbonate (CO3) + Bicarbonate (HCO3)

 0 

 20 

 40 

 60 

 80 

 100 

Sulfate (SO4) + Chloride (Cl)

 0 

 20 

 40 

 60 

 80 

 100 

Calcium (Ca) + Magnesium (Mg)

 100 

 80 

 60 

 40 

 20 

 0 

 100 

 80 

 60 

 40 

 20 

 0 

PERCENT

PERCENT

PERCENT

PERCENT Sodium (Na) + Potassium (K) Carbonate (CO3) + Bicarbonate (HCO3)

 0 

 20 

 40 

 60 

 80 

 100 

Sulfate (SO4) + Chloride (Cl)

 0 

 20 

 40 

 60 

 80 

 100 

Calcium (Ca) + Magnesium (Mg)

 100 

 80 

 60 

 40 

 20 

 0 

 100 

 80 

 60 

 40 

 20 

 0 

PERCENT

PERCENT

PERCENT

PERCENT

A B C

EXPLANATION EXPLANATION EXP

North Center 

14N/3E-26K3S14N/3E-26K4S

14N/3E-26K1S

QToa

Tyg

14N/3E-13M1S14N/3E-14H1S

14N/3E-13M3S

QToa

QToa2/1

14N/3E-13M4S

QToa2

14N/3E-13M2S

Tyg

14N/3E-13K1S14N/3E-14P1S14N/3E-14P2S

14N/3E-23B3S14N/3E-24Q5S

QToa

QToa2

14N/3E-23B2S14N/3E-24Q4S

QToa1

14N/3E-23B1S14N/3E-24Q3S

Tyg

14N/3E-24Q1S14N/3E-24Q2S

Tog

14N/4E-18N1S

QToa, Tyg, Tog

14N/3E-24H1S

QToa, QTol

14N/3E-23G1S

QToa, QTol, Tyg

[QToa, Quaternary-Tertiary older alluvium; QTol, Quaternary-Tertiary older lacustrine; Tog, Tertiary older gravels; Tyg, Tertiary younger gravels; Bc, Basement comple

Figure 10. Water-quality data for selected wells in the following areas in Bicycle Basin, Fort Irwin National Training Center, California: A, north, B, ce

of wells shown on figure 2).
34 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 11. Water-quality diagrams and dissolved-solids concentrations of groundwater from selected wells in Bicycle Basin, Fort Irwin 

National Training Center, California.

sac11-0424_fig 11

South Coyote Canyon fault

Unnamed fault 1

North Bicycle Lake fault

Tiefort Mountain fault

Coyote Canyon fault zone

A

A’

B

B

Unnamed fault 2

Bicycle

Lake

(dry)

14P2

(1988)

458

23B3

(2010)

601

23B2

(2010)

1,130 23B1

(2010)

581 23G1

(2010)

789 24Q5

(2000)

590

24Q1

(2000)

822

26K4

(2011)

545

26K3

(2011)

645

26K1

(2011)

551

24Q2

(2000)

1,030

24Q3

(2000)

499

24Q4

(2000)

557

35C1

(2000)

654

13M3

(2000)

574

13M2

(2000)

655

13M4

(2000)

572

13K1

(1993)

480

13M1

(1994)

592

14H1

(1993)

584

22N1

(1997)

541

14P1

(2000)

579

22P1

(1980)

565

24H1

(1994)

498

18N1

(2010)

786

28A1

(1995)

1,080

27E1

(1995)

879

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 0.5 1 KILOMETER

EXPLANATION

R. 3 E. R. 4. E.

T.

14

N.

A

A’

B’

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

Production

Multiple-well

 monitoring site

Destroyed

Test well

Obstructed

22P1

28A3

14H1

14P1

Stiff diagram with stacked identifier

Cl

HCO3

+CO3

SO Mg 4

Ca

Na+

K

10 5 0 5 10

Cations Anions

Milliequivalents per liter

Wells type and identifier (see table 1)

Bicycle groundwater basin

Bicycle Basin

Model inferred faults

Faults

Bicycle Lake (dry)

Section A–A’

Section B–B’

Township/range

North

Central

South

26K1

(2011)

551

 Well identifier 

 (see table 1)

 Sample year

 Total dissolved solids, 

 in milligrams per liter

24H1
Geochemistry of Groundwater 35

Groundwater contacting evaporite deposits would be expected 

to have higher salinity and could move laterally from the 

evaporite deposits toward the production well 14N/3E-14P1, 

northwest of well 14N/3E-23B2. Well 14N/3E-23B2 is the 

middle well of a multiple-well monitoring site. Saline water 

was not present in the shallower (14N/3E-23B3) or deeper 

(14N/3E-23B1) wells, which are perforated in QuaternaryTertiary older alluvium and Tertiary younger gravels (QToa 

and Tyg), respectively.

The relatively high TDS water in wells 14N/3E-24Q1, 

14N/3E-24Q2, and 4N/4E-18N1 was enriched in calcium and 

was primarily from wells perforated in Tertiary older gravels 

(Tog) at depth (fig. 10B). Wells 14N/3E-24Q1 and 14N/3E24Q2 are the deepest wells in a multiple-well monitoring 

site. Relatively high TDS water was not in the shallow wells 

perforated in Quaternary-Tertiary older alluvium (QToa) at 

this site. The relatively high-salinity water could represent the 

typical water-quality characteristic of old, deep groundwater in 

the Tertiary older gravels (Tog), which might move laterally or 

vertically toward well 14N/4E-18N1, which is north of wells 

14N/3E-24Q1 and 14N/3E-24Q2. 

The relatively high TDS water in wells 14N/3E-27E1 and 

14N/3E-28A1 in the southwestern part of the basin might be 

influenced partly by firefighting activities, described later, or 

could reflect old groundwater from the Tertiary older gravels 

(Tog), similar to that of other wells perforated in Tertiary 

older gravels (Tog). The perforated intervals of wells 14N/3E27E1 and 14N/3E-28A1 are unknown; however, these wells 

could be perforated in Tertiary older gravels (Tog), similar 

to the deposits exposed nearby at land surface. The source 

of the increased salinity in wells 14N/3E-27E1 and 14N/3E28A1 might not be the evaporite deposits encountered in the 

wells in the central area, however. Nitrogen isotope analyses 

of soil-leachate and well samples collected to identify 

source of nitrate (Densmore and Bohlke, 2000) indicated the 

groundwater near these wells had been affected by firefighting 

training. Water sprayed on burning material resulted in 

leaching of nitrates from the soils into the groundwater in 

this area. It is likely that sodium and chloride also would be 

leached from the soils in addition to their concentration by 

evaporation of the sprayed water.

As described in the previous section, groundwater quality 

varied with depth and from the western side to eastern side 

of the basin, perhaps primarily reflecting spatial variations in 

well depth (fig. 11). In general, groundwater in wells 14N/3E14H1 in the northern area, 14N/3E-13K1, 14N/3E-14P1, 

14N/3E-14P2, 14N/3E-23B1, 14N/3E-23B3, and 14N/3E24Q5, in the central area of Bicycle Basin, perforated at least 

partly in the Quaternary-Tertiary alluvium (or Tertiary younger 

gravels, in the case of 14N/3E-23B1), was NaHCO3

-SO4-type 

water. Groundwater in wells 14N/3E-23G1, 14N/3E-24H1, 

14N/3E-24Q3, and 14N/3E-24Q4, near the playa and on the 

eastern side of the basin, was NaHCO3-Cl-type water, with 

chloride becoming more prominent than sulfate. Groundwater 

in well 14N/3E-24Q5 began to shift to NaHCO3-Cl-type water 

in 2011 as the chloride content increased (appendix 3). 

Total dissolved-solids (TDS), chloride (Cl), and nitrite 

plus nitrate as nitrogen (NO2 and NO3 as N) concentrations 

were used to further describe the areal variation in 

groundwater from Bicycle Basin. For simplicity, only TDS 

concentrations for the most recent sample (from 1988 to 2011) 

from each well are shown in figure 11. Water-quality data 

collected during 1993–2011 for this study are presented in 

appendix 3. Because nitrite concentrations in these samples 

were generally below the detection limit, nitrite plus nitrate 

(appendix 3) were used as an approximation of nitrate as 

nitrogen concentrations of groundwater in Bicycle Basin. The 

TDS concentrations in groundwater in Bicycle Basin ranged 

from about 458 mg/L TDS in well 14N/3E-14P2 (Wilson 

F. So and Associates, 1989) to about 2,500 mg/L TDS in 

well 14N/3E-23G1 (James M. Montgomery and Associates, 

1981). The chloride concentrations ranged from 59 mg/L in 

well 14N/3E-14P1 (Wilson F. So and Associates, 1989) to 

1,000 mg/L in well 14N/3E-23G1 (James M. Montgomery 

and Associates, 1981). The nitrate concentrations ranged 

from 0.72 mg/L NO3 as N in well 14N/3E-23G1 (James M. 

Montgomery and Associates, 1981) to 31 mg/L NO3 as N in 

well 14N/3E-28A1 (appendix 3). 

The highest TDS and chloride concentrations in 

groundwater were in a sample collected in 1980 from well 

14N/3E-23G1 immediately after the well was drilled and 

could represent the quality of water influenced by contact 

with evaporate deposits beneath the playa. These high 

concentrations were not observed in later samples from 

this well. During 2010, TDS and chloride concentrations in 

14N/3E-23G1 were 789 mg/L and 145 mg/L, respectively. 

The change in quality could indicate that the well had not 

been thoroughly developed prior to sampling in 1980 or that 

portions of the screens in this well have become partially 

clogged as a result of scaling in the well over time, changing 

the depth distribution of inflow and water quality in the well. 

The 1980 concentrations in water from this well might be 

representative of relatively saline water that was present in 

the Quaternary-Tertiary older alluvium (QToa), lacustrine 

(QTol), and Tertiary deposits, opposite the perforations in 

this well (table 1). Relatively high concentrations of TDS and 

chloride also were detected in groundwater in well 14N/3E23B2 during 2010 and, during 2000, in well 14N/3E-24Q2, 

east of the playa. The high concentrations in groundwater 

from these wells are of concern because poor-quality water 

from these areas could migrate toward the production wells 

as water levels decline, causing water quality to degrade. 

Except for these wells, groundwater from most wells generally 

contained less than 700 mg/L TDS and less than 100 mg/L 

chloride. A secondary maximum contaminant level of 500 

mg/L for TDS and 250 mg/L for chloride were established by 

the U.S. Environmental Protection Agency (2002) for aesthetic 

purposes of taste. 
36 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The highest nitrate concentrations were in groundwater 

from wells 14N/3E-27E1, -27E2, -27E3, -28A1, and -28H2, 

in the firefighting training area in the southwestern part of 

the basin (Densmore and Bohlke, 2000). Although perforated 

intervals are not known for these wells, wells 14N/3E-28A1 

and -28H2 are reportedly shallow, 151 and 164 ft, respectively 

(table 1). As described previously, water sprayed on burning 

material resulted in leaching of nitrates from the soils into the 

groundwater in this area. These groundwater samples were 

not representative of native groundwater in the basin and are 

not included further in this discussion. Elevated nitrate as 

nitrogen concentrations (9.51–11.5 mg/L in the late 1970s) 

were measured in groundwater from one other well, 14N/3E35C1. Nitrate as nitrogen concentrations decreased to about 

7 mg/L in 2000 (appendix 3). Elevated nitrate as nitrogen 

concentrations in well 14N/3E-35C1 could have resulted from 

infiltration of wastewater from the septic system at the airport. 

These groundwater samples also were not representative 

of native groundwater and are not included further in 

this discussion. 

Excluding wells 14N/3E-27E1–3, -28A1, -28H2, and 

-35C1, nitrate concentrations ranged from less than 1 mg/L 

NO3 as N in well 14N/3E-23B2 (2010) to 8.7 mg/L NO3

as N in well 14N/3E-23G1 (1993). The nitrate as nitrogen 

concentrations of native groundwater in Bicycle Basin, 

as sampled from wells in areas with no evident sources 

of contamination, were generally less than 5 mg/L. This 

concentration was slightly higher than background levels 

of nitrate (2–3 mg/L) measured in desert environments 

(Umari and others, 1993) and in Irwin and Langford Basins 

(Densmore and Londquist, 1997; Voronin and others, 2013). 

The nitrate as nitrogen concentrations (8.4–8.7 mg/L) were 

high in groundwater from well 14N/3E-23G1. Well 14N/3E23G1, west of the playa, has a long screened interval (178–

737 ft) that perforates Quaternary-Tertiary older alluvium 

(QToa) and Quaternary-Tertiary older lacustrine deposits 

(QTol). The elevated nitrate as nitrogen concentrations may 

be derived from the fine-grained Quaternary-Tertiary deposits 

(QTol). Evidence indicates that nitrate concentrations in 

groundwater from nearby multiple-well monitoring well 

site 14N/3E-23B1–3 were higher in groundwater from 

the shallow well (14N/3E-23B3 perforated at the base of 

QToa and near the top of QTol) than in groundwater from 

the two deeper wells (14N/3E-23B1–2) perforated below 

Quaternary-Tertiary older lacustrine deposits (QTol). A 

primary maximum contaminant level of 10 mg/L for nitrate as 

nitrogen was established by the U.S. Environmental Protection 

Agency (2002). 

Other constituents of concern in groundwater in desert 

areas are arsenic (As) and fluoride (F). High concentrations 

of arsenic and fluoride were present in many desert basins at 

Ft. Irwin (Densmore and Londquist, 1997; Voronin and others, 

2013). These constituents tended to concentrate in fine-grained 

deposits and generally are associated with basin-fill deposits 

of alluvial-lacustrine origin, particularly in semi-arid areas, 

and volcanic deposits (Welch, and others, 1988; García and 

Borgnino, 2015). Concentrations of arsenic in groundwater 

in Bicycle Basin ranged from 2 micrograms per liter (μg/L) 

at well 14N/3E-24Q2, east of the playa, to 103 μg/L at well 

14N/3E-23B1, northwest of the playa in the area of greatest 

subsidence (appendix 3). Concentrations of fluoride ranged 

from 0.5 mg/L in water from well 14N/4E-18N1, northeast 

of the playa, to 8.1 mg/L in water from well 14N/3E-23G1, 

immediately west of the playa (James M. Montgomery and 

Associates, 1981). The fluoride concentration in water from 

well 14N/3E-23G1 was 5.74 mg/L in 2010; in water from 

nearby well 14N/3E-23B2, fluoride was 7.81 mg/L in 2011 

(appendix 3). In general, concentrations in groundwater 

from most wells in Bicycle Basin were greater than 10 μg/L 

for arsenic, except in wells 14N/3E-22N1, 14N/3E-24H1, 

14N/3E-24Q1–3, and 14N/4E-18N1, and less than 4 mg/L 

for fluoride, except in wells 14N/3E-23B2, 14N/3E-23G1, 

and 14N/3E-35C1–2. Arsenic and fluoride concentrations 

remained fairly constant over time in groundwater in the 

basin, except in shallow wells 14N/3E-24Q3, 4, 5, where 

arsenic concentrations decreased, and in well 14N/3E13M4, where fluoride concentration decreased. The primary 

maximum contaminant level of arsenic in drinking water, 

initially established at 50 μg/L by the U.S. Environmental 

Protection Agency (2002), was lowered to 10 μg/L in 2006 

(U.S. Environmental Protection Agency, accessed Aug 4, 

2010, at http://www.epa.gov/safewater/contaminants/index.

html#7). For fluoride, the primary maximum contaminant 

level of 4 mg/L F has been established as a drinking water 

guideline for public water systems (U.S. Environmental 

Protection Agency, 2002).

Source and Age of Groundwater

The stable isotopic ratios of oxygen (oxygen-18/

oxygen-16, δ18O) and hydrogen (hydrogen-2,2H, or deuterium/

hydrogen-1, δD) were analyzed in groundwater samples to 

help determine the source and movement of water through 

the study area. The activity of the radioactive isotopes of 

hydrogen (hydrogen-3, 3H, or tritium) and carbon (14C) was 

analyzed in groundwater samples to determine the relative 

age, or time since recharge, of groundwater in Bicycle Basin. 

A total of 56 water samples collected from 25 wells were 

analyzed for δ18O and δD. Samples from selected wells also 

were analyzed for 3H and 14C (appendix 3).
Geochemistry of Groundwater 37

Stable Isotopes of Oxygen and Hydrogen

Oxygen-18 (18O) and deuterium (D) are natural stable 

isotopes of oxygen and hydrogen, respectively. Their isotopic 

ratios are expressed relative to the standard, known as Vienna 

Standard Mean Ocean Water (VSMOW), in delta notation (δ) 

as per mil (parts per thousand) differences (Gonfiantini, 1978). 

More negative values of δ18O and δD represent enrichment 

in the lighter isotopes, 16O and 1H (or depletion in the heavier 

isotopes, 18O and D); less negative values represent enrichment 

in the heavier isotopes of oxygen (18O) and hydrogen (D). 

The ratios of oxygen isotopes (18O:16O) and hydrogen isotopes 

(D:1H) in groundwater are indicators of the hydrologic history 

of the groundwater.

The linear relation between δ18O and δD in natural 

precipitation throughout the world (Craig, 1961) is referred 

to as the global meteoric water line (fig. 12). The isotopes 

of oxygen and hydrogen in ocean water are fractionated as 

the lighter isotopes 16O and 1

H are preferentially transferred 

during the phase change to vapor during evaporation at the 

ocean surface. During rainfall, water in the atmosphere is 

fractionated further, as 18O and D are preferentially condensed 

in precipitation, leaving the remaining water vapor relatively 

depleted in the heavier isotopes. Latitude, altitude, and air 

temperature affect the isotopic composition of atmospheric 

water. Precipitation from a given storm becomes isotopically 

lighter (more negative) as the storm moves inland and into 

higher altitudes with cooler temperatures (Fournier and 

Thompson, 1980). Water that has undergone evaporation is 

enriched in heavier isotopes relative to its original composition 

and generally has values below and to the right of the meteoric 

water line, with a slope between 3 and 6 (International 

Atomic Energy Agency, 1981). There is no further change 

in isotopic composition at the relatively low temperatures of 

most groundwater systems after recharged water has migrated 

below the depth of evaporation. Any subsequent differences 

in the isotopic composition of groundwater along a flow line, 

therefore, generally reflect only mixing within the aquifer 

system or concentration by evaporation in a discharge area. 

The δ18O and δD composition of groundwater, relative to 

the meteoric water line and the isotopic composition of 

water from other sources, can be an indicator of the source 

of groundwater.

Groundwater that is isotopically lighter than modernday precipitation could indicate groundwater was recharged 

under conditions that were cooler than present-day conditions 

(Smith and others, 2002) or that modern-day precipitation is 

more variable than the available data indicate. The isotopic 

compositions of groundwater from the wells and one spring 

in the Irwin, Langford, and Bicycle Basins plotted to the 

right or below the meteoric water line and available nearby 

precipitation data (fig. 12A; Friedman and others, 1992; 

Izbicki, 2004). The isotopic composition of groundwater 

from wells in Bicycle Basin ranged from about –10.4 to 

–13.4 per mil δ18O and –86 to –102 per mil δD (appendix 3). 

The groundwater isotopic data to the right of the global 

meteoric water line indicated possible evaporation prior 

to recharge, partial evaporation during precipitation, or a 

“local” meteoric water line that differs slightly from the 

global meteoric water line. Volume-weighted samples of local 

precipitation at Daggett FAA Airport (Friedman and others, 

1992) and averaged desert winter precipitation (Izbicki, 2004), 

representing modern-day precipitation in the western Mojave 

Desert, plotted near the global meteoric water line (fig. 12A). 

A volume-weighted sample of local precipitation at Goldstone 

Echo 2 (Friedman and others, 1992) plotted to the right of the 

meteoric water line and slightly above and to the right of the 

groundwater samples (fig. 12B). This sample, representing 

precipitation collected during summer 1985 through winter 

1987, was notably different than the weighted average for 

winter precipitation in the Mojave Desert and could represent 

“local” meteoric water. 

The groundwater from wells in the Bicycle Basin was 

isotopically lighter than groundwater from wells in Irwin and 

Langford Basins, plotting to the left of most of the samples 

from Irwin and Langford Basins. This indicated that the 

precipitation runoff recharging Bicycle Basin originated at 

a higher altitude than in the other basins. As it does today, 

groundwater in Bicycle Basin likely recharged from storm 

runoff and underflow in the higher elevations of the Granite 

Mountains, to the north and northwest, and the Goldstone 

upland area, to the west (fig. 1). As in Irwin and Langford 

Basins, the isotopic composition of groundwater in Bicycle 

Basin indicated that groundwater from most wells in 

Bicycle Basin was recharged during a cooler, wetter period 

than is characteristic of present-day climatic conditions. 

Groundwater in Bicycle Basin from wells perforated in the 

deeper Quaternary-Tertiary deposits and Tertiary deposits 

(table 1) generally was isotopically lighter (more negative) 

than groundwater from wells perforated in the shallower 

Quaternary-Tertiary deposits (figs. 3, 12B). Wells 14N/3E13M1, 14N/3E-13M2, 14N/3E-14H1, 14N/3E-23B1–2, 

14N/3E-24H1, 14N/3E-24Q1–3, and 14N/4E-18N1 are 

fully or partially perforated in deeper Quaternary-Tertiary 

and Tertiary deposits and had groundwater ranging from 

about –12.1 to –13.2 per mil δ18O and –95 to –105 per mil 

δD (appendix 3). Groundwater from wells perforated in 

shallower Quaternary-Tertiary deposits ranged from about 

–11.1 to –12.4 per mil δ18O and –90 to –95 per mil δD, slightly 

enriched in δ18O and δD; this difference indicated groundwater 

from these wells was recharged from a different source or 

storm trajectory. In addition, these data indicated that the 

source of recharge to Bicycle Basin had become more like 

the source of recharge in Irwin and Langford Basins during 

the Quaternary. Deeper groundwater was recharged near the 

end of the last North American glaciations, as described in 

the following “Tritium and Carbon-14” section, when storms 

were colder and conditions wetter, resulting in lighter (more 

negative) isotope ratios than younger postglacial recharge.
38 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 12. Stable isotopes of groundwater samples from Fort Irwin National Training Center, California, along with reported weightedaverage precipitation measurements for A, Irwin, Langford, and Bicycle Basins and B, for Bicycle Basin by geology.

sac11-0424_fig 12ab

Tertiary

samples

(Tyg, Tog)

Basement

Complex

(Bc)

Evaporated

Tertiary

samples

(Tog)

Meteoric Water Line (Craig, 1961)

Weighted-average precipitation, winter

 (Izbicki, 2004)

Weighted-average precipitation, Goldstone

 (Friedman and others, 1992)

EXPLANATION

Bc

QToa

Tog

Tyg

QToa, QTol

14N/3E-22N1S

14N/3E-35C1S

14N/3E-35C2S

14N/3E-27E1S, 

 -28A1S

14N/3E-24Q4S, 

 -24Q5S

14N/3E-13M4S

14N/3E-13M3S

14N/3E-23B3S

14N/3E-14P1S

14N/3E-14H1S

14N/3E-23B2S

14N/3E-26K3S

14N/3E-24K4S

14N/3E-13M2S

14N/3E-23B1S

14N/3E-26K1S

QToa, Tyg, Tog

QToa, Tyg

Tog, Tyg

14N/3E-24Q1S, 

 -24Q2S, -24Q3S

14N/3E-24H1S

Qoa, QToa

14N/3E-13M1S

14N/4E-18N1S

14N/3E-23G1S

Samples grouped by geologic unit

EXPLANATION

Meteoric Water Line

 (Craig, 1961)

Irwin wells

Langford wells

Garlic Spring

Volume-weighted-average 

 precipitation at Daggett

 (Friedman and others, 1992)

Weighted-average desert 

 winter precipitation

 (Izbicki, 2004)

Bicycle wells 

[Qoa, Quaternary older alluvium; QToa, QuaternaryTertiary older alluvium; QTol, Quaternary-Tertiary 

older lacustrine; Tyg, Tertiary younger gravels; Tog, 

Tertiary older gravels; Bc, Basement complex]

−105 

−100 

−95 

−90 

−85 

−80 

−75 

−70 

−65 

delta Deuterium, per mil 

B

−14 −13 −12 −11 −10 −9 −8 

delta Oxygen-18, per mil 

−100 

−95 

−90 

−85 

−80 

−75 

−70 

−65 

delta Deuterium, per mil 

A

−105 

−14 −13 −12 −11 −10 −9 −8 −7 

delta Oxygen-18, per mil 
Geochemistry of Groundwater 39

Tritium and Carbon-14

Tritium (3H) is a natural radioactive isotope of hydrogen 

that has a half-life of 12.4 years. The concentration of tritium 

is reported in tritium units (TU; Bartolino and Cole, 2002). 

Approximately 1,760 pounds (800 kilograms) of tritium was 

released into the atmosphere from the atmospheric testing of 

nuclear weapons between 1952 and 1962 (Michel, 1976). As a 

result, tritium concentrations in precipitation and groundwater 

recharge increased during that time. Tritium concentrations 

are not affected by chemical reactions other than radioactive 

decay, because tritium is part of the water molecule. 

Therefore, tritium is a tracer of the movement and relative age 

of water on timescales ranging from recent to about 50 years 

before present (post 1952). In this report, groundwater that 

had tritium (3H) concentrations less than a limit of 0.2 TU was 

interpreted as water recharged prior to 1952, and groundwater 

that had measurable 3

H concentrations was interpreted as 

water recharged after 1952, or recent recharge. 

Carbon-14 is a natural radioactive isotope of carbon that 

has a half-life of about 5,730 years (Mook, 1980). Carbon-14 

data are expressed as percent-modern carbon (pmC) by 

comparing 14C activities to the specific activity of National 

Bureau of Standards oxalic acid: 13.56 disintegrations per 

minute per gram of carbon in the year 1950 equals 100 pmC 

(Kalin, 2000). Carbon-14 was produced, as was tritium, by 

the atmospheric testing of nuclear weapons (Mook, 1980). 

As a result, 14C activities can exceed 100 pmC in areas 

where groundwater contains tritium. Carbon-14 activities 

are used to determine the age of a groundwater sample on 

timescales ranging from recent to more than 20,000 years 

before present. Carbon-14 is not part of the water molecule, 

and, therefore, 14C activities can be affected by chemical 

reactions that remove or add carbon to solution. In addition, 

14C activities are affected by mixing younger water that has 

high 14C activity with older water that has low 14C activity. 

Carbon-14 ages presented in this report did not account for 

changes in 14C activity resulting from chemical reactions or 

mixing and, therefore, were considered uncorrected ages. In 

general, uncorrected 14C ages are older than the actual age of 

the associated water. Izbicki and others (1995) estimated that 

uncorrected 14C ages were as much as 30 percent older than 

the actual ages of groundwater in the regional aquifer in the 

Mojave River groundwater basin near Victorville, California 

(not shown), about 60 mi southwest of the study area. In this 

report, groundwater that had 14C activities less than 90 pmC 

was interpreted as being recharged before 1952; groundwater 

having 14C activities greater than 90 pmC was interpreted as 

being recharged after 1952 (Izbicki and Michel, 2004).

The lack of 3H in samples from Bicycle Basin indicated 

that water throughout most of Bicycle Basin was recharged 

prior to 1952. Measurable concentrations of 3H were present 

in only one groundwater sample from 20 wells in Bicycle 

Basin (appendix 3; fig. 13). Well 14N/3E-23B2 had a low, but 

detectable 3H of 0.22 TU, indicating that some groundwater 

recharged since the early 1950s could be mixed in with 

primarily older groundwater.

The uncorrected 14C data indicated the groundwater 

in these wells had apparent ages of 15,625–39,350 years. 

Measured 14C activities in samples from Bicycle Basin 

ranged from about 0.7 to 14.3 pmC. The highest 14C activity 

(14.3 pmC) was measured in groundwater from well 14N/3E24H1, along the eastern edge of the basin. The uncorrected 

14C data indicated that groundwater in this well was about 

15,625 years old. Lower 14C activities (less than 14 pmC) were 

measured in groundwater from wells throughout the basin.

The low 14C activities and the lack of measurable 3H 

indicated that Bicycle Basin had not received quantities of 

recent recharge sufficient to be detected in the groundwater 

samples collected for this study. Some groundwater recharged 

since 1952 could be present in shallower parts of the 

groundwater system than was sampled, but the absence of 

modern age tracers indicated that modern recharge has not 

yet reached monitoring and production wells deeper in the 

system. The age data support that the basin was recharged 

during a colder and wetter period near the end of the last North 

American glaciation that ended about 10,000 years ago.
40 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 13

South Coyote Canyon fault

Unnamed fault 1

North Bicycle Lake fault

Tiefort Mountain fault

Coyote Canyon fault zone

A’

B

B’

Unnamed fault 2

A

(2000)

13M4: <0.09/6.0

13M3: <0.09/6.4

13M2: <0.09/1.7

(2000)

14P1: <0.09/6.6

(1997)

22N1: <−0.05/12.1

(2010)

23B3: R-0.06/5.4

23B2: 0.22/1.7

23B1: R0.03/0.7

(1993)

23G1: <0.09/na

(2000)

24Q5: <0.09/6.1

24Q4: <0.09/8.1

24Q3: <0.09/2.8

24Q2: <0.09/4.2

24Q1: <0.09/4.2

(2000)

35C1: <0.09/11.5

35C2: <0.09/7.7

(2008)

18N1: R0.00/8.2

(1993)

24H1: na/14.3

22P1

Figure 13 Map showing the location of wells, and Tritium and Carbon-14 in Bicycle Basin, Fort Irwin National

Training Center, California

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

(2011)

26K3: <0.09/6.9

26K4: R-0.09/11.3

26K1:<0.09/10.8

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

EXPLANATION

(2000)

35C1: <0.09/11.5

Bicycle groundwater basin Well type and identifier (see table 1)

Section A–A’

Section B–B’

Fault

Model inferred fault

Township/range

Year of measurement

Well identifier (see table 1)

Tritium, in tritium units

Carbon-14, in percent modern carbon

Well labels

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

22P1

23G1

14P1

23B3

24H1

Figure 13. Tritium and carbon-14 activities for groundwater from selected wells, Bicycle Basin, Fort Irwin National Training Center, 

California.
Groundwater-Flow Model 41

Groundwater-Flow Model

Groundwater-flow models were developed for the 

Irwin, Langford, and Bicycle Basins, which supply water to 

the NTC, to better understand the aquifer systems and the 

potential effects of groundwater pumping, and for use as tools 

to help manage groundwater resources at NTC (fig. 14). The 

groundwater-flow model of the Irwin Basin, which underlies 

most of the Fort Irwin garrison, originally was described by 

Densmore (2003) and subsequently was updated by Voronin 

and others (2014). In addition, a groundwater-flow model was 

developed for the Langford Basin to the south (Voronin and 

others, 2013). This report documents the groundwater-flow 

model for the Bicycle Basin.

The Bicycle Basin model was constructed using 

MODFLOW-NWT (Niswonger and others, 2011). 

MODFLOW-NWT is a finite-difference model that simulates 

groundwater flow in three-dimensional heterogeneous and 

anisotropic media. The MODFLOW-NWT packages included 

in model development were the Basic (BAS; Harbaugh, 

2005), Upstream Weighting (UPW; Niswonger and others, 

2011), Drain (DRN; Harbaugh, 2005), Horizontal-Flow 

Barrier (HFB6; Hsieh and Freckleton, 1993), Recharge (RCH; 

Harbaugh, 2005), Multi-Node Well 2 (MNW2; Konikow 

and others, 2009), and Subsidence and Aquifer-System 

Compaction package (SUB; Hoffmann and others, 2003) 

with the Newton formulation (NWT) solver (Niswonger and 

others, 2011). 

Model Discretization

Discretization of the model domain was based on 

geohydrologic data collected by previous investigators 

(Densmore, 2003; Voronin and others, 2013) and for this 

study. To numerically solve for the distribution of hydraulic 

heads in the aquifer system, it was necessary to discretize the 

system spatially and temporally. For this study, the model 

units were feet and days. Annual results are presented in 

calendar years.

Spatial Discretization

The Bicycle Basin model is discretized spatially 

using a rectangular grid with uniform grid spacing and is 

contained within a regional grid with the same grid spacing. 

The regional grid is large enough to include the Irwin, 

Langford, and Bicycle Basins, so the models of these basins 

can be incorporated into one model that can be used to help 

the NTC manage water resources on a regional basis. The 

grid-cell size is 500-ft by 500-ft with a total of 49 rows and 

63 columns. There are 5,980 active model cells in 8 model 

layers (figs. 15, 16). The active area of the model varied with 

depth, with model layer 8 having the least number (537) 

of active model cells. Model layers 4–8 were not present 

southwest of unnamed fault 1 because the basement complex 

is shallow in that part of the basin. The model was divided 

into parameter zones (figs. 15A–H) for parameterization of 

hydraulic properties, which is described in the “Parameter 

Zonation” section of this report. The hydraulic properties are 

homogeneous in each model cell.

Land-surface altitudes for each cell in model layer 1 

were estimated from a 33-ft (10-m) digital elevation model 

(DEM; U.S. Geological Survey, 2000; https://nationalmap.

gov/elevation.html). The bottom altitudes of the model layers 

at the production and monitoring wells were determined from 

lithologic logs and borehole geophysical data. These altitudes 

were interpolated to the model grid and were flattened near 

the edges of the basin where the stratigraphic units are steeply 

dipping, which caused numerical instabilities of the model; 

consequently, the layer boundaries did not correspond to the 

stratigraphic boundaries in all parts of the basin. The basement 

complex altitudes were derived from gravity data (fig. 4) 

and extrapolated to the model grid to determine the bottom 

altitude of model layer 8 northeast of unnamed fault 1 and 

the bottom altitude of model layer 3 southwest of the fault. 

An altitude of 1,400 ft was assigned to cells of the lowest 

model layer where the basement complex was at a lower 

altitude. Because well data were not available at or below 

this depth, and the general observation was that the alluvial 

deposits are more consolidated and yield less water at depth, 

an altitude of 1,400 ft was assumed to be below the active 

groundwater-flow system.

The vertical layering in the model along cross sections 

is shown in figures 16A–B. Locations of these sections are 

shown in figure 15A. The distribution of thickness for each 

model layer is shown in figures 17A–H. For model layer 1, the 

thickness was calculated by subtracting the bottom altitude 

of the layer from the land surface. For the underlying model 

layers, the thickness was calculated by subtracting bottom 

altitudes of the layer from the bottom altitude of the overlying 

layer. The thickness of each model layer is variable, and the 

range is given in table 6.

In general, model layers 1–6 represent the upper aquifer, 

and models layers 7 and 8 represent the lower aquifer. Model 

layers were mostly flat lying and cut across stratigraphic 

units, but were delineated to highlight vertical differences 

in hydraulic properties related to stratigraphic units. The 

textural variations in stratigraphic units in model layers were 

reflected in variations in hydraulic properties, described in the 

“Aquifer System Definitions” section. Model layer 1 generally 

represents the Quaternary younger alluvium (Qya) and older 

alluvium (Qoa) and the Quaternary-Tertiary older alluvium 

(QToa), although the Quaternary playa deposits (Qp) also 

are represented in model layer 1 in the southern part of the 

basin (figs. 16A–B). Model layer 1 is thickest in the eastern 

part of the basin in parameter zone 1 (fig. 17A). Model layer 

2 represents the Quaternary-Tertiary older alluvium (QToa), 

with older clay lacustrine deposits (QTol) present to a limited 

extent in the southern part of the basin (figs. 16A–B). Model 

layer 2 is thickest in the southwestern part of the basin 
42 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 14. Location of local and regional groundwater-flow model grids, Fort Irwin National Training Center, California.

sac11-0424_fig 14

0 2 4 6 8 MILES

0 2 4 6 8 KILOMETERS

116°50’ 116°40’

35°

30’

35°

20’

35°

10’

Granite Mts

Tiefort Mts

Ft. Irwin

National

Training 

Center

EXPLANATION

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

Fort Irwin National Training Center

boundary 

Regional model grid with row Dry lakes

 and column numbers in black

Irwin Basin model grid (Densmore, 

 2000; Voronin and others, 2014)

Langford Basin model grid

 (Voronin and others, 2013)

Bicycle Basin model grid with row

 and column numbers in red 

1

1

25

50

75

100

125

150

25 50 75 100 125

1

1

49

63
Groundwater-Flow Model 43

Figure 15. Active model cells, parameter zones, wells perforated in each layer, recharge cells (model layer 1 only), drain cells (model 

layer 1 only), and modeled faults for Bicycle Basin, Fort Irwin National Training Center, California: A, model layer 1; B, model layer 2; 

C, model layer 3; D, model layer 4; E, model layer 5; F, model layer 6; G, model layer 7; and H, model layer 8.

sac11-0424_fig 15ab

22P1

23G1

13K1

24H1

23B3

14H1

26K1

EXPLANATION

5

6

7

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

4

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well screened in layer 2 and 

 identifier (see table 1)

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

Layer 1

13

D

D DDD D

1 1

2

1 13

5 4

2

5

2

13

12

7

2

3

1

8 8

7

7

9

1

12

2

1

7

1

7 7

1

1 2

6

4

1

9

1

3

3

13

1 9

12

13

1

5

7

7

88

13

8

2

1

2

6

1

1

7

9

1

8

7

2

12

8 8

1

7

13

8

1

12

2

1

4

1

1

6

1

8

7

2

7

11

11

11

11

1010 10

10

10

22P1

23G1

13K1

24H1

A EXPLANATION

R. 3 E. R. 4 E.

T.

14

N.

A

A’

B

B’

5

6

7

Bicycle groundwater basin

Model boundary

Recharge cells and recharge-

 zone number

Drain cells

Model grid

Modelled horizontal flow barrier

Section A–A’

Section B–B’

Township/range

D D

1

2

3

4

Parameter zones

1 1

116°40’ 116°38’ 116°36’

35°18’ 35°16’

B

13

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Destroyed

Test well

Obstructed

Well screened in layer 1 and 

 identifier (see table 1)

13K1

23G1

22P1

13K1

23G1

24H1

26K1

24H1

24H1

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, Zone 11

North American Datum of 1983

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

No-flow

boundary

No-flow

boundary
44 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 15. —Continued

sac11-0424_fig 15cd

C

D

No-flow

boundary

No-flow

boundary

13K1

23G1

24H1

24Q5

13K1

23G1

22P1

13M4

24H1

22P1

23G1

13K1

24H1

14H1 13M1

13M4

26K1

26K3

24Q5

18N1

18N2

23G1

13K1

24H1

14H1

13M1

24Q5

18N1 14P2

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

0 0.5 1 MILE

0 10.5 KILOMETER

EXPLANATION

5

6

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Test well

Obstructed

Wells screened in layer 4 and 

 identifier (see table 1)

EXPLANATION

5

6

7

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

4

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Wells screened in layer 3 and 

 identifier (see table 1)

23B3

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault
Groundwater-Flow Model 45

Figure 15. —Continued

sac11-0424_fig 15ef

E

F

No-flow

boundary

No-flow

boundary

13K1

23G1

24Q4

13K1

24H1

23G1

13M3

23G1

13K1

24H1

14H1 13M1

13M3

18N1

14P2

14P1

23G1

13K1 14H1 13M1

13M3

18N1 14P1

24Q4

23B2

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

116°40’ 116°38’ 116°36’

35° 18’ 35° 16’

R. 3 E. R. 4 E.

T.

14

N.

0 0.5 1 MILE

0 10.5 KILOMETER

EXPLANATION

5

6

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Test well

Obstructed

Well screened in layer 5 and 

 identifier (see table 1)

EXPLANATION

5

6

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Test well

Well screened in layer 6 and 

 identifier (see table 1)

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault
46 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 15gh

No-flow

boundary

No-flow

boundary

EXPLANATION

5

6

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

1

2

3

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Test well

Well screened in layer 7 and 

 identifier (see table 1)

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Modelled horizontal flow barrier

Township/range

Parameter zones

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Production

Multiple-well monitoring site

Test well

Well screened in layer 8 and 

 identifier (see table 1)

5

6

1

2

3

13K1

23G1

13M2

18N1

23G1

24Q2

23G1

13K1 14H1 13M1

13M2

18N1

24Q3

23B1

23G1

18N1

24Q1, 2

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

G

H

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

Figure 15. —Continued
Groundwater-Flow Model 47

Figure 16. Cross-sectional view across Bicycle Basin, Fort Irwin National Training Center, California, showing generalized geologic 

sections and model layers along A, A–A’ and B, B–B’.

sac11-0415_Figure 16a

Unnamed

fault 1

North Bicycle

Lake fault

35C2, 3

(projected)

26K1, 3, 4

13M2, 3, 4 23G1 23B1, 2, 3

South Coyote

Canyon fault

Coyote

Canyon

fault

Model

boundary

Model

boundary

Parameter

zone 6 BEND IN SECTION

Parameter

zone 2

BEND IN

SECTION

PART OF

SECTION

B–B’

BEND IN

SECTION

Unnamed

fault 2

Parameter

zone 4

ML 1

ML 3

ML 2

ML 1

ML 2 ML 3

ML 4

ML 6 ML 5

ML 8

ML 7

EXPLANATION

Geologic unit/age

Qoa

QToa

Tog

QTol

Tyg

Bc

Playa/Quaternary

Younger alluvium/Quaternary

Older alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

Older clay lacustrine/ Quaternary-Tertiary

Younger alluvial gravels/Tertiary

Older alluvial gravels/Tertiary

Basement complex

Fine-grained deposits

Weathered or fractured deposits

Qya

Qp

Bottom of model layer (ML)

 and identifier

ML1

ML2

ML3

ML4

ML5

ML6

ML7

ML8

VERTICAL SCALE GREATLY EXAGGERATED

NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD 88)

Model boundary

Faults

Water table

Well and identifier

 (see table 1)

Perforated interval

23G1

SOUTH

FEET

NORTH

FEET

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

SECTION A–A’

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

A Aʹ

A
48 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 16. —Continued

sac11-0415 fig16b

Unnamed

thrust fault

SECTION B–B’

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

3,000

2,500

2,000

1,500

1,000

500

NAVD

88

B Bʹ

24Q1, 2, 3, 4, 5 23G1 14P1

23B1, 2 , 3

ML 1

ML 8

ML 7

ML 6

ML 5

ML 4

ML 3

ML 2

Model

boundary

Model

boundary

Parameter

zone 2

Parameter

zone 5

Parameter

zone 6

BEND IN

SECTION

PART OF

SECTION

A–A’

BEND IN

SECTION

South Coyote

Canyon fault

EXPLANATION

Model boundary

Faults

Water table

Geologic unit/age

Qoa

QToa

Tog

QTol

Tyg

Bc

Playa/Quaternary

Younger alluvium/Quaternary

Older alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

Older clay lacustrine/ Quaternary-Tertiary

Younger alluvial gravels/Tertiary

Older alluvial gravels/Tertiary

Basement complex

Fine-grained deposits

Weathered or fractured deposits

Qya

Qp

Bottom of model layer (ML)

 and identifier

ML1

ML2

ML3

ML4

ML5

ML6

ML7

ML8

VERTICAL SCALE GREATLY EXAGGERATED

NORTH AMERICAN VERTICAL DATUM OF 1988 (NAVD 88)

Well and identifier

 (see table 1)

Perforated interval

23G1

SOUTHEAST NORTHWEST

FEET FEET

B
Groundwater-Flow Model 49

Figure 17. Thickness of model layers in the groundwater-flow model for the Bicycle Basin, Fort Irwin National Training Center, 

California: A, 1; B, 2; C, 3; D, 4; E, 5; F, 6; G, 7; and H, 8.

sac11-0424_fig 17ab

No-flow

boundary

No-flow

boundary

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11

North American Datum of 1983

A

B 116°40’ 116°38’ 116°36’ 35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

>25 to 50

>50 to 75

>75 to 100

>100 to 150

Thickness (layer 1), in feet

>150 to 200

>200 to 250

>250

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

0 to 25

>25 to 50

>50 to 75

Thickness (layer 2), in feet

>75 to 100

>100 to 150

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Zone 1

Zone 1

Zone 1

Zone 2

Zone 3

Zone 4 Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Layer 1

Layer 2

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault
50 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 17. —Continued

sac11-0424_fig 17cd

No-flow

boundary

No-flow

boundary

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital

data; various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

C

D

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E. 

T.

14

N.

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

zone identifier

Simulated fault

Township/range

0 to 25

>25 to 50

>50 to 75

Thickness (layer 3), in feet

>75 to 100

>100 to 150

EXPLANATION

0 to 25

>25 to 50

Thickness (layer 4), in feet

>50 to 75

>75 to 100

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Zone 1

Zone 1

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Layer 3

Layer 4

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault
Groundwater-Flow Model 51

sac11-0424_fig 17ef

No-flow

boundary

No-flow

boundary

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

E

F

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

EXPLANATION

0 to 25

>25 to 50

Thickness (layer 5), in feet

>50 to 75

>75 to 100

EXPLANATION

>25 to 50

>50 to 75

>75 to 100

Thickness (layer 6), in feet

>100 to 150

>150 to 200

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Zone 1

Zone 1

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Layer 5

Layer 6

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

Figure 17. —Continued
52 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 17gh

No-flow

boundary

No-flow

boundary

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

G

H

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E. 

T.

14

N.

EXPLANATION

>25 to 50

>50 to 75

>75 to 100

>100 to 150

Thickness (layer 7), in feet

>150 to 200

>200 to 250

>250

EXPLANATION

>25 to 50

>50 to 75

>75 to 100

>100 to 150

Thickness (layer 8), in feet

>150 to 200

>200 to 250

>250

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Zone 1

Zone 1

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Layer 7

Layer 8

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

South Coyote Canyon fault

Unnamed fault 1

Bicycle Lake fault zone

Tiefort Mountain fault

Coyote Canyon fault zone

Unnamed fault 2

North Bicycle Lake fault

Figure 17. —Continued
Groundwater-Flow Model 53

(fig. 17B). Model layers 3–5 represent the Quaternary-Tertiary 

lacustrine deposits (QTol), primarily in parameter zone 6 

where land-surface has subsided, which grade to QuaternaryTertiary older alluvium (QToa) to the north and QuaternaryTertiary older alluvium (QToa) and Tertiary younger alluvial 

gravels (Tyg) to the south. Model layer 3 is thickest southwest 

of unnamed fault 1 in parameter zones 4 and 7 (fig. 17C); 

model layer 4 is thickest in the southeastern part of the basin 

in parameter zone 5 (fig. 17D); and model layer 5 is thickest 

north of the South Coyote Canyon fault in parameter zone 2 

(fig. 17E). Model layer 6 primarily represents the QuaternaryTertiary older alluvium (QToa), with Tertiary younger gravels 

(Tyg) present in the southern part of the basin and north of the 

South Coyote Canyon fault (figs. 16A–B). Model layer 6 is 

thickest in the north and central parts of the basin in parameter 

zones 1–3 and 6 (fig. 17F). Model layers 7 and 8 primarily 

represent the Tertiary younger and older gravel (Tyg and Tog) 

units, respectively (figs. 16A–B). Model layer 7 is thickest in 

the northern part of the basin in parameter zones 2, 3, and 6 

(fig. 17G), and model layer 8 is thickest in the southern part of 

the basin in parameter zones 5 and 6 and in the eastern part in 

parameter zone 1 (fig. 17H).

Temporal Discretization

For this study, the model simulated steady-state as well 

as transient conditions. There were 342 stress periods of 

varying length. The first stress period represented steadystate (predevelopment) conditions before 1967. Because 

sufficient water-level data were not available from before 

1967, the initial conditions for the steady-state stress period 

were determined from the first water-level measurements 

in 20 wells described in the “Groundwater Altitudes and 

Movement” section. The steady-state stress period had one 

time step. The simulated heads at the end of the steady-state 

stress period were the initial heads for the transient simulation 

period. Stress periods 2–18 were 1 year in duration and 

represented transient conditions for 1967–83. Stress periods 

19–342 were each 1 month in duration to represent the 

variability in pumping for 1984–2010. Each transient stress 

period had six time steps.

Model Boundaries

The boundaries of the Bicycle Basin groundwaterflow model (fig. 15) were determined by the geohydrologic 

interpretations discussed in the “Geohydrologic Framework” 

section of this report and generally coincided with the 

boundaries of the aquifer system. The top boundary of the 

model, the water table, was simulated as a free-surface 

boundary, which is allowed to move vertically in response 

to changes in inflow, outflow, and storage of water in the 

aquifer. No-flow boundaries were specified laterally around 

the modeled domain (fig. 15) to represent contact with 

low-permeability volcanic and crystalline basement rocks 

(basement complex) and for the lower boundary (fig. 16) 

to represent Tertiary older gravels (Tog) deep in the basin 

and the basement complex south of the unnamed fault 1; 

these sediments and rocks were assumed to yield little to no 

water. A no-flow boundary indicates no exchange of water 

between model cells along the boundary and the area outside 

the model. 

A drain was used along the southern boundary of the 

basin (fig. 15A) to simulate natural groundwater discharge 

through fractured volcanic material and granitic bedrock 

southeast of the Bicycle Lake (dry) playa (see “Hydrologic 

Framework” section). Drain boundary conditions were 

assigned to six cells in model layer 1 along part of the 

southern boundary of Bicycle Basin (fig. 15A). Discharge 

through the drain is controlled by the calibrated altitude of the 

drain relative to the simulated hydraulic head in the aquifer 

and by the calibrated hydraulic conductance between the 

aquifer and the drain. These characteristics are discussed in the 

“Simulation of Natural Recharge and Discharge” section of 

this report.

Table 6. Model-layer thickness in the groundwater flow model of 

Bicycle Basin, Fort Irwin National Training Center, California.

Layer Thickness 

(feet)

1 43–275

2 9–105

3 22–111

4 19–88

5 20–83

6 26–153

7 30–338

8 41–551
54 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Model Input

Input required for this model included hydraulic 

properties, recharge, discharge, and pumpage. Hydraulic 

properties included horizontal and vertical hydraulic 

conductivity for each model parameter zone (fig. 15), specific 

yield in model layers 1–6, specific storage in model layers 2–8, 

elastic and inelastic specific storage and preconsolidation 

heads (necessary to simulate subsidence), and the hydraulic 

characteristic (associated with faults that act as horizontal flow 

barriers). Input values for hydraulic conductivity and specific 

storage are used to calculate transmissivity and storage 

coefficient values, respectively, in the model. Parameter zones 

(fig. 15) were defined on the basis of the spatial geometry of 

the active model domain from interpretations of surface and 

subsurface geology described earlier in this report. Recharge 

estimates were based on a subset of the BCM developed by 

Flint and others (2004). Pumpage data were provided by Fort 

Irwin personnel (Christopher Woodruff, written commun., 

2010). The hydraulic characteristic values were estimated for 

individual fault segments during model calibration.

Hydraulic Properties

Hydraulic properties assigned to model cells (horizontal 

and vertical hydraulic conductivity, specific yield, and specific 

storage) affect the simulated rate at which groundwater moves 

through an aquifer, the volume of water in storage, and the rate 

and areal extent of water-level changes caused by groundwater 

pumping and recharge. Hydraulic properties associated with 

subsidence (elastic and inelastic specific storage) affect the 

rates of aquifer deformation, manifested as land subsidence, 

attributable to dewatering of interbedded fine-grained silts and 

clays. Horizontal hydraulic conductivity, vertical anisotropy 

ratio, specific yield, and specific storage were specified in 

the Upstream-Weighting (UPW package; Niswonger and 

others, 2011). Elastic and inelastic specific storage and 

preconsolidation heads were specified in the Subsidence 

and Aquifer-System Compaction (SUB package; Hoffman 

and others, 2003). Trial-and-error and automated parameterestimation methods were both used during the modelcalibration process to estimate the final hydraulic properties 

given in subsequent sections; this process is discussed in the 

“Model Calibration” section of this report.

Parameter Zonation

Parameter zonation was used because the number 

and distribution of wells with detailed lithologic and 

borehole geophysical data to adequately represent complex 

heterogeneity of the hydraulic properties in the aquifer 

system were insufficient. Parameter zones (figs. 15A–H) were 

defined on the basis of the horizontal and vertical distribution 

of stratigraphic units described in the “Geologic Units” 

section and on horizontal-flow barriers (faults); the resulting 

zones were used to distribute hydraulic properties to model 

cells. Parameter zones 1–5 and 7 include parts of the basin 

beyond the lateral extent of the buried lacustrine deposits 

(QTol) north and northwest of the Bicycle Lake (dry) playa 

(fig. 16). In addition, the South Coyote Canyon fault separates 

parameter zone 2 from the rest of the basin, and parameter 

zones 4 and 7 are southwest of the unnamed fault 1. The 

surface expression of the Quaternary older alluvium (Qoa) 

geologic unit distinguishes parameter zone 7 from parameter 

zone 4, which includes Quaternary younger alluvium (Qya) 

and the Bicycle Lake (dry) playa at land surface. Parameter 

zone 6 was defined by the lateral extent of the QuaternaryTertiary lacustrine deposits (QTol) geologic unit and landsurface deformation determined from analysis of InSAR 

images described in the “Land-Surface Deformation” section. 

Parameter zones 1–3 and 5–6 are in all layers; parameter 

zones 4 and 7 are only in layers 1–3 (table 7) because the 

basement complex is shallow in this part of the basin. The 

hydraulic-property distributions for these parameter zones 

were input to the UPW package (Niswonger and others, 2011) 

in MODFLOW-NWT. The UPW package calculates all terms 

in the numerical formulation of the groundwater-flow equation 

and is an alternative to the block-centered flow, layer-property 

flow, and hydrogeologic unit flow packages (Niswonger and 

others, 2011).

Table 7. Number of hydraulic-parameter zones in model 

layers 1–8 of the Bicycle Basin groundwater-flow model, Fort 

Irwin National Training Center, California.

Layer Number of parameter zones1

1 7

2 7

3 7

4 5

5 5

6 5

7 5

8 5

Total 46

1

Vertical anisotropy ratio (VANI) and specific storage (SS) were not zoned 

in layer 8.
Groundwater-Flow Model 55

Hydraulic Conductivity

Initial estimates of horizontal hydraulic conductivity 

(HK) values for the unconsolidated deposits, based on 

previous modeling studies (Densmore, 2003; Voronin and 

others, 2014), aquifer test results, and geologic interpretations 

for this study or published values for lithologic categories 

(Bouwer, 1978; Freeze and Cherry, 1979; Fetter, 1994), 

are summarized for each parameter zone in table 8. These 

estimates served as starting points for the calibration process. 

Initial HK values ranged from 0.1 ft/d in model layers 3–5 

of parameter zones 3 and 6 to 15 ft/d in model layers 1–6 of 

parameter zones 1, 2, and 5; model layer 1 in zone 4 and 7; 

and model layer 6 in zones 3 and 6 (table 8). One HK value 

was calibrated for each of the parameter zones in each model 

layer. Final calibrated HK values ranged from 0.04 ft/d for 

the Quaternary-Tertiary older alluvium (QTol) geologic 

unit in model layer 5 of parameter zone 6 to 33 ft/d for the 

predominantly unconsolidated coarse-grained unit represented 

by model layer 6 of parameter zone 6 (table 8).

The HK values for the upper aquifer (model layers 1–6) 

estimated from specific-capacity data at selected wells 

ranged from 3 to 35 ft/d (table 2). The average calibrated 

HK values for the model layers representing the perforated 

intervals for these wells ranged from 5.2 to 17 ft/d. The HK 

value from the specific capacity test for well 14N/4E-18N1 

(3 ft/d, in zone 1) reflects, at least partially, the properties 

of the lower aquifer. The calibrated HK values for layers 7 

and 8 (0.63 ft/d and 0.34 ft/d, respectively), which represent 

the lower aquifer, are considerably less than this value. As 

mentioned in the “Aquifer System Definitions” section, HK 

values were determined from slug tests in wells 14N/3E-26K4 

(model layer 2) and 14N/3E-26K1 (model layer 3), which are 

in parameter zone 4. The calibrated HK values for parameter 

zone 4 (30 ft/d for model layer 2 and 7.0 ft/d for model 

layer 3) agreed reasonably with the measured data (28 ft/d for 

14N/3E-26K4 and 6.78 ft/d for 14N/3E-26K1).

The vertical hydraulic conductivity (VK) for each model 

layer is computed in the model by dividing the HK values 

by vertical anisotropy (VANI), where VANI is defined as the 

ratio of HK to VK. For example, a VANI of 10 means that the 

HK is 10 times greater than the VK. An initial VANI value 

of 100 was assumed for all model layers in all parameter 

zones; however, VANI values typically are unknown and are 

estimated through model calibration (Anderson and Woessner, 

1992). The final VANI values ranged from 2, in model 

layer 4 of parameter zone 2 and model layer 5 in parameter 

zone 5, to 22,255, in model layer 1 of parameter zone 6 

(table 8). Although these values span a large range, layered 

heterogeneity frequently can lead to regional anisotropy 

of 100:1 or greater (Freeze and Cherry, 1979). The final 

computed values of VK ranged from 2.9×10–6 ft/d in model 

layer 5 of parameter zone 6 to 7.1 ft/d in model layer 4 of 

parameter zone 3 (table 8). 

Vertical conductivity values were determined from 

analysis of cores from the borehole for wells 14N/3W23B1–3 (see the “Aquifer System Definitions” section), 

which is in parameter zone 6 (fig. 15). These values were 

9.0×10–4 ft/d for the Quaternary-Tertiary lacustrine deposits 

(QTol; represented by model layers 3–5), 1.0×10–2 ft/d for 

the Tertiary younger gravels (Tyg; represented by model 

layer 7), and 4.0×10–4 ft/d for the Tog (represented by model 

layer 8). The VK value calculated from the calibrated values 

for HK and VANI in model layer 3 for parameter zone 

6 (8.17×10–4 ft/d) was similar to the measured data. The 

VK values calculated for model layers 7–8 (table 8) were 

considerably less than the measured data. The discrepancies 

can be attributed to prioritizing calibration to measured water 

levels and to observed land-surface deformation rather than 

to the VK data in parameter zone 6, which are from core 

samples representing short intervals of a single borehole in 

heterogeneous sediments.

Specific Yield and Specific Storage

Specific yield (SY) is defined as the volume of water 

released from storage in an unconfined (water table) aquifer 

by unit surface area of the aquifer for each unit decline in 

head (Lohman, 1972). The specific storage (SS) is the volume 

of water that a unit volume of aquifer releases from storage 

for a unit decline in hydraulic head in a confined aquifer 

(Freeze and Cherry, 1979). The SY, which represents gravity 

drainage following a decline in the water table, is typically 

orders of magnitude greater than the SS and is the dominant 

storage parameter volumetrically for each unit thickness of 

aquifer material.

In MODFLOW-NWT, model-layer types are assigned 

as convertible or confined. A model layer is converted from 

confined to unconfined conditions when the hydraulic head 

in the layer falls below the top of the layer. For this study, 

model layers 1–6 were convertible, and model layers 7 and 

8 were confined. Accordingly, SY and SS were defined for 

model layers 1–6; one or the other was used, depending on the 

simulated hydraulic head during each stress period. 

During calibration of the transient model, values of SY 

were estimated for each of the parameter zones in model 

layers 1–6. Similarly, SS was estimated for each parameter 

zone in model layers 1–8. An initial SY value of 0.10 was 

assigned to model layers 1–6 in all zones (table 8). This value 

has been used for other desert basins (Rewis and others, 2006; 

Voronin and others, 2013) and is within the range of specific 

yield estimates from aquifer tests completed for this study 
Table 8. Summary of initial and final parameter estimates used in the groundwater-flow model of Bicycle Basin, Fort Irwin National Training Center, [Vertical anisotropy, the ratio of horizontal to vertical hydraulic conductivity; vertical hydraulic conductivity is calculated by HK/VANI. Abbreviations: NA, no value; —, not a

Model layers Parameter zone 1 2 3 4 5 6 

Initial Final Initial Final Initial Final Initial Final Initial Final Initial Final 

Horizontal hydraulic conductivity (HK), feet per day 1 15 29 15 1.6 1.0 23 15 7.1 15 32 1.0 3.5 

2 15 20 15 2.0 1.0 1.3 10 30 15 9.8 1.0 18 

3 15 20 15 6.5 0.10 1.6 1.0 7.0 15 9.2 0.10 0.92 

4 15 10 15 4.0 0.10 19 NA NA 15 1.0 0.10 0.06 5 15 8.3 15 14 0.10 3.5 NA NA 15 3.9 0.10 0.04 6 15 0.81 15 1.7 15 15 NA NA 15 8.8 15 33 

7 10 0.63 10 2.8 10 5.350 NA NA 10 0.14 10 0.13 8 1.0 0.34 1.0 0.78 1.0 5.2 NA NA 1.0 0.13 1.0 0.10 

Vertical anisotropy (VANI), unitless 1 100 2,874 100 1,263 100 6.3 100 5,255 100 64 100 22,255 

2 100 1,123 100 122 100 39 100 94 100 3.9 100 18 

3 100 997 100 83 100 68 100 22 100 33 100 1,123 

4 100 28 100 2.0 100 2.61 NA NA 100 56 100 1,499 

5 100 14 100 548 100 26 NA NA 100 2.0 100 13,806 

6 100 57 100 5,914 100 11 NA NA 100 57 100 10,169 7 100 1,325 100 3,772 100 5,770 NA NA 100 16,592 100 2,944 8 100 11,730 100 11,730 100 11,730 NA NA 100 11,730 100 11,730 

Vertical hydraulic conductivity (VK), feet per day 1 0.15 0.01 0.15 1.3E–03 0.01 3.6 0.15 1.4E–03 0.15 0.50 0.01 1.6E

2 0.15 0.02 0.15 0.02 0.01 0.03 0.10 0.32 0.15 2.5 0.01 0.99 

3 0.15 0.02 0.15 0.08 1.0E–03 0.02 0.01 0.31 0.15 0.28 1.00E–03 8.2E

4 0.15 0.37 0.15 2.02 1.0E–03 7.1 NA NA 0.15 0.02 1.00E–03 3.9E5 0.15 0.60 0.15 0.03 1.0E–03 0.13 NA NA 0.15 2.0 1.00E–03 2.9E6 0.15 0.01 0.15 3.0E–04 0.15 1.4 NA NA 0.15 0.15 0.15 3.2E7 0.10 4.8E–04 0.10 7.3E–04 0.10 9.3E–04 NA NA 0.10 8.2E–06 0.10 4.3E8 0.01 2.9E–05 0.01 6.7E–05 0.01 4.4E–04 NA NA 0.01 1.1E–05 0.01 8.7E
Model 

layers

Parameter zone

1 2 3 4 5 6 

Initial Final Initial Final Initial Final Initial Final Initial Final Initial Final 

Specific yield (SY), unitless

1 0.10 0.12 0.10 0.19 0.10 0.23 0.10 0.12 0.10 0.13 0.10 0.10 

2 0.10 0.14 0.10 0.19 0.10 0.07 0.10 0.07 0.10 0.12 0.10 0.01 

3 0.10 0.12 0.10 0.23 0.10 0.07 0.10 0.07 0.10 0.10 0.10 0.01 

4 0.10 0.23 0.10 0.23 0.10 0.07 0.10 NA 0.10 0.10 0.10 0.01 5 0.10 0.23 0.10 0.09 0.10 0.07 0.10 NA 0.10 0.10 0.10 0.01 6 0.10 0.10 0.10 0.05 0.10 0.05 0.10 NA 0.10 0.07 0.10 0.07 

Specific storage (SS), per foot

1 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E–06 1.0E

2 1.0E–06 9.0E–07 1.0E–06 8.6E–07 1.0E–06 2.5E–06 1.0E–06 8.7E–07 1.0E–06 2.0E–06 1.0E–06 9.8E

3 1.0E–06 3.2E–05 1.0E–06 3.9E–06 1.0E–06 8.1E–07 1.0E–06 2.1E–06 1.0E–06 8.6E–07 4.2E–07 4.2E

4 1.0E–06 3.6E–06 1.0E–06 4.1E–06 1.0E–06 9.0E–07 1.0E–06 NA 1.0E–06 9.0E–07 4.2E–07 4.2E

5 1.0E–06 4.2E–05 1.0E–06 4.9E–05 1.0E–06 1.6E–06 1.0E–06 NA 1.0E–06 8.7E–07 4.2E–07 4.2E

6 1.0E–06 1.3E–05 1.0E–06 7.7E–06 1.0E–06 1.3E–06 1.0E–06 NA 1.0E–06 1.7E–06 1.0E–06 9.7E

7 1.0E–06 1.3E–05 1.0E–06 8.6E–07 1.0E–06 8.4E–07 1.0E–06 NA 1.0E–06 8.3E–07 1.0E–06 9.0E

8 1.0E–06 5.0E–06 1.0E–06 5.0E–06 1.0E–06 5.0E–06 1.0E–06 NA 1.0E–06 5.0E–06 1.0E–06 5.0E

Subsidence parameters for parameter zone 6

Instantaneous compaction Delayed compaction

Model 

layers

Elastic skeletal 

specific storage (Ske), 

unitless

Inelastic skeletal 

specific storage (Skv), 

unitless

Vertical hydraulic 

conductivity (Kvi), 

feet per day

Elastic skeletal 

specific storage (Sske), 

per foot

Initial Final Initial Final Initial Final Initial Final 

2 — — — — 1.2E–06 1.2E–06 1.8E–05 1.1E–05 

3 1.8E–05 7.6E–06 1.8E–04 5.4E–05 — — — — 4 1.8E–05 4.1E–06 1.8E–04 6.7E–05 — — — — 5 1.8E–05 3.3E–06 1.8E–04 5.4E–05 — — — — 6 — — — — 1.2E–06 1.2E–06 1.8E–05 8.0E–06 

7 — — — — 1.2E–06 1.2E–06 1.8E–05 8.5E–06 

Table 8. Summary of initial and final parameter estimates used in the groundwater-flow model of Bicycle Basin, Fort Irwin National Training Center, [Vertical anisotropy, the ratio of horizontal to vertical hydraulic conductivity; vertical hydraulic conductivity is calculated by HK/VANI. Abbreviations: NA, no value; —, not a
58 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

(table 2). Initial SS values for all parameter zones in all layers, 

except layers 3–5 in parameter zone 6, were 1.0×10–6 ft–1. 

An initial SS value of 4.2×10–7 ft–1 (the compressibility of 

water) was used for parameter zone 6 in model layers 3–5, 

where there is deformation of fine-grained silts and clays; 

this value was not adjusted during calibration. The final SY 

values ranged from 0.01 in model layers 2–5 in parameter 

zone 6 and model layers 2–3 in zone 7 to 0.23 for model 

layers 4–5 in parameter zone 1, model layers 3–4 in parameter 

zone 2, and model layer 1 in parameter zone 3 (table 8). The 

final SS values ranged from 4.20×10–7 ft–1 in model layer 

3–5 of parameter zone 6 to 4.95×10–5 ft–1 in model layer 5 of 

parameter zone 2 (table 8).

Elastic and Inelastic Storage

Land subsidence in Bicycle Basin was simulated using 

the Subsidence and Aquifer-System Compaction (SUB) 

package (Hoffmann and others, 2003) to allow both for 

instantaneous and delayed drainage of the fine-grained 

deposits (interbeds) of model layers 2–7 in parameter zone 

6. The confining unit in Bicycle Basin consists primarily of 

thick, buried lacustrine deposits of the Quaternary-Tertiary 

lacustrine (QTol) geologic unit. In the Bicycle Basin model, 

model layers 3–5 represented the Quaternary-Tertiary 

lacustrine (QTol) confining unit. This unit was divided into 

three model layers of instantaneous compaction to increase the 

accuracy of simulated flow and storage changes (Leake and 

others, 1994). Model layer 2 primarily consists of interbedded 

sands and gravels of the Quaternary-Tertiary older alluvium 

(QToa) geologic unit (fig. 16). Model layer 6 consists of the 

Quaternary-Tertiary older alluvium (QToa) geologic unit and 

the sand and gravel deposits of the Tertiary younger gravel 

(Tyg) geologic unit (fig. 16A). Model layer 7 consists of the 

Tertiary younger gravel (Tyg) geologic unit, which grades 

laterally into fine-grained deposits (fig. 16B). Although the 

deposits in model layers 2, 6, and 7 are primarily coarsegrained, there can be delayed compaction where thin, lowpermeability, fine-grained deposits are present. 

The thicknesses of the fine-grained interbeds subject to 

instantaneous and delayed compaction were specified in the 

SUB package. Estimated storage properties associated with 

instantaneous compaction of fine-grained deposits include 

elastic and inelastic skeletal storage coefficient (Ske and Skv, 

respectively; unitless). Estimated storage properties associated 

with delayed drainage of fine-grained deposits include 

elastic and inelastic skeletal specific storage (Sske and Sskv, 

respectively; per ft). Preconsolidation heads (Hc) are specific 

for instantaneous and delayed compaction. The simulation 

of delayed compaction also required the vertical hydraulic 

conductivity associated with the interbeds (Kvi). 

The thickness of the fine-grained deposits in parameter 

zone 6 was estimated from the borehole geophysical data 

for monitoring wells 14N/3E-23B1–3 and lithologic logs 

for wells 14N/3E-14P2 and 14N/3E-23G1 (fig. 2). For the 

interbeds that compact instantaneously in model layers 3–5, 

the thickness was interpolated between the wells by using 

a nearest neighbor method. The thickness distributions for 

model layers 3–5 are shown in figures 18A–C, respectively. 

The thickness distribution of the interbeds that undergo 

delayed compaction for model layers 2, 6, and 7 is shown in 

figure 18D. Fine-grained deposits were omitted from model 

layer 6 in the vicinity of well 14N/3E-23G1 because the 

lithologic log for that well indicated predominantly coarsegrained deposits at this depth.

Initial estimates for Ske and Skv for instantaneous 

compaction were 1.8×10–5 and 1.8×10–4, respectively, in 

model layers 3–5 (table 8). These values were adjusted during 

model calibration, and the final values for Ske ranged from 

3.27×10–6 in model layer 5 to 7.58×10–6 in model layer 3. The 

final values for Skv ranged from 5.38×10–5 in model layer 3 

to 6.71×10–5 in model layer 4 (table 8). Initial values for Kvi, 

Sske, and Sskv for delayed compaction were 1.2×10–6 ft/d, 

1.8×10–5 ft–1, and 1.8×10–4 ft–1, respectively, in model layers 2, 

6, and 7. The Kvi values were insensitive to observations, 

and the initial values did not change. The Sske and Sskv 

values were adjusted during model calibration, and the final 

Sske values ranged from 8.00×10–6 ft–1 in model layer 6 to 

1.08×10–5 ft–1 in model layer 2; the final Sskv values ranged 

from 8.46×10–5 ft–1 in model layer 7 to 1.58×10–4 ft–1 in model 

layer 2 (table 8).

Preconsolidation Head

Preconsolidation head, Hc, was defined by Poland (1984) 

as “the maximum antecedent effective stress to which a 

deposit has been subjected, and which it can withstand without 

undergoing additional permanent deformation.” Once the 

hydraulic head in an interbed falls below the preconsolidation 

head, permanent inelastic compaction of that interbed occurs. 

A new Hc is calculated at the end of each transient time step, 

which is then used in the subsequent time step (Hoffmann and 

others, 2003). In this study, the Hc value for all layers with 

fine-grained deposits in parameter zone 6 was assumed to be 

2,226 ft, which was similar to the earliest measured water 

level (well 14N/3E-13K1 in 1955; fig. 7A). Simulated water 

levels declined to the preconsolidation head when pumping 

began in the mid-1960s; the initial Hc value was not adjusted 

during model.

Horizontal-Flow Barriers

The Bicycle Basin model used an updated version of the 

Horizontal Flow Barrier (HFB package (Hsieh and Freckleton, 

1993) for use with MODFLOW-NWT; the functionality of 

the HFB package was unchanged (Niswonger and others, 

2011). The HFB package simulates barriers or faults as thin, 

vertical, low-permeability geologic features situated between 

pairs of adjacent cells in the model grid that impede the 

horizontal flow of groundwater (Hsieh and Freckleton, 1993). 
Groundwater-Flow Model 59

sac11-0424_fig 18_L3,L4

R. 3 E. R. 4 E.

T.

14

N.

Layer 4

Point 1

Point 2

Point 3

23B1-3

14P1

Point 1

Point 2

Point 3

23B1-3

14P1

A

Layer 3

B

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

14P1

14P1

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

5

10

15

20

Compressible clay thickness (layer 3),

 in feet

25

30 to 34

35 to 38

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

7

12

17

25

Compressible clay thickness (layer 4),

 in feet

30

40 to 45

50 to 53

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

Zone 1

Zone 1

Subsidence observation

 point and identifier

Subsidence observation

 point and identifier

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6 Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6 Zone 7

23G1

23G1

No-flow

boundary

No-flow

boundary

Figure 18. Thickness of fine-grained deposits in parameter zone 6 for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California, for instantaneous compaction in A, model layer 3; B, model layer 4; and C, model layer 5; and delayed 

compaction in model layers 2, 6, and D, 7.
60 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 18. —Continued

sac11-0424_fig 18a_L5

R. 3 E. R. 4 E.

T.

14

N

Point 1

Point 2

Point 3

23B1-3

14P1

Point 1

Point 2

Point 3

23B1-3

14P1

14P1

14P1

116°40’ 116°38’ 116°36’

35°18’ 35°16’

R. 3 E. R. 4 E.

T.

14

N.

Layer 5

C

Layers 2, 6, and 7

D

116°40’ 116°38’ 116°36’

35°18’ 35°16’

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

0 0.5 1 MILE

0 10.5 KILOMETER

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

Model

layer 2

2

35

36

Compressible clay thickness (layer 2,

 6, and 7), in feet

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

Model

layer 6

0

25

24

Model

layer 7

1

55

18

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Township/range

5

10

15

20

Compressible clay thickness (layer 5),

 in feet

25

30 to 34

35 to 37

Zone 1

Zone 1

Subsidence observation

 point and identifier

Subsidence observation

 point and identifier

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6 Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

23G1

23G1

No-flow

boundary

No-flow

boundary
Groundwater-Flow Model 61

Groundwater flow across a simulated barrier is proportional to 

the hydraulic-head difference between adjacent cells, where 

the constant of proportionality is the hydraulic characteristic 

(Hchar, in d–1), which is defined as the hydraulic conductivity 

of the barrier divided by the distance across the barrier in the 

flow direction (Hchar = Kbarrier / Lbarrier).

The simulated faults were the South Coyote Canyon 

fault and two unnamed faults (fig. 15A). The locations and 

areal extents of faults in the basin were identified from the 

geologic analysis. During model calibration, it was determined 

that mapped faults next to and in the southwestern part of the 

basin needed to be extended (fig. 2) to match water levels 

better in that area. Additional analysis of the geologic and 

geophysical data determined that this change was justified. 

Initially, it was assumed that the faults were not important 

barriers to groundwater flow, and the Hchar value was set to 

1.0 d–1 for the horizontal-flow barriers in all layers (table 9). 

The Hchar values were adjusted in each model layer during 

model calibration to determine if the unnamed faults impeded 

lateral groundwater flow. The South Coyote Canyon fault was 

simulated separately for model layer 1; model layers 2–8 were 

grouped, because it was determined during model calibration 

that the fault was similarly restrictive to groundwater flow 

at these depths. This was supported by the water-level data 

for wells 14N/3E-13M1 and -14H1, which are north of the 

South Coyote Canyon fault and are perforated in model 

layers 2–7. The data indicated that when pumping was reduced 

or discontinued in these wells, water levels stabilized or rose. 

Water levels in similarly perforated wells in other parts of 

the basin, however, continued to decline (fig. 8), indicating 

little or no hydraulic connection across this fault. The Hchar 

value for each horizontal-flow barrier was calibrated to match 

measured drawdown throughout the calibration period. The 

final values represent the spatial variability of the estimated 

ability of these faults to restrict groundwater flow. The 

calibrated Hchar for the South Coyote Canyon fault indicated 

the fault was a restrictive barrier in model layers 2–8 and 

somewhat less restrictive in model layer 1. The final Hchar 

values ranged from 2.58×10–7 d–1 for the South Coyote Canyon 

fault in model layers 2–8 to 1.15 d–1 for the unnamed fault 1 

in model layer 1 (table 9), indicating the faults at most depths 

were more restrictive to groundwater flow than the initial 

value indicated. The calibrated Hchar value for unnamed 

fault 1 indicated the fault was not a restrictive groundwaterflow barrier in model layer 1; the final values for model 

layers 2 and 3 indicated the fault was somewhat restrictive 

in these layers (table 9). The calibrated Hchar values for 

unnamed fault 2 indicated the fault is less restrictive than 

unnamed fault 1 in model layers 2 and 3 and more restrictive 

in model layer 1 (table 9).

Simulation of Natural Recharge and Discharge

Recharge to the Bicycle basin was simulated using the 

Recharge (RCH) package. The BCM was used in this study 

to provide subsurface inflows and runoff along the margins of 

Bicycle Basin. Total recharge (subsurface inflow and runoff) 

was initially distributed to 95 cells in 11 recharge zones that 

represent the normally dry washes in the uppermost active 

model layers. Recharge zone 2 was subdivided into three 

separate recharge zones during model calibration, which are 

labeled 2, 12, and 13 on figure 15A. The recharge zones were 

based on the stream channels and washes that drain to the 

Bicycle Basin from adjacent watersheds (fig. 19). Subsurface 

inflow to the Bicycle Basin was simulated by the BCM at 

the boundary between Bicycle Basin and the surrounding 

mountain blocks. It was assumed that 100 percent of the 

calculated subsurface inflow recharged the Bicycle Basin. 

Runoff from the surrounding watersheds draining into 

the Bicycle Basin also was simulated by the BCM. It was 

assumed that 10 percent of the simulated runoff recharged 

the groundwater system. Izbicki and others (2002) indicated 

that about 10 percent of ephemeral streamflow in the southern 

Mojave Desert became recharge; hence, this value was used 

with the results of the BCM for the Bicycle groundwater basin. 

Table 9. Summary of initial and final hydraulic characteristics for 

horizontal-flow barriers in the groundwater-flow model of Bicycle 

Basin, Fort Irwin National Training Center, California.

[Units in 1/day]

Hydraulic characteristic (Hchar)

Initial Final

South Coyote Canyon fault

Layer 1 1.0 9.5E–03

Layers 2–8 1.0 2.6E–07

Unnamed fault 1

Layer 1 1.0 1.1E+00

Layer 2 1.0 9.7E–03

Layer 3 1.0 5.0E–03

Unnamed fault 2

Layer 1 1.0 3.9E–01

Layer 2 1.0 4.4E–01

Layer 3 1.0 8.7E–01
62 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Total recharge was assumed to be constant during the transient 

simulation period (1967–2010). Results from a study by 

Bouwer (1980) indicated that seasonal and annual fluctuations 

in infiltration were attenuated as a function of sediment 

particle size in the unsaturated zone and vertical distance 

to the water table. Bouwer (1980) found that downward 

velocities in the unsaturated zone decreased with decreasing 

particle size of the materials and that deep percolation 

virtually reaches a steady, uniform flow at a depth of about 

50–100 ft bls. Because the unsaturated zone mostly contains 

fine-grained sediment and the depth to water in the basin is in 

excess of 100 ft, a constant recharge rate in each recharge zone 

was a reasonable assumption. The initial recharge rate for each 

model cell in a recharge zone ranged from 1.98×10–6 ft/d in 

recharge zone 7 to 2.09×10–3 ft/d in recharge zone 2 (table 10). 

The recharge rates were parameterized and adjusted during 

model calibration. The final recharge rates for each model 

cell in a recharge zone ranged from 3.09×10–6 ft/d in recharge 

zone 7 to 2.99×10–3 ft/d in recharge zone 2 (table 10). Final 

recharge rates were higher than initial estimates for the areas 

recharged by the largest contributing watersheds (recharge 

zones 1 and 2; fig. 19). Final recharge rates were lower 

than initial estimates in most areas recharged by the smaller 

contributing watersheds (table 10).

Groundwater discharge was simulated using the 

MODFLOW Drain (DRN package (Harbaugh, 2005). 

Groundwater discharges to the drain cells near the southern 

boundary (fig. 15A) only when the simulated hydraulic head in 

the aquifer is greater than the drain altitude. Discharge in this 

part of the basin was inferred because (1) long-term runoff and 

recharge into the basin was greater than zero, (2) there were 

no outflows from the basin other than subsurface flow in the 

southeast, and (3) the estimated predevelopment water level 

was higher than the estimated bedrock elevation at this point. 

The initial drain altitude was assumed to be representative 

of the predevelopment water level in this area because it is 

the low spot in the basin. The earliest measured water level 

of 2,216 ft (fig. 7A) was assigned as the drain altitude in 

each of the six drain cells. This water level ranged from 117 

to 121 ft bls in these cells. The altitude was adjusted during 

model calibration, and the final value was 2,211 ft in each 

drain cell to match water levels better. Flow out of the drain 

also is controlled by the conductance between the aquifer 

and the drain. The initial drain conductance, 100 ft2

/d in each 

drain cell, was adjusted during model calibration so that the 

simulated recharge equaled the simulated discharge through 

the drain for the steady-state stress period. The final drain 

conductance was 4,335 ft2/d in each drain cell.

Groundwater Pumpage

The MODFLOW Multi-Node Well package, MNW2 

(Konikow and others, 2009) with the partial penetration option 

was used to simulate groundwater pumping from the five 

production wells in the Bicycle Basin. The MNW2 package 

simulates wells completed in multiple aquifers and allows 

vertical groundwater movement through the well bores. 

The groundwater-pumping rate at an individual well was 

distributed dynamically to model layers (multi-well nodes) on 

the basis of the hydraulic conductivity and the saturated length 

of the perforated interval in each layer. Initially, groundwater 

pumpage for each production well was distributed to 

perforated intervals in model layers 1–8, with only the 

perforated interval of production well 14N/3E-13K1 extending 

into model layer 1 (fig. 15A) and the perforated interval 

of production well 14N/4E-18N1 extending into layer 8 

(fig. 15H). Pumpage was redistributed to deeper perforations 

as the water table declined during the simulation period.

Annual and monthly pumpage compiled and estimated 

for this study was assigned to the active cell that contained the 

production well (fig. 15). Pumpage records included annual 

basin pumpage (not by well) for 1967–83 (table 3), annual 

pumpage by well for 1984–90 (fig. 6A; table 3), and monthly 

pumpage by well for 1991–2010 (fig. 6B). The ratio of average 

annual pumpage by well to total annual pumpage for the basin 

for 1984–86 was used to estimate the annual pumpage by well 

for 1967–83. The average ratio of monthly pumpage by well 

to total monthly pumpage for the basin for 1991–93 was used 

to estimate the monthly pumpage by well for 1984–90.

Table 10. Summary of initial and final groundwater–recharge 

values for the groundwater-flow model of the Bicycle Basin, Fort 

Irwin Training Center, California.

[Recharge rates are for each model cell in the recharge zone. See figure 15A

for location of recharge zones.]

Recharge 

zone2

Recharge1

Initial

(feet/day)

Final

(feet/day)

Difference

(percent)

1 7.30E–04 9.25E–04 27

2 2.09E–03 2.99E–03 43

3 2.77E–05 1.81E–05 –35

4 2.57E–06 4.62E–06 80

5 2.10E–05 2.70E–05 29

6 8.73E–06 4.11E–06 –53

7 1.98E–06 3.09E–06 56

8 2.10E–04 9.10E–06 –96

9 5.31E–04 4.85E–05 –91

10 4.76E–04 9.31E–05 –80

11 3.85E–04 3.42E–06 –99

12 NA3 3.42E–05 NA3

13 NA3 3.76E–06 NA3

1

Recharge is the sum of infiltration of runoff and watershed underflow.

2

Recharge zones numbers were based on the upstream watersheds shown in 

figure 19.

3

Recharge zones 12 and 13 originally were part of recharge zone 2; both 

were separated from zone 2 during model calibration.
Groundwater-Flow Model 63

sac11-0424_fig 19

Contributing watershed and identifier

 (see table 10 for inflow values)

Bicycle groundwater basin

0 1 2 3 4 5 MILES

0 1 2 3 4 5 KILOMETERS

Model boundary

Fort Irwin National Training Center boundary

Inflow point

2

1

3

4

4

5

6 7

8 9 10

11

116°50’ 116°40’

35°

25’

35°

20’

35°

15’

EXPLANATION

Ft. Irwin

National

Training 

Center

Base from U.S. Geological Survey and other Federal and State digital

data, various scales; Universal Transverse Mercator, zone 11;

North American Datum of 1983

Figure 19. Watersheds that contribute recharge to Bicycle Basin, washes, and groundwater-flow model boundary for the Bicycle 

Basin groundwater-flow model, Fort Irwin National Training Center, California.
64 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Model Calibration

The Bicycle Basin model was calibrated through a 

combination of trial-and-error and automated parameterestimation methods. Hydraulic properties, hydraulic 

characteristic of faults, recharge rates, and drain properties 

were modified as part of this process. These parameters were 

estimated by automated parameter-estimation methods using 

a nonlinear-regression, parameter-estimation software known 

as PEST (Doherty, 2010a, b, c), which employs a widely 

used algorithm known as the Gauss-Marquardt-Levenberg 

method. This method adjusts initial parameter values so that 

the weighted sum of the squared differences between the 

observations and their corresponding model-simulated values 

(that is, the objective function) is minimized. Each model cell 

must have values for each physical property (for example, 

hydraulic conductivity or storativity). For most groundwater 

models, this can result in a large number of parameters, 

which can be reduced using parameterization techniques, 

such as the parameter zonation discussed in the “Parameter 

Zonation” section of this report. In the Bicycle Basin model, 

parameterization was used in PEST to characterize the 

following properties:

• Horizontal hydraulic conductivities for layers 1–8 

and vertical anisotropy ratios in layers 1–7 for all 

parameter zones.

• Specific yield (SY) values for model layers 1 and 2 

and specific storage values for model layers 1–8 for 

all parameter zones (SY values for layers 3–6 initially 

were calibrated by trial-and-error and subsequently 

fixed for calibration using PEST; SY values for 

layers 7–8 were specified, but not adjusted during 

model calibration because these layers are confined 

and the values not used).

• Elastic and inelastic skeletal storage properties 

associated with the fine-grained interbeds in layers 2–7 

in parameter zone 6.

• Hydraulic characteristics of horizontal-flow barriers in 

layers 1–8.

• Recharge rates by recharge cell in all recharge zones.

Pest Observation Groups and Parameter Weights

Four observation groups were defined in PEST: 

(1) water levels for initial conditions, (2) transient water 

levels, (3) drawdown, and (4) land-surface deformation. 

Water-level observations for initial conditions, representing 

predevelopment conditions, included the first water-level 

measurements in 21 wells; transient water-level observations 

included 364 measurements in 23 wells (appendix 2) that 

represent conditions during periods of groundwater pumping 

(1967–2010). The 341 drawdown observations were based on 

the transient water levels and were calculated as the waterlevel rise or decline after the first water-level observation. The 

108 observations of land-surface deformation were determined 

at 6 locations (fig. 18) by the methods described in the “LandSurface Deformation” section. In addition, available data 

about what value a parameter should take (prior information) 

can be incorporated into the parameter estimation process 

(Doherty, 2010a). For the Bicycle Basin model, these data 

included hydrologic conductivity and specific yield values at 

selected wells (table 2). 

Because the number of observations at each site varied 

and to prevent sites with many observations from dominating 

the calibration process, sites with fewer observations were 

given additional weight so that the weights for the individual 

sites were spatially consistent. The highest weights were 

given to the land-surface deformation observations, and the 

lowest weights given to the drawdown and initial-conditions 

observations. Observation weights varied within the transient 

water-level and land-surface deformation observation groups. 

The drawdown and initial-condition observations were given 

a weight of one. Most water-level observations were given a 

weight of two; however, higher weights (three or four) were 

given to observations with shorter periods of record. Data 

were not available to determine when subsidence began, 

so the land-surface deformation observations values were 

assumed to begin at zero. These values were included in the 

observation data, but given a weight of zero. The other landsurface deformation observations were given a weight 500, 

with the exception of the observations for well site 14N/3E23B1–3. Greater weight (2,500) was given to observations for 

this site because detailed lithology and borehole geophysical 

data were available to determine the thickness of interbeds 

(appendix fig. 1–3). These land-surface deformation weights 

were considerably larger than the water-level weights because 

there were fewer observations. Weights associated with the 

prior information (table 2) were 300 for hydraulic conductivity 

values from aquifer tests in this study, 10 for reported 

hydraulic conductivity values, and 1 for reported specific yield 

values.
Groundwater-Flow Model 65

Hydrograph and Observed Land-Surface 

Deformation and Simulated Subsidence 

Comparison

Simulated hydraulic heads were compared directly with 

measured groundwater levels if the wells were perforated in 

a single model layer. For wells perforated in multiple model 

layers, MODFLOW-NWT calculated a composite, simulatedequivalent hydraulic head, which is a function of the simulated 

hydraulic heads and hydraulic properties of the perforated 

model layers, by using the hydraulic-head observation 

(HOB) package (Hill and others, 2000). The model layers 

representing the perforated intervals for each observation well 

are given in table 1. Measured water-level data for these wells 

are given in appendix 2. Measures of model fit included the 

following:

• Model-fit statistics for residuals (measured value minus 

simulated value), including the average, median, 

minimum, maximum, and root-mean-square error 

(RMSE). 

• Plotting measured groundwater levels against 

simulated hydraulic heads and residuals against 

simulated hydraulic heads.

• Hydrograph comparison of measured water levels and 

simulated hydraulic heads for the transient simulation 

period (1967–2010).

• Graphical comparison of observed land-surface 

deformation and simulated subsidence for 

September 1995–August 2010 (observed period of 

record).

When plotting simulated hydraulic heads or subsidence 

against measured groundwater levels or observed land-surface 

deformation, all the points would lie on the one-to-one (1:1) 

correlation line if the model results matched the measured 

data perfectly. Similarly, when plotting the residuals against 

the simulated hydraulic heads, all the points would be at zero 

residual if the model results matched the data perfectly.

The RMSE for the transient simulation was 11 ft 

(table 11), indicating an overall good fit of the simulated heads 

to the measured water levels; the RMSE was small relative 

to the approximate 100-ft range of observed and simulated 

head values in the study area (fig. 20). The RMSE for the 

production and unused wells, typically composite water 

levels integrating multiple model layers, was 13 ft; the RMSE 

for the monitoring wells, typically water levels specific to a 

single layer, was 8.5 ft (table 11). The RMSE was the greatest 

for well 14N/3E-14P2 in parameter zone 6 (18 ft) and least 

for production well 14N/3E-13K1 in parameter zone 1 and 

observation well 14N/3E-24Q2 in parameter zone 5 (3.5 ft). 

The RMSE for the land-surface deformation was small 

(0.071 ft; table 12), indicating a good fit between observed and 

simulated subsidence, considering the magnitude of observed 

subsidence was as much as 1.2 ft.

The composite equivalent simulated heads are plotted 

against the measured water levels in figure 20. Simulated 

heads plotting above the 1:1 correlation line indicated the 

model overestimated the measured water levels; conversely, 

simulated heads plotting below the line indicated the model 

underestimated the measured water levels. Overall, the 

measured water levels and simulated heads generally followed 

a 1:1 correlation line; however, there was a bias for the model 

to overestimate measured water levels, which is reflected 

by the greater number of simulated heads plotting above the 

1:1 correlation line (figs. 20A–C).

The residuals are plotted against the simulated hydraulic 

heads in figure 20D. If residuals are randomly distributed 

about zero, there is no bias in the simulated values. In general, 

the plot showed the residuals distributed about zero; however, 

there were a larger number of residuals less than zero 

(59 percent) than greater than zero (41 percent), indicating a 

tendency of the model to overestimate measured water levels.

The observed land-surface deformation is plotted against 

the simulated subsidence in figure 21A. Overall, the values 

generally followed the 1:1 correlation line, indicating a good 

fit. The greater number of simulated values above the line, 

however, indicated the simulated subsidence had a tendency 

to overestimate observed values (fig. 21A). The difference 

between observed and simulated subsidence indicated that 

the model underestimated 29 percent of the observed values, 

whereas 71 percent were overestimated. Uncertainty in the 

thickness of the clay interbeds used in the model might have 

contributed to the general overestimation of subsidence. This 

pattern was evident in the time-series plots of simulated and 

observed subsidence at observation points (fig. 21B). The 

graphs for all observation points, except point 1 (fig. 9A), 

indicated subsidence was overestimated for most of the 

simulation. The graph for point 1 indicated subsidence was 

underestimated for most of the simulation. Temporal patterns 

of simulated heads and subsidence relative to observations are 

discussed in the following section.

Simulated Hydrographs and Subsidence Time 

Series

Simulated heads and measured water levels for wells 

are shown by parameter zone in figures 22A–M. The wells 

represent temporal variations (water-level trends, seasonal 

fluctuations, and vertical gradients) as well as spatial coverage. 

Although the simulated heads approximately matched the 

measured water levels, there were times when the simulated 

heads overestimated or underestimated the measured data. 
66 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Table 11. Summary of model-fit statistics for differences between measured water levels and simulated heads for the Bicycle Basin 

groundwater-flow model, Fort Irwin National Training Center, California.

Well name

Range of residuals

(feet)

Root mean square 

error (RMSE)

(feet)

Number 

of 

Average Median Minimum Maximum measurements

14N/3E-13K1S –0.72 –0.52 –8.1 5.2 3.5 20

14N/3E-13M1S –0.53 –0.65 –14 7.4 6.0 15

14N/3E-13M2S –8.5 –8.3 –25 4.1 12.0 23

14N/3E-13M3S 2.1 1.1 –12 14 6.2 23

14N/3E-13M4 0.66 1.0 –12 5.9 4.3 24

14N/3E-14H1 –8.9 –9.0 –18 4.6 11 21

14N/3E-14P1S 7.6 7.8 –4.4 22 11 9

14N/3E-14P2S –12 –12 –34 13 18 27

14N/3E-22P1S 20 20 20 21 12 7

14N/3E-23B1S –5.2 –6.4 –8.9 –1.6 5.7 13

14N/3E-23B2S –15 –15 –23 –12 16 11

14N/3E-23B3S –12 –12 –13 –11 12 11

14N/3E-23G1S 8.8 11 –25 18 12 30

14N/3E-24H1S –16 –17 –18 –11 17 12

14N/3E-24Q1S 1.6 3.5 –5.2 5.3 3.9 17

14N/3E-24Q2S 0.83 2.40 –5.0 4.5 3.5 17

14N/3E-24Q3S –2.5 –0.12 –14 2.2 5.7 17

14N/3E-24Q4S –7.3 –5.8 –15 –2.3 8.4 17

14N/3E-24Q5S –9.8 –6.9 –20 –5.6 11 17

14N/4E-18N1S 6.6 6.8 –3.8 17 9.9 4

14N/4E-18N2S –8.2 –9.2 –23 17 11 27

Production and 

unused wells

–2.6 –1.6 –34 22 13 172

Monitoring wells –4.1 –3.3 –25 14 8.5 190

All data –3.4 –2.5 –34 22 11 362

1

Water levels for wells 14N/3E-26K1,3–4 were omitted from this table because there was only one measurement each for the deep and shallow wells.

Table 12. Summary of model-fit statistics for differences between observed land-surface deformation and simulated subsidence for 

the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California.

Well name

Range of residuals

(feet)

Root mean square 

error (RMSE)

(feet)

Number of 

measurements

Average Median Minimum Maximum

14N/3E-14P1S –0.066 –0.083 –0.186 0.072 0.106 18

14N/3E-23G1S –0.019 –0.022 –0.052 0.008 0.026 18

14N/3E-23B1–3S –0.013 –0.010 –0.128 0.098 0.072 18

Point 1 0.032 0.030 –0.012 0.095 0.044 18

Point 2 –0.038 –0.043 –0.064 0.007 0.043 18

Point 3 –0.084 –0.101 –0.138 –0.013 0.097 18

All data 0.354 –0.026 –0.186 0.098 0.071 108
Groundwater-Flow Model 67

sac11-0424_fig 20ab

1 to 1 line

2,100

2,120

2,140

2,160

2,180

2,200

2,220

2,240

2,260

Simulated head, in feet

2,100 2,120 2,140 2,160 2,180 2,200 2,220 2,240 2,260

Measured water level, in feet

B

2,080

2,080

EXPLANATION

14N/3E-13K1S

14N/3E-14H1S

14N/3E-22P1S

14N/3E-13M1S

14N/4E18N1S

14N/3E-24H1S

14N/3E-23G1S

14N/3E-14P2S

14N/3E-14P1S

1 to 1 line

2,080

2,100

2,120

2,140

2,160

2,180

2,200

2,220

2,240

2,260

2,080 2,100 2,120 2,140 2,160 2,180 2,200 2,220 2,240 2,260

Simulated head, in feet

Measured water level, in feet

A

Figure 20. Simulated heads from the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California, compared 

with A, measured groundwater levels for all wells; B, measured water levels at production wells; C, measured water levels at monitoring 

wells; and D, differences between measured water levels and simulated heads (residuals).
68 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 20. —Continued

sac11-0424_fig 20cd

30

2,080 2,100 2,120 2,140 2,160 2,180 2,200 2,220 2,240

-30

-20

-10

0

10

20

Residual, in feet

D

Simulated head, in feet

EXPLANATION

Monitoring wells Production and unused wells

2,080

2,100

2,120

2,140

2,160

2,180

2,200

Simulated head, in feet

2,080 2,100 2,120 2,140 2,160 2,180 2,200

Measured water level, in feet

C

1 to 1 line

14N/3E-13M2S

14N/3E-13M3S

14N/3E-13M4S

14N/3E-24Q1S

14N/3E-24Q2S

14N/3E-24Q3S

14N/3E-24Q4S

14N/3E-24Q5S

14N/3E-23B1S

14N/3E-23B2S

14N/3E-23B3S

14N/3E-26K1S

14N/3E-26K3S

EXPLANATION
Groundwater-Flow Model 69

Figure 21. Simulated subsidence from the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California, 

compared with A, observed total land-surface deformation and B, time series of observed land-surface deformation.

sac11-0424_fig 21ab

B

0.0

1.2

1.0

0.8

0.6

0.4

0.2

Observed land-surface deformation and

simulated subsidence, in feet

B

Year

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012

EXPLANATION

Observed land-surface deformation

Simulated subsidence

14N/3E-14P1S

14N/3E-23B1, -23B2S, 

 -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

14N/3E-14P1S

14N/3E-23B1S, -23B2S, 

 -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Simulated subsidence, in feet

0 0.2 0.4 0.6 0.8 1.0 1.2

Observed land-surface deformation, in feet

A

1 to 1 line

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S, 

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3
70 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Mismatches between simulated heads and measured water 

levels can be attributed partly to uncertainty in the estimated 

distribution of annual basin-wide pumpage among active 

wells for 1967–83 and the estimated distribution of monthly 

pumpage from annual values for 1984–90. Estimates of the 

spatial and temporal distribution of pumpage from limited 

data could result in excess or insufficient pumpage in some 

locations, causing overestimation or underestimation, 

respectively, of measured water levels. The variability in 

hydraulic properties in parameter zones, which is not reflected 

in the model, also could contribute to the underestimation or 

overestimation of the measured water levels.

The simulated heads in all wells from the predevelopment 

period through 2010 generally matched the trend and seasonal 

fluctuations of the measured water levels. These results 

indicated the model reasonably simulated the timing and 

magnitude of water-level changes in Bicycle Basin. The 

greatest difference between simulated heads and measured 

water levels was in well 14N/3E-14H1 in parameter 

zone 2 (fig. 22C) and wells 14N/3E-24H1 (fig. 22H) and 

14N/3E-24Q1–5 (fig. 22G) in parameter zone 5. Although 

the measured water levels in well 14N/3E-14H1 generally 

were within the range of fluctuation of the simulated heads, 

the overall trend in the simulated heads showed smaller 

declines than the measured water levels for January 1993–

July 2000. For well 14N/3E-24H1, simulated heads were 

consistently about 15 ft higher than measured water levels. 

Simulated heads were higher than measured water levels in 

wells 14N/3E-24Q3–5 and 14N/3E-24Q1 for July 1997–

January 2002. These discrepancies can be attributed to 

uncertainties in the earlier estimates of the spatial distribution 

of pumping. Simulated heads were in good agreement with 

measured water levels in wells 14N/3E-24Q1 and 14N/3E24Q2 for March 2005–December 2010. However, the vertical 

gradient between these wells was not well simulated because 

both wells are screened only in model layer 8 (table 1). 

The differences between simulated heads and measured 

groundwater levels among model layers indicated that vertical 

hydraulic gradients fluctuated and even reversed in some 

parts of the basin as pumpage rates changed seasonally and 

annually. This reversal of gradients was evident in parameter 

zone 2, where the direction of vertical flow in wells 14N/3E13M2–4 varied in the simulated as well as the measured 

values (table 13). Although the model simulated the hydraulic 

gradient variability with seasonal pumping reasonably in this 

zone, the magnitude of the fluctuations differed considerably 

between the simulated and measured values. In parameter 

zone 5, the measured vertical water-level differences between 

wells 14N/3E-24Q5 and 14N/3E-24Q4 indicated a downward 

direction of flow, which also was simulated by the model. 

The measured vertical water-level differences between wells 

14N/3E-24Q4 and 14N/3E-24Q3 and wells 14N/3E-24Q3 

and 14N/3E-24Q2, however, indicated an upward direction of 

flow, whereas the model simulated a downward direction for 

wells 14N/3E-24Q4 and 14N/3E-24Q3 and variable direction 

of flow for wells 14N/3E-24Q3 and 14N/3E-24Q2 (table 13). 

The simulated magnitudes of vertical head difference also 

differed considerably from the measured values (table 13). 

The discrepancies between measured vertical water-level 

differences and simulated hydraulic head differences in 

parameter zones 2 and 5 can primarily be attributed to the 

uncertainty in the distribution of stresses in the basin. In 

parameter zone 6, the hydraulic gradient between wells 

14N/3E-23B3 and 14N/3E-23B2 was simulated by the model. 

The simulated vertical head differences and direction of 

flow in parameter zone 6, given for wells 14N/3E-23B1–3 in 

table 13, mostly agreed with the measured values owing to 

the explicit simulation of the confining Quaternary-Tertiary 

lacustrine (QTol) geologic unit by model layers 3–5 in this 

parameter zone. Model layers 3–5 restricted vertical flow 

from the shallower layers to model layer 6, where most of the 

pumping was centered, which allowed the model to simulate 

the direction of vertical flow and magnitude of the vertical 

head differences created by the pumping reasonably well.

Simulated subsidence and observed land-surface 

deformation at wells 14N/3E-14P1 14N/3E-23B1–3, and 

14N/3E-23G1 and at points 1–3 in parameter zone 6 (fig. 18) 

during September 1995–August 2010 are shown in figure 21B. 

Data were not available to determine when subsidence 

began, so the observed and simulated values begin at zero. It 

is likely, however, that subsidence began before November 

1993 because the decline in water levels began before then. 

In general, the simulated subsidence corresponded with the 

observed subsidence. The maximum simulated subsidence 

ranged from 0.30 ft at well 14N/3E-23G1 to 1.03 ft at well site 

14N/3E-23B1–3. At well 14N/3E-23G1, the model simulated 

the observed data reasonably well. At well site 14N/3E23B1–3, simulated subsidence was greater than the observed 

data through 2001 and less than the observed data after 2006 

(fig. 21B). Between these dates, however, the model simulated 

measured subsidence reasonably well. At well 14N/3E-14P1, 

the model overestimated subsidence through October 2006, 

but simulated observed subsidence reasonably well after 

that date. Simulated subsidence was greater than observed 

subsidence at points 2 and 3 and less for point 1 for the period 

of record (fig. 21B). 

Mismatches between the observed and simulated 

values primarily can be attributed to uncertainty in the 

thickness and lateral heterogeneity of the fine-grained 

interbeds in model layers 2–7, because detailed lithologic 

and borehole geophysical data for parameter zone 6 are 

limited. Uncertainties associated with the interpretation of the 

interferograms described in the “Land-Surface Deformation” 

section of this report also can contribute to mismatches 

between measured and simulated subsidence.
Groundwater-Flow Model 71

sac11-0424_fig 22abc

2,100

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,120

2,140

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

2,100

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,120

2,140

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

Year

Water-level elevation, in feet

2,260

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

2,100

2,125

2,150

2,175

2,200

2,225

2,250

14N/4E-18N1S

14N/4E-18N2S

EXPLANATION

EXPLANATION

Measured water level

Simulated hydraulic

 head model layer

1

2

3

4

5

6

7

Simulated hydraulic

 head model layer

3

4

5

6

7

8

Measured water level

EXPLANATION

Measured water level

Simulated hydraulic head model layer

4

5

6

7

2

3

A. 14N/4E-18N1, 2

B. 14N/3E-13K1

C. 14N/3E-14H1

Figure 22. Measured groundwater levels and simulated heads in wells in the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California: A, 14N/4E-18N1,2; B, 14N/3E-13K1; C, 14N/3E-14H1; D, 14N/3E-13M1; E, 14N/3E-13M2–4; F, 14N/3E26K1, 3–4; G, 14N/3E-24Q1–5; H, 14N/3E-24H1; I, 14N/3E-23G1; J; 14N/3E-23B1–3; K, 14N/3E-14P1; L, 14N/3E-14P2; M, 14N/3E-22P1.
72 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 22. —Continued

sac11-0424_fig 22def 1962 1964 1966

1968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,100

2,125

2,150

2,175

2,200

2,225

2,250

Water-level elevation, in feet

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,050

2,100

2,150

2,200

Water-level elevation, in feet

2,100

1992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016

Year

2,140

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

2,250

2,120

2,075

D. 14N/3E-13M1

E. 14N/3E-13M2–4

F. 14N/3E-26K1, 3–4;

EXPLANATION

Simulated hydraulic

head model layer

3

5

7

14N/3E-13M4S

14N/3E-13M3S

14N/3E-13M2S

EXPLANATION

2

3

14N/3E-26K3S

14N/3E-26K4S

14N/3E-26K1S

Measured water

level

Simulated hydraulic

head model layer

Measured water

level

EXPLANATION

Measured water level

Simulated hydraulic head model layer

4

5

6

7

2

3
Groundwater-Flow Model 73

Figure 22. —Continued

sac11-0424_fig 22ghi 1962 1964 1966

1968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,160

2,180

2,200

2,220

Water-level elevation, in feet

2,240

2,120

2,140

2,140

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,120

2,140

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

EXPLANATION

Measured water

level

Simulated hydraulic

 head model layer

3

4

6

7

8

14N/3E-24Q5S

14N/3E-24Q4S

14N/3E-24Q3S

14N/3E-24Q2S

14N/3E-24Q1S

EXPLANATION

Measured water level

Simulated hydraulic

 head model layer

1

2

3

4

EXPLANATION

Measured water level

Simulated hydraulic

 head model layer

1

2

3

4

5

6

7

8

G. 14N/3E-24Q1–5

H. 14N/3E-24H1

I. 14N/3E-23G1
74 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 22. —Continued

sac11-0424_fig 22jkl 1962 1964 1966

1968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,120

2,180

2,200

2,220

2,240

Water-level elevation, in feet

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

Water-level elevation, in feet

2,080

2,100

2,080

1962196419661968197019721974197619781980198219841986198819901992199419961998200020022004200620082010201220142016

Year

2,120

2,140

2,160

2,180

2,200

2,220

2,240

Water-level elevation, in feet

2,100

2,160

2,140

2,120

2,180

2,200

2,220

2,240

2,100

2,160

2,140

EXPLANATION

Simulated hydraulic Measured water level

 head model layer

2

6

7

14N/3E-23B3S

14N/3E-23B2S

14N/3E-23B1S

EXPLANATION

Measured water level

Simulated hydraulic

 head model layer

5

6

EXPLANATION

Measured water level

Simulated hydraulic

 head model layer

5

6

J. 14N/3E-23B1–3

K. 14N/3E-14P1

L. 14N/3E-14P2
Groundwater-Flow Model 75

sac11-0424_fig 22m 1992 1993

19941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016

Year

2,180

2,230

2,240

2,250

2,260

Water-level elevation, in feet

2,160

2,170

2,200

2,190

2,220

2,210 Measured water level

EXPLANATION

Simulated hydraulic

 head model layer

1

2

3

M. 14N/3E-22P1

Figure 22. —Continued
Table 13. Summary of average, minimum, and maximum vertical differences in measured water levels and simulated heads, and direction of flow fosites for 1997–2010 in the Bicycle Basin, Fort Irwin National Training Center, California. [Wells 14N/3E-13M2–4 is in parameter zone 2; 14N/3E-24Q1–5 is in parameter zone 5; and 14N/3E-23B1–3 is in parameter zone 6. See figure 15A for location of parameter zo

Abbreviation: ID, identification] State well number Local ID Model layer intersected by perforated interval of well Number of data values Measured Simu

Average vertical water-level difference (feet)1,2 Vertical water-level difference (feet) Direction of flow Average vertical head difference (feet)3 Ve

head d

(f

Minimum Maximum Minimum 

14N/3E-13M4S BLA2-3 3 22 0.07 –1.6 1.2 Variable 1.6 –0.9 

14N/3E-13M3S BLA2-2 5 22 0.07 –1.6 1.2 Variable 1.6 –0.9 

14N/3E-13M3S BLA2-2 5 23 8.1 –0.4 22 Variable –1.5 –32 

14N/3E-13M2S BLA2-1 7 23 8.1 –0.4 22 Variable –1.5 –32 

14N/3E-24Q5S BLA3-5 3–4 17 0.65 0.3 0.90 Downward 3.1 0.62 

14N/3E-24Q4S BLA3-4 6 17 0.65 0.3 0.90 Downward 3.1 0.62 

14N/3E-24Q4S BLA3-4 6 17 –1.0 –1.2 –0.60 Upward 3.9 0.25 

14N/3E-24Q3S BLA3-3 7 17 –1.0 –1.2 –0.60 Upward 3.9 0.25 

14N/3E-24Q3S BLA3-3 7 17 –1.4 –1.9 –0.40 Upward 1.8 –2.8 

14N/3E-24Q2S BLA3-2 8 17 –1.4 –1.9 –0.40 Upward 1.8 –2.8 

14N/3E-24Q2S BLA3-2 8 17 –0.8 –1.7 0.55 Variable 0.0 0.0 

14N/3E-24Q1S BLA3-1 8 17 –0.8 –1.7 0.55 Variable 0.0 0.0 

14N/3E-23B3S BLA4-3 2–3 11 26 9.0 37 Downward 23 7.1 

14N/3E-23B2S BLA4-2 6 11 26 9.0 37 Downward 23 7.1 

14N/3E-23B2S BLA4-2 6 11 –25 –32 –10 Upward –16 –29 

14N/3E-23B1S BLA4-1 7 11 –25 –32 –10 Upward –16 –29 

1The measured vertical water-level differences were calculated from the data given in appendix 2.2The average vertical water-level or head difference is the sum of shallow minus deep divided by the number of data values; a positive value indicates that the shallower value 

the converse is true for a negative number.

3Simulated heads are calculated at the center of the model cell, which does not necessarily coincide with altitudes of the perforated intervals of the wells.
Groundwater-Flow Model 77

Model Sensitivity

A sensitivity analysis was performed on the model 

parameters and stresses to test how robust the parameter 

values estimated during the calibration process were. The 

analysis involved keeping all input parameters and tested 

model stresses constant, except the one being analyzed, 

and varying that parameter or model stress through a range 

of values that included the uncertainties in that parameter 

or stress. Varying a parameter or stress by a small amount 

causes a large change in the simulation results for a sensitive 

parameter (more robust); an insensitive parameter causes a 

small change in the simulation results (less robust). Model 

sensitivity was evaluated using PEST (Doherty, 2010a). 

Calculations presented in this section assume the 

Bicycle Basin model results varied linearly with changes in 

parameter value; however, the model sensitivity could be 

greater because of a non-linear response of the model. For 

the analysis in this section, all prior information was removed 

from the objective function. Values for the 144 parameters 

that were log transformed during calibration with PEST 

were not transformed for the sensitivity analysis. To 

determine composite sensitivity values for all observation 

types, 160 parameters were tested with 834 observations. 

Multiplying the composite sensitivity by the parameter value 

provided the relative composite sensitivity (table 14; fig. 23), 

which allows for comparison of the composite sensitivities 

of parameters of different magnitudes (Doherty, 2010a). 

When comparing the sensitivities of different parameter 

groups, however, consideration should be given to how 

the adjustment affects the parameter value. For example, 

adjustment to a sensitive parameter of a specific group can 

result in an unrealistic value, whereas a similar adjustment to 

an insensitive parameter of a different group can result in a 

value that still could be reasonable (Doherty, 2010a; Traum 

and others, 2014).

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Horizontal hydraulic conductivity (ft/day)

hkl1z1 1 1 29 1.07E-01 33

hkl2z1 2 1 20 5.42E-02 48

hkl3z1 3 1 20 2.15E-01 25

hkl4z1 4 1 10 7.90E-02 39

hkl5z1 5 1 8.3 8.02E-02 38

hkl6z1 3 1 0.81 1.15E-01 31

hkl7z1 7 1 0.63 7.42E-02 40

hkl8z1 8 1 0.34 2.30E-01 22

hkl1z2 1 2 1.6 2.42E-01 21

hkl2z2 2 2 2.0 6.07E-02 45

hkl3z2 3 2 6.5 9.14E-02 35

hkl4z2 4 2 4.0 2.12E-02 78

hkl5z2 5 2 14 2.26E-01 23

hkl6z2 3 2 1.7 2.35E-02 75

hkl7z2 7 2 2.8 5.70E-02 46

hkl8z2 8 2 0.78 9.23E-03 92

hkl1z3 1 3 23 5.65E-03 100

hkl2z3 2 3 1.3 7.15E-02 41

hkl3z3 3 3 1.6 3.34E-02 62

hkl4z3 4 3 19 3.55E-03 114

hkl5z3 5 3 3.5 1.15E-02 86
78 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Horizontal hydraulic conductivity (ft/day)—Continued

hkl6z3 3 3 15 9.99E-03 91

hkl7z3 7 3 5.4 6.48E-02 43

hkl8z3 8 3 5.2 3.85E-03 110

hkl1z4 1 4 7.1 4.36E-01 11

hkl2z4 2 4 30 1.09E-02 87

hkl3z4 3 4 7.0 3.63E-03 113

hkl1z5 1 5 32 1.05E-01 34

hkl2z5 2 5 10 2.50E-02 72

hkl3z5 3 5 9.2 2.05E-02 79

hkl4z5 4 5 1.0 2.72E-01 20

hkl5z5 5 5 3.9 3.97E-02 56

hkl6z5 6 5 8.8 3.11E-01 16

hkl7z5 7 5 0.14 1.03E-02 89

hkl8z5 8 5 0.13 3.49E-02 60

hkl1z6 1 6 3.5 4.16E-01 12

hkl2z6 2 6 18 5.33E-02 49

hkl3z6 3 6 0.92 4.18E-02 54

hkl4z6 4 6 0.06 3.08E-01 17

hkl5z6 5 6 0.04 3.94E-01 14

hkl6z6 6 6 33 5.20E-01 10

hkl7z6 7 6 0.13 2.95E-01 18

hkl8z6 8 6 0.10 3.06E-02 65

hkl1z7 1 7 0.23 3.53E-02 58

hkl2z7 2 7 0.15 1.95E-02 81

hkl3z7 3 7 0.15 7.30E-03 97

Vertical anisotropy ratio (dimensionless)

vanl1z1 1 1 2,875 8.50E-02 37

vanl2z1 2 1 1,123 2.79E-02 67

vanl3z1 3 1 997 6.36E-02 44

vanl4z1 4 1 27 1.72E-03 136

vanl5z1 5 1 14 1.28E-03 143

vanl6z1 6 1 57 4.23E-02 53

vanl7z1 7 1 1,325 1.74E-02 82

vanl1z2 1 2 1,263 2.26E-01 24

vanl2z2 2 2 122 4.51E-02 50

vanl3z2 3 2 83 1.21E-02 85

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.—Continued

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]
Groundwater-Flow Model 79

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Vertical anisotropy ratio (dimensionless)—Continued

vanl4z2 4 2 2.0 3.66E-03 111

vanl5z2 5 2 548 2.45E-02 74

vanl6z2 6 2 5914 2.47E-02 73

vanl7z2 7 2 3,772 4.17E-03 106

vanl1z3 1 3 6.3 1.73E-03 135

vanl2z3 2 3 39 3.51E-02 59

vanl3z3 3 3 68 3.30E-02 63

vanl4z3 4 3 2.6 1.82E-03 133

vanl5z3 5 3 26 8.41E-03 94

vanl6z3 6 3 11 3.26E-03 119

vanl7z3 7 3 5,770 6.72E-02 42

vanl1z4 1 4 5,255 1.13E-01 32

vanl2z4 2 4 94 3.65E-03 112

vanl3z4 3 4 22 1.69E-03 137

vanl1z5 1 5 64 2.56E-02 71

vanl2z5 2 5 3.9 2.46E-03 129

vanl3z5 3 5 33 7.98E-03 96

vanl4z5 4 5 56 2.77E-01 19

vanl5z5 5 5 2.0 2.52E-03 127

vanl6z5 6 5 57 2.58E-02 70

vanl7z5 7 5 16,592 6.02E-03 98

vanl1z6 1 6 22,255 8.80E-02 36

vanl2z6 2 6 18 3.28E-03 118

vanl3z6 3 6 1,123 1.00E-02 90

vanl4z6 4 6 1,499 1.51E-01 28

vanl5z6 5 6 13,806 1.69E-01 27

vanl6z6 6 6 10,169 3.29E-03 117

vanl7z6 7 6 2,944 1.23E-01 30

vanl1z7 1 7 3,318 4.63E-03 103

vanl2z7 2 7 1,391 2.84E-03 123

vanl3z7 3 7 1,411 2.19E-03 131

Specific yield (dimensionless)

syl1z1 1 1 0.12 1.35 4

syl1z2 1 2 0.19 2.09E-01 26

syl2z2 2 2 0.19 1.07 5

syl1z3 1 3 0.23 1.39E-01 29

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.—Continued

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]
80 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Specific yield (dimensionless)—Continued

syl1z4 1 4 0.12 3.75E-01 15

syl1z5 1 5 0.13 1.85 1

syl1z6 1 6 0.10 8.80E-01 7

syl1z7 1 7 1.93E-02 2.68E-02 69

Specific storage (1/ft)

ssl2z1 2 1 8.99E-07 2.76E-03 124

ssl3z1 3 1 3.21E-05 4.11E-02 55

ssl4z1 4 1 3.56E-06 8.06E-03 95

ssl5z1 5 1 4.23E-05 4.31E-02 52

ssl6z1 3 1 1.28E-05 2.22E-02 76

ssl7z1 7 1 1.33E-05 3.93E-02 57

ssl2z2 2 2 8.65E-07 1.29E-03 142

ssl3z2 3 2 3.86E-06 2.50E-03 128

ssl4z2 4 2 4.06E-06 1.52E-03 138

ssl5z2 5 2 4.95E-05 3.48E-02 61

ssl6z2 3 2 7.72E-06 2.94E-02 66

ssl7z2 7 2 8.55E-07 4.45E-02 51

ssl2z3 2 3 2.53E-06 3.88E-03 109

ssl3z3 3 3 8.07E-07 1.43E-03 141

ssl4z3 4 3 8.99E-07 3.43E-03 116

ssl5z3 5 3 1.59E-06 1.81E-03 134

ssl6z3 3 3 1.27E-06 1.20E-03 144

ssl7z3 7 3 8.43E-07 4.04E-03 108

ssl2z4 2 4 8.71E-07 3.48E-03 115

ssl3z4 3 4 2.07E-06 2.66E-03 125

ssl2z5 2 5 1.97E-06 4.83E-03 102

ssl3z5 3 5 8.58E-07 1.50E-03 139

ssl4z5 4 5 8.95E-07 2.60E-03 126

ssl5z5 5 5 8.66E-07 1.90E-03 132

ssl6z5 3 5 1.71E-06 5.77E-03 99

ssl7z5 7 5 8.28E-07 9.03E-03 93

ssl2z6 2 6 9.78E-06 2.74E-02 68

ssl6z6 6 6 9.65E-07 1.08E-02 88

ssl7z6 7 6 8.99E-07 5.48E-02 47

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.—Continued

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]
Groundwater-Flow Model 81

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Specific storage (1/ft)—Continued

ssl2z7 2 7 3.87E-06 4.06E-03 107

ssl3z7 3 7 1.34E-06 3.03E-03 121

Delayed inelastic skeletal specific storage (1/ft) 

sskv2 2 6 1.58E-04 1.84 2

sskv6 6 6 8.55E-05 1.66 3

sskv7 7 6 8.46E-05 6.99E-01 9

Instantaneous inelastic skeletal specific storage (1/ft)

skv3 3 6 5.38E-05 8.42E-01 8

skv4 4 6 6.71E-05 9.70E-01 6

skv5 5 6 5.44E-05 4.12E-01 13

Delayed elastic skeletal specific storage (1/ft)

sske2 2 6 1.08E-05 2.37E-03 130

sske6 6 6 8.00E-06 2.15E-02 77

sske7 7 6 8.46E-06 3.15E-03 120

Instantaneous inelastic skeletal specific storage (1/ft)

ske3 3 6 7.58E-06 4.30E-03 105

ske4 4 6 4.14E-06 6.22E-04 147

ske5 5 6 3.27E-06 1.44E-03 140

Recharge (ft/day)

rech1 1 — 9.25E-04 6.57E-05 149

rech2 1 — 2.99E-03 9.84E-04 145

rech3 1 — 1.81E-05 1.89E-08 154

rech4 1 — 4.62E-06 2.69E-09 156

rech5 1 — 2.70E-05 6.97E-08 152

rech6 1 — 4.11E-06 2.38E-09 157

rech7 1 — 3.09E-06 4.75E-09 155

rech8 1 — 9.10E-06 1.43E-09 159

rech9 1 — 4.85E-05 6.63E-08 153

rech10 1 — 9.31E-05 1.79E-07 150

rech11 1 — 3.42E-06 1.23E-09 160

rech12 1 — 3.42E-05 8.53E-08 151

rech13 1 — 3.76E-06 2.18E-09 158

Drain conductance (ft2

/day)

drncond 1 — 4,335 3.10E-02 64

Hydraulic characteristic (1/d)

coyotecl1 1 — 9.50E-03 2.92E-03 122

coyotecl28 2–8 — 2.58E-07 1.40E-02 83

unnamedl1 1 — 1.15 5.35E-03 101

unnamedl2 2 — 9.75E-03 2.02E-02 80

unnamedl3 3 — 5.02E-03 4.36E-03 105

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.—Continued

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]
82 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 23 shows the relative composite sensitivities 

by parameter group for the most sensitive 50 of the 

160 parameters included in the sensitivity analysis, in order 

of highest to lowest sensitivity. The parameters in table 14

were grouped by hydraulic conductivity, vertical anisotropy, 

storage properties (specific yield, specific storage, and elastic 

and inelastic skeletal storage properties), recharge, drain 

conductance, and hydraulic characteristic of horizontal flow 

barriers (faults). The parameter names and descriptions also 

are given in table 14. The parameters within the groups shown 

in figure 23 include members of five of the groups used in the 

table: specific yield, specific storage, inelastic skeletal storage, 

hydraulic conductivity, and vertical anisotropy. Results of the 

sensitivity analysis indicated the model was most sensitive to 

storage properties, including specific yield (syl1z5, syl1z1, and 

sy2z2) and inelastic skeletal storage properties (skv2, skv6, 

skv4, skv3, and skv7). The next most sensitive parameters 

included hydraulic conductivity, other storage properties, 

and vertical anisotropy ratios (table 14; fig. 23). The model 

was least sensitive to the recharge rates for model cells in the 

recharge zones, the elastic storage coefficient for model layer 

4, and the hydraulic characteristic for the unnamed fault 2 in 

model layers 2 and 3 (ske4, unnamedl2_1 and unnamedl3_1, 

respectively, table 14).

Parameter name Model layer Parameter zone 

number

Final parameter 

value

Relative composite 

sensitivity Rank

Hydraulic characteristic (1/d)—Continued

unnamedl1_1 1 — 0.39 1.22E-02 84

unnamedl2_1 2 — 4.41E-01 2.17E-04 148

unnamedl3_1 3 — 0.87 7.21E-04 146

Table 14. Parameter names, relative composite sensitivity values, and sensitivity rank in the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.—Continued

[Number in recharge parameter name corresponds to recharge zone in figure 15A. Abbreviations: ft, foot; d, day; ft/day, feet per day, ft2/day, square feet per day; 

—, not applicable]

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

syl1z5skv2skv6syl1z1syl2z2skv4syl1z6skv3skv7hkl6z6hkl1z4hkl1z6skv5hkl5z6syl1z4hkl6z5hkl4z6hkl7z6vanl4z5hkl4z5hkl1z2hkl8z1hkl5z2vanl1z2hkl3z1syl1z2vanl5z6vanl4z6syl1z3vanl7z6hkl6z1vanl1z4hkl1z1hkl1z5hkl3z2vanl1z6vanl1z1hkl5z1hkl4z1hkl7z1hkl2z3vanl7z3hkl7z3vanl3z1hkl2z2hkl7z2ssl7z6hkl2z1hkl2z6vanl2z2

Relative composite sensitivity

Parameter

EXPLANATION

Parameter groups

Storage property (sy, skv, ss)

Hydraulic conductivity (hk)

Vertical anisotropy ratio (van)

(See table 14 for explanation of 

parameter names)

Figure 23. Relative composite sensitivities for the 50 most sensitive parameters for the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.
Groundwater-Flow Model 83

Model Results

The Bicycle Basin model was used to simulate 

distributions of drawdown in all model layers (drawdown 

in layers 1 and 6 are shown in fig. 24) at the end of the 

simulation period, the distribution of subsidence (fig. 25), 

and components of the groundwater budget (table 15). Model 

layer 1 was chosen to represent the water table, and model 

layer 6 was chosen to represent the layer with most of the 

pumpage. Simulated drawdown is the difference between 

simulated heads at the end of the steady-state period (before 

1967) and simulated heads at the end of the transient period 

(December 2010). Subsidence is the sum of the compaction 

at the end of the simulation period in each model layer 

containing fine-grained interbeds (layers 2–7) in parameter 

zone 6. The simulated groundwater budget is presented 

for the steady-state, before 1967, and transient simulation 

periods, 1967–2010.

Simulated Drawdown

The distributions of drawdown in all model layers 

generally were similar with the larger amount of drawdown 

north of the South Coyote Canyon fault and smaller amount 

of drawdown south of the fault. Simulated drawdown in 

model layer 1 in the Bicycle Basin ranged from no drawdown 

or increased hydraulic head in the western part of the basin, 

primarily in zone 7, to more than 100 ft in parameter zone 2 

(fig. 24A). The absence of drawdown in the western part of 

the basin (parameter zone 7) was because the recharge rate 

in recharge zone 1 (fig. 15A) was comparatively high and 

there were no production wells in that part of the basin. Total 

groundwater pumpage of about 47,000 acre-ft from 1967 

through 2010 (table 15) resulted in drawdown of as much 

as 189 ft in model layer 6 (fig. 24B). Simulated drawdown 

in this model layer ranged from 65 ft in parameter zone 

5 to more than 110 ft in the area around production wells 

14N/3E-14P1 in parameter zone 6 and in parameter zone 2 

(fig. 24B). This drawdown resulted in water-quality changes in 

nearby well 14N/3E-23B2 that are described in the “General 

Water-Quality Characteristics and Areal Variation” section. 

Groundwater pumpage from production well 14N/4E18N1 resulted in simulated drawdown of more than 100 ft 

in a pumping depression around this well (fig. 24B). The 

drawdowns in model layer 6 were larger than in model layer 

1 because model layer 6 intersects the perforations of the 

five production wells, whereas model layer 1 intersects the 

perforations of only one production well. Pumping in this well 

was discontinued in October 1986, allowing the water table to 

recover to some extent. Drawdown in order of layers 2–5 and 

7–8 ranged from 49 to 181 ft, 51 to 181 ft, 59 to 181 ft, 62 to 

181 ft, 74 to 192 ft, and 74 to 189 ft, respectively.

Simulated Subsidence

The areal distribution of total simulated subsidence 

at the end of the simulation period showed that subsidence 

was greatest in the center of parameter zone 6 and generally 

decreased toward the parameter-zone boundary (fig. 25). 

Simulated subsidence in a wedge-shaped area in the vicinity of 

point 1 and well 14N/3E-23G1 was less than the surrounding 

areas (fig. 25) because the thickness of the fine-grained 

interbeds was reduced or omitted in that area of the model, as 

discussed in the “Elastic and Inelastic Storage” section.

Water Budgets

Groundwater budgets for the steady-state and transient 

stress periods are given in table 15. The monthly variation and 

cumulative volumes of selected budget components are shown 

in figure 26. Between January 1967 and December 2010, 

about 5,100 acre-ft of water was recharged in the Bicycle 

Basin, and about 47,000 acre-ft of groundwater was pumped 

from the basin (table 15; fig. 26A, B, respectively), resulting 

in declining water levels throughout the basin (fig. 22) and 

subsidence in parameter zone 6 (fig. 21B). Simulated outflow 

from the Bicycle Basin, simulated as a drain, decreased from 

1967 to 1999 (table 15; fig. 26C). Total groundwater-storage 

depletion (total inflows minus total outflows) was about 

42,100 acre-ft (table 15), indicating that about 91 percent of 

pumpage was from depletion of groundwater storage, about 

4.7 percent from reduced outflow from the basin, and about 

2.3 percent from net instantaneous and delayed compaction 

of interbeds (total compaction inflow minus total compaction 

outflow). Net pumpage (pumpage minus well loss) was 

used to calculate the percentages. These percentages do 

not sum to 100 percent because of rounding of numbers. A 

trend of declining monthly pumpage between August 2005 

and June 2007 (fig. 26B) reduced the rate of decline in 

groundwater storage during that period (fig. 26F).
84 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 24. Simulated drawdown from the end of the predevelopment period (before 1967) to the end of the simulation period in 

December 2010 for the groundwater-flow model of the Bicycle Basin, Fort Irwin National Training Center, California, for A, model layer 1 

and B, model layer 6.

sac11-0424_fig 24ab

R. 3 E. R. 4 E.

T.

14

N.

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

A

B 116°40’ 116°38’ 116°36’ 35°18’ 35°16’

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Recharge cells—See figure 15A

for recharge-zone numbers.

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 1, in feet

Model fault

Township/range

Base modified from U.S. Geological Survey and other Federal digital

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

−59 to −40

−39 to −20

−19 to 0

1 to 20

21 to 40

41 to 60

Simulated drawdown in model 

 layer 1, in feet

61 to 80

81 to 100

101 to 110

111 to 120

121 to 130

131 to 140

EXPLANATION

65 to 80

81 to 100

101 to 110

111 to 120

121 to 130

Simulated drawdown in model 

layer 6, in feet

Bicycle groundwater basin

Model boundary

Model grid

Recharge cells—See figure 15A

for recharge-zone numbers.

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 1, in feet

Model fault

Township/range

Production

Multiple-well

monitoring site

Well type and identifier (see table 1)

131 to 140

141 to 150

151 to 160

161 to 170

171 to 189

13K1

13M3

Zone 1

Zone 1

Destroyed

Test well

Obstructed

22P1

23G1

Production

Multiple-well

monitoring site

Well type and identifier (see table 1)

13K1

13M3

Destroyed

Test well

Obstructed

22P1

23G1

24H1

24H1

100

0

80

40

0

20

60

100

80

60

80

40

60

40

120

120

100

160

140

100

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

90

100

80

110

100

120110

130

170

150

140

70

100

100

No-flow

boundary

No-flow

boundary

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7
Groundwater-Flow Model 85

Figure 25. Simulated subsidence at the end of the simulation period in December 2010 for the Bicycle Basin groundwater-flow model, 

Fort Irwin National Training Center, California.

sac11-0424_fig 25

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

0 0.5 1 MILE

0 10.5 KILOMETER

EXPLANATION

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

0.00

0.01 to 0.20

0.21 to 0.40

0.41 to 0.60

Subsidence, in feet

0.61 to 0.80

0.81 to 1.00

1.01 to 1.18

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Subsidence contour

Simulated fault

Township/range

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Well type and identifier (see table 1)

13K1

23G1

22P1

26K1

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

PT2 Model calibration-control

 point and identifier

Zone 1

24H1

18N2

18N1

23G1 24H1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

1.0

0.2 0.4

0.8

0.6

No-flow

Zone 1 boundary

Zone 2

Zone 3

Zone 4

Zone 5

Zone 7 Zone 6

PT2

PT3

PT1
Table 15. Simulated predevelopment and transient (1967–2010) groundwater budgets for the Bicycle Basin groundwater-flow model, Fort Irwin NatioCalifornia. [Units are in acre-feet] Year Recharge Well loss Inflows Outflows 

No-delay interbed storage Delay interbed storage Total inflows Drains Pumpage No-delay interbed storage Delay interbed storage 

Steady state 116 0 0 0 116 116 0 0 0 

1967 116 1.1 0.51 1.1 119 116 823 0 0 1968 116 1.2 0.29 0.87 118 114 821 0 0 1969 116 1.5 0.41 1.0 119 111 955 0 0 

1970 116 1.5 0.36 0.83 119 107 897 7.4E–06 0 1971 116 1.2 0.13 0.42 118 104 609 0.02 0.02 1972 116 1.0 0.11 0.30 117 101 481 7.1E–03 6.1E–03 1973 116 2.0 0.01 0.04 118 98 159 0.08 0.15 1974 116 0.5 0.04 0.07 117 96 171 2.2E–04 0.04 1975 116 0.5 0.06 0.12 117 94 210 0 4.2E–03 

1976 116 0.7 0.17 0.37 117 93 394 0 0 1977 116 1.4 0.01 0.05 117 92 124 0.06 0.10 1978 116 0.8 0.41 0.53 118 91 494 0 0 1979 116 0.8 0.49 0.39 118 89 462 1.4E–05 0 1980 116 1.4 2.1 0.94 120 88 867 0 0 

1981 116 1.3 1.7 0.70 120 85 794 8.7E–05 0 

1982 116 1.3 1.9 0.63 120 82 759 0 0 

1983 116 1.5 2.5 0.77 121 79 867 0 0 

1984 116 16 4.4 1.6 138 76 706 0.12 0.20 

1985 116 3.9 6.8 2.7 129 72 1,247 0.06 0.10 

1986 116 23 7.9 3.5 150 66 1,352 0.36 0.69 

1987 116 56 3.6 1.5 177 59 878 0.21 0.52 1988 116 37 5.9 2.3 162 52 1,070 0.21 0.43 1989 116 22 5.3 2.3 146 46 852 0.19 0.32 1990 116 8.4 8.8 5.5 139 41 1,319 0.12 0.13 

1991 116 11 8.9 8.8 145 34 1,391 0.46 0.35 

1992 116 21 8.1 11 156 27 1,158 0.45 0.16 

1993 116 17 5.8 7.7 147 21 774 0.50 0.30 1994 116 20 7.5 12 156 15 979 0.35 0.01 
Year Recharge Well loss

Inflows Outflows 

No-delay 

interbed storage

Delay interbed 

storage

Total 

inflows Drains Pumpage No-delay interbed storage Delay interbed storage 

1995 116 14 9.2 16 155 10 1,061 0.17 0.02 1996 116 25 11 22 175 7.3 1,247 1.0 0.12 

1997 116 36 18 83 252 4.5 1,560 0.25 0.12 

1998 116 57 27 82 281 1.7 2,195 0.62 4.7 

1999 116 54 18 40 227 0 1,867 0.54 5.7 

2000 116 74 23 57 270 0 1,981 0.11 0.4 2001 116 51 20 42 229 0 1,947 0.22 4.8 

2002 116 54 17 37 224 0 2,033 0.35 4.9 

2003 116 25 18 41 201 0 1,967 0.30 6.3 

2004 116 15 21 57 209 0 1,953 0.08 1.8 

2005 116 8.8 20 48 192 0 1,546 0.10 1.7 

2006 116 18 18 43 195 0 1,288 0.14 2.0 

2007 116 30 15 36 197 0 1,390 0.27 5.9 

2008 116 24 11 31 182 0 893 0.45 7.1 

2009 116 28 12 33 189 0 1,208 0.30 6.4 

2010 116 22 9.8 26 174 0 1,112 0.12 2.0 

1967–2010 Total 5,104 791 353 761 7,008 2,172 146,857 8.2 58 

1Net pumpage (pumpage minus well loss) differs from the value in table 3 because of rounding of numbers.

Table 15. Simulated predevelopment and transient (1967–2010) groundwater budgets for the Bicycle Basin groundwater-flow model, Fort Irwin NatioCalifornia.—Continued[Units are in acre-feet]
88 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 26. Simulated ground-water budget components for the Bicycle Basin groundwater-flow model, Fort Irwin National 

Training Center, California: A, recharge; B, pumpage; C, outflow from drains; and changes in D, net delayed interbed storage; E, net 

instantaneous interbed storage; and F, groundwater storage.

sac11-0424_fig 26abc

A

B

C

Monthly recharge, in acre-feet per month Monthly pumpage, in acre-feet Monthly outflow from drains, in acre-feet 

Cumulative recharge, in acre-feet Cumulative pumpage,

in thousands of acre-feet

Cumulative outflow from drains, in acre-feet

1962 1967 1972 1978 1983 1989 1994 2000 2005 2011

1962 1967 1972 1978 1983 1989 1994 2000 2005 2011

0

10

20

30

40

50

0

50

100

150

200

250

300

0

2

4

6

8

10

12

1962

0

500

1,000

1,500

2,000

2,500

1967 1972 1978 1983 1989 1994 2000 2005 2011

0

1,000

2,000

3,000

4,000

5,000

6,000

0

2

4

6

8

10

12

Monthly

Cumulative

EXPLANATION

Monthly

Cumulative

EXPLANATION

Monthly

Cumulative

EXPLANATION
Groundwater-Flow Model 89

sac11-0424_fig 26def

DEFMonthly net delay interbed storage change, 

in acre-feet

Monthly net no-delay interbed 

storage change, in acre-feet

Monthly groundwater storage change, 

in acre-feet 

Cumulative net delay interbed 

storage change, in acre-feet

Cumulative net instantaneous interbed 

storage change, in acre-feet

Cumulative groundwater storage change,

in thousands of acre-feet

1962 1967 1972 1978 1983 1989 1994 2000 2005 2011

1962 1967 1972 1978 1983 1989 1994 2000 2005 2011

1962 1967 1972 1978 1983 1989 1994 2000 2005 20110

100

200

300

400

500

600

700

800

02468

10

12

14

16

500

200

150

200

250

300

350

0.0

1.0

2.0

3.0

4.0

−50

−40

−30

−20

−10 0

10

20

−300

−250

−200

−150

−100

−500

50

Monthly

Cumulative

EXPLANATION

Monthly

Cumulative

EXPLANATION

Monthly

Cumulative

EXPLANATION

Figure 26. —Continued
90 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Model Limitations

The use of numerical models to simulate hydrologic 

systems has inherent limitations. Limitations of the modeling 

software, data, assumptions made during model development, 

conceptual model error (Bredehoeft, 2005), and model 

calibration and sensitivity analysis are all factors that constrain 

the appropriate use of hydrologic models, including the 

Bicycle Basin model. Differences between simulated and 

actual hydrologic conditions arise from a number of sources 

and are known collectively as model error (Walter and 

Whealan, 2005).

The accuracy and reliability of model results are related 

to the quality and distribution of available data. In the Bicycle 

Basin model, uncertainties primarily resulted from limited 

available spatial and temporal data to characterize aquifers 

and calibrate for water-level variations and subsidence. For 

example, hydraulic properties (hydraulic conductivity, vertical 

anisotropy, specific yield, and specific storage) were estimated 

and applied over groups of many cells (parameter zones) 

because of the limited areal distribution of wells with detailed 

lithologic or borehole geophysical data. Detailed data on the 

extent, thickness, and hydraulic properties of the fine-grained 

interbeds needed to simulate subsidence accurately also were 

limited for the basin. A more complete distribution of multicompletion well sites with detailed lithology and borehole 

geophysical data would improve the aquifer characterization 

and the accuracy of simulating water levels as well as 

subsidence. 

Other limitations and assumptions that can contribute to 

uncertainty in the model include the following:

• Average recharge values were used throughout the 

simulation period because it was assumed the thick 

unsaturated zone smoothed the temporal variations 

in infiltration to long-term-average deep-percolation 

rates. 

• The quantity and distribution of pumpage for 1967–90 

were estimated from limited measured pumpage data 

for that period.

• Recharge and runoff estimated from the BCM, which 

also has assumptions and limitations, adequately 

simulated the actual recharge and runoff to the basin. 

• The sum of 10 percent of runoff draining into Bicycle 

Lake Basin and 100 percent of recharge in surrounding 

watersheds (moving in the subsurface to the study 

area) estimated by the BCM was a reasonable 

representation of the quantity of recharge in the basin.

• Vertical changes in land surface estimated from InSAR 

accurately represented subsidence in the Bicycle Basin.

• InSAR interferogram interpretations to determine 

land-surface deformation observations used for model 

calibration were reasonable.

The Bicycle Basin model synthesized the current data 

and understanding of the Bicycle Basin. The overall fit of the 

model to measured data (water levels and subsidence) was 

reasonable. The purpose for developing the Bicycle Basin 

groundwater-flow model was to provide a tool to help evaluate 

water-management strategies. When applied carefully, the 

groundwater-flow model of the Bicycle Basin can be used for 

simulating groundwater response to changes in stress to the 

groundwater-flow system. Uncertainty increases as simulated 

future stresses differ from historical stresses used in model 

calibration. Water-level and subsidence monitoring during any 

future management activities allow for recalibration of the 

model under different stress regimes. The model is most suited 

for comparison among scenarios rather than for accurately 

indicating the magnitude of future changes in water levels or 

subsidence.

Simulated Effects of Runoff Capture 

and Future Pumpage

The Bicycle Basin groundwater-flow model was used to 

evaluate changes in groundwater levels and subsidence under 

five water-management scenarios (table 16). These included 

capture of runoff into recharge basins (scenario 1) and various 

amounts and distributions of future pumpage (scenarios 2–5). 

The simulation period for the runoff-capture scenario was 

the same as the calibration period (predevelopment through 

2010). The pumpage scenarios were extended 50 years from 

2011 to 2060 (table 16). To evaluate 2010 pumpage and 

establish a base case, scenario 2 assumed that 2010 pumping 

rates continued in the same pumped wells. Pumpage was 

reduced to zero in well 14N/3E-14P1, and 2010 pumpage 

continued in the two production wells that were not in the 

area of subsidence (scenario 5). To evaluate the effect of 

pumpage changes in the area of subsidence, 2010 pumpage 

was reduced by 25 percent in well 14N/3E-14P1 and 

redistributed to the two production wells that were not in the 

area of subsidence (scenario 3). To evaluate reduced pumpage 

basin wide, scenario 4 was the same as scenario 3, with an 

additive reduction in basin-wide pumpage by 3 percent each 

year through 2020; the resulting 2020 pumpage was used 

through 2060.
Simulated Effects of Runoff Capture and Future Pumpage 91

Scenario 1: Simulated Effects of Captured Runoff

The Bicycle Basin groundwater-flow model was used 

to evaluate changes in groundwater-level altitudes and 

subsidence with the addition of runoff capture (scenario 1) 

not accounted for in the groundwater-flow model. For the 

groundwater-flow model without runoff capture, it was 

assumed that 10 percent of the runoff calculated by the BCM 

contributed to recharge of the groundwater-flow system; the 

remaining 90 percent was assumed to flow to the Bicycle 

Lake (dry) playa and evaporate. For scenario 1, the 90 percent 

of runoff was assumed to be captured for managed aquifer 

recharge using various approaches, such as diversion to 

retention basins. Recharge rates for the captured runoff were 

assigned to one model cell in each recharge zone representing 

recharge in retention basins in recharge zones 3–11 for the 

months with runoff. Captured runoff in recharge zones 1 and 

2 was distributed to two cells in each zone (fig. 27A). Table 17

shows the dates of runoff, the amounts of total runoff, runoff 

available for capture, and runoff used for capture in the model 

according to recharge zone in scenario 1. It was assumed 

that all of the available runoff could be captured for recharge 

during the simulation period (zero runoff flowing to the playa), 

except in 2010. Total runoff (the infiltrated runoff and the 

runoff that flowed to the playa) calculated by the BCM for 

2010 was about 59,300 acre-ft; in comparison, the total runoff 

calculated for 1967–2009 was about 1,480 acre-ft. Given the 

anomalous runoff for 2010, it was assumed that all of the 

available runoff for 2010 could be captured only in March, 

April, October, and November in the recharge zones with 

runoff (table 17). In addition, it was assumed that all of the 

available runoff could be captured in recharge zones 4–11 in 

January and recharge zones 4–9 in February. Available runoff 

in January, February, and December for recharge zones 1, 

2, and 3 and available runoff in December for recharge 

zones 4–11 was reduced to avoid simulation of unreasonable 

water levels. In recharge zone 1, where the water-bearing 

units are thinner and the hydraulic conductivity comparatively 

low, it was assumed that 0.5 percent of the available runoff 

could be captured in January and December, and 1 percent in 

February. In recharge zone 2, which had the largest quantity 

of runoff, and recharge zone 3, it was assumed that 10 percent 

of the available runoff could be captured during January, 

February, and December. In recharge zones 4–11, it was 

assumed 10 percent of the available December runoff could 

be captured. The 2010 runoff for recharge zones 1, 2, and 3 in 

January, February, and December not captured for managed 

aquifer recharge was assumed to flow to the playa. Although 

the model was insensitive to changes in recharge (table 14), 

the runoff for 2010 was more than the long-term average 

runoff, and all the recharge in Scenario 1 was focused in one 

or two cells, resulting in a substantial rise in water levels in the 

vicinity of focused recharge. These runoff-capture assumptions 

may be idealized and not easily implemented because runoff 

is highly episodic over long periods; retention basins could be 

difficult to maintain over these time spans.

Results for scenario 1 are presented as total values of 

groundwater-budget components in table 18 and as simulated 

drawdown maps for layers 1 and 6 in figure 27A–D. The small 

differences in well losses and pumping can be attributed to 

numerical computations associated with the multi-node wells. 

To prevent cells from going dry, pumping was reduced. For 

the simulation with runoff capture, water levels were higher 

than without runoff capture, so pumpage was not reduced 

and well losses increased. A positive value of drawdown 

indicated simulated heads declined from predevelopment to 

2010; a negative value indicated simulated heads increased 

for the same period. The difference in simulated drawdown 

(fig. 27C, D) was calculated by subtracting the values for 

scenario 1 from the values for the model without runoff 

capture. The simulated subsidence from 1993 through 2010 

with runoff capture and the difference between subsidence for 

scenario 1 and the model without runoff capture are presented 

in figures 28A and B, respectively.

Table 16. Runoff-capture and pumping-management scenarios, 

2010–60, for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California.

Scenario Simulation 

period Description

1 predevelopment

–2010

Capture of runoff was simulated by 

adding runoff calculated by the 

Basin Characterization Model 

(BCM ) that was not included as 

recharge in the model to specified 

cells within stream channels.

2 2011–60 Pumpage for active wells in 2010 

was repeated for each monthly 

stress period from 2011 through 

2060.

3 2011–60 Pumpage in well 14N/3E-14P1 was 

reduced by 25 percent with the 

pumpage distributed to production 

wells 14N/3E-13M1 and 14N/4E18N1 according to the percentage 

of total pumpage for both wells 

for each month; the adjusted 

monthly pumpage was repeated 

for each stress period from 2011 

through 2060.

4 2011–60 Same as scenario 3, with the added 

constraint of the cumulative 

reduction of annual basin 

pumpage by 3 percent per year for 

2011–20; the resulting pumpage 

was repeated from 2021 through 

2060.

5 2011–60 Same as scenario 2, except pumpage 

in well 14N/3E-14P1 was reduced 

to zero.
92 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 27. Location of runoff-capture cells for scenario 1 using the Bicycle Basin groundwater-flow model, Fort Irwin National Training 

Center, California, and A, simulated drawdown with runoff capture in December 2010 for model layer 1 and B, for model layer 6, and 

C, the difference between simulated drawdown with and without runoff capture for layer 1 and D, layer 6.

sac11-0424_fig 27ab

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

90

90

100

100

80

70

116°40’ 116°38’ 116°36’

35°18’ 35°16’

B

110

80

100 130

140

160

100

80

120

110

R. 3 E. R. 4 E.

T

14

N

100

0

20

40

20

40

100

60

60

60

60

0 20

0

120

160

0

80

20

40

80

120

40

60

20

18N2

18N1

24H1

23G1

22P1

14P2

14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

1 1

2

1 13

5 4

2

5

2

13

12

7

2

3

1

8 8

7

7

9

1

12

2

1

7

1

7 7

1

1 2

6

4

1

9

1

3

3

13

1 9

12

13

1

5

7

7

88

13

8

2

1

2

6

1

1

7

9

1

8

7

2

12

8 8

1

7

13

8

1

12

2

1

4

1

1

6

1

8

7

2

7

11

11

11

11

1010 10

10

10

A 116°40’ 116°38’ 116°36’ 35°18’ 35°16’

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

13

13

EXPLANATION

Simulated drawdown in model layer 6, 

in feet

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated fault

Simulated drawdown contours

 in model layer 6, in feet

Township/range

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Recharge cell and recharge-

 zone number

Runoff-capture cell

Parameter-zone boundary and 

 zone identifier

Simulated fault

Simulated drawdown contours

 in model layer 1, in feet

Township/range

−198 to −100

−99 to −50

−49 to 0

1 to 20

21 to 40

41 to 60

Simulated drawdown in model layer 1, 

in feet

61 to 80

81 to 100

101 to 120

121 to 140

141 to 160

161 to 180

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

62 to 70

71 to 80

81 to 100

101 to 120

121 to 130

131 to 140

141 to 150

151 to 160

161 to 170

171 to 188

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Zone 1

Zone 1

2

Production

Multiple-well

monitoring site

Well type and identifier (see table 1)

13K1

26K1 Destroyed

Test well

Obstructed

22P1

23G1

Production

Multiple-well

monitoring site

Well type and identifier (see table 1)

13K1

26K1 Destroyed

Test well

Obstructed

22P1

23G1

24H1

24H1

0 0.5 1 MILE

0 10.5 KILOMETER

No-flow

boundary

No-flow

boundary
Simulated Effects of Runoff Capture and Future Pumpage 93

Figure 27. —Continued

sac11-0424_fig 27cd

R. 3 E. R. 4 E.

T.

14

N.

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

116°40’ 116°38’ 116°36’

35°18’ 35°16’

D

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

90

0 C

EXPLANATION

1 to 5

6 to 10

11 to 15

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well type and identifier (see table 1)

Production

Multiple-well

monitoring site

Destroyed

Well type and identifier (see table 1)

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary 

 and zone identifier

Simulated fault

Township/range

Difference between simulated 

drawdown with and without recharge 

capture for model layer 6, in feet

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Recharge cell

Runoff-capture cell

Parameter-zone boundary 

 and zone identifier

Simulated fault

Township/range

0 to 5

6 to 10

11 to 25

26 to 50

Difference between simulated 

drawdown with and without recharge 

capture for model layer 1, in feet

51 to 75

76 to 100

101 to 150

151 to 205

16 to 20

21 to 26

13K1

22P1

26K1

13K1

23G1

22P1

26K1

Zone 1

Zone 1

Test well

24H1 Obstructed

23G1

24H1

No-flow

boundary

No-flow

boundary

0 0.5 1 MILE

0 10.5 KILOMETER

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6 Zone 7
Table 17A. Estimated total runoff for scenario 1 by the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California. [See figure 27A for location of recharge zones. Total runoff is in cubic feet.] Recharge zone December 1984 February 1992 January 1993 February 1993 January 1995 February 1998 January 2010 February 2010 March 2010 April 2010 October 2010 

1 1,829 0 92,320 24,867,921 0 0 232,497,534 111,094,662 6,951 169,063 87,145 

2 0 52,700 2,264,451 26,722,792 20,235 0 512,304,361 213,942,272 0 6,192,452 0 

3 0 0 0 573,380 0 0 23,522,987 10,544,208 0 0 0 

4 0 0 0 37,098 0 0 2,401,978 1,153,117 0 0 0 

5 0 0 0 430,422 0 0 2,734,209 1,278,878 0 0 0 

6 0 0 0 162,705 0 0 2,138,046 955,452 0 0 0 

7 0 0 0 0 0 0 2,790,666 213,601 0 0 0 

8 0 0 783,685 2,100,975 81,711 80,090 4,128,139 761,571 0 33,107 0 

9 0 0 717,446 1,865,797 73,140 73,963 4,046,040 894,463 0 82,253 0 

10 0 0 425,453 1,408,812 7,490 27,906 1,396,067 0 0 0 0 

11 0 0 356,947 1,428,736 1,105 4,224 799,672 0 0 0 0 

Table 17B. Estimated runoff available for capture for scenario 1 by the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, C[See figure 27A for location of recharge zones. Available runoff in this table is 90 percent of total runoff in table 17A. Runoff available for capture in cubic feet.] Recharge zone December 1984 February 1992 January 1993 February 1993 January 1995 February 1998 January 2010 February 2010 March 2010 April 2010 October 2010 

1 1,646 0 83,088 22,381,129 0 0 209,247,780 99,985,196 6,256 152,157 78,430 

2 0 47,430 2,038,006 24,050,513 587 0 461,073,925 192,548,045 0 5,573,206 0 

3 0 0 0 516,042 0 0 21,170,688 9,489,787 0 0 0 

4 0 0 0 33,388 0 0 2,161,780 1,037,805 0 0 0 

5 0 0 0 387,380 0 0 2,460,788 1,150,990 0 0 0 

6 0 0 0 146,435 0 0 1,924,241 859,907 0 0 0 

7 0 0 0 0 0 0 2,511,600 192,241 0 0 0 8 0 0 705,317 1,890,878 73,540 72,081 3,715,325 685,414 0 29,797 0 

9 0 0 645,701 1,679,218 65,826 66,567 3,641,436 805,017 0 74,028 0 

10 0 0 382,908 1,267,930 6,741 25,115 1,256,460 0 0 0 0 

11 0 0 321,252 1,285,862 995 3,801 719,705 0 0 0 0 
Table 17C. Estimated actual runoff rate applied to the runoff-capture model cells for scenario 1 by the Bicycle Basin groundwater-flow model, Fort ICenter, California.[See figure 27A for location of recharge zones. Runoff values in this table (in cubic feet) are divided by the number of days in the month and the area of the model cell (250,000 recharge rate for model input in feet per day.]

Recharge 

zone

December

1984

February

1992

January

1993

February

1993

January

1995

February

1998

January

2010

February

2010

March 

2010

April

2010

October

2010

1 1,646 0 83,088 22,381,129 0 0 11,046,239 2999,852 6,256 152,157 78,430 

2 0 47,430 2,038,006 24,050,513 587 0 346,107,392 319,254,804 0 5,573,206 0 3 0 0 0 516,042 0 0 32,117,069 3948,979 0 0 0 4 0 0 0 33,388 0 0 2,161,780 1,037,805 0 0 0 

5 0 0 0 387,380 0 0 2,460,788 1,150,990 0 0 0 6 0 0 0 146,435 0 0 1,924,241 859,907 0 0 0 7 0 0 0 0 0 0 2,511,600 192,241 0 0 0 8 0 0 705,317 1,890,878 73,540 72,081 3,715,325 685,414 0 29,797 0 

9 0 0 645,701 1,679,218 65,826 66,567 3,641,436 805,017 0 74,028 0 

10 0 0 382,908 1,267,930 6,741 25,115 1,256,460 0 0 0 0 

11 0 0 321,252 1,285,862 995 3,801 719,705 0 0 0 0 

1Runoff values are 0.5 percent of values in table 17B.2Runoff values are 1 percent of values in table 17B.3Runoff values are 10 percent of values in table 17B.

Table 18. Summary of simulated total groundwater budget, in acre-feet, for the Bicycle Basin groundwater-flow model, runoff-capture scenario (sce

pumpage scenarios (scenarios 2–5), Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California.

[Units are acre-feet; total values are for the end of the simulation period. Abbreviation: NA, not applicable]

Simulation period Recharge Captured runoff Well loss

Inflows Outflows 

No-delay 

interbed 

storage

Delay 

interbed 

storage

Total 

inflows Drains Pumpage

No-delay 

interbed 

storage

Delay 

interbed 

storage

Predevelopment through 2010 (historical period)

Calibrated model—without runoff-capture 5,104 NA 791 353 761 7,008 2,172 46,857 8.2 58 

Scenario 1—with runoff-capture 5,104 5,765 986 337 725 12,917 2,185 47,062 9.3 60 

2011 through 2060 (projected period)

 Scenario 2—base case 5,796 NA 187 439 1,213 7,635 0 54,628 3.9 135 

 Scenario 3 5,796 NA 236 419 1,139 7,590 0 54,529 3.2 107 

 Scenario 4 5,796 NA 183 337 881 7,198 0 41,477 3.6 103 

 Scenario 5 5,796 NA 199 147 365 6,508 0 27,239 2.4 11 
96 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

sac11-0424_fig 28ab

Simulated subsidence

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Simulated difference

in subsidence with and

without runoff capture, 

in feet

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Year

Simulated subsidence, in feet

A

B

Year

Simulated difference in subsidence with and 

without runoff capture, in feet

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

Figure 28. Simulated subsidence from the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California, A, for 

the runoff-capture scenario (scenario 1) and B, the difference between simulated subsidence with and without runoff capture.
Simulated Effects of Runoff Capture and Future Pumpage 97

Model results for scenario 1 indicated that total recharge 

for the simulation period, including natural recharge and 

runoff capture, was about 10,900 acre-ft; this was more than 

twice that of the model simulation without runoff capture. 

The total simulated groundwater-storage depletion was 

about 36,400 acre-ft, about 5,700 acre-ft less than the model 

simulation without runoff capture (table 18). Since the 

recharge of captured runoff did not substantially affect the 

other water-budget components, this value was similar to the 

amount of captured runoff.

In general, the distributions of simulated drawdown 

were similar for the model simulation without runoff capture 

(figs. 24A, B) and scenario 1 (figs. 27A, B); however, there 

were notable differences in the magnitude of simulated 

drawdown for both model layers 1 and 6. For example, the 

negative values of simulated drawdown in model layer 1 in the 

vicinity of recharge zone 1 for scenario 1 (fig. 27A) indicated 

that the simulated heads were higher in December 2010 

than in the predevelopment period. Simulated heads for 

the model without runoff capture in 2010 also were higher 

than the predevelopment period; however, the head change 

was less than in scenario 1. Negative values of drawdown 

also were simulated in model layer 1 near recharge zone 2 

for scenario 1 (fig. 27A). In this part of the basin, simulated 

heads were more than 100 ft higher in December 2010 

than in the predevelopment period. In contrast, simulated 

heads for the model without runoff capture were 80–90 ft 

lower in December 2010 than in the predevelopment period 

(fig. 24A). The largest differences in simulated drawdown 

between scenario 1 and the model without runoff capture 

for model layer 1 were primarily in parameter zone 1; the 

smallest differences in simulated drawdown were primarily in 

parameter zones 4–6 (fig. 27C).

The simulated runoff-capture scenario resulted in 

localized increases in water levels from predevelopment to 

2010 that partially offset depletion of groundwater due to 

pumping; the total depletion for this period was reduced by 

14 percent, indicating the overall effectiveness of this scenario. 

Although the distribution of drawdown in model layer 6 

for scenario 1 (fig. 27B) was similar to that for the model 

without runoff capture (fig. 24B), the magnitude of simulated 

drawdown was slightly less for scenario 1. For example, in 

the area around wells 14N/4E-18N1–2 simulated drawdown 

ranged from 90 to 100 ft for scenario 1; for the model without 

runoff capture, the simulated drawdown ranged from about 

100 to 110 ft (fig. 24B). The largest difference in simulated 

drawdown between scenario 1 and the model without runoff 

capture was in parameter zone 1; the smallest difference was 

in the southern part of parameter zone 5 (fig. 27D). 

Results for the simulated runoff-capture scenario 

indicated only modest decreases in subsidence compared 

with the overall magnitude of subsidence. Figure 28A shows 

simulated subsidence for scenario 1, and figure 28B shows the 

difference between scenario 1 and the model without runoff 

capture. The positive values for the difference in subsidence 

indicated that subsidence was less in scenario 1 than in 

the model simulation without runoff capture. Subsidence 

was mitigated somewhat by runoff capture (fig. 21B, 28A); 

the largest decrease in subsidence was about 0.052 ft at 

monitoring well site 14N/3E-23B1–3; the smallest decrease 

was about 0.017 ft at 14N/3E-23G1 (fig. 28B). The large 

quantity of runoff in 2010 resulted in a sharp decrease in 

subsidence beginning in January 2010. The maximum rate 

of subsidence at monitoring well site 14N/3E-23B1–3 in 

scenario 1 was 0.98 ft (fig. 28A) compared with a value 

of 1.03 ft for the model simulation without runoff capture 

(fig. 21B); thus, the simulated recharge of captured runoff 

resulted in a 5 percent decrease in subsidence at this site.

Simulated Effects of Future Pumpage

The groundwater-flow model was extended from 2011 

through 2060 and used to simulate the effects of four future 

pumpage scenarios being considered by the Fort Irwin NTC 

(Chris Woodruff, Fort Irwin National Training Center, written 

commun., 2011). Scenario 2 was a base case that continued 

2010 conditions for comparison with scenarios 3–5, which 

had alternate groundwater-pumping conditions (table 16). The 

groundwater-recharge rate for all the pumpage scenarios was 

assumed to be the same as in the historical period. 

Results of the future pumpage scenarios are presented 

as drawdown maps for model layer 6 from December 2010 

to December 2060 (figs. 29A–D). Results for model layer 6 

are shown because it represents the main aquifer contributing 

water to production wells in parameter zone 6, where land 

has subsided. A positive value for drawdown indicated the 

simulated hydraulic head declined during 2011–60.

Scenario 2

It was assumed for scenario 2 that annual pumpage 

in 2010 (1,090 acre-ft; table 3) remained constant during 

2011–60. The pumpage distribution to wells was based on 

the pumpage distribution for active production wells in 2010 

(14N/3E-13M1, 14N/3E-14P1, and 14N/4E-18N1; table 3). 

The monthly pumpage values in 2010 for these wells were 

repeated for monthly stress periods during 2011–60.

Model results for scenario 2 indicated that total pumpage 

for 2011–60 was about 54,600 acre-ft, and simulated 

groundwater-storage depletion was about 47,100 (table 18). 

Simulated drawdown in model layer 6 for 2011–60 ranged 

from about 46 ft to 135 ft (fig. 29A). Simulated drawdown 

in parameter zone 2 was primarily from pumping in well 

14N/3E-13M1, because the South Coyote Canyon fault 

(fig. 15) is a partial barrier to the effects of pumping in model 

layer 6 in the rest of the basin. Simulated drawdown was more 

than 120 ft near well 14N/4E-18N1 in parameter zone 1 and 

between 120 and 130 ft in parameter zones 3, 5, and 6.

Simulated drawdown near well 14N/4E-18N1 for 

2011–60 was greater than for well 14N/3E-14P1 (fig. 29A), 

even though the pumpage for well 14N/3E-14P1 was greater. 
98 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 29. Simulated drawdown in model layer 6 from the end of the historical period in December 2010 to the end of the projected 

period in December 2060 for the groundwater-flow model of the Bicycle Basin, Fort Irwin National Training Center, California, for 

A, scenario 2; B, scenario 3; C, scenario 4; and D, scenario 5 (see table 16 for description of the scenarios).

sac11-0424_fig 29ab

R. 3 E. R. 4 E.

T.

14

N.

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

B 35°18’ 35°16’

116°40’ 116°38’ 116°36’

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

70

110

120

130

110

110

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

50

120

110

A

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

120

120

EXPLANATION

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 6, in feet

Simulated fault

Township/range

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well type and identifier (see table 1)

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 6, in feet

Simulated fault

Township/range

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well type and identifier (see table 1)

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Simulated drawdown in model 

layer 6, in feet (variable interval)

46 to 51

105 to 110

111 to 120

121 to 130

131 to 135

Simulated drawdown in model 

layer 6, in feet (variable interval)

58 to 60

61 to 67

68 to 110

111 to 120

121 to 140

141 to 159

13K1

23G1

22P1

26K1

13K1

23G1

22P1

26K1

Zone 1

Zone 1

24H1

24H1

No-flow

boundary

No-flow

boundary
Simulated Effects of Runoff Capture and Future Pumpage 99

sac11-0424_fig 29cd

R. 3 E. R. 4 E.

T.

14

N.

0 0.5 1 MILE

0 10.5 KILOMETER

Base modified from U.S. Geological Survey and other Federal digital 

data, various scales; Universal Transverse Mercator, zone 11; 

North American Datum of 1983

D 35°18’ 35°16’

116°40’ 116°38’ 116°36’

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1 13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

30

20

10

0

30

30

0

R. 3 E. R. 4 E.

T.

14

N.

116°40’ 116°38’ 116°36’

35°18’ 35°16’

18N2

18N1

24H1

23G1

22P1

14P2 14P1

14H1

13K1

24Q1–5

23B1–3

26K1,3,4

13M1

13M2–4

40

80

70

C

70

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 6, in feet

Simulated fault

Township/range

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well type and identifier (see table 1)

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

EXPLANATION

Bicycle groundwater basin

Model boundary

Model grid

Parameter-zone boundary and 

 zone identifier

Simulated drawdown contours

 in model layer 6, in feet

Simulated fault

Township/range

Fault

motion

Sinistral

Thrust

Mapped

fault

Model-inferred

fault

Simulated drawdown in model 

layer 6, in feet (variable interval)

−8 to 0

1 to 10

11 to 20

21 to 30

31 to 37

Simulated drawdown in model 

layer 6, in feet (variable interval)

29 to 40

60 to 70

71 to 75

76 to 80

81 to 85

86 to 90

Production

Multiple-well monitoring site

Destroyed

Test well

Obstructed

Well type and identifier (see table 1)

13K1

23G1

22P1

26K1

13K1

23G1

22P1

26K1

Zone 1

Zone 1

24H1

24H1

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

No-flow

boundary

No-flow

boundary

Figure 29. —Continued
100 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

This reflects the differences in hydraulic properties in 

parameter zones 1 and 6, the release of water from storage 

by compaction of fine-grained interbeds in parameter zone 6, 

and the distribution of pumpage to the model layers. The high 

hydraulic conductivity in model layer 6 of parameter zone 6 

(33 ft/d) allowed the drawdown to be distributed over a larger 

area around 14N/3E-14P1; this could influence drawdown 

near well 14N/4E-18N1 and account for the comparatively 

high drawdown in the southwestern part of parameter 

zone 5 (fig. 29A).

Continuation of the 2010 pumpage resulted in continued 

decline in simulated heads through 2060 for the three wells, 

14N/4E-18N1, 14N/3E-13M1, and 14N/3E-14P1, shown 

in figure 30A–C, respectively. At well 14N/4E-18N1, the 

simulated heads in all layers at the end of 2011–60 declined 

below the bottom elevation of layer 3; layers 1–3 were 

dewatered near the well. The deeper layers have lower 

transmissivity values, so the seasonal fluctuations in the 

simulated heads became more pronounced as the simulated 

heads declined into these layers (fig. 30A).

Simulated heads at well 14N/3E-13M1 indicated that 

model layer 2 was dewatered early during 2011–60 (fig. 30B). 

Pumpage was substantially less for this well than for wells 

14N/4E-18N1 and 14N/3E-14P1, resulting in less drawdown. 

The seasonal fluctuations were less pronounced than for well 

14N/4E-18N1 because of the higher transmissivity values 

below model layer 2 near well 14N/3E-13M1.

Simulated heads at well 14N/3E-14P1 indicated that 

model layer 4 was dewatered during 2011–60. The difference 

in simulated heads between model layers 5 and 6 increased 

during 2011–60 (fig. 30C). The increased vertical gradient 

from pumpage in model layer 6 could have resulted from 

release of groundwater by compaction of fine-grained 

interbeds in model layer 5 and induced lateral flow into 

parameter zone 6; this also probably helped to damp the 

seasonal fluctuations in simulated water levels in model 

layer 6.

Subsidence continued at all observation locations with 

the projection of 2010 pumpage to 2060 (fig. 31A). Total 

subsidence at the end of 2011–60 ranged from 0.83 ft at 

well 14N/3E-23G1 to 2.8 ft at monitoring well site 14N/3E23B1–3. The increase in simulated subsidence since 2010 

was smallest at well 14N/3E-23G1 (0.53 ft) and largest at 

well site 14N/3E-23B1 (1.73 ft). The rate of measured and 

simulated subsidence began to decrease after 2006, and 

the simulated rate continued to decrease during 2011–60 

(fig. 31A). This decrease in the rate of subsidence likely was 

due to lower annual pumpage during 2007–10 (1,125 acre-ft) 

compared with the average annual pumpage for the subsidence 

observation period of 1993–2010 (1,469 acre-ft; table 15).

Scenario 3

Scenario 3 assumed that pumpage for each month in 

2010 for well 14N/3E-14P1 was reduced by 25 percent, 

with the reduced quantity distributed to production wells 

14N/3E-13M1 and 14N/4E-18N1. The adjusted pumpage for 

2010 was repeated for each stress period during 2011–60. 

The quantity distributed to production wells 14N/3E-13M1 

and 14N/4E-18N1 was based on the percentage of total 

monthly 2010 pumpage attributed to wells 14N/3E-13M1 and 

14N/4E-18N1. The pumpage redistributed from well 14N/3E14P1 to well 14N/3E-13M1 ranged from 6 percent in July 

to 35 percent in November, and the pumpage redistributed 

to 14N/4E-18N1 was 94 percent and 65 percent for July 

and November, respectively. The pumpage for 2010 for 

well 14N/3E-14P1 was decreased by an average of about 

137 acre-ft, resulting in average annual increased pumpage 

of about 30 acre-ft for well 14N/3E-13M1 and of about 

110 acre-ft for well 14N/4E-18N1.

Model results for scenario 3 indicated that total pumpage 

for 2011–60 was about 54,500 acre-ft, approximately 

99 acre-ft less than the base case. Total pumpage should 

be the same as the base case; the difference is due to 

numerical calculations in the MNW2 package. The simulated 

groundwater-storage depletion was about 47,000 acre-ft, about 

80 acre-ft less than the base case (table 18). The distribution of 

simulated drawdown in model layer 6 for scenario 3 (fig. 29B) 

differed from the base case (fig. 29A). Scenario 3 had less 

drawdown in parameter zones 3, 5, and 6 than the base case, 

reflecting the reduced pumping in well 14N/3E-14P1. The 

increase in pumping in wells 14N/3E-13M1 and 14N/4E-18N1 

resulted in greater drawdown in parameter zone 2 and in the 

vicinity of 14N/4E-18N1 (fig. 29B). 

Adjustment of the 2010 pumpage for 2011–60 resulted in 

continued decline in simulated heads through 2060 (fig. 32), 

which generally were similar to the base case (fig. 30). The 

additional pumpage for 14N/34-18N1, however, resulted in 

larger seasonal fluctuations for scenario 3 than for the base 

case (figs. 32A, 30A, respectively) as layers 1–4 became 

dewatered and pumpage was redistributed to deeper layers 

with lower hydraulic conductivity. The additional pumpage for 

well 14N/4E-18N1 resulted in simulated heads that were as 

much as 50 ft lower than in the base case at the end of 2060.

The additional pumpage for well 14N/3E-13M1 resulted 

in greater decline in simulated heads, and seasonal fluctuations 

were slightly more pronounced during 2011–60 than in the 

base case (figs. 32B, 30B, respectively). The simulated heads 

at the end of this period for scenario 3 were as much as about 

20 ft lower than for the base case.

The reduction in pumpage for well 14N/3E-14P1 resulted 

in less simulated head decline and slightly less pronounced 

seasonal fluctuations compared with the base case (figs. 32C, 

30C, respectively). The difference in simulated heads between 

layers 5 and 6 was about 10 ft less than for the base case at 

the end of 2060; the simulated heads were about 5 ft and 15 ft 

higher for layers 5 and 6, respectively, in scenario 3 than in the 

base case. 

Subsidence continued at all observation locations with 

the adjusted 2010 pumpage during 2011–60 (fig. 31B). 
Simulated Effects of Runoff Capture and Future Pumpage 101

sac11-0424_fig 30ab

Land-surface altitude = 2,422 feet

Top of model

Land-surface altitude = 2,382 feet

Top of model

EXPLANATION

Simulated hydraulic head model layer

3

4

5

6

7

8

Top and bottom of model layer

Measured water level (14N/4E-18N1S)

Measured water level (14N/4E-18N2S)

2

3

4

5

6

7

Simulated hydraulic head model layer Top and bottom of model layer

Measured water level (14N/3E-13M1S)

EXPLANATION

Bottom of layer 6 = 1,844 feet

Bottom of layer 5 = 1,973 feet

Year

Altitude, in feet

A

Year

Altitude, in feet

B

1,850

1,900

1,950

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2062 2062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 1

Layer 2

Layer 3

Layer 5

Layer 6

Layer 4

Figure 30. Measured groundwater levels during the historical period and simulated heads for scenario 2 during the historical and 

projected periods for the Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California, in wells A, 14N/4E18N1,2; B, 14N/3E-13M1; and C, 14N/3E-14P1.
102 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 30. —Continued

sac11-0424_fig 30c

Land-surface altitude = 2,393

Top of model

Bottom of layer 6 = 1,865 feet

EXPLANATION

Simulated hydraulic head model layer

5 6

Top and bottom of model layer

Measured water level (14N/3E-14P1S)

Year

Altitude, in feet

C

1,950

2,000

2,050

2,100

2,150

2,200

2,250

196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008201020122014201620182020202220242026202820302032203420362038204020422044204620482050205220542056205820602062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6
Simulated Effects of Runoff Capture and Future Pumpage 103

Figure 31. Observed land-surface deformation from 1993 through 2010 and simulated subsidence from 1993 through 2060 for the 

Bicycle Basin groundwater-flow model, Fort Irwin National Training Center, California, for A, scenario 2; B, scenario 3; C, scenario 4; and 

D, scenario 5.

sac11-0424_fig 31ab

Simulated

subsidence

Observed 

land-subsidence

deformation

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S, 

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Simulated

subsidence

Observed 

land-subsidence

deformation

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S, 

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Year

Subsidence, in feet

A

B

199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Year

Subsidence, in feet

199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2062 2062
104 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Figure 31. —Continued

sac11-0424_fig 31cd

Simulated

subsidence

Observed 

land-subsidence

deformation

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S, 

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Simulated

subsidence

Observed 

land-subsidence

deformation

EXPLANATION

14N/3E-14P1S

14N/3E-23B1S, 

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

14N/3E-14P1S

14N/3E-23B1S,

 -23B2S, -23B3S

14N/3E-23G1S

Point 1

Point 2

Point 3

Year

Subsidence, in feet

C

D

199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Year

Subsidence, in feet

199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2062 2062
Simulated Effects of Runoff Capture and Future Pumpage 105

Figure 32. Measured groundwater levels and simulated heads for scenario 3 for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California, in production wells A, 14N/4E-18N1,2; B, 14N/3E-13M1; and C, 14N/3E-14P1.

sac11-0424_fig 32ab

Land-surface altitude = 2,422 feet

Top of model

Land-surface altitude = 2,382 feet

Top of model

2

3

4

5

6

7

Simulated hydraulic head model layer Top and bottom of model layer

Measured water level (14N/3E-13M1S)

EXPLANATION

EXPLANATION

Simulated hydraulic head model layer

3

4

5

6

7

8

Top and bottom of model layer

Measured water level (14N/4E-18N1S)

Measured water level (14N/4E-18N2S)

Bottom of layer 6 = 1,844 feet

Bottom of layer 5 = 1,973 feet

Year

Altitude, in feet

A

Year

Altitude, in feet

B

1,850

1,900

1,950

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2062 2062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6
106 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Subsidence at the end of this period ranged from 0.81 ft at 

well 14N/3E-23G1 to 2.69 ft at monitoring well site 14N/3E23B1–3. Well 14N/3E-23G1 had the smallest increase in 

subsidence (0.50 ft), and well site 14N/3E-23B1–3 had the 

largest increase (1.68 ft). The difference in total subsidence 

at the end of 2060 between the base case and scenario 3 was 

small, less than or equal to 0.07 ft for all observation points, 

indicating that changes in pumpage at well 14N/3E-14P1 

from this scenario would result in only limited reduction 

of subsidence.

Scenario 4

Scenario 4 assumed the same adjustments to 2010 

pumpage as scenario 3 (25 percent reduced pumpage from 

well 14N/3E-14P1 redistributed to wells 14N/3E-13M1 and 

14N/4E-18N1) with the added constraint of 3 percent per year 

reduction in total annual pumpage in the basin from 2011 

through 2020. The resulting pumpage for 2020 was repeated 

from 2021 through 2060. The annual pumpage for well 

14N/3E-14P1 ranged from 401 acre-ft for 2011 to 304 acre-ft 

for 2020–60. The annual pumpage for well 14N/4E-18N1 

ranged from 517 acre-ft in 2011 to 393 acre-ft for 2021–60. 

The annual pumpage for well 14N/3E-13M1 ranged from 

140 acre-ft in 2011 to 106 acre-ft for 2011–60.

The total pumpage for 2011–60 was about 41,500 acre-ft, 

or 13,200 acre-ft less than the base case. The simulated 

groundwater-storage depletion was about 34,400 acre-ft, 

12,700 acre-ft less than the base case (table 18). The 

distribution and magnitude of simulated drawdown in model 

layer 6 for scenario 4 (fig. 29C) was substantially different 

from the base case (fig. 29A) south of the South Coyote 

Canyon fault (fig. 15). North of the fault, the distribution of 

drawdown was similar to the base case, but the magnitude was 

substantially different. The drawdown near well 14N/4E-18N1 

was about 40 ft less than for the base case; near well 14N/4E14P1, drawdown was about 60 ft less than the base case.

The adjusted pumpage for scenario 4 resulted in 

continued decline in simulated heads during 2011–60 (fig. 33), 

similar to the base case (fig. 30). In contrast to the base case, 

however, simulated heads in well 14N/4E-18N1 for scenario 4 

were above the bottom of layer 3 for almost all of 2011–60. 

Although additional pumpage was distributed to well 14N/4E18N1, the reduction in overall basin-wide pumpage helped to 

mitigate dewatering of the upper layers, resulting in smaller 

seasonal fluctuations in well 14N/4E-18N1 (fig. 33A) than for 

the base case (fig. 30A). Simulated heads at the end of 2060 

in well 14N/4E-18N1 for scenario 4 were as much as about 

100 ft higher than for the base case.

The reduction in basin-wide pumpage also helped 

to mitigate the effects of the additional pumpage for 

well 14N/4E-13M1; however, the difference in the decline 

in simulated heads from the base case was less pronounced 

(figs. 33B, 30B, respectively). Simulated heads at the end of 

2060 in well 14N/4E-13M1 for scenario 4 were about 20 ft 

higher than for the base case. 

Figure 32. —Continued

sac11-0424_fig 32c

Land-surface altitude = 2,393 feet

Top of model

Bottom of layer 6 = 1,865 feet

EXPLANATION

Simulated hydraulic head model layer

5 6

Top and bottom of model layer

Measured water level (14N/3E-14P1S)

Year

Altitude, in feet

C

1,950

2,000

2,050

2,100

2,150

2,200

2,250

196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008201020122014201620182020202220242026202820302032203420362038204020422044204620482050205220542056205820602062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 6

Layer 5
Simulated Effects of Runoff Capture and Future Pumpage 107

sac11-0424_fig 33ab

Land-surface altitude = 2,422 feet

Top of model

Land-surface altitude = 2,382 feet

Top of model

EXPLANATION

Simulated hydraulic head model layer

3

4

5

6

7

8

Top and bottom of model layer

Measured water level (14N/4E-18N1S)

Measured water level (14N/4E-18N2S)

2

3

4

5

6

7

Simulated hydraulic head model layer Top and bottom of model layer

Measured water level (14N/3E-13M1S)

EXPLANATION

Bottom of layer 6 = 1,844 feet

Bottom of layer 5 = 1,973 feet

Year

Altitude, in feet

A

Year

Altitude, in feet

B

1,850

1,900

1,950

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2,000

2,050

2,100

2,150

2,200

2,250

196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008201020122014201620182020202220242026202820302032203420362038204020422044204620482050205220542056205820602062 2062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Figure 33. Measured groundwater levels and simulated heads for scenario 4 for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California, in production wells A, 14N/4E-18N1, 2; B, 14N/3E-13M1; and C, 14N/3E-14P1.
108 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The reduction in basin-wide pumpage combined with the 

reduction in pumpage for well 14N/3E-14P1 during 2011–60 

resulted in less overall decline in simulated heads in model 

layers 5 and 6 (fig. 33C) than in the base case (fig. 30C). 

Simulated heads at the end of 2060 in well 14N/3E-14P1 for 

scenario 4 were about 50 ft higher in model layer 5 and 60 ft 

higher in model layer 6 than for the base case. 

Subsidence continued at all observation locations with 

the adjusted pumpage for scenario 4 (fig. 31C), but at lower 

rates than in the base case (fig. 31A). Subsidence at the end 

of 2060 ranged from 0.83 ft at well 14N/3E-23G1 to 2.8 ft 

at monitoring well site 14N/3E-23B1–3. Well 14N/3E-23G1 

had the smallest increase in subsidence since December 2010 

(0.40 ft), and monitoring well site 14N/3E-23B1–3 had the 

largest increase (1.29 ft). The total subsidence during 2011–60 

was between 0.12 and 0.43 ft less at well 14N/3E-23G1 and 

well site 14N/3E-23B1–3, respectively, for scenario 4 relative 

to the base case, indicating that changes in pumpage for this 

scenario could result in reduction of subsidence.

Scenario 5

Scenario 5 assumed that the distribution of the pumpage 

to wells 14N/4E-18N1 and 14N/3E-13M1 was the same as in 

the base case; the 2010 pumpage was constant for these wells 

during 2011–60. The pumpage for well 14N/3E-14P1 was 

reduced to zero for this period, resulting in less total pumpage 

for this scenario than for the base case.

The total pumpage for 2011–60 was about 27,200 acre-ft, 

about half of the pumpage for the base case (table 18). 

The simulated groundwater-storage depletion was about 

20,700 acre-ft, about 56 percent less than the base case. The 

distribution and magnitude of simulated drawdown in model 

layer 6 for scenario 5 (fig. 29D) was much different from the 

base case (fig. 29A). The negative values near well 14N/3E14P1 indicated the simulated heads increased by as much as 

8 ft during 2011–60. In the eastern part of parameter zone 

1 near 14N/4E-18N1, drawdown was less than 40 ft. In 

comparison, simulated drawdown near 14N/4E-18N1 for the 

base case ranged from 110 to 135 ft (fig. 29A). The difference 

in drawdown near well 14N/4E-18N1 between scenario 5 

and the base case indicated that pumping in well 14N/3E14P1 substantially affected simulated heads in this area. In 

parameter zone 2, simulated drawdown was about 15 ft less 

than in the base case.

Simulated heads in well 14N/4E-18N1 remained above 

the bottom of model layer 3 during 2011–60 (fig. 34A). The 

damped seasonal simulated-head fluctuations for this period 

likely were due to less drawdown and the associated greater 

overall transmissivity than in the base case. The simulated 

heads at the end of 2060 in well 14N/4E-18N1 were as much 

as 120 ft higher in model layer 8 than in the base case.

Figure 33. —Continued

sac11-0424_fig 33c

Land-surface altitude = 2,393 feet

Top of model

Bottom of layer 6 = 1,865 feet

EXPLANATION

Simulated hydraulic head model layer

5 6

Top and bottom of model layer

Measured water level (14N/3E-14P1S)

Year

Altitude, in feet

C

1,950

2,000

2,050

2,100

2,150

2,400

2,500

196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008201020122014201620182020202220242026202820302032203420362038204020422044204620482050205220542056205820602062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6
Simulated Effects of Runoff Capture and Future Pumpage 109

sac11-0424_fig 34ab

Land-surface altitude = 2,422

Top of model

Land-surface altitude = 2,382

Top of model

EXPLANATION

Simulated hydraulic head model layer

3

4

5

6

7

8

Top and bottom of model layer

Measured water level (14N/4E-18N1S)

Measured water level (14N/4E-18N2S)

2

3

4

5

6

7

Simulated hydraulic head model layer Top and bottom of model layer

Measured water level (14N/3E-13M1S)

EXPLANATION

Bottom of layer 6 = 1,844 feet

Bottom of layer 5 = 1,973 feet

Year

Altitude, in feet

A

Year

Altitude, in feet

B

1,850

1,900

1,950

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2,000

2,050

2,100

2,150

2,200

2,250

19621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012201420162018202020222024202620282030203220342036203820402042204420462048205020522054205620582060

2062 2062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Figure 34. Measured groundwater levels and simulated heads for scenario 5 for the Bicycle Basin groundwater-flow model, Fort Irwin 

National Training Center, California, in production wells A, 14N/4E-18N1, 2; B, 14N/3E-13M1; and C, 14N/3E-14P1.
110 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The simulated heads in well 14N/3E-13M1 for 

scenario 5 (fig. 34B) were not much different from the base 

case (fig. 30B). The difference in simulated heads between 

scenario 5 and the base case was less than 6 ft for all model 

layers, indicating that pumping in well 14N/3E-14P1 had 

little effect on simulated heads in parameter zone 2. The 

South Coyote Canyon fault (fig. 15) is a partial barrier to 

groundwater flow, which somewhat isolates parameter zone 2 

from pumping in the rest of the basin.

The absence of pumpage for well 14N/3E-14P1 during 

2011–60 allowed simulated heads in model layers 5 and 6 at 

this well to recover from drawdown caused by the pumping 

during the historical period (fig. 34C). In contrast to the base 

case, simulated heads in model layers 5 and 6 remained above 

the bottom of layer 2 during 2011–60. The difference in 

simulated heads between layers 5 and 6 was reduced by about 

40 ft (fig. 34C). The simulated heads at the end of 2060 in 

well 14N/3E-14P1 were about 90 ft and about 130 ft higher in 

model layers 5 and 6, respectively, than the base case. 

Subsidence continued during 2011–60 at all observation 

locations in the absence of pumping in well 14N/3E-14P1 

(fig. 31D), but at a much slower rate than in the base case 

(fig. 31A). At the end of 2060, subsidence ranged from 0.49 ft 

at 14N/3E-23G1 to 1.57 ft at monitoring well site 14N/3E23B1–3. Well 14N/3E-23G1 was the site of the smallest 

increase in subsidence (0.19 ft) since December 2010, and the 

largest increase (0.56 ft) was at monitoring well site 14N/3E23B1–3. The simulated subsidence during 2011–60 ranged 

from about 0.19 to about 1.16 ft less at well 14N/3E-23G1 

and at well site 14N/3E-23B1–3, respectively, than in the 

base case, indicating that the discontinuation of pumpage at 

well 14N/3E-14P1 could substantially reduce subsidence.

Overall, continued declines in the water table dewatered 

the more productive upper layers of the aquifer, causing more 

pumpage to be withdrawn from deeper, lower yielding layers 

and resulting in increasing declines in the water table and 

greater vertical gradients in the future. The declines of the 

water table to the perforated intervals of wells could increase 

maintenance costs and alter the quality of water discharged 

from the wells. Water-management scenario 1 indicated that 

additional managed recharge resulted in a modest decrease 

(4–5 percent) in the rate of subsidence compared with 

historical conditions without managed recharge. The reduction 

of pumpage in the area of subsidence and redistribution of the 

amount of the reduction to wells in other parts of the basin 

(scenario 3) resulted in modest decreases (5–6 percent) in the 

rate of subsidence compared with continuation of historical 

pumping levels. Including a basin-wide reduction of pumpage 

of 3 percent annually for 10 years—a 24 percent total 

decrease in pumpage—along with the point-specific reduction 

and redistribution of pumpage (scenario 4) is predicted to 

produce a comparable decrease in additional subsidence 

(22–26 percent); however, a targeted decrease in pumpage 

for one well in the area of greatest subsidence (scenario 5) 

showed a predicted decrease in additional subsidence that was 

proportionally greater (62–68 percent) than the percent change 

in pumpage.

Figure 34. —Continued

sac11-0424_fig 34c

Land-surface altitude = 2,393

Top of model

Bottom of layer 6 = 1,865 feet

EXPLANATION

Simulated hydraulic head model layer

5 6

Top and bottom of model layer

Measured water level (14N/3E-14P1S)

Year

Altitude, in feet

C

1,950

2,000

2,050

2,100

2,150

2,200

2,250

196219641966196819701972197419761978198019821984198619881990199219941996199820002002200420062008201020122014201620182020202220242026202820302032203420362038204020422044204620482050205220542056205820602062

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6
Summary and Conclusions 111

Summary and Conclusions

Bicycle Basin is within the boundary of the Fort Irwin 

National Training Center (NTC), which is about 130 miles 

(mi) northeast of Los Angeles in the Mojave Desert region 

of southern California. The NTC covers an area of about 

1,177 square miles (mi2) that contains several surface-water 

drainage basins including Irwin, Bicycle, and Langford 

Basins. Bicycle Basin (groundwater basin) covers an area of 

about 10.5 mi2 that lies in the southeastern part of the much 

larger Bicycle Drainage Basin, an area of about 140 mi2. 

Bicycle Basin, typical of desert basins in the Mojave Desert, 

is a closed basin with a relatively flat floor surrounded by 

generally rugged mountains or low-lying hills. No perennial 

streams are present in the basin, but several washes flow for 

several days after large storms. The climate of Bicycle Basin, 

typical of the Mojave Desert region, is characterized by low 

precipitation; hot summers; and cool winters, during which 

most precipitation falls, except for the occasional isolated 

thunderstorms during the summer months.

Bicycle Basin is filled with as much as 2,300 feet (ft) 

of Tertiary sedimentary deposits, Quaternary older alluvium 

and clay, and Quaternary younger alluvium. These deposits 

are unconsolidated at and near land surface and become 

moderately to well consolidated with increasing depth and 

also have diminishing permeability and water quality with 

increasing depth. These deposits are surrounded and underlain 

by a bedrock complex consisting of pre-Tertiary granitic, 

metamorphic and volcanic rocks that is assumed to be nonwater-bearing because of the low permeability and limited 

water-storage characteristics of these rocks. The groundwater 

system in Bicycle Basin consists of two aquifers, referred to in 

this report as the upper aquifer and lower aquifer. The upper 

aquifer is composed of the younger and older Quaternary 

alluvium and clay. The lower aquifer is composed of younger 

and older Tertiary sedimentary deposits. Several faults mapped 

in the bedrock hills around Bicycle Basin, and splays off these 

faults, were projected into the basin using geophysical and 

gravity surveys and water-level measurements collected for 

this study. These splays act as partial barriers to groundwater 

flow through the basin fill.

Natural recharge in Bicycle Basin is from infiltration and 

underflow of precipitation and storm runoff along washes that 

drain watersheds surrounding the basin. During the period 

prior to development of groundwater resources of the basin, 

a similar quantity groundwater was thought to naturally 

discharge from the basin as groundwater underflow through 

fractured volcanic material and granitic bedrock southeast of 

the Bicycle Lake (dry) playa. Since groundwater development, 

the decline in groundwater levels is likely to have caused this 

natural discharge to cease. 

The first well in Bicycle Basin was drilled in 1955. 

Groundwater export to Irwin Basin began in 1967. 

Annual groundwater pumpage ranged from a low of about 

125 acre feet per year (acre-ft/yr) in 1977 to a high of about 

2,145 acre-ft/yr in 1998; pumpage in 2010 was 1,090 acre 

feet (acre-ft). Groundwater pumping in Bicycle Basin from 

1967 through 2010 resulted in water-level declines of as 

much as 100 ft; about 46,000 acre-ft of water was pumped 

from the basin and transported to the Irwin Basin. During 

1967–2010, groundwater pumping was substantially greater 

than the recharge of 5,400 acre-ft of underflow from adjacent 

watersheds and washes. Water quality of the groundwater 

pumped from some wells in the basin declined as well. 

Groundwater levels in Bicycle Basin have declined in 

response to increased pumpage, with relatively larger declines 

near areas of larger withdrawals. Continuous water-level 

data from multiple-well monitoring sites indicated that the 

water level (or hydraulic head) varied with depth in some 

areas, primarily showing groundwater moving from relatively 

shallower and deeper parts of the aquifer to the middle zones 

from which groundwater was withdrawn. 

During 2003–05, an earth fissure and sink-like 

depressions formed on Bicycle Lake (dry) playa, which 

is used as an aircraft runway for transporting troops and 

supplies to the base. Interferograms were used to identify 

areas affected, measure the amount of vertical displacement, 

and map the extent of subsidence in the basin. The area 

affected by subsidence was about 2.6 mi2

 that coincided with 

an area containing substantial clay deposits. The amount 

of vertical change was about 0.2–1.1 ft from 1993 to 2010. 

During 2003–06, subsidence rates were nearly double those 

of 1992–2000. Subsidence was the result of dewatering of 

the interbedded fine-grained materials due to groundwater 

pumping in the basin.

The chemistry of the recharge water and various 

geochemical reactions, including dissolution, precipitation 

of minerals in the subsurface, and evapoconcentration, 

controlled the major-ion chemistry of the groundwater in the 

Bicycle Basin. Water-quality samples from wells in Bicycle 

Basin indicated that groundwater types varied from sodiumbicarbonate-sulfate (NaHCO3

-SO4) type water and sodiumbicarbonate-chloride (NaHCO3

-Cl) type water, depending on 

the sulfate and chloride concentration, to sodium-chloride 

(NaCl) type water. Relatively poor groundwater quality, 

with higher total dissolved solids, primarily appeared to be 

associated with water withdrawn from wells perforated in 

Tertiary older alluvium. As groundwater levels in shallower 

aquifer zones were drawn down by continued pumping, 

deeper groundwater, such as from the Tertiary older alluvium, 

supplied more of the groundwater to wells, and this water 

was poorer quality than that of the shallower aquifer zones. 

Groundwater quality beneath playas generally results from 

lateral inflow from groundwater and remobilization of buried 

salts from evaporite deposits. High concentrations of total 

dissolved solids and chloride in some samples indicated 

that saline water could move laterally from the evaporite or 

playa deposits toward pumping depressions. Concentrations 

above the primary maximum contaminant level of arsenic and 

fluoride were measured in groundwater samples from wells in 

the area of greatest subsidence.
112 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

The stable isotopic concentration of oxygen-18 and 

deuterium/hydrogen-1, δ18O and δD, of water from sampled 

wells was isotopically lighter than that of available nearby 

modern-day precipitation, indicating most of the groundwater 

in the basin was recharged during a cooler and wetter period 

than present-day conditions. Samples for stable isotopes, δ18O 

and δD, indicated the source of groundwater was infiltration of 

storm runoff and underflow from the Granite Mountains to the 

north and the Goldstone upland area to the west. Groundwater 

from wells perforated in the Tertiary deposits generally was 

isotopically lighter than groundwater from wells perforated in 

the Quaternary, indicating that changes in climatic conditions, 

possibly including changes in storm trajectories, could have 

affected groundwater recharge rates and source areas in 

the past.

Nearly all groundwater samples from wells in Bicycle 

Basin contained no measurable concentrations of tritium (3H), 

indicating that water in most of the basin was recharged prior 

to 1952. Uncorrected 14C data indicated the groundwater in 

these wells had apparent ages of 15,625–39,350 years. These 

data indicated that the small amounts of recent recharge 

(since about 1950) have not yet reached the depths of the well 

perforations sampled in the Bicycle Basin.

A groundwater-flow model was developed to better 

understand the aquifer system and to assess the long-term 

availability of groundwater in the basin. The aquifer system 

was discretized vertically in eight model layers representing 

the different geologic units making up two aquifers. Boundary 

conditions, altitudes of the model-layer bottoms, distributions 

of hydraulic properties, and rates of recharge and discharge 

were determined using existing and newly collected 

geohydrologic data or were estimated if data were unavailable. 

The Bicycle Basin groundwater-flow model was 

calibrated by trial and error with an automated process of 

minimizing the differences between measured data and 

simulated output. Initial estimates of hydraulic properties, 

recharge and discharge, were modified to improve the matches 

between simulated hydraulic heads and measured water levels 

and between simulated subsidence and observed land-surface 

deformation. Although simulated heads generally matched 

measured water levels well, there were periods for which 

the model overestimated or underestimated measured water 

levels. Mismatches between simulated heads and measured 

water levels can be attributed to uncertainty in the estimated 

distribution of annual basin-wide pumpage to active wells 

for 1967–83, the estimated distribution of monthly pumpage 

from annual values for 1984–90, and the local variability in 

hydraulic properties that were not reflected in the model. In 

general, the simulated subsidence compared well with the 

observed land-surface deformation.

Simulated drawdown in model layer 1 in the Bicycle 

Basin ranged from no drawdown in the northwestern part 

of the basin to more than 100 ft north of the South Coyote 

Canyon fault and in the northeastern part of the basin. Total 

groundwater pumpage of about 47,000 acre-ft from 1967 

through 2010 resulted in drawdown of as much as 189 ft in 

model layer 6. The drawdowns in model layer 6 were larger 

than in model layer 1 because model layer 6 intersects the 

perforations of the five production wells, whereas model 

layer 1 only intersects the perforations of one production well.

Total groundwater-storage depletion (total inflows minus 

total outflows) was about 42,100 acre-ft. This indicates that 

about 91 percent of pumpage was supplied by depletion of 

groundwater storage, about 4.7 percent from reduced outflow 

from the basin, and about 2.3 percent from net instantaneous 

and delayed storage depletion.

The Bicycle Basin groundwater-flow model was used 

to simulate the effects of five water-management scenarios 

to assess long-term availability of groundwater relative to 

mitigation of declining water levels and continued subsidence 

in Bicycle Basin. These scenarios included capture of runoff 

that was not already accounted for in the model (scenario 1) 

and four future-pumpage scenarios (scenarios 2–5). The period 

for scenario 1 was the same as the groundwater-flow model 

without runoff capture, predevelopment through 2010. The 

calibrated model was extended from 2011 through 2060 for 

scenarios 2–5. 

Scenario 1 assumed that the 90 percent of runoff 

calculated by the Basin Characterization Model (BCM) 

not used for recharge in the groundwater-flow model was 

captured from drainage basins which had runoff during the 

simulation period, except for 2010. In 2010, the captured 

runoff was reduced for January, February, and December 

because of the large quantity of runoff simulated by the BCM 

model for these months. Model results indicated simulated 

groundwater-storage depletion was about 14 percent less 

than the model without runoff capture. All of the additional 

recharge thus effectively acted to reduce storage depletion. 

The distribution of simulated drawdown with captured runoff 

generally was similar to that without runoff capture; however, 

there were notable differences in the magnitude of simulated 

drawdown for model layers 1 and 6 in both simulations. For 

example, the simulated drawdown in model layer 1 near 

recharge zone 1 for scenario 1 indicated that the simulated 

heads were higher in December 2010 than before the onset 

of groundwater development; simulated heads without runoff 

capture also were higher, but the head change was much less 

than in scenario 1. In model layer 6, in the eastern part of 

the basin near recharge zone 2, simulated heads were more 

than 100 ft higher in December 2010 than before the onset 

of development. In contrast, simulated heads without runoff 

capture were 80–90 ft less in December 2010 than before the 

onset of development. The simulated runoff capture resulted 

in only modest decreases in subsidence compared with the 

magnitude of subsidence without runoff capture. 
Summary and Conclusions 113

Scenario 2 assumed the monthly pumpage for 2010 

continued for each stress period in the projected period; 

this scenario was considered the base case for comparison 

with the other future pumpage scenarios. Total pumpage 

for scenario 2 was about 54,600 acre-ft, and the simulated 

groundwater-storage depletion was about 47,100 for the 

projected period. Simulated drawdown in model layer 6 north 

of the South Coyote Canyon fault for 2011–60 ranged from 

46–51 ft to more than 120 ft in parameter zones 5 and 6 and 

near well 14N/4E-18N1. The difference between simulated 

drawdown in model layer 6 in parameter zone 2 and the rest 

of the basin indicated that the South Coyote Canyon fault 

effectively isolated parameter zone 2 from pumping in the 

rest of the basin. The largest simulated drawdown was near 

well 14N/4E-18N1, even though well 14N/3E-14P1 had larger 

pumpage, reflecting the differences in hydraulic properties in 

parameter zones 1 and 6, the release of water from storage by 

compaction of fine-grained interbeds in parameter zone 6, and 

the distribution of pumpage to the model layers. Subsidence 

continued at all observation locations; total subsidence 

ranged from 0.83 ft at 14N/3E-23G1 to 2.8 ft at well site 

14N/3E-23B1–3.

Scenario 3 assumed that pumpage for well 14N/3E14P1 was reduced by 25 percent, and the amount of the 

reduction was distributed to wells 14N/3E-13M1 and 14N/4E18N1. Model results for scenario 3 indicated that simulated 

groundwater-storage was depleted only about 80 acre-ft less 

than it was in the base case. The distribution of simulated 

drawdown in model layer 6 for scenario 3 indicated less 

drawdown in parameter zones 3, 5, and 6 than in the base case, 

reflecting the reduced pumping in well 14N/3E-14P1. The 

increased pumping in wells 14N/3E-13M1 and 14N/4E-18N1 

resulted in greater drawdown in parameter zone 2 and near 

14N/4E-18N1. The overall decline in simulated heads through 

2060 was similar to the base case; however, the monthly 

fluctuations in well 14N/4E-18N1 were larger than in the 

base case because, as shallow layers became dewatered, the 

pumpage was redistributed to deeper layers, which were less 

permeable. The difference in subsidence at the end of 2060 

between scenario 3 and the base case was small (less than 

0.07 ft) for all observation locations. 

Scenario 4 was similar to scenario 3, but with the added 

constraint that basin-wide pumpage was reduced by 3 percent 

per year during 2011–20; pumpage for 2020 was assumed to 

be constant during 2021–60. Total pumpage for scenario 4 

was about 13,200 acre-ft less than in the base case; simulated 

groundwater-storage depletion was about 12,700 acre-ft 

less than in the base case. The distribution and magnitude 

of simulated drawdown in layer 6 for scenario 4 was 

substantially different from the base case south of the South 

Coyote Canyon fault. North of the fault, the distribution of 

drawdown was similar to the base case, but the magnitude was 

substantially different. The drawdown near well 14N/4E-18N1 

was about 40 ft less than for the base case; near well 14N/4E14P1, drawdown was about 60 ft less than for the base case. 

The simulated hydraulic heads generally declined in the three 

production wells for scenario 4, however, the reduction in 

basin-wide pumpage helped to mitigate dewatering of the 

upper layers, and the seasonal fluctuations were smaller than 

in the base case. The simulated subsidence at the end of 2060 

ranged from about 0.12 to 0.43 ft less than in the base case.

Scenario 5 was the same as scenario 2, except that the 

pumpage for well 14N/3E-14P1 was reduced to zero. The 

total pumpage was about half the pumpage as that of the 

base case. Simulated groundwater-storage depletion was 

about 56 percent less than in the base case. The distribution 

and magnitude of simulated drawdown in model layer 6 for 

scenario 5 was substantially different from the base case. 

Simulated heads increased as much as 8 ft near well 14N/3E14P1 during 2011–60 compared with 100–135 ft of drawdown 

in the same area for the base case. In the eastern part of the 

basin near well 14N/4E-18N1, drawdown was as much as 

100 ft less than in the base case, indicating that pumping in 

well 14N/3E-14P1 substantially affected simulated heads in 

this area. Simulated heads generally declined through 2060, 

but the amount of decline in the three production wells was 

substantially less than in the base case. Subsidence continued 

for the projected period at all observation locations, but at a 

slower rate than in the base case. The simulated subsidence at 

the end of 2060 ranged from about 0.19 to 1.16 ft less than in 

the base case, indicating that the discontinuation of pumpage 

for well 14N/3E-14P1 would result in a substantial reduction 

of subsidence.

Overall, continued declines in the water table dewatered 

the more productive upper layers of the aquifer, causing more 

pumpage to be withdrawn from deeper, lower yielding layers 

and resulting in faster declines in the water table and greater 

vertical gradients in the future. Declines of the water table to 

the perforated intervals of wells could increase maintenance 

costs and alter the quality of water discharged from the wells. 

Water-management scenario 1 indicated that additional 

managed recharge resulted in a modest decrease (4–5 percent) 

in the rate of subsidence compared with historical conditions 

without managed recharge. The reduction of pumpage in 

the area of subsidence and redistribution of the amount of 

the reduction to wells in other parts of the basin (scenario 3) 

resulted in modest decreases (5–6 percent) in the rate of 

subsidence compared with the continuation of historical 

pumping levels. Including a basin-wide reduction of pumpage 

(cumulatively, a 24 percent decrease) along with targeted 

point-specific reduction and redistribution of pumpage 

(scenario 4), however, or discontinuing pumping in the area of 

greatest subsidence (scenario 5) demonstrated that subsidence 

could be reduced substantially (22–26 percent for scenario 4 

and 62–68 percent for scenario 5) compared with subsidence 

simulated for continuing historical pumping levels.
114 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

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Appendix 1 119

The U.S. Geological Survey (USGS) drilled 6 multiplewell monitoring sites containing 18 wells in Bicycle Basin. 

Lithologic logs were based on observations recorded during 

drilling and analysis of drill cuttings collected from the 

borehole following methods described by Kjos and others 

(2014) compiled for each well. 

Similar lithologic units, determined from the detailed 

lithologic logs (tables 1–1 to 1–6), were grouped to facilitate 

compilation of generalized lithologic columns (figs. 1–1 

through 1–6). Depths of contacts between lithologic units were 

determined using borehole geophysical logs. 

Appendix 1. Borehole Data for Selected Wells in Bicycle Basin at Fort Irwin 

National Training Center, California, 1993–2011

Table 1–1. Lithologic log from sieve samples for multiple-well monitoring site BLA2 (14N/3E-13M2–4), Bicycle Basin, Fort Irwin 

National Training Center, California.

[ft, feet]

Depth (ft) Description From To

0 20 No sample collected

20 40 Sand, fine to very loose and some gravel, granules to pebbles with rock fragments, poorly sorted; subrounded to subangular; 

moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2); some mica and mafic minerals.

40 60 Sand, fine to very coarse with granules, pebbles, and rock fragments; poorly sorted; subrounded to angular; moderate 

yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

60 80 Sand, very fine to coarse with occasional rock fragments, some silt; subrounded to subangular; poorly sorted; moderate 

yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

80 100 Sand, fine to very coarse with some granules and rock fragments; poorly sorted; subrounded (rock fragments are mostly 

angular); moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

100 130 Sand, very fine to very coarse with small pebbles, some rock fragments; poorly sorted; subrounded to subangular (rock 

fragments are angular); moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

130 140 Sand, very fine to coarse with silt and occasional rock fragments; poorly sorted; subrounded; olive gray (5 Y 3/2); abundance 

of mica and mafic minerals.

140 160 Silt with small amount of fine sand; occasional rock fragments; moderately well sorted; rock fragments are subrounded; light 

olive gray (5 Y 5/2); abundance of mafic minerals and mica.

160 180 Silt with small amount of very fine sand; occasional subrounded rock fragments; well sorted; olive gray (5 Y 3/2); abundance 

of mafic minerals and mica.

180 200 Ground-up rock fragments (mostly granitic) medium to very coarse grained, some fragments gravel-sized; grayish olive 

(10 Y 4/2).

200 220 Ground-up granitic rock, fine to medium ground; moderately well sorted; olive gray (5 Y 3/2); abundance of mafic minerals 

and mica.

220 240 Ground-up granitic rock, fine to coarse grained; moderately well sorted; occasional granule-size fragments; angular; olive 

gray (5 Y 3/2); abundance of mafic minerals and mica.

240 265 Ground-up granitic rock, fine to coarse, occasional granule size; poorly sorted; subangular to angular; olive gray (5 Y 3/2); 

abundance of mafic minerals and mica.

Appendix 1
120 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Table 1–2. Lithologic log from sieve samples for multiple-well monitoring site BA1 (14N/3E-22N1–2), Bicycle Basin, Fort Irwin National 

Training Center, California.

[ft, feet]

Depth (ft) Description From To

0 20 No sample collected

20 40 Sand, fine to very loose and some gravel, granules to pebbles with rock fragments, poorly sorted; subrounded to subangular; 

moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2); some mica and mafic minerals.

40 60 Sand, fine to very coarse with granules, pebbles, and rock fragments; poorly sorted; subrounded to angular; moderate 

yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

60 80 Sand, very fine to coarse with occasional rock fragments, some silt; subrounded to subangular; poorly sorted; moderate 

yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

80 100 Sand, fine to very coarse with some granules and rock fragments; poorly sorted; subrounded (rock fragments are mostly 

angular); moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

100 130 Sand, very fine to very coarse with small pebbles, some rock fragments; poorly sorted; subrounded to subangular (rock 

fragments are angular); moderate yellowish brown (10 YR 5/4) to dark yellowish brown (10 YR 4/2).

130 140 Sand, very fine to coarse with silt and occasional rock fragments; poorly sorted; subrounded; olive gray (5 Y 3/2); abundance 

of mica and mafic minerals.

140 160 Silt with small amount of fine sand; occasional rock fragments; moderately well sorted; rock fragments are subrounded; light 

olive gray (5 Y 5/2); abundance of mafic minerals and mica.

160 180 Silt with small amount of very fine sand; occasional subrounded rock fragments; well sorted; olive gray (5 Y 3/2); abundance 

of mafic minerals and mica.

180 200 Ground-up rock fragments (mostly granitic) medium to very coarse grained, some fragments gravel-sized; grayish olive 

(10 Y 4/2).

200 220 Ground-up granitic rock, fine to medium ground; moderately well sorted; olive gray (5 Y 3/2); abundance of mafic minerals 

and mica.

220 240 Ground-up granitic rock, fine to coarse grained; moderately well sorted; occasional granule-size fragments; angular; olive 

gray (5 Y 3/2); abundance of mafic minerals and mica.

240 265 Ground-up granitic rock, fine to coarse, occasional granule size; poorly sorted; subangular to angular; olive gray (5 Y 3/2); 

abundance of mafic minerals and mica.

Appendix 1
Appendix 1 121

Table 1–3A. Lithologic log from sieve samples for multiple well monitoring site BLA4 (14N/3E-23B1–3), Bicycle Basin, Fort Irwin 

National Training Center, California.

[Altitude of land surface, approximately 2,377 feet (ft). Drilled by U.S. Geological Survey December 8–12, 2007. Total depth drilled 865 ft. Screened 

intervals: 710–730, 440–460, 260–280 ft.]

Depth (ft) Description From To

0 20 Sand (S); very fine to medium sand; well sorted; subangular; brown (10YR 5/3).

20 40 Slightly gravelly sand ((g)S); fine to very coarse sand with granules to small pebbles; poorly sorted; subrounded to 

subangular; yellowish brown (10YR 5/4).

40 60 Slightly gravelly sand ((g)S); fine to very coarse sand with granules to small pebbles; poorly sorted; subrounded to 

subangular; yellowish brown (10YR 5/4).

60 80 Gravelly sand (gS); very fine to medium sand and granules to medium pebbles; poorly sorted; subrounded to subangular; 

yellowish brown (10YR 5/4).

80 100 Gravelly sand (gS); very fine to coarse sand and granules to small pebbles; poorly sorted; subangular; yellowish brown 

(10YR 5/4).

100 120 Sand (S); very fine to coarse sand; moderately to poorly sorted; subrounded; yellowish brown (10YR 5/4).

120 140 Gravelly sand (gS); very fine to very coarse sand and granules to small pebbles; poorly sorted; subrounded to subangular; 

yellowish brown (10YR 5/4).

140 160 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; rounded to subrounded; brown (10YR 5/3).

160 180 Clay (C); clay; very well sorted; brown (10YR 5/3).

180 200 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; rounded to subrounded; brown (10YR 5/3).

200 220 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; rounded to subrounded; brown (10YR 5/3).

220 240 Clayey sand (cS); very fine to coarse sand and clay; moderately to poorly sorted; rounded to subrounded; brown (10YR 5/3).

240 260 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

260 280 Gravelly sand (gS); fine to very coarse sand and granules to medium pebbles; poorly sorted; subrounded to subangular; dark 

yellowish brown (10YR 4/4).

280 300 Slightly gravelly clay ((g)M); clay with minor granules; poorly sorted; yellowish brown (10YR 5/4).

300 320 Sand (S); fine to coarse sand; well sorted; subrounded; yellowish brown (10YR 5/4).

320 340 Clayey sand (cS); fine to coarse sand and clay; moderately to poorly sorted; rounded to subrounded; yellowish brown 

(10YR 5/4).

340 360 Clayey silt (M); silt and clay; well sorted; yellowish brown (10YR 5/4).

360 380 Clayey silt (M); silt and clay; well sorted; yellowish brown (10YR 5/4).

380 400 Sandy clayey silt (sM); silt, clay and medium to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

400 420 Sandy clay (sC); clay with medium to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

420 440 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).

440 460 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).

460 480 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).

480 500 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).

500 520 Clayey silty sand (mS); very fine to medium sand and silt and clay; moderately sorted; rounded to subrounded; brown 

(10YR 5/3).

520 540 Slightly gravelly sand ((g)S); fine to coarse sand and minor granules; moderately to poorly sorted; subangular to subrounded; 

brown (10YR 5/3).

540 560 Silty sand (zS); very fine to coarse sand and silt; moderately to poorly sorted; subrounded; yellowish brown (10YR 5/4).

560 580 Gravelly sand (gS); fine to coarse sand and granules; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).
122 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Depth (ft) Description From To

580 600 Silty sand (zS); fine to coarse sand and silt; moderately to poorly sorted; subangular to subrounded; yellowish brown 

(10YR 5/4).

600 620 Sandy clay (sC); clay and fine to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

620 640 Sand (S); fine to medium sand; well sorted; subangular to subrounded; yellowish brown (10YR 5/4).

640 660 Sandy clay (sC); clay and fine to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

660 680 Sandy clay (sC); clay and fine to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

680 700 Sandy clay (sC); clay and fine to medium sand; well to moderately sorted; rounded to subrounded; brown (10YR 5/3).

700 720 Silty sand (zS); fine to coarse sand and silt; moderately to poorly sorted; subrounded to subangular; brown (10YR 5/3).

720 740 Gravelly silty sand (gmS); very fine to coarse sand and silt and granules; poorly sorted; subrounded to subangular; brown 

(10YR 5/3).

740 760 Gravelly silty sand (gmS); very fine to coarse sand and silt and granules; poorly sorted; subrounded to subangular; brown 

(10YR 5/3).

760 780 Gravelly silty sand (gmS); very fine to coarse sand and silt and granules; poorly sorted; subrounded to subangular; brown 

(10YR 5/3).

780 800 Silty sand (zS); very fine to coarse sand and silt; poorly sorted; subrounded; brown (10YR 5/3).

800 820 Sandy clay (sC); clay and fine to very coarse sand; poorly sorted; brown (10YR 5/3).

820 840 Sandy clay (sC); clay and very fine to fine sand; well sorted; brown (10YR 5/3).

840 860 Sandy clay (sC); clay and very fine to fine sand; well sorted; brown (10YR 5/3).

Table 1–3A. Lithologic log from sieve samples for multiple well monitoring site BLA4 (14N/3E-23B1–3), Bicycle Basin, Fort Irwin 

National Training Center, California.—Continued

[Altitude of land surface, approximately 2,377 feet (ft). Drilled by U.S. Geological Survey December 8–12, 2007. Total depth drilled 865 ft. Screened 

intervals: 710–730, 440–460, 260–280 ft.]

Table 1–3B. Lithologic log from shaker samples for multiple well monitoring site BLA4 (14N/3E-23B1–3), Bicycle Basin, Fort Irwin 

National Training Center, California.

[ft, feet]

Depth (ft) Description

10 Gravelly sand (gS); coarse to very coarse sand and granules; well sorted; subrounded to subangular; assorted colors.

20 Gravelly sand (gS); coarse to very coarse sand and granules; well sorted; subrounded to subangular; assorted colors.

30 Gravelly silty sand (gmS); coarse to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; assorted 

colors.

40 Gravelly silty sand (gmS); coarse to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; assorted 

colors.

50 Gravelly silty sand (gmS); coarse to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; assorted 

colors.

60 Gravelly silty sand (gmS); coarse to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; assorted 

colors.

70 Sandy gravel (sG); granules and very coarse sand; well sorted; subrounded to subangular; dark yellowish brown (10YR 4/4).

80 Gravelly sand (gS); very fine and very coarse sand and granules; well sorted; subrounded to subangular; light yellowish brown 

(10YR 6/4).

90 Gravelly sand (gS); very fine and very coarse sand and granules; well sorted; subrounded to subangular; light yellowish brown 

(10YR 6/4).

100 Gravelly silty sand (gmS); coarse to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; yellowish 

brown (10YR 5/4).

110 Sand (S); very fine to very coarse sand; poorly sorted; subrounded to subangular; light yellowish brown (10YR 6/4).

120 Gravelly clay (gM); clay with granules; well sorted; yellowish brown (10YR 5/4).
Appendix 1 123

Depth (ft) Description

130 Gravelly clayey sand (gmS); medium to very coarse sand, clay and granules; moderately sorted; subrounded to subangular; 

yellowish brown (10YR 5/4).

140 Gravelly silty sand (gmS); medium to very coarse sand, silt and granules to small pebbles; poorly sorted; subrounded to 

subangular; yellowish brown (10YR 5/4).

150 Silty sand (zS); very fine to coarse sand and silt; poorly sorted; subrounded to subangular; pale brown (10YR 6/3).

160 Sandy clay (sC); clay and very coarse sand; moderately sorted; yellowish brown (10YR 5/4).

170 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

180 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

190 Gravelly silty sand (gmS); very fine to coarse sand, silt and granules to medium pebbles; very poorly sorted; subrounded to 

subangular; yellowish brown (10YR 5/4) .

200 Sandy clay (sC); clay and coarse to very coarse sand; moderately sorted; yellowish brown (10YR 5/4).

210 Gravelly silty sand (gmS); medium to very coarse sand, silt and granules; moderately sorted; subrounded to subangular; 

yellowish brown (10YR 5/4).

220 Sandy clay (sC); clay and coarse to very coarse sand; moderately sorted; yellowish brown (10YR 5/4).

230 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

240 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

250 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

260 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

270 Silty sand (zS); very fine to very coarse sand and silt; very poorly sorted; subrounded to subangular; yellowish brown (10YR 

5/4).

280 Silty sand (zS); very fine to very coarse sand and silt; very poorly sorted; subrounded to subangular; yellowish brown (10YR 

5/4).

290 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

300 Sandy clay (sC); clay and coarse to very coarse sand; moderately sorted; yellowish brown (10YR 5/4).

310 Sandy clay (sC); clay and coarse to very coarse sand; moderately sorted; yellowish brown (10YR 5/4).

315

core shoe

Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

320 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

330 Gravelly silty sand (gmS); very fine to very coarse sand, silt and granules to small pebbles; very poorly sorted; subrounded to 

subangular; yellowish brown (10YR 5/4).

340 Gravelly clayey sand (gmS); coarse to very coarse sand, clay and granules to small pebbles; moderately to poorly sorted; 

subrounded to subangular; yellowish brown (10YR 5/4).

350 Gravelly clayey sand (gmS); coarse to very coarse sand, clay and granules to small pebbles; moderately to poorly sorted; 

subrounded to subangular; yellowish brown (10YR 5/4).

360 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

370 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

380 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

390 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

400 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

410 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

420 No sample collected.

430 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

440 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

450 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

460 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

Table 1–3B. Lithologic log from shaker samples for multiple well monitoring site BLA4 (14N/3E-23B1–3), Bicycle Basin, Fort Irwin 

National Training Center, California.—Continued

[ft, feet]
124 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Depth (ft) Description

470 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

480 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

490 Sandy silt (sZ); silt and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

500 Sandy silt (sZ); silt and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

510 Sandy silt (sZ); silt and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

520 Silt (Z); silt; very well sorted; yellowish brown (10YR 5/4).

530 Sandy silt (sZ); silt and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

540 Silty sand (zS); very fine sand to coarse sand and silt; poorly sorted; subrounded to subangular; yellowish brown (10YR 5/4).

550 Clay (C); clay; very well sorted; yellowish brown (10YR 5/4).

560 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

570 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

580 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

590 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

600 Sandy silt (sZ); silt and very fine to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

610 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

620 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

630 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

640 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

650 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

660

Core

Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

670 Silt (Z); silt; very well sorted; yellowish brown (10YR 5/4).

680 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

690 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

700 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

710 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

720 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

730 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

740 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

750 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

760 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

770 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

780 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

790 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

800 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

810 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

820 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

830 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

840 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

850 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

860 Sandy clay (sC); clay and coarse sand; moderately sorted; yellowish brown (10YR 5/4).

Table 1–3B. Lithologic log from shaker samples for multiple well monitoring site BLA4 (14N/3E-23B1–3), Bicycle Basin, Fort Irwin 

National Training Center, California.—Continued

[ft, feet]
Appendix 1 125

Table 1–4. Lithologic log from sieve samples for multiple-well monitoring site BLA3 (14N/3E-24Q1–5), Bicycle Basin, Fort Irwin National 

Training Center, California.

[ft, feet]

Depth (ft) Description From To

0 20 Sand, some gravel, some clay, sand is poorly sorted, very fine to very coarse, gravel size granule to medium pebble; angular 

to subrounded; yellowish brown (10 YR 5/4).

20 40 Sand, some gravel, sand is very fine to very coarse, gravel size granule to large pebble; poorly sorted; angular to subrounded; 

yellowish brown (10 YR 5/4).

40 60 Sand, minor gravel, sand is skewed towards fine; gravel size granule to medium pebble; well sorted; angular to subrounded; 

yellowish brown (10 YR 5/6).

60 80 Gravelly sand, sand is very fine to very coarse; gravel size granule to large pebble; very poorly sorted; angular to subrounded; 

yellowish brown (10 YR 5/6).

80 100 Sand, minor gravel, trace clay, trace silt, sand is very fine to very coarse; gravel size granule to large pebble; poorly sorted; 

skewed towards fine angular to subrounded; yellowish brown (10 YR 5/4).

100 120 Gravelly sand, very fine to very coarse; granules to large cobbles; poorly sorted; angular to subrounded; yellowish brown 

(10 YR 5/6).

120 140 Sand granules, some clay, some gravel, very fine to very coarse sand; granules to large pebbles; poorly sorted; angular to 

subrounded; yellowish brown (10 YR 5/6).

140 160 Clayey sand, some gravel, very fine to very coarse; granules to large cobbles; poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).

160 180 Sandy gravel, granules to large cobbles, very fine to very coarse; poorly sorted; angular to subrounded; yellowish brown 

(10 YR 5/6).

180 200 Clayey sandy gravel, granules to large cobbles, very fine to very coarse; very poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).

200 220 Gravelly sand, some clay, granules to boulders, very fine to coarse sand; poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).

220 240 Gravelly sand, minor clay, granules to boulders, very fine to very coarse sand; moderately sorted; angular to subrounded; 

yellowish brown (10 YR 5/6).

240 260 Gravelly sand, some clay, very fine to very coarse; granules to cobbles; poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/4).

260 280 Gravelly sand, trace clay, very fine to very coarse; granules to cobbles; poorly sorted; angular to subrounded; yellowish brown 

(10 YR 5/6).

280 300 Gravelly sand, minor clay, very fine to very coarse sand; granules to cobbles; moderately sorted; angular to subrounded; 

yellowish brown (10 YR 5/6).

300 320 Gravelly sand, very fine to very coarse; granules to large pebbles; angular rock chips; moderately sorted; angular to 

subrounded; yellowish brown (10 YR 5/6).

320 340 Sand, some gravel, very fine to very coarse sand; granules to angular rock chips indicating broken pebbles and cobbles; 

poorly sorted; angular to subrounded; yellowish brown (10 YR 5/6).

340 360 Sand, some gravel, minor clay, very fine to very coarse; granules to pebbles; poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/4).

360 380 Sand, some gravel, very fine to very coarse; granules to small cobbles; moderately sorted; angular to subrounded; light 

yellowish brown (10 YR 6/4).

380 400 Gravelly sand, some clay, some silt, trace clay, very fine to very coarse; granules to cobbles; moderately sorted; angular chips 

from bit action to subrounded sand grains; light yellowish brown (10 YR 6/4).

400 420 Gravelly sand, very fine to very coarse; granules to cobbles; moderately sorted; skewed towards coarse; angular to 

subrounded; yellowish brown (10 YR 5/6).

420 440 Sand, some clay, some gravel, very fine to very coarse; granules to cobbles; moderately sorted; skewed towards fine; angular 

to subrounded; yellowish brown (10 YR 5/4).

440 460 Gravelly sand, minor clay, very fine to very coarse; granules to large cobbles; poorly sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).
126 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Depth (ft) Description From To

460 480 Gravelly sand, minor gravel, fine to very coarse; granules to large cobbles; well sorted; angular to rounded; yellowish brown 

(10 YR 5/6).

480 500 Clayey sand, some gravel, very fine to very coarse; granules to large cobbles; well sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).

500 520 Silty sand, some clay, minor gravel, very fine to very coarse; granules; very well sorted; angular to subrounded; yellowish 

brown (10 YR 5/6).

520 540 Sand, very fine to very coarse; moderately sorted; angular to subrounded; yellowish brown (10 YR 5/6).

540 560 Sand, very fine to very coarse; poorly sorted; angular to subrounded; yellowish brown (10 YR 5/6).

560 580 Clayey sand, trace gravel, granules very fine to very coarse; well sorted; angular to subrounded; yellowish brown (10 YR 5/6).

580 600 Sand, some clay, some gravel, very fine to very coarse, granules to small cobbles; poorly sorted; angular to subrounded; 

yellowish brown (10 YR 5/6).

600 620 Clayey sand, very fine to very coarse; well sorted; angular to subrounded; yellowish brown (10 YR 4/2).

620 640 Sand, some silt, very fine to very coarse; moderately sorted; angular to subrounded; yellowish brown (10 YR 5/6).

640 660 Sand, very fine to very coarse; well sorted; angular to subrounded; yellowish brown (10 YR 5/6).

660 680 Sand, very fine to very coarse; moderately sorted, skewed toward medium; angular to subrounded; yellowish brown (10 YR 

5/6).

680 700 Sand, minor clay, very fine to very coarse; poorly sorted; angular to subrounded; yellowish brown (10 YR 5/6).

700 720 Gravelly sand, very fine to very coarse; poorly sorted; angular to subrounded; yellowish brown (10 YR 5/6).

720 740 Gravelly sand, very fine to very coarse, granules to boulders; poorly sorted; angular to subrounded; pale brown (10 YR 6/3).

740 760 Gravelly sand, very fine to very coarse, granules to boulders; moderately sorted; skewed toward coarse; light olive gray 

(5 Y 5/2).

760 780 Gravelly sand, very fine to very coarse sand, granules to cobbles, increase in sand content; moderately sorted; angular to 

subrounded; light brown (5 YR 5/6).

780 800 Gravelly sand, very fine to very coarse, granules to boulders; poorly sorted; angular to subrounded; pale brown (10 YR 6/3).

800 820 Gravelly sand, very fine to very coarse sand, granules to cobbles; moderately sorted, skewed; angular to subrounded; light 

yellowish brown (10 YR 6/4).

820 840 Gravelly sand, very fine to very coarse, granules to cobbles; poorly sorted; angular to subrounded; light yellowish brown 

(10 YR 6/4).

840 860 Gravelly sand, very fine to very coarse, granules to cobbles; poorly sorted; angular to subrounded; light yellowish brown 

(10 YR 6/4).

860 880 Gravelly sand, very fine to very coarse, granules to boulders; poorly sorted; angular to subrounded; light yellowish brown 

(10 YR 6/4).

880 900 Gravelly sand, very fine to very coarse, granules to boulders; poorly sorted; angular to subrounded; light yellowish brown 

(10 YR 6/4).

Table 1–4. Lithologic log from sieve samples for multiple-well monitoring site BLA3 (14N/3E-24Q1–5), Bicycle Basin, Fort Irwin National 

Training Center, California.—Continued

[ft, feet]
Appendix 1 127

Table 1–5A. Lithologic log from sieve samples and for multiple-well monitoring site BLA5 (14N/3E-26K1–4), Bicycle Basin, Fort Irwin 

National Training Center, California.

[Previously published in Kjos and others, 2014. Altitude of land surface, approximately 2,345 feet (ft). Drilled by U.S. Geological Survey using mud-rotary 

drilling method, March 19, 2011. Total depth drilled, 370 ft. Screened intervals, 320–340, 190–210, and 190–210 ft. Washed—sample was washed to remove 

fine grained material and drilling mud.]

Depth 

(ft) Description

5

1C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

10

2C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 4/4); calcareous.

15

3C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

20

4C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

25

5C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

26.5

6C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

30

7C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

35

8C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4); calcareous.

40

9C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 4/4); calcareous.

45

10C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; brown (7.5YR 5/4).

50

11C shoe

Clay (C); clay with trace very fine to fine sand; well sorted; yellowish brown (10YR 5/4); extremely calcareous.

55

12C shoe

Sandy silt (sZ); silt with very fine to fine sand; well sorted; brown (7.5YR 5/4); slightly calcareous.

60

13C shoe

Silt (Z); silt with trace very fine to fine sand and trace large pebbles; moderately to well sorted; brown (7.5Y 5/4); calcareous.

70 Sandy clayey silt (sM); silt with clay, very fine to medium sand, and trace granules; moderately sorted; yellowish brown 

(10YR 5/4); calcareous.

80 Clay (C); clay with trace very fine to fine sand; well sorted; yellowish brown (10YR 5/6); calcareous.

90 Clay (C); clay with trace very fine to fine sand; well sorted; dark yellowish brown (10YR 4/4).

100 Clay (C); clay with trace very fine to fine sand; well sorted; yellowish brown (10YR 5/4).

110 Clay (C); clay with trace very fine to medium sand; well sorted; yellowish brown (10YR 5/4); calcareous.

120 Clay (C); clay with trace very fine to medium sand; well sorted; yellowish brown (10YR 5/4); calcareous.

130 Clay (C); clay with trace very fine to medium sand; well sorted; brown (7.5YR 4/4); slightly calcareous.

140 Silty clay (M); clay with silt and trace very fine to medium sand; moderately to well sorted; brown (7.5YR 4/4).

150 Clayey sandy silt (sM); silt with very fine to medium sand and clay; moderately sorted; yellowish brown (10YR 5/4); calcareous.

160 Clay (C); clay with trace very fine to fine sand; well sorted; yellowish brown (10YR 5/4).

170 Gravelly clayey silty sand (gmS); medium to very coarse sand with silt, clay, and granules; poorly sorted; angular to subangular; 

dark yellowish brown (10YR 4/4); slightly calcareous.

180 Gravelly clayey silty sand (gmS); medium to very coarse sand with silt, clay, and granules to small pebbles; very poorly sorted; 

angular to subangular; dark yellowish brown (10YR 4/4).

190 Gravelly clayey silty sand (gmS); medium to very coarse sand with silt, clay, and granules; very poorly sorted; angular to 

subangular; yellowish brown (10YR 5/4).
128 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Depth 

(ft) Description

200 Sandy silty clay (sM); clay with silt and fine sand with trace coarse sand; moderately sorted; dark yellowish brown (10YR 4/4); 

slightly calcareous.

210 Sandy silty clay (sM); clay with silt and fine to coarse sand; moderately to poorly sorted; yellowish brown (10YR 5/4).

220 Gravelly clayey silty sand (gmS); medium to very coarse sand with silt, clay, and granules with trace small to medium pebbles; 

very poorly sorted; angular to subangular; yellowish brown (10YR 5/4).

230 Silty sandy gravel (msG); granules to medium pebbles with coarse to very coarse sand and silt; moderately to poorly sorted; 

angular to subangular; dark yellowish brown (10YR 4/4); slightly calcareous.

240 Silty sandy gravel (msG); granules to medium pebbles with silt and coarse to very coarse sand; moderately to poorly sorted; 

angular to subangular; dark yellowish brown (10YR 4/4); slightly calcareous.

250 Silty sandy gravel (msG); granules to medium pebbles with coarse to very coarse sand and silt; moderately to poorly sorted; 

angular to subangular; dark yellowish brown (10YR 4/4); slightly micaceous.

260 Silty clayey gravelly sand (gmS); medium to very coarse sand with granules to small pebbles, clay and silt; very poorly sorted; 

angular to subangular; brown (10YR 4/3).

270 Clayey gravelly sand (gmS); medium to very coarse sand with granules to small pebbles and clay; moderately to poorly sorted; 

angular to subangular; light olive brown (2.5Y 5/3); calcareous.

280 Silty clayey gravelly sand (gmS); medium to very coarse sand with granules, clay, and silt; very poorly sorted; angular to 

subangular; olive (5Y 4/3); slightly calcareous.

290 Silty clayey gravelly sand (gmS); medium to very coarse sand with granules, clay, and silt; very poorly sorted; angular to 

subangular; olive (5Y 4/3); slightly calcareous.

300 Sandy gravelly clayey silt (gM); silt with clay, granules, medium to very coarse sand, and trace small pebbles; very poorly 

sorted; light olive brown (2.5Y 5/4); calcareous; slightly micaceous.

310 Silty gravelly clayey sand (gmS); medium to very coarse sand with clay, granules, and silt; very poorly sorted; angular to 

subangular; light olive brown (2.5Y 5/4); slightly calcareous; slightly micaceous.

310

Washed

Gravelly sand (gS); coarse to very coarse sand with granules to small pebbles; well to moderately sorted; very angular to 

angular; yellowish brown (10YR 5/4); abundant microcrystalline quartz.

320 Sandy clayey silt (sM); silt with clay and medium to very coarse sand; poorly sorted; olive (5Y 5/3); slightly calcareous.

330 Silty clayey sand (mS); medium to very coarse sand with silt, clay, and trace granules to small pebbles; poorly sorted; angular to 

subangular; olive (5Y 4/3).

340 Silty gravelly sand (gmS); medium to very coarse sand with granules to small pebbles and silt; poorly sorted; angular to 

subangular; olive brown (2.5Y 4/3); slightly micaceous.

350 Silty gravelly sand (gmS); medium to very coarse sand with granules to small pebbles and silt; poorly sorted; angular to 

subrounded; olive brown (2.5Y 4/4); micaceous.

360 gravelly sand (gmS); coarse to very coarse sand with granules to small pebbles and silt; poorly sorted; angular to subangular; 

olive brown (2.5Y 4/4); calcareous; micaceous.

370 Gravelly sand (gS); coarse to very coarse sand with granules to small pebbles and trace silt; moderately to poorly sorted; angular 

to subangular; light olive brown (2.5Y 5/3); abundant quartz.

370

Washed

Gravelly sand (gS); coarse to very coarse sand with granules to small pebbles; well to moderately sorted; very angular to 

subangular; yellowish brown (10YR 5/4); slightly calcareous; abundant microcrystalline quartz.

Table 1–5A. Lithologic log from sieve samples and for multiple-well monitoring site BLA5 (14N/3E-26K1–4), Bicycle Basin, Fort Irwin 

National Training Center, California.—Continued

[Previously published in Kjos and others, 2014. Altitude of land surface, approximately 2,345 feet (ft). Drilled by U.S. Geological Survey using mud-rotary 

drilling method, March 19, 2011. Total depth drilled, 370 ft. Screened intervals, 320–340, 190–210, and 190–210 ft. Washed—sample was washed to remove 

fine grained material and drilling mud.]
Appendix 1 129

Table 1–5B. Lithologic log from shaker samples for multiple-well monitoring site BLA5 (14N/3E-26K1–4), Bicycle Basin, Fort Irwin 

National Training Center, California.

[Previously published in Kjos and others, 2014. Altitude of land surface, approximately 2,345 feet (ft). Drilled by U.S. Geological Survey using mud-rotary 

drilling method, March 19, 2011. Total depth drilled, 370 ft. Screened intervals, 320–340, 190–210, and 190–210 ft.]

Depth (ft) Description From To

0 60 No sample collected; cored interval.

60 80 Clay (C); clay with trace very fine to medium sand; well to moderately sorted; brown (7.5YR 5/4); calcareous.

80 100 Clay (C); clay with trace very fine to medium sand; well to moderately sorted; brown (7.5YR 5/3); calcareous.

100 120 Clay (C); clay with trace very fine to medium sand; well to moderately sorted; brown (7.5YR 5/3); slightly calcareous.

120 140 Clay (C); clay with trace very fine to medium sand; well to moderately sorted; brown (7.5YR 5/4); slightly calcareous.

140 160 Clay (C); clay with trace very fine to medium sand; well to moderately sorted; brown (7.5YR 5/3); calcareous.

160 180 Silty sand (zS); very fine to medium sand with silt; well to moderately sorted; angular to subangular; dark yellowish brown 

(10YR 4/4); calcareous.

180 200 Slightly gravelly silty sand ((g)mS); fine to coarse sand with silt and granules to small pebbles; poorly sorted; angular to 

subangular; dark yellowish brown (10YR 4/4); slightly calcareous.

200 220 Clayey silty sand (mS); fine to coarse sand with silt and clay; moderately to poorly sorted; angular to subangular; dark 

yellowish brown (10YR 4/4); slightly calcareous.

220 240 Silty sand (zS); fine to coarse sand with silt; well to moderately sorted; angular to subangular; brown (10YR 4/3); slightly 

calcareous.

240 260 Slightly gravelly silty sand ((g)mS); medium to very coarse sand with silt and granules to small pebbles; moderately to poorly 

sorted; subangular to subrounded; brown (10YR 4/3); calcareous.

260 280 Sand (S); medium to very coarse sand with trace granules, silt and trace fine sand; moderately to poorly sorted; subangular to 

subrounded; dark grayish brown (2.5Y 4/2); slightly calcareous; micaceous.

280 300 Silty sand (zS); medium to very coarse sand with silt, trace granules and trace fine sand; poorly sorted; subangular to 

subrounded; very dark grayish brown (2.5Y 3/2); micaceous.

300 320 Silty sand (zS); fine to coarse sand with silt and trace granules to small pebbles; moderately to poorly sorted; subangular to 

subrounded; very dark grayish brown (2.5Y 3/2); micaceous.

320 340 Silty sand (zS); fine to coarse sand with silt and trace very coarse sand; moderately to poorly sorted; subangular to 

subrounded; very dark grayish brown (2.5Y 3/2); calcareous; micaceous.

340 360 Slightly gravelly silty sand ((g)mS); medium to very coarse sand with silt and granules to medium pebbles; moderately to 

poorly sorted; angular to subangular; olive brown (2.5Y 4/3); calcareous; micaceous.

360 370 Slightly gravelly silty sand ((g)mS); medium to very coarse sand with silt and granules to small pebbles; moderately to poorly 

sorted; angular to subangular; olive brown (2.5Y 4/3).
130 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Table 1–6. Lithologic log of sieve samples log for multiple-well monitoring site BLA1 (14N/3E-35C2–3), Bicycle Basin, Fort Irwin 

National Training Center, California.

[ft, feet]

Depth (ft) Description From To

0 20 Sand, fine to coarse with granules and pebbles; poorly sorted; subangular to subrounded; moderate yellowish brown 

(10 YR 5/4).

20 40 Gravel, granules to pebbles with sand, fine to coarse; poorly sorted; angular to subrounded; moderate yellowish brown 

(10 YR 5/4).

40 60 Sand, fine to coarse with granules and pebbles; poorly sorted; subrounded ; mafic minerals, mica; dark yellowish brown 

(10 YR 4/2).

60 105 Gravel, granules to pebbles, with sand, fine to coarse; pootly sorted; angular to subrounded; mafic minerals; dark yellowish 

brown (10 YR 4/2).

105 120 Clay with sand, fine and medium; abundant mica; olive gray (5 Y 3/2).

120 140 Clay with fine sand, granules and pebbles; abundant mica; olive gray (5 Y 3/2).

140 175 Clay with sand, fine to medium, granules, and pebbles; abundant mica; olive gray (5 Y 3/2).

175 198 Fractured granitic bedrock, angular fragments; biotite, hornblend, feldspar, quartz.

198 200 Diorite with calcified fracture.
Appendix 1 131

Figure 1–1. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BLA2 (14N/3E-13M2–4), drilled in Bicycle Basin, Fort Irwin National Training Center, California.

Sand

Clay

Gravelly sand

Gravelly sand

Gravelly sand

Gravelly sand

Slightly clayey

gravelly sand

Slightly clayey

gravelly sand

Sandy gravel

Gravelly sand

Gravelly sand

Sand

100

200

300

400

500

600

0

sac11-0424_Figure A01 Well const 14N/03E-13M2-4 (BLA2)

100

0

200

300

400

500

600

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts

per second

0 10050 50

Resistivity,

in ohm-meters

(16N-short normal,

64N-long normal)

0 100

Resistivity

in ohm-meters

(electromagnetic

induction tool)

Spontaneous

potential,

in millivolts

Depth, in feet below land surface

SAND SAND

GROUT GROUT

BLA2-1 (13M2)

BLA2-3 (13M4)BLA2-2 (13M3)

64-N

16-N

Summary

lithology

Stratigraphy

Well construction

and water level

(measured Feb. 13, 2012)

Qya

Qoa

QToa

3

Tyg

QToa

2

QToa

1

2,400

2,300

2,200

2,100

2,000

1,900

Altitude, in feet above North American Vertical Datum of 1988

Model

layers

1

2

3

4

5

6

7

Geologic unit/age

Younger alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

Younger alluvial gravels/Tertiary

Qya

Qoa Older alluvium/Quaternary

Tyg

QToa 3

QToa 1

QToa 2

EXPLANATION
132 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Sand

Gravelly sand

Gravelly sand

Gravelly sand

Gravelly sand

Gravelly silty

sand

Slightly gravelly

sand

100

200

300

0

sac11-0424_Figure A02 Well const BA1

No data

100

0

200

300

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts

per second

0 10050 50

Resistivity,

in ohm-meters

(16N-short normal,

64N-long normal)

0 100

Spontaneous

potential,

in millivolts

Depth, in feet below land surface

SAND SAND

GROUT

BA-1 (22N-1)

BA-1 (22N-2)

64-N

16-N

Summary

lithology

Well construction

and water level

(measured Mar. 30, 2000)

Resistivity,

in ohm-meters

(electromagnetic

induction tool)

Dry

Stratigraphy

Qya

Qoa

QToa

2,400

2,300

2,200

Altitude, in feet above 

North American Vertical Datum of 1988

Bc

Geologic unit/age

Younger alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

 Basement complex

Qya

Qoa Older alluvium/Quaternary

QToa

Bc

EXPLANATION

Figure 1–2. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BA1 (14N/3E-22N1–2), drilled in Bicycle Basin, Fort Irwin National Training Center, California.
Appendix 1 133

Sand

Gravelly sand

Gravelly sand

Gravelly sand

Clayey

sandy silt

Clayey sandy

 silt

Clayey sandy

 silt

Clayey sandy

 silt

Ash

Sandy clayey

 silt

Slightly silty

 clay

Silty sand

Sandy clayey

 silt

Silty sand

100

200

300

400

500

600

700

800

900

0

sac11-0424_Figure A03 Well const BLA4

Sandy clay

No data

2,300

2,200

2,100

2,000

1,900

1,800

1,700

1,600

1,500

Altitude, in feet above North American Vertical Datum of 1988

100

0

200

300

400

500

600

700

800

900

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts

per seconds

0 10050 50

Resistivity,

in ohm-meters

(16N-short normal,

64N-long normal)

0 100

Resistivity,

in ohm-meters

(electromagnetic

induction tool)

Spontaneous

potential,

in millivolts

Depth, in feet below land surface 

SAND SAND SAND

GROUT

GROUT

GROUT

GROUT

BLA4-1 (23B1)

BLA4-3 (23B3)BLA4-2 (23B2)

64-N

16-N

Summary

lithography

Well construction and water

level (measured Feb. 13, 2012)

Sampled cored interval and vertical 

 hydraulic conductivity, in feet per day

Stratigraphy

0.0009

0.01

0.0004

Qya

Qoa

QToa

3

QTol

2

Tyg

Tog

1

2

3

4

5

6

7

8

QToa

1

QToa

2

Model

layers

Geologic unit/age

Younger alluvium/Quaternary Older alluvium/

Quaternary-Tertiary

Older clay lacustrine/

Quaternary-Tertiary

Qya

Qoa Older alluvium/Quaternary Tog Older alluvial gravels/Tertiary

QToa 3 Tyg Younger alluvial gravels/Tertiary

QToa 1

QToa 2

EXPLANATION

QTol

Figure 1–3. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BLA4 (14N/3E-23B1–3), drilled in Bicycle Basin, Fort Irwin National Training Center, California.
134 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Sand

Sandy gravel

Gravelly sand

Gravelly sand

Gravelly sand

Clayey sand

Slightly gravelly

 sand

Silty sandy

 gravel

Gravelly sand

Gravelly sand

 (mafic, granitic)

Sand

Slightly gravelly 

 sand

Consolidated 

 sand

Sandstone

100

200

300

400

500

600

700

800

900

0

sac11-0424_Figure A04 Well const BLA3

1,700

1,800

1,900

2,000

2,100

2,200

2,300

Altitude, in feet above North American Vertical Datum of 1988

1,500

1,600

100

0

200

300

400

500

600

700

800

900

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts 

per second

0 10050 50

Resistivity,

in ohm-meters

(16N-short normal,

64N-long normal)

0 100

Resistivity,

in ohm-meters

(electromagnetic

conductivity tool) 

Spontaneous

potential,

in millivolts

Depth, in feet below land surface

SAND SAND SAND

SAND

SAND

GROUT

GROUT GROUT

GROUT

BLA3-1 (24Q1)

BLA3-3 (24Q3)

BLA3-5 (SWN 24Q5)

BLA3-2 (24Q2)

BLA3-4 (24Q4)

64-N

16-N

Summary

lithology

Well construction

and water level

(measured Feb. 13, 2012) Stratigraphy

Qya

Qoa

QToa

3

Tyg

Tog

Model

layers

QToa

2

QToa

1

1

2

3

4

5

6

7

8

Geologic unit/age

Younger alluvium/Quaternary Older alluvium/

Quaternary-Tertiary

Qya

Qoa Older alluvium/Quaternary Tog Older alluvial gravels/Tertiary

QToa 3 Tyg Younger alluvial gravels/Tertiary

QToa 1

QToa 2

EXPLANATION

Figure 1–4. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BLA3 (14N/3E-24Q1–5), drilled in Bicycle Basin, Fort Irwin National Training Center, California.
Appendix 1 135

Sandy gravel

Ash

Sandy gravel

Sandy gravel

Silty sandy

 gravel

Silty clay

Silty clay

Silty clay

Clay

Silty sandy

 gravel

Sandy gravel

Sandy gravel

Sandy gravel

Sandy gravel

Clay

100

200

300

400

0

sac11-0424_Figure A05 Well const BLA5&5B

No data

100

0

200

300

400

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts

per second

0 10050 50

Resistivity,

in ohm-meters

(16N-short

normal, 64Nlong normal)

0 100

Resistivity,

in ohm-meters

(electromagnetic

induction tool)

Spontaneous

potential,

in millivolts

Depth, in feet below land surface

2500 500

Delta time, in

microseconds

per foot

SAND

SAND

GROUTGROUT

BLA5-1 (26K1)

BLA5-3 (26K3)

BLA5-2 (26K2, Destroyed)

BLA5B (26K4)

64-N

16-N

Summary

lithology

Sampled cored interval and vertical 

 hydraulic conductivity, in feet per day

0.013

Stratigraphy

Well construction and water 

level (measured Mar. 27, 2012)

Model

layers

Geologic unit/age

Playa/Quaternary

Older clay lacustrine/Quaternary-Tertiary

Older alluvium/Quaternary-Tertiary

Basement complex - weathered bedrock

Qp

QTol 3

QToa 2

Bc

1

2

2,300

2,200

2,100

2,000

Altitude, in feet above North American Vertical Datum of 1988

QToa

2

Bc

QTol

3

Qp

Tyg Younger alluvial gravels/Tertiary

Tyg 3

EXPLANATION

Figure 1–5. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BLA5 (14N/3E-26K1–4), drilled in Bicycle Basin, Fort Irwin National Training Center, California (modified from 

Kjos and others, 2014).

Geophysical logs were made at each borehole 

immediately after completion of drilling using methods 

described by Kjos and others (2014). The logs of the uncased 

boreholes, which were filled with drilling mud, included 

16- and 64-inch normal resistivity, lateral (6-foot) or, for 

newer wells, electromagnetic (EM) induction resistivity, 

spontaneous potential (SP), natural gamma, and caliper logs 

(figs. 1–1 through 1–6). These logs provide information 

about the character of the formations and the presence and 

quality of groundwater. Data from the geophysical logs were 

used in conjunction with the lithologic logs to determine the 

placement of piezometers in multiple-well monitoring sites. 

Additionally, these data from wells, in conjunction with waterquality data, were used to estimate the depths of contacts 

between stratigraphic units on the basis of the depth at which 

there are shifts in the geophysical logs as summarized here.

Resistivity devices measure the evident resistivity of 

a volume of rock under the direct application of an electric 

current (Keys and MacCary, 1971). Resistivity logs are used 

to determine formation resistivity. Resistivity generally is 

correlated to grain size. Low resistivity generally indicates the 

presence of fine-grained deposits, such as silt, fine sand, and 

shale; high resistivity indicates the presence of coarse-grained 

materials, such as coarse sand and gravel.

The SP devices measure voltage differences between 

the borehole fluid and the surrounding rock (Keys and 

MacCary, 1971). The SP logs mainly are used for correlating 

geologic units, determining bed thickness, and differentiating 

nonporous and porous beds. The SP logs generally have a 

baseline corresponding to impermeable beds, such as clay or 

shale. Where formation water is less resistive than the drilling 

mud (more saline), deflections to the left of the baseline 

correspond to permeable strata; the opposite is true where 

formation water is more resistive than the drilling mud.

Appendix 1
136 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Natural gamma logs measure the intensities of gammaray emissions resulting from the natural decay of potassium-40 

and of the daughter products of uranium and thorium. Gamma 

logs primarily are used as indicators of lithology and for 

geologic correlation. Higher intensity gamma rays generally 

are emitted by clay and feldspar-rich gravel and granite 

(Driscoll, 1986). At Fort Irwin, an increase in gamma intensity 

generally is interpreted as corresponding to an increase in 

granitic materials in the deposits.

References Cited

Driscoll, F.G., 1986, Groundwater and wells: St. Paul, Minn., 

Johnson Division, p. 168–200.

Gravelly sand

Sandy gravel

(granitic bedrock)

Silt

Silty sand

100

200

0

sac11-0424_Figure A06 Well const BLA1

Qya

Qoa

QToa

Bc

2,300

2,200

Altitude, in feet above 

North American Vertical Datum of 1988

100

0

200

0 2010

Caliper,

in inches

0 200100 0 60

Natural

gamma,

in counts

per second

0 10050 50

Resistivity,

in ohm-meters

(16N-short normal,

64N-long normal)

0 100

Spontaneous

potential,

in millivolts

Depth, in feet below land surface

SAND SAND GROUT

BLA1-1 (35C2) 

BLA1-2 (35C3)

64N

16N

Summary

lithology

Well construction

and water level

(measured Feb. 13, 2012)

Resistivity,

in ohm-meters

(electromagnetic

induction tool)

Dry

Dry

Stratigraphy

Geologic unit/age

Younger alluvium/Quaternary

Older alluvium/Quaternary-Tertiary

Qya

Qoa Older alluvium/Quaternary

QToa

Bc Basement complex-weathered rock

Figure 1–6. Stratigraphic columnar sections showing a geophysical log, well-construction diagram, and stratigraphic column for 

borehole of monitoring site BLA1 (14N/3E-35C2–3), drilled in Bicycle Basin, Fort Irwin National Training Center, California.

Keys, W.S., and MacCary, L.M., 1971, Application of 

borehole geophysics to water-resources investigations: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations Report, book 2, chap. E1, 126 p., 

https://pubs.er.usgs.gov/publication/twri02E1.

Kjos, A.R., Densmore, J.N., Nawikas, J.M., and Brown, A.A., 

2014, Construction, water-level, and water-quality data 

for multiple-well monitoring sites and test wells, Fort 

Irwin National Training Center, San Bernardino County, 

California, 2009–12: U.S. Geological Survey Data 

Series 788, 139 p., https://doi.org/10.3133/ds788.
Appendix 2 137

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: B-1

351830116364501 14N/3E-13K1S 02/01/1955 2,226.80 170.90 2,397.7

351830116364501 14N/3E-13K1S 05/01/1963 2,222.70 175.00 2,397.7

351830116364501 14N/3E-13K1S 05/01/1965 2,225.70 172.00 2,397.7

351830116364501 14N/3E-13K1S 06/14/1965 2,224.70 173.00 2,397.7

351830116364501 14N/3E-13K1S 06/01/1967 2,218.70 179.00 2,397.7

351830116364501 14N/3E-13K1S 01/01/1968 2,221.70 176.00 2,397.7

351830116364501 14N/3E-13K1S 01/01/1969 2,216.70 181.00 2,397.7

351830116364501 14N/3E-13K1S 02/01/1970 2,216.70 181.00 2,397.7

351830116364501 14N/3E-13K1S 03/01/1973 2,208.70 189.00 2,397.7

351830116364501 14N/3E-13K1S 06/01/1974 2,216.70 181.00 2,397.7

351830116364501 14N/3E-13K1S 07/13/1978 2,213.70 184.00 2,397.7

351830116364501 14N/3E-13K1S 12/01/1978 2,212.70 185.00 2,397.7

351830116364501 14N/3E-13K1S 04/10/1979 2,211.30 186.39 2,397.7

351830116364501 14N/3E-13K1S 07/29/1980 2,209.90 187.83 2,397.7

351830116364501 14N/3E-13K1S 01/20/1981 2,210.40 187.25 2,397.7

351830116364501 14N/3E-13K1S 06/24/1982 2,200.80 196.89 2,397.7

351830116364501 14N/3E-13K1S 11/16/1982 2,204.90 192.83 2,397.7

351830116364501 14N/3E-13K1S 11/15/1983 2,203.60 194.14 2,397.7

351830116364501 14N/3E-13K1S 01/26/1993 2,188.00 209.69 2,397.7

351830116364501 14N/3E-13K1S 07/21/1994 2,176.90 220.80 2,397.7

351830116364501 14N/3E-13K1S 11/22/1994 2,185.80 211.87 2,397.7

351830116364501 14N/3E-13K1S 03/30/2000 2,171.00 226.72 2,397.7

351830116364501 14N/3E-13K1S 03/02/2005 2,131.60 266.12 2,397.7

Local ID: B-4

351829116371201 14N/3E-13M1S 06/30/1965 2,215.80 203.00 2,418.8

351829116371201 14N/3E-13M1S 04/01/1967 2,196.80 222.00 2,418.8

351829116371201 14N/3E-13M1S 01/01/1968 2,194.80 224.00 2,418.8

351829116371201 14N/3E-13M1S 01/01/1969 2,187.80 231.00 2,418.8

351829116371201 14N/3E-13M1S 03/01/1970 2,179.80 239.00 2,418.8

351829116371201 14N/3E-13M1S 05/01/1974 2,193.80 225.00 2,418.8

351829116371201 14N/3E-13M1S 12/01/1978 2,170.80 248.00 2,418.8

351829116371201 14N/3E-13M1S 01/01/1981 2,160.80 258.00 2,418.8

351829116371201 14N/3E-13M1S 09/07/1997 2,116.10 302.69 2,418.8

351829116371201 14N/3E-13M1S 07/28/2000 2,123.80 295.01 2,418.8

351829116371201 14N/3E-13M1S 03/01/2005 2,123.30 295.46 2,418.8

Appendix 2. Water-Level Data for Selected Wells in Bicycle Basin, Fort Irwin 

National Training Center, California, 1955–2015

Appendix 2
138 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA2-1

351829116371201 14N/3E-13M1S 11/06/2007 2,130.10 288.73 2,418.8

351829116371201 14N/3E-13M1S 02/14/2008 2,130.60 288.23 2,418.8

351829116371201 14N/3E-13M1S 07/29/2008 2,131.30 287.50 2,418.8

351829116371201 14N/3E-13M1S 12/13/2010 2,123.00 295.77 2,418.8

351829116371201 14N/3E-13M1S 10/27/2011 2,121.30 297.51 2,418.8

351828116371201 14N/3E-13M2S 07/09/1997 2,098.10 319.89 2,418.0

351828116371201 14N/3E-13M2S 07/14/1997 2,098.10 319.95 2,418.0

351828116371201 14N/3E-13M2S 08/19/1997 2,092.50 325.50 2,418.0

351828116371201 14N/3E-13M2S 08/25/1997 2,096.00 321.97 2,418.0

351828116371201 14N/3E-13M2S 09/03/1997 2,094.10 323.86 2,418.0

351828116371201 14N/3E-13M2S 09/23/1997 2,095.20 322.79 2,418.0

351828116371201 14N/3E-13M2S 10/02/1997 2,095.00 323.02 2,418.0

351828116371201 14N/3E-13M2S 07/09/1999 2,085.30 332.67 2,418.0

351828116371201 14N/3E-13M2S 03/30/2000 2,120.50 297.52 2,418.0

351828116371201 14N/3E-13M2S 07/28/2000 2,123.70 294.26 2,418.0

351828116371201 14N/3E-13M2S 01/30/2002 2,085.10 332.86 2,418.0

351828116371201 14N/3E-13M2S 03/01/2005 2,124.40 293.58 2,418.0

351828116371201 14N/3E-13M2S 11/06/2007 2,130.10 287.90 2,418.0

351828116371201 14N/3E-13M2S 12/19/2007 2,130.20 287.75 2,418.0

351828116371201 14N/3E-13M2S 02/13/2008 2,131.20 286.82 2,418.0

351828116371201 14N/3E-13M2S 04/29/2008 2,131.30 286.67 2,418.0

351828116371201 14N/3E-13M2S 07/29/2008 2,131.30 286.66 2,418.0

351828116371201 14N/3E-13M2S 01/22/2009 2,132.10 285.92 2,418.0

351828116371201 14N/3E-13M2S 01/27/2009 2,131.80 286.25 2,418.0

351828116371201 14N/3E-13M2S 04/08/2009 2,132.30 285.73 2,418.0

351828116371201 14N/3E-13M2S 10/07/2009 2,106.10 311.94 2,418.0

351828116371201 14N/3E-13M2S 06/14/2010 2,128.30 289.72 2,418.0

351828116371201 14N/3E-13M2S 12/13/2010 2,123.80 294.23 2,418.0

351828116371201 14N/3E-13M2S 04/28/2011 2,122.90 295.05 2,418.0

351828116371201 14N/3E-13M2S 10/24/2011 2,122.40 295.55 2,418.0

351828116371201 14N/3E-13M2S 10/30/2011 2,122.60 295.37 2,418.0

351828116371201 14N/3E-13M2S 02/13/2012 2,114.30 303.73 2,418.0

351828116371201 14N/3E-13M2S 02/21/2012 2,121.30 296.72 2,418.0

351828116371201 14N/3E-13M2S 08/30/2012 2,114.20 303.84 2,418.0

351828116371201 14N/3E-13M2S 04/17/2013 2,118.20 299.79 2,418.0

351828116371201 14N/3E-13M2S 09/10/2013 2,103.40 314.55 2,418.0

351828116371201 14N/3E-13M2S 08/01/2014 2,101.50 316.51 2,418.0

351828116371201 14N/3E-13M2S 11/06/2014 2,114.20 303.83 2,418.0

351828116371201 14N/3E-13M2S 02/18/2015 2,108.30 309.66 2,418.0

351828116371201 14N/3E-13M2S 05/20/2015 2,118.40 299.64 2,418.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 139

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA2-2

351828116371202 14N/3E-13M3S 07/09/1997 2,120.20 297.77 2,418.0

351828116371202 14N/3E-13M3S 07/14/1997 2,116.90 301.07 2,418.0

351828116371202 14N/3E-13M3S 08/25/1997 2,114.80 303.15 2,418.0

351828116371202 14N/3E-13M3S 09/03/1997 2,113.50 304.49 2,418.0

351828116371202 14N/3E-13M3S 09/23/1997 2,115.00 303.03 2,418.0

351828116371202 14N/3E-13M3S 10/02/1997 2,113.50 304.48 2,418.0

351828116371202 14N/3E-13M3S 07/09/1999 2,107.20 310.78 2,418.0

351828116371202 14N/3E-13M3S 03/30/2000 2,120.10 297.88 2,418.0

351828116371202 14N/3E-13M3S 07/28/2000 2,124.50 293.53 2,418.0

351828116371202 14N/3E-13M3S 01/30/2002 2,103.90 314.07 2,418.0

351828116371202 14N/3E-13M3S 03/01/2005 2,124.30 293.71 2,418.0

351828116371202 14N/3E-13M3S 11/06/2007 2,130.10 287.90 2,418.0

351828116371202 14N/3E-13M3S 12/19/2007 2,130.20 287.76 2,418.0

351828116371202 14N/3E-13M3S 02/13/2008 2,131.10 286.86 2,418.0

351828116371202 14N/3E-13M3S 04/29/2008 2,131.30 286.69 2,418.0

351828116371202 14N/3E-13M3S 07/29/2008 2,131.30 286.67 2,418.0

351828116371202 14N/3E-13M3S 01/22/2009 2,132.10 285.92 2,418.0

351828116371202 14N/3E-13M3S 01/27/2009 2,131.70 286.30 2,418.0

351828116371202 14N/3E-13M3S 04/08/2009 2,132.20 285.75 2,418.0

351828116371202 14N/3E-13M3S 10/07/2009 2,124.90 293.13 2,418.0

351828116371202 14N/3E-13M3S 06/14/2010 2,128.40 289.62 2,418.0

351828116371202 14N/3E-13M3S 12/13/2010 2,123.90 294.08 2,418.0

351828116371202 14N/3E-13M3S 12/13/2010 2,123.30 294.69 2,418.0

351828116371202 14N/3E-13M3S 04/28/2011 2,122.80 295.16 2,418.0

351828116371202 14N/3E-13M3S 10/24/2011 2,122.20 295.76 2,418.0

351828116371202 14N/3E-13M3S 10/30/2011 2,122.50 295.54 2,418.0

351828116371202 14N/3E-13M3S 02/13/2012 2,122.30 295.65 2,418.0

351828116371202 14N/3E-13M3S 02/21/2012 2,121.60 296.41 2,418.0

351828116371202 14N/3E-13M3S 08/30/2012 2,115.20 302.75 2,418.0

351828116371202 14N/3E-13M3S 04/17/2013 2,118.00 300.02 2,418.0

351828116371202 14N/3E-13M3S 09/10/2013 2,115.90 302.08 2,418.0

351828116371202 14N/3E-13M3S 08/12/2014 2,113.10 304.94 2,418.0

351828116371202 14N/3E-13M3S 11/06/2014 2,113.80 304.20 2,418.0

351828116371202 14N/3E-13M3S 02/18/2015 2,115.30 302.66 2,418.0

351828116371202 14N/3E-13M3S 05/20/2015 2,118.20 299.85 2,418.0

Local ID: BLA2-3

351828116371203 14N/3E-13M4S 07/09/1997 2,118.60 299.38 2,418.0

351828116371203 14N/3E-13M4S 07/16/1997 2,117.30 300.70 2,418.0

351828116371203 14N/3E-13M4S 08/19/1997 2,115.60 302.38 2,418.0

351828116371203 14N/3E-13M4S 08/25/1997 2,116.00 302.02 2,418.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
140 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA2-3—Continued

351828116371203 14N/3E-13M4S 09/03/1997 2,114.60 303.43 2,418.0

351828116371203 14N/3E-13M4S 09/24/1997 2,114.60 303.40 2,418.0

351828116371203 14N/3E-13M4S 10/02/1997 2,114.20 303.83 2,418.0

351828116371203 14N/3E-13M4S 07/09/1999 2,107.40 310.60 2,418.0

351828116371203 14N/3E-13M4S 03/30/2000 2,119.90 298.14 2,418.0

351828116371203 14N/3E-13M4S 07/28/2000 2,124.30 293.73 2,418.0

351828116371203 14N/3E-13M4S 01/30/2002 2,104.00 314.01 2,418.0

351828116371203 14N/3E-13M4S 03/01/2005 2,124.20 293.79 2,418.0

351828116371203 14N/3E-13M4S 11/06/2007 2,130.10 287.93 2,418.0

351828116371203 14N/3E-13M4S 12/19/2007 2,130.20 287.83 2,418.0

351828116371203 14N/3E-13M4S 02/13/2008 2,131.10 286.91 2,418.0

351828116371203 14N/3E-13M4S 04/29/2008 2,131.30 286.74 2,418.0

351828116371203 14N/3E-13M4S 07/29/2008 2,131.30 286.71 2,418.0

351828116371203 14N/3E-13M4S 01/22/2009 2,132.10 285.93 2,418.0

351828116371203 14N/3E-13M4S 01/27/2009 2,131.70 286.34 2,418.0

351828116371203 14N/3E-13M4S 04/08/2009 2,132.20 285.80 2,418.0

351828116371203 14N/3E-13M4S 10/07/2009 2,126.00 292.04 2,418.0

351828116371203 14N/3E-13M4S 06/14/2010 2,128.70 289.27 2,418.0

351828116371203 14N/3E-13M4S 12/13/2010 2,123.20 294.85 2,418.0

351828116371203 14N/3E-13M4S 12/13/2010 2,123.10 294.89 2,418.0

351828116371203 14N/3E-13M4S 04/28/2011 2,122.90 295.07 2,418.0

351828116371203 14N/3E-13M4S 10/24/2011 2,122.10 295.92 2,418.0

351828116371203 14N/3E-13M4S 10/30/2011 2,122.20 295.75 2,418.0

351828116371203 14N/3E-13M4S 02/13/2012 2,121.30 296.73 2,418.0

351828116371203 14N/3E-13M4S 02/21/2012 2,121.90 296.05 2,418.0

351828116371203 14N/3E-13M4S 08/30/2012 2,115.80 302.19 2,418.0

351828116371203 14N/3E-13M4S 04/17/2013 2,117.80 300.23 2,418.0

351828116371203 14N/3E-13M4S 09/10/2013 2,116.30 301.70 2,418.0

351828116371203 14N/3E-13M4S 08/01/2014 2,114.40 303.60 2,418.0

351828116371203 14N/3E-13M4S 11/06/2014 2,113.60 304.45 2,418.0

351828116371203 14N/3E-13M4S 02/18/2015 2,114.90 303.07 2,418.0

351828116371203 14N/3E-13M4S 05/20/2015 2,118.00 300.03 2,418.0

Local ID: B-2

351830116372601 14N/3E-14H1S 11/14/1964 2,220.60 202.00 2,422.6

351830116372601 14N/3E-14H1S 03/01/1967 2,192.60 230.00 2,422.6

351830116372601 14N/3E-14H1S 01/01/1968 2,193.60 229.00 2,422.6

351830116372601 14N/3E-14H1S 01/01/1969 2,180.60 242.00 2,422.6

351830116372601 14N/3E-14H1S 03/01/1970 2,182.60 240.00 2,422.6

351830116372601 14N/3E-14H1S 02/01/1974 2,185.60 237.00 2,422.6

351830116372601 14N/3E-14H1S 09/01/1978 2,169.60 253.00 2,422.6

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 141

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: B-2—Continued

351830116372601 14N/3E-14H1S 01/01/1981 2,159.60 263.00 2,422.6

351830116372601 14N/3E-14H1S 01/26/1993 2,123.40 299.18 2,422.6

351830116372601 14N/3E-14H1S 07/21/1994 2,122.20 300.44 2,422.6

351830116372601 14N/3E-14H1S 09/08/1994 2,121.10 301.53 2,422.6

351830116372601 14N/3E-14H1S 12/20/1994 2,123.20 299.43 2,422.6

351830116372601 14N/3E-14H1S 03/03/1995 2,124.10 298.50 2,422.6

351830116372601 14N/3E-14H1S 08/03/1995 2,126.40 296.20 2,422.6

351830116372601 14N/3E-14H1S 09/18/1996 2,125.50 297.14 2,422.6

351830116372601 14N/3E-14H1S 08/20/1997 2,121.40 301.24 2,422.6

351830116372601 14N/3E-14H1S 09/03/1997 2,119.80 302.75 2,422.6

351830116372601 14N/3E-14H1S 09/08/1997 2,120.40 302.22 2,422.6

351830116372601 14N/3E-14H1S 10/07/1997 2,119.50 303.14 2,422.6

351830116372601 14N/3E-14H1S 07/09/1999 2,115.70 306.93 2,422.6

351830116372601 14N/3E-14H1S 03/30/2000 2,121.30 301.32 2,422.6

351830116372601 14N/3E-14H1S 07/28/2000 2,124.20 298.45 2,422.6

Local ID: B-6

351810116375701 14N/3E-14P1S 03/01/1988 2,203.90 176.00 2,379.9

351810116375701 14N/3E-14P1S 05/01/1988 2,211.90 168.00 2,379.9

351810116375701 14N/3E-14P1S 01/26/1993 2,205.70 174.20 2,379.9

351810116375701 14N/3E-14P1S 07/21/1994 2,203.30 176.59 2,379.9

351810116375701 14N/3E-14P1S 09/07/1994 2,208.10 171.80 2,379.9

351810116375701 14N/3E-14P1S 11/22/1994 2,202.90 177.00 2,379.9

351810116375701 14N/3E-14P1S 03/03/1995 2,201.70 178.16 2,379.9

351810116375701 14N/3E-14P1S 07/09/1999 2,175.90 203.96 2,379.9

351810116375701 14N/3E-14P1S 02/14/2008 2,130.60 249.30 2,379.9

351810116375701 14N/3E-14P1S 10/27/2011 2,119.00 260.95 2,379.9

351810116375701 14N/3E-14P1S 03/28/2012 2,105.20 274.70 2,379.9

Local ID: TH-7

351809116375901 14N/3E-14P2S 01/30/1988 2,213.20 166.00 2,379.2

351809116375901 14N/3E-14P2S 05/01/1988 2,212.20 167.00 2,379.2

351809116375901 14N/3E-14P2S 01/26/1993 2,205.70 173.48 2,379.2

351809116375901 14N/3E-14P2S 09/07/1994 2,203.40 175.82 2,379.2

351809116375901 14N/3E-14P2S 11/22/1994 2,203.10 176.08 2,379.2

351809116375901 14N/3E-14P2S 03/03/1995 2,203.10 176.07 2,379.2

351809116375901 14N/3E-14P2S 08/03/1995 2,202.30 176.94 2,379.2

351809116375901 14N/3E-14P2S 09/08/1997 2,144.90 234.31 2,379.2

351809116375901 14N/3E-14P2S 10/07/1997 2,144.10 235.05 2,379.2

351809116375901 14N/3E-14P2S 07/09/1999 2,176.30 202.88 2,379.2

351809116375901 14N/3E-14P2S 03/30/2000 2,124.30 254.92 2,379.2

351809116375901 14N/3E-14P2S 07/28/2000 2,120.00 259.22 2,379.2

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
142 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: TH-7—Continued

351809116375901 14N/3E-14P2S 01/30/2002 2,155.70 223.49 2,379.2

351809116375901 14N/3E-14P2S 03/01/2005 2,113.10 266.10 2,379.2

351809116375901 14N/3E-14P2S 03/02/2005 2,130.60 248.59 2,379.2

351809116375901 14N/3E-14P2S 11/06/2007 2,092.00 287.23 2,379.2

351809116375901 14N/3E-14P2S 12/19/2007 2,124.20 255.04 2,379.2

351809116375901 14N/3E-14P2S 02/14/2008 2,130.90 248.28 2,379.2

351809116375901 14N/3E-14P2S 04/29/2008 2,110.40 268.83 2,379.2

351809116375901 14N/3E-14P2S 07/29/2008 2,092.40 286.83 2,379.2

351809116375901 14N/3E-14P2S 01/22/2009 2,101.30 277.93 2,379.2

351809116375901 14N/3E-14P2S 01/27/2009 2,100.00 279.24 2,379.2

351809116375901 14N/3E-14P2S 04/07/2009 2,110.40 268.84 2,379.2

351809116375901 14N/3E-14P2S 10/07/2009 2,089.60 289.61 2,379.2

351809116375901 14N/3E-14P2S 10/09/2009 2,089.50 289.68 2,379.2

351809116375901 14N/3E-14P2S 06/15/2010 2,095.30 283.90 2,379.2

351809116375901 14N/3E-14P2S 12/12/2010 2,110.70 268.48 2,379.2

351809116375901 14N/3E-14P2S 04/28/2011 2,107.20 271.96 2,379.2

351809116375901 14N/3E-14P2S 10/24/2011 2,118.80 260.42 2,379.2

351809116375901 14N/3E-14P2S 10/30/2011 2,119.60 259.62 2,379.2

351809116375901 14N/3E-14P2S 02/13/2012 2,099.40 279.75 2,379.2

351809116375901 14N/3E-14P2S 02/21/2012 2,099.70 279.51 2,379.2

351809116375901 14N/3E-14P2S 08/30/2012 2,085.90 293.34 2,379.2

351809116375901 14N/3E-14P2S 04/17/2013 2,124.80 254.39 2,379.2

351809116375901 14N/3E-14P2S 09/10/2013 2,130.00 249.15 2,379.2

351809116375901 14N/3E-14P2S 08/01/2014 2,096.80 282.45 2,379.2

351809116375901 14N/3E-14P2S 02/18/2015 2,109.10 270.06 2,379.2

Local ID: BA1-1

351710116392701 14N/3E-22N1S 05/19/1993 2,247.30 170.96 2,418.3

351710116392701 14N/3E-22N1S 09/23/1993 2,246.90 171.41 2,418.3

351710116392701 14N/3E-22N1S 07/21/1994 2,246.90 171.45 2,418.3

351710116392701 14N/3E-22N1S 09/08/1994 2,246.70 171.56 2,418.3

351710116392701 14N/3E-22N1S 09/21/1994 2,246.70 171.56 2,418.3

351710116392701 14N/3E-22N1S 11/22/1994 2,246.60 171.71 2,418.3

351710116392701 14N/3E-22N1S 03/04/1995 2,246.70 171.60 2,418.3

351710116392701 14N/3E-22N1S 08/03/1995 2,246.70 171.62 2,418.3

351710116392701 14N/3E-22N1S 05/22/1996 2,246.80 171.54 2,418.3

351710116392701 14N/3E-22N1S 06/12/1996 2,246.70 171.64 2,418.3

351710116392701 14N/3E-22N1S 07/17/1997 2,246.60 171.74 2,418.3

351710116392701 14N/3E-22N1S 07/07/1999 2,246.30 171.98 2,418.3

351710116392701 14N/3E-22N1S 03/30/2000 2,246.40 171.91 2,418.3

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 143

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: B-3

351719116390301 14N/3E-22P1S 01/26/1993 2,243.00 189.18 2,432.0

351719116390301 14N/3E-22P1S 07/21/1994 2,242.00 189.81 2,432.0

351719116390301 14N/3E-22P1S 09/08/1994 2,242.00 190.23 2,432.0

351719116390301 14N/3E-22P1S 11/22/1994 2,241.00 190.63 2,432.0

351719116390301 14N/3E-22P1S 03/04/1995 2,242.00 190.42 2,432.0

351719116390301 14N/3E-22P1S 08/03/1995 2,241.00 190.67 2,432.0

351719116390301 14N/3E-22P1S 09/18/1996 2,240.00 191.51 2,432.0

Local ID: BLA4-1

351759116374401 14N/3E-23B1S 04/30/2008 2,147.00 229.77 2,377.0

351759116374401 14N/3E-23B1S 07/29/2008 2,141.00 235.86 2,377.0

351759116374401 14N/3E-23B1S 01/22/2009 2,144.00 232.61 2,377.0

351759116374401 14N/3E-23B1S 01/27/2009 2,144.00 233.04 2,377.0

351759116374401 14N/3E-23B1S 04/07/2009 2,140.00 236.59 2,377.0

351759116374401 14N/3E-23B1S 10/08/2009 2,136.00 240.72 2,377.0

351759116374401 14N/3E-23B1S 03/02/2010 2,145.00 232.48 2,377.0

351759116374401 14N/3E-23B1S 03/02/2010 2,144.00 232.52 2,377.0

351759116374401 14N/3E-23B1S 06/15/2010 2,142.00 234.73 2,377.0

351759116374401 14N/3E-23B1S 12/14/2010 2,136.00 240.58 2,377.0

351759116374401 14N/3E-23B1S 12/14/2010 2,136.00 240.51 2,377.0

351759116374401 14N/3E-23B1S 12/17/2010 2,136.00 240.61 2,377.0

351759116374401 14N/3E-23B1S 12/17/2010 2,136.00 240.65 2,377.0

351759116374401 14N/3E-23B1S 04/28/2011 2,134.00 242.51 2,377.0

351759116374401 14N/3E-23B1S 10/24/2011 2,136.00 241.31 2,377.0

351759116374401 14N/3E-23B1S 10/30/2011 2,136.00 241.16 2,377.0

351759116374401 14N/3E-23B1S 02/13/2012 2,139.00 237.86 2,377.0

351759116374401 14N/3E-23B1S 02/21/2012 2,139.00 238.21 2,377.0

351759116374401 14N/3E-23B1S 08/30/2012 2,131.00 245.85 2,377.0

351759116374401 14N/3E-23B1S 04/17/2013 2,138.00 238.92 2,377.0

351759116374401 14N/3E-23B1S 09/10/2013 2,142.00 234.55 2,377.0

351759116374401 14N/3E-23B1S 08/01/2014 2,136.00 241.34 2,377.0

351759116374401 14N/3E-23B1S 11/03/2014 2,135.00 242.37 2,377.0

351759116374401 14N/3E-23B1S 02/10/2015 2,140.00 236.88 2,377.0

351759116374401 14N/3E-23B1S 02/16/2015 2,140.00 236.62 2,377.0

351759116374401 14N/3E-23B1S 5/21/2015 2,140.00 237.05 2,377.0

Local ID: BLA4-2

351759116374402 14N/3E-23B2S 04/30/2008 2,133.00 243.61 2,377.0

351759116374402 14N/3E-23B2S 07/29/2008 2,109.00 268.07 2,377.0

351759116374402 14N/3E-23B2S 01/22/2009 2,117.00 259.85 2,377.0

351759116374402 14N/3E-23B2S 01/27/2009 2,115.00 262.10 2,377.0

351759116374402 14N/3E-23B2S 04/07/2009 2,109.00 268.28 2,377.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
144 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA4-2—Continued

351759116374402 14N/3E-23B2S 10/08/2009 2,105.00 272.16 2,377.0

351759116374402 14N/3E-23B2S 03/02/2010 2,134.00 243.05 2,377.0

351759116374402 14N/3E-23B2S 03/02/2010 2,134.00 243.19 2,377.0

351759116374402 14N/3E-23B2S 06/15/2010 2,110.00 266.90 2,377.0

351759116374402 14N/3E-23B2S 12/14/2010 2,109.00 267.57 2,377.0

351759116374402 14N/3E-23B2S 12/14/2010 2,109.00 267.98 2,377.0

351759116374402 14N/3E-23B2S 04/27/2011 2,105.00 272.43 2,377.0

351759116374402 14N/3E-23B2S 10/24/2011 2,118.00 259.04 2,377.0

351759116374402 14N/3E-23B2S 10/30/2011 2,120.00 257.05 2,377.0

351759116374402 14N/3E-23B2S 02/13/2012 2,117.00 259.90 2,377.0

351759116374402 14N/3E-23B2S 02/21/2012 2,113.00 263.97 2,377.0

351759116374402 14N/3E-23B2S 08/30/2012 2,101.00 275.67 2,377.0

351759116374402 14N/3E-23B2S 04/17/2013 2,126.00 250.74 2,377.0

351759116374402 14N/3E-23B2S 09/10/2013 2,131.00 246.12 2,377.0

351759116374402 14N/3E-23B2S 08/01/2014 2,109.00 268.24 2,377.0

351759116374402 14N/3E-23B2S 11/03/2014 2,124.00 253.27 2,377.0

351759116374402 14N/3E-23B2S 02/10/2015 2,130.00 246.80 2,377.0

351759116374402 14N/3E-23B2S 02/16/2015 2,121.00 256.47 2,377.0

351759116374402 14N/3E-23B2S 02/17/2015 2,120.00 257.16 2,377.0

351759116374402 14N/3E-23B2S 05/20/2015 2,130.00 247.05 2,377.0

Local ID: BLA4-3

351759116374403 14N/3E-23B3S 04/30/2008 2,145.00 231.64 2,377.0

351759116374403 14N/3E-23B3S 07/29/2008 2,144.00 233.17 2,377.0

351759116374403 14N/3E-23B3S 01/22/2009 2,144.00 233.02 2,377.0

351759116374403 14N/3E-23B3S 01/27/2009 2,143.00 233.51 2,377.0

351759116374403 14N/3E-23B3S 04/07/2009 2,143.00 233.95 2,377.0

351759116374403 14N/3E-23B3S 10/08/2009 2,142.00 235.04 2,377.0

351759116374403 14N/3E-23B3S 03/02/2010 2,143.00 234.01 2,377.0

351759116374403 14N/3E-23B3S 03/02/2010 2,143.00 234.05 2,377.0

351759116374403 14N/3E-23B3S 06/15/2010 2,142.00 234.71 2,377.0

351759116374403 14N/3E-23B3S 12/14/2010 2,141.00 235.64 2,377.0

351759116374403 14N/3E-23B3S 12/14/2010 2,141.00 236.10 2,377.0

351759116374403 14N/3E-23B3S 04/28/2011 2,139.00 237.77 2,377.0

351759116374403 14N/3E-23B3S 10/24/2011 2,140.00 237.28 2,377.0

351759116374403 14N/3E-23B3S 10/30/2011 2,140.00 237.42 2,377.0

351759116374403 14N/3E-23B3S 02/13/2012 2,140.00 237.02 2,377.0

351759116374403 14N/3E-23B3S 02/21/2012 2,139.00 237.65 2,377.0

351759116374403 14N/3E-23B3S 08/30/2012 2,138.00 238.87 2,377.0

351759116374403 14N/3E-23B3S 04/17/2013 2,138.00 239.40 2,377.0

351759116374403 14N/3E-23B3S 09/10/2013 2,139.00 238.34 2,377.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 145

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA4-3—Continued

351759116374403 14N/3E-23B3S 08/01/2014 2,138.00 239.13 2,377.0

351759116374403 14N/3E-23B3S 11/03/2014 2,137.00 239.79 2,377.0

351759116374403 14N/3E-23B3S 02/10/2015 2,138.00 239.04 2,377.0

351759116374403 14N/3E-23B3S 02/15/2015 2,138.00 239.03 2,377.0

351759116374403 14N/3E-23B3S 02/17/2015 2,138.00 239.22 2,377.0

351759116374403 14N/3E-23B3S 05/20/2015 2,138.00 239.15 2,377.0

Local ID: BX-2

351738116374101 14N/3E-23G1S 10/30/1980 2,205.00 155.60 2,360.6

351738116374101 14N/3E-23G1S 01/26/1993 2,214.90 145.67 2,360.6

351738116374101 14N/3E-23G1S 09/24/1993 2,214.10 146.47 2,360.6

351738116374101 14N/3E-23G1S 07/21/1994 2,213.50 147.11 2,360.6

351738116374101 14N/3E-23G1S 09/08/1994 2,213.40 147.23 2,360.6

351738116374101 14N/3E-23G1S 09/21/1994 2,213.20 147.36 2,360.6

351738116374101 14N/3E-23G1S 11/22/1994 2,212.80 147.78 2,360.6

351738116374101 14N/3E-23G1S 02/02/1995 2,213.00 147.57 2,360.6

351738116374101 14N/3E-23G1S 03/03/1995 2,212.90 147.72 2,360.6

351738116374101 14N/3E-23G1S 09/18/1996 2,211.00 149.57 2,360.6

351738116374101 14N/3E-23G1S 07/08/1997 2,210.10 150.53 2,360.6

351738116374101 14N/3E-23G1S 09/04/1997 2,209.10 151.46 2,360.6

351738116374101 14N/3E-23G1S 09/08/1997 2,209.80 150.75 2,360.6

351738116374101 14N/3E-23G1S 10/07/1997 2,210.10 150.49 2,360.6

351738116374101 14N/3E-23G1S 07/29/1999 2,204.20 156.35 2,360.6

351738116374101 14N/3E-23G1S 03/30/2000 2,201.60 159.02 2,360.6

351738116374101 14N/3E-23G1S 08/01/2000 2,200.40 160.20 2,360.6

351738116374101 14N/3E-23G1S 01/30/2002 2,195.30 165.29 2,360.6

351738116374101 14N/3E-23G1S 03/01/2005 2,186.10 174.52 2,360.6

351738116374101 14N/3E-23G1S 11/06/2007 2,176.80 183.83 2,360.6

351738116374101 14N/3E-23G1S 12/18/2007 2,179.50 181.12 2,360.6

351738116374101 14N/3E-23G1S 02/15/2008 2,179.00 181.58 2,360.6

351738116374101 14N/3E-23G1S 04/29/2008 2,178.80 181.78 2,360.6

351738116374101 14N/3E-23G1S 07/29/2008 2,177.70 182.90 2,360.6

351738116374101 14N/3E-23G1S 01/22/2009 2,176.60 183.98 2,360.6

351738116374101 14N/3E-23G1S 04/07/2009 2,175.90 184.65 2,360.6

351738116374101 14N/3E-23G1S 10/07/2009 2,174.40 186.19 2,360.6

351738116374101 14N/3E-23G1S 06/14/2010 2,172.90 187.65 2,360.6

351738116374101 14N/3E-23G1S 12/14/2010 2,171.70 188.88 2,360.6

351738116374101 14N/3E-23G1S 12/14/2010 2,171.80 188.75 2,360.6

351738116374101 14N/3E-23G1S 04/27/2011 2,170.80 189.75 2,360.6

351738116374101 14N/3E-23G1S 10/24/2011 2,170.20 190.35 2,360.6

351738116374101 14N/3E-23G1S 10/30/2011 2,170.00 190.56 2,360.6

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
146 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BX-2—Continued

351738116374101 14N/3E-23G1S 02/13/2012 2,170.00 190.60 2,360.6

351738116374101 14N/3E-23G1S 02/21/2012 2,169.50 191.06 2,360.6

351738116374101 14N/3E-23G1S 08/30/2012 2,169.00 191.64 2,360.6

351738116374101 14N/3E-23G1S 04/17/2013 2,167.90 192.66 2,360.6

351738116374101 14N/3E-23G1S 09/10/2013 2,167.80 192.77 2,360.6

351738116374101 14N/3E-23G1S 08/01/2014 2,167.00 193.59 2,360.6

351738116374101 14N/3E-23G1S 12/09/2014 2,166.80 193.83 2,360.6

351738116374101 14N/3E-23G1S 02/17/2015 2,166.50 194.11 2,360.6

351738116374101 14N/3E-23G1S 05/20/2015 2,166.40 194.24 2,360.6

Local ID: BX-1

351742116362401 14N/3E-24H1S 10/30/1980 2,218.90 142.70 2,361.6

351742116362401 14N/3E-24H1S 01/26/1993 2,193.80 167.81 2,361.6

351742116362401 14N/3E-24H1S 07/29/1993 2,192.00 169.56 2,361.6

351742116362401 14N/3E-24H1S 07/21/1994 2,190.00 171.60 2,361.6

351742116362401 14N/3E-24H1S 07/27/1994 2,189.60 171.99 2,361.6

351742116362401 14N/3E-24H1S 09/08/1994 2,189.30 172.30 2,361.6

351742116362401 14N/3E-24H1S 09/19/1994 2,189.30 172.27 2,361.6

351742116362401 14N/3E-24H1S 12/20/1994 2,189.40 172.18 2,361.6

351742116362401 14N/3E-24H1S 01/31/1995 2,189.80 171.84 2,361.6

351742116362401 14N/3E-24H1S 03/03/1995 2,189.60 171.99 2,361.6

351742116362401 14N/3E-24H1S 08/03/1995 2,188.50 173.13 2,361.6

351742116362401 14N/3E-24H1S 09/18/1996 2,183.00 178.57 2,361.6

Local ID: BLA3-1

351716116363701 14N/3E-24Q1S 07/14/1997 2,151.50 204.17 2,355.7

351716116363701 14N/3E-24Q1S 07/22/1997 2,189.60 166.05 2,355.7

351716116363701 14N/3E-24Q1S 09/08/1997 2,190.70 164.99 2,355.7

351716116363701 14N/3E-24Q1S 07/08/1999 2,186.40 169.31 2,355.7

351716116363701 14N/3E-24Q1S 03/30/2000 2,183.60 172.14 2,355.7

351716116363701 14N/3E-24Q1S 01/30/2002 2,179.30 176.39 2,355.7

351716116363701 14N/3E-24Q1S 03/01/2005 2,168.80 186.93 2,355.7

351716116363701 14N/3E-24Q1S 11/06/2007 2,164.00 191.70 2,355.7

351716116363701 14N/3E-24Q1S 12/19/2007 2,163.60 192.07 2,355.7

351716116363701 14N/3E-24Q1S 02/14/2008 2,163.80 191.85 2,355.7

351716116363701 14N/3E-24Q1S 04/30/2008 2,164.10 191.56 2,355.7

351716116363701 14N/3E-24Q1S 07/28/2008 2,163.00 192.72 2,355.7

351716116363701 14N/3E-24Q1S 01/22/2009 2,162.20 193.48 2,355.7

351716116363701 14N/3E-24Q1S 01/26/2009 2,162.10 193.60 2,355.7

351716116363701 14N/3E-24Q1S 04/08/2009 2,161.20 194.48 2,355.7

351716116363701 14N/3E-24Q1S 10/07/2009 2,159.80 195.86 2,355.7

351716116363701 14N/3E-24Q1S 06/14/2010 2,159.80 195.94 2,355.7

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 147

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA3-1—Continued

351716116363701 14N/3E-24Q1S 12/17/2010 2,158.30 197.44 2,355.7

351716116363701 14N/3E-24Q1S 04/27/2011 2,157.10 198.63 2,355.7

351716116363701 14N/3E-24Q1S 10/24/2011 2,155.80 199.85 2,355.7

351716116363701 14N/3E-24Q1S 10/30/2011 2,156.00 199.65 2,355.7

351716116363701 14N/3E-24Q1S 02/13/2012 2,156.30 199.40 2,355.7

351716116363701 14N/3E-24Q1S 02/21/2012 2,156.00 199.69 2,355.7

351716116363701 14N/3E-24Q1S 08/30/2012 2,153.90 201.77 2,355.7

351716116363701 14N/3E-24Q1S 04/17/2013 2,153.70 201.98 2,355.7

351716116363701 14N/3E-24Q1S 09/10/2013 2,154.80 200.92 2,355.7

351716116363701 14N/3E-24Q1S 08/01/2014 2,153.20 202.51 2,355.7

351716116363701 14N/3E-24Q1S 11/04/2014 2,151.90 203.76 2,355.7

351716116363701 14N/3E-24Q1S 02/16/2015 2,152.70 203.04 2,355.7

351716116363701 14N/3E-24Q1S 05/21/2015 2,152.30 203.36 2,355.7

Local ID: BLA3-2

351716116363702 14N/3E-24Q2S 07/14/1997 2,153.50 202.21 2,355.7

351716116363702 14N/3E-24Q2S 07/23/1997 2,190.20 165.46 2,355.7

351716116363702 14N/3E-24Q2S 09/08/1997 2,190.40 165.29 2,355.7

351716116363702 14N/3E-24Q2S 07/08/1999 2,185.70 169.99 2,355.7

351716116363702 14N/3E-24Q2S 03/30/2000 2,181.90 173.80 2,355.7

351716116363702 14N/3E-24Q2S 01/30/2002 2,178.40 177.30 2,355.7

351716116363702 14N/3E-24Q2S 03/01/2005 2,168.10 187.57 2,355.7

351716116363702 14N/3E-24Q2S 11/06/2007 2,162.80 192.85 2,355.7

351716116363702 14N/3E-24Q2S 12/19/2007 2,162.80 192.95 2,355.7

351716116363702 14N/3E-24Q2S 02/14/2008 2,163.10 192.61 2,355.7

351716116363702 14N/3E-24Q2S 04/30/2008 2,163.60 192.12 2,355.7

351716116363702 14N/3E-24Q2S 07/28/2008 2,161.90 193.78 2,355.7

351716116363702 14N/3E-24Q2S 01/22/2009 2,161.40 194.31 2,355.7

351716116363702 14N/3E-24Q2S 01/26/2009 2,161.20 194.47 2,355.7

351716116363702 14N/3E-24Q2S 04/08/2009 2,160.20 195.48 2,355.7

351716116363702 14N/3E-24Q2S 10/07/2009 2,158.80 196.88 2,355.7

351716116363702 14N/3E-24Q2S 06/14/2010 2,159.00 196.74 2,355.7

351716116363702 14N/3E-24Q2S 12/17/2010 2,157.20 198.46 2,355.7

351716116363702 14N/3E-24Q2S 04/27/2011 2,156.20 199.47 2,355.7

351716116363702 14N/3E-24Q2S 10/24/2011 2,155.10 200.64 2,355.7

351716116363702 14N/3E-24Q2S 10/30/2011 2,155.20 200.45 2,355.7

351716116363702 14N/3E-24Q2S 02/13/2012 2,155.60 200.07 2,355.7

351716116363702 14N/3E-24Q2S 02/21/2012 2,155.20 200.45 2,355.7

351716116363702 14N/3E-24Q2S 08/30/2012 2,152.80 202.90 2,355.7

351716116363702 14N/3E-24Q2S 04/17/2013 2,153.20 202.50 2,355.7

351716116363702 14N/3E-24Q2S 09/10/2013 2,154.40 201.28 2,355.7

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
148 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA3-2—Continued

351716116363702 14N/3E-24Q2S 08/01/2014 2,152.20 203.49 2,355.7

351716116363702 14N/3E-24Q2S 11/04/2014 2,151.10 204.57 2,355.7

351716116363702 14N/3E-24Q2S 02/09/2015 2,152.20 203.54 2,355.7

351716116363702 14N/3E-24Q2S 02/16/2015 2,152.00 203.69 2,355.7

351716116363702 14N/3E-24Q2S 05/21/2015 2,151.80 203.95 2,355.7

Local ID: BLA3-3

351716116363703 14N/3E-24Q3S 07/14/1997 2,165.20 190.46 2,355.7

351716116363703 14N/3E-24Q3S 07/23/1997 2,189.80 165.90 2,355.7

351716116363703 14N/3E-24Q3S 09/08/1997 2,189.20 166.50 2,355.7

351716116363703 14N/3E-24Q3S 07/08/1999 2,184.60 171.10 2,355.7

351716116363703 14N/3E-24Q3S 03/30/2000 2,181.30 174.37 2,355.7

351716116363703 14N/3E-24Q3S 01/30/2002 2,176.90 178.76 2,355.7

351716116363703 14N/3E-24Q3S 03/01/2005 2,166.60 189.14 2,355.7

351716116363703 14N/3E-24Q3S 11/06/2007 2,161.00 194.74 2,355.7

351716116363703 14N/3E-24Q3S 12/19/2007 2,160.90 194.75 2,355.7

351716116363703 14N/3E-24Q3S 02/14/2008 2,161.50 194.21 2,355.7

351716116363703 14N/3E-24Q3S 04/30/2008 2,162.20 193.53 2,355.7

351716116363703 14N/3E-24Q3S 07/28/2008 2,160.20 195.52 2,355.7

351716116363703 14N/3E-24Q3S 01/22/2009 2,159.80 195.89 2,355.7

351716116363703 14N/3E-24Q3S 01/26/2009 2,159.60 196.09 2,355.7

351716116363703 14N/3E-24Q3S 04/08/2009 2,158.50 197.20 2,355.7

351716116363703 14N/3E-24Q3S 10/07/2009 2,157.00 198.65 2,355.7

351716116363703 14N/3E-24Q3S 06/14/2010 2,157.50 198.23 2,355.7

351716116363703 14N/3E-24Q3S 12/17/2010 2,155.50 200.20 2,355.7

351716116363703 14N/3E-24Q3S 04/27/2011 2,154.30 201.42 2,355.7

351716116363703 14N/3E-24Q3S 10/24/2011 2,153.40 202.29 2,355.7

351716116363703 14N/3E-24Q3S 10/30/2011 2,153.60 202.11 2,355.7

351716116363703 14N/3E-24Q3S 02/13/2012 2,154.10 201.60 2,355.7

351716116363703 14N/3E-24Q3S 02/21/2012 2,153.70 201.97 2,355.7

351716116363703 14N/3E-24Q3S 08/30/2012 2,151.00 204.68 2,355.7

351716116363703 14N/3E-24Q3S 04/17/2013 2,151.80 203.88 2,355.7

351716116363703 14N/3E-24Q3S 09/10/2013 2,153.30 202.41 2,355.7

351716116363703 14N/3E-24Q3S 08/01/2014 2,150.60 205.12 2,355.7

351716116363703 14N/3E-24Q3S 11/04/2014 2,149.50 206.19 2,355.7

351716116363703 14N/3E-24Q3S 02/09/2015 2,150.80 204.87 2,355.7

351716116363703 14N/3E-24Q3S 02/16/2015 2,150.80 204.95 2,355.7

351716116363703 14N/3E-24Q3S 05/20/2015 2,150.40 205.29 2,355.7

Local ID: BLA3-4

351716116363704 14N/3E-24Q4S 07/14/1997 2,175.80 179.89 2,355.7

351716116363704 14N/3E-24Q4S 07/24/1997 2,189.10 166.55 2,355.7

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 149

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA3-4—Continued

351716116363704 14N/3E-24Q4S 09/08/1997 2,188.60 167.09 2,355.7

351716116363704 14N/3E-24Q4S 07/08/1999 2,183.80 171.94 2,355.7

351716116363704 14N/3E-24Q4S 03/30/2000 2,180.40 175.32 2,355.7

351716116363704 14N/3E-24Q4S 01/30/2002 2,175.90 179.83 2,355.7

351716116363704 14N/3E-24Q4S 03/01/2005 2,165.50 190.21 2,355.7

351716116363704 14N/3E-24Q4S 11/06/2007 2,159.80 195.92 2,355.7

351716116363704 14N/3E-24Q4S 12/19/2007 2,159.80 195.90 2,355.7

351716116363704 14N/3E-24Q4S 02/14/2008 2,160.40 195.25 2,355.7

351716116363704 14N/3E-24Q4S 04/30/2008 2,161.10 194.55 2,355.7

351716116363704 14N/3E-24Q4S 07/28/2008 2,159.10 196.61 2,355.7

351716116363704 14N/3E-24Q4S 01/22/2009 2,158.70 196.96 2,355.7

351716116363704 14N/3E-24Q4S 01/26/2009 2,158.60 197.14 2,355.7

351716116363704 14N/3E-24Q4S 04/08/2009 2,157.40 198.31 2,355.7

351716116363704 14N/3E-24Q4S 10/07/2009 2,155.90 199.82 2,355.7

351716116363704 14N/3E-24Q4S 06/14/2010 2,156.60 199.10 2,355.7

351716116363704 14N/3E-24Q4S 12/17/2010 2,154.40 201.30 2,355.7

351716116363704 14N/3E-24Q4S 04/27/2011 2,153.20 202.49 2,355.7

351716116363704 14N/3E-24Q4S 10/24/2011 2,152.30 203.38 2,355.7

351716116363704 14N/3E-24Q4S 10/25/2011 2,152.50 203.24 2,355.7

351716116363704 14N/3E-24Q4S 02/13/2012 2,153.10 202.64 2,355.7

351716116363704 14N/3E-24Q4S 02/21/2012 2,152.70 202.96 2,355.7

351716116363704 14N/3E-24Q4S 08/30/2012 2,149.90 205.80 2,355.7

351716116363704 14N/3E-24Q4S 04/17/2013 2,150.90 204.80 2,355.7

351716116363704 14N/3E-24Q4S 09/10/2013 2,152.50 203.22 2,355.7

351716116363704 14N/3E-24Q4S 08/01/2014 2,149.60 206.14 2,355.7

351716116363704 14N/3E-24Q4S 11/04/2014 2,148.60 207.11 2,355.7

351716116363704 14N/3E-24Q4S 02/09/2015 2,150.00 205.66 2,355.7

351716116363704 14N/3E-24Q4S 02/16/2015 2,149.90 205.82 2,355.7

351716116363704 14N/3E-24Q4S 05/20/2015 2,149.50 206.16 2,355.7

Local ID: BLA3-5

351716116363705 14N/3E-24Q5S 07/14/1997 2,184.60 171.05 2,355.7

351716116363705 14N/3E-24Q5S 07/24/1997 2,189.40 166.26 2,355.7

351716116363705 14N/3E-24Q5S 09/08/1997 2,189.00 166.74 2,355.7

351716116363705 14N/3E-24Q5S 07/08/1999 2,184.40 171.31 2,355.7

351716116363705 14N/3E-24Q5S 03/30/2000 2,181.10 174.64 2,355.7

351716116363705 14N/3E-24Q5S 01/30/2002 2,176.60 179.14 2,355.7

351716116363705 14N/3E-24Q5S 03/01/2005 2,166.00 189.73 2,355.7

351716116363705 14N/3E-24Q5S 11/06/2007 2,160.70 195.00 2,355.7

351716116363705 14N/3E-24Q5S 12/19/2007 2,160.40 195.25 2,355.7

351716116363705 14N/3E-24Q5S 02/14/2008 2,161.00 194.72 2,355.7

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
150 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA3-5—Continued

351716116363705 14N/3E-24Q5S 04/30/2008 2,161.60 194.13 2,355.7

351716116363705 14N/3E-24Q5S 07/28/2008 2,159.90 195.76 2,355.7

351716116363705 14N/3E-24Q5S 01/22/2009 2,159.40 196.31 2,355.7

351716116363705 14N/3E-24Q5S 01/26/2009 2,159.20 196.48 2,355.7

351716116363705 14N/3E-24Q5S 04/08/2009 2,158.20 197.47 2,355.7

351716116363705 14N/3E-24Q5S 10/07/2009 2,156.70 198.98 2,355.7

351716116363705 14N/3E-24Q5S 06/14/2010 2,157.30 198.41 2,355.7

351716116363705 14N/3E-24Q5S 12/17/2010 2,155.20 200.54 2,355.7

351716116363705 14N/3E-24Q5S 04/27/2011 2,154.00 201.68 2,355.7

351716116363705 14N/3E-24Q5S 10/24/2011 2,152.90 202.83 2,355.7

351716116363705 14N/3E-24Q5S 10/30/2011 2,153.00 202.69 2,355.7

351716116363705 14N/3E-24Q5S 02/13/2012 2,153.60 202.14 2,355.7

351716116363705 14N/3E-24Q5S 02/21/2012 2,153.30 202.37 2,355.7

351716116363705 14N/3E-24Q5S 08/30/2012 2,150.80 204.94 2,355.7

351716116363705 14N/3E-24Q5S 04/17/2013 2,151.20 204.47 2,355.7

351716116363705 14N/3E-24Q5S 09/10/2013 2,152.70 202.98 2,355.7

351716116363705 14N/3E-24Q5S 08/01/2014 2,150.40 205.32 2,355.7

351716116363705 14N/3E-24Q5S 11/04/2014 2,149.10 206.59 2,355.7

351716116363705 14N/3E-24Q5S 02/09/2015 2,150.30 205.37 2,355.7

351716116363705 14N/3E-24Q5S 02/16/2015 2,150.40 205.34 2,355.7

351716116363705 14N/3E-24Q5S 05/20/2015 2,150.00 205.69 2,355.7

Local ID: BLA5-1

351638116374301 14N/3E-26K1S 04/25/2011 2,160.00 185.15 2,345.0

351638116374301 14N/3E-26K1S 10/25/2011 2,159.00 186.08 2,345.0

351638116374301 14N/3E-26K1S 10/31/2011 2,159.00 186.24 2,345.0

351638116374301 14N/3E-26K1S 02/13/2012 2,158.00 186.54 2,345.0

351638116374301 14N/3E-26K1S 03/27/2012 2,158.00 187.01 2,345.0

351638116374301 14N/3E-26K1S 11/05/2014 2,154.00 190.94 2,345.0

351638116374301 14N/3E-26K1S 12/04/2014 2,154.00 190.97 2,345.0

351638116374301 14N/3E-26K1S 12/10/2014 2,154.00 190.90 2,345.0

351638116374301 14N/3E-26K1S 05/20/2015 2,153.00 191.54 2,345.0

351638116374301 14N/3E-26K1S 07/02/2015 2,153.00 191.90 2,345.0

Local ID: BLA5-3

351638116374303 14N/3E-26K3S 04/25/2011 2,161.00 184.20 2,345.0

351638116374303 14N/3E-26K3S 10/25/2011 2,160.00 185.08 2,345.0

351638116374303 14N/3E-26K3S 10/31/2011 2,160.00 185.26 2,345.0

351638116374303 14N/3E-26K3S 02/13/2012 2,159.00 185.64 2,345.0

351638116374303 14N/3E-26K3S 03/27/2012 2,159.00 186.17 2,345.0

351638116374303 14N/3E-26K3S 11/03/2014 2,155.00 189.92 2,345.0

351638116374303 14N/3E-26K3S 12/04/2014 2,155.00 189.97 2,345.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 151

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA5-3—Continued

351638116374303 14N/3E-26K3S 12/04/2014 2,143.00 201.53 2,345.0

351638116374303 14N/3E-26K3S 05/20/2015 2,154.00 190.70 2,345.0

351638116374303 14N/3E-26K3S 07/02/2015 2,154.00 190.91 2,345.0

Local ID: BLA5B-1

351638116374304 14N/3E-26K4S 04/25/2011 2,160.00 184.87 2,345.0

351638116374304 14N/3E-26K4S 10/25/2011 2,159.00 185.93 2,345.0

351638116374304 14N/3E-26K4S 10/31/2011 2,159.00 186.10 2,345.0

351638116374304 14N/3E-26K4S 02/13/2012 2,159.00 186.42 2,345.0

351638116374304 14N/3E-26K4S 03/27/2012 2,158.00 186.84 2,345.0

351638116374304 14N/3E-26K4S 11/05/2014 2,154.00 190.81 2,345.0

351638116374304 14N/3E-26K4S 12/04/2014 2,154.00 190.84 2,345.0

351638116374304 14N/3E-26K4S 05/20/2015 2,154.00 191.44 2,345.0

351638116374304 14N/3E-26K4S 07/02/2015 2,153.00 191.76 2,345.0

Local ID: BP-2, MW-12

351654116393301 14N/3E-27E1S 01/26/1993 2,325.80 75.60 2,401.4

351654116393301 14N/3E-27E1S 09/24/1993 2,321.10 80.29 2,401.4

351654116393301 14N/3E-27E1S 08/15/1994 2,325.00 76.38 2,401.4

351654116393301 14N/3E-27E1S 09/08/1994 2,324.50 76.88 2,401.4

351654116393301 14N/3E-27E1S 02/08/1995 2,326.10 75.27 2,401.4

351654116393301 14N/3E-27E1S 05/04/1995 2,327.90 73.50 2,401.4

351654116393301 14N/3E-27E1S 08/09/1995 2,327.70 73.68 2,401.4

351654116393301 14N/3E-27E1S 11/07/1995 2,327.40 73.96 2,401.4

Local ID: BP-3, MW-13

351656116393101 14N/3E-27E2S 01/26/1993 2,325.80 75.65 2,401.4

351656116393101 14N/3E-27E2S 09/23/1993 2,326.80 74.64 2,401.4

351656116393101 14N/3E-27E2S 08/15/1994 2,325.00 76.42 2,401.4

351656116393101 14N/3E-27E2S 09/08/1994 2,324.70 76.72 2,401.4

351656116393101 14N/3E-27E2S 02/08/1995 2,326.20 75.22 2,401.4

351656116393101 14N/3E-27E2S 05/04/1995 2,327.90 73.50 2,401.4

351656116393101 14N/3E-27E2S 08/09/1995 2,327.70 73.66 2,401.4

351656116393101 14N/3E-27E2S 11/07/1995 2,327.50 73.92 2,401.4

Local ID: BP-4, MW-14

351656116392901 14N/3E-27E3S 01/26/1993 2,324.90 76.48 2,401.4

351656116392901 14N/3E-27E3S 09/24/1993 2,320.40 81.00 2,401.4

351656116392901 14N/3E-27E3S 08/15/1994 2,324.20 77.15 2,401.4

351656116392901 14N/3E-27E3S 09/08/1994 2,324.10 77.33 2,401.4

351656116392901 14N/3E-27E3S 02/08/1995 2,325.40 76.00 2,401.4

351656116392901 14N/3E-27E3S 05/04/1995 2,326.90 74.54 2,401.4

351656116392901 14N/3E-27E3S 08/08/1995 2,327.00 74.43 2,401.4

351656116392901 14N/3E-27E3S 11/07/1995 2,326.70 74.66 2,401.4

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
152 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BP-4, MW-14—Continued

351656116392901 14N/3E-27E3S 01/30/2002 2,327.80 73.56 2,401.4

351656116392901 14N/3E-27E3S 03/01/2005 2,329.20 72.25 2,401.4

351656116392901 14N/3E-27E3S 11/06/2007 2,330.50 70.95 2,401.4

351656116392901 14N/3E-27E3S 12/18/2007 2,331.00 70.39 2,401.4

351656116392901 14N/3E-27E3S 02/16/2008 2,330.20 71.25 2,401.4

351656116392901 14N/3E-27E3S 04/30/2008 2,329.20 72.25 2,401.4

351656116392901 14N/3E-27E3S 07/29/2008 2,328.50 72.90 2,401.4

351656116392901 14N/3E-27E3S 01/22/2009 2,328.50 72.92 2,401.4

351656116392901 14N/3E-27E3S 01/27/2009 2,328.40 73.02 2,401.4

351656116392901 14N/3E-27E3S 04/07/2009 2,328.80 72.57 2,401.4

351656116392901 14N/3E-27E3S 06/15/2010 2,328.10 73.27 2,401.4

351656116392901 14N/3E-27E3S 12/14/2010 2,328.40 73.01 2,401.4

351656116392901 14N/3E-27E3S 12/14/2010 2,328.40 72.98 2,401.4

351656116392901 14N/3E-27E3S 10/25/2011 2,328.10 73.26 2,401.4

351656116392901 14N/3E-27E3S 02/13/2012 2,327.30 74.08 2,401.4

351656116392901 14N/3E-27E3S 02/21/2012 2,327.10 74.30 2,401.4

351656116392901 14N/3E-27E3S 08/30/2012 2,326.10 75.33 2,401.4

351656116392901 14N/3E-27E3S 04/17/2013 2,327.20 74.25 2,401.4

351656116392901 14N/3E-27E3S 09/10/2013 2,325.80 75.64 2,401.4

351656116392901 14N/3E-27E3S 08/01/2014 2,324.90 76.54 2,401.4

351656116392901 14N/3E-27E3S 05/20/2015 2,325.80 75.64 2,401.4

Local ID: BP-MW22

351659116393801 14N/3E-28A1S 09/24/1993 2,327.10 83.73 2,410.8

351659116393801 14N/3E-28A1S 02/09/1995 2,333.70 77.08 2,410.8

351659116393801 14N/3E-28A1S 05/05/1995 2,336.50 74.29 2,410.8

351659116393801 14N/3E-28A1S 08/09/1995 2,336.30 74.52 2,410.8

351659116393801 14N/3E-28A1S 11/08/1995 2,335.90 74.93 2,410.8

351659116393801 14N/3E-28A1S 07/01/1999 2,332.90 77.87 2,410.8

351659116393801 14N/3E-28A1S 07/28/2000 2,332.10 78.68 2,410.8

351659116393801 14N/3E-28A1S 01/30/2002 2,334.90 75.90 2,410.8

351659116393801 14N/3E-28A1S 03/01/2005 2,334.60 76.24 2,410.8

351659116393801 14N/3E-28A1S 11/06/2007 2,338.30 72.48 2,410.8

351659116393801 14N/3E-28A1S 02/16/2008 2,338.60 72.17 2,410.8

351659116393801 14N/3E-28A1S 04/29/2008 2,337.30 73.47 2,410.8

351659116393801 14N/3E-28A1S 07/29/2008 2,336.10 74.68 2,410.8

351659116393801 14N/3E-28A1S 01/22/2009 2,335.60 75.23 2,410.8

351659116393801 14N/3E-28A1S 04/08/2009 2,336.30 74.52 2,410.8

351659116393801 14N/3E-28A1S 12/14/2010 2,337.00 73.79 2,410.8

351659116393801 14N/3E-28A1S 10/25/2011 2,336.00 74.82 2,410.8

351659116393801 14N/3E-28A1S 02/13/2012 2,334.60 76.21 2,410.8

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 153

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BP-1, MW-11

351635116393601 14N/3E-28H1S 01/26/1993 2,330.70 76.67 2,407.4

351635116393601 14N/3E-28H1S 09/24/1993 2,332.60 74.80 2,407.4

351635116393601 14N/3E-28H1S 08/15/1994 2,330.20 77.19 2,407.4

351635116393601 14N/3E-28H1S 09/08/1994 2,330.10 77.27 2,407.4

351635116393601 14N/3E-28H1S 02/09/1995 2,334.00 73.42 2,407.4

351635116393601 14N/3E-28H1S 05/05/1995 2,336.80 70.64 2,407.4

351635116393601 14N/3E-28H1S 08/09/1995 2,336.40 71.03 2,407.4

351635116393601 14N/3E-28H1S 11/08/1995 2,335.80 71.64 2,407.4

Local ID: BP-MW21

351656116393401 14N/3E-28H2S 09/24/1993 2,329.10 71.79 2,400.9

351656116393401 14N/3E-28H2S 02/09/1995 2,330.70 70.21 2,400.9

351656116393401 14N/3E-28H2S 05/05/1995 2,334.70 66.16 2,400.9

351656116393401 14N/3E-28H2S 08/09/1995 2,332.60 68.34 2,400.9

351656116393401 14N/3E-28H2S 11/08/1995 2,332.10 68.80 2,400.9

Local ID: B-9_Aprt

351611116380201 14N/3E-35C1S 04/10/1963 2,225.00 127.00 2,352.0

351611116380201 14N/3E-35C1S 02/02/1993 2,331.00 21.15 2,352.0

351611116380201 14N/3E-35C1S 07/22/1994 2,209.00 143.05 2,352.0

351611116380201 14N/3E-35C1S 03/08/1995 2,202.00 149.69 2,352.0

351611116380201 14N/3E-35C1S 08/11/1995 2,203.00 148.79 2,352.0

351611116380201 14N/3E-35C1S 07/07/1999 2,194.00 158.31 2,352.0

351611116380201 14N/3E-35C1S 02/14/2008 2,172.00 179.55 2,352.0

351611116380201 14N/3E-35C1S 07/29/2008 2,165.00 186.95 2,352.0

Local ID: BLA1-1

351610116380201 14N/3E-35C2S 07/28/1994 2,207.73 149.67 2,357.4

351610116380201 14N/3E-35C2S 09/08/1994 2,207.42 149.98 2,357.4

351610116380201 14N/3E-35C2S 12/13/1994 2,207.50 149.90 2,357.4

351610116380201 14N/3E-35C2S 03/04/1995 2,207.27 150.13 2,357.4

351610116380201 14N/3E-35C2S 08/11/1995 2,205.00 152.40 2,357.4

351610116380201 14N/3E-35C2S 07/07/1999 2,199.34 158.06 2,357.4

351610116380201 14N/3E-35C2S 03/30/2000 2,197.72 159.68 2,357.4

351610116380201 14N/3E-35C2S 07/28/2000 2,195.21 162.19 2,357.4

351610116380201 14N/3E-35C2S 01/30/2002 2,193.01 164.39 2,357.4

351610116380201 14N/3E-35C2S 03/01/2005 2,183.69 173.71 2,357.4

Local ID: BLA1-2

351610116380501 14N/3E-35C4S 01/30/2002 2,189.32 162.68 2,352.0

351610116380501 14N/3E-35C4S 03/01/2005 2,180.16 171.84 2,352.0

351610116380501 14N/3E-35C4S 11/06/2007 2,176.16 175.84 2,352.0

351610116380501 14N/3E-35C4S 12/20/2007 2,175.87 176.13 2,352.0

351610116380501 14N/3E-35C4S 02/14/2008 2,176.03 175.97 2,352.0

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
154 Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: BLA1-2—Continued

351610116380501 14N/3E-35C4S 04/30/2008 2,175.65 176.35 2,352.0

351610116380501 14N/3E-35C4S 07/29/2008 2,174.37 177.63 2,352.0

351610116380501 14N/3E-35C4S 12/15/2010 2,170.57 181.43 2,352.0

351610116380501 14N/3E-35C4S 12/17/2010 2,170.49 181.51 2,352.0

351610116380501 14N/3E-35C4S 12/17/2010 2,170.49 181.51 2,352.0

351610116380501 14N/3E-35C4S 10/24/2011 2,169.14 182.86 2,352.0

351610116380501 14N/3E-35C4S 10/31/2011 2,169.10 182.90 2,352.0

351610116380501 14N/3E-35C4S 02/13/2012 2,168.99 183.01 2,352.0

351610116380501 14N/3E-35C4S 02/21/2012 2,168.82 183.18 2,352.0

351610116380501 14N/3E-35C4S 08/30/2012 2,167.60 184.40 2,352.0

351610116380501 14N/3E-35C4S 04/17/2013 2,167.34 184.66 2,352.0

351610116380501 14N/3E-35C4S 09/10/2013 2,166.96 185.04 2,352.0

351610116380501 14N/3E-35C4S 08/12/2014 2,166.16 185.84 2,352.0

351610116380501 14N/3E-35C4S 05/20/2015 2,165.00 186.73 2,352.0

Local ID: B-5

351811116361801 14N/4E-18N1S 01/26/1993 2,187.90 190.13 2,378.0

351811116361801 14N/4E-18N1S 07/21/1994 2,183.20 194.76 2,378.0

351811116361801 14N/4E-18N1S 12/20/1994 2,191.90 186.08 2,378.0

351811116361801 14N/4E-18N1S 03/01/2005 2,151.20 226.85 2,378.0

351811116361801 14N/4E-18N1S 10/27/2011 2,141.00 237.00 2,378.0

Local ID: B-5A

351811116361701 14N/4E-18N2S 12/03/1992 2,170.20 209.27 2,379.5

351811116361701 14N/4E-18N2S 01/26/1993 2,189.00 190.50 2,379.5

351811116361701 14N/4E-18N2S 09/07/1994 2,161.70 217.80 2,379.5

351811116361701 14N/4E-18N2S 11/22/1994 2,181.70 197.83 2,379.5

351811116361701 14N/4E-18N2S 03/03/1995 2,176.00 203.51 2,379.5

351811116361701 14N/4E-18N2S 08/03/1995 2,159.90 219.58 2,379.5

351811116361701 14N/4E-18N2S 09/18/1996 2,153.40 226.08 2,379.5

351811116361701 14N/4E-18N2S 07/08/1997 2,179.90 199.59 2,379.5

351811116361701 14N/4E-18N2S 09/03/1997 2,180.30 199.15 2,379.5

351811116361701 14N/4E-18N2S 09/08/1997 2,177.40 202.12 2,379.5

351811116361701 14N/4E-18N2S 07/09/1999 2,150.70 228.76 2,379.5

351811116361701 14N/4E-18N2S 03/30/2000 2,146.00 233.53 2,379.5

351811116361701 14N/4E-18N2S 07/28/2000 2,142.70 236.83 2,379.5

351811116361701 14N/4E-18N2S 01/30/2002 2,158.70 220.81 2,379.5

351811116361701 14N/4E-18N2S 03/01/2005 2,151.40 228.11 2,379.5

351811116361701 14N/4E-18N2S 11/06/2007 2,127.30 252.15 2,379.5

351811116361701 14N/4E-18N2S 12/19/2007 2,145.40 234.06 2,379.5

351811116361701 14N/4E-18N2S 02/14/2008 2,147.70 231.82 2,379.5

351811116361701 14N/4E-18N2S 04/29/2008 2,136.20 243.29 2,379.5

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]
Appendix 2 155

Site ID State 

well number

Date

(mm/dd/yyyy)

Water-surface altitude, 

feet above NAVD 88

Depth to water, 

feet below land surface

Land-surface altitude, 

feet above NAVD 88

Local ID: B-5A—Continued

351811116361701 14N/4E-18N2S 07/29/2008 2,127.40 252.14 2,379.5

351811116361701 14N/4E-18N2S 01/22/2009 2,128.90 250.55 2,379.5

351811116361701 14N/4E-18N2S 01/27/2009 2,128.30 251.21 2,379.5

351811116361701 14N/4E-18N2S 04/08/2009 2,126.00 253.54 2,379.5

351811116361701 14N/4E-18N2S 10/07/2009 2,124.20 255.33 2,379.5

351811116361701 14N/4E-18N2S 06/15/2010 2,127.40 252.11 2,379.5

351811116361701 14N/4E-18N2S 12/13/2010 2,124.70 254.85 2,379.5

351811116361701 14N/4E-18N2S 12/13/2010 2,124.70 254.83 2,379.5

351811116361701 14N/4E-18N2S 10/24/2011 2,139.60 239.93 2,379.5

351811116361701 14N/4E-18N2S 10/30/2011 2,140.10 239.41 2,379.5

351811116361701 14N/4E-18N2S 02/13/2012 2,126.50 252.97 2,379.5

351811116361701 14N/4E-18N2S 02/21/2012 2,138.50 241.03 2,379.5

351811116361701 14N/4E-18N2S 08/30/2012 2,119.30 260.23 2,379.5

351811116361701 14N/4E-18N2S 04/17/2013 2,140.90 238.59 2,379.5

351811116361701 14N/4E-18N2S 09/10/2013 2,144.30 235.20 2,379.5

351811116361701 14N/4E-18N2S 08/01/2014 2,120.10 259.37 2,379.5

351811116361701 14N/4E-18N2S 02/16/2015 2,123.20 256.33 2,379.5

351811116361701 14N/4E-18N2S 05/21/2015 2,139.20 240.26 2,379.5

Table 2–1. Water-level data for selected wells in Bicycle Basin, Fort Irwin National Training Center, California, 1955–2015.

—Continued

[State well number: See well-numbering system in text. Site identification (ID) is the latitude, longitude, and sequence number of the site. 

Abbreviations: mm/dd/yyyy, month/day/year; NAVD 88, North American Vertical Datum of 1988]

Appendix 3 157

Appendix 3. Water-Quality Data for Selected Wells in Bicycle Basin at Fort 

Irwin National Training Center, California, 1993–2011

Appendix 3
Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011. [E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data] State well number Date (mm/dd/yyyy) Site ID Local ID Time (hhmm) Depth of well, in ft below land surface (P72008) Depth to water level, in ft below land surface (P72019) Altitude of land surface, in feet (P72000) Carbon dioxide

water, unfiltered

milligrams per li

(P00405) 

14N/3E-13K1S 06/03/1993 351830116364501 B-1 1515 600 — 2,398 — 

14N/3E-13M1S 05/21/1993 351829116371201 B-4 0915 600 — 2,419 2.8 14N/3E-13M1S 06/03/1993 351829116371201 B-4 1510 600 — 2,419 — 

14N/3E-13M1S 09/14/1994 351829116371201 B-4 1015 600 — 2,419 4.4 14N/3E-13M2S 07/14/1997 351828116371201 BLA2 580-600 1200 600 319.95 2,418 5.7 14N/3E-13M2S 09/23/1997 351828116371201 BLA2 580-600 1430 600 — 2,418 3.3 14N/3E-13M2S 07/30/2000 351828116371201 BLA2 580-600 1200 600 — 2,418 2.8 14N/3E-13M3S 07/14/1997 351828116371202 BLA2 420-440 1700 440 301.07 2,418 13.0 14N/3E-13M3S 09/23/1997 351828116371202 BLA2 420-440 1800 440 — 2,418 16.0 14N/3E-13M3S 07/31/2000 351828116371202 BLA2 420-440 1145 440 — 2,418 3.9 

14N/3E-13M4S 09/24/1997 351828116371203 BLA2 310-330 1240 330 — 2,418 6.4 14N/3E-13M4S 07/30/2000 351828116371203 BLA2 310-330 1530 330 — 2,418 4.7 

14N/3E-13M4S 12/02/2010 351828116371203 BLA2 310-330 1314 330 — 2,418 3.2 

14N/3E-14H1S 06/03/1993 351830116372601 B-2 1500 602 — 2,423 — 

14N/3E-14H1S 07/29/1993 351830116372601 B-2 1030 602 — 2,423 3.3 

14N/3E-14P1S 03/28/2000 351810116375701 B-6 1230 535 — 2,380 3.5 

14N/3E-22N1S 05/19/1993 351710116392701 BA1 1830 260 170.96 2,418 2.7 14N/3E-22N1S 09/23/1993 351710116392701 BA1 1225 260 171.41 2,418 4.3 14N/3E-22N1S 09/21/1994 351710116392701 BA1 1300 260 171.56 2,418 5.7 14N/3E-22N1S 05/22/1996 351710116392701 BA1 1500 260 171.54 2,418 4.9 

14N/3E-22N1S 06/12/1996 351710116392701 BA1 1035 260 171.64 2,418 3.9 

14N/3E-22N1S 07/17/1997 351710116392701 BA1 1200 260 — 2,418 5.4 

14N/3E-23B1S 03/02/2010 351759116374401 BLA4-1 1530 850 — 2,375 1.3 

14N/3E-23B2S 03/02/2010 351759116374402 BLA4-2 1315 460 — 2,375 3.1 

14N/3E-23B2S 12/05/2011 351759116374402 BLA4-2 1635 460 — 2,375 3.0 

14N/3E-23B3S 03/02/2010 351759116374403 BLA4-3 1450 280 — 2,375 3.2 14N/3E-23B3S 12/05/2011 351759116374403 BLA4-3 1600 280 — 2,375 3.6 

14N/3E-23G1S 09/24/1993 351738116374101 BX-2 0930 747 146.47 2,361 2.7 14N/3E-23G1S 09/21/1994 351738116374101 BX-2 1730 747 147.36 2,361 3.0 14N/3E-23G1S 12/02/2010 351738116374101 BX-2 2100 747 — 2,361 2.7 
State well 

number

Date

(mm/dd/yyyy) Site ID Local ID Time (hhmm)

Depth of well, 

in ft below 

land surface

(P72008)

Depth to water 

level, in ft below 

land surface

(P72019)

Altitude of 

land surface, 

in feet

(P72000)

Carbon dioxide

water, unfiltered

milligrams per li

(P00405)

14N/3E-24H1S 07/29/1993 351742116362401 BX-1 1640 413 169.56 2,362 4.3 14N/3E-24H1S 09/20/1994 351742116362401 BX-1 1245 413 — 2,362 4.8 14N/3E-24Q1S 07/22/1997 351716116363701 BLA3 878-898 1400 898 — 2,356 4.8 14N/3E-24Q1S 09/08/1997 351716116363701 BLA3 878-898 1230 898 — 2,356 3.4 14N/3E-24Q1S 07/28/2000 351716116363701 BLA3 878-898 1330 898 — 2,356 3.4 14N/3E-24Q2S 07/23/1997 351716116363702 BLA3 725-734 1130 745 — 2,356 6.8 

14N/3E-24Q2S 09/09/1997 351716116363702 BLA3 725-734 1100 745 — 2,356 4.9 

14N/3E-24Q2S 07/29/2000 351716116363702 BLA3 725-734 1240 745 — 2,356 2.8 14N/3E-24Q3S 07/23/1997 351716116363703 BLA3 590-610 1700 610 — 2,356 13.0 14N/3E-24Q3S 09/10/1997 351716116363703 BLA3 590-610 1630 610 — 2,356 9.7 14N/3E-24Q3S 07/27/2000 351716116363703 BLA3 590-610 1645 610 — 2,356 3.8 14N/3E-24Q4S 07/24/1997 351716116363704 BLA3 430-450 1130 450 — 2,356 8.7 

14N/3E-24Q4S 09/10/1997 351716116363704 BLA3 430-450 1030 450 — 2,356 6.1 

14N/3E-24Q4S 07/29/2000 351716116363704 BLA3 430-450 1600 450 — 2,356 3.8 

14N/3E-24Q5S 07/24/1997 351716116363705 BLA3 290-310 1600 310 — 2,356 15.0 

14N/3E-24Q5S 09/08/1997 351716116363705 BLA3 290-310 1600 310 — 2,356 13.0 

14N/3E-24Q5S 07/28/2000 351716116363705 BLA3 290-310 1615 310 — 2,356 7.8 

14N/3E-24Q5S 12/06/2011 351716116363705 BLA3 290-310 1300 310 — 2,356 5.6 

14N/3E-26K1S 05/12/2011 351638116374301 BLA5 1 1250 360 — 2,343 0.9 

14N/3E-26K3S 12/08/2011 351638116374303 BLA5 3 1630 210 — 2,343 0.6 

14N/3E-26K4S 05/12/2011 351638116374304 BLA5B 1 1420 270 — 2,343 2.4 

14N/3E-27E1S 11/29/1994 351654116393301 BP-2, MW-12 1100 — — 2,399 5.5 

14N/3E-27E1S 02/08/1995 351654116393301 BP-2, MW-12 1600 — 75.27 2,399 3.2 

14N/3E-27E1S 05/04/1995 351654116393301 BP-2, MW-12 1640 — 73.50 2,399 2.6 

14N/3E-27E1S 05/08/1995 351654116393301 BP-2, MW-12 1800 — 73.50 2,399 3.0 14N/3E-27E1S 08/09/1995 351654116393301 BP-2, MW-12 1120 — 73.70 2,399 3.9 

14N/3E-27E1S 11/07/1995 351654116393301 BP-2, MW-12 1510 — 73.96 2,399 4.7 

14N/3E-27E2S 11/29/1994 351656116393101 BP-3, MW-13 1000 — — 2,399 3.1 

14N/3E-27E2S 02/08/1995 351656116393101 BP-3, MW-13 1330 — 75.22 2,399 3.1 

14N/3E-27E2S 05/04/1995 351656116393101 BP-3, MW-13 1400 — 73.50 2,399 2.3 

14N/3E-27E2S 08/09/1995 351656116393101 BP-3, MW-13 0920 — 73.70 2,399 2.6 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Site ID Local ID Time (hhmm) Depth of well, in ft below land surface (P72008) Depth to water level, in ft below land surface (P72019) Altitude of land surface, in feet (P72000) Carbon dioxide

water, unfiltered

milligrams per li

(P00405) 

14N/3E-27E2S 11/07/1995 351656116393101 BP-3, MW-13 1300 — 73.92 2,399 3.1 

14N/3E-27E3S 11/28/1994 351656116392901 BP-4, MW-14 1400 — — 2,399 1.5 

14N/3E-27E3S 02/08/1995 351656116392901 BP-4, MW-14 1000 — 76.00 2,399 1.4 

14N/3E-27E3S 05/04/1995 351656116392901 BP-4, MW-14 1345 — 74.50 2,399 1.5 

14N/3E-27E3S 08/08/1995 351656116392901 BP-4, MW-14 1930 — 74.40 2,399 1.5 

14N/3E-27E3S 11/07/1995 351656116392901 BP-4, MW-14 1045 — 74.66 2,399 2.3 

14N/3E-28A1S 11/29/1994 351659116393801 BP-MW22 1700 151.28 — 2,411 3.6 

14N/3E-28A1S 02/09/1995 351659116393801 BP-MW22 1515 151.28 77.08 2,411 3.7 

14N/3E-28A1S 05/05/1995 351659116393801 BP-MW22 1500 151.28 74.29 2,411 2.5 14N/3E-28A1S 08/09/1995 351659116393801 BP-MW22 1950 151.28 74.50 2,411 3.4 

14N/3E-28A1S 11/08/1995 351659116393801 BP-MW22 1520 151.28 74.93 2,411 3.3 

14N/3E-28H1S 11/29/1994 351635116393601 BP-1, MW-11 1440 — 75.57 2,405 11.0 

14N/3E-28H1S 02/09/1995 351635116393601 BP-1, MW-11 1230 — 73.42 2,405 14.0 

14N/3E-28H1S 05/05/1995 351635116393601 BP-1, MW-11 1140 — 70.64 2,405 5.1 

14N/3E-28H1S 08/09/1995 351635116393601 BP-1, MW-11 1420 — 71.00 2,405 8.6 

14N/3E-28H1S 11/08/1995 351635116393601 BP-1, MW-11 1320 — 71.64 2,405 8.5 

14N/3E-28H2S 11/29/1994 351656116393401 BP-MW21 1400 164.32 72.04 2,401 5.2 

14N/3E-28H2S 02/09/1995 351656116393401 BP-MW21 0945 164.32 70.21 2,401 3.8 

14N/3E-28H2S 05/05/1995 351656116393401 BP-MW21 1320 164.32 66.16 2,401 2.7 

14N/3E-28H2S 08/09/1995 351656116393401 BP-MW21 1220 164.32 68.30 2,401 4.2 

14N/3E-28H2S 11/08/1995 351656116393401 BP-MW21 1030 164.32 68.80 2,401 4.9 

14N/3E-35C1S 03/29/2000 351611116380201 AIRPORT 1215 245 — 2,350 1.7 

14N/3E-35C2S 07/31/2000 351610116380201 BLA1-1 1550 175 — 2,355 3.1 

14N/4E-18N1S 05/21/1993 351811116361801 B-5 0800 800 — 2,378 4.0 

14N/4E-18N1S 06/03/1993 351811116361801 B-5 1520 800 — 2,378 — 14N/4E-18N1S 09/23/1993 351811116361801 B-5 1000 800 — 2,378 6.5 

14N/4E-18N1S 09/14/1994 351811116361801 B-5 1430 800 — 2,378 7.7 

14N/4E-18N1S 03/28/2000 351811116361801 B-5 0915 800 — 2,378 3.7 

14N/4E-18N1S 12/09/2008 351811116361801 B-5 1350 800 — 2,378 5.4 

14N/4E-18N1S 12/01/2010 351811116361801 B-5 1130 800 — 2,378 3.0 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/[yyyy)

Specific conductance, 

lab, in microsiemens 

per centimeter at 

25 degrees Celsius

(P90095)

Specific conductance, 

in microsiemens 

per centimeter at 

25 degrees Celsius

(P00095)

Temperature, 

air, 

in degrees 

Celcius

(P00020)

Temperature, 

water, 

in degrees 

Celcius

(P00010)

Calcium, 

in milligrams 

per liter

(P00915)

Magnesium, 

in milligrams 

per liter

(P00925)

14N/3E-13K1S 06/03/1993 — — — — 36.0 7.10 

14N/3E-13M1S 05/21/1993 876 870 24.5 28.5 19.0 3.60 

14N/3E-13M1S 06/03/1993 — — — — 25.5 5.20 

14N/3E-13M1S 09/14/1994 877 882 — 27.5 19.0 3.70 

14N/3E-13M2S 07/14/1997 972 980 34.8 29.3 12.6 2.49 

14N/3E-13M2S 09/23/1997 935 977 33.8 28.5 14.0 2.82 

14N/3E-13M2S 07/30/2000 968 984 39.0 30.3 14.3 2.85 

14N/3E-13M3S 07/14/1997 904 908 36.9 29.2 12.8 3.75 

14N/3E-13M3S 09/23/1997 953 981 32.5 28.1 9.35 3.19 

14N/3E-13M3S 07/31/2000 838 857 — 29.3 23.0 4.53 

14N/3E-13M4S 09/24/1997 799 838 34.0 28.0 21.1 4.63 

14N/3E-13M4S 07/30/2000 923 942 41.5 30.7 29.4 5.82 

14N/3E-13M4S 12/02/2010 821 814 18.0 23.2 25.3 4.98 

14N/3E-14H1S 06/03/1993 — — — — 23.7 7.40 

14N/3E-14H1S 07/29/1993 871 888 — 29.0 20.0 3.70 

14N/3E-14P1S 03/28/2000 839 825 — 27.4 22.6 4.63 

14N/3E-22N1S 05/19/1993 939 946 29.0 27.0 17.0 6.70 

14N/3E-22N1S 09/23/1993 906 909 28.0 26.5 18.0 7.60 

14N/3E-22N1S 09/21/1994 901 931 — 29.0 19.0 7.60 

14N/3E-22N1S 05/22/1996 — 907 29.0 25.9 — — 

14N/3E-22N1S 06/12/1996 890 897 31.5 26.3 20.0 7.60 

14N/3E-22N1S 07/17/1997 874 884 — 27.9 18.7 7.10 

14N/3E-23B1S 03/02/2010 840 837 18.6 28.3 9.63 0.940 

14N/3E-23B2S 03/02/2010 1,840 1,890 19.1 27.3 20.4 4.45 

14N/3E-23B2S 12/05/2011 1,780 1,820 18.0 23.5 23.3 5.06 

14N/3E-23B3S 03/02/2010 868 864 18.4 23.6 18.9 3.29 

14N/3E-23B3S 12/05/2011 837 847 10.5 15.0 21.9 3.86 

14N/3E-23G1S 09/24/1993 880 872 — 24.5 18.0 3.30 

14N/3E-23G1S 09/21/1994 872 856 29.0 26.0 17.0 3.20 

14N/3E-23G1S 12/02/2010 1,200 1,200 7.0 22.0 11.2 1.79 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/[yyyy) Specific conductance, lab, in microsiemens per centimeter at 25 degrees Celsius (P90095) Specific conductance, in microsiemens per centimeter at 25 degrees Celsius (P00095) Temperature, air, in degrees Celcius (P00020) Temperature, water, in degrees Celcius (P00010) Calcium, in milligrams per liter (P00915) Magnesium, in milligrams per liter (P00925) 

14N/3E-24H1S 07/29/1993 820 838 34.5 24.5 31.0 10.0 

14N/3E-24H1S 09/20/1994 773 780 32.0 26.0 32.0 10.0 

14N/3E-24Q1S 07/22/1997 1,440 1,430 — 25.8 40.8 14.3 

14N/3E-24Q1S 09/08/1997 1,290 1,450 — 28.1 42.2 15.8 

14N/3E-24Q1S 07/28/2000 1,470 1,490 40.0 28.6 45.4 16.7 

14N/3E-24Q2S 07/23/1997 1,810 1,820 — 26.2 50.3 18.5 

14N/3E-24Q2S 09/09/1997 1,770 1,850 — 27.7 62.0 22.9 

14N/3E-24Q2S 07/29/2000 1,850 1,890 40.5 28.8 71.2 25.7 

14N/3E-24Q3S 07/23/1997 1,020 1,050 — 26.3 9.92 4.30 

14N/3E-24Q3S 09/10/1997 896 942 — 28.1 10.8 4.29 

14N/3E-24Q3S 07/27/2000 845 861 39.5 28.4 12.9 4.39 

14N/3E-24Q4S 07/24/1997 928 949 — 26.6 13.2 4.05 

14N/3E-24Q4S 09/10/1997 849 894 — 26.5 14.3 4.04 

14N/3E-24Q4S 07/29/2000 874 895 41.0 28.6 14.8 4.19 

14N/3E-24Q5S 07/24/1997 934 955 — 26.2 24.1 8.90 

14N/3E-24Q5S 09/08/1997 888 940 — 27.8 27.7 10.0 

14N/3E-24Q5S 07/28/2000 915 931 40.5 27.1 34.9 12.5 

14N/3E-24Q5S 12/06/2011 992 1,030 10.0 21.5 39.1 14.1 

14N/3E-26K1S 05/12/2011 810 837 27.5 25.0 5.62 1.46 

14N/3E-26K3S 12/08/2011 944 969 11.0 21.5 2.54 0.344 

14N/3E-26K4S 05/12/2011 759 781 29.5 24.5 18.1 4.36 

14N/3E-27E1S 11/29/1994 — 1,420 — 22.1 — — 14N/3E-27E1S 02/08/1995 — 1,420 15.5 21.3 — — 

14N/3E-27E1S 05/04/1995 — 1,450 22.8 22.7 — — 

14N/3E-27E1S 05/08/1995 1,450 1,440 23.1 22.7 86.0 12.0 

14N/3E-27E1S 08/09/1995 — 1,500 40.5 23.5 — — 

14N/3E-27E1S 11/07/1995 — 1,530 24.6 22.0 — — 14N/3E-27E2S 11/29/1994 — 1,440 — 22.2 — — 

14N/3E-27E2S 02/08/1995 — 1,440 16.2 21.9 — — 

14N/3E-27E2S 05/04/1995 — 1,470 24.6 23.3 — — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/[yyyy)

Specific conductance, 

lab, in microsiemens 

per centimeter at 

25 degrees Celsius

(P90095)

Specific conductance, 

in microsiemens 

per centimeter at 

25 degrees Celsius

(P00095)

Temperature, 

air, 

in degrees 

Celcius

(P00020)

Temperature, 

water, 

in degrees 

Celcius

(P00010)

Calcium, 

in milligrams 

per liter

(P00915)

Magnesium, 

in milligrams 

per liter

(P00925)

14N/3E-27E2S 08/09/1995 — 1,510 36.5 24.5 — — 

14N/3E-27E2S 11/07/1995 — 1,480 25.1 22.0 — — 14N/3E-27E3S 11/28/1994 — 1,120 — 22.0 — — 14N/3E-27E3S 02/08/1995 — 1,090 14.3 18.6 — — 

14N/3E-27E3S 05/04/1995 — 1,180 25.3 23.2 — — 

14N/3E-27E3S 08/08/1995 — 1,400 38.5 24.5 — — 

14N/3E-27E3S 11/07/1995 — 1,520 22.4 22.2 — — 14N/3E-28A1S 11/29/1994 — 1,470 — 21.6 — — 14N/3E-28A1S 02/09/1995 — 1,590 15.6 21.6 — — 

14N/3E-28A1S 05/05/1995 1,780 1,780 18.6 22.1 58.0 6.80 

14N/3E-28A1S 08/09/1995 — 1,840 37.0 24.0 — — 

14N/3E-28A1S 11/08/1995 1,780 1,740 26.5 22.4 53.0 6.40 

14N/3E-28H1S 11/29/1994 — 1,830 — 23.4 — — 14N/3E-28H1S 02/09/1995 — 1,620 16.8 22.0 — — 

14N/3E-28H1S 05/05/1995 — 1,490 17.0 20.8 — — 

14N/3E-28H1S 08/09/1995 — 1,550 43.3 24.5 — — 

14N/3E-28H1S 11/08/1995 — 1,560 24.0 22.0 — — 14N/3E-28H2S 11/29/1994 — 1,800 — 22.3 — — 14N/3E-28H2S 02/09/1995 — 1,700 16.3 21.5 — — 

14N/3E-28H2S 05/05/1995 — 1,630 17.5 22.7 — — 

14N/3E-28H2S 08/09/1995 — 1,810 42.0 24.5 — — 

14N/3E-28H2S 11/08/1995 — 1,800 23.2 22.0 — — 14N/3E-35C1S 03/29/2000 1,010 986 — 22.8 8.89 3.18 

14N/3E-35C2S 07/31/2000 1,040 1,060 39.5 27.8 9.35 3.67 

14N/4E-18N1S 05/21/1993 1,210 1,210 19.5 24.5 58.0 10.0 

14N/4E-18N1S 06/03/1993 — — — — 70.5 11.7 

14N/4E-18N1S 09/23/1993 1,180 1,190 21.0 27.5 61.0 10.0 

14N/4E-18N1S 09/14/1994 1,190 1,200 — 27.5 57.0 9.90 

14N/4E-18N1S 03/28/2000 1,180 1,170 — 25.6 55.8 10.0 

14N/4E-18N1S 12/09/2008 1,340 1,370 13.0 28.0 67.4 10.7 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/[yyyy) Specific conductance, lab, in microsiemens per centimeter at 25 degrees Celsius (P90095) Specific conductance, in microsiemens per centimeter at 25 degrees Celsius (P00095) Temperature, air, in degrees Celcius (P00020) Temperature, water, in degrees Celcius (P00010) Calcium, in milligrams per liter (P00915) Magnesium, in milligrams per liter (P00925) 

14N/4E-18N1S 12/01/2010 1,340 1,320 8.0 27.0 64.7 10.5 

State well number Date (mm/dd/yyyy) Alkalinity, fixed endpoint (pH 4.5) titration, field, in milligrams per liter as calcium carbonate (P39036) Alkalinity, fixed endpoint (pH 4.5) titration, laboratory, in milligrams per liter as calcium carbonate (P90410) Alkalinity, inflection- point titration method (incremental titration method), field, in milligrams per liter as calcium carbonate (P29801) Bromide, in milligrams per liter (P71870) Chloride, in milligrams per liter (P00940) Fluoride, in milligrams per liter (P00950) Iodide

in milligram

per lite

(P71865

14N/3E-13K1S 06/03/1993 — 153 — — 78.6 1.90 — 

14N/3E-13M1S 05/21/1993 160 — 164 0.350 80.0 2.50 0.034 

14N/3E-13M1S 06/03/1993 — 111 — — 103 2.50 — 14N/3E-13M1S 09/14/1994 140 — 142 0.340 80.0 2.70 0.037 

14N/3E-13M2S 07/14/1997 180 — — 0.370 82.2 3.48 0.042 

14N/3E-13M2S 09/23/1997 170 — — 0.360 79.5 3.21 0.053 

14N/3E-13M2S 07/30/2000 — 184 — 0.360 80.6 3.53 0.026 

14N/3E-13M3S 07/14/1997 160 — 166 0.320 73.9 2.23 0.053 

14N/3E-13M3S 09/23/1997 190 — — 0.320 67.7 1.54 0.054 

14N/3E-13M3S 07/31/2000 — 159 — 0.320 70.4 1.83 0.033 

14N/3E-13M4S 09/24/1997 — 160 — 0.310 60.6 2.09 0.031 

14N/3E-13M4S 07/30/2000 — 153 — 0.350 101 1.84 0.037 

14N/3E-13M4S 12/02/2010 150 159 144 0.380 63.1 0.19 0.006 

14N/3E-14H1S 06/03/1993 — 170 — — 71.7 2.70 — 

14N/3E-14H1S 07/29/1993 170 — 172 0.330 69.0 2.40 0.023 

14N/3E-14P1S 03/28/2000 140 21.0 144 0.330 65.3 3.50 0.018 

14N/3E-22N1S 05/19/1993 180 182 — 0.270 74.0 3.20 0.084 

14N/3E-22N1S 09/23/1993 170 — 172 0.290 70.0 3.00 0.078 

14N/3E-22N1S 09/21/1994 170 — 177 0.280 64.0 2.70 0.074 

14N/3E-22N1S 05/22/1996 180 — — — — — — 

14N/3E-22N1S 06/12/1996 170 — — 0.250 60.0 2.60 0.078 

14N/3E-22N1S 07/17/1997 180 — 181 0.230 60.4 2.60 0.085 

14N/3E-23B1S 03/02/2010 140 160 142 0.350 73.5 3.18 0.070 

14N/3E-23B2S 03/02/2010 180 194 175 0.880 307 7.25 0.149 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Alkalinity, fixed 

endpoint (pH 4.5) 

titration, field, 

in milligrams 

per liter as 

calcium carbonate

(P39036)

Alkalinity, fixed 

endpoint (pH 4.5) 

titration, laboratory, 

in milligrams 

per liter as 

calcium carbonate

(P90410)

Alkalinity, inflectionpoint titration method 

(incremental titration 

method), field, 

in milligrams per liter as 

calcium carbonate

(P29801)

Bromide, 

in 

milligrams 

per liter

(P71870)

Chloride, 

in 

milligrams 

per liter

(P00940)

Fluoride, 

in 

milligrams 

per liter

(P00950)

Iodide

in 

milligram

per lite

(P71865

14N/3E-23B2S 12/05/2011 — 191 — 0.786 300 7.81 0.139 

14N/3E-23B3S 03/02/2010 170 178 169 0.310 68.4 3.41 0.018 

14N/3E-23B3S 12/05/2011 — 178 — 0.296 67.1 3.52 0.007 

14N/3E-23G1S 09/24/1993 160 — 158 0.310 70.0 5.80 0.045 

14N/3E-23G1S 09/21/1994 170 — 172 0.320 67.0 6.00 0.028 

14N/3E-23G1S 12/02/2010 180 192 182 0.490 145 5.74 0.372 

14N/3E-24H1S 07/29/1993 140 — 141 0.350 94.0 2.00 0.012 

14N/3E-24H1S 09/20/1994 140 — 139 0.300 84.0 1.90 0.011 

14N/3E-24Q1S 07/22/1997 110 — 110 0.690 270 1.55 0.055 14N/3E-24Q1S 09/08/1997 110 — 108 0.660 294 1.35 0.053 14N/3E-24Q1S 07/28/2000 — 112 — 0.740 294 1.23 0.023 14N/3E-24Q2S 07/23/1997 100 — 101 0.900 371 1.37 0.059 

14N/3E-24Q2S 09/09/1997 95 — 94 0.910 408 1.13 0.048 

14N/3E-24Q2S 07/29/2000 — 92.0 — 0.910 396 1.26 0.034 

14N/3E-24Q3S 07/23/1997 200 — 204 0.360 116 2.57 0.046 14N/3E-24Q3S 09/10/1997 190 — 190 0.350 127 2.46 0.053 

14N/3E-24Q3S 07/27/2000 — 195 — 0.290 105 2.30 0.025 

14N/3E-24Q4S 07/24/1997 200 — 196 0.310 78.6 2.10 0.045 

14N/3E-24Q4S 09/10/1997 190 — 190 0.310 71.6 2.10 0.044 

14N/3E-24Q4S 07/29/2000 — 196 — 0.320 69.0 2.62 0.031 

14N/3E-24Q5S 07/24/1997 190 — 194 0.310 75.3 1.59 0.047 

14N/3E-24Q5S 09/08/1997 200 — 198 0.350 75.7 1.70 0.035 

14N/3E-24Q5S 07/28/2000 — 201 — 0.360 76.8 1.64 0.020 

14N/3E-24Q5S 12/06/2011 180 193 178 0.431 124 1.92 0.005 

14N/3E-26K1S 05/12/2011 160 169 — 0.328 67.4 2.97 0.008 

14N/3E-26K3S 12/08/2011 250 251 248 0.317 62.4 4.30 0.010 

14N/3E-26K4S 05/12/2011 140 151 — 0.324 64.5 3.06 0.005 

14N/3E-27E1S 11/29/1994 91 — 93 — — — — 

14N/3E-27E1S 02/08/1995 90 — 90 — — — — 

14N/3E-27E1S 05/04/1995 84 — 84 — — — — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Alkalinity, fixed endpoint (pH 4.5) titration, field, in milligrams per liter as calcium carbonate (P39036) Alkalinity, fixed endpoint (pH 4.5) titration, laboratory, in milligrams per liter as calcium carbonate (P90410) Alkalinity, inflection- point titration method (incremental titration method), field, in milligrams per liter as calcium carbonate (P29801) Bromide, in milligrams per liter (P71870) Chloride, in milligrams per liter (P00940) Fluoride, in milligrams per liter (P00950) Iodide

in milligram

per lite

(P71865

14N/3E-27E1S 05/08/1995 84 — 84 — 220 2.40 — 14N/3E-27E1S 08/09/1995 85 — 86 — — — — 

14N/3E-27E1S 11/07/1995 83 — 83 — — — — 

14N/3E-27E2S 11/29/1994 87 — 87 — — — — 

14N/3E-27E2S 02/08/1995 93 — 95 — — — — 

14N/3E-27E2S 05/04/1995 81 — 81 — — — — 

14N/3E-27E2S 08/09/1995 80 — 80 — — — — 

14N/3E-27E2S 11/07/1995 74 — 74 — — — — 

14N/3E-27E3S 11/28/1994 95 — 94 — — — — 

14N/3E-27E3S 02/08/1995 97 — 94 — — — — 

14N/3E-27E3S 05/04/1995 89 — 89 — — — — 

14N/3E-27E3S 08/08/1995 83 — 84 — — — — 

14N/3E-27E3S 11/07/1995 78 — 80 — — — — 

14N/3E-28A1S 11/29/1994 120 — 119 — — — — 

14N/3E-28A1S 02/09/1995 110 — 111 — — — — 

14N/3E-28A1S 05/05/1995 100 — 101 — 280 3.20 — 

14N/3E-28A1S 08/09/1995 98 — 99 — — — — 

14N/3E-28A1S 11/08/1995 97 — 99 — 270 4.20 — 14N/3E-28H1S 11/29/1994 140 — 138 — — — — 

14N/3E-28H1S 02/09/1995 130 — 131 — — — — 

14N/3E-28H1S 05/05/1995 130 — 132 — — — — 

14N/3E-28H1S 08/09/1995 130 — 134 — — — — 

14N/3E-28H1S 11/08/1995 130 — 128 — — — — 

14N/3E-28H2S 11/29/1994 98 — 96 — — — — 

14N/3E-28H2S 02/09/1995 91 — 92 — — — — 

14N/3E-28H2S 05/05/1995 89 — 88 — — — — 

14N/3E-28H2S 08/09/1995 88 — 89 — — — — 

14N/3E-28H2S 11/08/1995 87 — 88 — — — — 

14N/3E-35C1S 03/29/2000 220 154 219 0.090 70.7 5.37 0.024 

14N/3E-35C2S 07/31/2000 — 259 — 0.290 63.7 5.16 0.035 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Alkalinity, fixed 

endpoint (pH 4.5) 

titration, field, 

in milligrams 

per liter as 

calcium carbonate

(P39036)

Alkalinity, fixed 

endpoint (pH 4.5) 

titration, laboratory, 

in milligrams 

per liter as 

calcium carbonate

(P90410)

Alkalinity, inflectionpoint titration method 

(incremental titration 

method), field, 

in milligrams per liter as 

calcium carbonate

(P29801)

Bromide, 

in 

milligrams 

per liter

(P71870)

Chloride, 

in 

milligrams 

per liter

(P00940)

Fluoride, 

in 

milligrams 

per liter

(P00950)

Iodide

in 

milligram

per lite

(P71865

14N/4E-18N1S 05/21/1993 120 — 124 0.490 200 1.10 0.019 

14N/4E-18N1S 06/03/1993 — 114 — — 228 1.50 — 14N/4E-18N1S 09/23/1993 120 — 118 0.590 200 1.20 0.016 

14N/4E-18N1S 09/14/1994 120 — 122 0.510 200 1.20 0.022 

14N/4E-18N1S 03/28/2000 120 231 119 0.460 193 1.20 0.013 

14N/4E-18N1S 12/09/2008 — 118 — 0.250 248 1.00 0.007 14N/4E-18N1S 12/01/2010 110 120 113 0.670 245 0.96 0.003 

State well 

number

Date

(mm/dd/yyyy)

Dissolved solids, 

sum of constituents, 

in milligrams 

per liter

(P70301)

Ammonia, 

in milligrams 

per liter 

as nitrogen

(P00608)

Nitrate plus nitrite, 

in milligrams 

per liter as 

nitrogen

(P00631)

Nitrate, 

in milligrams 

per liter as 

nitrogen

(P00618)

Nitrite, 

in milligrams 

per liter as 

nitrogen

(P00613)

Organic 

nitrogen, in 

milligrams 

per liter 

(P00607)

Total 

nitrogen, in 

milligrams 

per liter 

(P00602)

Or

phos

in mi

pe

(P0

14N/3E-13K1S 06/03/1993 480 <0.020 4.70 — — — — 14N/3E-13M1S 05/21/1993 601 <0.020 4.80 — <0.010 — — 

14N/3E-13M1S 06/03/1993 510 0.010 5.80 — — — — 14N/3E-13M1S 09/14/1994 592 <0.020 5.00 — <0.010 — — 

14N/3E-13M2S 07/14/1997 669 <0.020 3.14 3.12 0.019 — — 114N/3E-13M2S 09/23/1997 677 0.020 3.11 — <0.010 — — 014N/3E-13M2S 07/30/2000 655 <0.020 3.27 — <0.010 — — 0

14N/3E-13M3S 07/14/1997 630 <0.010 4.55 4.39 0.160 — — 7

14N/3E-13M3S 09/23/1997 711 <0.010 5.15 — <0.010 — — 57

14N/3E-13M3S 07/31/2000 574 <0.010 3.79 — <0.010 — — 0

14N/3E-13M4S 09/24/1997 594 <0.010 6.16 — <0.010 — — 5

14N/3E-13M4S 07/30/2000 618 <0.020 4.66 — <0.010 — — 0

14N/3E-13M4S 12/02/2010 572 <0.020 6.08 6.08 <0.001 <0.05 <6.1 0

14N/3E-14H1S 06/03/1993 521 0.015 4.20 — — — — 14N/3E-14H1S 07/29/1993 584 <0.020 5.00 — <0.010 — — 

14N/3E-14P1S 03/28/2000 579 <0.020 5.87 — <0.010 — — 

14N/3E-22N1S 05/19/1993 577 <0.010 1.20 1.18 0.020 — — 0

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Dissolved solids, sum of constituents, in milligrams per liter (P70301) Ammonia, in milligrams per liter as nitrogen (P00608) Nitrate plus nitrite, in milligrams per liter as nitrogen (P00631) Nitrate, in milligrams per liter as nitrogen (P00618) Nitrite, in milligrams per liter as nitrogen (P00613) Organic nitrogen, in milligrams per liter (P00607) Total nitrogen, in milligrams per liter (P00602) Or

phos

in mi

pe

(P0

14N/3E-22N1S 09/23/1993 561 <0.020 1.10 1.09 0.010 — — 014N/3E-22N1S 09/21/1994 553 <0.020 0.98 0.95 0.030 — — 314N/3E-22N1S 05/22/1996 — — — — — — — 14N/3E-22N1S 06/12/1996 544 <0.020 1.10 1.08 0.020 — — 214N/3E-22N1S 07/17/1997 541 <0.010 1.09 1.07 0.022 — — 114N/3E-23B1S 03/02/2010 E583 <0.020 1.74 1.71 0.029 — — 014N/3E-23B2S 03/02/2010 E1,130 <0.020 0.98 0.91 0.068 — — 0

14N/3E-23B2S 12/05/2011 1,130 <0.020 1.10 1.02 0.085 <0.16 <1.2 0

14N/3E-23B3S 03/02/2010 E575 <0.020 5.29 — <0.002 — E5.4 0

14N/3E-23B3S 12/05/2011 601 <0.010 5.30 5.29 0.004 <0.26 <5.4 0

14N/3E-23G1S 09/24/1993 603 <0.020 8.70 — <0.010 — — 0

14N/3E-23G1S 09/21/1994 606 <0.020 8.40 — <0.010 — — 

14N/3E-23G1S 12/02/2010 789 <0.020 6.71 6.71 <0.001 <0.07 6.8 0

14N/3E-24H1S 07/29/1993 529 <0.020 7.00 — <0.010 — — 

14N/3E-24H1S 09/20/1994 498 0.010 7.50 — <0.010 — — 

14N/3E-24Q1S 07/22/1997 799 <0.020 3.91 3.77 0.147 — — 1

14N/3E-24Q1S 09/08/1997 836 <0.020 3.63 3.54 0.081 — — 1

14N/3E-24Q1S 07/28/2000 E822 <0.020 3.43 — <0.010 — — 0

14N/3E-24Q2S 07/23/1997 1,020 <0.020 4.38 4.12 0.267 — — 6

14N/3E-24Q2S 09/09/1997 1,050 0.020 4.47 4.46 0.014 — — 214N/3E-24Q2S 07/29/2000 E1,030 0.020 4.39 — <0.010 — — 014N/3E-24Q3S 07/23/1997 628 <0.010 3.56 3.16 0.402 — — 1414N/3E-24Q3S 09/10/1997 561 — 2.04 2.02 0.017 — — 10

14N/3E-24Q3S 07/27/2000 E499 0.040 1.76 — <0.010 — — 114N/3E-24Q4S 07/24/1997 599 <0.020 6.04 5.89 0.154 — — 614N/3E-24Q4S 09/10/1997 569 <0.020 5.63 5.62 0.012 — — 314N/3E-24Q4S 07/29/2000 557 0.020 5.51 — <0.010 — — 014N/3E-24Q5S 07/24/1997 601 <0.020 5.39 5.35 0.045 — — 414N/3E-24Q5S 09/08/1997 614 0.040 5.72 — <0.010 — — 814N/3E-24Q5S 07/28/2000 590 <0.020 5.30 — <0.010 — — 014N/3E-24Q5S 12/06/2011 636 <0.020 5.10 5.10 <0.001 <0.31 <5.2 0

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Dissolved solids, 

sum of constituents, 

in milligrams 

per liter

(P70301)

Ammonia, 

in milligrams 

per liter 

as nitrogen

(P00608)

Nitrate plus nitrite, 

in milligrams 

per liter as 

nitrogen

(P00631)

Nitrate, 

in milligrams 

per liter as 

nitrogen

(P00618)

Nitrite, 

in milligrams 

per liter as 

nitrogen

(P00613)

Organic 

nitrogen, in 

milligrams 

per liter 

(P00607)

Total 

nitrogen, in 

milligrams 

per liter 

(P00602)

Or

phos

in mi

pe

(P0

14N/3E-26K1S 05/12/2011 551 0.020 4.64 4.63 0.004 <0.07 4.7 0

14N/3E-26K3S 12/08/2011 645 <0.020 5.26 5.26 0.002 — <5.3 0

14N/3E-26K4S 05/12/2011 545 <0.020 4.67 4.66 0.003 <0.06 4.7 0

14N/3E-27E1S 11/29/1994 — <0.020 19.0 19.0 0.010 — — 

14N/3E-27E1S 02/08/1995 — <0.020 20.0 20.0 0.030 — — 

14N/3E-27E1S 05/04/1995 — <0.020 20.0 — <0.010 — — 

14N/3E-27E1S 05/08/1995 879 <0.020 20.0 20.0 0.010 0.18 20.0 0

14N/3E-27E1S 08/09/1995 — <0.020 22.0 — <0.010 — — 0

14N/3E-27E1S 11/07/1995 — <0.020 22.0 — <0.010 — — 0

14N/3E-27E2S 11/29/1994 — <0.010 20.0 — <0.010 — — 

14N/3E-27E2S 02/08/1995 — <0.010 21.0 21.0 0.020 — — 0

14N/3E-27E2S 05/04/1995 — 0.010 21.0 — <0.010 — — 0

14N/3E-27E2S 08/09/1995 — <0.010 22.0 — <0.010 — — 0

14N/3E-27E2S 11/07/1995 — <0.010 20.0 — <0.010 — — 0

14N/3E-27E3S 11/28/1994 — <0.010 25.0 — <0.010 — — 0

14N/3E-27E3S 02/08/1995 — <0.020 14.0 14.0 0.020 — — 0

14N/3E-27E3S 05/04/1995 — <0.020 15.0 — <0.010 — — 

14N/3E-27E3S 08/08/1995 — <0.010 19.0 — <0.010 — — 

14N/3E-27E3S 11/07/1995 — <0.020 22.0 — <0.010 — — 

14N/3E-28A1S 11/29/1994 — <0.010 21.0 21.0 0.010 0.19 21.0 0

14N/3E-28A1S 02/09/1995 — <0.020 23.0 23.0 0.020 — — 014N/3E-28A1S 05/05/1995 1,080 0.020 30.0 — <0.010 — — 014N/3E-28A1S 08/09/1995 — — 31.0 — <0.010 — — 

14N/3E-28A1S 11/08/1995 1,060 0.010 30.0 — <0.010 — — 

14N/3E-28H1S 11/29/1994 — <0.010 20.0 — <0.010 — — 

14N/3E-28H1S 02/09/1995 — <0.020 16.0 — <0.010 — — 014N/3E-28H1S 05/05/1995 — <0.020 13.0 — <0.010 — — 

14N/3E-28H1S 08/09/1995 — — 14.0 — <0.010 — — 014N/3E-28H1S 11/08/1995 — <0.010 14.0 — <0.010 — — 0

14N/3E-28H2S 11/29/1994 — <0.020 26.0 — <0.010 — — 

14N/3E-28H2S 02/09/1995 — <0.020 23.0 — <0.010 — — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Dissolved solids, sum of constituents, in milligrams per liter (P70301) Ammonia, in milligrams per liter as nitrogen (P00608) Nitrate plus nitrite, in milligrams per liter as nitrogen (P00631) Nitrate, in milligrams per liter as nitrogen (P00618) Nitrite, in milligrams per liter as nitrogen (P00613) Organic nitrogen, in milligrams per liter (P00607) Total nitrogen, in milligrams per liter (P00602) Or

phos

in mi

pe

(P0

14N/3E-28H2S 05/05/1995 — <0.020 21.0 — <0.010 — — 

14N/3E-28H2S 08/09/1995 — <0.020 21.0 — <0.010 — — 

14N/3E-28H2S 11/08/1995 — <0.020 23.0 — <0.010 — — 

14N/3E-35C1S 03/29/2000 637 <0.020 7.04 — <0.010 — — 014N/3E-35C2S 07/31/2000 E654 <0.020 4.25 — <0.010 — — 014N/4E-18N1S 05/21/1993 727 <0.020 5.40 — <0.010 — — 

14N/4E-18N1S 06/03/1993 758 <0.010 5.60 — — — — 

14N/4E-18N1S 09/23/1993 719 0.010 5.30 — <0.010 — — 0

14N/4E-18N1S 09/14/1994 717 — 5.60 — <0.010 — — 

14N/4E-18N1S 03/28/2000 706 <0.010 5.53 — <0.010 — — 

14N/4E-18N1S 12/09/2008 798 — 4.94 — <0.002 — — 0

14N/4E-18N1S 12/01/2010 786 <0.010 4.96 4.96 <0.001 <0.06 5.0 0

State well number Date (mm/dd/yyyy) Phosphorus, milligrams per liter as phosphorus (P00666) Aluminum, micrograms per liter (P01106) Arsenic, micrograms per liter (P01000) Barium, micrograms per liter (P01005) Boron, micrograms per liter (P01020) Chromium, micrograms per liter (P01030) Iron, micrograms per liter (P01046) Lithium, micrograms per liter (P01130) 

14N/3E-13K1S 06/03/1993 — — — — — — — — 14N/3E-13M1S 05/21/1993 <0.01 <10.0 29.0 36.0 1,200 — 9.0 48.0 

14N/3E-13M1S 06/03/1993 — — — — — — — — 14N/3E-13M1S 09/14/1994 0.01 — 37.0 36.0 1,200 — <3.0 49.0 

14N/3E-13M2S 07/14/1997 1.58 — 35.0 26.5 1,130 — 7.0 — 

14N/3E-13M2S 09/23/1997 0.21 — 39.0 34.0 1,190 — <3.0 — 

14N/3E-13M2S 07/30/2000 <0.05 <20.0 41.7 35.2 1,110 — <10.0 42.0 14N/3E-13M3S 07/14/1997 7.95 — 45.0 9.0 1,130 — 179.0 — 

14N/3E-13M3S 09/23/1997 21.0 — 72.0 10.2 1,220 — 122 — 

14N/3E-13M3S 07/31/2000 E0.04 <20.0 36.1 32.1 1,110 — <10.0 44.0 

14N/3E-13M4S 09/24/1997 2.95 — 29.0 25.5 1,260 — 41.0 — 

14N/3E-13M4S 07/30/2000 E0.04 <20.0 24.6 39.1 1,210 — <10.0 58.0 

14N/3E-13M4S 12/02/2010 <0.02 <5.1 24.6 31.9 1,110 — <3.0 73.0 

14N/3E-14H1S 06/03/1993 — — — — — — — — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Phosphorus, 

milligrams per liter 

as phosphorus

(P00666)

Aluminum, 

micrograms 

per liter

(P01106)

Arsenic, 

micrograms 

per liter

(P01000)

Barium, 

micrograms 

per liter

(P01005)

Boron, 

micrograms 

per liter

(P01020)

Chromium, 

micrograms 

per liter

(P01030)

Iron, 

micrograms 

per liter

(P01046)

Lithium, 

micrograms 

per liter

(P01130)

14N/3E-14H1S 07/29/1993 <0.01 4.0 29.0 35.0 1,200 10.0 8.0 50.0 

14N/3E-14P1S 03/28/2000 <0.05 <20.0 19.0 32.2 1,110 — <10.0 45.0 14N/3E-22N1S 05/19/1993 0.17 — 3.0 8.0 1,000 — 7.0 31.0 

14N/3E-22N1S 09/23/1993 0.23 12.0 3.0 9.0 1,100 <1.00 <3.0 30.0 

14N/3E-22N1S 09/21/1994 1.30 — 7.0 8.0 1,000 — <3.0 31.0 

14N/3E-22N1S 05/22/1996 — — — — — — — — 14N/3E-22N1S 06/12/1996 0.81 — 4.0 <100 1,040 — <3.0 28.0 

14N/3E-22N1S 07/17/1997 0.33 — 3.0 8.5 994 — <3.0 — 

14N/3E-23B1S 03/02/2010 <0.04 E7.7 103 30.3 1,040 5.10 <6.0 45.0 

14N/3E-23B2S 03/02/2010 0.09 E2.4 45.7 23.8 1,230 E0.11 <6.0 44.0 

14N/3E-23B2S 12/05/2011 0.06 <11.0 39.2 25.4 1,310 — 14.2 47.5 

14N/3E-23B3S 03/02/2010 E0.02 E6.8 73.7 29.3 1,090 41.0 <6.0 80.0 

14N/3E-23B3S 12/05/2011 0.03 6.8 24.4 30.1 1,160 — 4.7 89.0 

14N/3E-23G1S 09/24/1993 0.05 17.0 22.0 33.0 1,200 11.0 24.0 60.0 

14N/3E-23G1S 09/21/1994 <0.01 — 24.0 29.0 1,200 — <3.0 53.0 

14N/3E-23G1S 12/02/2010 <0.02 4.0 21.3 12.5 1,370 — <3.0 71.0 

14N/3E-24H1S 07/29/1993 <0.01 3.0 6.0 44.0 860 4.00 12.0 30.0 

14N/3E-24H1S 09/20/1994 <0.01 — 7.0 42.0 780 — 25.0 35.0 

14N/3E-24Q1S 07/22/1997 1.20 — 5.0 15.6 794 — <3.0 — 

14N/3E-24Q1S 09/08/1997 0.38 — 3.0 14.9 808 — <3.0 — 

14N/3E-24Q1S 07/28/2000 0.06 E10.0 E1.0 12.8 777 — <10.0 35.0 

14N/3E-24Q2S 07/23/1997 2.95 — 6.0 15.6 792 — 5.0 — 

14N/3E-24Q2S 09/09/1997 0.76 — 2.0 19.5 745 — 5.0 — 

14N/3E-24Q2S 07/29/2000 <0.05 <20.0 E0.5 16.8 726 — <10.0 43.0 

14N/3E-24Q3S 07/23/1997 9.88 — 13.0 3.0 934 — 148 — 

14N/3E-24Q3S 09/10/1997 6.08 — 8.0 4.6 896 — 74.0 — 

14N/3E-24Q3S 07/27/2000 0.51 <20.0 2.7 9.3 846 — <10.0 21.0 

14N/3E-24Q4S 07/24/1997 4.18 — 21.0 6.8 924 — 67.0 — 

14N/3E-24Q4S 09/10/1997 1.44 — 12.0 10.4 919 — <3.0 — 

14N/3E-24Q4S 07/29/2000 <0.05 <20.0 6.7 13.3 889 — <10.0 27.0 

14N/3E-24Q5S 07/24/1997 4.71 — 11.0 6.7 876 — 138 — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Phosphorus, milligrams per liter as phosphorus (P00666) Aluminum, micrograms per liter (P01106) Arsenic, micrograms per liter (P01000) Barium, micrograms per liter (P01005) Boron, micrograms per liter (P01020) Chromium, micrograms per liter (P01030) Iron, micrograms per liter (P01046) Lithium, micrograms per liter (P01130) 

14N/3E-24Q5S 09/08/1997 2.85 — 13.0 7.9 916 — 16.0 — 

14N/3E-24Q5S 07/28/2000 0.13 <20.0 2.0 29.0 902 — <10.0 38.0 

14N/3E-24Q5S 12/06/2011 0.03 <2.2 3.0 29.2 874 — 4.6 58.7 

14N/3E-26K1S 05/12/2011 0.03 28.4 33.3 2.9 999 — 11.8 18.4 

14N/3E-26K3S 12/08/2011 0.05 28.9 51.9 3.6 967 — 18.5 14.8 

14N/3E-26K4S 05/12/2011 0.02 5.1 14.5 21.0 995 — 4.7 33.9 

14N/3E-27E1S 11/29/1994 <0.01 — — — — — — — 14N/3E-27E1S 02/08/1995 <0.01 — — — — — — — 

14N/3E-27E1S 05/04/1995 0.01 — — — — — — — 

14N/3E-27E1S 05/08/1995 0.01 — — — 1,100 — <3.0 — 

14N/3E-27E1S 08/09/1995 <0.01 — — — — — — — 14N/3E-27E1S 11/07/1995 0.02 — — — — — — — 14N/3E-27E2S 11/29/1994 <0.01 — — — — — — — 14N/3E-27E2S 02/08/1995 <0.01 — — — — — — — 14N/3E-27E2S 05/04/1995 0.03 — — — — — — — 

14N/3E-27E2S 08/09/1995 <0.01 — — — — — — — 14N/3E-27E2S 11/07/1995 <0.01 — — — — — — — 14N/3E-27E3S 11/28/1994 <0.01 — — — — — — — 14N/3E-27E3S 02/08/1995 0.02 — — — — — — — 

14N/3E-27E3S 05/04/1995 <0.01 — — — — — — — 14N/3E-27E3S 08/08/1995 <0.01 — — — — — — — 14N/3E-27E3S 11/07/1995 0.01 — — — — — — — 14N/3E-28A1S 11/29/1994 0.01 — — — — — — — 14N/3E-28A1S 02/09/1995 <0.01 — — — — — — — 14N/3E-28A1S 05/05/1995 0.01 — — — 1,400 — <3.0 — 

14N/3E-28A1S 08/09/1995 0.02 — — — — — — — 

14N/3E-28A1S 11/08/1995 <0.01 — — — 1,500 — <3.0 — 

14N/3E-28H1S 11/29/1994 <0.01 — — — — — — — 14N/3E-28H1S 02/09/1995 <0.01 — — — — — — — 14N/3E-28H1S 05/05/1995 0.01 — — — — — — — 

14N/3E-28H1S 08/09/1995 <0.01 — — — — — — — 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Phosphorus, 

milligrams per liter 

as phosphorus

(P00666)

Aluminum, 

micrograms 

per liter

(P01106)

Arsenic, 

micrograms 

per liter

(P01000)

Barium, 

micrograms 

per liter

(P01005)

Boron, 

micrograms 

per liter

(P01020)

Chromium, 

micrograms 

per liter

(P01030)

Iron, 

micrograms 

per liter

(P01046)

Lithium, 

micrograms 

per liter

(P01130)

14N/3E-28H1S 11/08/1995 <0.01 — — — — — — — 14N/3E-28H2S 11/29/1994 <0.01 — — — — — — — 14N/3E-28H2S 02/09/1995 <0.01 — — — — — — — 14N/3E-28H2S 05/05/1995 <0.01 — — — — — — — 14N/3E-28H2S 08/09/1995 <0.01 — — — — — — — 14N/3E-28H2S 11/08/1995 <0.01 — — — — — — — 14N/3E-35C1S 03/29/2000 <0.05 <20.0 29.0 4.2 1,570 — 45.0 17.0 

14N/3E-35C2S 07/31/2000 E0.04 <20.0 30.0 5.6 1,990 — <10.0 20.0 

14N/4E-18N1S 05/21/1993 <0.01 <10.0 5.0 39.0 810 — 10.0 55.0 

14N/4E-18N1S 06/03/1993 — — — — — — — — 14N/4E-18N1S 09/23/1993 0.02 5.0 5.0 43.0 790 3.00 <3.0 60.0 

14N/4E-18N1S 09/14/1994 0.01 — 6.0 37.0 770 — <3.0 54.0 

14N/4E-18N1S 03/28/2000 <0.05 <20.0 5.0 40.7 761 — <10.0 54.0 

14N/4E-18N1S 12/09/2008 — <4.0 3.4 35.0 719 2.70 9.0 57.1 

14N/4E-18N1S 12/01/2010 <0.02 1.7 3.5 38.4 672 — 8.0 92.0 

State well 

number

Date

(mm/dd/yyyy)

Carbon-14 

counting error, 

percent modern carbon

(P49934)

Carbon-14, 

percent 

modern carbon

(P499331)

Tritium, 

in picocuries 

per liter

(P07000)

Tritium, 

in 

TU

Carbon-13/carbon-12 

ratio, 

per mil

(P82081)

Deuterium/proti

ratio, 

per mil

(P82082)

14N/3E-13K1S 06/03/1993 — — — — — — 

14N/3E-13M1S 05/21/1993 — — — — — –96.4 

14N/3E-13M1S 06/03/1993 — — — — — — 

14N/3E-13M1S 09/14/1994 — 15.3 — — –8.80 –96.8 

14N/3E-13M2S 07/14/1997 — — — — — –100.0 

14N/3E-13M2S 09/23/1997 0.08 1.3 <0.30 <0.09 –6.02 –98.7 

14N/3E-13M2S 07/30/2000 0.06 1.7 <0.30 <0.09 –5.98 –98.2 

14N/3E-13M3S 07/14/1997 — — — — — –96.4 

14N/3E-13M3S 09/23/1997 0.18 9.5 <0.30 <0.09 –7.41 –94.5 

14N/3E-13M3S 07/31/2000 0.11 6.4 <0.30 <0.09 –6.31 –92.5 

14N/3E-13M4S 09/24/1997 — — — — — –94.8 

14N/3E-13M4S 07/30/2000 0.12 6.0 <0.30 <0.09 –6.99 –93.6 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Carbon-14 counting error, percent modern carbon (P49934) Carbon-14, percent modern carbon (P499331) Tritium, in picocuries per liter (P07000) Tritium, in TU Carbon-13/carbon-12 ratio, per mil (P82081) Deuterium/proti

ratio, per mil (P82082) 

14N/3E-13M4S 12/02/2010 — — — — — –94.2 

14N/3E-14H1S 06/03/1993 — — — — — — 

14N3E-14H1S 07/29/1993 — — — — — –98.0 

14N/3E-14P1S 03/28/2000 0.15 6.6 <0.30 <0.09 –7.21 –94.5 

14N/3E-22N1S 05/19/1993 — — — — — –88.6 

14N/3E-22N1S 09/23/1993 — 112.7 — — –6.40 –88.5 

14N/3E-22N1S 09/21/1994 — — — — — –87.8 

14N/3E-22N1S 05/22/1996 — — — — — — 

14N/3E-22N1S 06/12/1996 — — — — — — 

14N/3E-22N1S 07/17/1997 0.19 12.1 <–0.16 <–0.05 –5.81 –89.3 

14N/3E-23B1S 03/02/2010 0.03 0.7 R0.10 R0.03 –6.22 –97.3 

14N/3E-23B2S 03/02/2010 0.04 1.7 0.70 0.22 –5.74 –96.5 

14N/3E-23B2S 12/05/2011 — — — — — –97.9 

14N/3E-23B3S 03/02/2010 0.09 5.4 R–0.20 R–0.06 –6.45 –93.7 

14N/3E-23B3S 12/05/2011 — — — — — –93.7 

14N/3E-23G1S 09/24/1993 — 18.6 <0.30 <0.09 –7.10 –89.6 

14N/3E-23G1S 09/21/1994 — 14.7 — — –7.40 –90.1 

14N/3E-23G1S 12/02/2010 — — — — — –92.8 

14N/3E-24H1S 07/29/1993 — — — — — –94.7 

14N/3E-24H1S 09/20/1994 — 114.3 — — –9.00 –95.6 

14N/3E-24Q1S 07/22/1997 — — — — — –99.7 

14N/3E-24Q1S 09/08/1997 0.12 5.6 <0.30 <0.09 –8.58 –101.0 

14N/3E-24Q1S 07/28/2000 0.09 4.2 <0.30 <0.09 –8.12 –100.0 

14N/3E-24Q2S 07/23/1997 — — — — — –100.0 

14N/3E-24Q2S 09/09/1997 0.11 5.0 <0.30 <0.09 –8.82 –99.4 

14N/3E-24Q2S 07/29/2000 0.10 4.2 <0.30 <0.09 –8.21 –97.8 

14N/3E-24Q3S 07/23/1997 — — — — — –99.7 

14N/3E-24Q3S 09/10/1997 0.12 3.6 <0.30 <0.09 –8.74 –102.0 

14N/3E-24Q3S 07/27/2000 0.09 2.8 <0.30 <0.09 –8.11 –101.0 

14N/3E-24Q4S 07/24/1997 — — — — — –94.8 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well 

number

Date

(mm/dd/yyyy)

Carbon-14 

counting error, 

percent modern carbon

(P49934)

Carbon-14, 

percent 

modern carbon

(P499331)

Tritium, 

in picocuries 

per liter

(P07000)

Tritium, 

in 

TU

Carbon-13/carbon-12 

ratio, 

per mil

(P82081)

Deuterium/proti

ratio, 

per mil

(P82082)

14N/3E-24Q4S 09/10/1997 0.18 8.4 <0.30 <0.09 –8.51 –94.0 

14N/3E-24Q4S 07/29/2000 0.14 8.1 <0.30 <0.09 –7.42 –94.3 

14N/3E-24Q5S 07/24/1997 — — — — — –95.0 

14N/3E-24Q5S 09/08/1997 0.14 7.1 <0.30 <0.09 –7.42 –94.4 

14N/3E-24Q5S 07/28/2000 0.11 6.1 <0.30 <0.09 –7.24 –92.9 

14N/3E-24Q5S 12/06/2011 — — — — — –95.4 

14N/3E-26K1S 05/12/2011 0.10 10.8 R0.30 R0.09 –8.12 –95.1 

14N/3E-26K3S 12/08/2011 0.14 6.9 R–0.30 R–0.09 –7.11 –94.7 14N/3E-26K4S 05/12/2011 0.10 11.3 R0.00 R0.00 –8.30 –95.0 

14N/3E-27E1S 11/29/1994 — — — — — — 

14N/3E-27E1S 02/08/1995 — — — — — — 

14N/3E-27E1S 05/04/1995 — — — — — — 

14N/3E-27E1S 05/08/1995 — — — — — –85.6 

14N/3E-27E1S 08/09/1995 — — — — — — 

14N/3E-27E1S 11/07/1995 — — — — — — 

14N/3E-27E2S 11/29/1994 — — — — — — 

14N/3E-27E2S 02/08/1995 — — — — — — 

14N/3E-27E2S 05/04/1995 — — — — — — 

14N/3E-27E2S 08/09/1995 — — — — — — 

14N/3E-27E2S 11/07/1995 — — — — — — 

14N/3E-27E3S 11/28/1994 — — — — — — 

14N/3E-27E3S 02/08/1995 — — — — — — 

14N/3E-27E3S 05/04/1995 — — — — — — 

14N/3E-27E3S 08/08/1995 — — — — — — 

14N/3E-27E3S 11/07/1995 — — — — — — 

14N/3E-28A1S 11/29/1994 — — — — — — 

14N/3E-28A1S 02/09/1995 — — — — — — 

14N/3E-28A1S 05/05/1995 — — — — — — 

14N/3E-28A1S 08/09/1995 — — — — — — 

14N/3E-28A1S 11/08/1995 — — — — — –87.5 

Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued[E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo<, less than; —, no data]
State well number Date (mm/dd/yyyy) Carbon-14 counting error, percent modern carbon (P49934) Carbon-14, percent modern carbon (P499331) Tritium, in picocuries per liter (P07000) Tritium, in TU Carbon-13/carbon-12 ratio, per mil (P82081) Deuterium/proti

ratio, per mil (P82082) 

14N/3E-28H1S 11/29/1994 — — — — — — 

14N/3E-28H1S 02/09/1995 — — — — — — 

14N/3E-28H1S 05/05/1995 — — — — — — 

14N/3E-28H1S 08/09/1995 — — — — — — 

14N/3E-28H1S 11/08/1995 — — — — — — 

14N/3E-28H2S 11/29/1994 — — — — — — 

14N/3E-28H2S 02/09/1995 — — — — — — 

14N/3E-28H2S 05/05/1995 — — — — — — 

14N/3E-28H2S 08/09/1995 — — — — — — 

14N/3E-28H2S 11/08/1995 — — — — — — 

14N/3E-35C1S 03/29/2000 0.20 11.5 <0.30 <0.09 –6.60 –92.3 

14N/3E-35C2S 07/31/2000 0.12 7.7 <0.30 <0.09 –5.43 –90.4 

14N/4E-18N1S 05/21/1993 — — — — — –96.1 

14N/4E-18N1S 06/03/1993 — — — — — — 

14N/4E-18N1S 09/23/1993 — 19.1 <0.30 <0.09 –9.20 –96.7 

14N/4E-18N1S 09/14/1994 — 110.4 — — –8.50 –96.5 

14N/4E-18N1S 03/28/2000 — — — — — –96.9 

14N/4E-18N1S 12/09/2008 0.09 8.2 R0.00 R0.00 –8.31 –97.5 

14N/4E-18N1S 12/01/2010 — — — — — –97.7 

1Parameter code P82172, used prior to 1995, is described in the National Water Information System (NWIS) as carbon-14 age, apparent, dissolved, by liquid scintillation (ana

Isotope Lab). Table 3–1. Water-quality data for selected wells in Bicycle Basin at Fort Irwin National Training Center, California, 1993–2011.—Continued [E, estimated; ft, feet; hhmm, hour minute; ID, identification; mm/dd/yyyy, month/day/year; R, reported by the U.S. Geological Survey (USGS) Stable Isotope and Tritium Labo

<, less than; —, no data]
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For more information concerning the research in this report, contact the

 Director, California Water Science Center

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6000 J Street, Placer Hall

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https://ca.water.usgs.gov ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20185067
Densmore and others—Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin, Fort Irwin 

National Training Center, California—Scientific Investigations Report 2018–5067

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20185067