Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model Rev 01, ICN 00 Errata

ANL-NBS-HS-000034

December 2001

1. PURPOSE 
This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed 
to provide the saturated-zone, site-scale flow and transport model (CRWMS M&O 2000) with the 
configuration of the potentiometric surface, target water-level data, and hydraulic gradients for 
model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, 
Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 
2001). This analysis is designed to use updated water-level data as the basis for estimating waterlevel 
altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. 
The objectives of this revision are to develop computer files containing (1) water-level data within 
the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: 
GS010908312332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using 
an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north 
of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early 
Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being 
utilized by the SZ site-scale flow and transport model, the water-level data and potentiometricsurface 
map contained within this report will be available to other government agencies and water 
users for ground-water management purposes. The potentiometric surface defines an upper 
boundary of the site-scale flow model, as well as provides information useful to estimation of the 
magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis 
documented in this revision is important to SZ flow and transport calculations in support of total 
system performance assessment. 
The source data associated with this analysis include water-level data from boreholes within, and 
from one borehole (UE-25 J-11) adjacent to, the SZ site-scale flow and transport model area. The 
SZ site-scale flow and transport model area (Figure 1-1) is between a Universal Transverse 
Mercator (UTM) Easting of 533,340 meters and 563,340 meters and a UTM Northing of 4,046,782 
meters and 4,091,782 meters (Zone 11, North American Datum 1927). The following types of 
information were gathered: borehole site name/identification (ID), location, land-surface altitude, 
water-level altitude, data source, reliability of data, minimum and maximum water levels (range), 
and open interval monitored with the associated water-level altitude and type. 
Development of the original, Rev 00, AMR was performed pursuant to AMR Development Plan 
TDP-NBS-HS-000099 (USGS 2000) in accordance with AP-2.13Q, Technical Product 
Development Planning. This revision, Rev 01, to the previous analysis was prepared as part of 
activities being conducted under Technical Work Plan, TWP-NBS-MD-00001, Rev 01, Technical 
Work Plan for Saturated Zone Flow and Transport Modeling and Testing (BSC 2001). The TWP 
was prepared in accordance with AP-2.21Q, Quality Determinations and Planning for Scientific 
Engineering, and Regulatory Compliance Activities. No deviations from the TWP were necessary 
to complete this revision of the AMR.

Title: Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
 7 
The scope of this revision includes: 
 Compilation of available water-level data within the model area; 
 Removal of duplicate measurements and sites; 
 Tabulation of measurement precision, where known; 
 Assessment of the general reliability of the data; 
 Tabulation of the range in water levels for use in uncertainty analyses; 
 Documentation of the applicable use of water levels (potentiometric-surface development 
and/or SZ site-scale flow and transport model calibration); 
 Generation of the potentiometric-surface map representative of the early 1990s (the time 
period of the saturated-zone, regional-scale flow model (DAgnese et al. 1997) that is used 
to provide boundary conditions to the SZ site-scale flow and transport model, CRWMS 
M&O 2000); and 
 Generation of a table of known vertical head differences within the SZ site-scale flow and 
transport model area. These head differences provide additional calibration targets for the 
model. 
In this analysis, the water-level data are used to generate a single representative potentiometric 
surface (Figure 6-1) for the SZ site-scale flow and transport model domain. This revision of the 
potentiometric surface represents an alternate concept from that presented in Rev 00 ICN 01 of this 
report (USGS 2001) of the northern part of Yucca Mountain, which has been termed the large 
hydraulic gradient area (Ervin et al., 1994, p. 7). This concept assumes that water levels in 
boreholes USW G-2 and UE-25 WT #6 represent perched conditions, and are not representative of 
the regional potentiometric surface.

 
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Figure 1-1 Location Map of the Study Area and Associated Geographic Features

 
 9 
2. QUALITY ASSURANCE 
The activities documented in this revision were evaluated in accordance with AP-2.21Q, Quality 
Determinations and Planning for Scientific, Engineering, and Regulatory Compliance Activities, 
and were determined to be subject to the requirements of the U.S. DOE Office of Civilian 
Radioactive Waste Management (OCRWM) Quality Assurance Requirements and Description 
(QARD) (DOE 2000), pursuant to the Activity Evaluation prepared to support Technical Work 
Plan TWP-NBS-MD-000001 (BSC 2001). This revision has been prepared in accordance with 
procedure AP-3.10Q, Analyses and Models. 
During development of this revision, all data were kept in the Principal Investigators (PI) 
designated area on the H drive of the USGS server in Denver, Colorado. This directory is fully 
backed up weekly, with incremental backups 3 times a week, and is accessible only to the PI and the 
USGS computer site administrator. Additional backups were performed by the PI, on either floppy 
disk or CD-ROM. These data management activities comply with the guidance specified in 
AP-SV.1Q, Control of the Electronic Management of Data, and are documented in Scientific 
Notebook, SN-USGS-SCI-126-V1, Revision of Water-Level AMR (ANL-NBS-HS-000034, 
Rev 00/ICN 01) (Tucci 2001).

 
 10 
3. COMPUTER SOFTWARE AND MODEL USE 
The water-level data were compiled and the potentiometric surface was constructed using 
Geographic Information System (GIS), spreadsheet, and digitizing software. No controlled software 
codes were used to synthesize the water-level data for the SZ site-scale flow and transport model. 
ARCINFO Version 7.2.1 was obtained from Software Configuration Management, was appropriate 
for the application, and was used only within its range of validation in accordance with the 
requirements of AP-SI.1Q, Software Management. PETROSYS, which was used in ANL-NBS-HS- 
000034, Rev 00 ICN 01 (USGS 2001) for gridding and contouring, was not used in this revision. 
The potentiometric surface shown on Figure 6-1 was hand-contoured, precluding the need for 
contouring software. 
Table 3-1 Software Used to Support Analysis Activity 
Software Name Version 
Software 
Tracking 
Number 
Computer Platform, 
Operating System, 
Compiler Description 
ARCINFO 7.2.1 STN: 
10033-7.2.1-01 
Windows NT Workstation 
ver. 4.0. CPU ID#: 
15409290306. Location: 
San Diego Projects Office, 
USGS/WRD, San Diego, CA 
Plotting, coordinate 
transformation, and 
visualization of analysis 
results. 
A brief description of how the software was used follows. 
ARCINFO Version 7.2.1 (STN: 10033-7.2.1-01), published by Environmental Systems Research 
Institute, Inc., was used for plotting, coordinate transformation, and visualization of analysis results. 
Microsoft Excel 97 SR-2 (exempt per AP-SI.1Q ) was used to compile water-level data, and to 
compute average water levels using the AVG function of the software. Conversion of feet to 
meters was often done within Excel, by using the equation (meters = feet * 0.3048). These simple 
conversions were spot checked with hand calculations. The original Excel spreadsheets (inputs) 
were obtained from the Technical Data Management System (TDMS) (see Table 4-1). The 
calculated average water levels (outputs) are listed in Attachment I, Table I-1, and are contained in 
DTN: GS010908312332.002. 
AutoCAD Map 2000, release 4 (exempt per AP-SI.1Q ) was used to digitize the hand-drawn 
potentiometric contours. The output digitized contours were used as input to ARCINFO for 
plotting. 
No model was used to support this analysis.

 
 11 
4. INPUTS 
4.1 DATA AND PARAMETERS 
The data used to construct the potentiometric surface and to define water levels in selected 
boreholes for flow-model calibration were developed from available measurements of water levels 
in boreholes throughout and adjacent to the SZ site-scale flow and transport model domain. These 
data, together with assessments of their accuracy and reliability, are presented in Tables I-1 through 
I-8 of Attachment I. In general these water-level measurements represent the configuration of the 
potentiometric surface in the upper part of the saturated zone, and no additional control is available 
from springs or other surface-water occurrences. Therefore, these data are considered to be 
appropriate for their intended use in defining the upper boundary and determining lateral hydraulic 
gradients for the SZ site-scale flow and transport model. Some water levels were obtained from 
deeper parts of the ground-water flow system, and these data provide information on vertical 
hydraulic gradients that are important for calibration of the SZ site-scale flow and transport model. 
Additional justification for the appropriateness of the data is documented in: 
 Section 1 (Purpose), which describes the scope of the data used; 
 Section 5.1 (Assumptions  Water-Level Data), which addresses assumptions concerning 
the use of the data; 
 Section 6.1 (Analysis  Water-Level Data), which discusses the analysis of the water-level 
data; and 
 Section 7.1 (Conclusion  Water-Level Data), which discusses potential errors and 
uncertainty. 
All water-level data available for the SZ site-scale flow and transport model area were evaluated; 
however, some data were considered invalid. Data that were identified as invalid in ANL-NBS-HS- 
000034, Rev 00 ICN 01 (USGS (2001) are not used in this revised analysis. New data that were 
considered for use in this analysis were evaluated for validity and documented in scientific notebook 
SN-USGS-SCI-126-V1 (Tucci 2001), and the reasons for considering these new data to be invalid 
are described as follows. Based on observations of water-level data at Yucca Mountain, water 
levels generally fluctuate less than 1 m, and more often, less than 0.5 m (Graves et al. 1997). 
Exceptions occur if a nearby well is pumped or if water levels are affected by seismic events. Most 
of the data that were considered invalid in this analysis consisted of data obtained prior to 
development of the well, or were a result of known or suspected equipment failures. For example, 
water-level data are obtained from transducers, set in discrete zones isolated by packers, in wells 
NC-EWDP-1S, NC-EWDP-3S, and NC-EWDP-9SX. Transducers are known to be subject to drift, 
failure, or electronic problems. Packers occasionally will fail to seat properly, causing an 
incomplete isolation of a zone, or can leak and fail. Transducer data were considered to be invalid if 
they indicated either slow drifting of water levels or sharp spikes. Such phenomena could be valid, 
but they would have to occur in more than one zone in a well and in more than one well to be 
considered valid. Such corresponding changes in other zones or wells rarely occurred, so that the 
anomalous data were considered invalid.

 
 12 
Fault locations and traces (Figure 6-1; DTN: GS991208314221.001) were used as input data to 
construct the potentiometric-surface map. Ground-water flow may be affected by faults, which may 
act as barriers and/or conduits for flow. The locations of major faults in the SZ site-scale flow and 
transport model area were used to help guide the placement of potentiometric contours according to 
their assumed effect on ground-water flow (see Section 5.2). 
Specific input data sets, and associated Data Tracking Numbers (DTNs), are listed in Table 4-1. 
The qualification status of these input sources can be found in the Document Input Reference 
System (DIRS). 
Table 4-1 Input Data Sources 
Data Description Data Tracking Number 
Digital Elevation Models Death Valley East Scale 1:250,000. GS000400002332.001 
Water-Level Measurements at UE-25 C #2 and C #3, 1989. GS000408312312.001 
Water-Level Altitude Data from the Periodic Network, January 1999 through 
March 1999. 
GS000608312312.003 
Revised Water-Level Altitude Data from the Periodic Network, First Quarter 
1995. 
GS000608312312.004 
Water-Level Altitude Data, 1993. GS000708312312.005 
Ground-Water Altitudes from Manual Depth-to-Water Measurements at 
Various Boreholes November 1998 through December 1999. 
GS000808312312.007 
Geohydrology of Rocks Penetrated by Test Well UE-25p#1 (UE-25 p#1), 
Yucca Mountain Area, Nye County, Nevada. 
GS920408312314.009 
Geohydrologic Data and Test Results from Well J-13, Nevada Test Site, Nye 
County, Nevada. 
GS930408312132.007 
Water Levels in the Yucca Mountain Area, Nevada, 1990-91. GS930408312312.015 
Water Levels in Periodically Measured Wells in the Yucca Mountain Area, 
Nevada, 1981-87. 
GS931008312312.025 
Water-Level Altitude Data from the Periodic Network, Fourth Quarter, 1994. GS950108312312.001 
Potentiometric-Surface Map, 1993, Yucca Mountain and Vicinity, Nevada. GS950508312312.005 
28 Water-Level Measurements from the Periodic Network, Third Quarter, 
1995 (7/1/95 - 9/30/95). 
GS960208312312.003 
Analysis of Water-Level Data in the Yucca Mountain Area, Nevada, 1985- 
1995. 
GS960908312312.010 
Water Level Altitude Data Collected at GEXA Well 4 and USW G-4. GS970600012847.001 
Water Levels in the Yucca Mountain Area, Nevada, 1996. GS980308312312.004 
Water-Level Altitude Data, April - June 1999. GS990908312312.005 
Water Level Data for Yucca Mountain Region and Amargosa Desert. GS991100002330.001 
Geologic Map of the Yucca Mountain Region. GS991208314221.001 
Water-Table-Altitude Data for Well USW G-4, Yucca Mountain Area, Nye 
County, Nevada. 
MO0008WTRALTG4.000 
Locations and Elevations for Selected Wells in the Yucca Mountain Region 
and Amargosa Desert from the USGS NWIS Database. 
MO0011ELLOCAMD.000 
Coverage: BORES3Q. MO0103COV01031.000 
Coverage: NCEWDPS. Submittal date: 07/18/2001. MO0107COV01057.000 
Water Level Data From Westbay Instrumented Borehole NC-EWDP1S. MO0111DQRWLNYE.002 
Water Level Data From Westbay Instrumented Borehole NC-EWDP-3S. MO0111DQRWLNYE.003 
Water Level Data From Westbay Instrumented Borehole NC-EWDP-9SX. MO0111DQRWLNYE.004 
Well Completion Diagram For Borehole NC-EWDP-4PA. MO0112DQRWLNYE.005

 
 13 
Data Description Data Tracking Number 
Well Completion Diagram For Borehole NC-EWDP-4PB. MO0112DQRWLNYE.006 
Well Completion Diagram For Borehole NC-EWDP-7S. MO0112DQRWLNYE.007 
Well Completion Diagram For Borehole NC-EWDP-5SB. MO0112DQRWLNYE.008 
Well Completion Diagram For Borehole NC-EWDP-15P. MO0112DQRWLNYE.009 
Well Completion Diagram For Borehole NC-EWDP-12PA. MO0112DQRWLNYE.010 
Well Completion Diagram For Borehole NC-EWDP-9SX. MO0112DQRWLNYE.011 
Well Completion Diagram For Borehole NC-EWDP-12PB. MO0112DQRWLNYE.012 
Well Completion Diagram For Borehole NC-EWDP-12PC. MO0112DQRWLNYE.013 
Well Completion Diagram For Borehole NC-EWDP-19P. MO0112DQRWLNYE.014 
Well Completion Diagram For Borehole NC-EWDP-3S. MO0112DQRWLNYE.015 
Well Completion Diagram For Borehole NC-EWDP-3D. MO0112DQRWLNYE.016 
Well Completion Diagram For Borehole NC-EWDP-1DX. MO0112DQRWLNYE.017 
Well Completion Diagram For Borehole NC-EWDP-19D. MO0112DQRWLNYE.018 
Multi-Level Monitoring Port Depths In Nye County Boreholes NC-EWDP-1S, 
-3S AND -9SX. 
MO0112DQRWLNYE.019 
Water Level Depth Data For Nye County Boreholes NC-EWDP-2D AND - 
2DB. 
MO0112DQRWLNYE.020 
Multilevel Piezometer Casing Log For Borehole NC-EWDP-9SX. MO0112DQRWLNYE.021 
Multilevel Piezometer Casing Log For Borehole NC-EWDP-3S. MO0112DQRWLNYE.022 
Multilevel Piezometer Casing Log For Borehole NC-EWDP-1S. MO0112DQRWLNYE.023 
EWDP Phase I Manual Water Level Measurements. MO0112DQRWLNYE.024 
EWDP Phase II Manual Water Level Measurements. MO0112DQRWLNYE.025 
USW SD-7 Shift Drilling Summaries (1602.0'-2020.3'), Lithologic Logs 
(1600.0'-1925.0'), and Structure Logs (1632.0'-2020.3'). 
TM0000000SD7RS.003 
USW SD-9 Shift Drilling Summaries, Structural Logs, and Lithological Logs. TM0000000SD9RS.001 
USW SD-12 Shift Drilling Summaries, Lithologic Logs, and Structure Logs 
from 1825.0'-2166.3'. 
TM000000SD12RS.011 
The locations of boreholes, the water-level altitudes in these boreholes, and the potentiometric 
contours are shown in Figure 6-1. The borehole data are provided in Attachment I. 
4.2 CRITERIA 
This revision addresses Subpart B, 10 CFR 63 (66 FR 55732). Subparts of the regulation that apply 
to this analysis activity are those pertaining to the characterization of the Yucca Mountain site 
(Subpart B, Section 63.15), the compilation of information regarding hydrology of the site in 
support of the License Application (Subpart B, Section 63.21(c)(1)(ii)), and the definition of 
hydrologic parameters and conceptual models used in performance assessment (Subpart E, Section 
63.114(a)).

 
 14 
4.3 CODES AND STANDARDS 
No codes or standards have been identified as applying to this analysis.

 
 15 
5. ASSUMPTIONS 
5.1 WATER-LEVEL DATA 
In the analysis presented in this report, several assumptions are made as described in the following 
subsections. The nature of these assumptions entails established hydrologic practices for the 
determination of water-level altitudes to be used in the construction of a potentiometric-surface map 
and requires no further confirmation. 
1. Assumption: Averaging water levels from the 1980s to 1990s and 2000 provide water-level 
altitudes representative of conditions that existed in early 1990s. The SZ site-scale flow and 
transport model (CRWMS M&O 2000) uses ground-water fluxes from the Death Valley 
regional ground-water flow model (hereafter referred to as the regional model) (DAgnese et al. 
1997) as calibration targets. The simulated fluxes in the regional model represent average, 
assumed steady-state conditions from the early 1990s, not conditions for a specific year. 
Therefore, the water levels used to construct the potentiometric surface for the site-scale model 
must, to the extent allowed by data availability, represent conditions consistent with the regional 
model that used water-level data (altitudes) representing the early 1990s. Water levels in 
boreholes located at Yucca Mountain generally have not fluctuated by more than one meter 
during the time period from 1985 until 1995 (Graves et al. 1997). Some of the boreholes used in 
this analysis had no or very few water-level measurements taken during the 1980s and 1990s 
(Attachment I, Tables I-2 and I-4). For boreholes in this category, all available water-level 
altitudes, with the exception of anomalous ones noted in Attachment I, were used to calculate 
the mean water-level altitude (Attachment I, Table I-1). This is particularly true for boreholes 
located in the Amargosa Valley and Amargosa Desert (Figure 6-1). Boreholes listed in 
Attachment I, Table I-2 as unreliable (U) or assumed perched (P) are shown on Figure 6-1, 
but were not used to construct the potentiometric surface. This assumption is used in Section 
6.1 and Attachment I, Table I-1. 
2. Assumption: Mean water-level altitudes, even when influenced by ground-water withdrawal, 
represent water-level altitudes consistent with ground-water fluxes used in the SZ site-scale flow 
and transport model. Some boreholes in the model area are pumped for commercial and 
domestic water supplies. Water-level altitudes in these and adjacent boreholes could be 
influenced by the effects of pumping. This condition is especially true in the southern part of 
the SZ site-scale flow and transport model area. The mean water-level altitude, calculated by 
averaging available data, provides a datum point that is representative of the potentiometric 
surface for the time period being simulated. The rationale is that average-annual pumping 
values were used in the regional model (DAgnese et al. 1997) and average water levels will, 
therefore, be consistent with the simulated conditions in the regional model. This assumption is 
used in Section 6.1 of this revision. 
3. Assumption: Where measurement location (vertical) is unknown, the midpoint of the open 
interval or applicable packed-off interval is representative of the measurement location for SZ 
site-scale flow and transport modeling purposes. Most of the water levels used in this analysis 
are composite data, for a long open or screened interval. In open boreholes, the midpoint can be 
calculated as the mean of the altitude of the bottom of the borehole and the altitude of the

 
 16 
maximum water-level altitude. In packed-off intervals (screened intervals), the midpoint is 
calculated as the mean of the altitude of the bottom of the packed-off interval and the altitude of 
the top of the packed-off interval. Because this method is used for all boreholes that contributed 
water-level altitude data for this analysis, it provides a means for standardizing SZ measurement 
locations (Attachment I, Table I-5). This assumption is used throughout the revision. 
4. Assumption: Water levels in boreholes USW G-2, UE-25 WT #6, and NC-EWDP-7S are 
perched. Water levels in boreholes USW G-2 and UE-25 WT #6, in the northern part of Yucca 
Mountain are assumed to represent perched conditions for the alternate concept of the largehydraulic 
gradient area presented in this analysis. Czarnecki et al. (1997, p. 27) presents several 
lines of evidence to support this assumption. Water levels in borehole NC-EWDP-7S, in 
southern Crater Flat, are also assumed to represent perched conditions. The water levels for 
NC-EWDP-7S are anomalously high (Attachment I, Table I-1; Figure 6-1), and no other 
hydrogeologic explanation other than perched conditions is plausible for this location. This 
assumption is used in Section 6.2. 
5. Assumption: Water levels in USW WT-24, at approximately 840 m above sea level, represent 
the regional potentiometric level. During drilling, a water-bearing fracture was encountered at 
about 760 m below land surface, and water rose in the borehole to an altitude of about 840 m 
above sea level. Drilling continued for another 104 m below the water-bearing fracture without 
any significant change in the water level (Graves 2001). Because the potentiometric level 
persisted as the borehole was considerably deepened, and because the water level remained 
relatively stable after completion of the well, the 840 m level is assumed to represent the 
regional potentiometric level and not a perched level. This assumption is used in Section 6.2. 
5.2 POTENTIOMETRIC-SURFACE MAP 
1. Assumption: It is assumed that the water level from the uppermost open interval from each 
borehole at each site, except those boreholes listed in Assumption 4 in Section 5.1, represents 
the potentiometric surface of the uppermost part of the saturated zone (i.e., the water table). 
Most boreholes have only one water-level measurement interval, however, several boreholes 
have two or more isolated measurement intervals (Attachment I, Table I-5). In most boreholes, 
the uppermost interval is where the water was first encountered in the borehole (excluding 
perched-water zones, where identified). The significance of this assumption is that the resulting 
configuration of the potentiometric surface helps to determine the magnitude and direction of 
lateral ground-water flow in the upper SZ, which is important in the evaluation of potential 
radionuclide transport down gradient from the potential repository. This assumption is used in 
Section 6.2. 
2. Assumption: Faults may act as barriers and/or conduits for ground-water flow. The concept 
used in the placement of potentiometric contours (Section 6.2, Figure 6-1) is that ground-water 
flow across a fault or fault zone is impeded by the fault, and ground-water flow parallel to a fault 
or fault zone is not impeded. The concept that faults may act, alternatively, as barriers to or 
conduits for groundwater flow is pointed out by Freeze and Cherry (1979, p. 474). Within the 
saturated zone underlying Yucca Mountain, this assumption is further justified by the 
observations of Luckey et al. (1996, pp. 25 and 56) (1) that the Solitario Canyon fault along the

 
 17 
west side of Yucca Mountain is an apparent barrier to flow from west to east across the fault and 
(2) that, where fault zones are intersected by boreholes, these zones act as conduits for flow and 
produce much of the water entering the boreholes (Luckey et al. 1996, p. 37). 
5.3 BOREHOLE LOCATIONS 
1. Assumption: Borehole locations used in this analysis from DTN: MO0011ELLOCAMD.000 
are sufficiently accurate for the intended purpose. Borehole coordinates and altitudes from YMP 
boreholes in DTN: MO0011ELLOCAMD.000 and in DTN: MO0103COV01031.000, which 
only contains YMP boreholes, were compared. Small differences in the northing and easting 
coordinates contained in the two records exist in most borehole locations. The altitudes of the 
boreholes in the two data sets were identical. Borehole altitude is the most critical component of 
the borehole location used for calculating the water-level altitude. Where there are differences 
in northing and easting coordinates, the differences are not large enough to adversely effect the 
location of the potentiometric-contour lines. This assumption is used throughout this revision.

 
 18 
6. ANALYSIS/MODEL 
The water-level data and the resulting potentiometric-surface map provide important technical input 
for the development of the SZ site-scale flow and transport model. Saturated Zone Flow, though not 
a Principal Factor, may be considered in evaluating postclosure performance of the repository 
system and therefore may be taken into account in the postclosure safety case as identified within 
the Repository Safety Strategy (CRWMS M&O 2001). Consequently, inputs to this revision are 
determined to be related to Other Factors pursuant to the screening criteria outlined in AP-3.15Q, 
Managing Technical Product Inputs. 
6.1 WATER-LEVEL DATA 
The water-level data for the SZ site-scale flow and transport model were compiled from project data 
sources and U.S. Geological Survey (USGS) National Water Information System (NWIS) waterlevel 
data. This data set was updated using new (collected through December 2000) information 
from the Nye County Early Warning Drilling Program boreholes, data from borehole USW WT-24, 
and from geologic mapping within the model area (DTN: GS991208314221.001). Water-level 
information and analyses were compiled from the data sources listed in Table 4-1 of this revision. 
The results were assembled in tabular format for use as input to the SZ site-scale flow and transport 
model (see Attachment I). 
Water-level information used in this analysis was derived from a variety of sources. The large areal 
extent of the SZ site-scale flow and transport model, and the long history of water-level data 
collection in this area, has resulted in similar (or in some cases duplicate) water-level information 
being contained in multiple data sources. If more than one site ID was found in NWIS for the same 
borehole, the site ID with the most measurements was used for calculating the average water-level 
altitude for the time period of interest. If location, land-surface altitude, or depth-to-water for a 
borehole were not available, the site was not used. NWIS data are stored as depth-to-water 
measurements, not as water-level altitude, and in English units as opposed to metric units. 
Conversion from depth-to-water to water-level altitude was accomplished by subtracting the depthto-
water measurement from the land-surface altitude of the measurement location (the borehole and 
surface altitude). The resulting water-level altitude was converted from feet to meters by 
multiplying by 0.3048. 
Borehole information was examined to see if water levels potentially represented perched-water 
conditions. Professional judgment was used to determine whether water-level altitudes represented 
perched-water conditions, based on the following criteria: proximity to cold-water springs, 
proximity to recharge areas, steep or anomalous potentiometric surface slope, anomalous waterlevel 
altitudes, statistical water-level variability, water chemistry, pumping history, and hydrographs 
(OBrien 1998). Potential perched-water levels identified during this analysis were flagged and 
identified as suspected perched or assumed perched (Attachment I, Tables I-2 and I-8). To 
prove perched-water occurrence unequivocally requires demonstrating partial saturation beneath a 
suspected perched-water body. The boreholes in question were either drilled using a water-based 
circulating fluid or were only completed a few tens of meters into the first zone of saturation. 
Unfortunately, partial saturation could not be proved or disproved unequivocally with the available 
data for the boreholes in question, USW G-2, USW G-1, UE-29 a #2, UE-25 a #3, USW UZ-N91,

 
 19 
UE-25 WT #18, UE-25 WT #6 (OBrien 1998), and NC-EWDP-7S (DTN: 
MO0112DQRWLNYE.007). In this analysis, however, water levels for wells USW G-1, UE-29 a 
#2, UE-25 a #3, USW UZ-N91, and UE-25 WT #18 are believed to not represent perched water 
areas. Water levels for these wells are consistent with the alternative concept of the large hydraulic 
gradient presented here and with the water level in USW WT-24. 
6.1.1 Vertical Head Differences 
Within the SZ site-scale flow and transport model area, 17 boreholes monitor, or have historically 
monitored, water levels in more than one vertical interval (Table 6-1). Water-level data from these 
boreholes allow for the calculation of the difference in potentiometric heads at each monitored 
interval. Both upward (head increases with depth) and downward (head decreases with depth) 
vertical gradients have been observed. Fewer downward gradients (5) are observed than upward 
gradients (12). Upward vertical head differences range from 0.1 m to almost 55 m, and downward 
vertical head differences range from 0.5 to 38 m. The monitored intervals were selected to either 
monitor water levels between different geologic units or between different permeable intervals 
within the same geologic unit. 
Only two sites, UE-25 p #1, and NC-EWDP-2D/2DB, (Table 6-1), provide information on vertical 
gradients between volcanic rocks and the underlying Paleozoic carbonate rocks. At UE-25 p #1, 
water levels currently are monitored only in the carbonate aquifer; however, water-level data were 
obtained from within the volcanic rocks as the borehole was drilled and tested (DTN: 
GS920408312314.009). At this site water levels in the Paleozoic carbonate rocks are about 20 m 
higher than those in the overlying volcanic rocks. Borehole NC-EWDP-2DB penetrated Paleozoic 
carbonate rocks toward the bottom of the borehole (Spengler 2001). Water levels measured within 
that deep part of the borehole are about 8 m higher than levels measured in volcanic rocks 
penetrated by borehole NC-EWDP-2D. 
Water levels monitored within the lower part of the volcanic-rock sequence at Yucca Mountain also 
are significantly higher than levels monitored in the upper part of the volcanics. Boreholes 
USW H-1 (tube 1) and USW H-3 (lower interval) both monitor water levels in the lower part of the 
volcanic-rock sequence, and upward gradients are observed at these boreholes with head differences 
of 54.7 m, and 28.9 m, respectively (Table 6-1). The gradient at USW H-3 is not completely 
known, because the water levels in the lower interval had been continuously rising before the packer 
that separates the upper and lower intervals failed in 1996. 
An upward gradient is also observed between the alluvial deposits monitored in borehole NCEWDP-
19P and underlying volcanic rocks monitored in borehole NC-EWDP-19D (Table 6-1). The 
vertical head difference at this site is 5.3 m; however, levels reported for NC-EWDP-19D represent 
a composite water level for both alluvium and volcanics, so that the true head difference between 
those units is not completely known. 
Downward gradients are also observed within the SZ site-scale flow and transport model area 
(Table 6-1). The largest downward gradient is observed between the deep and shallow monitored 
intervals at borehole NC-EWDP-1DX (head difference of 38 m). The depth to water at this site is

 
 20 
very shallow (17 m), and within Tertiary spring deposits. Other downward gradients are much 
smaller in magnitude. 
Five wells or well sites with more than 2 monitoring intervals (Table 6-1; well USW H-1, well 
USW H-6, well UE-25 J -13, site NC-EWDP-3D/NC-EWDP-3S, and well NC-EWDP-9SX) have 
head differences between the upper-most and lower-most monitored intervals and the intermediate 
intervals in which the gradients are both upwards and downwards. For example at well USW H-1, 
the head difference between the upper-most (tube 4) and next lower interval (tube 3) is 0.2 meters, 
indicating a small downward gradient; however, the head difference between tube 3 and the next 
lower interval (tube 2) is 5.3 meters, indicating an upward gradient. The significance of the mixed 
gradients at these sites on overall ground-water flow paths is not known at this time, because of the 
limited number of data points. 

 
 21 
Table 6-1 Vertical Head Differences (Output DTN: GS010908312332.003) 
WELL 
OPEN 
INTERVAL 
(m below 
land surface) 
POTENTIOMETRIC 
LEVEL 
(m above sea level) 
HEAD DIFFERENCE 
deepest - shallowest 
intervals (m) 
Source Data REMARKS 
USW H-1 tube 4 573-673 730.94 54.7 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-1 tube 3 716-765 730.75 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-1 tube 2 1097-1123 736.06 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-1 tube 1 1783-1814 785.58 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-3 upper 762-1114 731.19 28.9 GS980308312312.004 1996 mean level, Graves (1998, p. 59) 
USW H-3 lower 1114-1219 760.07 GS980308312312.004 1996 mean level, Graves (1998, p. 59) 
USW H-4 upper 525-1188 730.49 0.1 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-4 lower 1188-1219 730.56 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-5 upper 708-1091 775.43 0.2 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-5 lower 1091-1219 775.65 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-6 upper 533-752 775.99 2.2 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-6 lower 752-1220 775.91 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
USW H-6 1193-1220 778.18 GS931008312312.025 1/84-5/84 mean level, Luckey et al. 1996, 
table 3 
UE-25 b #1 upper 488-1199 730.71 -1.0 GS930408312312.015 1991 mean level, Luckey et al. 1996, table 3 
UE-25 b #1 lower 1199-1220 729.69 GS930408312312.015 1990-91 mean level 
UE-25 p #1 (volcanic) 384-500 729.90 21.4 GS920408312314.009 Luckey et al. 1996, table 3 
UE-25 p #1 (carbonate) 1297-1805 751.26 GS920408312314.009 Luckey et al. 1996, table 3 
UE-25 c #3 692-753 730.22 0.4 GS930408312312.015 1990 mean level, Luckey et al. 1996, table 3 
UE-25 c #3 753-914 730.64 GS930408312312.015 1990 mean level, Luckey et al. 1996, table 3 
USW G-4 615-747 730.3 -0.5 MO0008WTRALTG4.000 Luckey et al. 1996, table 3 
USW G-4 747-915 729.8 MO0008WTRALTG4.000 Luckey et al. 1996, table 3 
UE-25 J -13 upper 282-451 728.8 -0.8 GS930408312132.007 Luckey et al. 1996, table 3 
UE-25 J -13 471-502 728.9 GS930408312132.007 Luckey et al. 1996, table 3 
UE-25 J -13 585-646 728.9 GS930408312132.007 Luckey et al. 1996, table 3 
UE-25 J -13 820-1063 728.0 GS930408312132.007 Luckey et al. 1996, table 3

 
 22 
WELL 
OPEN 
INTERVAL 
(m below 
land surface) 
POTENTIOMETRIC 
LEVEL 
(m above sea level) 
HEAD DIFFERENCE 
deepest - shallowest 
intervals (m) 
Source Data REMARKS 
NC-EWDP-1DX 
(shallow) 
WT-419 786.8 -38.0 MO0112DQRWLNYE.017, 
MO0112DQRWLNYE.024 
5/99-2/00 
NC-EWDP-1DX (deep) 658-683 748.8 MO0112DQRWLNYE.024 
MO0112DQRWLNYE.017 
8/99-2/00 
NC-EWDP-2D 
(volcanic) WT-493 
706.1 7.6 MO0112DQRWLNYE.020, 
MO0112DQRWLNYE.024 
1/99 
NC-EWDP-2DB 
(carbonate) 
820-937 713.7 MO0112DQRWLNYE.020, 
MO0112DQRWLNYE.025 
11/15/00-11/22/00 
NC-EWDP-3S probe 2 103-129 719.8 -1.5 MO0112DQRWLNYE.015, 
MO0112DQRWLNYE.019, 
MO0111DQRWLNYE.003, 
MO0112DQRWLNYE.022 
5/06/99-12/06/00 
NC-EWDP-3S probe 3 145-168 719.4 MO0112DQRWLNYE.015, 
MO0112DQRWLNYE.019, 
MO0111DQRWLNYE.003, 
MO0112DQRWLNYE.022 
5/06/99-12/06/00 
NC-EWDP-3D WT-762 718.3 MO0112DQRWLNYE.024, 
MO0112DQRWLNYE.016 
3/99-8/99 
NC-EWDP-4PA 124-148 717.9 5.7 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.005 
1/13/00-10/26/00 
NC-EWDP-4PB 225-256 723.6 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.006 
1/21/00-10/26/00 
NC-EWDP-9SX probe 1 27-37 766.7 0.1 MO0112DQRWLNYE.011, 
MO0112DQRWLNYE.019, 
MO0111DQRWLNYE.004, 
MO0112DQRWLNYE.021 
5/06/99-12/06/00 
NC-EWDP-9SX probe 2 43-49 767.3 MO0112DQRWLNYE.011, 
MO0112DQRWLNYE.019, 
MO0111DQRWLNYE.004, 
MO0112DQRWLNYE.021 
5/06/99-12/06/00 
NC-EWDP-9SX probe 4 101-104 766.8 MO0112DQRWLNYE.011, 
MO0112DQRWLNYE.019, 
MO0111DQRWLNYE.004, 
MO0112DQRWLNYE.021 
5/06/99-12/06/00 
NC-EWDP-12PA 99-117 722.9 2.2 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.010 
4/18/00-11/15/00

 
 23 
WELL 
OPEN 
INTERVAL 
(m below 
land surface) 
POTENTIOMETRIC 
LEVEL 
(m above sea level) 
HEAD DIFFERENCE 
deepest - shallowest 
intervals (m) 
Source Data REMARKS 
NC-EWDP-12PB 99-117 723.0 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.012 
4/18/00-11/15/00 
NC-EWDP-12PC 52-70 720.7 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.013 
4/27/00-11/15/00 
NC-EWDP-19P 109-140 707.5 5.3 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.014 
3/13/00-6/17/00 
NC-EWDP-19D 106-433 712.8 MO0112DQRWLNYE.025, 
MO0112DQRWLNYE.018 
6/14/00-6/22/00 
Negative value indicates downward gradient

 
 24 
6.2 POTENTIOMETRIC-SURFACE MAP 
For SZ site-scale flow and transport model construction purposes, the potentiometric-surface 
map was created (Figure 6-1) from the water-level data listed in Attachment I, Table I-1. The 
potentiometric contours were hand drawn, rather than computer-generated as in Rev 00 ICN 01 
of this report (USGS 2001). This hand contouring allowed the PI to locate the contours based on 
professional hydrologic judgement and experience. In accordance with the discussion in Section 
5.2, the water-level altitude from the upper interval of each borehole from a site was assumed to 
represent the potentiometric surface. Under this assumption, only water-level altitudes 
representing the uppermost aquifer system, typically the volcanic or alluvial system, were used. 
Fault traces shown on Figure 6-1 represent the mapped surface expression of the faults.

 
 25 
Figure 6-1 Potentiometric-Surface Map, Assuming Perched Conditions North of Yucca Mountain, in the 
SZ Site-Scale Flow and Transport Model Area (Output DTN: GS010608312332.001)

 
 26 
The distribution of water-level data and the complex geology in the SZ site-scale flow and 
transport model area allow for various interpretations of the configuration of the potentiometric 
surface (Luckey et al. 1996, pp. 21-26). Several potentiometric-surface maps (discussed below) 
have been developed that encompass Yucca Mountain and vicinity, including the SZ site-scale 
flow and transport model area and the regional model area. Examination of other potentiometricsurface 
maps that fully or partially cover the SZ site-scale flow and transport model area reveals 
no major differences in the shape of potentiometric-contour lines. This is not unexpected 
because similar, and in some cases the same, water-level data were used to create the 
potentiometric-contour lines; adhering to the rules that govern the construction of potentiometric 
contours, only a limited number of configurations of the water-level data are possible. The 
differences observed between existing potentiometric-surface maps and the one presented in this 
revision can be attributed to map scale, potentiometric-contour intervals, changing concepts of 
potential perched water and the regional potentiometric surface in the large hydraulic gradient 
area, and more and newer water-level data. The potentiometric-surface map created for this 
revision is an accurate interpretation based on the available water-level data, the geologic map of 
the Yucca Mountain region, the assumptions in Section 5, and the regional potentiometric 
surface. 
This analysis differs from that reported in Rev 00 ICN 01 (USGS 2001, Figure 1-2) in several 
ways. The most significant difference is in the portrayal of the large hydraulic gradient (LHG) 
area north of Yucca Mountain. The concept that water levels in boreholes USW G-2 and UE-25 
WT #6 are considered to represent perched conditions (Assumption 5.1.4), is used to create the 
potentiometric surface in this revision. By not using the data from those two boreholes the LHG 
is reduced from about 0.11 (Tucci and Burkhardt 1995, p. 9) to between 0.06 to 0.07, and the 
potentiometric contours are more widely spaced. Another significant difference is that 
potentiometric contours are no longer offset where they cross faults. Such offsets, which were 
shown in the map presented in Rev 00 ICN 01 (USGS 2001, Figure 1-2), would not be expected 
where the contours are perpendicular or nearly perpendicular to the fault trace. Direct evidence 
of offset, which would be provided by wells that straddle the fault, does not exist at Yucca 
Mountain. Faults were used, however, to help in the placement of contours that are oriented 
parallel or approximately parallel to faults. The concept used to represent the impact of faults on 
potentiometric contours is that ground-water flow across a fault (or fault zone) is impeded by the 
fault and ground-water flow parallel to a fault is not impeded by the fault. The basis for this 
representation is discussed in Section 5.2. The contour interval used in this analysis is somewhat 
different from Rev 00 ICN 01 (USGS (2001), which used a uniform contour interval of 25 m 
(USGS 2001, Figure 1-2). The contour interval used in Figure 6-1 is variable, in which the 
interval is 50 m for contours greater than 800 m, and 25 m for contours less than 800 m. Two 
additional contours, 730 and 720 are also included. The inclusion of those contours helps to 
visualize the effect of the fault along Highway 95 (Figure 6-1) , south of Yucca Mountain, on the 
ground-water flow system. 
The potentiometric-surface map presented in Czarnecki et al. (1997, Figure 5) is identical in areal 
extent to the potentiometric-surface map developed for this revision (Figure 6-1). Examination 
of that potentiometric-surface map illustrates an alternative interpretation constructed from 
similar water-level data. Differences in the two maps occur at the boundaries of the maps, where 
there is little or no data; and where the potentiometric surface is influenced by major faults. The

 
 27 
major difference in the shape of the potentiometric contours occurs in the northern and 
northwestern area of the maps. Czarnecki et al. (1997) suggest a closing of the contour lines to 
the north of the LHG, water-level altitudes as much as 150 meters shallower, and an east-west 
trend of the contours in southern Crater Flat. Other major differences occur south of Yucca 
Mountain, because Nye County EWDP data were not available to Czarnecki et al (1997). 
Larger-scale potentiometric-surface maps (Ervin et al. 1994, plate 1; Tucci and Burkhardt 1995, 
Figure 4; Lehman and Brown 1996, Figure 16) cover only a small portion of the site-scale model 
area in the vicinity of Yucca Mountain. The potentiometric-surface map by Ervin et al. (1994, 
plate 1) has water-level contour intervals of 0.25 meters. That map does not attempt to contour 
the areas of the LHG or the moderate hydraulic gradient to the west of the Solitario Canyon fault, 
but the general shape of the potentiometric contours is similar to the map constructed for this 
revision (Figure 6-1). The potentiometric-surface map in Tucci and Burkhardt (1995, Figure 4) 
has contour intervals that are variable, from 0.50 meters to 20.00 meters. Comparing the same 
potentiometric contour (800-meter contour) on that map and the map constructed for this revision 
reveals a similarity in shape, although the gradient in the LHG area in the Tucci and Burkhardt 
(1995) map is larger that the gradient presented in this revision. The map by Lehman and Brown 
(1996, Figure 16) presents an alternate concept of ground-water flow at Yucca Mountain, in 
which faults and fracture zones act as very permeable conduits for flow. Although such features 
play an important role in the ground-water flow system at Yucca Mountain, the map is based on 
corrections to water levels that may not be valid due to the large open intervals in some of the 
wells (Graves et al. 1997, Appendix A). The map that Lehman and Brown present in their report 
(1996, Figure 16) is also somewhat spatially distorted, so that it cannot be directly compared to 
other potentiometric maps constructed for Yucca Mountain. 
The regional potentiometric surface of the Death Valley region (DAgnese et al. 1997, plate 1) is 
at a much smaller scale than the potentiometric-surface map in this revision. The contour 
interval used by DAgnese et al. (1997, plate 1) is 100 meters, resulting in only a few contour 
lines intersecting the SZ site-scale flow and transport model area. As with the larger-scale 
potentiometric-surface maps, the same water-level contours that occur on DAgnese et al. (1997, 
plate 1) and the potentiometric-surface map in this revision can be compared. This comparison 
reveals that the potentiometric contours on both maps are similar, although, because DAgnese et 
al. (1997) assumes that water levels in USW G-2 and UE-25 WT #6 represent regional levels, the 
gradient in the LHG area is larger than the gradient presented in this revision. 
Potentiometric data indicate a complex three-dimensional flow system. Luckey et al. (1996) 
discuss different gradients and interpretations of the SZ site-scale flow and transport model. 
Ground-water flow in the welded volcanic rocks occurs primarily in fractures and secondarily in 
the matrix of the rock (Luckey et al. 1996). Therefore, this flow system may result from the 
presence of faults and associated fracture zones occurring in the welded volcanic hydrogeologic 
units, rather than a system in which ground-water flow is through a porous medium. Depending 
upon where the potentiometric surface is located within the hydrostratigraphic sequence, it may 
be either confined or unconfined. Confined aquifers may exist where a relatively less permeable 
hydrogeologic unit, such as a clay bed or argillic volcanic unit, overlies a permeable 
hydrogeologic unit. An unconfined aquifer has no overlying, relatively less permeable, 
hydrogeologic unit.

 
 28 
Many of the boreholes used in this analysis only partially penetrate a single hydrogeologic unit. 
In boreholes that do penetrate more than one hydrogeologic unit, no attempt was made to 
distinguish water-level measurements associated with specific hydrogeologic units or fracture 
zones. The water-level altitudes in some boreholes represent composite heads from multiple 
hydrogeologic units and fractures zones. Generally, water levels in the uppermost saturated zone 
appear to represent a laterally continuous, well-connected aquifer system (Tucci and Burkhardt 
1995, p. 7). Little impact on the potentiometric surface is expected from boreholes that are open 
at different depth intervals and to different hydrogeologic units. 
Some of the major faults in the region are thought to affect water levels (Ervin et al. 1994; Tucci 
and Burkhardt 1995; Luckey et al. 1996; DAgnese et al. 1997). As a result, several of these 
faults were selected to help interpret the water-level data used in the analysis (Figure 6-1). The 
selection was based on fault displacement of geologic units and extent of the fault, both laterally 
and vertically. The location of some of the major faults may explain the water-level altitudes in 
some of the boreholes and the resulting potentiometric-surface map. For example, an area 
termed the moderate hydraulic gradient is associated with the area adjacent to the Solitario 
Canyon fault, which is located along the west side of Yucca Mountain (approximately parallel to 
the 750-m and 775-m contours shown in Figure 6-1). Water-level altitudes to the west of the 
Solitario Canyon fault are more than 40 meters higher than those to the east (Ervin et al. 1994; 
Tucci and Burkhardt 1995). A moderate to large hydraulic gradient area southwest of Yucca 
Mountain also appears to be related to a fault that is approximately parallel to Highway 95 
(Figure 6-1). 
The potentiometric surface is characterized by four major regions that can be inferred from the 
potentiometric contours depicted in Figure 6-1: 
(1) A small-gradient (0.0001 to 0.0004; Tucci and Burkhardt 1995, p. 9) area to the east and 
southeast of Yucca Mountain where water levels range from about 728 to 732 m. Gradients 
in the Amargosa Desert, south of Yucca Mountain are also small (0.001 to 0.0004; water 
levels ranging from about 720 to about 690 m); 
(2) A moderate-gradient (0.02 to 0.04; Tucci and Burkhardt 1995, p. 9) area to the west of Yucca 
Mountain, where water levels range from about 740 to 800 m, 
(3) A moderate- to large-gradient (0.01 to 0.05) area southwest of Yucca Mountain (along 
Highway 95 near southern Crater Flat), where water levels range from 720 to 775 m, and 
(4) A large-gradient (0.06 to 0.07) area north of Yucca Mountain, where water levels range from 
about 738 to 1188 m. This gradient assumes that water levels in boreholes USW G-2 and 
UE-25 WT #6 represent perched conditions. The hydraulic gradient in the LHG area north of 
Yucca Mountain previously had been reported as about 0.11 (Tucci and Burkhardt 1995, 
p. 9). 
The potentiometric surface presented in this analysis and in previously published reports 
generally implies a hydraulically, well-connected flow system within the uppermost saturated 
zone (Tucci and Burkhardt 1995) as discussed above.

 
 29 
A number of explanations have been proposed to explain the presence of the apparent LHG at the 
north end of Yucca Mountain. Explanations proposed for the LHG include: 
1) Faults that contain nontransmissive fault gouge (Czarnecki and Waddell 1984); 
2) Faults that juxtapose transmissive tuff against nontransmissive tuff (Czarnecki and Waddell 
1984); 
3) The presence of a less fractured lithologic unit (Czarnecki and Waddell 1984); 
4) A change in the direction of the regional stress field and a resultant change in the intensity, 
interconnectedness, and orientation of open fractures on either side of the area with the LHG 
(Czarnecki and Waddell 1984); or 
5) The apparent large gradient actually represents a disconnected, perched- or semi-perchedwater 
body, so that the high water-level altitudes are caused by local hydraulic conditions and 
are not part of the regional saturated-zone flow system (Ervin et al. 1994). 
Fridrich et al. (1994) suggest two hydrogeologic explanations for the LHG: (1) a highly 
permeable buried fault that drains water from the volcanic rock units into a deeper regional 
carbonate aquifer or (2) a buried fault that forms a spill-way in the volcanic rocks. Their 
second explanation, in effect, juxtaposes transmissive tuff against non-transmissive tuff, and is 
therefore the same as (2) above. On a regional basis, other large hydraulic gradient areas are 
associated with a contact in the Paleozoic rocks between clastic, confining unit rocks and the 
regional carbonate aquifer; however, the cause and nature of the LHG near Yucca Mountain is 
not evident.

 
 30 
7. CONCLUSIONS 
7.1 WATER-LEVEL DATA 
Water-level altitudes in the SZ site-scale flow and transport model area range over 400 meters. 
The data distribution generally is very uneven, and the hydraulic character of the formations and 
the location of recharge areas, both of which influence the water level, are variable. As a result, 
water levels vary significantly over the SZ site-scale flow and transport model area. 
Most of the water levels used in this analysis are composite levels in which water is produced 
from one or more hydrogeologic units or fracture zones as indicated in Attachment I, Table I-5, 
of this revision. Because of long open (uncased) or perforated/screened intervals, many boreholes 
intercept multiple permeable zones, resulting in a composite water-level altitude. 
Potential errors in the potentiometric surface can result from the use of data from wells 
completed in potentially perched-water bodies, and from inaccuracies in the borehole sitelocation, 
land-surface altitude, water-level measurements, and water-level altitude calculation. 
Evaluation of methodology accuracy is documented in Attachment I, Tables I-6, I-7, and I-8. 
This information may be used to evaluate the representativeness of the water-level altitudes used 
in this analysis and to determine whether or not these altitudes represent the potentiometric 
surface of the upper saturated zone. 
In addition to measurement uncertainties, the range in water levels for a borehole can be used in 
the determination of an uncertainty of a mean water level at that site. Pumping is included in the 
flux rates used in the regional model (DAgnese et al. 1997); therefore water levels that may be 
influenced by pumping are included in the SZ site-scale flow and transport model (CRWMS 
M&O 2000). Because of the uncertainties in water levels discussed in the previous paragraph, 
the range in water-level altitudes and the possible causes of that variability should be taken into 
account during SZ site-scale flow and transport model calibration. 
7.1.1 Vertical Head Differences 
Vertical head differences, documented in Table 6-1, are variable throughout the SZ site-saturated 
zone model area. Of the 17 sites at which vertical gradients have been evaluated, most gradients 
(12) are upward, and fewer (5) are downward. No correlation is evident in the spatial location of 
boreholes and the location of upward or downward vertical gradients. The reason for this lack of 
spatial correlation probably is because of the wide variation in the monitored hydrogeologic units 
and depths of the monitored intervals. Gradients appear to be upward from the Paleozoic 
carbonate aquifer and from the deepest parts of the volcanic-rock aquifers, where potentiometric 
levels may be influenced by the underlying carbonates. A significant downward gradient exists 
at borehole NC-EWDP-1DX at a paleospring deposit south of Crater Flat. A slight downward 
gradient at borehole UE-25 J-13 may be indicative of recharge to the ground-water system along 
Fortymile Wash; however, the gradient is so small that it might only be an artifact of errors in 
water-level measurements.

 
 31 
7.2 POTENTIOMETRIC-SURFACE MAP 
The potentiometric surface shown in Figure 6-1 provides a contour-map representation of the 
potentiometric surface from water-level data that were developed for this report and that are 
available from the TDMS under DTN: GS010608312332.001. This revised potentiometric 
surface presents an alternate concept of the LHG area north of Yucca Mountain to that presented 
in Rev 00 ICN 01 (USGS 2001). In this revision, water levels in boreholes USW G-2 and UE-25 
WT #6 are assumed to represent perched conditions and not regional potentiometric levels. If 
perched conditions do not actually exist at those boreholes, and the water level in USW WT-24 
also represents the regional potentiometric level, then the hydraulic gradient north of Yucca 
Mountain would be much greater than previously reported . 
The potentiometric surface developed from the input data sets listed in Table 4-1 incorporates the 
potential errors and uncertainties identified in this revision. Hence, the accuracy of the 
potentiometric surface will vary spatially. In the potential repository area, the potentiometric 
surface may be characterized within one meter; however, in other areas within the SZ site-scale 
flow and transport model area the uncertainty in water levels is much greater because of lack of 
data in many areas. Areas where perched-water zones may exist, water-level drawdown 
associated with pumping in the Amargosa Valley, and the unknown effect of faults on waterlevel 
altitudes all add to the uncertainty of the accuracy of the potentiometric surface constructed 
using these data. The potentiometric surface presented herein does not strictly represent the water 
table, a concept reserved for the actual interface between the saturated and unsaturated zones. 
However, the potentiometric surface presented is probably a close and reasonable representation 
of the water table for the early 1990s (see Assumption 1 in Section 5.1). 
Large portions of the SZ site-scale flow and transport model area contain no water-level data, and 
potentiometric contours drawn through those areas (indicated by dashed contours on Figure 6-1) 
are speculative and subject to other equally valid interpretations. Potential errors in the location 
of those contours will be represented in the site-scale SZ model as potential errors in the 
saturated thickness of the uppermost saturated unit or by a difference in which geologic unit 
constitutes the uppermost saturated unit.

 
 32 
8. INPUTS AND REFERENCES 
8.1 DOCUMENTS CITED 
BSC (Bechtel SAIC Company) 2001. Technical Work Plan for Saturated Zone Flow and 
Transport Modeling and Testing. TWP-NBS-MD-000001 REV 02. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: MOL.20010924.0269. 
CRWMS M&O 2000. Calibration of the Site-Scale Saturated Zone Flow Model. MDL-NBS-HS- 
000011 REV 00. Las Vegas, Nevada: CRWMS M&O. ACC: MOL.20000825.0122 
CRWMS M&O 2001. Repository Safety Strategy: Plan to Prepare the Safety Case to Support 
Yucca Mountain Site Recommendation and Licensing Considerations. TDR-WIS-RL-000001 
REV 04 ICN 01. Two volumes. Las Vegas, Nevada: CRWMS M&O. ACC: 
MOL.20010329.0825. 
Czarnecki, J.B. and Waddell, R.K. 1984. Finite-Element Simulation of Ground-Water Flow in 
the Vicinity of Yucca Mountain, Nevada-California. Water-Resources Investigations Report 84- 
4349. Denver, Colorado: U.S. Geological Survey. ACC: NNA.19870407.0173. 
Czarnecki, J.B.; Faunt, C.C.; Gable, C.W.; and Zyvoloski, G.A. 1997. Hydrogeology and 
Preliminary Three-Dimensional Finite-Element Ground-Water Flow Model of the Site Saturated 
Zone, Yucca Mountain, Nevada. Milestone SP23NM3. Denver, Colorado: U.S. Geological 
Survey. ACC: MOL.19990812.0180. 
DAgnese, F.A.; Faunt, C.C.; Turner, A.K.; and Hill, M.C. 1997. Hydrogeologic Evaluation and 
Numerical Simulation of the Death Valley Regional Ground-Water Flow System, Nevada and 
California. Water-Resources Investigations Report 96-4300. Denver, Colorado: U.S. Geological 
Survey. ACC: MOL.19980306.0253. 
DOE (U.S. Department of Energy) 2000. Quality Assurance Requirements and Description. 
DOE/RW-0333P, Rev. 10. Washington, D.C.: U.S. Department of Energy, Office of Civilian 
Radioactive Waste Management. ACC: MOL.20000427.0422. 
Ervin, E.M.; Luckey, R.R.; and Burkhardt, D.J. 1994. Revised Potentiometric-Surface Map, 
Yucca Mountain and Vicinity, Nevada. Water-Resources Investigations Report 93-4000. Denver, 
Colorado: U.S. Geological Survey. ACC: NNA.19930212.0018. 
Freeze, R.A. and Cherry, J.A. 1979. Groundwater. Englewood Cliffs, New Jersey: Prentice-Hall. 
TIC: 217571. 
Fridrich, C.J.; Dudley, W.W., Jr.; and Stuckless, J.S. 1994. Hydrogeologic Analysis of the 
Saturated-Zone Ground-Water System, Under Yucca Mountain, Nevada. Journal of Hydrology, 
154, 133-168. Amsterdam, The Netherlands: Elsevier Science B.V. TIC: 224606.

 
 33 
Graves, R.P.; Tucci, P.; and OBrien, G.M. 1997. Analysis of Water-Level Data in the Yucca 
Mountain Area, Nevada, 1985-95. Water-Resources Investigations Report 96-4256. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.19980219.0851. 
Graves, R.P., 1998. Water Levels in the Yucca Mountain Area, Nevada, 1996. Open-File Report 
98-169. Denver, Colorado: U.S. Geological Survey. ACC: MOL.19981117.0340. 
Graves, R.P. 2001. "Re: WT-24." E-mail from R.P. Graves (USGS) to P. Tucci (USGS), August 
29, 2001. ACC: MOL.20010907.0002. 
Lehman, L.L. and Brown, T.P. 1996. Summary of State of Nevada - Funded Studies of the 
Saturated Zone at Yucca Mountain, Nevada, Performed by L. Lehman & Associates, Inc. 
Burnsville, Minnesota: L. Lehman and Associates. TIC: 231894. 
Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M.; Steinkampf, W.C.; DAgnese, F.A.; and 
Patterson, G.L. 1996. Status of Understanding of the Saturated-Zone Ground-Water Flow System 
at Yucca Mountain, Nevada, as of 1995. Water-Resources Investigations Report 96-4077. 
Denver, Colorado: U.S. Geological Survey. ACC: MOL.19970513.0209. 
OBrien, G. 1998. Milestone SPH40NM4 (Level 4)  Memo to TPO: Possible Perched-Water 
Occurrences North of Yucca Mountain. Memorandum from G. OBrien (USGS) to R. Craig 
(USGS), September 28, 1998, with attachment, Perched-Water Analysis Death Valley Region. 
ACC: MOL.19981130.0221; MOL.19990113.0213. 
Spengler, R. 2001. Pz in NC-EWDP-2DB. E-mail from R. Spengler (USGS) to P. McKinley, 
August 30, 2001 ACC: MOL.20010907.0001. 
Tucci, P. and Burkhardt, D.J. 1995. Potentiometric-Surface Map, 1993, Yucca Mountain and 
Vicinity, Nevada. Water-Resources Investigations Report 95-4149. Denver, Colorado: U.S. 
Geological Survey. ACC: MOL.19960924.0517. 
Tucci, P. 2001. Segment of SN-USGS-SCI-126-V1: Revision of Water Level AMR (ANL-NBSHS-
000034, Rev 00/ICN 01). Scientific Notebook SN-USGS-SCI-126-V1. ACC: 
MOL.20010712.0271. 
USGS (U.S. Geological Survey) 2000. Water Level Data Analysis for SZ Site-Scale Model. 
Development Plan TDP-NBS-HS-000099 REV 00. [Denver, Colorado]: U.S. Geological 
Survey. ACC: MOL.20000630.0045. 
USGS 2001. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport 
Model. ANL-NBS-HS-000034 REV 00 ICN 01. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.20010405.0211. 
8.2 STANDARDS, REGULATIONS, PLANS, AND PROCEDURES CITED 
66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic Repository at 
Yucca Mountain, NV. Final Rule 10 CFR Part 63. Readily available.

 
 34 
AP-2.13Q, Rev. 0, ICN 4. Technical Product Development Planning. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20000620.0067. 
AP-2.21Q, Rev. 1. Quality Determinations and Planning for Scientific, Engineering, and 
Regulatory Compliance Activities. Washington, D.C.; U.S. Department of Energy, Office of 
Civilian Radioactive Waste Management. ACC: MOL. 20010212.0018. 
AP-3.10Q, Rev. 2, ICN 5. Analyses and Models. Washington, D. C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: MOL.20011126.0261. 
AP-3.15Q, Rev. 3, ICN 0. Managing Technical Product Inputs. Washington, D. C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20010801.0318. 
AP-SI.1Q, Rev. 3, ICN 2, ECN 1 Software Management. Washington, D.C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. ACC: MOL.20011030.0598. 
AP-SV.1Q, Rev. 0, ICN 2. Control of Electronic Management of Information. Washington, 
D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste Management. ACC: 
MOL.20000831.0065. 
8.3 SOFTWARE PROGRAMS 
U.S. Geological Survey 2000. Software Code: ARCINFO. V7.2.1. 10033-7.2.1-01. 
8.4 SOURCE DATA, LISTED BY DATA TRACKING NUMBER 
GS000400002332.001. Digital Elevation Models Death Valley East Scale 1:250,000. Submittal 
date: 04/12/2000. 
GS000408312312.001. Water-Level Measurements at UE-25 C #2 and C #3, 1989. Submittal 
date: 04/10/2000. 
GS000608312312.003. Water-Level Altitude Data from the Periodic Network, January 1999 
through March 1999. Submittal date: 07/10/2000. 
GS000608312312.004. Revised Water-Level Altitude Data from the Periodic Network, First 
Quarter 1995. Submittal date: 06/27/2000. 
GS000708312312.005. Water-Level Altitude Data, 1993. Submittal date: 07/10/2000. 
GS000808312312.007. Ground-Water Altitudes from Manual Depth-to-Water Measurements at 
Various Boreholes November 1998 through December 1999. Submittal date: 08/21/2000. 
GS920408312314.009. Geohydrology of Rocks Penetrated by Test Well UE-25 p#1 (UE-25 
p#1), Yucca Mountain Area, Nye County, Nevada. Submittal date: 04/27/1992.

 
 35 
GS930408312132.007. Geohydrologic Data and Test Results from Well J-13, Nevada Test Site, 
Nye County, Nevada. Submittal date: 04/23/1993. 
GS930408312312.015. Water Levels in the Yucca Mountain Area, Nevada, 1990-91. Submittal 
date: 04/28/1993. 
GS931008312312.025. Water Levels in Periodically Measured Wells in the Yucca Mountain 
Area, Nevada, 1981-87. Submittal date: 04/23/1993. 
GS950108312312.001. Water-Level Altitude Data from the Periodic Network Fourth Quarter 
1994. Submittal date: 01/19/1995. 
GS950508312312.005. Potentiometric-Surface Map, 1993, Yucca Mountain and Vicinity, 
Nevada. Submittal date: 06/06/1995. 
GS960208312312.003. 28 Water-Level Measurements from the Periodic Network, Third 
Quarter, 1995 (7/1/95 - 9/30/95). Submittal date: 02/20/1996. 
GS960908312312.010. Analysis of Water-Level Data in the Yucca Mountain Area, Nevada, 
1985-1995. Submittal date: 09/19/1996. 
GS970600012847.001. Water Level Altitude Data Collected at GEXA Well 4 and USW G-4. 
Submittal date: 06/30/1997. 
GS980308312312.004. Water Levels in the Yucca Mountain Area, Nevada, 1996. Submittal 
date: 03/31/1998. 
GS990908312312.005. Water-Level Altitude Data, April - June 1999. Submittal date: 
09/20/1999. 
GS991100002330.001. Water Level Data for Yucca Mountain Region and Amargosa Desert. 
Submittal date: 03/29/2000. 
GS991208314221.001. Geologic Map of the Yucca Mountain Region. Submittal date: 
12/01/1999. 
MO0008WTRALTG4.000. Water-Table-Altitude Data for Well USW G-4, Yucca Mountain 
Area, Nye County, Nevada. Submittal date: 08/24/2000. 
MO0011ELLOCAMD.000. Locations and Elevations for Selected Wells in the Yucca Mountain 
Region and Amargosa Desert from the USGS NWIS Database. Submitted date: 11/06/2000. 
MO0103COV01031.000. Coverage: BORES3Q. Submittal date: 03/22/2001. 
MO0107COV01057.000. Coverage: NCEWDPS. Submittal date: 07/18/2001. 
MO0111DQRWLNYE.002. Water Level Data From Westbay Instrumented Borehole NCEWDP-
1S. Submittal date: 11/29/2001.

 
 36 
MO0111DQRWLNYE.003. Water Level Data From Westbay Instrumented Borehole NCEWDP-
3S. Submittal date: 11/29/2001. 
MO0111DQRWLNYE.004. Water Level Data From Westbay Instrumented Borehole NCEWDP-
9SX. Submittal date: 11/29/2001. 
MO0112DQRWLNYE.005. Well Completetion Diagram For Borehole NC-EWDP-4PA. 
Submittal date: 12/03/2001. 
MO0112DQRWLNYE.006. Well Completion Diagram For Borehole NC-EWDP-4PB. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.007. Well Completion Diagram For Borehole NC-EWDP-7S. Submittal 
date: 12/04/2001. 
MO0112DQRWLNYE.008. Well Completion Diagram For Borehole NC-EWDP-5SB. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.009. Well Completion Diagram For Borehole NC-EWDP-15P. Submittal 
date: 12/04/2001. 
MO0112DQRWLNYE.010. Well Completion Diagram For Borehole NC-EWDP-12PA. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.011. Well Completion Diagram For Borehole NC-EWDP-9SX. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.012. Well Completion Diagram For Borehole NC-EWDP-12PB. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.013. Well Completion Diagram For Borehole NC-EWDP-12PC. 
Submittal date: 12/04/2001. 
MO0112DQRWLNYE.014. Well Completion Diagram For Borehole NC-EWDP-19P. Submittal 
date: 12/04/2001. 
MO0112DQRWLNYE.015. Well Completion Diagram For Borehole NC-EWDP-3S. Submittal 
date: 12/04/2001. 
MO0112DQRWLNYE.016. Well Completion Diagram For Borehole NC-EWDP-3D. Submittal 
date: 12/04/2001. 
MO0112DQRWLNYE.017. Well Completion Diagram For Borehole NC-EWDP-1DX. 
Submittal date: 12/05/2001. 
MO0112DQRWLNYE.018. Well Completion Diagram For Borehole NC-EWDP-19D. 
Submittal date: 12/05/2001.

 
 37 
MO0112DQRWLNYE.019. Multi-Level Monitoring Port Depths In Nye County Boreholes NCEWDP-
1S, -3S AND -9SX. Submittal date: 12/05/2001. 
MO0112DQRWLNYE.020. Water Level Depth Data For Nye County Boreholes NC-EWDP-2D 
AND -2DB. Submittal date: 12/05/2001. 
MO0112DQRWLNYE.021. Multilevel Piezometer Casing Log For Borehole NC-EWDP-9SX. 
Submittal date: 12/05/2001. 
MO0112DQRWLNYE.022. Multilevel Piezometer Casing Log For Borehole NC-EWDP-3S. 
Submittal date: 12/05/2001. 
MO0112DQRWLNYE.023. Multilevel Piezometer Casing Log For Borehole NC-EWDP-1S. 
Submittal date: 12/05/2001. 
MO0112DQRWLNYE.024. EWDP Phase I Manual Water Level Measurements. Submittal date: 
12/06/2001. 
MO0112DQRWLNYE.025. EWDP Phase II Manual Water Level Measurements. Submittal 
date: 12/06/2001. 
TM0000000SD7RS.003. USW SD-7 Shift Drilling Summaries (1602.0'-2020.3'), Lithologic 
Logs (1600.0'-1925.0'), and Structure Logs (1632.0'-2020.3'). Submittal date: 09/22/1995. 
TM0000000SD9RS.001. USW SD-9 Shift Drilling Summaries, Structural Logs, and Lithological 
Logs. Submittal date: 08/23/1994. 
TM000000SD12RS.011. USW SD-12 Shift Drilling Summaries, Lithologic Logs, and Structure 
Logs from 1825.0'-2166.3'. Submittal date: 09/08/1995. 
8.5 AMR OUTPUT DATA, LISTED BY DATA TRACKING NUMBER 
GS010608312332.001 Potentiometric-Surface Map, assuming perched conditions north of Yucca 
Mountain, in the Saturated Zone Site-Scale Flow and Transport Model Area. Submittal date: 
6/18/2001. 
GS010908312332.002. Borehole Data from Water-Level Data Analysis for the Saturated Zone 
Site-Scale Flow and Transport Model. Submittal date: 09/28/2001. 
GS010908312332.003. Vertical Head Differences from Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model. Submittal date: 09/28/2001.

 I-1 
ATTACHMENT I 
BOREHOLE DATA 
TOTAL PAGES: 31

 
 I-2 
The following sections describe the information pertaining to terms used in Attachment I. 
USGS Site Identification 
Unique site identifications (IDs) are assigned to each borehole for which the USGS maintains water-level data. 
Boreholes that contain multiple monitoring zones are assigned a unique site ID for each of the different zones. The 
site IDs are different than the site ID for the entire borehole, but usually contain a portion of the borehole site ID. 
Where more than one site ID for a given borehole exists (multiple monitoring zones), the site ID for the entire 
borehole is used in Attachment I. 
Site Name 
The common borehole site name available for a given site was recorded. 
CONTENTS 
Table I-1 Easting, Northing, Land Surface Altitude, Mean Water-level Altitude (DTN: 
GS010908312332.002)............................................................................................. I-3 
Table I-2 Number of Data Points Used, Source, and Use ........................................................ I-7 
Table I-3 Reliability of Measurements................................................................................... I-12 
Table I-4 Earliest Year of Measurement, Latest Year of Measurement, Minimum Waterlevel 
Altitude, and Maximum Water-level Altitude (DTN: 
GS010908312332.002)........................................................................................... I-15 
Table I-5 Top of Interval, Bottom of Interval, and Midpoint of Interval ............................... I-19 
Table I-6 Interval Description and Accuracy of Location...................................................... I-23 
Table I-7 Accuracy of Land-surface Altitude and Latest Water-level Measurement 
Method Description ................................................................................................ I-26 
Table I-8 Water Level Measurement Accuracy and Perched?............................................... I-29

 
 I-3 
Table I-1 Easting, Northing, Land Surface Altitude, Mean Water-level Altitude (DTN: GS010908312332.002) 
Easting and Northing 
Coordinates for boreholes used in this analysis are from DTNs MO0011ELLOCAMD.000 (see Assumption 5.3), 
MO0103COV01031.000, and MO0107COV01057.000,. UTM easting and northing were calculated using ARCINFO PROJECT 
command. The latitude/longitude, or state plane coordinate, was projected into UTM (meters, Zone 11, North American Datum 
1927) coordinates and rounded to the nearest meter. 
Land-surface Altitude Above Sea Level (meters) 
The land-surface altitudes for boreholes used in this analysis are from DTNs MO0011ELLOCAMD.000 (see Assumption 5.3), 
MO0107COV01057.000, and MO0103COV01031.000. The altitude was converted from feet to meters by the following 
formula, where necessary: 
Altitude (ft) x 0.3048 (m/ft) = Altitude (m) 
For example: 2401.52 ft x 0.3048 m/ft = 731.98 m 
The altitude was subsequently rounded to the nearest tenth of a meter for use in this table. 
Mean Water-level Altitude Above Sea Level (meters) 
Mean water-level altitudes were calculated as time-averages over the period of available measurements. For the wells tabulated 
in Graves et al. (1997, Table 2, DTN: GS960908312312.010), monthly mean water-level altitudes computed from hourly 
transducer data and periodic manual water-level altitude measurements were used to compute the mean water-level altitude. The 
mean water level for each site not included in Graves et al. (1997, DTN: GS960908312312.010) was calculated based on the 
available record. An example calculation follows: 
(730.98+731.07+731.09)/3 = 731.05 
The altitude was subsequently rounded to the nearest tenth of a meter for use in this table. 
In addition, the following exceptions were made when calculating the mean: 
 NDOT well: Deleted the 1972 measurement (2,291.8 ft) from the calculation of the average. It is anomalously low and 
not representative of average conditions in the borehole. 
 Donald O. Heath well: Deleted the 1961 measurement (2,342.0 ft) from the calculation of the average. It is 
anomalously high and not representative of average conditions in the borehole. 
 William R. Monroe well: Deleted the 1958 measurement (2,362.0 ft) from the calculation of the average. It is 
anomalously high and not representative of average conditions in the borehole. 
 Cooks West well: Deleted the 1963 measurement (2,324.6 ft) from the calculation of the average. It is anomalously 
low and not representative of average conditions in the borehole. 
 Cooks East well: Deleted the 2 measurements of 2,333.8 ft (12/20/1961) and 2,335.3 ft(04/09/1991) from the 
calculation of the average. They are anomalously low and not representative of average conditions in the borehole. 
 DeFir well: Used the data obtained after 1982 as being more representative of the calibration period. 
 Airport well: Deleted the 1964 measurement (2,348.8 ft) from the calculation of the average. It is anomalously high 
and not representative of average conditions in the borehole. 
 GEXA Well 4: Deleted 1991 measurement (3133.2 ft.) from the calculations of the average. It is anomalously low and 
not representative of average conditions in the borehole. 
 Nye County EWDP boreholes: Water-level measurements made prior to development of the well were not used to 
calculate the mean. Additionally, water-level measurements obtained by transducers that were believed to be 
unreliable (based on comparison to measurements in other zones within the borehole and/or comparison to other 
boreholes) were not used. Those individual unreliable measurements consist of thousands of data points and are too 
numerous to list here. 
.

 
 I-4 
USGS Site ID Site Name Easting 
(UTM) 
Northing 
(UTM) 
Land-surface 
Altitude 
(m) 
Mean Waterlevel 
Altitude 
(m) 
365629116222602 UE-29 a #2 555753 4088351 1215.4 1187.7 
365520116370301 GEXA Well 4 534069 4086110 1198.1 1009.0 
365340116264601 UE-25 WT #6 549352 4083103 1314.8 1034.6 
365322116273501 USW G-2 548143 4082542 1554.0 1020.2 
365239116253401 UE-25 WT #16 551146 4081234 1210.9 738.3 
365208116274001 USW UZ-14 548032 4080260 1348.9 779.0 
365207116264201 UE-25 WT #18 549468 4080238 1336.4 730.8 
365200116272901 USW G-1 548306 4080016 1325.9 754.2 
365147116185301 UE-25 a #3 561084 4079697 1385.6 748.3 
365140116260301 UE-25 WT #4 550439 4079412 1169.3 730.8 
365116116233801 UE-25 WT #15 554034 4078694 1083.2 729.2 
365114116270401 USW G-4 548933 4078602 1269.5 730.6 
365105116262401 UE-25 a #1 549925 4078330 1199.2 731.0 
365032116243501 UE-25 WT #14 552630 4077330 1076.4 729.7 
365023116271801 USW WT-2 548595 4077028 1301.4 730.6 
364947116254300 UE-25 c #1 550955 4075933 1130.6 730.2 
364947116254501 UE-25 c #3 550930 4075902 1132.4 730.2 
364947116254401 UE-25 c #2 550955 4075871 1132.2 730.2 
364945116235001 UE-25 WT #13 553730 4075827 1032.5 729.1 
364933116285701 USW WT- 7 546151 4075474 1196.9 775.8 
364916116265601 USW WT- 1 549152 4074967 1201.4 730.4 
364905116280101 USW G-3 547543 4074619 1480.6 730.5 
364828116234001 UE-25 J -13 554017 4073517 1011.3 728.4 
364825116290501 USW WT-10 545964 4073378 1123.4 776.0 
364822116262601 UE-25 WT #17 549905 4073307 1124.0 729.7 
365821116343701 USW VH-2 537738 4073214 974.5 810.4 
364757116245801 UE-25 WT #3 552090 4072550 1030.0 729.6 
364732116330701 USW VH-1 539976 4071714 963.5 779.4 
364656116261601 UE-25 WT #12 550168 4070659 1074.7 729.5 
364649116280201 USW WT-11 547542 4070428 1094.1 730.7 
364554116232400 UE-25 J -12 554444 4068774 953.6 727.9 
364528116232201 UE-25 JF #3 554498 4067974 944.4 727.8 
364105116302601 Cind-R-Lite Well 544027 4059809 830.8 729.8 
363907116235701 Ben Bossingham 553704 4056228 819.9 718.4 
363836116234001 Fred Cobb 553808 4055459 811.4 702.8 
363840116235000 Bob Whellock 553883 4055398 813.8 704.1 
363840116234001 Louise Pereidra 554131 4055399 810.8 705.6 
363840116233501 Joe Richards 554008 4055337 811.4 701.6 
363835116234001 NDOT Well 553685 4055242 809.8 705.4 
363742116263201 James H. Shaw 549863 4054911 795.5 706.7 
363830116241401 Airport Well 552818 4054929 804.3 705.3 
363815116175901 TW- 5 562604 4054686 931.5 725.1 
363711116263701 Richard Washburn 549746 4053647 783.9 707.7 
363621116263201 Richard Washburn 549679 4052322 774.2 704.4 
363549116305001 Nye County Development Co 543481 4050069 742.2 694.3 
363523116353701 Fred Wooldridge 536350 4050006 731.8 691.9 
363525116325601 Fred J. Keefe 540673 4049994 735.2 694.3

 
 I-5 
USGS Site ID Site Name Easting 
(UTM) 
Northing 
(UTM) 
Land-surface 
Altitude 
(m) 
Mean Waterlevel 
Altitude 
(m) 
363519116322001 Leslie Nickels 541518 4049937 737.0 694.3 
363540116240801 L. Mason 553471 4049848 771.1 722.1 
363527116292501 Unknown 545596 4049403 744.0 697.8 
363521116352501 Davidson Well 536552 4049329 730.1 690.1 
363456116335501 Eugene J. Mankinen 538889 4049000 740.7 707.4 
363454116314201 Donald O. Heath 542194 4048892 733.7 694.1 
363503116351501 Elvis Kelley 536903 4048621 727.9 691.0 
363503116284001 Manuel Rodela 546718 4048669 740.7 693.6 
363436116342301 Charles C. DeFir Jr. 538196 4048442 740.7 706.9 
363436116333201 William R. Monroe 540035 4048450 731.5 693.7 
363434116354001 DeFir Well 536655 4048405 727.1 690.2 
363438116324601 Edwin H. Mankinen 540608 4048083 727.9 695.2 
363442116363301 Bill Strickland 534967 4047966 725.7 689.2 
363440116282401 M. Meese 547120 4047963 731.5 686.4 
363415116275101 Theo E. Selbach 547941 4047782 741.9 696.2 
363407116342501 C.L. Caldwell 537727 4047670 723.3 691.4 
363407116243501 Leonard Siegel 552390 4047685 762.0 709.0 
363429116315901 James K. Pierce 541778 4047596 729.1 690.4 
363405116321501 James K. Pierce 541381 4047563 740.7 705.6 
363428116240301 Cooks West Well 553609 4047631 754.3 720.1 
363428116234701 Cooks East Well 554006 4047633 755.2 718.9 
363417116271801 Nye County Land Company 548466 4047261 740.7 690.1 
363411116272901 Amargosa Town Complex 548492 4047077 739.1 688.8 
363410116261101 Nye County Development Co 550431 4047057 743.7 691.2 
363410116240301 Lewis C. Cook 553612 4047076 748.6 717.4 
363410116240001 Lewis C. Cook 553687 4047077 749.8 714.8 
363407116273301 Amargosa Valley Water 548393 4046953 737.9 701.3 
363342116335701 Earl N. Selbach 539147 4046844 723.9 696.5 
363340116332901 Lewis N. Dansby 539968 4046817 724.2 694.2 
363342116325101 Edwin H. Mankinen 540788 4046821 724.2 694.0 
363350116252101 Willard Johns 552097 4046882 746.8 699.5 
365157116271202 USW H-1 tube 1 548727 4079926 1303.0 785.5 
365157116271203 USW H-1 tube 2 548727 4079926 1303.0 736.0 
365157116271204 USW H-1 tube 3 548727 4079926 1303.0 730.6 
365157116271205 USW H-1 tube 4 548727 4079926 1303.0 730.8 
365122116275502 USW H-5 upper 547668 4078841 1478.9 775.5 
365122116275503 USW H-5 lower 547668 4078841 1478.9 775.6 
365108116262302 UE-25 b #1 lower 549949 4078423 1200.7 729.7 
365108116262303 UE-25 b #1 upper 549949 4078423 1200.7 730.6 
365049116285502 USW H-6 upper 546188 4077816 1301.8 776.0 
365049116285505 USW H-6 lower 546188 4077816 1301.8 775.9 
365032116265402 USW H-4 upper 549188 4077309 1248.5 730.4 
365032116265403 USW H-4 lower 549188 4077309 1248.5 730.5 
364942116280002 USW H-3 upper 547562 4075759 1483.2 731.5 
364942116280003 USW H-3 lower 547562 4075759 1483.2 755.9 
364938116252102 UE-25 p #1 (Lwr Intrvl) 551501 4075659 1114.2 752.4 
not available yet USW SD-7 548384 4076499 1363.1 727.6 
not available yet USW SD-9 548550 4079256 1303.4 731.1

 
 I-6 
USGS Site ID Site Name Easting 
(UTM) 
Northing 
(UTM) 
Land-surface 
Altitude 
(m) 
Mean Waterlevel 
Altitude 
(m) 
not available yet USW SD-12 548492 4077415 1323.7 730.0 
364234116351501 NC-EWDP-1DX, deep zone 536768 4062502 803.6 748.8 
364234116351501 NC-EWDP-1DX, shallow zone 536768 4062502 803.6 786.8 
364233116351501 NC-EWDP-1S, probe 1 536771 4062498 803.8 787.1 
364233116351501 NC-EWDP-1S, probe 2 536771 4062498 803.8 786.8 
363940116275501 NC-EWDP-2DB 547800 4057195 801.3 713.7 
363939116275401 NC-EWDP-2D 547744 4057164 801.2 706.1 
364054116321401 NC-EWDP-3D 541273 4059444 799.4 718.3 
364054116321301 NC-EWDP-3S, probe 2 541269 4059445 798.8 719.8 
364054116321301 NC-EWDP-3S, probe 3 541269 4059445 798.8 719.4 
364012116223401 NC-EWDP-5SB 555676 4058229 840.3 723.6 
364145116334401 NC-EWDP-9SX, probe 1 539039 4061004 797.3 766.7 
364145116334401 NC-EWDP-9SX, probe 2 539039 4061004 797.3 767.3 
364145116334401 NC-EWDP-9SX, probe 4 539039 4061004 797.3 766.8 
363951116252401 NC-Washburn-1X 551465 4057563 824.1 714.6 
363925116241501 NC-EWDP-4PA 553167 4056766 823.0 717.9 
363925116241401 NC-EWDP-4PB 553167 4056766 823.2 723.6 
364332116332201 NC-EWDP-7S 539638 4064323 836.9 830.1 
364137116351001 NC-EWDP-12PA 536951 4060814 774.7 722.9 
364138116351001 NC-EWDP-12PB 536951 4060814 774.7 723.0 
364139116351001 NC-EWDP-12PC 536951 4060814 774.5 720.7 
364011116294901 NC-EWDP-15P 544848 4058158 786.9 722.5 
364015116265301 NC-EWDP-19P 549329 4058292 819.2 707.5 
364014116265301 NC-EWDP-19D 549317 4058270 819.2 712.8 
365301116271301 USW WT-24 548697 4081909 1493.6 840.1 
364706116170601 UE-25 J -11 563799 4071058 1049.5 732.2 
364237116365401 BGMW-11 534386 4062600 787.9 715.9 
363709116264601 Richard Washburn 549529 4052567 775.7 704.0 
363409116233701 L. Cook 551348 4047432 755.9 713.2 
363411116264701 Unknown 549532 4047668 745.2 689.5 
363428116281201 Amargosa Water 547420 4047594 738.2 690.4 
363429116233401 Lewis C. Cook 554329 4047666 755.3 715.7 
363511116335101 Unknown 538989 4048877 729.4 690.8 
365624116222901 USW UZ-N91 555680 4088196 1203.0 1186.7

 
 I-7 
Table I-2 Number of Data Points Used, Source, and Use 
Number of Data Points Used 
The number of data points used to determine the mean in Table I-1. 
Source 
The Data Tracking Number for the source from which the water-level data used to determine the mean (Table I-1) and minimum 
and maximum (Table I-4) water level altitude. 
Use 
The most appropriate use for each water level was identified as: 
Potentiometric-surface map and calibration (WT) 
Calibration (C) 
Assumed to be perched (P). These water-level observations are not considered in construction of the potentiometric surface map 
nor considered as calibration points. 
Unreliable (U) and therefore not used in the construction of the potentiometric-surface map. These water-level observations are 
not recommended for use in SZ site-scale model calibration. 
A water-level measurement was identified as applicable for potentiometric-surface map construction if it was: 
The water level from the upper interval (or only interval) from a borehole. 
The water-level interval in the shallow (uppermost) aquifer system, typically the volcanic- or alluvial-aquifer system. 
A water-level measurement was identified as unreliable on the basis of the criteria listed in Table I-3. In addition, the following 
boreholes contained in Attachment I were excluded from this analysis for the reasons stated below: 
 Two Lewis C. Cook boreholes ( ID numbers 363410116240001 and 363410116240301): The data for these boreholes 
consist of two water-level measurements in each borehole that span more than 20 years and differ by quite a bit. An 
average of the two values for each of these boreholes does not produce a water level that is representative of the early 
1990's. The average is considered Unreliable. There are other boreholes nearby that have reliable water levels that 
are sufficient for the SZ site-scale modeling. 
 Fred Cobb well: Basically similar arguments apply as for the Lewis C. Cook boreholes. Water-level data from this 
borehole are not critical for model calibration because there are other boreholes nearby that have reliable water levels. 
 Fred Woolridge well: Similar arguments apply as for the Lewis C. Cook boreholes. Water-level data from this borehole 
are not critical for model calibration because there are other boreholes nearby that have reliable water levels. 
The remaining water-level data were labeled as suitable for calibration only. Calibration of the SZ site-scale model should be 
based on all water-level data except those labeled as unreliable (U). 
USGS Site ID Site Name 
Number of 
Data Points 
Used 
Source Use 
365629116222602 UE-29 a #2 208 GS991100002330.001 WT 
365520116370301 GEXA Well 4 52 GS991100002330.001 WT 
365340116264601 UE-25 WT #6 117 GS960908312312.010 P 
365322116273501 USW G-2 28 GS960908312312.010 P 
365239116253401 UE-25 WT #16 123 GS960908312312.010 WT 
365208116274001 USW UZ-14 Estimate GS950508312312.005 WT 
365207116264201 UE-25 WT #18 38 GS960908312312.010 WT 
365200116272901 USW G-1 1 GS991100002330.001 WT 
365147116185301 UE-25 a #3 1 GS991100002330.001 WT 
365140116260301 UE-25 WT #4 131 GS960908312312.010 WT 
365116116233801 UE-25 WT #15 124 GS960908312312.010 WT 
365114116270401 USW G-4 29 GS931008312312.025 
GS970600012847.001 
GS991100002330.001 
WT 
365105116262401 UE-25 a #1 40 GS991100002330.001 WT 
365032116243501 UE-25 WT #14 135 GS960908312312.010 WT

 
 I-8 
USGS Site ID Site Name 
Number of 
Data Points 
Used 
Source Use 
365023116271801 USW WT-2 106 GS960908312312.010 WT 
364947116254300 UE-25 c #1 3 GS991100002330.001 WT 
364947116254501 UE-25 c #3 8 GS960208312312.003 
GS000608312312.004 
GS000708312312.005 
GS000408312312.001 
WT 
364947116254401 UE-25 c #2 10 GS930408312312.015 
GS000608312312.004 
GS000708312312.005 
GS000408312312.001 
GS950108312312.001 
WT 
364945116235001 UE-25 WT #13 118 GS960908312312.010 WT 
364933116285701 USW WT- 7 113 GS960908312312.010 WT 
364916116265601 USW WT- 1 128 GS960908312312.010 WT 
364905116280101 USW G-3 113 GS960908312312.010 WT 
364828116234001 UE-25 J -13 121 GS960908312312.010 WT 
364825116290501 USW WT-10 132 GS960908312312.010 WT 
364822116262601 UE-25 WT #17 117 GS960908312312.010 WT 
365821116343701 USW VH-2 1 GS991100002330.001 WT 
364757116245801 UE-25 WT #3 119 GS960908312312.010 WT 
364732116330701 USW VH-1 147 GS960908312312.010 WT 
364656116261601 UE-25 WT #12 123 GS960908312312.010 WT 
364649116280201 USW WT-11 119 GS960908312312.010 WT 
364554116232400 UE-25 J -12 100 GS960908312312.010 WT 
364528116232201 UE-25 JF #3 234 GS991100002330.001 WT 
364105116302601 Cind-R-Lite Well 62 GS991100002330.001 WT 
363907116235701 Ben Bossingham 1 GS991100002330.001 U 
363836116234001 Fred Cobb 2 GS991100002330.001 U 
363840116235000 Bob Whellock 1 GS991100002330.001 U 
363840116234001 Louise Pereidra 1 GS991100002330.001 U 
363840116233501 Joe Richards 1 GS991100002330.001 U 
363835116234001 NDOT Well 87 GS991100002330.001 WT 
363742116263201 James H. Shaw 3 GS991100002330.001 WT 
363830116241401 Airport Well 90 GS991100002330.001 WT 
363815116175901 TW- 5 99 GS991100002330.001 WT 
363711116263701 Richard Washburn 4 GS991100002330.001 U 
363621116263201 Richard Washburn 1 GS991100002330.001 U 
363549116305001 Nye County Development Co 3 GS991100002330.001 WT 
363523116353701 Fred Wooldridge 3 GS991100002330.001 U 
363525116325601 Fred J. Keefe 6 GS991100002330.001 WT 
363519116322001 Leslie Nickels 4 GS991100002330.001 WT 
363540116240801 L. Mason 22 GS991100002330.001 WT 
363527116292501 Unknown 2 GS991100002330.001 WT 
363521116352501 Davidson Well 63 GS991100002330.001 WT 
363456116335501 Eugene J. Mankinen 4 GS991100002330.001 U 
363454116314201 Donald O. Heath 4 GS991100002330.001 WT 
363503116351501 Elvis Kelley 3 GS991100002330.001 WT 
363503116284001 Manuel Rodela 2 GS991100002330.001 WT 
363436116342301 Charles C. DeFir Jr. 5 GS991100002330.001 WT

 
 I-9 
USGS Site ID Site Name 
Number of 
Data Points 
Used 
Source Use 
363436116333201 William R. Monroe 4 GS991100002330.001 WT 
363434116354001 DeFir Well 19 GS991100002330.001 WT 
363438116324601 Edwin H. Mankinen 4 GS991100002330.001 WT 
363442116363301 Bill Strickland 1 GS991100002330.001 WT 
363440116282401 M. Meese 1 GS991100002330.001 U 
363415116275101 Theo E. Selbach 1 GS991100002330.001 U 
363407116342501 C.L. Caldwell 3 GS991100002330.001 WT 
363407116243501 Leonard Siegel 1 GS991100002330.001 U 
363429116315901 James K. Pierce 3 GS991100002330.001 WT 
363405116321501 James K. Pierce 2 GS991100002330.001 U 
363428116240301 Cooks West Well 3 GS991100002330.001 WT 
363428116234701 Cooks East Well 88 GS991100002330.001 WT 
363417116271801 Nye County Land Company 2 GS991100002330.001 WT 
363411116272901 Amargosa Town Complex 1 GS991100002330.001 WT 
363410116261101 Nye County Development Co 1 GS991100002330.001 WT 
363410116240301 Lewis C. Cook 2 GS991100002330.001 U 
363410116240001 Lewis C. Cook 2 GS991100002330.001 U 
363407116273301 Amargosa Valley Water 1 GS991100002330.001 WT 
363342116335701 Earl N. Selbach 1 GS991100002330.001 U 
363340116332901 Lewis N. Dansby 48 GS991100002330.001 WT 
363342116325101 Edwin H. Mankinen 46 GS991100002330.001 WT 
363350116252101 Willard Johns 2 GS991100002330.001 U 
365157116271202 USW H-1 tube 1 101 GS960908312312.010 C 
365157116271203 USW H-1 tube 2 75 GS960908312312.010 C 
365157116271204 USW H-1 tube 3 108 GS960908312312.010 C 
365157116271205 USW H-1 tube 4 124 GS960908312312.010 WT 
365122116275502 USW H-5 upper 106 GS960908312312.010 WT 
365122116275503 USW H-5 lower 54 GS960908312312.010 C 
365108116262302 UE-25 b #1 lower 67 GS960908312312.010 C 
365108116262303 UE-25 b #1 upper 99 GS960908312312.010 WT 
365049116285502 USW H-6 upper 118 GS960908312312.010 WT 
365049116285505 USW H-6 lower 79 GS960908312312.010 C 
365032116265402 USW H-4 upper 128 GS960908312312.010 WT 
365032116265403 USW H-4 lower 101 GS960908312312.010 C 
364942116280002 USW H-3 upper 128 GS960908312312.010 WT 
364942116280003 USW H-3 lower 59 GS980308312312.004 C 
364938116252102 UE-25 p #1(Lwr Intrvl) 120 GS960908312312.010 C 
not available USW SD-7 1 TM0000000SD7RS.003 U 
not available USW SD-9 1 TM0000000SD9RS.001 WT 
not available USW SD-12 1 TM000000SD12RS.011 WT 
364234116351501 NC-EWDP-1DX, shallow 14 MO0112DQRWLNYE.024 
MO0112DQRWLNYE.017 
WT 
364234116351501 NC-EWDP-1DX, deep 13 MO0112DQRWLNYE.024 
MO0112DQRWLNYE.012 
C 
364233116351501 NC-EWDP-1S, probe 1 26816 MO0112DQRWLNYE.019 
MO0111DQRWLNYE.002 
MO0112DQRWLNYE.023 
WT

 
 I-10 
USGS Site ID Site Name 
Number of 
Data Points 
Used 
Source Use 
364233116351501 NC-EWDP-1S, probe 2 18783 MO0112DQRWLNYE.019 
MO0111DQRWLNYE.002 
MO0112DQRWLNYE.023 
C 
363939116275401 NC-EWDP-2D 2 MO0112DQRWLNYE.024 
MO0112DQRWLNYE.020 
C 
363940116275501 NC-EWDP-2DB 3 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.020 
WT 
364054116321401 NC-EWDP-3D 30 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.016 
C 
364054116321301 NC-EWDP-3S, probe 2 328170 MO0112DQRWLNYE.019 
MO0112DQRWLNYE.015 
MO0112DQRWLNYE.022 
MO0111DQRWLNYE.003 
WT 
364054116321301 NC-EWDP-3S, probe 3 32124 MO0112DQRWLNYE.019 
MO0112DQRWLNYE.015 
MO0111DQRWLNYE.003 
MO0112DQRWLNYE.022 
C 
363925116241501 NC-EWDP-4PA 14 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.005 
WT 
363925116241401 NC-EWDP-4PB 6 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.006 
C 
364012116223401 NC-EWDP-5SB 11 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.008 
WT 
364332116332201 NC-EWDP-7S 3 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.007 
P 
364145116334401 NC-EWDP-9SX, probe 1 29059 MO0112DQRWLNYE.019 
MO0111DQRWLNYE.004 
MO0112DQRWLNYE.021 
MO0112DQRWLNYE.011 
WT 
364145116334401 NC-EWDP-9SX, probe 2 38706 MO0112DQRWLNYE.019 
MO0111DQRWLNYE.004 
MO0112DQRWLNYE.021 
MO0112DQRWLNYE.011 
C 
364145116334401 NC-EWDP-9SX, probe 4 38560 MO0112DQRWLNYE.019 
MO0111DQRWLNYE.004 
MO0112DQRWLNYE.021 
MO0112DQRWLNYE.011 
C 
364137116351001 NC-EWDP-12PA 25 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.010 
C 
364138116351001 NC-EWDP-12PB 25 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.012 
C 
364139116351001 NC-EWDP-12PC 26 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.013 
WT 
364011116294901 NC-EWDP-15P 12 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.009 
WT 
364015116265301 NC-EWDP-19P 9 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.014 
WT 
364014116265301 NC-EWDP-19D 5 MO0112DQRWLNYE.025 
MO0112DQRWLNYE.018 
C 
365301116271301 USW WT-24 11 GS990908312312.005 
GS000608312312.003 
GS000808312312.007 
WT 
363951116252401 NC-Washburn-1X 59 MO0112DQRWLNYE.025 WT 
364706116170601 UE-25 J -11 71 GS960908312312.010 WT 
364237116365401 BGMW-11 51 GS991100002330.001 WT 
363709116264601 Richard Washburn 1 GS991100002330.001 WT

 
 I-11 
USGS Site ID Site Name 
Number of 
Data Points 
Used 
Source Use 
363409116233701 L. Cook 1 GS991100002330.001 U 
363411116264701 Unknown 1 GS991100002330.001 WT 
363428116281201 Amargosa Water 1 GS991100002330.001 WT 
363429116233401 Lewis C. Cook 1 GS991100002330.001 WT 
363511116335101 Unknown 1 GS991100002330.001 WT 
365624116222901 USW UZ-N91 209 GS991100002330.001 WT

 
 I-12 
Table I-3 Reliability of Measurements 
Reliability of Measurements 
Using professional judgement, an assessment of the overall reliability of the average water-level data to represent 1990s water 
levels (Table I-1) was made. The following categories were assigned: 
Best (average water level documented in Graves et al. 1997, DTN: GS960908312312.010) 
Reliable (all others not identified in the other four categories) 
Less Reliable (fewer than 5 water-level measurements) or (latest measurement made prior to 1980) or (only data point available 
within a 5 km radius.) 
Unreliable (fewer than 5 measurements, all made prior to 1980) 
USGS Site ID Site Name Reliability of Measurements 
365629116222602 UE-29 a #2 Reliable 
365520116370301 GEXA Well 4 Reliable 
365340116264601 UE-25 WT #6 Best 
365322116273501 USW G-2 Best 
365239116253401 UE-25 WT #16 Best 
365208116274001 USW UZ-14 Less Reliable (fewer than 5 measurements) 
365207116264201 UE-25 WT #18 Best 
365200116272901 USW G-1 Less Reliable (fewer than 5 measurements) 
365147116185301 UE-25 a #3 Less Reliable (fewer than 5 measurements) 
365140116260301 UE-25 WT #4 Best 
365116116233801 UE-25 WT #15 Best 
365114116270401 USW G-4 Reliable 
365105116262401 UE-25 a #1 Reliable 
365032116243501 UE-25 WT #14 Best 
365023116271801 USW WT-2 Best 
364947116254300 UE-25 c #1 Less Reliable (fewer than 5 measurements) 
364947116254501 UE-25 c #3 Reliable 
364947116254401 UE-25 c #2 Reliable 
364945116235001 UE-25 WT #13 Best 
364933116285701 USW WT- 7 Best 
364916116265601 USW WT- 1 Best 
364905116280101 USW G-3 Best 
364828116234001 UE-25 J -13 Best 
364825116290501 USW WT-10 Best 
364822116262601 UE-25 WT #17 Best 
365821116343701 USW VH-2 Less Reliable (fewer than 5 measurements) 
364757116245801 UE-25 WT #3 Best 
364732116330701 USW VH-1 Best 
364656116261601 UE-25 WT #12 Best 
364649116280201 USW WT-11 Best 
364554116232400 UE-25 J -12 Best 
364528116232201 UE-25 JF #3 Reliable 
364105116302601 Cind-R-Lite Well Reliable 
363907116235701 Ben Bossingham Unreliable (fewer than 5 measurements before 1980) 
363836116234001 Fred Cobb Unreliable (fewer than 5 measurements before 1980) 
363840116235000 Bob Whellock Unreliable (fewer than 5 measurements before 1980) 
363840116234001 Louise Pereidra Unreliable (fewer than 5 measurements before 1980) 
363840116233501 Joe Richards Unreliable (fewer than 5 measurements before 1980) 
363835116234001 NDOT Well Reliable

 
 I-13 
USGS Site ID Site Name Reliability of Measurements 
363742116263201 James H. Shaw Less Reliable (fewer than 5 measurements) 
363830116241401 Airport Well Reliable 
363815116175901 TW- 5 Reliable 
363711116263701 Richard Washburn Unreliable (fewer than 5 measurements before 1980) 
363621116263201 Richard Washburn Unreliable (fewer than 5 measurements before 1980) 
363549116305001 Nye County Development Co Less Reliable (fewer than 5 measurements) 
363523116353701 Fred Wooldridge Unreliable (fewer than 5 measurements before 1980) 
363525116325601 Fred J. Keefe Reliable 
363519116322001 Leslie Nickels Less Reliable (fewer than 5 measurements) 
363540116240801 L. Mason Less Reliable (latest measurement prior to 1980) 
363527116292501 Unknown Less Reliable (fewer than 5 measurements) 
363521116352501 Davidson Well Reliable 
363456116335501 Eugene J. Mankinen Unreliable (fewer than 5 measurements before 1980) 
363454116314201 Donald O. Heath Reliable 
363503116351501 Elvis Kelley Less Reliable (fewer than 5 measurements) 
363503116284001 Manuel Rodela Less Reliable (fewer than 5 measurements) 
363436116342301 Charles C. DeFir Jr. Reliable 
363436116333201 William R. Monroe Reliable 
363434116354001 DeFir Well Reliable 
363438116324601 Edwin H. Mankinen Less Reliable (fewer than 5 measurements) 
363442116363301 Bill Strickland Less Reliable (fewer than 5 measurements) 
363440116282401 M. Meese Unreliable (fewer than 5 measurements before 1980) 
363415116275101 Theo E. Selbach Unreliable (fewer than 5 measurements before 1980) 
363407116342501 C.L. Caldwell Less Reliable (fewer than 5 measurements) 
363407116243501 Leonard Siegel Unreliable (fewer than 5 measurements before 1980) 
363429116315901 James K. Pierce Less Reliable (fewer than 5 measurements) 
363405116321501 James K. Pierce Unreliable (fewer than 5 measurements before 1980) 
363428116240301 Cooks West Well Less Reliable (fewer than 5 measurements) 
363428116234701 Cooks East Well Reliable 
363417116271801 Nye County Land Company Less Reliable (fewer than 5 measurements) 
363411116272901 Amargosa Town Complex Less Reliable (fewer than 5 measurements) 
363410116261101 Nye County Development Co Less Reliable (fewer than 5 measurements) 
363410116240301 Lewis C. Cook Unreliable (fewer than 5 measurements before 1980) 
363410116240001 Lewis C. Cook Unreliable (fewer than 5 measurements before 1980) 
363407116273301 Amargosa Valley Water Less Reliable (fewer than 5 measurements) 
363342116335701 Earl N. Selbach Unreliable (fewer than 5 measurements before 1980) 
363340116332901 Lewis N. Dansby Reliable 
363342116325101 Edwin H. Mankinen Less Reliable (latest measurement prior to 1980) 
363350116252101 Willard Johns Unreliable (fewer than 5 measurements before 1980) 
365157116271202 USW H-1 tube 1 Best 
365157116271203 USW H-1 tube 2 Best 
365157116271204 USW H-1 tube 3 Best 
365157116271205 USW H-1 tube 4 Best 
365122116275502 USW H-5 upper Best 
365122116275503 USW H-5 lower Best 
365108116262302 UE-25 b #1 lower Best 
365108116262303 UE-25 b #1 upper Best 
365049116285502 USW H-6 upper Best 
365049116285505 USW H-6 lower Best

 
 I-14 
USGS Site ID Site Name Reliability of Measurements 
365032116265402 USW H-4 upper Best 
365032116265403 USW H-4 lower Best 
364942116280002 USW H-3 upper Best 
364942116280003 USW H-3 lower Best 
364938116252102 UE-25 p #1(Lwr Intrvl) Best 
not available yet USW SD-7 Less Reliable (fewer than 5 measurements) 
not available yet USW SD-9 Less Reliable (fewer than 5 measurements) 
not available yet USW SD-12 Less Reliable (fewer than 5 measurements) 
364234116351501 NC-EWDP-1DX, shallow Reliable 
364234116351501 NC-EWDP-1DX, deep Reliable 
364233116351501 NC-EWDP-1S, probe 1 Reliable 
364233116351501 NC-EWDP-1S, probe 2 Reliable 
363939116275401 NC-EWDP-2D Less Reliable (fewer than 5 measurements) 
363940116275501 NC-EWDP-2DB Less Reliable (fewer than 5 measurements) 
364054116321401 NC-EWDP-3D Reliable 
364054116321301 NC-EWDP-3S, probe 2 Reliable 
364054116321301 NC-EWDP-3S, probe 3 Reliable 
363925116241501 NC-EWDP-4PA Reliable 
363925116241401 NC-EWDP-4PB Reliable 
364012116223401 NC-EWDP-5SB Reliable 
364332116332201 NC-EWDP-7S Less Reliable (fewer than 5 measurements) 
364145116334401 NC-EWDP-9SX, probe 1 Reliable 
364145116334401 NC-EWDP-9SX, probe 2 Reliable 
364145116334401 NC-EWDP-9SX, probe 4 Reliable 
364137116351001 NC-EWDP-12PA Reliable 
364138116351001 NC-EWDP-12PB Reliable 
364139116351001 NC-EWDP-12PC Reliable 
364011116294901 NC-EWDP-15P Reliable 
364015116265301 NC-EWDP-19P Reliable 
364014116265301 NC-EWDP-19D Reliable 
365301116271301 USW WT-24 Reliable 
363951116252401 NC-Washburn-1X Reliable 
364706116170601 UE-25 J -11 Best 
364237116365401 BGMW-11 Reliable 
363709116264601 Richard Washburn Less Reliable (fewer than 5 measurements) 
363409116233701 L. Cook Unreliable (fewer than 5 measurements before 1980) 
363411116264701 Unknown Less Reliable (fewer than 5 measurements) 
363428116281201 Amargosa Water Less Reliable (fewer than 5 measurements) 
363429116233401 Lewis C. Cook Less Reliable (fewer than 5 measurements) 
363511116335101 Unknown Less Reliable (fewer than 5 measurements) 
365624116222901 USW UZ-N91 Reliable

 
 I-15 
Table I-4 Earliest Year of Measurement, Latest Year of Measurement, Minimum Water-level Altitude, and Maximum 
Water-level Altitude (DTN: GS010908312332.002) 
Earliest Year of Measurement/Latest Year of Measurement 
The earliest and latest year of reported measurement used in the calculation of the mean was determined and recorded. The data 
tabulated by Graves et al. (1997) were not checked for earlier or later measurements. The data reported in Graves et al. (1997) 
were collected for the water-level monitoring studies being conducted as part of Yucca Mountain site characterization activities 
and, as such, were collected after 1986 under an approved quality assurance program. 
Minimum Water-level Altitude/Maximum Water-level Altitude (meters) 
The smallest and largest water-level altitudes for the data used to calculate mean water-level altitude were compiled and 
tabulated. The altitude was converted from feet to meters by the following formula, where necessary: 
Altitude (ft) x 0.3048 (m/ft) = Altitude (m) 
The altitude was rounded to the nearest tenth of a meter. 
USGS Site ID Site Name Earliest Year of 
Measurement 
Latest Year of 
Measurement 
Minimum 
Water-level 
Altitude (m) 
Maximum 
Water-level 
Altitude (m) 
365629116222602 UE-29 a #2 1985 1996 1186.2 1191.3 
365520116370301 GEXA Well 4 1989 1996 995.3 1010.1 
365340116264601 UE-25 WT #6 1985 1995 1033.3 1036.1 
365322116273501 USW G-2 1992 1995 1019.6 1020.6 
365239116253401 UE-25 WT #16 1985 1995 737.8 738.6 
365208116274001 USW UZ-14 N/A N/A N/A N/A 
365207116264201 UE-25 WT #18 1991 1995 730.5 730.9 
365200116272901 USW G-1 1982 1982 754.2 754.2 
365147116185301 UE-25 a #3 1979 1979 748.3 748.3 
365140116260301 UE-25 WT #4 1985 1995 730.3 731.2 
365116116233801 UE-25 WT #15 1985 1995 729.0 729.4 
365114116270401 USW G-4 1983 1990 730.0 730.9 
365105116262401 UE-25 a #1 1982 1985 730.7 731.2 
365032116243501 UE-25 WT #14 1985 1995 729.3 730.0 
365023116271801 USW WT-2 1985 1995 730.1 730.8 
364947116254300 UE-25 c #1 1983 1984 730.1 730.3 
364947116254501 UE-25 c #3 1989 1995 730.1 730.3 
364947116254401 UE-25 c #2 1989 1995 729.9 730.6 
364945116235001 UE-25 WT #13 1985 1995 728.5 729.4 
364933116285701 USW WT- 7 1985 1995 775.5 776.0 
364916116265601 USW WT- 1 1985 1995 730.0 730.5 
364905116280101 USW G-3 1985 1995 730.0 730.8 
364828116234001 UE-25 J -13 1986 1995 728.3 728.7 
364825116290501 USW WT-10 1985 1995 775.6 776.2 
364822116262601 UE-25 WT #17 1985 1995 729.5 729.8 
365821116343701 USW VH-2 1983 1983 810.4 810.4 
364757116245801 UE-25 WT #3 1985 1995 729.4 729.9 
364732116330701 USW VH-1 1985 1995 779.3 779.6 
364656116261601 UE-25 WT #12 1985 1995 729.1 729.6 
364649116280201 USW WT-11 1985 1995 730.2 730.8 
364554116232400 UE-25 J -12 1989 1995 727.8 728.2 
364528116232201 UE-25 JF #3 1992 1998 727.3 728.1

 
 I-16 
USGS Site ID Site Name Earliest Year of 
Measurement 
Latest Year of 
Measurement 
Minimum 
Water-level 
Altitude (m) 
Maximum 
Water-level 
Altitude (m) 
364105116302601 Cind-R-Lite Well 1992 1998 727.1 729.9 
363907116235701 Ben Bossingham 1961 1961 718.4 718.4 
363836116234001 Fred Cobb 1964 1990 700.1 705.4 
363840116235000 Bob Whellock 1955 1955 704.1 704.1 
363840116234001 Louise Pereidra 1952 1952 705.6 705.6 
363840116233501 Joe Richards 1955 1955 701.6 701.6 
363835116234001 NDOT Well 1991 1998 704.9 705.6 
363742116263201 James H. Shaw 1953 1987 705.4 708.1 
363830116241401 Airport Well 1987 1998 705.2 705.5 
363815116175901 TW- 5 1962 1998 724.8 729.2 
363711116263701 Richard Washburn 1958 1962 706.1 709.3 
363621116263201 Richard Washburn 1958 1958 704.4 704.4 
363549116305001 Nye County Development 
Co 
1963 1987 691.3 695.9 
363523116353701 Fred Wooldridge 1960 1984 688.4 694.0 
363525116325601 Fred J. Keefe 1960 1987 691.4 696.3 
363519116322001 Leslie Nickels 1962 1987 693.5 696.1 
363540116240801 L. Mason 1963 1973 721.5 726.0 
363527116292501 Unknown 1962 1987 696.9 698.7 
363521116352501 Davidson Well 1963 1998 689.7 692.0 
363456116335501 Eugene J. Mankinen 1961 1962 707.1 707.7 
363454116314201 Donald O. Heath 1962 1987 693.2 696.2 
363503116351501 Elvis Kelley 1984 1987 690.5 691.3 
363503116284001 Manuel Rodela 1965 1987 692.2 694.9 
363436116342301 Charles C. DeFir Jr. 1959 1987 705.3 708.8 
363436116333201 William R. Monroe 1962 1987 691.5 696.0 
363434116354001 DeFir Well 1987 1993 689.1 690.4 
363438116324601 Edwin H. Mankinen 1961 1987 692.4 698.0 
363442116363301 Bill Strickland 1982 1982 689.2 689.2 
363440116282401 M. Meese 1962 1962 686.4 686.4 
363415116275101 Theo E. Selbach 1958 1958 696.2 696.2 
363407116342501 C.L. Caldwell 1958 1984 690.1 692.8 
363407116243501 Leonard Siegel 1962 1962 709.0 709.0 
363429116315901 James K. Pierce 1965 1987 689.5 692.1 
363405116321501 James K. Pierce 1960 1962 704.7 706.6 
363428116240301 Cooks West Well 1987 1991 719.6 720.4 
363428116234701 Cooks East Well 1987 1998 717.7 720.3 
363417116271801 Nye County Land 
Company 
1962 1984 688.3 691.9 
363411116272901 Amargosa Town Complex 1980 1980 688.8 688.8 
363410116261101 Nye County Development 
Co 
1987 1987 691.2 691.2 
363410116240301 Lewis C. Cook 1966 1987 714.0 720.9 
363410116240001 Lewis C. Cook 1962 1987 705.9 723.6 
363407116273301 Amargosa Valley Water 1988 1988 701.3 701.3 
363342116335701 Earl N. Selbach 1958 1958 696.5 696.5 
363340116332901 Lewis N. Dansby 1954 1987 692.4 696.2 
363342116325101 Edwin H. Mankinen 1955 1974 692.7 695.1 
363350116252101 Willard Johns 1959 1962 698.5 700.4

 
 I-17 
USGS Site ID Site Name Earliest Year of 
Measurement 
Latest Year of 
Measurement 
Minimum 
Water-level 
Altitude (m) 
Maximum 
Water-level 
Altitude (m) 
365157116271202 USW H-1 tube 1 1985 1995 785.0 786.1 
365157116271203 USW H-1 tube 2 1985 1995 735.7 736.3 
365157116271204 USW H-1 tube 3 1985 1995 730.4 730.8 
365157116271205 USW H-1 tube 4 1985 1995 730.5 731.0 
365122116275502 USW H-5 upper 1985 1995 775.0 775.7 
365122116275503 USW H-5 lower 1985 1995 775.0 775.9 
365108116262302 UE-25 b #1 lower 1985 1995 728.5 730.3 
365108116262303 UE-25 b #1 upper 1985 1995 730.5 730.8 
365049116285502 USW H-6 upper 1985 1995 775.8 776.2 
365049116285505 USW H-6 lower 1988 1995 775.7 776.1 
365032116265402 USW H-4 upper 1985 1995 730.2 730.5 
365032116265403 USW H-4 lower 1985 1995 730.2 730.8 
364942116280002 USW H-3 upper 1985 1995 731.1 731.9 
364942116280003 USW H-3 lower 1991 1996 747.4 760.3 
364938116252102 UE-25 p #1(Lwr Intrvl) 1985 1995 751.9 752.7 
not available yet USW SD-7 1995 1995 727.6 727.6 
not available yet USW SD-9 1994 1994 731.1 731.1 
not available yet USW SD-12 1995 1995 730.0 730.0 
364234116351501 NC-EWDP-1DX, shallow 1999 2000 786.7 786.8 
364234116351501 NC-EWDP-1DX, deep 1999 2000 748.7 748.9 
364233116351501 NC-EWDP-1S, probe 1 1999 2000 787.1 787.2 
364233116351501 NC-EWDP-1S, probe 2 1999 2000 786.7 786.9 
363939116275401 NC-EWDP-2D 1999 1999 706.1 706.2 
363940116275501 NC-EWDP-2DB 2000 2000 712.3 713.7 
364054116321401 NC-EWDP-3D 1999 2000 717.4 719.3 
364054116321301 NC-EWDP-3S, probe 2 1999 2000 719.7 720.0 
364054116321301 NC-EWDP-3S, probe 3 1999 2000 719.2 719.5 
363925116241501 NC-EWDP-4PA 2000 2000 717.1 718.7 
363925116241401 NC-EWDP-4PB 2000 2000 723.4 723.8 
364012116223401 NC-EWDP-5SB 2000 2000 723.4 723.6 
364332116332201 NC-EWDP-7S 2000 2000 829.9 830.2 
364145116334401 NC-EWDP-9SX, probe 1 1999 2000 766.6 766.7 
364145116334401 NC-EWDP-9SX, probe 2 1999 2000 767.2 767.4 
364145116334401 NC-EWDP-9SX, probe 4 1999 2000 766.7 766.8 
364137116351001 NC-EWDP-12PA 2000 2000 722.8 723.0 
364138116351001 NC-EWDP-12PB 2000 2000 722.9 732.2 
364139116351001 NC-EWDP-12PC 2000 2000 720.3 720.8 
364011116294901 NC-EWDP-15P 2000 2000 722.4 722.6 
364015116265301 NC-EWDP-19P 2000 2000 707.4 707.7 
364014116265301 NC-EWDP-19D 2000 2000 712.6 712.9 
365301116271301 USW WT-24 1999 1999 839.7 840.7 
363951116252401 NC-Washburn-1X 1999 2000 714.4 714.7 
364706116170601 UE-25 J -11 1989 1995 732.1 732.4 
364237116365401 BGMW-11 1989 1999 715.5 716.2 
363709116264601 Richard Washburn 1987 1987 704.0 704.0 
363409116233701 L. Cook 1962 1962 713.2 713.2 
363411116264701 Unknown 1987 1987 689.5 689.5 
363428116281201 Amargosa Water 1987 1987 690.4 690.4

 
 I-18 
USGS Site ID Site Name Earliest Year of 
Measurement 
Latest Year of 
Measurement 
Minimum 
Water-level 
Altitude (m) 
Maximum 
Water-level 
Altitude (m) 
363429116233401 Lewis C. Cook 1987 1987 715.7 715.7 
363511116335101 Unknown 1987 1987 690.8 690.8 
365624116222901 USW UZ-N91 1986 1996 1185.6 1191.3

 
 I-19 
Table I-5 Top of Interval, Bottom of Interval, and Midpoint of Interval 
Top of Interval/Bottom of Interval (meters) 
Where available, the altitude of the top and bottom of screened or packed-off intervals were used. If the altitude of the screened 
or packed-off interval was not available, the borehole was treated as an open borehole. If the altitude of the bottom of a borehole 
interval was not available, the altitude of the base of the borehole was used for the bottom of the interval. Likewise, if the 
altitude of the top of a borehole interval was not available, the maximum water level was used for the altitude of the top of the 
interval. The altitudes were converted from feet to meters by the following formula: 
Altitude (ft) x 0.3048 (m/ft) = Altitude (m) 
The altitude was rounded to the nearest tenth of a meter. 
Midpoint of Interval (meters) 
Most of the water levels represent a composite water-level altitude for a borehole. Composite water-level altitudes refer to water 
levels derived from an open interval that may encompass one or more hydrogeologic units , in which any portion of the open 
interval may contribute to the water level. Because the altitude at which the hydraulic head measurement applies is uncertain, the 
midpoint of either the water column for open (uncased) boreholes or the midpoint of a screened or packed-off interval within the 
borehole is identified. The altitude of the midpoint of the interval was calculated by the following formula: 
Midpoint = (Top+Bottom)/2 
The altitude was rounded to the nearest tenth of a meter. 
Sources 
Sources are tabulated in Table I-2 
USGS Site ID Site Name Top of Interval 
(m) 
Bottom of Interval 
(m) 
Midpoint of Interval 
(m) 
365629116222602 UE-29 a #2 1187.7 793.9 990.8 
365520116370301 GEXA Well 4 1008.0 710.5 859.2 
365340116264601 UE-25 WT #6 1034.6 931.8 983.2 
365322116273501 USW G-2 1020.2 748.0 884.1 
365239116253401 UE-25 WT #16 738.3 689.9 714.1 
365208116274001 USW UZ-14 915.9 670.9 793.4 
365207116264201 UE-25 WT #18 730.8 713.4 722.1 
365200116272901 USW G-1 754.2 -502.9 125.7 
365147116185301 UE-25 a #3 748.3 614.5 681.4 
365140116260301 UE-25 WT #4 730.8 687.3 709.0 
365116116233801 UE-25 WT #15 729.2 668.2 698.7 
365114116270401 USW G-4 730.1 354.2 542.2 
365105116262401 UE-25 a #1 731.0 436.9 584.0 
365032116243501 UE-25 WT #14 729.7 677.4 703.6 
365023116271801 USW WT-2 730.7 673.4 702.0 
364947116254300 UE-25 c #1 730.3 216.2 473.2 
364947116254501 UE-25 c #3 730.3 218.3 474.3 
364947116254401 UE-25 c #2 730.2 376.3 553.2 
364945116235001 UE-25 WT #13 729.1 678.5 703.8 
364933116285701 USW WT- 7 775.8 705.9 740.9 
364916116265601 USW WT- 1 730.4 686.4 708.4 
364905116280101 USW G-3 688.6 -52.4 318.1 
364828116234001 UE-25 J -13 707.7 1.8 354.8 
364825116290501 USW WT-10 776.0 692.4 734.2 
364822116262601 UE-25 WT #17 729.7 681.0 705.4

 
 I-20 
USGS Site ID Site Name Top of Interval 
(m) 
Bottom of Interval 
(m) 
Midpoint of Interval 
(m) 
365821116343701 USW VH-2 810.5 -244.8 282.8 
364757116245801 UE-25 WT #3 729.6 682.0 705.8 
364732116330701 USW VH-1 779.4 201.5 490.5 
364656116261601 UE-25 WT #12 729.5 675.7 702.6 
364649116280201 USW WT-11 730.7 653.1 691.9 
364554116232400 UE-25 J -12 712.6 606.6 659.6 
364528116232201 UE-25 JF #3 727.8 597.5 662.7 
364105116302601 Cind-R-Lite Well 729.8 690.6 710.2 
363907116235701 Ben Bossingham 718.4 676.4 697.4 
363836116234001 Fred Cobb 702.8 648.3 675.6 
363840116235000 Bob Whellock 704.1 659.9 682.0 
363840116234001 Louise Pereidra 705.6 690.4 698.0 
363840116233501 Joe Richards 701.7 656.9 679.3 
363835116234001 NDOT Well 705.3 658.9 682.1 
363742116263201 James H. Shaw 706.7 621.8 664.3 
363830116241401 Airport Well 705.5 567.5 636.5 
363815116175901 TW- 5 725.1 652.3 688.7 
363711116263701 Richard Washburn 707.7 632.2 669.9 
363621116263201 Richard Washburn 704.4 646.2 675.3 
363549116305001 Nye County Development Co 694.4 582.8 638.6 
363523116353701 Fred Wooldridge 691.9 655.6 673.8 
363525116325601 Fred J. Keefe 694.3 659.0 676.7 
363519116322001 Leslie Nickels 694.4 615.1 654.7 
363540116240801 L. Mason 722.1 676.4 699.2 
363527116292501 Unknown 697.8 637.4 667.6 
363521116352501 Davidson Well 690.2 653.9 672.0 
363456116335501 Eugene J. Mankinen 707.4 649.9 678.6 
363454116314201 Donald O. Heath 698.1 605.0 651.6 
363503116351501 Elvis Kelley 691.0 679.1 685.1 
363503116284001 Manuel Rodela 693.6 679.7 686.7 
363436116342301 Charles C. DeFir Jr. 706.9 664.5 685.7 
363436116333201 William R. Monroe 699.0 640.1 669.5 
363434116354001 DeFir Well 691.3 650.9 671.1 
363438116324601 Edwin H. Mankinen 695.2 630.3 662.8 
363442116363301 Bill Strickland 689.2 664.8 677.0 
363440116282401 M. Meese 686.4 642.8 664.6 
363415116275101 Theo E. Selbach 696.2 650.5 673.3 
363407116342501 C.L. Caldwell 691.4 617.5 654.5 
363407116243501 Leonard Siegel 709.0 625.5 667.2 
363429116315901 James K. Pierce 690.4 637.7 664.0 
363405116321501 James K. Pierce 705.7 648.6 677.1 
363428116240301 Cooks West Well 717.2 663.1 690.2 
363428116234701 Cooks East Well 718.8 668.1 693.4 
363417116271801 Nye County Land Company 690.1 740.7 715.4 
363411116272901 Amargosa Town Complex 688.9 647.7 668.3 
363410116261101 Nye County Development Co 691.2 539.5 615.4 
363410116240301 Lewis C. Cook 717.4 687.7 702.5 
363410116240001 Lewis C. Cook 714.8 662.7 688.7 
363407116273301 Amargosa Valley Water 701.4 646.5 673.9

 
 I-21 
USGS Site ID Site Name Top of Interval 
(m) 
Bottom of Interval 
(m) 
Midpoint of Interval 
(m) 
363342116335701 Earl N. Selbach 696.5 647.7 672.1 
363340116332901 Lewis N. Dansby 694.2 635.2 664.7 
363342116325101 Edwin H. Mankinen 694.0 678.5 686.2 
363350116252101 Willard Johns 699.5 658.4 678.9 
365157116271202 USW H-1 tube 1 -480.0 -511.0 -495.5 
365157116271203 USW H-1 tube 2 206.0 180.0 193.0 
365157116271204 USW H-1 tube 3 587.0 538.0 562.5 
365157116271205 USW H-1 tube 4 731.0 630.0 680.5 
365122116275502 USW H-5 upper 775.5 632.9 704.2 
365122116275503 USW H-5 lower 632.9 259.9 446.4 
365108116262302 UE-25 b #1 lower 1.7 -19.3 -8.8 
365108116262303 UE-25 b #1 upper 730.7 1.7 366.2 
365049116285502 USW H-6 upper 776.0 549.8 662.9 
365049116285505 USW H-6 lower 549.8 81.8 315.8 
365032116265402 USW H-4 upper 730.4 60.5 395.5 
365032116265403 USW H-4 lower 60.5 29.5 45.0 
364942116280002 USW H-3 upper 731.5 422.2 576.9 
364942116280003 USW H-3 lower 422.2 264.2 343.2 
364938116252102 UE-25 p #1(Lwr Intrvl) -129.8 -690.8 -410.3 
not available USW SD-7 727.6 547.7 637.7 
not available USW SD-9 731.1 625.6 678.3 
not available USW SD-12 730.0 663.4 696.7 
364234116351501 NC-EWDP-1DX, shallow 786.8 384.6 585.7 
364234116351501 NC-EWDP-1DX, deep 145.6 120.6 133.1 
364233116351501 NC-EWDP-1S, probe 1 754.8 748.8 751.8 
364233116351501 NC-EWDP-1S, probe 2 739.8 721.8 730.8 
363939116275401 NC-EWDP-2D 706.1 308.1 294.3 
363940116275501 NC-EWDP-2DB -18.7 -136 -77 
364054116321401 NC-EWDP-3D 718.3 37.4 377.9 
364054116321301 NC-EWDP-3S, probe 2 695.8 669.8 682.8 
364054116321301 NC-EWDP-3S, probe 3 653.8 630.8 642.3 
363925116241501 NC-EWDP-4PA 699.0 675.0 687.0 
363925116241401 NC-EWDP-4PB 598.0 567.0 582.5 
364012116223401 NC-EWDP-5SB 724.3 691.3 707.8 
364332116332201 NC-EWDP-7S 828.4 824.7 826.6 
364145116334401 NC-EWDP-9SX, probe 1 770.3 760.3 765.3 
364145116334401 NC-EWDP-9SX, probe 2 754.3 748.3 751.3 
364145116334401 NC-EWDP-9SX, probe 4 696.3 693.3 694.8 
364137116351001 NC-EWDP-12PA 675.7 657.7 666.7 
364138116351001 NC-EWDP-12PB 675.7 657.7 666.7 
364139116351001 NC-EWDP-12PC 722.7 704.7 713.7 
364011116294901 NC-EWDP-15P 725.9 707.9 716.9 
364015116265301 NC-EWDP-19P 710.2 679.2 694.7 
364014116265301 NC-EWDP-19D 713.2 386.2 549.7 
365301116271301 USW WT-24 840.1 629.8 734.7 
363951116252401 NC-Washburn-1X 696.1 677.8 687.0 
364706116170601 UE-25 J -11 721.2 653.3 687.2 
364237116365401 BGMW-11 715.9 631.0 673.4 
363709116264601 Richard Washburn 704.1 775.7 739.9

 
 I-22 
USGS Site ID Site Name Top of Interval 
(m) 
Bottom of Interval 
(m) 
Midpoint of Interval 
(m) 
363409116233701 L. Cook 713.3 695.0 704.1 
363411116264701 Unknown 689.5 694.1 691.8 
363428116281201 Amargosa Water 690.4 738.2 714.3 
363429116233401 Lewis C. Cook 715.7 755.3 735.5 
363511116335101 Unknown 690.8 729.4 710.1 
365624116222901 USW UZ-N91 1186.8 1174.4 1180.6

 
 I-23 
Table I-6 Interval Description and Accuracy of Location 
Interval Description 
Where available, the interval type and description were compiled from the NWIS data files (DTN: GS991100002330.001), and 
from various Nye County datasets. 
Accuracy of Location/Accuracy of Land-surface Altitude (meters) 
Location and land-surface altitude accuracy, where available, were compiled from the NWIS data files (DTN: 
GS991100002330.001). 
Sources 
Sources are tabulated in Table I-2 
USGS Site ID Site Name Interval Description Accuracy of 
Location 
365629116222602 UE-29 a #2 Open Hole, No Screen +/- 1 second 
365520116370301 GEXA Well 4 Perforated, Porous, or Slotted Casing +/- 1 second 
365340116264601 UE-25 WT #6 Wire-Wound Screen +/- 10 seconds 
365322116273501 USW G-2 Open Hole, No Screen +/- 1 second 
365239116253401 UE-25 WT #16 Wire-Wound Screen +/- 1 second 
365208116274001 USW UZ-14 Fractured Rock Openings unknown 
365207116264201 UE-25 WT #18 Wire-Wound Screen +/- 1 second 
365200116272901 USW G-1 Open Hole, No Screen +/- 1 second 
365147116185301 UE-25 a #3 Open Hole, No Screen +/- 1 second 
365140116260301 UE-25 WT #4 Wire-Wound Screen +/- 1 second 
365116116233801 UE-25 WT #15 Open Hole, No Screen +/- 1 second 
365114116270401 USW G-4 Open Hole, No Screen +/- 1 second 
365105116262401 UE-25 a #1 Unknown +/- 1 second 
365032116243501 UE-25 WT #14 Wire-Wound Screen +/- 1 second 
365023116271801 USW WT-2 Wire-Wound Screen +/- 1 second 
364947116254300 UE-25 c #1 Composite interval - entire saturated 
section 
+/- 1 second 
364947116254501 UE-25 c #3 Composite interval - entire saturated 
section 
+/- 1 second 
364947116254401 UE-25 c #2 Upper interval - above inflatable packer +/- 1 second 
364945116235001 UE-25 WT #13 Open Hole, No Screen +/- 1 second 
364933116285701 USW WT- 7 Wire-Wound Screen +/- 1 second 
364916116265601 USW WT- 1 Wire-Wound Screen +/- 1 second 
364905116280101 USW G-3 Open Hole, No Screen +/- 1 second 
364828116234001 UE-25 J -13 Open Hole, No Screen +/- 1 second 
364825116290501 USW WT-10 Wire-Wound Screen +/- 1 second 
364822116262601 UE-25 WT #17 Wire-Wound Screen +/- 1 second 
365821116343701 USW VH-2 Fractured Rock Openings 
364757116245801 UE-25 WT #3 Wire-Wound Screen +/- 1 second 
364732116330701 USW VH-1 Open Hole, No Screen +/- 1 second 
364656116261601 UE-25 WT #12 Wire-Wound Screen +/- 1 second 
364649116280201 USW WT-11 Wire-Wound Screen +/- 1 second 
364554116232400 UE-25 J -12 Perforated, Porous, or Slotted Casing 
364528116232201 UE-25 JF #3 Perforated, Porous, or Slotted Casing +/- 1 second 
364105116302601 Cind-R-Lite Well Perforated, Porous, or Slotted Casing +/- 1 second 
363907116235701 Ben Bossingham Perforated, Porous, or Slotted Casing +/- 1 second 
363836116234001 Fred Cobb Perforated, Porous, or Slotted Casing +/- 1 second 
363840116235000 Bob Whellock Perforated, Porous, or Slotted Casing +/- 5 seconds

 
 I-24 
USGS Site ID Site Name Interval Description Accuracy of 
Location 
363840116234001 Louise Pereidra Perforated, Porous, or Slotted Casing +/- 1 minute 
363840116233501 Joe Richards Perforated, Porous, or Slotted Casing +/- 1 second 
363835116234001 NDOT Well Perforated, Porous, or Slotted Casing +/- 1 second 
363742116263201 James H. Shaw Perforated, Porous, or Slotted Casing +/- 5 seconds 
363830116241401 Airport Well Perforated, Porous, or Slotted Casing +/- 1 second 
363815116175901 TW- 5 Open Hole, No Screen +/- 1 second 
363711116263701 Richard Washburn Perforated, Porous, or Slotted Casing +/- 5 seconds 
363621116263201 Richard Washburn Perforated, Porous, or Slotted Casing +/- 5 seconds 
363549116305001 Nye County Development Co Perforated, Porous, or Slotted Casing +/- 1 second 
363523116353701 Fred Wooldridge Perforated, Porous, or Slotted Casing +/- 10 seconds 
363525116325601 Fred J. Keefe Perforated, Porous, or Slotted Casing +/- 5 seconds 
363519116322001 Leslie Nickels Perforated, Porous, or Slotted Casing +/- 5 seconds 
363540116240801 L. Mason Perforated, Porous, or Slotted Casing +/- 10 seconds 
363527116292501 Unknown Unknown +/- 5 seconds 
363521116352501 Davidson Well Perforated, Porous, or Slotted Casing +/- 5 seconds 
363456116335501 Eugene J. Mankinen Perforated, Porous, or Slotted Casing +/- 1 minute 
363454116314201 Donald O. Heath Perforated, Porous, or Slotted Casing +/- 5 seconds 
363503116351501 Elvis Kelley Perforated, Porous, or Slotted Casing +/- 5 seconds 
363503116284001 Manuel Rodela Perforated, Porous, or Slotted Casing +/- 5 seconds 
363436116342301 Charles C. DeFir Jr. Perforated, Porous, or Slotted Casing +/- 5 seconds 
363436116333201 William R. Monroe Perforated, Porous, or Slotted Casing +/- 5 seconds 
363434116354001 DeFir Well Perforated, Porous, or Slotted Casing +/- 5 seconds 
363438116324601 Edwin H. Mankinen Perforated, Porous, or Slotted Casing +/- 5 seconds 
363442116363301 Bill Strickland Perforated, Porous, or Slotted Casing +/- 1 second 
363440116282401 M. Meese Unknown +/- 1 minute 
363415116275101 Theo E. Selbach Unknown +/- 10 seconds 
363407116342501 C.L. Caldwell Perforated, Porous, or Slotted Casing +/- 10 seconds 
363407116243501 Leonard Siegel Unknown +/- 1 minute 
363429116315901 James K. Pierce Perforated, Porous, or Slotted Casing +/- 1 second 
363405116321501 James K. Pierce Perforated, Porous, or Slotted Casing +/- 10 seconds 
363428116240301 Cooks West Well Perforated, Porous, or Slotted Casing +/- 5 seconds 
363428116234701 Cooks East Well Perforated, Porous, or Slotted Casing +/- 5 seconds 
363417116271801 Nye County Land Company Unknown +/- 1 minute 
363411116272901 Amargosa Town Complex Perforated, Porous, or Slotted Casing +/- 1 second 
363410116261101 Nye County Development Co Perforated, Porous, or Slotted Casing +/- 5 seconds 
363410116240301 Lewis C. Cook Perforated, Porous, or Slotted Casing +/- 5 seconds 
363410116240001 Lewis C. Cook Perforated, Porous, or Slotted Casing +/- 5 seconds 
363407116273301 Amargosa Valley Water Perforated, Porous, or Slotted Casing +/- 1 second 
363342116335701 Earl N. Selbach Unknown +/- 10 seconds 
363340116332901 Lewis N. Dansby Perforated, Porous, or Slotted Casing +/- 5 seconds 
363342116325101 Edwin H. Mankinen Unknown +/- 10 seconds 
363350116252101 Willard Johns Perforated, Porous, or Slotted Casing +/- 10 seconds 
365157116271202 USW H-1 tube 1 Tube 1 - deepest interval in piezometer +/- 1 second 
365157116271203 USW H-1 tube 2 Tube 2 - second deepest interval in 
piezometer 
+/- 1 second 
365157116271204 USW H-1 tube 3 Tube 3 - second shallowest interval in 
piezometer 
+/- 1 second 
365157116271205 USW H-1 tube 4 Tube 4 - shallowest interval in 
piezometer 
+/- 1 second

 
 I-25 
USGS Site ID Site Name Interval Description Accuracy of 
Location 
365122116275502 USW H-5 upper Upper interval - above inflatable packer +/- 1 second 
365122116275503 USW H-5 lower Lower interval - below inflatable packer +/- 1 second 
365108116262302 UE-25 b #1 lower Lower interval - below inflatable packer +/- 1 second 
365108116262303 UE-25 b #1 upper Upper interval - above inflatable packer +/- 1 second 
365049116285502 USW H-6 upper Upper interval - above inflatable packer +/- 1 second 
365049116285505 USW H-6 lower Lower interval - below inflatable packer +/- 1 second 
365032116265402 USW H-4 upper Upper interval - above inflatable packer +/- 1 second 
365032116265403 USW H-4 lower Lower interval - below inflatable packer +/- 1 second 
364942116280002 USW H-3 upper Upper interval - above inflatable packer +/- 1 second 
364942116280003 USW H-3 lower Lower interval - below inflatable packer +/- 1 second 
364938116252102 UE-25 p #1(Lwr Intrvl) Paleozoics units monitored +/- 1 second 
not available yet USW SD-7 Fractured Rock Openings unknown 
not available yet USW SD-9 Fractured Rock Openings unknown 
not available yet USW SD-12 Fractured Rock Openings unknown 
364234116351501 NC-EWDP-1DX, shallow Screen, above inflatable packer unknown 
364234116351501 NC-EWDP-1DX, deep Screen, below inflatable packer unknown 
364233116351501 NC-EWDP-1S, probe 1 Screen, between inflatable packers unknown 
364233116351501 NC-EWDP-1S, probe 2 Screen, between inflatable packers unknown 
363939116275401 NC-EWDP-2D Open Hole, No Screen unknown 
363940116275501 NC-EWDP-2DB Open Hole, No Screen unknown 
364054116321401 NC-EWDP-3D Open Hole, No Screen unknown 
364054116321301 NC-EWDP-3S, probe 2 Screen, between inflatable packers unknown 
364054116321301 NC-EWDP-3S, probe 3 Screen, between inflatable packers unknown 
363925116241501 NC-EWDP-4PA Screen, above inflatable packer unknown 
363925116241401 NC-EWDP-4PB Screen, below inflatable packer unknown 
364012116223401 NC-EWDP-5SB Screen unknown 
364332116332201 NC-EWDP-7S Screen unknown 
364145116334401 NC-EWDP-9SX, probe 1 Screen, between inflatable packers unknown 
364145116334401 NC-EWDP-9SX, probe 2 Screen, between inflatable packers unknown 
364145116334401 NC-EWDP-9SX, probe 4 Screen, below inflatable packer unknown 
364137116351001 NC-EWDP-12PA Screen, between inflatable packers unknown 
364138116351001 NC-EWDP-12PB Screen, between inflatable packers unknown 
364139116351001 NC-EWDP-12PC Screen, between inflatable packers unknown 
364011116294901 NC-EWDP-15P Screen unknown 
364015116265301 NC-EWDP-19P Screen unknown 
364014116265301 NC-EWDP-19D Screen, various intervals unknown 
365301116271301 USW WT-24 Open Hole, No Screen unknown 
363951116252401 NC-Washburn-1X Screen unknown 
364706116170601 UE-25 J -11 Open Hole, No Screen +/- 1 second 
364237116365401 BGMW-11 Open Hole, No Screen +/- 1 second 
363709116264601 Richard Washburn Unknown +/- 1 second 
363409116233701 L. Cook Unknown +/- 1 minute 
363411116264701 Unknown Unknown +/- 5 seconds 
363428116281201 Amargosa Water Unknown +/- 5 seconds 
363429116233401 Lewis C. Cook Unknown +/- 5 seconds 
363511116335101 Unknown Unknown +/- 1 second 
365624116222901 USW UZ-N91 Open Hole, No Screen unknown

 
 I-26 
Table I-7 Accuracy of Land-surface Altitude and Latest Water-level Measurement Method Description 
Accuracy of Location/Accuracy of Land-surface Altitude (meters) 
Location and land-surface altitude accuracy, where available, were compiled from the NWIS data files (DTN: 
GS991100002330.001). 
Latest Water-level Measurement Method Description 
Typical water-level measurement method was compiled from the NWIS data files (DTN: GS991100002330.001), and from the 
Nye County datasets listed in Table 4-1. 
USGS Site ID Site Name Accuracy of Landsurface 
Altitude (m) 
Latest Water-level Measurement 
Method Description 
365629116222602 UE-29 a #2 0.1 Steel-tape measurement 
365520116370301 GEXA Well 4 0.1 Electric-tape measurement 
365340116264601 UE-25 WT #6 0.1 Steel-tape measurement 
365322116273501 USW G-2 0.1 Electric-tape measurement 
365239116253401 UE-25 WT #16 0.1 Steel-tape measurement 
365208116274001 USW UZ-14 unknown unknown 
365207116264201 UE-25 WT #18 0.1 Steel-tape measurement 
365200116272901 USW G-1 0.1 Unknown 
365147116185301 UE-25 a #3 0.1 Reported, method not known 
365140116260301 UE-25 WT #4 0.1 Steel-tape measurement 
365116116233801 UE-25 WT #15 0.1 Steel-tape measurement 
365114116270401 USW G-4 0.1 Manometer measurement 
365105116262401 UE-25 a #1 0.1 Calibrated electric-tape measurement 
365032116243501 UE-25 WT #14 0.1 Steel-tape measurement 
365023116271801 USW WT-2 0.1 Steel-tape measurement 
364947116254300 UE-25 c #1 0.1 Analog or graphic recorder 
364947116254501 UE-25 c #3 0.1 Steel-tape measurement 
364947116254401 UE-25 c #2 0.1 Reported, method not known 
364945116235001 UE-25 WT #13 0.1 Steel-tape measurement 
364933116285701 USW WT- 7 0.1 Manometer measurement 
364916116265601 USW WT- 1 0.1 Electric-tape measurement 
364905116280101 USW G-3 0.1 unknown 
364828116234001 UE-25 J -13 0.1 Steel-tape measurement 
364825116290501 USW WT-10 0.1 Electric-tape measurement 
364822116262601 UE-25 WT #17 0.1 Steel-tape measurement 
365821116343701 USW VH-2 unknown unknown 
364757116245801 UE-25 WT #3 0.1 Steel-tape measurement 
364732116330701 USW VH-1 0.1 Steel-tape measurement 
364656116261601 UE-25 WT #12 0.1 Steel-tape measurement 
364649116280201 USW WT-11 0.1 Reported, method not known 
364554116232400 UE-25 J -12 0.1 unknown 
364528116232201 UE-25 JF #3 0.1 Unknown 
364105116302601 Cind-R-Lite Well 0.1 Unknown 
363907116235701 Ben Bossingham 1.0 Reported, method not known 
363836116234001 Fred Cobb 0.5 Electric-tape measurement 
363840116235000 Bob Whellock 3.0 Reported, method not known 
363840116234001 Louise Pereidra 2.0 Reported, method not known 
363840116233501 Joe Richards 0.5 Reported, method not known 
363835116234001 NDOT Well 0.1 Steel-tape measurement

 
 I-27 
USGS Site ID Site Name Accuracy of Landsurface 
Altitude (m) 
Latest Water-level Measurement 
Method Description 
363742116263201 James H. Shaw 0.5 Steel-tape measurement 
363830116241401 Airport Well 0.1 Calibrated electric-tape measurement 
363815116175901 TW- 5 0.1 Electric-tape measurement 
363711116263701 Richard Washburn 0.1 Steel-tape measurement 
363621116263201 Richard Washburn 0.5 Reported, method not known 
363549116305001 Nye County Development Co 2.0 Steel-tape measurement 
363523116353701 Fred Wooldridge 0.5 unknown 
363525116325601 Fred J. Keefe 0.5 Electric-tape measurement 
363519116322001 Leslie Nickels 2.0 Steel-tape measurement 
363540116240801 L. Mason 1.0 Unknown 
363527116292501 Unknown 0.5 Electric-tape measurement 
363521116352501 Davidson Well 0.5 Steel-tape measurement 
363456116335501 Eugene J. Mankinen 0.5 Steel-tape measurement 
363454116314201 Donald O. Heath 0.5 Steel-tape measurement 
363503116351501 Elvis Kelley 0.5 Steel-tape measurement 
363503116284001 Manuel Rodela 0.5 Steel-tape measurement 
363436116342301 Charles C. DeFir Jr. 2.0 Electric-tape measurement 
363436116333201 William R. Monroe 2.0 Steel-tape measurement 
363434116354001 DeFir Well 0.1 Steel-tape measurement 
363438116324601 Edwin H. Mankinen 0.5 Steel-tape measurement 
363442116363301 Bill Strickland 0.5 Reported, method not known 
363440116282401 M. Meese 0.1 unknown 
363415116275101 Theo E. Selbach 0.5 Reported, method not known 
363407116342501 C.L. Caldwell 2.0 unknown 
363407116243501 Leonard Siegel 1.0 Steel-tape measurement 
363429116315901 James K. Pierce 0.5 Steel-tape measurement 
363405116321501 James K. Pierce 2.0 Steel-tape measurement 
363428116240301 Cooks West Well 2.0 Steel-tape measurement 
363428116234701 Cooks East Well 0.1 Calibrated electric-tape measurement 
363417116271801 Nye County Land Company 0.1 unknown 
363411116272901 Amargosa Town Complex 0.5 Reported, method not known 
363410116261101 Nye County Development Co 0.5 Steel-tape measurement 
363410116240301 Lewis C. Cook 0.5 Steel-tape measurement 
363410116240001 Lewis C. Cook 1.0 Steel-tape measurement 
363407116273301 Amargosa Valley Water 0.5 Reported, method not known 
363342116335701 Earl N. Selbach 0.5 Reported, method not known 
363340116332901 Lewis N. Dansby 2.0 Steel-tape measurement 
363342116325101 Edwin H. Mankinen 2.0 Unknown 
363350116252101 Willard Johns 0.5 Steel-tape measurement 
365157116271202 USW H-1 tube 1 0.1 Steel-tape measurement 
365157116271203 USW H-1 tube 2 0.1 Steel-tape measurement 
365157116271204 USW H-1 tube 3 0.1 Steel-tape measurement 
365157116271205 USW H-1 tube 4 0.1 Steel-tape measurement 
365122116275502 USW H-5 upper 0.1 Steel-tape measurement 
365122116275503 USW H-5 lower 0.1 Steel-tape measurement 
365108116262302 UE-25 b #1 lower 0.1 Steel-tape measurement 
365108116262303 UE-25 b #1 upper 0.1 Steel-tape measurement 
365049116285502 USW H-6 upper 0.1 Steel-tape measurement 
365049116285505 USW H-6 lower 0.1 unknown

 
 I-28 
USGS Site ID Site Name Accuracy of Landsurface 
Altitude (m) 
Latest Water-level Measurement 
Method Description 
365032116265402 USW H-4 upper 0.1 Unknown 
365032116265403 USW H-4 lower 0.1 Steel-tape measurement 
364942116280002 USW H-3 upper 0.1 Steel-tape measurement 
364942116280003 USW H-3 lower 0.1 Calibrated electric-tape measurement 
364938116252102 UE-25 p #1(Lwr Intrvl) 0.1 Steel-tape measurement 
not available yet USW SD-7 unknown unknown 
not available yet USW SD-9 unknown unknown 
not available yet USW SD-12 unknown unknown 
364234116351501 NC-EWDP-1DX, shallow unknown Calibrated electric-tape measurement 
364234116351501 NC-EWDP-1DX, deep unknown Calibrated electric-tape measurement 
364233116351501 NC-EWDP-1S, probe 1 unknown Calibrated transducer 
364233116351501 NC-EWDP-1S, probe 2 unknown Calibrated transducer 
363939116275401 NC-EWDP-2D unknown Calibrated electric-tape measurement 
363940116275501 NC-EWDP-2DB unknown Calibrated electric-tape measurement 
364054116321401 NC-EWDP-3D unknown Calibrated electric-tape measurement 
364054116321301 NC-EWDP-3S, probe 2 unknown Calibrated transducer 
364054116321301 NC-EWDP-3S, probe 3 unknown Calibrated transducer 
363925116241501 NC-EWDP-4PA unknown Calibrated electric-tape measurement 
363925116241401 NC-EWDP-4PB unknown Calibrated electric-tape measurement 
364012116223401 NC-EWDP-5SB unknown Calibrated electric-tape measurement 
364332116332201 NC-EWDP-7S unknown Calibrated electric-tape measurement 
364145116334401 NC-EWDP-9SX, probe 1 unknown Calibrated transducer 
364145116334401 NC-EWDP-9SX, probe 2 unknown Calibrated transducer 
364145116334401 NC-EWDP-9SX, probe 4 unknown Calibrated transducer 
364137116351001 NC-EWDP-12PA unknown Calibrated electric-tape measurement 
364138116351001 NC-EWDP-12PB unknown Calibrated electric-tape measurement 
364139116351001 NC-EWDP-12PC unknown Calibrated electric-tape measurement 
364011116294901 NC-EWDP-15P unknown Calibrated electric-tape measurement 
364015116265301 NC-EWDP-19P unknown Calibrated electric-tape measurement 
364014116265301 NC-EWDP-19D unknown Calibrated electric-tape measurement 
365301116271301 USW WT-24 unknown Steel-tape measurement 
363951116252401 NC-Washburn-1X unknown Calibrated electric-tape measurement 
364706116170601 UE-25 J -11 0.1 Calibrated electric-tape measurement 
364237116365401 BGMW-11 0.5 Steel-tape measurement 
363709116264601 Richard Washburn 0.5 Steel-tape measurement 
363409116233701 L. Cook 0.1 Reported, method not known 
363411116264701 Unknown 0.1 Steel-tape measurement 
363428116281201 Amargosa Water 0.5 Steel-tape measurement 
363429116233401 Lewis C. Cook 1.0 Steel-tape measurement 
363511116335101 Unknown 0.5 Steel-tape measurement 
365624116222901 USW UZ-N91 unknown Steel-tape measurement

 
 I-29 
Table I-8 Water Level Measurement Accuracy and Perched? 
Water-level Measurement Accuracy 
Water-level altitude accuracy, where available, was compiled from the NWIS data files (DTN: GS991100002330.001). 
Perched? 
Potential perched-water levels identified during this analysis were flagged and identified as Suspected perched or Assumed 
perched. 
USGS Site ID Site Name Water Level 
Measurement Accuracy Perched? 
365629116222602 UE-29 a #2 Nearest 0.01 feet. Suspected perched 
365520116370301 GEXA Well 4 Nearest 0.01 feet. 
365340116264601 UE-25 WT #6 Nearest 0.01 feet. Assumed perched 
365322116273501 USW G-2 unknown Assumed perched 
365239116253401 UE-25 WT #16 Nearest 0.01 feet. 
365208116274001 USW UZ-14 unknown 
365207116264201 UE-25 WT #18 Nearest 0.01 feet. Suspected perched 
365200116272901 USW G-1 unknown Suspected perched 
365147116185301 UE-25 a #3 Nearest foot. Suspected perched 
365140116260301 UE-25 WT #4 Nearest 0.01 feet. 
365116116233801 UE-25 WT #15 Nearest 0.01 feet. 
365114116270401 USW G-4 Nearest 0.01 feet. 
365105116262401 UE-25 a #1 unknown 
365032116243501 UE-25 WT #14 Nearest 0.01 feet. 
365023116271801 USW WT-2 Nearest 0.01 feet. 
364947116254300 UE-25 c #1 Nearest 0.01 feet. 
364947116254501 UE-25 c #3 Nearest 0.01 feet. 
364947116254401 UE-25 c #2 Nearest foot. 
364945116235001 UE-25 WT #13 Nearest 0.01 feet. 
364933116285701 USW WT- 7 Nearest 0.01 feet. 
364916116265601 USW WT- 1 Nearest 0.1 feet. 
364905116280101 USW G-3 unknown 
364828116234001 UE-25 J -13 Nearest 0.01 feet. 
364825116290501 USW WT-10 Nearest foot. 
364822116262601 UE-25 WT #17 Nearest 0.01 feet. 
365821116343701 USW VH-2 unknown 
364757116245801 UE-25 WT #3 Nearest 0.01 feet. 
364732116330701 USW VH-1 Nearest 0.01 feet. 
364656116261601 UE-25 WT #12 Nearest 0.01 feet. 
364649116280201 USW WT-11 Nearest foot. 
364554116232400 UE-25 J -12 Nearest 0.01 feet. 
364528116232201 UE-25 JF #3 unknown 
364105116302601 Cind-R-Lite Well Nearest 0.1 feet. 
363907116235701 Ben Bossingham Nearest foot. 
363836116234001 Fred Cobb Nearest 0.1 feet. 
363840116235000 Bob Whellock Nearest foot. 
363840116234001 Louise Pereidra Nearest foot. 
363840116233501 Joe Richards Nearest foot. 
363835116234001 NDOT Well Nearest 0.01 feet. 
363742116263201 James H. Shaw Nearest 0.01 feet.

 
 I-30 
USGS Site ID Site Name Water Level 
Measurement Accuracy Perched? 
363830116241401 Airport Well Nearest 0.01 feet. 
363815116175901 TW- 5 Nearest 0.01 feet. 
363711116263701 Richard Washburn Nearest 0.01 feet. 
363621116263201 Richard Washburn Nearest foot. 
363549116305001 Nye County Development Co Nearest 0.01 feet. 
363523116353701 Fred Wooldridge Nearest 0.1 feet. 
363525116325601 Fred J. Keefe Nearest 0.1 feet. 
363519116322001 Leslie Nickels Nearest 0.01 feet. 
363540116240801 L. Mason Nearest 0.01 feet. 
363527116292501 Unknown Nearest 0.1 feet. 
363521116352501 Davidson Well Nearest 0.01 feet. 
363456116335501 Eugene J. Mankinen Nearest 0.01 feet. 
363454116314201 Donald O. Heath Nearest 0.01 feet. 
363503116351501 Elvis Kelley Nearest 0.01 feet. 
363503116284001 Manuel Rodela Nearest 0.01 feet. 
363436116342301 Charles C. DeFir Jr. Nearest 0.1 feet. 
363436116333201 William R. Monroe Nearest 0.01 feet. 
363434116354001 DeFir Well Nearest 0.01 feet. 
363438116324601 Edwin H. Mankinen Nearest 0.01 feet. 
363442116363301 Bill Strickland Nearest foot. 
363440116282401 M. Meese Nearest 0.01 feet. 
363415116275101 Theo E. Selbach Nearest foot. 
363407116342501 C.L. Caldwell Nearest foot. 
363407116243501 Leonard Siegel Nearest 0.01 feet. 
363429116315901 James K. Pierce Nearest 0.01 feet. 
363405116321501 James K. Pierce Nearest 0.01 feet. 
363428116240301 Cooks West Well Nearest 0.01 feet. 
363428116234701 Cooks East Well Nearest 0.01 feet. 
363417116271801 Nye County Land Company Nearest 0.1 feet. 
363411116272901 Amargosa Town Complex Nearest foot. 
363410116261101 Nye County Development Co Nearest 0.01 feet. 
363410116240301 Lewis C. Cook Nearest 0.01 feet. 
363410116240001 Lewis C. Cook Nearest 0.01 feet. 
363407116273301 Amargosa Valley Water Nearest foot. 
363342116335701 Earl N. Selbach Nearest foot. 
363340116332901 Lewis N. Dansby Nearest 0.01 feet. 
363342116325101 Edwin H. Mankinen Nearest 0.01 feet. 
363350116252101 Willard Johns Nearest 0.01 feet. 
365157116271202 USW H-1 tube 1 Nearest 0.01 feet. 
365157116271203 USW H-1 tube 2 Nearest 0.01 feet. 
365157116271204 USW H-1 tube 3 Nearest 0.01 feet. 
365157116271205 USW H-1 tube 4 Nearest 0.01 feet. 
365122116275502 USW H-5 upper Nearest 0.01 feet. 
365122116275503 USW H-5 lower Nearest 0.01 feet. 
365108116262302 UE-25 b #1 lower Nearest 0.01 feet. 
365108116262303 UE-25 b #1 upper Nearest 0.01 feet. 
365049116285502 USW H-6 upper Nearest 0.01 feet. 
365049116285505 USW H-6 lower unknown 
365032116265402 USW H-4 upper unknown

 
 I-31 
USGS Site ID Site Name Water Level 
Measurement Accuracy Perched? 
365032116265403 USW H-4 lower Nearest 0.01 feet. 
364942116280002 USW H-3 upper Nearest 0.01 feet. 
364942116280003 USW H-3 lower unknown 
364938116252102 UE-25 p #1(Lwr Intrvl) Nearest 0.01 feet. 
not available yet USW SD-7 unknown 
not available yet USW SD-9 unknown 
not available yet USW SD-12 unknown 
364234116351501 NC-EWDP-1DX, shallow unknown 
364234116351501 NC-EWDP-1DX, deep unknown 
364233116351501 NC-EWDP-1S, probe 1 unknown 
364233116351501 NC-EWDP-1S, probe 2 unknown 
363939116275401 NC-EWDP-2D unknown 
363940116275501 NC-EWDP-2DB unknown 
364054116321401 NC-EWDP-3D unknown 
364054116321301 NC-EWDP-3S, probe 2 unknown 
364054116321301 NC-EWDP-3S, probe 3 unknown 
363925116241501 NC-EWDP-4PA unknown 
363925116241401 NC-EWDP-4PB unknown 
364012116223401 NC-EWDP-5SB unknown 
364332116332201 NC-EWDP-7S unknown Assumed perched 
364145116334401 NC-EWDP-9SX, probe 1 unknown 
364145116334401 NC-EWDP-9SX, probe 2 unknown 
364145116334401 NC-EWDP-9SX, probe 4 unknown 
364137116351001 NC-EWDP-12PA unknown 
364138116351001 NC-EWDP-12PB unknown 
364139116351001 NC-EWDP-12PC unknown 
364011116294901 NC-EWDP-15P unknown 
364015116265301 NC-EWDP-19P unknown 
364014116265301 NC-EWDP-19D unknown 
365301116271301 USW WT-24 Nearest 0.01 feet. 
363951116252401 NC-Washburn-1X unknown 
364706116170601 UE-25 J -11 Nearest 0.01 feet. 
364237116365401 BGMW-11 Nearest 0.01 feet. 
363709116264601 Richard Washburn Nearest 0.01 feet. 
363409116233701 L. Cook Nearest foot. 
363411116264701 Unknown Nearest 0.01 feet. 
363428116281201 Amargosa Water Nearest 0.01 feet. 
363429116233401 Lewis C. Cook Nearest 0.01 feet. 
363511116335101 Unknown Nearest 0.01 feet. 
365624116222901 USW UZ-N91 Nearest 0.01 feet. Suspected perched