Us 93 Hoover Dam Bypass Project: Final Environmental Impact Statement And Section 4 (F) Evaluation, Volume 1


                     300R05903A
FHWA-AZNV-EIS-98-03-F
U.S. 93 Hoover Dam
     ass Project
      mental Impact Statement
     ction 4(f) Evaluation
      I
     ighway Administration

     eral Lands Highway Division

-------
s\

-------
FHWA-AZNV-EIS-98-03-F

U.S. 93 Hoover Dam Bypass
Final
Environmental Impact Statement
and Section 4(f) Evaluation

Submitted Pursuant to 42 U.S.C 4332 (2) (c), 49 U5.C 303, and Section 404
-------
This page intentionally left blank.
SCO/EIR-4F.WPD/003672769
-------
Preface
This Final Environmental Impact Statement (FE1S) consists of the complete text of the Draft
EIS (DEIS) with revisions and additions based on supplemental research and public and
agency comments. Substantive revisions to the DEIS are marked in this FEIS by a vertical
line in the outside margin next to the revised or added text. The FEIS includes a new
Volume n, which describes the DEIS notification and public hearing process, summarizes
and reproduces all comments received on the DEIS, and provides responses to comments.
This FEIS is also available for review on the U.S. 93 Hoover Dam Bypass Project web site at:

wwwJiooverdambypass.org

The Federal Highway Administration - Central Federal Lands Highway Division (FHWA)
served as the lead agency in the preparation of this document. The following agencies
served as cooperating agencies: Arizona Department of Transportation, Nevada
Department of Transportation, U.S. National Park Service, U.S. Army Corps of Engineers,
U.S. Bureau of Reclamation, U.S. Coast Guard, U.S. Fish and Wildlife Service (USFWS), and
the Western Area Power Administration.

On the basis of comments received on the DEIS, FHWA has identified the Sugarloaf
Mountain Alternative, with the proposed mitigation measures incorporated herein, as the
preferred alternative. The preferred alternative was identified on the basis of minimizing
environmental impacts, engineering and operational advantages, and slightly lower
construction cost. Sections of the DEIS that have been substantively rewritten or
supplemented in response to public and agency comments consist of: Chapter 2 -
Alternatives (discussion of preferred alternative identification); Chapter 3 - Biology
(incorporation of USFWS Biological Opinion), Cultural Resources, Hazardous Materials,
and Construction Impacts; Chapter 5 - Cumulative Impacts; Chapter 6 - Section 4(f)
Evaluation; and Appendix B - Laughlin-Bullhead City Alternative.

The U.S. 93 Hoover Dam Bypass FEIS will be used by the FHWA to decide the various
discretionary actions required to implement the project. FHWA's decisions will be
identified in a Record of Decision. Statements on the FEIS will be accepted by the FHWA
and considered in the decision on this proposed action. The FEIS is being distributed for a
30-day notification period that begins on January 19,2001, and ends on February 20,2001.
SCO/PREFACE.WPD/003672768
-------
This page intentionally left blank.
SCO/PREFACE.WPD/003672768
-------
Contents
Chapter Page

Executive Summary ES-1
1 Purpose and Need 1-1
1.1 Introduction 1-1
1.2History 1-2
1.3 Previous Studies Conducted 1-7
1.4Need for the Project 1-14
1.5 Purpose of Project 1-19
1.6 Relationship of the Proposed Project to the Statewide Plan
or Urban Transportation Plan 1-20
1.7 Legislation Regarding the Proposed Project 1-21
1.8 Relationship of the Proposed Project to Other Modes of
Transportation 1-23
2 Alternatives 2-1
2.1 Introduction 2-1
2.2 Initial Identification of Alternatives 2-1
2.3 Criteria for Screening Alternatives 2-6
2.4 Public Input 2-6
2.5 Alternatives Considered but Eliminated from Detailed Evaluation 2-7
2.6 Alternatives Studied in Detail 2-9
2.7 No Build Alternative 2-36
2.8 Logical Termini 2-43
2.9Toll Option 2-43
3 Affected Environment, Environmental Consequences, and
Measures to Minimize Harm 3-1
Introduction 3-1
3.1 Air Quality 3-2
3.2 Noise 3-7
3.3 Biology 3-16
3.4 Water Resources 3-41
3.5 Cultural Resources 3-48
3.6 Land Use 3-66
3.7 Visual Resources 3-70
3.8 Recreation Resources 3-100
3.9 Socioeconomics • 3-109

SCO/CONTENTS.WPDA)03672770 v
-------
Contents, Continued
Chapter 3, Continued Page

3.10 Hazardous Materials 3-116
3.11 Construction Activities and Impacts 3-125
3.12 Energy 3-145
3.13 Local Short-Term Uses Versus Long-Term Productivity 3-146
3.14 Irreversible and Irretrievable Commitment of Resources 3-147
4 Unavoidable Adverse Impacts 4-1
4.1 Introduction 4-1
4.2 Air 4-1
4.3 Noise 4-1
4.4 Biological Resources 4-1
4.5 Water Resources 4-1
4.6 Cultural Resources 4-2
4.7 Land Use 4-3
4.8 Visual Resources 4-3
4.9 Recreation 4-3
4.10 Socioeconomics 4-4
4.11 Hazardous Materials : 4-4
5 Cumulative Impacts 5-1
| 5.1 Introduction 5-1
| 5.2 Cumulative Impacts Analysis 5-1
5.3 Methods Used for Identifying Other Past, Present, and Reasonably
Foreseeable Actions/Projects 5-3
5.4 list of Past, Present, and Reasonably Foreseeable Actions/Projects
and Respective Environmental Impacts 5-3
| 5.5 Cumulative Environmental Impacts 5-17
6 Section 4(f) Evaluation . 6-1
Introduction 6-1
6.1 Purpose of Section 4(f) Evaluation 6-1
6.2 Proposed Project 6-2
6.3 Section 4(f) Properties 6-6
6.4 Impacts on the Section 4(f) Properties 6-9
6.5 Avoidance Alternatives 6-20
| 6.6 Justification for Use of Section 4(f) Land 6-23
6.7 Measures to Minimize Harm 6-27

vi SCO/CONTENTS.WPD/003672770
-------
Contents, Continued
Chapter 6, Continued Page

6.8 Coordination 6-31
6.9 Determination 6-32 |
7 Coordination and Consultation 7-1
7.1 Introduction 7-1
7.2 Public Scoping 7-2
7.3 Public Comment Meetings 7-2
7.4 Public Agency Partnering Session Held October 29,1997 7-3
7.5 Project Management Team Meetings 7-3
7.6 Public Outreach 7-3
7.7 DEIS Public Review and Comment 7-3
7.8 Consultation with Native American Tribes 7-4 |
7.9 Permits 7-5
8 list of Report Preparers 8-1
9 References 9-1
10 List of Agencies, Organizations, and Persons to Whom Copies of the
Environmental Impact Statement were Sent 10-1
Index Index-1

Appendixes

Appendix A Traffic Analysis
Appendix B Laughlin-Bullhead City Alternative
Appendix C Correspondence
Appendix D U.S. Army Corps of Engineers Section 404(b)(l) Guidelines
Appendix E U.S. Fish and Wildlife Service Biological Opinion |

Tables Page
ES-1 Summary of Environmental Impacts ES-4
ES-2 Permits and Approvals Anticipated for the Hoover Dam Bypass Project ES-9
ES-3 Summary of Mitigation Measures ES-9
1-1 Previous U.S. Highway 93 and Hoover Dam Studies 1-7
1-2 Traffic Volumes and Level of Service at Hoover Dam 1-15
1-3 Accident Data for 1994 to 1997 1-16
SCO/CONTENTS.WPD/003672770 vii
-------
Contents, Continued
Tables, Continued Page

2-1 Comparison of Alternatives Considered 2-10
| 2-2 Hoover Dam Bypass - U.S. 93 Alternative Preference by Individual Criteria ... 2-30
3-1 Attainment Status 3-3
3-2 Existing Traffic Conditions 3-4
3-3 Estimated 1997 Vehicle Emission Rates 3-4
3-4 Existing Project Burden 3-5
3-5 Daily Emissions by Alternative 3-6
3-6 Federal Highway Administration Design Noise Level/Activity Relationships .. 3-8
3-7 Measured Noise Levels (dBA-L^,) 3-8
3-8 Existing Peak-Hour Noise Levels (dBA-L^) 3-9
3-9 Estimated Peak Construction Noise Levels (dBA) 3-10
3-10 Future Peak-Hour Noise Levels (dBA-L^) 3-13
3-11 Gold Strike Canyon Alternative Future Peak-Hour Noise Levels (dBA-Leq) 3-15
3-12 Special-status Vegetation and Wildlife Species Potentially Occurring in the
Proposed Project Area and Likelihood of Occurrence 3-23
3-13 Comparison of Impacts to General Terrestrial Communities from All
Alternatives (Colorado River Bridge - Hoover Dam) 3-26
3-14 Comparison of Impacts of All Alternatives to Special-Status Species 3-28
3-15 Comparison of Impacts of Build Alternatives on Desert Bighorn Sheep 3-31
3-16 Acreage of Permanent and Temporary Fill in Waters of the United States
for Each Alignment 3-32
3-17 Estimated Number of Wildlife Crossing Structures for Each Alternative 3-34
3-18 Acreage to be Developed for Each Build Alternative 3-69
3-19 1990 Census Data by Locality Near the Proposed Project Area 3-110
3-20 Average Annual Daily Traffic and Level of Service at Hoover Dam 3-113
3-21 Forecasted Average Annual Daily Traffic and Level of Service at Hoover Dam
Under No Build Alternative 3-115
3-22 Estimated Construction Period for Build Alternatives 3-126
6-1 Section 4(f) Impacts of the Hoover Dam Bypass Project 6-11
6-2 Gold Strike Canyon Alternative Mitigated Future
Peak-Hour Noise Levels (dB A-L^) 6-30
7-1 Permits and Approvals Anticipated for the Hoover Dam Bypass Project 7-5
VIII
SCO/CONTENTS.WPD/003672770
-------
Contents, Continued
Figures Page

1-1 U.S. 93 Transportation Corridor ... 1-3
1-2 Existing Alternate Routes to U.S. 93 and Hoover Dam Crossing 1-5
1-3 Level of Service Classifications 1-17
2-1 Alternatives Considered 2-3
2-2 Typical Roadway Section 2-11
2-3 Alternatives Being Evaluated in Detail 2-13
2-4 Promontory Point Project Features 2-17
2-5 Promontory Point Suspension Bridge 2-19
2-6 Promontory Point Cable-Stayed Bridge 2-21
2-7 Promontory Point Steel Truss Rib Through Arch Bridge 2-23
2-8 Sugarloaf Mountain Project Features 2-25
2-9 Sugarloaf Mountain Concrete or Steel Arch Bridge 2-31
2-10 Sugarloaf Mountain Cable-Stayed Bridge 2-33
2-11 Gold Strike Canyon Project Features 2-37
2-12 Gold Strike Canyon Concrete Arch Bridge 2-39
2-13 Gold Strike Canyon Steel Arch Bridge 2-41
3-1 Noise Receptor Sites and Recommended Mitigation 3-11
3-2 Location of Sensitive Biological Resources 3-17
3-3 Locations of Waters of the United States Potentially Impacted
By Each Alignment 3-21
3-4 Viewpoints for Visual Simulations 3-77
3-5 Promontory Point Alternative Visual Simulations 3-79
3-6 Promontory Point Alternative Visual Simulations 3-81
3-7 Promontory Point Alternative Visual Simulations 3-83
3-8 Promontory Point Alternative Visual Simulations 3-85
3-9 Sugarloaf Mountain Alternative Visual Simulations 3-87
3-10 Sugarloaf Mountain Alternative Visual Simulations 3-89
3-11 Gold Strike Canyon Alternative Visual Simulations 3-91
3-12 Gold Strike Canyon Alternative Visual Simulations 3-93
3-13 Potential Hazardous Waste Sites 3-117
3-14A Transmission Line Removal and Relocation Option #1 3-129 |
3-14B Transmission Line Removal and Relocation Option #2 3-131 |
3-14C Transmission Line Removal and Relocation Option #3 3-133 |
3-14D Transmission Line Removal and Relocation Option #4 3-135 |

SCO/CONTENTS.WPD/003672770 ix
-------
Contents, Continued
Figures, Continued Page

| 3-14E Transmission Line Removal and Relocation Option #5 3-137
| 3-14F Transmission Line Removal and Relocation Option #5A 3-139
| 3-14G Transmission Line Removal and Relocation Option #6 3-141
| 3-15 Construction Staging Areas 3-143
6-1 Lake Mead National Recreation Area 6-7
6-2 Section 4(f) Public Recreation Lands 6-13
SCO/CONTENTS.WPD/003672770
-------
Acronyms and Abbreviations
AADT average annual daily traffic
AASHTO American Association of State Highway and Transportation Officials
ACHP Advisory Council on Historic Preservation
ACOE United States Department of the Army, Corps of Engineers
A.D. anno Domini
ADA Americans with Disabilities Act
ADEQ Arizona Department of Environmental Quality
ADOT Arizona Department of Transportation
ADT average daily traffic
AGFD Arizona Game and Fish Department
ANSI American National Standards Institute
APE area of potential effects
APP Aquifer Protection Permit
AQRV air quality-related value
ARPA Archaeological Resources Protection Act of 1979
ASC Arizona Species of Concern
ASTIP Arizona State Transportation Improvement Plan
ATR automatic traffic recorder
BA Biological Assessment
BARA Bureau of Applied Research in Anthropology
BIA Bureau of Indian Affairs
BMP Best Management Practice
B.P. Before Present (before 1950)
CAA Clean Air Act
CAP Central Arizona Project
CCDCP Clark County Desert Conservation Program
CEQ Council on Environmental Quality
CERCLA Comprehensive Environmental Response, Compensation, and
Liability Act
CFLHD Central Federal Lands Highway Division
CFR Code of Federal Regulations
CO carbon monoxide
CPI Consumer Price Index
SCO/VN-ACRON.WPD/003672771
XI
-------
ACRONYMS AND ABBREVIATIONS

CPI-U Consumer Price Index for All Urban Customers
dBA decibels on the A-scale
DCS Design Concept Study
DEIS Draft Environmental Impact Statement
DOE Department of Energy
DOI U.S Department of the Interior
DOT Department of Transportation
EA Environmental Assessment
EIS Environmental Impact Statement
e-mail electronic mail
EO Executive Order
EPA U.S. Environmental Protection Agency
°F degrees Fahrenheit
FE Federally-Listed Endangered
FEIS Final Environmental Impact Statement
FEMA Federal Emergency Management Agency
FHWA Federal Highway Administration
FIA Federal Insurance Administration
FONSI Finding of No Significant Impact
FSC Federal Species of Concern
FT Federally-Listed Threatened
GCVTC Grand Canyon Visibility Transport Commission
GMP General Management Plan
g/VMT grams per vehicle mile traveled
HABS Historic American Building Survey
HAER Historic American Engineering Record
HCS Highway Capacity Software
HDNHL Hoover Dam National Historic Landmark
HDR Hoover Dam Reservation
HDRA Hoover Dam Reservation Area
I-10 Interstate 10
1-15 Interstate 15
1-19 Interstate 19
1C Interchange
vij SCO/VN-ACRON.WPD/003672771
-------
ACRONYMS AND ABBREVIATIONS

ISTEA Intermodal Surface Transportation Efficiency Act
ITS Intelligent Transportation Systems
km kilometer
kV kilovolt
LBA Laughlin-Bullhead City Alternative
LCA Laughlin Crossing Alignment
L^ equivalent sound pressure levels
LMNRA Lake Mead National Recreation Area
LOS level of service
LWCF Land and Water Conservation Fund Act
M Monitoring
MOA Memorandum of Agreement
MOU Memorandum of Understanding
MP mile post
mpg miles per gallon
mph miles per hour
MSCP Multi-Species Conservation Program
NAAQS National Ambient Air Quality Standards
NAFTA North American Free Trade Agreement
NAGPRA Native American Graves Protection and Repatriation Act of 1990
NDOT Nevada Department of Transportation
NDOW Nevada Division of Wildlife
NEPA National Environmental Policy Act
NFIP National Flood Insurance Program
NHL National Historic Landmark
NHPA National Historic Preservation Act of 1966, as amended
NO2 nitrogen dioxide
NOX nitrogen oxides
NP Nevada protected
NPDES National Pollution Discharge Elimination System
NPS National Park Service
NRA National Recreation Area
NRHP National Register of Historic Places
OHWM ordinary high water mark
SCO/VN-ACRON.WPD/003672771 xMi
-------
ACRONYMS AND ABBREVIATIONS
OSHA
PA
Pb
PCB
PM10
PM2.5
PMT
ppm
PSD
R
RCRA
Reclamation
Reservation
ROD
ROW
RV
SFHA
SHPO
SIP
S02
SOX
SR
STIP
TCLP
TCP
TDS
TSCA
TSM
TVA
U.S.
U.S. 93
U.S. 95
USDOT
USFWS
Occupational Safety and Health Administration
Programmatic Agreement
lead
polychlorinated biphenyl
particulate matter with diameter less than 10 microns
partlculate matter with diameter less than 2.5 microns
project management team
parts per million
prevention of significant determination
receptor
Resource Conservation and Recovery Act
Bureau of Reclamation
Hoover Dam Reservation
Record of Decision
right-of-way
recreational vehicle
Special Flood Hazard Area
State Historic Preservation Officer
State Implementation Plan
sulphur dioxide
sulphur oxides
State Route
Statewide Transportation Improvement Program
toxicity characteristic leaching procedure
Traditional Cultural Property
total dissolved solids
Toxic Substances Control Act
Traffic Systems Management
Tennessee Valley Authority
United States
United States Highway 93
United States Highway 95
United States Department of Transportation
U.S. Fish and Wildlife Service
XIV
SCO/VN-ACRON.WPD/003672771
-------
ACRONYMS AND ABBREVIATIONS
UST underground storage tank
V/C volume to capacity
VMT vehicle mile traveled
VOC volatile organic compound
WAPA Western Area Power Administration
WDM Wetland Delineation Manual
SCO/VN-ACRON.WPD/003672771 xv
-------
ACRONYMS AND ABBREVIATIONS
This page intentionally left blank.
xvi SCO/VN-ACRON.WPD/003672771
-------
Executive Summary
Introduction

United States Highway 93 (U.S. 93) is part of the major transportation network in the
western United States and has been designated as a North American Free Trade Agreement
(NAFTA) route. The CANAMEX (Canada-Mexico) Corridor was formally designated a
high-priority corridor by the National Highway System Designation Act of 1995. However,
it cannot accommodate all of me traffic where it crosses over the top-of Hoover Dam. To
remedy this, the Federal Highway Administration (FHWA), in cooperation with affected
state and federal agencies,1 proposes to bypass Hoover Dam with a new bridge crossing of
the Colorado River. This Environmental Impact Statement (EIS) describes the baseline
conditions, anticipated impacts, and recommended mitigation. It was prepared in
accordance with FHWA guidelines and the provisions of the National Environmental
Policy Act (NEPA).

Scoping and Public Involvement

In 1989, the Bureau of Reclamation (Reclamation) created the "Colorado River Bridge
Project Management Team" (PMT). The focus of the PMT was to perform engineering and
environmental studies, to develop funding agreements, and to manage the design and
construction of the new crossing. The PMT is still guiding the project and is made up of
Reclamation, the FHWA, Arizona and Nevada Departments of Transportation, Western
Area Power Administration (WAPA), and the National Park Service (NPS).

In May 1990, a Notice of Intent was published in the Federal Register initiating the EIS by
Reclamation as lead agency and beginning the scoping process. Public scoping meetings
were held in June 1990 in Kingman, Arizona, and Boulder City and Las Vegas, Nevada. In
Boulder City, there was general concurrence that a new crossing was needed to remove
traffic from Hoover Dam; however, some preferred to have a bypass around Boulder City in
addition to Hoover Dam, while others felt that any road that bypassed Boulder City would
severely impact downtown businesses. A newsletter, titled Update, was published in
January 1991 and sent to interested individuals. Interviews with numerous community
members and several meetings with interested members of the public, the Boulder City
Chamber of Commerce, members of the Boulder City Council, and other organizations also
occurred.
Prior to completion of the Draft Environmental Impact Statement (DEIS), Reclamation
withdrew from the project as the lead agency in 1993. Reclamation's emphasis changed
from construction of major public works projects to water resource management. With no
lead agency or funding to continue the environmental process for a new crossing, the
project was officially put on hold in 1995.
1 Arizona Department of Transportation, Nevada Department of Transportation, National Park
Service, U.S. Army Corps of Engineers, Bureau of Reclamation, U.S. Coast Guard, U.S. Fish and
Wildlife Service, and Western Area Power Administration.

SCO/CHAP-ES.WPD/003672772 ES'1
-------
EXECUTIVE SUMMARY
FHWA filed a Notice of Intent in September 1997 to announce FHWA as the new lead
agency for environmental review of the project. FHWA conducted three public open
houses to allow comment on the alternatives carried forward from the June 1990 scoping
meetings. The open houses were held in Kingman, Boulder City, and Las Vegas in late
October 1997 to provide information on the alternative alignments under consideration
and solicit input for the environmental review process. Approximately 250 people
attended. In addition to concerns about various environmental impacts from all three
locations, many of the comments from Boulder City focused on considering other
alternative crossings in addition to the three build alternatives.

FHWA completed and approved the DEIS on September 14,1998. The DEB was circulated
to the public on September 25,1998, with publication of the Notice of Availability in the
Federal Register. From October 13 to 15,1998, FHWA held DEIS public hearings on
successive evenings in Kingman, Arizona, and Boulder City and Las Vegas, Nevada.
Approximately 250 people attended the DEIS public hearings. The court reporter
transcripts of oral comments received at the hearings are included in Volume II of the
final EIS (FEIS). The entire DEIS was also accessible on the project web site; by
November 10,1998, the close of the DEIS comment period, the web site was accessed over
1,500 times. There were approximately 160 public and agency commenters on the DEIS,
including comments received after the dose of comment period. See Volume 2 for a full
description of the DEIS public input process, the comments received, and the responses to
comments.

Description of Proposed Alternatives

Along with the No Build Alternative, three build alternatives are evaluated in detail in this
document. From north to south, they are Promontory Point, Sugarloaf Mountain (the
preferred alternative), and Gold Strike Canyon. They share common termini, near MP 2.2
in Clark County, Nevada, and MP 1.7 in Mohave County, Arizona. Each alternative would
entail construction of a four-lane highway, a new steel or concrete four-lane bridge over the
Colorado River near Hoover Dam, four-lane approaches, and the approach bridges and
tunnels needed for the approximately 3.5-mile-long project. Current highway design
standards for a 60-mile-per-hour (mph) design would be required. Under the build
alternatives, commercial trucks would be restricted from Hoover Dam according to vehicle
weight or number of axles. The project would be located on lands under the jurisdiction of
the U.S. Department of the Interior, Reclamation, and NFS.

Summary of Alternatives Considered

A range of alternatives was considered, and the identification of a preferred alternative was
not made until the alternatives' impacts and comments on the DEIS and from the public
hearings were fully evaluated. The four most reasonable alternatives fully evaluated
(including the No Build Alternative) were developed to a comparable level of detail in the
DEIS so that their comparative merits could be analyzed.
ES-2 SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Cost Estimate Basis

The cost estimates shown for the alternatives studied in detail are based on the August
1992, Reclamation Phase B Study. The estimates shown in the Phase B Study were actually
computed in 1991. Therefore, costs were inflated at 4 percent per year for 11 years,
establishing a base year of 2002.

Promontory Point Alternative

The Promontory Point Alternative crosses Lake Mead about 1,000 feet upstream of Hoover
Dam. This alternative requires constructing approximately 2.7 miles of highway approach
in Nevada; a 2,200-foot-long bridge; and an approximately 0.9-mile highway approach in
Arizona. The estimated cost is $204 million for base year 2002.

Sugarloaf Mountain Alternative (Preferred Alternative)

The Sugarloaf Mountain Alternative crosses the Colorado River about 1,500 feet down-
stream of Hoover Dam. This alternative requires constructing approximately 2.2 miles of
highway approach in Nevada, a 1,900-foot-long bridge, and an approximately 1.1-mile
highway approach in Arizona. The estimated cost is $198 million for base year 2002.

Sugarloaf Mountain has been identified as the preferred alternative on the basis of
minimizing environmental impacts, engineering and operational advantages, and slightly
lower construction cost. A detailed discussion of the screening criteria used to identify the
preferred alternative is in Section 2.6.2.1.

Gold Strike Canyon Alternative

The Gold Strike Canyon Alternative crosses the Colorado River about 1 mile downstream of
Hoover Dam. This alternative requires constructing approximately 2.2 miles of highway
approach in Nevada, a 1,700-foot-long bridge, and a 1.1-mile highway approach in Arizona.
The estimated cost is $215 million for base year 2002.

No Build Alternative

The No Build Alternative is no action being taken. No Hoover Dam Bypass is developed;
no change in the current highway configuration occurs; and no other structural or nonstruc-
tural improvements are developed on U.S. 93 near Hoover Dam. Existing hairpin curves,
bottleneck conditions, inadequate sight distances, narrow dam crest roadway, and steep
grades on U.S. 93 in the Hoover Dam vicinity remain unchanged.

The No Build Alternative does not meet the project purpose and need (see Chapter 1)
because it does not decrease travel times or increase travel speeds in the vicinity of the dam.
The increased traffic, which will continue to travel at slower speeds, contributes to
decreased air quality in the Hoover Dam vicinity and increases accidents and congestion for
tourists at Hoover Dam and the Lake Mead National Recreation Area (LMNRA). The
potential for a catastrophe involving vehicles containing hazardous materials reasonably
may be expected to increase with increasing traffic volume. Risks to innocent bystanders,
property damage to the dam and its facilities, contamination of Lake Mead or the Colorado
River, and interruption of the power and water supplies to Southwest residents remains or
increases.
SCO/CHAP-ES.WPD/003672772 ES-3
-------
EXECUTIVE SUMMARY
Summary of Environmental Impacts
Table ES-1 summarizes the impacts identified for the three build alternatives and the
No Build Alternative.
Table ES-1
Summary of Environmental Impacts
Alternative
Resource
Air Quality
Promontory
Point
Construction would
Sugarloaf
Mountain
Construction would
Gold
Strike Canyon
Construction would
No Build
Air quality in the
cause an increase
in localized airborne
dust and
microscopic
particulate matter.
After mitigation, this
impact would be
reduced to an
acceptable level.

A beneficial impact
would occur after
construction
because
traffic-caused
exhaust fumes
would be reduced at
Hoover Dam.
cause an increase
in localized airborne
dust and
microscopic
particulate matter.
After mitigation, this
impact would be
reduced to an
acceptable level.

A beneficial impact
would occur after
construction
because
traffic-caused
exhaust fumes
would be reduced at
Hoover Dam.
proposed project
area would
decrease because
traffic would
continue to move
slowly over the
Hoover Dam
crossing.
Noise
Short-term noise
impacts during
construction. No
noise impact during
operation.
Short-term noise
impacts during
construction. No
noise impact during
operation.
Short-term noise
impacts during
construction. Even
with mitigation,
operation would
result in a
20-decibel increase
from existing noise
levels at the upper
end of Gold Strike
Canyon.
Noise impacts at
Hoover Dam from
increased traffic
associated with this
alternative would
exceed any of the
build alternatives.
Biological
Resources
Disturbance of
0.6 acre of desert
wash habitat.

Peregrine falcon:
breeding territory
within 1 mile of
bridge site.

Desert tortoise8:
loss of 129 acres of
marginal habitat;
may affect
B tortoises in low
density population.
Disturbance of
0.3 acre of desert
wash habitat.

Peregrine falcon:
may forage within
project area.

Desert tortoise":
loss of 120 acres of
marginal habitat;
may affect
8 tortoises in low
density population.
Disturbance of
11.0 acres of desert
wash habitat.

Peregrine falcon:
possible breeding
territory within
1 mile of bridge site.

Desert tortoise8:
loss of 131 acres of
marginal habitat;
may affect
9 tortoises in low
density population.
No impacts.
ES-4
SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Table ES-1
Summary of Environmental Impacts
Alternative
Resource
Promontory
Point
Sugartoaf
Mountain
Gold
Strike Canyon
No Build
Desert bighorn
sheep: Impact to
25 acres of lambing
habitat; access to
1 natural water
source disrupted.
Desert bighorn
sheep: impact to
20 acres of lambing
habitat; impact to
1 human-made
water source.
Desert bighorn
sheep: Impact to
55 acres of lambing
habitat; access to
3 natural water
sources disrupted.
Water
Resources

Cultural
Resources
[acreage
impacted
included under
Section 4(f)]
Erosion of cut and
fill slopes; sediment
and containment
transport; and
increased surface
runoff.

Nonmitigable
adverse effect to
historic views of
Hoover Dam
(National Historic
Landmark).
Erosion of cut and
fill slopes; sediment
and containment
transport; and
Increased surface
runoff.

Mitigable adverse
effect to historic
setting of Hoover
Dam (National
Historic Landmark).

Erosion of cut and
fill slopes; sediment
and containment
transport; and
increased surface
runoff. Gold Strike
has the greatest
potential for
construction
impacts.
No adverse effect to
historic setting of
Hoover Dam
(National Historic
Landmark).

Continued danger of
major hazardous
material spill on
dam and
contamination of
lake and river
waters.

No impacts

Adverse effect on
seven historic
features eligible for
or listed in National
Register. A portion
of this route is also
located in a
traditional cultural
property.
Adverse effect on
eight historic
features eligible for
or listed in National
Register". A portion
of this route is also
located in a
traditional cultural
property.
Adverse effect on
five historic features
eligible for or listed
in National Register.
A portion of this
route is also located
in a traditional
cultural property.
Section 4(f)
74 acres of
Section 4(f) lands
would be impacted.
Potential spill in lake
could impact
additional
thousands of acres
of recreational
waters in LMNRA.
Adversely impacts
historic "first
impression" views of
the landmark.
92 acres of
Section 4(f) lands
would be impacted.
128 acres of
Section 4(0 lands
would be impacted.
No impacts.
SCO/CHAP-ES.WPD/003672772
ES-5
-------
EXECUTIVE SUMMARY
Table ES-1
Summary of Environmental Impacts
Alternative
Resource
Visual
Resources
Recreation
Resources
[acreage impact
included under
Section 4(f)]
Promontory
Point
Would alter view of
Lake Mead and
upstream landf onms
from dam and
adjacent shores.
Restrictions on
recreation activities
within construction
safety zone during
construction.
Sugarloaf
Mountain
Would alter view of
downstream
landforms from dam
and of Hoover Dam
from the river and
adjacent shores.
Restrictions on
recreation activities
within construction
safety zone during
construction.
Gold
Strike Canyon
Would alter views of
Gold Strike Canyon
and Black Canyon.
Bridge would not be
visible from Hoover
Dam.
Restrictions on
recreation activities
within construction
safety zone during
construction.
No Build
No impacts.
Increased traffic at
the dam would
diminish the quality
of recreational
experience.
Minor effect on
rafting concessions
during construction.
Effect on river
rafting, rock
climbing, nature
study, and hiking.
Canyon Trail closed
for 5- to 6-year
construction period.
New bridge would
become a tourist
attraction.
New bridge would
become a tourist
attraction.
Socio-
economics
Hazardous
Materials
Beneficial impacts
from improvements
to transportation
and circulation.
Impacts
Reclamation
Beneficial impacts
from improvements
to transportation
and circulation.
Impacts
Reclamation
Beneficial impacts
from improvements
to transportation
and circulation.
Impacts the Nevada
Spoil Pile, which
Adverse impact on
transportation and
circulation. Bene-
ficial impacts
associated with a
build alternative
would not occur.
See Water
Resources.
warehouse storage
yard, which has
known past and
present use and
storage of
chemicals, and
leaking underground
fuel storage tanks;
impacts two
contractor staging
and disposal areas
where
petrochemicals were
stored; impacts
dump pile, from
original dam
construction, with
rusted metal drums
and scrap; also
warehouse storage
yard, which has
known past and
present use and
storage of
chemicals, and
leaking
underground fuel
storage tanks;
impacts two
contractor staging
and one disposal
area where
petrochemicals
were stored;
possibly impacts
Arizona-Nevada
Switchyard, with
noted ground
has numerous metal
drums, potential
asbestos-containing
roofing material,
and potential
contamination from
chemical releases.
ES-6
SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Table ES-1
Summary of Environmental Impacts
Alternative
Resource
Promontory
Point
Sugarloaf
Mountain
Gold
Strike Canyon
No Build
impacts abandoned staining and
switchyard with potential PCB
potential contamination in
polychlorinated soil; also impacts
biphenyl (PCB) Reclamation
contamination In sewage ponds with
soil. potential industrial
wastewater
contamination.
a These are combined impacts to both Mojave (Nevada) and Sonoran (Arizona) desert tortoises. For the
federally listed threatened Mojave desert tortoise, the following impacts would occur: Promontory Point -
95 acres of habitat and 6 tortoises lost; Sugarloaf Mountain - 80 acres of habitat and 5 tortoises lost; and
Gold Strike Canyon - 89 acres of habitat and 5 tortoises lost.
" An additional, comprehensive historic resources survey was conducted on the Sugartoaf Mountain alignment
after it was identified as the preferred alternative, resulting in recordation of seven additional historic features
relating to the construction and operation of Hoover Dam. Two of the eight impacted sites would be affected
only by a change in historic setting.

Section 4(f) Evaluation

Section 4(f) of the U.S. Department of Transportation Act of 1966, codified in federal law at
49 U.S.C. § 303, declares, "It is the policy of the United States government that special effort
should be made to preserve the natural beauty of the countryside and public park and
recreation land, wildlife and waterfowl refuges, and historic sites." Section 4(f) specifies,
"The Secretary [of Transportation] may approve a transportation program or
project...requiring the use of publicly owned land of a public park, recreation area, or
wildlife and waterfowl refuge of national, State, or local significance, or land of an historic
site of national, State, or local significance (as determined by the Federal, State, or local
officials having jurisdiction over the park, area, refuge, or site), only if:

1. There is no feasible and prudent alternative to using that land; and

2. The program or project includes all possible planning to minimize harm to the park,
recreation area, wildlife and waterfowl refuge, or historic site resulting from the use."

Initial alternatives that avoid Section 4(f) land were determined to be unfeasible and
imprudent due to: (1) the geographic extent of LMNRA and the location of the proposed
project; (2) unfeasible engineering economics; (3) not accomplishing the project purpose and
need; and (4) imprudent increases in travel time, user costs, and environmental impacts.

Alternatives using Section 4(f) land were then screened to determine the least-harm
alternative based on the amount of area used, the location of the portion used, severity of
the portion used, and the function of the portion used. The alternatives south of the
Sugarloaf Mountain alignment to Cottonwood Cove and the Temple Bar Alternative were
eliminated based on extensive impact to essentially undisturbed Section 4(f) land. The
Laughlin-Bullhead City Alternative was eliminated because it does not meet the purpose
and need and it would cost an additional $1.4 billion in 20-year total costs. Modifications to

SCO/CHAP-ES.WPD/003672772 ES-7
-------
EXECUTIVE SUMMARY
the crest of Hoover Dam would not meet the purpose and need and would result in direct
physical alteration of the Hoover Dam National Historic Landmark. The remaining
alternatives are therefore Sugarloaf Mountain and Promontory Point.

From these two, the Sugarloaf Mountain Alternative was determined to be the least harm
alternative based on the following factors:

• Strong public concern regarding hazardous materials spills in Lake Mead from the
Promontory Point Alternative

• Resource and regulatory agency support for Sugarloaf Mountain due to least impact to
wildlife, wildlife habitat, and water quality

| • No effect on the "first impression" historic views of Hoover Dam

| • Ability to more readily blend the Sugarloaf Mountain Alternative into the landscape

• Sugarloaf Mountain Alternative traverses National Register-eligible Traditional Cultural
Property (TCP) in an area of extensive disturbance

• Ability to minimize and mitigate impacts through continuing consultation and Native
American participation on the Design Advisory Panel (DAP)
Areas of Controversy
One area of controversy has been the elimination of the Willow Beach South Route as a
feasible alternative. This alternative would cross the Colorado River about 14 miles
downstream of Hoover Dam and would require constructing approximately 22.3 miles of
new highway approaches in Nevada and Arizona. This route was eliminated from further
consideration because it requires about 19 miles of additional construction, has significantly
greater environmental impacts and impacts to Section 4(f) lands, higher costs, and potential
adverse economic impacts to Boulder City as a result of bypassing the city and diverting
traffic away from downtown businesses.

An alternative Colorado River crossing for rerouted trucks near Laughlin, Nevada, and
Bullhead City, Arizona, was initially evaluated and eliminated because the route is 23 miles
longer, has 17 more miles of steep grades than the U.S. 93 route via Hoover Dam, and fails
to meet the purpose and need for the project. It was re-evaluated in response to public
comments made during the preparation of this document. Additional analyses were
conducted (Appendix A, Traffic Analysis, and Appendix B, Laughlin-Bullhead City
Alternative Study); and it was eliminated from detailed consideration because it would not
meet the purpose and need of the project; would not reduce travel time; had much higher
operational costs; would have adverse impacts on public safety, sensitive wildlife species,
and air quality; would not protect the Hoover Dam Historic Landmark; and would not fully
address long-term traffic issues on Hoover Dam.
ES-8 SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Other Federal Actions Required for This Project
Federal actions and approvals needed for this project include those listed in Table ES-2.
Table ES-2
Permits and Approvals Anticipated for the Hoover Dam Bypass Project
Agency
Regulated Activity
Required Permit or Approval
Federal
U.S. Army Corps of Engineers

Federal Advisory Council on
Historic Preservation (ACHP)
U.S. Bureau of Reclamation

U.S. Bureau of Reclamation
National Park Service

U.S. Coast Guard

U.S. EPA
U.S. Fish and Wildlife Service
Discharge of dredge or fill material
into U.S. waters
Adverse effects on Historical and
Cultural Properties
Use of additional right-of-way for
roadway and bridge
Water use during construction
Acquisition of additional right-of-way
for roadway and bridge
Impacts on navigable waters
(Promontory Point Aft. only)

Stormwater discharges
Impacts on special-status vegetation
and wildlife species
Section 404 Permits

Programmatic Agreement (PA)
between FHWA, Nevada State
Historic Preservation Officer
(SHPO), the Arizona SHPO,
and the ACHP
Easement

Water Use Permit
Easement

Section 9 Permit

National Pollution Discharge
Elimination System (NPDES)
Permit

Biological Opinion
Summary of Mitigation Measures
Table ES-3 summarizes the measures to minimize harm identified for the three build
alternatives.

Table ES-3
Summary of Mitigation Measures' ^^
Promontory Point After-native Sugarioaf Mountain Alternative
Gold Strike Canyon Alternative
Construction
Adherence to Clark County dust
abatement permit restrictions and
requirements in state of Nevada.
Comply with ADEQ permit
stipulations for portable sources of
air pollution in Mohave County,
Arizona.

Operation
No mitigation required.
Air Quality Effects
Construction

Adherence to Clark County dust
abatement permit restrictions and
requirements in state of Nevada.
Comply with ADEQ permit
stipulations for portable sources of
air pollution in Mohave County,
Arizona.

Operation
No mitigation required.
Construction

Adherence to dark County dust
abatement permit restrictions and
requirements in state of Nevada.
Comply with ADEQ permit
stipulations for portable sources of
air pollution in Mohave County,
Arizona.

Operation
No mitigation required.
SCO/CHAP-ES.WPD/003672772
ES-9
-------
EXECUTIVE SUMMARY
Table ES-3
Summary of Mitigation Measures*
Promontory Point Alternative Sugarloaf Mountain Alternative
Gold Strike Canyon Alternative
Construction
Comply with equipment
manufacturer standards and
specifications.
Implement remedial measures in
response to specific noise
complaints.
Develop/implement blasting control
provisions and limitations.
Operation
No mitigation required.
Noise Effects

Construction
Comply with equipment
manufacturer standards and
specifications.
Implement remedial measures in
response to specific noise
complaints.
Develop/implement blasting control
provisions and limitations.
Operation
No mitigation required.
Construction
Comply with equipment
manufacturer standards and
specifications.
Implement remedial measures in
response to specific noise
complaints.
(Develop/implement blasting control
provisions and limitations.
Operation
Consider construction of noise
barriers along about 7,000 feet of
the roadway facing the canyon
trail.
Construction

Construction

Revegetate disturbed land; protect
desert washes with barriers;
construct offsite watering facilities;
build wildlife overpasses and
underpasses; place fencing along
corridor to guide bighorn sheep
and other wildlife to crossing
structures; implement monitoring
plan to assess effectiveness of
bighorn sheep mitigation;
contribute project funds to desert
tortoise habitat compensation
program; conduct preconstruction
and preblasting tortoise surveys;
relocate tortoises from construction
areas; initiate construction worker
desert tortoise education program;
remove trash to minimize predation
on tortoises; minimize destruction
of desert tortoise habitat; designate
a biologist to oversee tortoise
mitigation compliance during
construction; conduct monitoring
program of peregrine falcon
breeding pairs before/during/after
construction; restrict blasting
operations during peregrine falcon
breeding season; monitor bald
eagle use of bridge sites prior to
construction; protect bald eagle
perch sites; construct a catch net
and temporary spill containment
system, scale loose rocks prior
to/during excavation, and use
ES-10
SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Table ES-3
Summary of Mitigation Measures'
Promontory Point Alternative Sugarioaf Mountain Atternative Grtd Strike Canyon Alternative
system, scale loose rocks prior
to/during excavation, and use
netting on canyon slopes to
minimize rock-fall Impacts on
Devil's Hole pupfish, razorback
sucker, and bonytail chub;
preconstruction surveys and
possible salvage of bicolored
penstemon.
Operation
Wildlife underpasses, overpasses,
and alternate watering sources will
be maintained.
netting on canyon slopes to
minimize rock-fall impacts on Devil's
Hole pupfish, razorback sucker, and
bonytail chub; preconstruction
surveys and possible salvage of
bicolored penstemon; replace
Reclamation sewage evaporation
ponds as a wildlife watering source.

Operation
Wildlife underpasses, overpasses,
and alternate watering sources will
be maintained.
netting on canyon slopes to
minimize rock-fall impacts on
Devil's Hole pupfish, razorback
sucker, and bonytail chub;
preconstruction surveys and
possible salvage of bicolored
penstemon.
Operation
Wildlife underpasses, overpasses,
and
be maintained.
Construction
Comply with National Pollutant
Discharge Elimination System
(NPDE8) permit requirements as
necessary and appropriate;
implement best management
practices (BMPs) to reduce
potential for degrading offsite water
quality; develop extensive BMPs
for dewatering during pier
construction; construct sediment
basins to treat runoff before
discharge and for containment of
hazardous material spills; inspect
construction equipment for leakage;
locate refueling and vehicle
maintenance facilities away from
water pathways; design and
construct temporary sanitary waste
facilities to protect surface and
subsurface water resources;
construct bridge under accelerated
schedule; utilize catch net for falling
debris.
Operation
Proper design of discharge control
features; bridge runoff control/
collection system; protection of
roadside conveyance structures;
settling basins for roadway runoff
capture.
Water Resource Effects

Construction

Comply with NPDES permit
requirements as necessary and
appropriate; implement BMPs to
reduce potential for degrading
offsite water quality; construct
sediment basins to treat runoff
before discharge and for
containment of hazardous material
spills; inspect construction
equipment for leakage; locate
refueling and vehicle maintenance
facilities away from water
pathways; design and construct
temporary sanitary waste facilities
to protect surface and subsurface
water resources; utilize catch net
for falling debris.
Operation
Proper design of discharge control
features; bridge runoff control/
collection system; protection of
roadside conveyance structures;
settling basins for roadway runoff
capture.
Operation
Proper design of discharge control
features; bridge runoff control/
collection system; protection of
roadside conveyance structures;
settling basins for roadway runoff
capture.
Construction

Consultation with Nevada and
Arizona SHPOs and Native
American Tribes for adverse effect
Cultural Resource Effects

Construction

Consultation with Nevada and
Arizona SHPOs and Native
American Tribes; PA with Advisory
Construction

Consultation with Nevada and
Arizona SHPOs and Native
American Tribes for adverse
SCO/CHAP-ES.WPD/003672772
ES-11
-------
EXECUTIVE SUMMARY
Table ES-3
Summary of Mitigation Measures9
Promontory Point Alternative Sugartoaf Mountain Alternative
Gold Strike Canyon Alternative
on National Historic Landmark
(NHL), related properties eligible for
National Register, and TCP.
Operation
Council, SHPOs, NPS,
Reclamation, WAPA, NDOT, ADOT,
and Native American Tribes for
adverse effect on NHL, related
properties eligible, for National
Register, and TCP; apply mitigation
measures developed through the
PA relating to bridge and corridor
design elements and TCP treatment
plan.
Operation
effects on National Register
properties related to Hoover Dam;
impacts on TCP would be severe,
and it is uncertain if any mitigation
would be acceptable to the tribes.
Consultation with SHPOs and tribes Apply measures developed through
for resolution of long-term effects, the PA to minimize long-term
effects.
Operation
Consultation with SHPOs and
tribes for resolution of long-term
effects.
Construction

PA with SHPOs, Advisory Council,
and other parties for adverse
effects on NHL and TCP; HAER
photo documentation of historic
dam views and features; consult
with Tribes for TCP mitigation;
coordinate access under bridge
construction for boat tours and
recreationists.
Operation

Provision for bicycle trail grade
separation for access to dam
crossing and connections to new
U.S. 93 crossing; form and color of
bridge structure compatible with
NHL and visual environment.
Land Use/Section 4(f) Effects

Construction

PA with SHPOs, Advisory Council,
NPS, Reclamation, WAPA, NDOT,
ADOT, and Native American Tribes
for measures to minimize harm to
NHL, related properties eligible for
National Register, and TCP;
coordinate construction access with
raft tours and recreationists.
Operation

PA with SHPOs, Advisory Council,
and other parties for adverse
effects on National Register
properties; impacts on TCP would
be severe, and it is uncertain if any
mitigation would be acceptable to
the tribes; coordinate access under
bridge construction for raft tours
and recreationists.
Operation

Provision for bicycle access to dam
crossing and connections to new
U.S. 93 crossing; form and color of
bridge structure compatible with
visual environment; consider
construction of noise barriers to
minimize impact on hikers in upper
canyon.
Construction

Implement public information
program; provide visual simulation
and project information.

Operation

Impacts could be lessened for the
bridge by coloring the concrete or
steel to blend with the
surroundings; use of colored
concrete on cable stayed and
suspension bridge would reduce
effect; use of desert varnish stain
on rock slopes.
Visual Resource Effects

Construction

Implement public information
program; provide visual simulation
and project information.

Operation

Use of colored concrete or steel on
bridge would reduce effect; use of
desert varnish stain on rock slopes;
set arch bridge deck height to retain
mountain view from dam, if feasible.
Construction

Implement public information
program; provide visual simulation
and project information.

Operation

Impacts would be reduced by
coloring the concrete or steel to
blend with the surroundings.
ES-12
SCO/CHAP-ES.WPD/003672772
-------
EXECUTIVE SUMMARY
Table ES-3
Summary of Mitigation Measures'
Promontory Point Alternative Sugarloaf Mountain Alternative Gold Strike Canyon Alternative
Construction
Properly post/restrict access to
construction areas; coordinate
construction activities with Lake
Mead Cruises; mark construction
zone in Lake Mead with buoys; use
netting to prevent debris from falling
into river/lake and to protect
recreationists.

Operation

Use unobtrusive, nonglare color for
bridge; no additional mitigation
required.
Recreation Resource Effects

Construction
Properly post/restrict access to
construction areas; coordinate
construction activities with Colorado
River raft and canoe launching
sites; use netting to prevent debris
from falling into river/lake and to
protect recreationists.
Operation

Use unobtrusive, nonglare color for
bridge; no additional mitigation
required.
Construction
Properly post/restrict access to
construction areas; coordinate
construction activities with
Colorado River raft and canoe
launching sites; use netting to
prevent debris from falling into
river/lake and to protect
recreationists; closure of hiking trail
is unmitigable.

Operation

Use unobtrusive, nonglare color for
bridge; consider installation of
noise barriers adjacent to hiking
trail.
Construction

No mitigation required.

Operation
No mitigation required.
Socioeconomic Effects

Construction

No mitigation required.

Operation

No mitigation required.
Construction

No mitigation required.

Operation

No mitigation required.
Construction

Investigate hazardous material use
and releases, and analyze soil
samples at Reclamation warehouse
storage yard; assess contractor
staging and disposal areas, and
conduct soil sampling if needed;
conduct sampling at dump pile and
remediate any contaminated soils,
also control runoff to site; conduct
soil sampling at abandoned
switchyard and remove/remediate
any PCB-contaminated soils, also
control runoff to site.
Operation
No mitigation required.
Hazardous Materials Effects

Construction

Investigate hazardous material use
and releases, and analyze soil
samples at Reclamation warehouse
storage yard; assess contractor
staging and disposal areas, and
conduct soil sampling if needed;
possibly conduct soil sampling at
the Arizona-Nevada Switchyard and
remove/remediate any PCB-
contaminated soils, also control
runoff to site; conduct soil and
sludge sampling at the Reclamation
sewage evaporation ponds, and
properly remove any contaminated
soils.
Operation
No mitigation required.
Construction

Control roadway runoff from
Nevada Spoil Pile through use of
barriers or diversion channels.
Operation
No mitigation required.
• No mitigation measures were identified for the No Build Alternative.
SCO/CHAP-ES.WPD/003672772
ES-13
-------
EXECUTIVE SUMMARY
This page intentionally left blank.
ES-14 • SCO/CHAP-ES.WPD/003672772
-------
CHAPTER l
Purpose and Need
1.1 Introduction

United States Highway 93 (U.S. 93) is the major commercial corridor for interstate
commerce among the states of Arizona, Nevada, and Utah. It is also a direct link between
Phoenix and Las Vegas, which are two of the fastest growing areas in the United States. It
carries a high volume of traffic from Interstate 40 to Las Vegas and Interstate 15 (1-15).
Approximately 30 miles southeast of Las Vegas, U.S. 93 crosses the Colorado River over
Hoover Dam. Traffic on Hoover Dam has become highly congested and hazardous
vehicle/pedestrian conflicts have increased as a result of large traffic volumes from both
private and commercial vehicles that use these routes from the south, southwest, and
southeast. The traffic volumes, combined with the mountainous terrain, hairpin curves,
inadequate sight distance, narrow dam crest roadway, and steep grades in the Hoover Dam
vicinity, create a major bottleneck with high accident potential and substantial delays.

The U.S. 93 corridor, in combination with other highways, creates a continuous north to
south corridor between Canada and Mexico, through the United States from Calgary,
Alberta, to Nogales, Sonora (Figure 1-1). These highways, consisting generally of four-lane
divided facilities with structural sections capable of supporting heavy vehicles, provide
north-south linkages from the international border with Mexico via Interstate 19 (1-19) from
Nogales to Tucson and Interstate 10 (1-10) from Tucson to Phoenix, in Arizona; and
Interstate 15 (1-15) in Nevada, Utah, Idaho, and Montana to the Canadian border. U.S. 93
provides a north-south link between 1-10 near Phoenix and 1-15 in the Las Vegas
metropolitan area. Much of U.S. 93, along with other roadway facilities in the corridor,
consists of two-lane undivided highway.

Currently the Nogales, Mexico, border crossing handles more than 250,000 truck crossings
annually and is the primary point of entry for produce shipped by truck into the United
States from Mexico (U.S. 93 Development Study, ADOT, 1993). The U.S. 93 corridor has been
recommended by the Arizona Department of Transportation (ADOT) to become Arizona's
link in the international trade route proposed by the North American Free Trade Agreement
(NAFTA). In addition to connecting Las Vegas and Phoenix, this corridor also links these
cities with Tucson and Salt Lake City, Utah.

ADOT plans to improve U.S. 93 to a four-lane divided facility from the Phoenix area to
north of Kingman, Arizona. In Nevada, U.S. 93 is a four-lane facility from Las Vegas to
Boulder City. The Nevada Department of Transportation (NDOT) is currently evaluating
transportation improvements in the Boulder City/U.S. 93 Corridor. After implementing
ADOT and NDOT improvements, the only section of U.S. 93 between Phoenix and Las
Vegas to remain a two-lane facility will be the 19-mile segment that includes Hoover Dam.
While most of the corridor would consist of a high-speed divided facility, the segment in
the Hoover Dam vicinity creates a traffic bottleneck between Nevada and Arizona,
potentially interfering with interstate and international commerce.

Hoover Dam is the only Colorado River crossing near Las Vegas. The closest alternate
crossings are at Davis Dam, 67 miles downstream or at Laughlin, Nevada, 70 miles
downstream (Figure 1-2). Because shorter travel times and distances reduce accident
exposure and transit costs, the shorter Hoover Dam crossing is preferred by the commercial
trucking industry for travel in the Las Vegas-to-Phoenix corridor.

SCO/CHAP-1 .WPD/003672773 1-1
-------
CHAPTER 1 PURPOSE AND NEED
Alternatives to crossing the Colorado River at Hoover Dam are United States Highway 95
(U.S. 95) and State Route 163 (SR163) in Nevada to Arizona State Route 68 (SR 68)
(Figure 1-2), which would add 23 miles to the trip from Las Vegas to Kingman. Another
route from Las Vegas to Kingman—U.S. 95 to Interstate 40 to Needles, California, and then
east to Kingman—adds 70 miles to the trip.

If the existing bottleneck is eliminated at the dam, U.S. 93 across the Colorado River would
be the shortest and fastest route for through traffic between Arizona and Nevada. Traffic
flow is generally at speeds near posted limits except at the roadway approaches to Hoover
Dam. Average speeds recorded on dam approaches and across the dam crest were as low
as 8 miles per hour (mph) (Traffic Study: Colorado River Bridge, December 1991).
1.2 History
Hoover Dam, dedicated in 1935, is approximately 9 miles east of Boulder City and 80 miles
northwest of Kingman (Figure 1-2). The dam is 1,244 feet long and is situated in the Black
Canyon of the Colorado River at the southeastern border of Nevada and the northwestern
border of Arizona.

In 1955, the American Society of Civil Engineers named Hoover Dam one of America's
seven modern civil engineering wonders. In 1985, it was designated by the U.S.
Department of the Interior (DOI) as a National Historic Landmark (NHL) and by the
American Society of Civil Engineers as a National Historic Civil Engineering Landmark.

Hoover Dam is key to controlling and regulating the lower Colorado River. It controls
floods; stores water for irrigation, municipal, and industrial uses; and provides
hydroelectric power generation, recreation opportunities, and wildlife habitat. Except for
the tourist facilities, the area surrounding Hoover Dam (known as the Hoover Dam
Reservation) is designated as a security-restricted area and is not accessible to the public.

The original road from Boulder City to Hoover Dam was built to provide access for dam
construction. From 1934 until the early 1940s, vehicular traffic to the dam came primarily
from Las Vegas and Boulder City on U.S. 93. Because few vehicles crossed the dam at that
time, there was no interference with dam operations and no traffic safety hazards for dam
visitors.

Originally, the highway from Kingman to the dam was a lightly traveled primitive dirt
road. Since the early 1940s, ADOT has been improving U.S. 93 between the dam and
Kingman, the shortest travel route between Arizona and Nevada. As a result of these
highway improvements and the shorter travel distances between Kingman and Las Vegas,
through traffic over the dam has steadily increased. This increase, together with population
growth in southern Nevada and increasing tourist traffic to Las Vegas, has resulted in
serious traffic congestion on U.S. 93 on and near the dam.

As early as 1965, Reclamation recognized the U.S. 93 problems, including sharp turns;
narrow roadways; inadequate shoulders; poor sight distances; low travel speeds; and the
associated potential for loss of life, contamination of Lake Mead and the Colorado River
from hazardous material spills, and effects to Hoover Dam because of these roadway
deficiencies.
1 -2 SCO/CHAP-1 .WPD/003672773
-------
CALGARY
SEATTLE,
PORTLAND
VEGAS

HOOVER DAM

ARIZONA
NEW MEXICO

CRUCES
LOS ANGELES'
NOT TO SCALE
LEGEND
U.S. 93

INTERSTATE SYSTEM
FIGURE 1-1

U.S. 93 TRANSPORTATION CORRIDOR
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
142B83.12.PM 2439.18 Itti/SS
-------
CHAPTER 1 PURPOSE AND NEED
This page intentionally left blank.
SCO/CHAP-1.WPD/003672773
-------
NOT TO SCALE
LEGEND

—— • STATE BOUNDARY

——— HIGHWAYS
FIGURE 1-2
EXISTING ALTERNATE ROUTES TO

U.S. 93 AND HOOVER DAM CROSSING
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
1A9RA3 19 PM 7439 13
-------
CHAPTER 1 PURPOSE AND NEED
This page intentionally left blank.
1 -6 SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Reclamation took the lead in seeking a solution to the roadway problems at Hoover Dam.
They conducted the following studies: an origin and destination analysis in 1966, a
preliminary U.S. 93 relocation corridor study in 1990, and a detailed alignment and bridge
type selection study for three bypass alternatives in 1992 (see Chapter 2, Alternatives).

In 1989, Reclamation created the "Colorado River Bridge Project Management Team"
(PMT), which directed engineering and environmental studies, developed funding
agreements, and managed the preliminary design of a new crossing. The PMT was made
up of Reclamation, ADOT, NDOT, Federal Highway Administration (FHWA), and the
National Park Service (NFS).

Before releasing the Draft Environmental Impact Statement (DEIS) for public review in
1993, Reclamation withdrew from the project as the lead agency because their mission
emphasis changed from constructing major public works projects to water resource
management. With no lead agency or funding to continue the environmental process for a
new crossing, the project was officially put on hold in 1995.

In the spring of 1997, governors and Congressional representatives from Nevada and
Arizona appealed to the U.S. Secretary of Transportation to help fund the completion of the
environmental studies. A federal appropriation provided funds to resume studies to
evaluate removing truck traffic from Hoover Dam. ADOT and NDOT agreed to contribute
funds to complete the studies. In May 1997, the FHWA, Central Federal Lands Highway
Division (CFLHD), was named lead agency to resume the Hoover Dam Bypass Project—the
project being evaluated in this Environmental Impact Statement (EIS).

1.3 Previous Studies Conducted

As discussed above, U.S. 93 deficiencies in the Hoover Dam vicinity were identified as long
ago as 1965. Recognition of these roadway deficiencies resulted in a series of studies that
evaluated alternative methods to alleviate deficiencies. Table 1-1 lists the studies conducted
to date and provides a brief description of study purposes and findings.

Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared Summary of Study
U.S. 93- 466 Hoover Dam Origin and Destination Study determined the characteristics of traffic
Study, prepared by State of Nevada Department of congestion at Hoover Dam. Determined that traffic
Highways and U.S. Department of Commerce, Bureau near Hoover Dam can be divided into two
of Public Roads, November 1968. categories: through traffic (defined as vehicles
using the dam as a bridge to complete their trip),
and Hoover Dam dead-end trips (defined as
vehicles whose destination is Hoover Dam).
Suggested four methods to alleviate traffic
problems: (1) develop more parking areas and
modify the dam to add two traffic lanes; (2)
construct an upstream crossing; (3) construct a
downstream crossing; and (4) construct a
downstream crossing near Willow Beach (not
considered economically justified in 1966 because
of Davis Dam crossing downstream).
SCO/CHAP-1 .WPD/003672773
1 '7
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
A Study and Recommendations for Handling Traffic
and Conducting Visitors at Hoover Dam, prepared by
Perkins & Will Corporation for Reclamation, April
1971.
Resume of Studies on Colorado River Crossing Below
Hoover Dam, prepared by Reclamation, January 1972.

Facilitating Traffic Flow, Alleviating Safety Hazards,
and Expediting Access - Hoover Dam, prepared by
Reclamation, September 1977.
1983 Analysis of Colorado River Crossing Below
Hoover Dam, prepared by Reclamation, June 1983.
Black Canyon Bridge, Colorado River Crossing,
Hoover Dam, prepared by Reclamation, January 1986.
Preliminary Geologic Report for Colorado River Bridge
Crossing, Nevada Approach, Clark County, Nevada,
prepared by Reclamation, March 1988.
Study determined methods and facilities to handle
vehicle traffic and conduct visitors on dam tour.
Study assumed that through traffic would bypass
the dam by relocating U.S. 93 to a new downstream
bridge and that all other traffic would continue to
travel across the dam. Recommended a highway
bypass, parking structures, and minor highway
improvements.

Study requested Congressional authorization to
construct an alternative Colorado River crossing
near Hoover Dam.

Study requested Congressional authorization to
increase the cost ceiling of the Boulder Canyon
Project Act (authorized in 1928). Additional funds
would have provided new facilities to improve traffic
flow, alleviated safety hazards, and provided a safe
experience for Hoover Dam visitors.

Study described the project; explored potential
hazards to the dam; updated traffic, visitor use, and
construction cost data; recommended a portion of
construction costs for a bridge be allocated to
power revenues; and concluded that a bridge is
needed to bypass the dam to provide safe
conveyance of traffic on U.S. 93 for safe, efficient
operation of Hoover Dam.

Study described the project; provided a basis for
seeking funding; explored potential dam hazards;
updated traffic, visitor use, and construction cost
data; and concluded that a bridge crossing could
eliminate some future potential costs to government
facilities at Hoover Dam by eliminating commercial
vehicles from using the dam crest.

Contains text, photos,-and geologic plan maps at a
scale of 1 inch equals 200 feet of the Nevada side
approach of the Gold Strike Canyon alignment.
Colorado River Bridge - Hoover Dam, Phase A Route
Study, prepared by Reclamation, October 1990.
Study determined the preferred general corridor to
relocate U.S. 93 crossing the Colorado River. The
study considered nine routes. A January 14,1991,
memorandum recommended that six of the routes
be eliminated because of increased environmental
impacts, disturbance of large amounts of currently
undisturbed NPS lands, and increased costs.
Routes recommended for further study included
Promontory Point, Sugarioaf Mountain, and Gold
Strike Canyon.
1-8
SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
Reconnaissance Geologic Investigation Highway
Relocation, prepared by Reclamation, November 5,
1991.
Traffic Study. Colorado River Bridge - Hoover Dam,
prepared by CH2M HILL for Reclamation, December
1991.
Colorado River Bridge Crossing Phase B Corridor
Study Developed Bridge Alternatives, prepared by
Parsons, Brinkerhoff, Quade & Douglas and HDR
Engineering for ADOT and NDOT, January 1992.
Movements and Habitat Use of Desert Bighorn in the
Black Canyon Area, Arizona Game and Fish
Department for Reclamation, March 1992.
Colorado River Bridge-Hoover Dam: Public Involvement Plan,
prepared by CH2M HILL for Reclamation, May 15,1992.
Presence and Movements of Peregrine Falcons in the Area of the
Proposed Black Canyon Bridge Project, prepared by Arizona
Game and Fish Department for Reclamation and NPS, June 1992.
Provided the designers with geologic data
including photos and rough geologic mapping for
the Phase B Report. Geologic features are
approximate as no stationing or surveying had
been done along the proposed alignments.

This traffic study analyzed U.S. 93 from the Gold
Strike Casino (now the Hacienda Hotel) to the
Arizona lookout south of the dam. Its purposes
were to perform a Traffic Systems Management
(TSM) study and to provide support to the
Reclamation Phase B Corridor Study and EIS for
the Colorado River Bridge project. Findings
included the existing level of service to be LOS D;
through trips represented 70 percent of the total
traffic across the dam; average travel time from the
Arizona lookout to the Nevada park-n-ride was
between 8 minutes (off peak) and 13 minutes
(during peak hours); and 30 percent of accidents on
the dam involved semitrailer trucks.

Reclamation conducted the Phase B Corridor
Studies in conjunction with preparation of the
project EIS. The studies identified initial bridge
concepts, preliminary design parameters, and
costs. This final phase of the bridge type studies
began in August 1991 and developed the selected
bridge alternatives and their estimated costs.

The study involved collaring and 2-year monitoring
of 49 desert bighorn in the Black Mountains
adjacent to Hoover Dam to determine areas of
importance, movement corridors, habitat use, and
reactions to U.S. 93. Three separate ewe
groups/areas were found with significantly different
habitat use and home range size. All three of the
build alternatives were found to bisect one or more
of the ewe groups' home range. The Gold Strike
alignment presented the greatest potential
difficulties for bighorn.

The goals of the plan are to: (1) identify issues of concern to the
community; (2) provide a plan to address community concerns;
and (3) inform the public about the NEPA procedures for
selecting a preferred alternative. Formulation of the plan
involved in-depth interviews with residents, community and civic
leaders, business people, public officials, and members of
environmental organizations.

The purpose of the study was to assess impacts of
proposed bridge and associated construction action
on the peregrine falcon. Specific objectives of this
study were: 1) to locate peregrine falcon breeding
areas, 2) to identify important foraging habitats
along the river corridor, and 3) to document
SCO/CHAP-1 .WPD/003672773
1-9
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
Traffic and Revenue Study for Colorado River
Crossing, prepared by CH2M HILL and Price
Waterhouse for Reclamation, August 1992.
Colorado River Bridge - Hoover Dam, Phase B
Corridor Studies, prepared by Bureau of Reclamation,
August 1992.

(Note: This includes the "Developed Bridge
Alternatives" report listed above.)
presence/ absence of peregrines during the
nonbreeding season. The area covered in this
study was Lake Mead from Fortification Hill to
Hoover Dam, and the Black Canyon of the Colorado
River from Hoover Dam downstream to Windy
Cove. The report recommendations were:
1) continue to monitor all Black Canyon peregrines
discovered during this study from 1992 through a
minimum of at least 3 years after completion of the
roadway and bridge, and 2) in the event that the
preferred bridge corridor is possibly within
2 kilometers (km) of an active peregrine eyrie,
monitor impacts of the construction.

The purpose of the study was to support the new
crossing EIS and prepare financial feasibility data to
determine the maximum amount of revenue
obtainable if the crossing were a toll facility. The
study area included U.S. 93 from the U.S. 95
junction to the junction of Arizona Route 68; Arizona
68 west to the Colorado River; Nevada 163 west to
U.S. 95; and U.S. 95 north to the junction with
U.S. 93. It was concluded that the only feasible
alternative route, the Colorado River crossing at
Laughlin-Bullhead City, is sufficiently distant to
discourage most traffic from diverting around the
proposed toll bridge.

Studies assessed Promontory Point, Sugarloaf
Mountain, and Gold Strike Canyon alternatives.
Included were a highway approach study and a
bridge type study. Identified physical factors that
would affect the design, cost estimates, or
schedules; developed preliminary mitigation
features; included preliminary designs; included a
construction cost estimate; and included a final
design schedule and construction schedule.
1-10
SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
Guttural Resource Report: Colorado Bridge
Crossing/Hoover Darn Project Bridge Crossing and
Highway Alignment Survey, prepared by Reclamation,
1992.
Arizona and Nevada Site Forms for Colorado Bridge
Crossing/Hoover Dam Project Bridge Crossing and
Highway Alignment Survey, prepared by Reclamation,
1992.
Hoover Dam Bridge Crossing Cultural Resource Site
Reassessment; Nevada Sites 26CK4698,26CK4739,
26CK47SO, 26CK47S1, 26CK4752, and26CK4763,
prepared by Reclamation, 1993.
This study reports the results of a 145-acre cultural
resource survey of the proposed bridge crossing
locations and highway corridors. Forty-four features
were identified within the area of potential effect.
Eight features had been identified in previous
cultural resource activities. The remaining 36 sites
were identified during cultural resource surveys for
this project. One feature, Hoover Dam, is listed on
the National Register of Historic Places (NRHP) and
is also a National Historic Landmark (NHL). Two
features, the Old Government Railroad and the Old
Boulder City Water System, have been determined
eligible for listing in the NRHP. Most of the
remaining features are associated with the
construction, operation, or maintenance of Hoover
Dam. These features are not individually eligible
but may contribute to the NHL or a historic district
focused on the dam. Reclamation determined that
a World War II anti-aircraft bunker located on the
Arizona side of the river is individually eligible for
the NRHP. This study also determined that all
alignment options would affect the historic and
visual setting of Hoover Dam.

This volume was prepared as a stand-alone
supplement to the report prepared by Reclamation.
It includes site forms for all the cultural resource
features investigated by Reclamation in connection
with the survey.

Reclamation determined that 23 of the 29 Nevada
cultural resource sites originally identified were
eligible for NRHP listing as contributing elements to
a potential, undefined historic district associated
with the construction and/or operation and
maintenance of Hoover Dam. The remaining six
sites were determined not eligible. The Nevada
SHPO questioned Reclamation's determinations
and asked for additional information and
clarification. This report documents a survey to
relocate and reassess the six sites which the SHPO
expressed concern about. Reclamation determined
that except for portions of the railroad grade
(26CK4751), none of the reassessed cultural
resource sites would be affected by any of the
Hoover Dam bridge crossing alternative alignments.
SCO/CHAP-1 .WPD/003672773
1-11
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
Hoover Dam Bridge Crossing Cultural Resource Site
Reassessment Arizona Sites DD;14:15, DD:14:16,
DD:14:17, and DD: 14:19, prepared by Reclamation,
1993.
Desert Bighorn Movements and Habitat Use in
Relation to the Proposed Black Canyon Bridge
Project: Nevada, Cooperative National Park
Resources Studies Unit, University of Nevada for
Reclamation, May 1993.
U.S. 93 Colorado River Crossing Corridor Study,
prepared by Parsons Brinkerhoff Quade & Douglas for
NDOT, December 1994.
Biological Assessment for the Hoover Dam Bypass
Project, prepared by CH2M HILL for Federal Highway
Administration, Central Federal Lands Highway
Division, February 1999.
U.S. 93 Hoover Dam Bypass Project, Sugarloaf
Mountain Alternative, Historic Resources Survey,
prepared by Kurt P. Schweigert, Associated Cultural
Resource Experts for Federal Highway Administration,
Central Federal Lands Highway Division, and
CH2M HILL, August 1999.
Reclamation determined that four of the eight
Arizona cultural resource sites originally identified
were NRHP eligible as contributing elements to a
potential, undefined historic district associated with
the construction and/or operation and maintenance
of Hoover Dam. The remaining four were not
eligible. The Arizona SHPO questioned
Reclamation's determinations and asked for
additional information. This report documents a
survey to relocate and reassess the four sites which
the SHPO expressed concerns about. Reclamation
determined that none of the reassessed cultural
resource sites would be affected by any of the
Hoover Dam bridge crossing alternative alignments.

This study characterized bighorn sheep habitat
quality and information on movements of radio-
collared bighorn to estimate home range size and
patterns of movement. Total home range size was
determined. It was found that bighorn sheep
heavily use the area of the proposed alignments on
a year round (ewes) and seasonal basis (rams in
fall). The Sugarloaf Mountain Alternative was found
to intrude the least on high-use areas and that
habitat loss will be greatest for the Gold Strike
Canyon Alternative. Big game fencing is
recommended along the new highway to reduce
bighorn sheep/motor vehicle collisions.

A continuation of Reclamation studies, this report
analyzed two longer alternatives: Willow Beach
South (26 miles) and Hoover Dam/Boulder City
Bypass (31 miles). Study purpose was to
determine the relative feasibility of these corridors.
Feasibility was determined by relative cost,
technical engineering difficulty, major impacts, and
user benefits.

Determined that the preferred alternative may affect
the desert tortoise but will not affect any of the other
listed species in the project area. Impacts to the
desert tortoise would be avoided or minimized with
conservation measures.

This survey recorded 14 historic features within the
area of potential effects (APE) of the preferred
alternative, including the Hoover Dam National
Historic Landmark. The report evaluated the 13
other historic features for eligibility to the National
Register of Historic Places as elements relating/
contributing to the construction and operation of the
Hoover Dam. The report also analyzed the affect of
the preferred alternative on these historic sites.
1-12
SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared
Summary of Study
U.S. 93 Hoover Dam Bypass Project Archaeological
Resources Survey Report, prepared by CH2M HILL for
Federal Highway Administration, Central Federal
Lands Highway Division, April 2000.
Hoover Dam Bypass Bridge Financial Feasibility
Study, prepared by Hagler Ballly Services, Inc. for
Arizona Department of Transportation and Nevada
Department of Transportation, June 2000.
Ha'tata (The Backbone of the River): American Indian
Ethnographic Studies Regarding the Hoover Dam
Bypass Project, prepared by Richard W. Stoffle et al.,
University of Arizona for Federal Highway
Administration, Central Federal Lands Highway
Division, and CH2M HILL, October 2000a.
Hoover Dam Bypass Project Ethnohistoric Overview
and Assessment, prepared by David S. Whitley and
Peter Nabokov, W&S Consultants, for Federal
Highway Administration, Central Federal Lands
Highway. Division, and CH2M HILL, October 2000b.
This report documents the results of a Class III
(intensive) archaeological survey of the three
alternative alignments of the proposed bypass. It
documents a field survey conducted for all
alignments in March 1998 and an intensive
archaeological site mapping and recording
investigation on two sites hi June 1999. The survey
and mapping recorded a total of five prehistoric
archaeological sites, all located in Arizona, within
the APE of the Promontory Point and Sugartoaf
Mountain Alternatives. The report concluded that
none of the five sites had sufficient research value
for prehistoric archaeology, and all were thus found
ineligible for the National Register.

This study outlines options available to meet the
financial demands of constructing the Hoover Dam
Bypass Project, to aid policymakers in their
selection of alternate strategies. The study analyzed
the following funding options: federal funding,
existing state program funding, new state funding
sources (statewide taxes, transportation taxes and
fees, tourism-related taxes and fees, and
value-capture programs), and tolls or other user
charges.

This study recorded and evaluated the results of
field visits conducted by University of Arizona
anthropologists with Native American tribal elders.
Interviews were conducted in May/June 1998 and
May 2000 with representatives from 13 tribes. The
report documents feelings of the tribal
representatives about the cultural values of the
lands in the project area, tribal concerns about the
impact of the bypass project, and tribal
recommendations for minimizing the impacts.

Examined ethnohistoric data from archaeological,
historical, and ethnographic sources from the
general region of the Hoover Dam Bypass Project
study area. Identified traditional Native American
land use practices, values, and beliefs. It provided a
context for the contemporary ethnographic (FHWA,
October 2000) and archaeological (FHWA,
April 2000) studies conducted for the project, with
the goal of aiding the determination of whether
National Register-eligible traditional cultural
properties (TCPs) are present in the project area.
SCO/CHAP-1 .WPD/003672773
1-13
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-1
Previous U.S. Highway 93 and Hoover Dam Studies
Study Name, Author, and Date Prepared Summary of Study

The Land Still Speaks: Traditional Cultural Property Summarized and evaluated the findings from the
Eligibility Statement, prepared by University of Arizona ethnographic (FHWA, October 2000a) and
and the American Indian Core Consultation Work ethnohistoric (FHWA, October 2000b) studies
Group for Federal Highway Administration, Central conducted for the project This report identified the
Federal Lands Highway Division, October 2000c. Gold Strike Canyon and Sugarioaf Mountain TCP,
and determined it to be eligible for the National
Register of Historic Places.

1.4 Need for the Project

Several deficiencies on U.S. 93 from the Gold Strike Inn (recently rebuilt as the Hacienda
Hotel), Nevada, to Milepost 1 (MP1) in Arizona have been identified, both from a highway
operational standpoint and from a dam operational standpoint. These deficiencies not only
create travel delays, but also contribute to accidents and vehicle conflicts.

1.4.1 Highway Deficiencies

The U.S. 93 roadway approaches to Hoover Dam include numerous substandard geometric
elements. These elements include horizontal curves with radii too short to provide
adequate turning room and that are bounded by rock walls that limit sight distance along
the road. The existing roadway cross section does not provide adequate width for disabled
vehicles or passage by emergency vehicles; and, at several locations, the roadway width is
not adequate for turning.

The highway speed limit is reduced from 55 to 15 mph before the dam from each direction.
The primary reasons for the speed reduction are the numerous hairpin curves required for
the highway to reach the dam crest roadway and the steep grade. Three curves are of
particular concern: one on the Nevada side, referred to as the Nevada Hairpin Curve; and
the other two on the Arizona side, referred to as the Arizona Hairpin Curve and the
Arizona Horseshoe Curve (see Figure 2-3).

Each of these curves provides less than a 20-mph design speed, and each is located less than
1 mile from the dam. The extreme hairpin curves do not allow adequate width for
commercial trucks to pass in opposite directions. Trucks meeting at these locations usually
must come to a complete stop, and one truck often must back up to allow the other room to
negotiate the curve. The overall impact of these highway deficiencies on the traffic level of
service at the dam is discussed in Section 1.4.2 below.

1.4.2 Inadequate Roadway Capacity

The Hoover Dam section of U.S. 93 has reached its capacity during peak periods and cannot
provide additional capacity with the current roadway alignment. In 1991, average travel
speeds of the 2 miles of roadway on either side of Hoover Dam were 8 to 18 mph. The crest
road at Hoover Dam has reached its maximum traffic-carrying capacity and has been at that
level since at least 1991. Table 1-2 compares 1997 traffic on the dam with that projected for
the years 2017 and 2027.
1-14 SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-2
Traffic Volumes and Level of Service at Hoover Dam
1997 2017 2027
Traffic Volumes (Average Annual T 1,500 21,100 26,000
Daily Traffic)8
Level of Service F_ F __F
8 Actual Reclamation 2000 traffic counts indicate a somewhat greater growth rate than that used for these
projections.
Source: Appendix A, Traffic Analysis.

The method used to describe and determine capacity and traffic operating conditions in this
study is outlined in the Highway Research Board's Highway Capacity Manual - Special
Report 209 (3rd Edition, 1994), which expresses levels of service (LOS). The LOS concept is a
qualitative measure to describe traffic operational conditions and motorist perceptions; it
describes speed, convenience, and safety. Six LOSs are used to define operating conditions,
designated by the letters A through F. LOS A represents the best operating conditions,
while LOS F represents heavily congested flow with traffic demand exceeding highway
capacity (Figure 1-3).

Considering the existing highway configuration, speed limit, pedestrians, and vehicle mix
(passenger vehicles, semitrucks, and recreational vehicles) of through traffic, highway
capacity is 1,200 vehicles per hour. This calculation is based on average operating speeds
between 15 and 20 mph and does not consider peak periods such as weekends, holidays, or
special events that further exacerbate traffic conditions. The 1991 peak volume of
1,168 vehicles per hour was 97 percent of highway capacity, resulting in traffic congestion
(traffic count, August 8,1991). Traffic counts taken in 1996 indicated peak volumes at or
exceeding the total highway capacity. Traffic congestion is increased when vehicles have
mechanical difficulties because the shoulders are too narrow to pull off the road.

Primary factors that limit capacity through this section of U.S. 93 are tight curves and steep
grades associated with the approach roadways on both sides of the dam; and a single lane
in each direction. On the dam crest, conditions are degraded by numerous conflicts with
pedestrians crossing the roadway. Neither the improvement of these geometric constraints
nor widening of the corridor is feasible with the current alignment over the dam.

1.4.3 Travel Times

Based on current posted speeds along U.S. 93 from the Hacienda Hotel, Nevada, to MP 3 in
Arizona (6.3 miles), the estimated average travel time for the existing alignment is
16.5 minutes. A bypass roadway could be estimated to operate at 55 mph. The Sugarloaf
Mountain and Gold Strike Alternatives would reduce the distance to 5.5 miles, resulting in
a travel time of 6 minutes. This estimate represents a 10.5-minute reduction for each
through-vehicle. The Promontory Point Alternative would reduce the distance to 6.1 miles,
with a time savings of approximately 10 minutes.

Based on projections that 26,000 vehicles will cross the dam in the year 2027, the peak-hour
traffic volume is estimated at 2,340 vehicles. This projection indicates that more than
1,170 hours of travel time delay during the 3 peak hours could be eliminated (see
Appendix A, Traffic Analysis).

SCO/CHAP-1.WPD/003672773 1-15
-------
CHAPTER 1 PURPOSE AND NEED
1.4.4 Interference in Dam Operation

The high volume of vehicles crossing the dam interferes with the vehicle movements
needed for operating and maintaining the dam and its facilities.

Vehicular traffic affects most highway and dam maintenance activities. These activities
include repairing and replacing turbines and generators, replacing lights along the highway
on the dam, maintaining the highway approaches, repairing the spillway, and using the
overhead cable that transports heavy equipment and material to the power house. The
traffic interference results in additional time and higher costs to complete these activities.

1.4.5 Accident Rate and Potential for Pedestrian-Vehicular Accidents on Hoover
Dam
*
The number of tourists to the Lake Mead National Recreation Area (LMNRA) and Hoover
Dam is increasing. Visitors taking the guided tour at the dam have more than tripled
(300,000 per year in 1937 to 1.03 million in 1997). This increase is partially due to the
opening of the new Hoover Dam Visitor Center in 1996. In addition to pedestrian traffic,
about 11300 vehicles per day cross Hoover Dam; this volume is projected to be about
26,000 vehicles daily in the year 2027.

Since 1964, more than 500 accidents have occurred between Nevada MP 2.2 and Arizona
MP 1.2 (a 3.4-mile stretch of highway including the dam). Forty-three accidents between
1985 and 1991 involved one or more personal injuries, including two fatalities. Commercial
trucks were involved in 96 of the accidents. In every accident, the cause was partially
attributable to existing highway conditions, such as sharp curves, narrow highway width,
insufficient shoulder width, poor sight distances, and slow travel speeds. Accident causes
that are aggravated by the existing U.S. 93 configuration can be classified as either
mechanical failure (engine problems, tire blowouts, or brake failure) or human error
resulting from fatigue, intoxication, or judgment errors. As the average annual daily traffic
(AADT) across the dam continues to increase, the number of accidents continues to
increase accordingly.

Detailed accident data were obtained from both NDOT and ADOT for the years 1994
through 1997 (Table 1-3). The following data are for the section of U.S. 93 from the
Hacienda Hotel in Nevada to MP 3 in Arizona.
Table 1-3
Accident Data for 1994 to 1997
Accident Type
Total
Arizona
Nevada
Total
45
131
Percent of Total
Opposing Direction
Rear-end
Sideswipe
Hit Fixed Object
Overtumed/Off-Road
Other
11
7
5
5
7
10
34
21
9
3
6
13
45
28
14
8
13
23
34
21
11
6
10
18
100
1-16
SCO/CHAP-1 .WPD/003672773
-------
Level of Service A.
Level of Service D.
Level of Service B.
Level of Service E.
Level of Service C.
Level of Service F.
SCX3142883.12.03 level pm 996
FIGURE 1-3
LEVEL OF SERVICE CLASSIFICATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
1-17
-------
CHAPTER 1 PURPOSE AND NEED
This page intentionally left blank.
1-18 SCO/CHAP-1.WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
Table 1-3 shows a high percentage of multiple-vehicle accident types (opposing direction,
rear end, and sideswipes) indicating heavy congestion in the study area. The accident rate
along this 6.38-mile section of U.S. 93 is 1.35 per million vehicle miles traveled. This rate is
slightly higher than the Nevada average of 1.15 accidents per million vehicle miles traveled.
Analysis of the same data for the U.S. 93 within 1 mile of Hoover Dam shows a much
higher accident rate than the 3-mile approaches. The 0.5-mile segments of U.S. 93
approaching Hoover Dam have an accident rate of 3.97 per million vehicle miles traveled.
This rate is over three times the Nevada average of 1.15 per million vehicle miles traveled
for rural principal arterials. Similar to the conclusion that can be drawn from the types of
accidents, this high rate near Hoover Dam also indicates high levels of congestion.

1.4.6 Safeguarding Hoover Dam Power Plant, Lake Mead, and Colorado River
from Hazardous Spills or Explosions

Hoover Dam is a major power supplier for Southern California industry (generating about
4 billion kilowatt-hours of electricity annually); and Lake Mead is an essential storage
facility for the water supply for Southwest industries, municipalities, and farmlands.

Many vehicles currently crossing the dam carry volatile fuels, chemicals, or hazardous
materials (including explosives, flammable fuels, radioactive materials, acids, and caustic
chemicals). Potential hazards resulting from these materials include ignition of combustible
materials, contamination of Lake Mead or the Colorado River, and damage to the power
house and associated equipment if the materials entered the dam power plant and outlet
works. A reasonable worst-case scenario would be the release of gasoline (the flammable
liquid most commonly transported across the dam), followed by delayed ignition, resulting
in loss of life, severe injuries, and long-term interruption of power generation.

Of particular concern is the highway drainage system in the area near the dam on the
Nevada side of the river. Currently, the drainage flows off the edge of the road, down the
canyon face, onto the Nevada power house roof, and into the Colorado River. In addition
to potential water pollution issues, materials spilled onto the road would drain off the road
onto the Nevada power house, possibly resulting in power house damage or destruction.
The proposed project may not specifically remedy these conditions, but will remove
vehicles transporting large volumes of hazardous materials from the dam crest and provide
them a straight, four-lane highway crossing, which will result in a corresponding reduction
in potential spill risks.

1.4.7 Quality of Visitors' Experiences at Hoover Dam

There were 9.7 million visitors to the LMNRA in 1997 (personal communication, Bill Burke
of the NFS, 1998). Hoover Dam is a popular national and international tourist destination.
Tourists enter the visitor center, take the tour, patronize the snack bar, and walk across the
dam crest to photograph the facilities from various upstream and downstream vantage
points. These activities contribute to traffic congestion and can result in vehicle and
pedestrian conflicts. Through-vehicle and truck traffic also emit noise and vehicle exhaust,
which diminishes the visitors' experiences at the dam.

1.5 Purpose of Project

The purpose of the project is to reduce or eliminate through traffic over Hoover Dam to
accomplish the following objectives:

SCO/CHAP-1.WPD/003672773 1-19
-------
CHAPTER 1 PURPOSE AND NEED
• Minimize the potential for pedestrian-vehicle accidents on the dam crest and on the
Nevada and Arizona approaches to the dam

• Remove a major bottleneck to interstate and international commerce and travel in the
west by reducing traffic congestion and accidents in this segment of the major
commercial route between Phoenix and Las Vegas

• Reduce travel time in the dam vicinity

• Protect Hoover Dam employees, visitors, equipment, power generation capabilities, and
Colorado River waters while enhancing the visitors' experience at Hoover Dam by:

- Safeguarding dam and power plant facilities and the waters of Lake Mead and the
Colorado River from hazardous spills or explosions

- Protecting the dam and power plant facilities from interruptions in electricity and
water delivery

- Providing improved conditions for operating and maintaining Hoover Dam
facilities

1.6 Relationship of the Proposed Project to the Statewide Plan

or Urban Transportation Plan

This section describes travel demand in relation to the Nevada and Arizona plans and
pertinent legislation.

1.6.1 Nevada

The NDOT's Statewide Transportation Improvement Program (STIP) was developed
through coordinated efforts of the NDOT; federal, state, local, and tribal governments; and
with agencies, planning organizations, transportation providers, and the general public
(NDOT, 1997). Evaluating a Hoover Dam bypass is included in the STEP (1998).
Constructing a bypass at Hoover Dam is one of six projects listed in NDOT's billion dollar
Highway Superproject Program and is shown in NDOT's Work Program—Long Range
Element (1998 through 2007).

1.6.2 Boulder City/U.S. 93 Corridor

NDOT, in cooperation with FHWA, began the Boulder City/U.S. 93 Corridor Study and EIS
in November 1999. The proposed project involves traffic improvements to U.S. 93 in the
Boulder City area, referred to as the U.S. 93 Corridor. The EIS will study the corridor
between a western boundary on U.S. 93 in Henderson, Nevada, approximately 1 mile north
of the Railroad Pass Hotel Casino, and an eastern boundary on U.S. 93 approximately 4.7
miles east of downtown Boulder City. The eastern boundary is coincident with the planned
western end point of the Hoover Dam Bypass project. The project covers a total distance of
approximately 10.4 miles on the present route of U.S. 93. The purpose of the project includes
reducing traffic congestion and accidents in the corridor, accommodating current and
1-20 SCO/CHAP-1.WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
projected traffic demand, and improving system linkage and route continuity on U.S. 93 for
interstate commerce. The planned completion date for the EIS process is June 2002.

NDOT is pursuing development of Boulder City /U.S. 93 Corridor improvements primarily
to reduce traffic congestion and accidents in the corridor (see Chapter 2, Alternatives).
Previously, NDOT evaluated the feasibility of two alternative Colorado River crossings
associated with a bypass (NDOT, 1994). The options were the Willow Beach South Crossing
and the Hoover Dam/Boulder City Bypass. To ensure uniformity in the analyses and to
provide a more meaningful comparison between the two routes, it was assumed that the
two alternatives had the same starting and ending points, and the longer of the two routes
(Willow Beach) was used to establish the termini. The western terminus was located at
Railroad Pass west of Boulder City near the U.S. 93/U.S. 95 interchange in Nevada. In
Arizona, the eastern terminus was approximately 1 mile south of the LMNRA boundary
where the existing road narrows from a four-lane divided facility to two lanes before
reaching Hoover Dam along U.S. 93.

The Boulder City/U.S. 93 Corridor improvements and the Hoover Dam Bypass are separate
projects with independent utilities conceived to meet separate needs; each could be
constructed without the other, and each would still fulfill its own objectives. The Boulder
City Corridor improvement objective is to reduce traffic congestion and accidents in
Boulder City and on U.S. 93; constructing a Hoover Dam Bypass will not reduce or
eliminate traffic in Boulder City. The objectives described in the purpose and need for the
Hoover Dam Bypass—reducing travel time, eliminating substandard design geometry at
the dam and approaches, increasing public safety at the dam, and enhancing visitor
experience at the dam—would not be achieved by routing traffic around Boulder City or
making other improvements in the Boulder City/U.S. 93 Corridor.

1.6.3 Arizona

The Arizona State Transportation Improvement Plan (ASTIP) (ADOT, December 1994) has '
identified the Phoenix to Nevada (U.S. 93) corridor as one of the top priority corridors
within Arizona. The document states:

"Existing concerns within the Phoenix to Nevada corridor include the levels of recreation
travel and trucking usage with the resulting conflicts and safety concerns. Long-term
economic opportunities exist in this corridor, particularly as it relates to completion of a
Mexico-Canada link and improvements of access and travel opportunities in Northwest
Arizona."

The U.S. 93 corridor connects Phoenix to 1-15 in southern Nevada and has been designated
by ADOT to become Arizona's link in the international trade route proposed by NAFTA.
ADOT has programmed over $160 million to improve U.S. 93 as a four-lane divided facility
from the Phoenix area to north of Kingman, Arizona, within the next several years. ADOT
has also programmed $300,000 to begin studies for improving U.S. 93 from MP 0 to MP 15
in the LMNRA.

1.7 Legislation Regarding the Proposed Project

The following sections summarize legislation regarding the proposed project. '
SCO/CHAP-1.WPD/003672773 1-21
-------
CHAPTER 1 PURPOSE AND NEED
1.7.1 Hoover Powerplant Act (Public Law 98-381)

The Hoover Powerplant Act was passed in 1984, and it authorized Reclamation to construct
this bridge project. The authorizing legislation specifically prohibits construction of the
project through reimbursement from power generation at the dam.

1.7.2 Nevada Senate Joint Resolution 26

This Resolution, dated June 19,1995, urges Congress to take necessary actions to alleviate
problems caused by heavy commercial traffic over Hoover Dam. This remedy includes
constructing a highway bypass around Hoover Dam to:

• Divert the heavy flow of trucks transporting highly flammable or hazardous materials,
or both, and the heavy flow of regular traffic from traveling over Hoover Dam

• Prevent further air pollution of the area

• Reduce traffic accidents in the area

• Reserve the portion of U.S. 93 over Hoover Dam to accommodate dam tourists

• Prevent Colorado River pollution resulting from potential spills resulting from heavy
traffic flow

1.7.3 Nevada Senate Concurrent Resolution 60

This Resolution, dated June 19,1995, directed the Nevada Department of Motor Vehicles
and Public Safety and the Public Service Commission of Nevada to jointly study current
regulations governing the transportation of hazardous materials from Arizona to Nevada
via U.S. 93 over Hoover Dam; it further directed NDOT to study the feasibility of
prohibiting commercial traffic over Hoover Dam, and to study methods of financing road
and highway construction projects to divert commercial traffic from traveling over
Hoover Dam (see Section 2.5).

1.7.4 Transportation Equity Act for the 21st Century (TEA-21)

This legislation was approved with broad congressional support and was signed into law
by President Clinton on June 9,1998. It reauthorizes the Federal transportation program for
years 1998 through 2003.

The legislation authorizes $10 million specifically for the Hoover Dam Bypass project under
Arizona High Priority Project 383 and another $31 million under Arizona High Priority
Project 1814. In Fiscal Year (FY) 1999, two FHWA discretionary programs allocated
additional funds—$4 million from the Public Lands Highway program and $2 million from
the National Corridor and Development Program. In FY 2000, the project received $6
million from the Public Lands Highway program and $2 million from the National Corridor
and Development Program. An additional $3 million was appropriated in FY 2001 as an
add-on to a Defense Bill. In addition, an FY 2001 DOT appropriation included $20 million
for the project. The legislation also makes the Hoover Dam Bypass project eligible for
additional Federal funding on a year-by-year basis under the Federal Lands Highway
Program and the National Corridor Planning and Development Program.
1 -22 SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 1 PURPOSE AND NEED
1.8 Relationship of the Proposed Project to Other Modes of

Transportation

U.S. 93 does not currently serve airports, rail or port facilities, bike routes, or mass transit
services near Hoover Dam. The NFS, in partnership with Reclamation, is planning to
establish a bicycle/pedestrian trail that will extend from Boulder City, Nevada, to Hoover
Dam. This approved trail will parallel U.S. 93 along the Old Government Railroad grade.
As discussed previously, a high-volume mix of passenger, freight, and recreational vehicles
in addition to many pedestrian tourists on the dam crest crosses Hoover Dam daily.
SCO/CHAP-1 .WPD/003672773 1'23
-------
CHAPTER 1 PURPOSE AND NEED
This page intentionally left blank.
1 -24 SCO/CHAP-1 .WPD/003672773
-------
CHAPTER 2
Alternatives
2.1 Introduction

This chapter describes project alternatives being evaluated, previous studies of those
alternatives, screening criteria developed to aid in selecting alternatives to be evaluated, the
preferred alternative, and alternatives eliminated from detailed impact evaluation.

A range of alternatives was considered, and the identification of a preferred alternative was
not made until the alternatives' impacts and comments on the DEIS and from the public
hearings were fully evaluated (see Section 2.6.2). The four most reasonable alternatives
fully evaluated (including the No Build Alternative) were developed to a comparable level
of detail in the DEIS so that their comparative merits could be analyzed.

2.2 Initial Identification of Alternatives

Study summaries in Table 1-1 include descriptions of potential build alternatives that were
identified during the public meetings conducted for this EIS. Figure 2-1 shows alignments
of these alternatives. In addition, a No Build Alternative is considered. The following
sections briefly describe these alternatives.

2.2.1 Promontory Point

This alternative crosses Lake Mead about 1,000 feet upstream from Hoover Dam and
requires constructing approximately 2.7 miles of highway approach in Nevada, a
2,200-foot-long bridge, and a 0.9-mile highway approach in Arizona.

2.2.2 Sugarloaf Mountain (Preferred Alternative)

This alternative crosses the Colorado River about 1,500 feet downstream from Hoover Dam
and requires constructing approximately 2.2 miles of highway approach in Nevada, a
1,900-foot-long bridge, and a 1.1-mile highway approach in Arizona. Sugarloaf Mountain
has been identified as the preferred alternative (see Section 2.6.2.1).

2.2.3 Gold Strike Canyon

This alternative crosses the Colorado River about 1 mile downstream from Hoover Dam
and requires constructing approximately 2.2 miles of highway approach in Nevada, a
1,700-foot-long bridge, and a 1.1-mile highway approach in Arizona.

2.2.4 Boulder City North

This alternative crosses the Colorado River about 2.5 miles downstream from Hoover Dam
and requires constructing approximately 5.6 miles of highway approach in Nevada, a
2,200-foot-long bridge, and a 2.1-mile highway approach in Arizona.
SCO/CHAP-2.WPD/003672774 2-1
-------
CHAPTER 2 ALTERNATIVES
2.2.5 Boulder City South

This alternative crosses the Colorado River about 2.5 miles downstream from Hoover Dam
and requires constructing approximately 9.4 miles of highway approach in Nevada, a
2,200-foot-long bridge, and a 2.1-mile highway approach in Arizona.

2.2.6 Boulder City South Option

This alternative crosses the Colorado River about 2.5 miles downstream from Hoover Dam
and requires constructing approximately 8.8 miles of highway approach in Nevada, a
2,200-foot-long bridge, and a 2.1-mile highway approach in Arizona.

2.2.7 Willow Beach North

This alternative crosses the Colorado River about 8 miles downstream from Hoover Dam
and requires constructing approximately 13 miles of highway approach in Nevada, a
2,000-foot-long bridge, and a 4-mile highway approach in Arizona.

2.2.8 Willow Beach South

This alternative crosses the Colorado River about 14 miles downstream of Hoover Dam and
requires constructing approximately 14.3 miles of highway approach in Nevada, a
2,080-foot-long bridge, and 8 miles of highway approach in Arizona.

2.2.9 Temple Bar

This alternative begins at 1-15, approximately 30 miles northeast of Las Vegas. The
alignment would proceed in a southeast direction and would require a long bridge to span
the "Narrows" in Lake Mead. From the "Narrows," the alignment would generally follow
the existing road corridor west of Detrital Wash until it ties with U.S. 93 near the LMNRA
boundary. This alternative requires the construction of approximately 28 miles of new road
north of Lake Mead and 26 miles of new road along the existing road corridor between Lake
Mead and the tie to U.S. 93 in Arizona.

2.2.10 Nelson

This alternative begins at the U.S. 93/U.S. 95 interchange west of Boulder City. It follows
the U.S. 95 corridor for 10 miles and then the NV 165 corridor for approximately 20 miles.
A new bridge across the Colorado River, 21 miles downstream of Hoover Dam, would be
constructed. Approximately 12 miles of new road construction through previously
undisturbed lands would be required on the Arizona side to tie back in with U.S. 93 about
40 miles north of Kingman.

2.2.11 Cottonwood

This alternative begins at the U.S. 93/U.S. 95 interchange west of Boulder City and proceeds
southerly to Searchlight for approximately 35 miles. The alternative then proceeds easterly
for approximately 14 miles, along the existing road corridor to Cottonwood Cove. A new
bridge across Lake Mohave and an additional 26 miles of construction would be required
on the Arizona side to tie back in with U.S. 93 about 24 miles north of Kingman.
2-2 SCO/CHAP-2.WPD/003672774
-------
LasVeg
HOOVER
DAM
COLORADO RIVER
Alternatives Evaluated
In Detail
1 Promontory Point
e
from D&taiied Svaluatiors
4 Boulder City North
5 Boulder City South
Late Mead National
Recreation Arm
Boundary
6 Boulder City South Option
7 Willow Beach North

9 Tempi® Bar Corridor
10 Ifeison Corridor
11 Cottonwood Corridor
12 Leughtsn/BulShsEd City Corridor
13 U.S. 95/1-40 Corridor
14 vsyf
Golden
Shores
\
t«SS3,1ZPM Z4W 88(1/86)
FIGURE 2-1
ALTERNATIVES CONSIDERED
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-3
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
2.2.12 Laughlin-Bullhead City

This alternative to U.S. 93 improves the existing route between Boulder City and Kingman
via Laughlin and Bullhead City. This alternative uses existing U.S. 95, SR163, and SR 68. It
requires widening approximately 55 miles of U.S. 95 and 14.5 miles of SR 68 to four lanes,
adding more pavement to the existing lanes, and constructing a new multi-span bridge
crossing the Colorado River between Davis Dam and the existing Laughlin Bridge. This
alternative restricts truck traffic from crossing Hoover Dam and reroutes the traffic along
the corridor discussed above. Passenger car traffic would not be regulated in any way.
This alternative is discussed in detail in Appendix B, Laughlin-Bullhead City Alternative.

2.2.13 U.S. 95/1-40

This alternative to U.S. 93 improves the existing route between Boulder City and Kingman
via Needles, California. Approximately 56 miles of US. 95 in Nevada and 13 miles of
U.S. 95 in California would be widened to four lanes, and existing U.S. 95 would be overlaid
with new pavement. No improvements to existing 1-40 and its crossing of the Colorado
River south of Needles are necessary.

2.2.14 Modifications to Hoover Dam

This alternative includes two options for modifying existing U.S. 93 where it crosses the
Colorado River on the crest of Hoover Dam: widening Hoover Dam and constructing an
elevated roadway on the dam.

2.2.14.1 Widening Hoover Dam
This option widens the roadway to four lanes on the dam crest and its approaches.

2.3.14.2 Elevated Roadway on Hoover Dam
This option adds an elevated crossing structure to be supported by a portion of Hoover
Dam. It also includes new and straighter highway approaches.

2.2.15 Restricting Motorized Traffic from Crossing Hoover Dam

This alternative includes two options: restricting truck traffic and restricting all vehicle
traffic from crossing Hoover Dam.

2.2.15.1 Restricting Truck Traffic Only
This option restricts truck traffic from crossing Hoover Dam by restricting specific vehicle
classifications. It diverts trucks to alternate routes, but allows automobile traffic to cross
Hoover Dam. The most likely diversions are over Davis Dam or the Laughlin Bridge.

2.2.15.2 Restricting All Traffic
This option restricts all motorized vehicle traffic from crossing Hoover Dam by diverting all
vehicles to alternate routes; it allows only bicycle and foot traffic on Hoover Dam. The most
likely diversions are over Davis Dam or the Laughlin Bridge.
SCO/CHAP-2.WPD/003672774 2-5
-------
CHAPTER 2 ALTERNATIVES
2.2.16 Traffic Systems Management

This alternative includes relatively low-cost, nonstructural improvements designed to
reduce traffic congestion, improve traffic flow, and increase existing highway capacity.
This alternative could include signs, traffic signals, turn lanes, barriers, traffic controls, and
other devices to direct traffic and pedestrians.

2.2.17 No Build

This alternative consists of no action being taken. No Hoover Dam Bypass would be
developed, no change in the current highway configuration would occur, no traffic
restrictions would be imposed, and no other structural or nonstructural improvements
would be developed on U.S. 93 near Hoover Dam.

2.3 Criteria for Screening Alternatives

After the initial identification of alternatives, criteria were developed to screen alternatives.
Comparing alternatives to the screening criteria is the process used to reduce the number of
alternatives subject to detailed environmental evaluation in this EIS. The following criteria
were used to evaluate and eliminate alternatives:

• The purpose and need (discussed in Chapter 1), including engineering and operational
standards, safety, and traffic/freight capacity, should be achieved with a reasonable
cost.

• Section 4(f) land required for a route alignment should be avoided or minimized
pursuant to Section 4(f) of the Department of Transportation Act of 1966.

• Impacts to federally and/or state listed threatened or endangered vegetation and
wildlife species and sensitive habitats, such as wetlands, should be avoided or
minimized.

• Impacts to cultural resources, including Hoover Dam (a National Historic Landmark)
and archaeological (prehistoric and historic) resources, should be avoided or minimized.

• Impacts to aesthetic resources (including visual, noise, dust, and odors) should be
avoided or minimized.

• Impacts on recreation resources and to tourists should be avoided or minimized.

2.4 Public Input

Since 1965, the public has had periodic opportunities to comment on this project. Public
involvement activities have included scoping meetings held in June 1990 in Kingman,
Arizona, and Boulder City and Las Vegas, Nevada. A Notice of Intent was published in
May 1990 to advertise the three public scoping meetings; newspaper and press releases
were also used to publicize these meetings. The Kingman meeting, held on June 6,1990,
was attended by 12 persons in addition to Reclamation representatives. Attendees
expressed interest in selecting the alternative that would solve the traffic problems and be
the least damaging environmentally. The Boulder City meeting, on June 7,1990, was
attended by 91 persons in addition to representatives from Reclamation, the State of
Nevada, NFS, and the news media. In Boulder City, there was general concurrence that a

2-6 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
new crossing was needed to remove traffic from Hoover Dam; however, the public was
divided on the solution. Some preferred to have a bypass around Boulder City in addition
to Hoover Dam, while others felt that any road that bypassed Boulder City would severely
impact downtown businesses. The Las Vegas meeting, on June 7,1990, was attended by
17 people in addition to Reclamation representatives.

A newsletter, titled Update, was published in January 1991 and sent to interested
individuals. Interviews with numerous community members and several meetings with
interested members of the public, the Boulder City Chamber of Commerce, members of the
Boulder City Council, and other organizations also occurred.

Subsequent to FHWA taking over as lead agency, meetings were held in Kingman, Boulder
City, and Las Vegas in late October 1997 to provide information and solicit input for the
environmental review process. Approximately 250 people attended and commented at the
three meetings. Most comments supported one alternative or another. In Boulder City,
many comments focused on considering other alternative crossings in addition to the three
build alternatives, specifically those to the south that would bypass Boulder City. Many
comments at all three locations raised concerns about various environmental impacts.

FHWA initiated public circulation of the DEIS on September 25,1998, with publication of
the Notice of Availability in the Federal Register. From October 13 to 15,1998, FHWA held
DEIS public hearings on successive evenings in Kingman, Arizona, and Boulder City and
Las Vegas, Nevada. Approximately 250 people attended the DEIS public hearings. The
court reporter transcripts of oral comments received at the hearings are included in
Volume II of the final EIS (FEIS). The entire DEIS was also accessible on the project web
site; by November 10,1998, the close of the DEIS comment period, the web site was
accessed over 1,500 times. There were a total of approximately 160 public and agency
commenters on the DEIS, including comments received after the close of the comment
period. See Volume n for a full description of the DEIS public input process.

2.5 Alternatives Considered but Eliminated from Detailed

Evaluation

After applying the previous screening criteria to the alternatives, all were eliminated from
further consideration except for the three alignments closest to Hoover Dam: Promontory
Point, Sugarloaf Mountain, and Gold Strike Canyon. After further analysis and evaluation
of comments received on the DEIS, Sugarloaf Mountain was identified as the preferred
alternative based on these and other criteria. The other alternatives were eliminated for
reasons described below and summarized in Table 2-1.

1. Some alternative routes did not meet the project purpose and need because they would
not substantially eliminate roadway deficiencies and reduce traffic congestion on
U.S. 93 at Hoover Dam and the dam approaches, eliminate through traffic from the
dam, enhance public safety, or protect Hoover Dam and its visitors. Alternatives were
also dropped from further consideration if they substantially increased travel time and
did not provide system continuity to enhance travel within the U.S. 93 NAFTA corridor.
The Laughlin and U.S. 95/1-40 Alternatives were eliminated because motorists would
avoid driving the additional 23 and 70 miles, respectively, by continuing to use the
Hoover Dam crossing. Therefore, meeting the objectives of enhanced safety and
reduced congestion on U.S. 93 at the dam would not be achieved. As described in

SCO/CHAP-2.WPD/003672774 2-7
-------
CHAPTER 2 ALTERNATIVES
Appendix B, Laughlin-Bullhead City Alternative, the Laughlin Alternative would not
improve the LOS on U.S. 93 on Hoover Dam.

2. Section 4(f) of the U.S. Department of Transportation Act of 1966 (49 U.S.C. §303)
declares that, "it is the policy of the United States government that special effort should
be made to preserve the natural beauty of the countryside and public park and
recreation land, wildlife and waterfowl refuges, and historic sites." Section 4(f) specifies
that the Secretary of Transportation may approve a transportation program or
project—requiring the use of 4(f) land only if:

1. There is no feasible and prudent alternative to using that land; and

2. The program or project includes all possible planning to minimize harm to the park,
recreation area, wildlife and waterfowl refuge, or historic site resulting from the use

Many alternatives would affect these lands; however, some routes have considerably
more impact than others (Reclamation, July 1993). The Temple Bar Alternative and all
the highway alternatives south of Gold Strike Canyon except the Laughlin and
U.S. 95/1-40 Alternatives would affect much more Section 4(f) land than the three
northern alternatives near Hoover Dam. Based on the requirement to minimize harm to
Section 4(f) property, these southerly alternatives were eliminated from further
consideration.

3. Routes nearest Hoover Dam would pass through lands already extensively disturbed by
human-made features. Conversely, the Willow Beach, Nelson, Cottonwood, Boulder
City, and Temple Bar Alternatives were eliminated because those routes would pass
through areas of extensive pristine habitat.

5. The cost of constructing the routes would increase as the distance away from the dam
increases because longer sections of new highway would be required; therefore, longer,
more costly alternatives were eliminated. The Laughlin-Bullhead City Alternative, for
example, would cost an estimated $130 million to construct and an additional
$87 million for improvements that are programmed based on existing needs, versus
$198 million to $215 million for alternatives closer to Hoover Dam (see Appendix B,
Laughlin-Bullhead City Alternative). Furthermore, considering traffic volumes over a
20-year period, an additional $1.4 billion in total user costs would be incurred due to the
increased length of the Laughlin-Bullhead City Alternative (see Appendix B).

6. Alternatives that require keeping the existing highway open to through traffic to
provide visitor access to the dam were dropped from further consideration if they also
required operating and maintaining extensive lengths of duplicate highway.
Alternative routes not dose to Hoover Dam (Willow Beach, Nelson, Cottonwood, and
Temple Bar) were eliminated for this reason.

7. Restricting truck traffic does not fully meet two critical elements of the project purpose
and need; it removes only a portion of the truck traffic contributing to Hoover Dam
congestion and results in a substantial increase in travel distance and time for truck
traffic. Additionally, closing the dam to commercial truck traffic is subject to FHWA

2-8 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
approval under the provisions of Title 23 of the Code of Federal Regulations (23 CFR).
23 CFR Section 658.11 pertains to additions and deletions of roads on the National
Network of Highways, of which U.S. 93 is a part. The NDOT prepared a preliminary
evaluation of criteria for network deletion of U.S. 93 as specified by 23 CFR and
concluded it would not be feasible to remove the route from the National Network of
Highways. Consequently, NDOT concluded it is not feasible to prohibit commercial
trucks from crossing Hoover Dam unless a practical alternative crossing is provided.

8. Restricting all traffic from Hoover Dam, with the exception of bicycle and foot traffic,
was eliminated because it does not meet the need to remove a major bottleneck to
interstate and international commerce. Further, this alternative would not meet other
critical elements of the project purpose; specifically, it would not reduce traffic
congestion and accidents near the dam on the major commercial route between Phoenix
and Las Vegas, and it would not reduce vehicle travel time or improve speed.

9. Alternatives related to Hoover Dam widening were eliminated from further
consideration for technical, economic, and cultural reasons. Because tourist traffic
would not be separated from through traffic, this option does not solve the public safety
problem, and does not protect power and water supplies. No practical way exists to
modify Hoover Dam without impacting the historic appearance of the dam or
disrupting traffic during construction.

Attaining the required highway design criteria by adding an elevated crossing structure
(which would be supported by some portion of Hoover Dam) would require new and
straighter highway approaches. Deep and lengthy excavations, or possibly tunnels, are
necessary to connect such a structure to the existing highway. Support piers for the
elevated structure would cause traffic interference during construction and would
permanently affect the space available on the dam crest for tourist movement and dam
maintenance operations.

Concerns identified with both dam modification options also include interference with
existing transmission lines, towers, and other power facilities; impacts to the historical
significance of the site (the integrity and setting of the dam and its status as a NHL); and
limited space available for separating traffic, vehicle turning movements, and parking
maneuvers.
Table 2-1 summarizes the results of applying screening criteria and rationale for eliminating
certain alternatives.

2.6 Alternatives Studied in Detail

Three build alternatives met the screening criteria and were studied to a feasible level of
engineering design and cost analysis/including line-item estimates, as described in the 1992
Phase B Corridor Studies report. For these three alternatives, a new four-lane highway and
four-lane bridge would be constructed near Hoover Dam (see Figure 2-2, showing the
typical roadway section). Current highway design standards for a 60-mph design are
proposed for all three build alternatives. The Nevada and Arizona connections of the old
highway/dam crossing to the new U.S. 93 bypass roadway will be designed to provide
ingress/egress for bicycles. Detailed traffic analysis will be completed during final design
SCO/CHAP-2.WPD/003672774 2-9
-------
CHAPTER 2 ALTERNATIVES
Table 2-1
Comparison of Alternatives Considered

I
I
I

Alternative Name
Promontory Point
Sugarloaf Mountain (Preferred)
Gold Strike Canyon

Boulder City North
Boulder City South
Boulder City South Option
Willow Beach North
Willow Beach South
Nelson
Cottonwood
Laughlin-Bullhead City
U.S. 95/I-40
Temple Bar
Modifications to Hoover Dam
Restricting Motorized Traffic to
Hoover Dam
Traffic Systems Management
4(f) Lands
Potentially
Disturbed (acres)
74
92
128

145
165
135
405
575
491
436
36
0
818
n/a
n/a

n/a
Distance from the
U.S. 93/95
Interchange NV to
Kingman, AZ (mites)
83
83
82

82
83
82
81
80
82
99
106
153
149
n/a
n/a

n/a
Results of Applying
Screening Criteria
Meets criteria
Meets criteria
Meets criteria
Reason for Elimination
2,3,4
2,3,4
2,3,4
2, 3, 4, 5, 6
2, 3, 4, 5, 6
2, 3, 4, 5, 6
2, 3, 4, 5, 6
1.4,5
1,5
2, 3, 4, 5, 6
1,9
1,7,8

1,7,8
Screening Criteria
1. Does not meet purpose and need.
2. Substantial Section 4(f) Impacts.
3. Severe impacts to pristine habitat
4. Severe impacts to wildlife.
5. Excessive costs.
6. Requires operation and maintenance of duplicate parallel roadways.
7. NOOT determined a commercial truck ban infeasible.
8. No reduction in congestion.
9. Does not solve public safety problem or protect power and water supplies; impacts to historic appearance of dam.
to determine whether at-grade crossings or interchanges are required at or near the project
termini. Provision of an interchange connection of existing U.S. 93 with the new Hoover
Dam Bypass at or near the western project terminus (east of the Hacienda Hotel) will
remove the need for an interchange connection at the Reclamation warehouse, where both
the Sugarloaf Mountain and Promontory Point alignments cross existing U.S. 93 (see
Figure 2-3). Under the build alternatives, commercial trucks will be restricted from Hoover
Dam according to vehicle weight or number of axles; local delivery trucks and
2-10
SCO/CHAP-2.WPD/003672774
-------
SHOULDER
VARIES, 0'-8'
EXISTING PAVEMENT
Existing Typical Section
R/W
150'
150'
R/W
10' SHOULDER

TWO 12' LANES = 24' J ^6'-9' (VARIES)
-CUT SLOPE VARIES
1/4:1 (ROCK) TO 6:1
SLOPE VARIES
1-1/2:1 TO 6:1-
Proposed Typical Section
GENERAL NOTES

1 High quality rock is expected throughout the majority of the study area. Cut slopes
vary depending on rock type. Though not shown, widened ditches may be required
in areas of very deep cut In addition, rockfall areas may need special catchment
ditches and/or concrete barrier rail instalations to protect the highway and its users.

2. More detailed typical sections are depicted in the Phase B Corridor Studies.

3. Two-lane existing typical section shown. Some portions of existing road include a
climbing lane.

142883.12.PM 2439.25(7/9/98)
FIGURE 2-2
TYPICAL ROADWAY SECTION
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

2-11
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-12 SCO/CHAP-2.WPD/003672774
-------
LAKEMEADHATONAL
RECREATION AREA
,«' I
LAKE HEAD NATIONAL
RON ARE*
LAKE MEAD NATIONAL
RECREATION AREA

POTENTIAL
INTERCHANGE
860 1300 FEET
KSi^Sa
8CW.E IB APPROXIMATE
PHOMOWtWY POINT ALTERNATOE
SUOanLOAP MOUNTAIN ALTERNATIVE

GOLD STMKE CANYON ALTERNATIVE

THAU

U.S 9S

HOOVEH DAM RESERVATION BOUNDARY
NM10NALHISTORIC LANDMARKBOUNDAm
FIGURE 2-3
ALTERNATIVES BEING
EVALUATED IN DETAIL
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-14 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
administrative/maintenance trucks would be exempted. The No Build Alternative is also
described. The following alternatives are shown in Figure 2-3 and are described in the
following sections:

• Promontory Point
• Sugarloaf Mountain (Preferred Alternative)
• Gold Strike Canyon
• No Build (Existing U.S. 93)

During the 1992 Colorado River bridge crossing study conducted by Reclamation, generic
bridge designs that were determined to be suitable were presented as viable structure
alternatives for each river crossing. Presentation of specific bridge designs in this EIS is not
intended to preclude other feasible structures. A Design Advisory Panel (DAP), established
as part of a Programmatic Agreement (PA) for this project under requirements of the
National Historic Preservation Act (NHPA), will provide input on bridge design concepts,
structure type, and materials (see Section 3.5). The DAP consists of members from FHWA,
NDOT, ADOT, the Nevada and Arizona State Historic Preservation Offices, the Advisory
Council on Historic Preservation, the National Historic Landmark Coordinator, NPS,
Reclamation, WAP A, and consulting Native American tribes, as well as an independent
architectural historian and a registered landscape architect. The FHWA will establish a
project development schedule, with design review milestones acceptable to the DAP. The
DAP will provide input on bridge design concepts, addressing structure type and materials,
in light of the historical visual context of the Hoover Dam National Historic Landmark
(HDNHL). The DAP will also provide input on corridorwide design elements, with the
goal of developing acceptable aesthetic and material treatments throughout the bypass
corridor to mitigate the total project effects on the HDNHL and other proximate historic
properties. The DAP, with FHWA as the lead agency, also will be responsible for
development of a process for public involvement as design concepts evolve.

The cost estimates shown for the alternatives studied in detail are based on the Reclamation
Phase B Study of August 1992. The estimates shown in the Phase B Study were actually
computed in 1991. Therefore, costs were inflated at 4 percent per year for 11 years,
establishing a base year of 2002.

2.6.1 Promontory Point Alternative

The Promontory Point Alternative crosses Lake Mead about 1,000 feet upstream of Hoover
Dam. This alternative requires constructing approximately 2.7 miles of highway approach
in Nevada, a 2,200-foot-long bridge, and an approximately 0.9-mile highway approach in
Arizona (Figure 2-4).

2.6.1.1 New Highway
The new highway begins about 1,000 feet east of the Hacienda Hotel, following a route just
south of existing U.S. 93 to the Reclamation warehouse area. This route traverses the
hillside just north of the present Reclamation service road, and follows about the same
alignment as the existing service road for approximately 1,300 feet. The highway grade
through this segment is about 1 percent as it continues its descent. After crossing the north
end of the switchyard, the highway intersects a high narrow ridge, and crosses over a mass
of rock fragments below cliffs, descending on a 5 percent grade for a distance of about
2,000 feet to a long-span bridge crossing at Lake Mead.
SCO/CHAP-2.WPD/003672774 2-15
-------
CHAPTER 2 ALTERNATIVES
On the Arizona side of the bridge, the highway traverses an area requiring a deep cut, then
follows along the side of a high bluff. The highway then descends at a 6 percent grade to
the intersection with existing U.S. 93. A frontage road, approximately 1,700 feet long, must
be constructed to provide continued access to the dam for recreation, operation, and
maintenance.

2.6.1.2 Bridge Designs
Three bridge designs were initially studied for the Promontory Point Alternative: a
concrete cable-stayed bridge, a steel truss rib through-arch bridge, and a suspension bridge
(see Figures 2-5,2-6, and 2-7). The design elevation at the center of the proposed bridge
would be 1,463 feet, about 273 feet above the normal water surface elevation of Lake Mead
and 231 feet higher than the elevation of the current highway across Hoover Dam.

2.6.1.3 Other Features
This alternative requires several project features in addition to the proposed highway and
bridge crossing Lake Mead. These other features include the following:

• A 400-foot-long highway bridge crossing a bend in Gold Strike Canyon

• A 300-foot-long runnel passing through a high, narrow ridge separating the canyon from
the open valley to the northeast

• Wildlife crossings, provided by six underpasses, two overpasses, and the top of one
tunnel functioning as an overpass, fencing to guide wildlife to the crossing structures,
fencing to continue approximately 2,400 feet beyond the intersection of the new highway
with existing U.S. 93 in Arizona, and out-jumps (mounds adjacent to fences) to allow
bighorn sheep to exit the fenced highway right-of-way.

2.6.1.4 Project Construction
The Promontory Point Alternative requires 5 years to construct. Assuming that funding
becomes available and environmental clearances are obtained, the project would be
completed by 2007. The estimated cost of this alternative is $204 million, including
preliminary and construction engineering.

No major detours, closures, or traffic delays are expected to occur during construction of the
lake bridge and highway approaches. The existing highway could remain open with
minimal interference, except during construction at the beginning and ending locations of
the project. Construction specifications for the project would provide for maintaining two
traffic lanes during construction. In Arizona, the access road must be completed before the
existing highway is closed to public traffic.

| 2.6.2 Sugarloaf Mountain Alternative (Preferred Alternative)

The Sugarloaf Mountain Alternative crosses the Colorado River about 1,500 feet
downstream of Hoover Dam. This alternative requires constructing approximately
2.2 miles of highway approach in Nevada, a 1,900-foot bridge, and an approximately
1.1-mile highway approach in Arizona (Figure 2-8).
2-16 SCO/CHAP-2.WPD/003672774
-------
LEGEND
X
z
PROMOMTORY POINT ALTERNATIVE

HIGHWAY 93

BIGHORN SHEEP OVERPASS

BIGHORN SHEEP UNDERPASS
END
PROJECT
1000 2000 FEET
SCALE IS APPROXIMATE

1428831505 J439_10B3jOO
FIGURE 2-4

PROMONTORY POINT

PROJECT FEATURES
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-17
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-18 SCO/CHAP-2.WPD/003672774
-------
14268312PM PHQTOA7 9/98
FIGURE 2-5
PROMONTORY POINT

SUSPENSION BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-19
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-20 SCO/CHAP-2.WPD/003672774
-------
142883.12.PM PHOTOA6 9/98
FIGURE 2-6
PROMONTORY POINT

CABLE-STAYED BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

2-21
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-22 SCO/CHAP-2.WPD/003672774
-------
142B83.12.PM PHOTOA5 9/98
FIGURE 2-7
PROMONTORY POINT
STEEL TRUSS RIB THROUGH
ARCH BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-23
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-24 SCO/CHAP-2.WPD/003672774
-------
LEGEND

•--—•-— SUGARLOAF MCXJNTAIN ALTERNATIVE

— HIGHWAY 93

Z BIGHORN SHEEP OVERPASS

Z BIGHORN SHEEP UNDERPASS
1000 2000 FEET
SCALE IS APPROXIMATE

1428631505 2439.1 Sail 3/00
END
PROJECT
FIGURE 2-8
SUGARLOAF MOUNTAIN

PROJECT FEATURES
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

2-25
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-26 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
2.6.2.1 Basis for Identification as the Preferred Alternative

The criteria used in screening the alternatives are described in Section 2.3. The following
discussion summarizes the suitability of each of the Hoover Dam Bypass alternatives based
on these criteria. A seventh criterion has been added to account for the public and agency
input received during circulation of the DEIS.

Criterion 1. The purpose and need, including engineering and operational standards, safety,
and traffic/freight capacity, should be achieved with a reasonable cost.

The No Build Alternative (No Build) does not meet the purpose and need of the project (as
discussed in Section 2.7). All three "build" alternatives meet the purpose and need of the
project The Sugarloaf Mountain and Promontory Point Alternatives have the best roadway
geometry; however, the Promontory Point Alternative has a curve at each end of the
proposed bridge/whereas the Sugarloaf Mountain Alternative has long, straight approaches
to the bridge. This maximizes sight distance and minimizes the possibility of an accident at
the Sugarloaf Mountain Alternative bridge. Numerous agencies and citizens opposed the
Promontory Point Alternative because of the risk of a hazardous material spill into Lake
Mead.
The Gold Strike Canyon Alternative, although 0.1 mile shorter than Sugarloaf Mountain
and 0.6 mile shorter man Promontory Point, has the poorest horizontal and vertical
alignments. It also has a curve at each end of the proposed bridge. The profile grade is by
far the worst of the three build alternatives and includes more than 2.5 miles of grades
steeper than 5 percent. The Promontory Point Alternative and the Sugarloaf Mountain
Alternative have only 0.5 mile of grades steeper than 5 percent. Gold Strike Canyon
requires the construction of 10 bridges in addition to the Colorado River Bridge, whereas
Promontory Point has 1 additional bridge and Sugarloaf Mountain has 2 additional
bridges. As shown in Figures 2-4,2-8, and 2-11, each of the three build alternatives would
also require one relatively short tunnel.

Construction access and constructability of the Gold Strike Canyon Alternative are the most
difficult, although these criteria are difficult to quantify. Gold Strike Canyon is also the
most expensive at $215 million, although it is only 9 percent higher than the Sugarloaf
Mountain Alternative, which is $198 million. The cost of the Promontory Point Alternative
is $204 million.

The .preferred alternative under this criterion is the Sugarloaf Mountain Alternative.

Criterion 2. Impacts to Section 4(f) land (public parks, recreation areas, wildlife refuges,
and historic sites) should be avoided or minimized pursuant to Section 4(f) of the
Department of Transportation Act of 1966.

There are no feasible and prudent alternatives that avoid the use of Section 4(f) land (see
Chapter 6). Although the Promontory Point Alternative uses 74 acres of Section 4(f) land
and the Sugarloaf Mountain Alternative uses 92 acres, the Sugarloaf Mountain alignment
has been determined to be the harm-minimizing alternative based on the following key
factors:

• Strong public concern regarding hazardous materials spills in Lake Mead and resulting
impact on LMNRA with the Promontory Point bridge
SCO/CHAP-2.WPD/003672774 2-27
-------
CHAPTER 2 ALTERNATIVES
I* Resource and regulatory agency support for Sugarloaf Mountain due to least impact to
wildlife, wildlife habitat, and water quality

| • No adverse impact to the "first impression" historic views of Hoover Dam

* Ability to more readily blend the Sugarloaf Mountain Alternative into the landscape

• Sugarloaf Mountain Alternative traverses the National Register-eligible TCP in an area of
extensive disturbance

• Ability to minimize and mitigate impacts through continuing consultation and Native
American participation on the DAP

The Gold Strike Canyon Alternative uses 128 acres of Section 4(f) land, impacts existing
recreational use, substantially impairs pristine scenic conditions, and has a substantial and
potentially unmitigable impact on the Gold Strike Canyon TCP. Therefore, it cannot be
considered the haim-rrunimizing alternative.

Criterion 3. Impacts to federally and/or state-listed threatened or endangered vegetation
and wildlife species and sensitive habitats, such as wetlands, should be avoided or
minimized.

The Gold Strike Canyon Alternative involves constructing through previously undisturbed
areas, whereas the Sugarloaf Mountain and Promontory Point Alternatives are generally
located along existing road corridors or through other disturbed areas. Therefore, the Gold
Strike Canyon Alternative has substantially more impacts under this criterion. NFS, the
U.S. Fish and Wildlife Service (USFWS), the Nevada Division of Wildlife (NDOW), and the
Arizona Game and Fish Department (AGFD) are opposed to the Gold Strike Canyon
Alternative.

Because of the least impacts to the peregrine falcon, desert bighorn sheep, and desert
tortoise, the Sugarloaf Mountain Alternative is preferred under this criterion.

Criterion 4. Impacts to cultural resources, including Hoover Dam NHL and archeological
(prehistoric and historic) resources, should be avoided or minimized.

The "build" alternatives adversely affect between 6 and 10 historic properties, including a
Traditional Cultural Property (TCP), although the Gold Strike Canyon Alternative is
considered to have the least historic impacts because it is located the farthest from Hoover
Dam. The Promontory Point and Sugarloaf Mountain Alternatives have an adverse effect
on the "historic" setting of Hoover Dam. Consultation with the Native American tribes
indicates that the tribes generally do not support any of the "build" alternatives; however,
when asked about a preference, they favored the Promontory Point Alternative and
strenuously opposed the Gold Strike Canyon Alternative because of significant disturbance
to the TCP.

Therefore, the Gold Strike Canyon Alternative has the least historic impacts but has the
greatest TCP concerns. The Promontory Point and Sugarloaf Mountain Alternatives have
the greatest historic concerns (from a visual standpoint).

Consequently, only the No Build Alternative can be considered to meet this criterion;
however, it does not meet the purpose and need of the project.
2-28 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
Criterion 5. Impacts to aesthetic resources (including visual, noise, dust, and odors) should
be avoided or minimized.

All of the "build" alternatives will enhance the visitors' experience at Hoover Dam since
truck traffic and much of the vehicular traffic will be removed from the dam. The Gold
Strike Canyon Alternative is the only alternative that results in a substantial noise increase
over existing levels; however, the Gold Strike Canyon Alternative is preferable for the
visitors' experience at Hoover Dam since it moves the traffic out of sight and farther away
than the other two alternatives. Traffic-generated noise, dust, and odors would be
minimized. The number of hikers and recreationists downstream from Hoover Dam is very
small compared to the number of visitors at Hoover Dam; therefore, under this criterion, it
is reasonable to select an alternative which minimizes impacts and maximizes benefits for
the visitors at Hoover Dam.

The Gold Strike Canyon Alternative is considered the preferred alternative under this
criterion.

Criterion 6. Impacts on recreation resources and to tourists should be avoided or
minimized.

All of the "build" alternatives will have a major beneficial effect on recreation and
tourism—primarily for the visitors at Hoover Dam. The visitors' experience at Hoover Dam
will be enhanced by removing the truck traffic and much of the vehicular traffic from the
crest of the dam. The Gold Strike Canyon Alternative has the greatest negative impact on
recreation since the hot springs hiking trail would be dosed during construction. The Gold
Strike Canyon Alternative would also have a long-term effect on the hiking trail because the
highway would be adjacent to or bridged over the trail for most of its length. The
Promontory Point Alternative has the most potential impact to the planned bicycle path
along the historic railroad grade north of the Reclamation warehouse area. It also has the
most impact to water recreation since boating restrictions would be implemented during
construction.

The Sugarloaf Mountain Alternative is the preferred alternative under this criterion. |

Criterion?. Public and agency input should be taken into consideration. \

The approximately 160 commenters on the DEIS favored the Sugarloaf Mountain
Alternative over either of the other two "build" alternatives and the No Build Alternative
by a three to one margin (see Section 2.4 and FEIS Volume IT). Public comments supported
the Sugarloaf Mountain Alternative because of its lowest cost and least environmental
impacts. Numerous citizens expressed concerns about the Promontory Point Alternative
because of the possibility of a hazardous material spill into Lake Mead. The resource and
regulatory agencies, with the exception of the SHPOs, unanimously supported the
Sugarloaf Mountain Alternative because of its least impact to wildlife, wildlife habitat,
water quality, and jurisdictional waters of the United States (U.S.). The Sugarloaf Mountain
Alternative is the preferred alternative under this criterion. Gold Strike Canyon was widely
disfavored due to the adverse effects on pristine habitat and recreation area.

Table 2-2 shows which alternative is favored for each of the specific criteria discussed
above. The Sugarloaf Mountain Alternative is dearly the preferred alternative using the
screening criteria established in the DEIS. Chapter 3 describes the proposed mitigation
measures for the preferred alternative.

SCO/CHAP-2.WPD/003672774 2-29
-------
CHAPTER 2 ALTERNATIVES
Table 2-2
U.S. 93 - Hoover Dam Bypass Alternative Preference by Individual Criteria

Public/
Engineering Section Aesthetic/ Agency
Alternative &Cost 4ffl Biological Cultural Visual Recreation Opinion
| No Build

| Promontory Point

I Sugarioaf Mountain

I Gold Strike Canyon
• Does not meet the purpose and need of the project (see Section 2.7).

2.6.2.2 New Highway
Similar to the Promontory Point Alternative, the Sugarioaf Mountain Alternative begins
about 1,000 feet east of the Hacienda Hotel, following a route just south of existing U.S. 93
to the Reclamation warehouse area. The highway grade then steepens to 3 percent, passes
through a gap in the high rock ridge that parallels the river, and then descends to the
southeast to the long-span bridge over the Colorado River. Depending on the final design
details, the new bypass roadway would probably cross U.S. 93 at two locations on
grade-separated structures and traverse the Reclamation property east of the warehouse.
Existing U.S. 93 would continue to provide access to Hoover Dam, Lakeview Point, and the
Reclamation warehouse (see Figure 2-4).

From the Arizona end of the proposed river bridge, the highway traverses a deep cut along
the north slope of Sugarioaf Mountain. The highway then passes through an area
containing two existing sewage evaporation ponds mat Reclamation owns and operates. To
the east of the sewage ponds, the highway turns south, crosses a wide ravine at a 6 percent
downgrade, and intersects existing U.S. 93 approximately 1.1 miles from the dam.

2.6.2.3 Bridge Designs
Bridge design options initially studied for the Sugarioaf Mountain Alternative include: a
concrete or steel deck arch bridge and a concrete cable-stayed bridge (see Figures 2-9 and
2-10). Other feasible bridge design types will be considered during final design. The
design elevation at the center of the proposed bridge is 1,486 feet, about 836 feet above the
water surface of the Colorado River and 254 feet higher than the elevation of the existing
highway across Hoover Dam.

2.6.2.4 Other Features
This alternative requires several project features in addition to the proposed highway and
bridge crossing the Colorado River. These other features include the following:

• A 400-foot-long highway bridge crossing a bend in Gold Strike Canyon

• A 300-foot-long tunnel passing through a high, narrow ridge separating the canyon from
the open valley to the northeast

• An 800-foot-long highway bridge crossing a large ravine on the Arizona highway
approach
2-30
SCO/CHAP-2.WPD/003672774
-------
FIGURE 2-9
SUGARLOAF MOUNTAIN
CONCRETE OR STEEL ARCH BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
142883.15.05 PHOTOMb fh 3100
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-32 SCO/CHAP-2.WPD/003672774
-------
1428B3.12.PM PHOTQA3 0/88
FIGURE 2-10
SUGARLOAF MOUNTAIN

CABLE-STAYED BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

2-33
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-34 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
• Sewage evaporation pond relocation

• Four wildlife underpasses, three wildlife overpasses, two additional wildlife underpasses
provided by the two bridges outlined above, one additional wildlife overpass provided
by the runnel outlined above, fencing to guide wildlife to the crossing structures, fencing
to continue approximately 2,400 feet beyond the intersection of the new highway with
existing U.S. 93 in Arizona, and out-jumps to allow bighorn sheep to exit the fenced
highway right-of-way

2.6.2.5 Project Construction
The Sugarloaf Mountain Alternative requires approximately 5 years to construct. Assuming
that funding becomes available and environmental clearances are obtained, the project
would be completed by 2007. Estimated construction cost of this alternative is $198 million,
including preliminary and construction engineering.

No major detours/ closures, or traffic delays are expected to occur during construction of the
river bridge and highway approaches. The existing highway could remain open to two-
lane traffic with minimal interference, except during construction at the beginning and
ending locations of the project and briefly during placement of girders at the two proposed
highway overpasses in the vicinity of the Reclamation warehouse.

2.6.3 Gold Strike Canyon Alternative

2.6.3.1 New Highway
From the Nevada side, about 2.2 miles of new highway follow the Gold Strike Canyon to
within about 4,000 feet of the Colorado River where it veers northeast from the canyon. The
mouth of the canyon is wide, with the sides sloping at 3 feet horizontally for about every
1 foot of elevation change. The highway reaches the 6 percent maximum grade
approximately at Station 48+00 and continues mat rate of descent for about 1.5 miles.

From the Arizona end of the proposed river bridge, the highway crosses a spoil site created
during the original Hoover Dam construction. A highway bridge spans an area between
the spoil pile and the hillside, then traverses an area of bench cut with some fills until it
bridges a ravine. The highway then turns southeast to intersect with existing U.S. 93. The
entire Arizona approach from the abutment of the river bridge on the Arizona side to the
intersection with U.S. 93 ascends at a 5.3 percent grade for a distance of about 4,000 feet.

2.6.3.2 Bridge Designs
Two bridge designs were initially studied for the Gold Strike Canyon Alternative: a
concrete deck arch and a steel deck arch (see Figures 2-12 and 2-13). The design elevation at
the center of the proposed bridge is 1,132 feet, about 482 feet above the water surface of the
Colorado River and 100 feet below the elevation of the current highway across Hoover
Dam.
SCO/CHAP-2.WPD/003672774 2-35
-------
CHAPTER 2 ALTERNATIVES
2.6.3.3 Other Features
This alternative requires several project features in addition to the proposed highway and
bridge crossing the Colorado River. These other features include the following:

• A 300-foot-long tunnel passing through a ridge that separates the canyon from the river

• Bridge structures used in areas where large roadway fills would otherwise encroach on
the Gold Strike Canyon hiking trail; retaining walls used to avoid large fills interfering
with trails and drainages

• Possible construction of noise barriers along the Gold Strike Canyon trail

• Two wildlife underpasses, 1 wildlife overpass, 10 additional wildlife underpasses
provided by the highway bridges outlined above, 1 additional wildlife overpass
provided by the tunnel outlined above, fencing to continue approximately 2,400 feet
beyond the intersection of the new highway with existing U.S. 93 in Arizona, and out-
jumps to allow bighorn sheep to exit the fenced highway right-of-way. NDOT and
ADOT will maintain the wildlife underpasses and overpasses within their respective
states.

2.6.3.4 Project Construction
The Gold Strike Canyon Alternative requires 5 to 6 years to construct. Assuming that
funding becomes available and environmental clearances are obtained, the project would be
completed by 2007. Estimated construction cost of this alternative is $215 million, including
preliminary and construction engineering.

No major detours, closures, or traffic delays would occur during construction of the bridges
and highway approaches. The existing highway remains open with minimal interference,
except at the beginning and ending points in Nevada and Arizona. The specifications for
the project provide for maintaining two traffic lanes during construction.

2.7 No Build Alternative

Under the No Build Alternative, no Hoover Dam Bypass is developed, no change in the
current highway configuration occurs, and no other structural or nonstructural
improvements are developed on U.S. 93 near Hoover Dam. Existing hairpin curves,
inadequate sight distances, narrow dam crest roadway, and steep grades on U.S. 93 in the
Hoover Dam vicinity remain unchanged. No direct construction costs result from this
alternative.

However, an increase in operations and maintenance costs is foreseeable because of
increased traffic and congestion. The public also incurs added cost because of more
frequent traffic delays and accidents.

The No Build Alternative does not meet the project purpose and need because this
alternative does not reduce traffic congestion and accidents at the dam or minimize impacts
on recreation resources and tourists; and the increased traffic volume, traveling at slower
speeds, contributes to decreased air quality in the Hoover Dam vicinity and increases
congestion for tourists at Hoover Dam and parts of the LMNRA.

The potential for a pedestrian-vehicle catastrophe or catastrophe involving vehicles
containing hazardous materials may reasonably be expected to increase with increasing

2-36 SCO/CHAP-2.WPD/003672774
-------
LEGEND
X
z
GOLD STRIKE CANYON ALTERNATIVE

HIGHWAY 93

BIGHORN SHEEP OVERPASS

BIGHORN SHEEP UNDERPASS
1000 2000 FEET
SCALE IS APPROXIMATE

142883.1505 2439_16a Ih 3/00
END
PROJECT
FIGURE 2-11

GOLD STRIKE CANYON

PROJECT FEATURES
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-37
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-38 SCO/CHAP-2.WPD/003672774
-------
M2883.12.PM PHOTOA2 9/TO
FIGURE 2-12
GOLD STRIKE CANYON

CONCRETE ARCH BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

2-39
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-40 SCO/CHAP-2.WPD/003672774
-------
142B83.12.PM PHOTOA1 9/98
FIGURE 2-13

GOLD STRIKE CANYON
STEEL ARCH BRIDGE
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
2-41
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-42 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 2 ALTERNATIVES
traffic volume. The risks to innocent bystanders, property damage to the dam and its
facilities, contamination of Lake Mead or the Colorado River, and interruption of the power
and water supplies to Southwest residents remain the same or increase.

2.8 Logical Termini

An important aspect of developing highway improvement alternatives is to define the
logical termini, or begin and end project points. All three proposed build alternatives begin
at the same point on the Nevada side, located about 1,000 feet east of the Hacienda Hotel.
All the alignments end at the same point on existing U.S. 93 on the Arizona side,
approximately at MP 1.7.

The termini of the Hoover Dam Bypass alternatives were defined to be consistent with the
project purpose and need (Chapter 1) and not necessitate other improvements outside the
defined project limits (i.e., cumulative or segmental effects). In other words, the project can
function independently for its design life, while not requiring or precluding future adjacent
highway projects. This action does not change current traffic compositions on regional
routes. Thus, it does not generate traffic on the U.S. 93 corridor or other regional routes, nor
does it predetermine the alternative selection in adjacent, but unrelated, projects. Two such
highway projects are in early planning stages: an NDOT project to address the traffic
problems along U.S. 93 in Boulder City that is coincident with the planned western
terminus of the Hoover Dam Bypass alignments; and an ADOT project to widen the
existing two-lane section of U.S. 93 south of Hoover Dam approximately 15 miles to the
existing four-lane divided highway section.

Other alternative routes to U.S. 93 between Kingman and Las Vegas exist. All require
substantial out-of-direction travel, as shown in Table 2-1. The Hoover Dam Bypass will
provide improved travel time benefits to regional traffic and freight movement among the
Phoenix, Kingman, and Las Vegas areas over the design life of the project. Improved
overland goods and freight movement is an important NAFTA goal to be achieved by the
project to eliminate the traffic bottleneck at Hoover Dam.

2.9 Toll Option

A user fee or toll charge was evaluated as an option for partially funding the new bridge
and highway approaches for each of the three build alternatives. A Traffic and Revenue
Study (Reclamation, August 1992) determined the anticipated toll revenues and the
feasibility of financing through a potential bond issue. ADOT and NDOT completed a
Hoover Dam Bypass Bridge Financial Feasibility Study to determine viable funding sources for
the Hoover Dam Bypass (June 2000). The study assessed toll crossings and other financial
options. A toll facility would require legislative action and is not supported by ADOT or
NDOT, thus it is not considered viable or anticipated. The study recommended that
Arizona and Nevada should: 1) continue to pursue full federal funding, and
2) simultaneously pursue "debt backed by federal and by state funds" approaches.
SCO/CHAP-2.WPD/003672774 2-43
-------
CHAPTER 2 ALTERNATIVES
This page intentionally left blank.
2-44 SCO/CHAP-2.WPD/003672774
-------
CHAPTER 3

Affected Environment, Environmental

Consequences, and Measures to Minimize

Harm

Introduction

This chapter provides a description of the existing social, economic, and environmental
settings for the area affected by the three build alternatives and the No Build Alternative.
The affected environment is described for each resource of concern in the proposed project
area. The discussion contains data, information, issues, and values that have a bearing on
possible impacts, mitigation measures, and identification.of the Sugarloaf Mountain
alignment as the preferred alternative.

Probable beneficial and adverse social, economic, and environmental effects of alternatives
under consideration are described. The information provides a basis for evaluating the
comparative merits of the alternatives and for identifying the preferred alternative. Some
impacts to specific resources were evaluated for each build alternative and the No Build
Alternative, while others were evaluated regionally. Where data were available for each
alternative and effects differed, individual alternative analyses were performed. This
chapter also presents mitigation measures to reduce identified impacts to the preferred
alternative and others considered.

This EIS was prepared consistent with FHWA's Guidance for Preparing and Processing
Environmental and Section 4(f) Documents (FHWA Technical Advisory T 6640.8A, October 30,
1987). This guidance lists potentially significant impacts most commonly encountered by
highway projects and directs that these factors should be discussed for each reasonable
alternative where a potential for impact exists. Environmental and sotioeconomic factors
potentially impacted by the proposed project are analyzed in detail in this chapter. Factors
which were found to have no potential for project-related impacts and are not discussed in
this chapter are as follows:

Wetlands
Relocation Impacts
Joint Development
Wild and Scenic Rivers
Coastal Barriers
Coastal Zone Impacts

The following additional technical reports were prepared for the Hoover Dam Bypass DEIS,
and they are available through the Federal Highway Administration, Central Federal Lands
Highway Division (contact Dave Zanetell at 303/716-2157 for additional information):

Air Quality Analysis
Noise Analysis
Section 404 Jurisdictional Delineation Report
Visual Resources Analysis
Biological Assessment
Archaeological Resources Survey Report

SCO/CHAP3.WPD/003672775 3'1
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Historic Resources Survey Report
• American Indian Ethnographic Study

3.1 Air Quality

3.1.1 Affected Environment

National ambient air quality standards (NAAQS) have been established for several major
pollutants referred to as "criteria" pollutants. The NAAQS are two-tiered: primary—to
protect public health; and secondary—to prevent degradation to the environment
(e.g., impairing visibility, damaging vegetation and property). The six criteria pollutants
are:

Carbon monoxide (CO)
Particulate matter with diameters less than 10 microns (PM10)
Nitrogen dioxide (NO2)
Sulfur dioxide (SO2)
Ozone
Lead(Pb)

In addition, the U.S. Environmental Protection Agency (EPA) recently set new standards for
particulate matter with diameters less than 2.5 microns (PM2 5) and revised the ozone
standard. Both Nevada and Arizona have adopted the federal standards.

The Clark County Health District Air Pollution Control Division regulates air quality in
Clark County. The Arizona Department of Environmental Quality (ADEQ) regulates air
quality in Mohave County.

Because of the larger population density, Clark County has considerably more emissions
than Mohave County. Clark County also has several large coal-fired power plants, which
account for 93 percent of all SO2 emissions in Clark County. No large coal-consuming
sources exist in Mohave County; therefore, SO2 emissions are negligible.

Vehicle exhaust creates a significant amount of volatile organic compounds (VOCs),
nitrogen oxides (NOX), and CO emissions. Motor vehicle emissions (particularly CO) are
primary contributors to air pollution. CO is a colorless, odorless gas typically formed as a
result of incomplete combustion. Elevated concentrations typically occur during the winter
because vehicle engines operate less efficiently in cold weather. Concentrations tend to be
higher during stable atmospheric conditions when limited mixing and low wind speeds
tend to keep pollutants near the ground. They usually occur in the immediate vicinity of
congested roads and intersections where vehicles are idling.

Ozone is a pollutant formed through a complex series of temperature-dependent photo-
chemical reactions involving precursor pollutants such as NOX and VOCs, which are
emitted as vehicle exhaust. High ozone concentrations typically occur during multiday
periods of hot, sunny days accompanied by stagnant weather patterns. Under these
conditions, pollution from outside the region may be transported into the area,
compounding the problem. This makes ozone a regional-scale pollutant and can affect
rural areas outside the major metropolitan areas.

In addition to ozone formation, exhaust gases (NOX, hydrocarbons, and SO2) released into
the atmosphere can be converted to fine particulate matter through similar (and related)

3-2 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

chemical and photochemical reactions. Fossil-fuel combustion (resulting from motor
vehicles and industry) is the major source of gases in secondary particle formation. These
secondary particles are generally very small (PM2 5 or less) and are of concern because they
stay suspended longer and can go deeper into the lungs. In addition, fine particulate is a
major component of regional haze and visibility impairment. The formation of nitrates and
sulfates resulting from these reactions creates acid deposition (acid rain) downwind.

Fine particulate matter can also be directly emitted into the atmosphere. Sources of direct
particulate emissions include:

• Wind-blown dust from construction activities, unpaved roads, agriculture, and barren
lands

• Fine soot generated from residential wood-burning stoves, fireplaces, wildfire, and
brush/waste burning

• Fine soot and particulate from motor vehicle emissions and industrial sources

• Sand and gravel operations

• Off-road recreational vehicles

Because of the dry, hot conditions, this region is susceptible to high particulate (PM10)
concentrations, especially during construction. The Clark County Air Pollution Control
Division estimates that construction activity produces more than 40 percent of the PM10
emissions in the Las Vegas Valley.

The Las Vegas and Henderson urban area does not meet air quality standards
(nonattainment) for PM10 and CO. The southern edge of the nonattainment area is located
at Railroad Pass where U.S. 93 and U.S. 95 meet. All other areas in Clark County outside of
the Las Vegas Valley (Las Vegas, North Las Vegas, and the Henderson urban area) are in
attainment for all pollutants. The proposed project is located outside the nonattainment
area. Mohave County (Arizona) does meet air quality standards (attainment) for all
pollutants, except in Bullhead City, which is nonattainment for PM10 and is located in the
southwestern part of the County. Table 3-1 shows the attainment status for Clark and
Mohave counties.

Table 3-1
Attainment Status
Location Status
Clark County

Las Vegas/Henderson urban area Nonattainment for PM10 and CO
All other areas Attainment for all pollutants
Mohave County
Bullhead City Nonattainment for PM10
All other areas Attainment for all pollutants
Hoover Dam Area Attainment for all pollutants
SCO/CHAP3.WPD/003672775 3-3
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Because the project is located in an area that is meeting air quality standards and no
Statewide Improvement Program-related transportation control measures exist, the
conformity procedures of 23 CFR 770 do not apply to this project.

Vehicle exhaust is the primary source of project-related air pollution. Pollutants include
NOX, CO, fine particulate, hydrocarbons, and SO2. Table 3-2 shows existing traffic volumes
in the proposed project area.

Table 3-2
Existing Traffic Conditions
Location
West of Hoover Dam
At Hoover Dam
East of Hoover Dam
AADT
13,200
11,500
9,300
Peak Hour
1,188
1,035
837
LOS
E
F
E
Source: Appendix A, Traffic Analysis

Vehicle emissions were estimated using EPA-approved models. Table 3-3 shows estimated
emissions per vehicle mile traveled (VMT) as a function of speed for 1997.

Emissions of sulphur oxides (SOX) and PM are insensitive to vehicle speed. For CO and
hydrocarbons, the highest emissions occur at low vehicle speeds, are lowest at about 45 to
55 mph, and then peak again at higher speeds.

Table 3-3
Estimated 1997 Vehicle Emission Rates
Speed
(mph)
10
15
25
35
45
50
55
60
CO
82.86
60.80
40.13
29.55
23.97
22.87
23.00
37.96
Pollutant Emissions in g/VMT"
NOX Hydrocarbons SOX
3.35
3.11
2.98
3.02
3.15
3.42
3.97
4.58
7.84
5.81
3.94
3.02
2.52
2.40
2.39
2.83
0.114
0.114
0.114
0.114
0.114
0.114
0.114
0.114
PM
5.22
5.22
5.22
5.22
5.22
5.22
5.22
5.22
a grams per vehicle mile traveled

Using these emission factors, an estimate of the daily pollution burden around the project
site was calculated. A speed of 10 mph was assumed for an average LOS F traffic flow
condition, and 25 mph was assumed for a typical free-flow speed near the dam. Using the
project-burden relationship (the ratio between vehicle speeds, numbers of vehicles, and
emissions), the existing project burden was estimated as shown in Table 3-4.
3-4 SCO/9820800.WRD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-4
Existing Project Burden
Pollutant Emissions in Pounds per Day
CO NO* VOC SO, PM10
Existing Burden
6,890 442 669 17 759
Project Burden 1,257
Clark and Mohave 287,614
Counties Emissions
Fraction of Inventory 0.0044
Burden Emissions in Tons/Year
81 122 3
99,838 52,719 51,302
0.0008
0.0023
> 0.001
138

32,017

0.004
The existing Hoover Dam crossing, which is a very small segment of the regional roadway
system, contributes a small fraction of the total regional pollution inventory and has a
minor role in regional pollution impacts such as ozone and regional haze.

CO is considered a microscale pollutant and is usually evaluated for short-term 1-hour and
8-hour hot-spot impacts. For this study, CO impacts in the area immediately around
Hoover Dam were evaluated because of worker and visitor density. The dam roadway and
the 1,000-foot approaches on either side were included in the analysis. For this analysis, the
EPA-approved dispersion model for evaluating CO and particulate impacts from roadway
vehicles was used. Worst-case conditions under LOS F were evaluated. The maximum
1-hour CO impact was found to be 6.3 parts per million (ppm) without background. Rural
backgrounds ranged from 1 to 2 ppm, well below the standard of 35 ppm.

3.1.2 Environmental Consequences

3.1.2.1 Construction Impacts
Any of the build alternatives, including the preferred alternative, would generate dust
emissions during construction. Construction emissions vary from day to day and activity to
activity, with each activity having its own potential to release emissions. Construction
activities that can produce dust (PM10) emissions include rock blasting and handling,
vehicle and truck travel over unpaved roads, blowing wind over disturbed areas, and
tail-pipe exhaust being emitted from vehicles and equipment. Because of the variability in
timing and intensity of construction, estimating construction-phase pollutant emissions is
difficult. Furthermore, activities such as blasting do not have accepted and recognized
emission factors. Nevertheless, it is assumed that there will be adverse PM10 impacts.

Other pollutants (CO, NOX, VOC, and SOX) are primarily emitted from construction
equipment exhaust pipes. These pollutants are of less concern because construction
activities are generally short-term, spread over a wide area, and do not impede regional air
quality standards.

3.1.2.2 Operational Impacts
Daily pollutant emission estimates for the project alternatives are shown below in Table 3-5.
Under the No Build Alternative, pollutant emissions increase substantially as the number of
vehicles increase and the length of time at LOS F in the proposed project area increases.
SCO/CHAP3.WPD/003672775
3-5
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The three build alternatives, in contrast, enable lessened CO and VOC emissions as LOS in
the proposed project area is improved. In fact, year 2027 CO concentrations for each build
alternative are less than existing CO concentrations. With construction of any of the build
alternatives, CO emissions at the Hoover Dam roadway would be less: 6,439 pounds per
day in year 2027 compared to 6,890 pounds per day currently.

Table 3-5
Daily Emissions by Alternative
Pollutants in Pounds per Day
Scenario
Existing
CO
6,890
NOX
442
VOC
669
S02
17
PM
759
Year 2017
No Build
Build Alternatives8
11,182
5,120
677
691
1,177
628
32
32
1,712
1,712
Year 2027
No Build
Build Alternatives8
14,724
6,439
850
855
1,547
785
40
40
2,144
2,144
8 Build—Differences in air quality impacts between the build alternatives are negligible.
3.1.3 Measures to Minimize Harm

3.1.3.1 Construction Mitigation
The project will obtain and maintain all applicable permits pertaining to dust abatement
and blasting. Clark County requires dust control permits for such construction. For
Mohave County, the ADEQ stipulates that portable sources of air pollution (i.e., rock, sand,
gravel, and asphaltic concrete plants) will require an ADEQ permit. Reasonable steps will
be taken to prevent fugitive dust emissions 24 hours a day, seven days a week, during
project construction. Specific dust abatement measures (per Clark County Health District
dust control permit requirements, revised July 1,1997) include:

• Keeping all dirt access roads and staging areas watered
• Keeping dirt off paved roads by sweeping, scraping, or flushing with water
• Installing a gravel pad at least 30 feet wide by 50 feet long by 6 inches deep consisting of
1-inch- to 3-inch-thick material at truck exits to minimize dirt tracked out—if necessary,
washing down trucks leaving proposed project area

• Stabilizing disturbed areas by watering, revegetating, or applying dust suppressants
where no continuing development occurs within 30 days of the disturbance of that area

• Prohibiting open burning onsite without appropriate permits
• Stopping all operations, except watering trucks, during high-wind conditions that result
in dust emissions that leave the proposed project area, and applying appropriate
mitigation (e.g., soil stabilizers and wind breaks) to areas susceptible to high winds to
prevent further occurrences

• Limiting vehicle speeds to reduce dust emissions

3-6 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

3.1.3.2 Operational Mitigation
No mitigation measures exist for the operational phase of the project.

3.2 Noise

3.2.1 Affected Environment

A noise study was performed and a technical report was prepared to meet the requirements
of FHWA's Procedures for Abatement ofHighmy Traffic Noise and Construction Noise (23 CFR
772, April 1992) and the guidelines in FHWA Technical Advisory T6640.8A (Guidancefor
Preparing and Processing Environmental and Section 4(f) Documents, 1987).

All noise levels referred to in this report are stated as hourly equivalent sound pressure
levels (L^), which is the average noise energy level for a stated period of time (e.g., hourly),
in terms of decibels on the A-scale (dBA). Noise levels stated in dBA approximate the
response of the human ear by filtering out some noise in the low and high frequency ranges
that the ear does not detect well. The A-scale is used in most ordinances and standards.

Project traffic noise levels are evaluated against the traffic noise impact criteria established
by FHWA, NDOT, and ADOT. The FHWA noise level criterion for noise-sensitive land
uses, called Activity Category B sites (e.g., residences, churches, schools, recreational uses,
and similar areas), is considered exceeded when the exterior noise level approaches or
exceeds 67 dBA. The noise level criterion for extra-sensitive land uses, called Activity
Category A sites (i.e., lands where serenity and quiet are of extraordinary significance), is
an exterior noise level of 57 dBA. The federal criteria are based on peak-hour traffic noise
levels.
Table 3-6 shows the FHWA Design Level/Activity Relationship used to determine the noise
abatement criterion for specific land uses (e.g., residential and commercial). FHWA
considers a traffic noise impact to occur if predicted peak-hour traffic noise levels approach
or exceed the noise abatement criteria or substantially exceed existing levels. NDOT defines
"approach" as within 1 dBA of the noise abatement criteria; ADOT defines "approach" as
within 2 dBA of the noise abatement criteria. Therefore, in Nevada, the noise abatement
threshold is 66 dBA-L^ for Activity Category B, and 56 dBA-L^ for Activity Category A. In
Arizona, the noise abatement threshold is 65 dBA-L^ for Activity Category B and
55 dBA-L^ for Activity Category A. NDOT and ADOT both consider 15 dBA to be a
substantial increase. Mitigation measures are analyzed based on NDOT and ADOT's
policies.

Existing noise levels in the proposed project area were determined by field measurements at
five sites identified by the Project Management Team and by modeling existing peak-hour
traffic noise levels (see Tables 3-7 and 3-8). These sites were located to best represent the
primary sensitive receptors/human activity areas affected by the project. The actual
measurements served as verification of the modeling estimates at locations where vehicular
traffic was the dominant noise source. Noise levels from traffic for existing and future
conditions were calculated using the FHWA traffic noise prediction model (STAMINA
2.0/OPTIMA). Input to the model included traffic volume and vehicle speed data
generated for the project.
SCO/CHAP3.WPD/003672775 3-7
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-6
Federal Highway Administration Design Noise Level/Activity Relationships

Activity Design Noise Levels
Category (dBA)" L*, hourly
Description of Land Use Activity Category
Aa 57 (Exterior) Land tracts where serenity and quiet are of extraordinary significance
and which serve an important public need and where the preservation of
those qualities is essential if they are to continue to serve their intended
purpose. Such areas could include amphitheaters, parks or portions of
parks, open spaces, or historic districts that are dedicated or recognized
by appropriate local officiate.

B" 67 (Exterior) Picnic areas, recreation areas, playgrounds, active sports areas, and
parks not included in Category A; and residences, motels, hotels, public
meeting rooms, schools, churches, libraries, and hospitals.

C 72 (Exterior) Developed lands, properties, or activities not included in Categories A
and B above.

D — Undeveloped lands.

E 52 (Interior) Residences, motels, hotels, public meeting rooms, schools, churches,
libraries, hospitals, and auditoriums.

Source: 23 CFR Part 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise.
Federal Highway Administration, April 1992.
8 Parklands in Categories A and B Include all such lands (public or private) used as parks as well as those
public lands officially set aside or designated by a governmental agency as paries on the date of public
knowledge of the proposed highway project.
Table 3-7
Measured Noise Levels (dBA-LM)
Monitoring
Location
M1
M2
M3
M4
M5
Description
Lakeview Point
Boat Launch below Hoover
Dam
Nevada Intake Tower
Gold Strike Canyon Trail
Gold Strike Canyon Hot Springs
Measured
Noise Level
47
52
72
39
60
Dominant Noise Sources
Vehicle traffic on U.S. 93, small aircraft
overhead, birds
Water hitting shore and booms below
Hoover Dam
Vehicle traffic on U.S. 93
Wind through bushes, birds, small
aircraft overhead
Rushing water
Construction noise levels were also estimated using the methods described in Highway
Construction Noise: Measurement, Prediction, and Mitigation (1977). However, these estimates
should be considered less precise than the traffic noise level calculations because, at this
preliminary project stage, assumptions must be made about the construction equipment to
be used, location and duration of use, and noise characteristics of each piece of equipment.
3-8
SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM
Table 3-8
Existing Peak-Hour Noise Levels
Receptor Location Activity Category Impact Criterion Modeled Noise Level
R1/M1
R2/M2
R3/M3
R4/M4
R5/M5
B
B
B
B
B
67
67
67
67
67
50
52"
73b
39"
60"
8 Noise levels at this receptor location are dominated by sources other than vehicle traffic. Therefore, existing
noise levels are based on measured noise levels rather than modeled.
" Noise levels approach or exceed the FHWA noise abatement criterion.

3.2.1.1 Noise Level Measurements
Existing noise levels were measured at 5 monitoring (M) sites. Monitoring location Ml is at
Lakeview Point, an overlook to Lake Mead (see Figure 3-1). Monitoring location M2 is at
the boat launch below Hoover Dam. This area has restricted access, with groups being
allowed access twice daily to launch canoe trips. Monitoring location M3 is on Hoover
Dam on the sidewalk by the Nevada Intake Tower. Monitoring location M4 is on the Gold
Strike Canyon Trail, and monitoring location M5 is located at the Gold Strike Canyon Hot
Springs. Monitoring locations Ml through M5 are all recreational uses (Activity Category
B), but are not considered areas where quiet is of significant importance. Table 3-7 shows
the measured noise levels at each site.

3.2.1.2 Model Verification
At monitoring locations Ml and M3, which have vehicular traffic as a dominant noise
source, noise levels were also estimated by using the FHWA highway noise prediction
model. The model uses data on traffic volumes, vehicle mix, speed, vehicle noise emission
levels, and roadway geometry to predict traffic-generated noise levels at chosen receptors.
To test agreement between calculated and measured noise levels, traffic volumes counted
during the monitoring period are used in the model. These levels are then compared with
the measured noise levels. For this project, the modeled and measured results agreed
within 3 dBA. A traffic noise level variation of 3 dBA or less is considered barely
perceptible to imperceptible. Therefore, an agreement between measured and modeled
traffic noise levels resulting in 3 dBA or less is acceptable.

3.2.1.3 Existing Noise Levels
Five computer modeling receptor (R) locations, corresponding to the five monitoring (M)
locations, were selected for use in predicting noise levels in the proposed project area. To
calculate existing peak-hour noise levels, traffic data generated for the project were used in
the verified noise model. Existing peak-hour noise levels for the 5 receptors are
summarized in Table 3-8. FHWA criteria are shown for comparison.
SCO/CHAP3.WPD/003672775 3-9
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.2.2 Environmental Consequences

3.2.2.1 Construction Impacts

Promontory Point Alternative. Construction impacts under the Promontory Point Alternative
are the same as those discussed below under the preferred alternative.

Sugarloaf Mountain Alternative (Preferred Alternative). Heavy equipment used during
construction would have short-term noise impacts on the recreational areas along the
proposed alignment. Receptor locations R1/M1 and R3/M3 are the nearest sensitive sites
to construction activity along the Promontory Point Alternative (see Figure 3-1). Each is
approximately 1,000 feet from the alternative. Table 3-9 shows estimated noise levels for
construction activities at 50 and 1,000 feet.

Blasting would also occur along the alignment during construction. Blasting would be
short-term and would occur only when normal excavating methods could not remove solid
rock formations. Noise and vibration levels resulting from blasting are dependent on size,
timing, and number of blasts; the blast area; transmitting medium; and distance to the
receptor.

Gold Strike Canyon Alternative. Heavy equipment used during construction would have
short-term noise impacts on the Gold Strike Canyon recreational areas represented by
R4/M4 and R5/M5. Receptor locations R4/M4 and R5/M5 are approximately 50 feet and
1,000 feet from the alternative, respectively (see Figure 3-1). Table 3-9 shows estimated
noise levels for different construction activities at 50 feet and 1,000 feet.

Table 3-9
Estimated Peak Construction Noise Levels (dBA)
Construction Phase Loudest Equipment Noise Level at 50 and 1,000 feet
Clearing and grubbing
Earthwork
Foundation
Superstructure
Base Preparation
Paving
Bulldozer, backhoe
Scraper, bulldozer
Backhoe, loader
Crane, loader
Trucks, bulldozer
Paver, trucks
89/63
91/65
88/62
89/63
91/65
92/66
Source: Highway Construction Noise: Measurement, Prediction, and Mitigation. U.S. Department of
Transportation, 1977.

Blasting would occur under the Gold Strike Canyon Alternative as discussed under the
Promontory Point Alternative.

No Build Alternative. Because no construction would occur under the No Build Alternative,
no construction impacts would occur.

3.2.2.2 Operational Impacts
Table 3-10 shows future (year 2017) peak-hour noise levels for the build alternatives and the
No Build Alternative. The results show that future predicted traffic noise levels will
increase from 1 dBA to 26 dBA above existing ambient levels. However, comparing future
noise levels for the three build alternatives with the No Build Alternative indicates that
levels will range from a 3 dBA decrease to a 26 dBA increase with the U.S. 93 bypass
alternatives. The results also show that traffic-generated noise from the proposed project
3-10 SCO/9820800.WPD/003672775
-------
I,/,'
RECEPTOR SITE AT
NEVADA INTAKE TOWER
R3/M3
RECEPTOR SITE flT *r* •*"""
LAKEVIEW POINT OVERLOOK •
RHM1
HACIENDA
OTEL
RECEPTOR SITE AT I
RAFT LAUNCHING AREA 4
R2/M2
BEGIN
PROJECT
RECEPTOR SITE AT
GOLD STRIKE CANYON TRAIL
R4/M4
. A RECEPTOR SrTE AT
GOLO STRIKE CANYON
Stf i*»HG SPRINGS AREA
APPROXIMATE LIMITS
OF NOISE BARRIERS
LEGEND
PROMONTORY POINT ALTERNATIVE

SUQARLOAF MOUNTAIN ALTERNATIVE

QOLD STRIKE CANYON ALTERNATIVE
END
PROJECT
1000 2000 FEET
SCALE IS APPROXIMATE

142883.15.05 2439.12C fh 3/00
»»»
U.S. 93

NOISE RECEPTOR
FIGURE 3-1
NOISE RECEPTOR SITES AND
RECOMMENDED MITIGATION
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

3-11
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-12 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

results in the federal and state noise abatement criteria being exceeded at receptors R3/M3
and R4/M4, the Nevada intake tower and Gold Strike Canyon Trail, respectively. For
R3/M3, it should be noted that the project results in only a 1 dBA increase over existing and
3 dBA under the projected no build noise level. Federal and state noise criteria will not be
exceeded at R1/M1, representing the Lakeview Point Overlook and planned Historic
Railroad Trail, R2/M2 or R5/M5, which represent the raft launching area and the Gold
Strike hot springs, respectively.

Based on a study completed by FHWA, the noise produced by a truck traveling at 20 mph is
as loud as 85 cars traveling at 20 mph (FHWA, August 2000). Therefore, although modeling
shows no perceptible change in future peak-hour average noise levels, high noise emissions
from individual trucks crossing the dam will be eliminated, thereby improving the noise
environment for HDNHL visitors.

Table 3-10
Receptor
Location
R1/M1
R2/M2
R3/M3
R4/M4
R5/M5
Impact
Criterion
67
67
67
67
67
Existing
50
52"
73"
39"
60"
Promontory
Point
56
52"
74"
42
60"
Sugarioaf
Mountain
56
57
74"
42"
60"
Gold Strike
Canyon
51
52"
74b
65C
60"
No Build
54
52"
77b
39"
60"
8 Noise levels at this receptor location are dominated by sources other than vehicular traffic. Therefore,
noise levels are based on measured noise levels rather than on modeled.
* Noise levels approach or exceed the FHWA noise abatement criterion.
c Noise level represents a substantial exceedance of existing levels (i.e., greater than 15 dBA).
Gold Strike Canyon Alternative. Noise levels at location R3/M3 would exceed the 67
criterion because of traffic along U.S. 93. Noise levels at location R4/M4 would increase to
65 dBA-L^ with the addition of the U.S. 93 bypass. This level would not exceed the
67 dB A-L^ threshold for Category B land uses, but it would constitute a substantial increase
(> 15 dBA) under FHWA, NDOT, and ADOT noise abatement policies.1
No Build Alternative. Noise levels at location R3/M3 would further exceed the 67
criterion because of projected increased future traffic volumes on U.S. 93. The projected
future noise levels at location R3/M3 would actually be higher because through-trips by
lrThe Nevada Department of Transportation defines the noise abatement criterion as 1 dBA below the
FHWA criterion, or 66 dBA.

SCQ/CHAP3.WPD/003672775 3-13
Promontory Point Alternative. Noise levels at location R3/M3 would exceed the 67
criterion because of traffic along U.S. 93. No noticeable noise impacts would occur as a
result of U.S. 93 bypass operations.

Sugarioaf Mountain Alternative (Preferred Alternative). Noise levels at location R3/M3 would |
exceed the 67 dBA-L^ criterion because of traffic along U.S. 93. No noticeable noise impacts
would occur as a result of U.S. 93 bypass operations.
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

automobiles and trucks would not be diverted off the dam crossing onto the new bridge
alternatives.

3.2.3 Measures to Minimize Harm

3.2.3.1 Construction Mitigation

Promontory Point Alternative. Construction mitigation measures for the Promontory Point
Alternative would be the same as those discussed below for the preferred alternative.

| Sugarloaf Mountain Alternative (Preferred Alternative). To reduce construction noise levels,
the following measures will be implemented:

• Ensure that all engine-powered equipment has mufflers installed according to the
manufacturer's specifications

• Require all equipment to comply with applicable equipment noise standards

If specific noise complaints are received during construction, remedial measures will be
taken by the resident engineer. These measures could include the following:

• Locate stationary construction equipment as far from nearby noise sensitive properties
as possible

• Shut off idling equipment

• Reschedule construction operations to avoid periods of noise annoyance, as determined
through consultation with NFS and Reclamation and defined in special provisions

• Notify nearby affected parties whenever extremely noisy work will be occurring

• Install temporary or portable acoustic barriers around stationary construction noise
sources

Short-term noise increases from blasting operations may be addressed by the following
mitigation measures:

• Publicize the blasting schedule through the local media

• Time blasts so that shock waves created by blasts dissipate or cancel shock waves
created by subsequent blasts

Gold Strike Canyon Alternative. Construction mitigation measures for the Gold Strike
Canyon Alternative would be the same as those discussed above for the preferred
alternative; however, hikers would be excluded along the canyon trail from U.S. 93 to the
hot springs for a period of 5 to 6 years (see Chapter 6, Section 4(f) Evaluation).

3.2.3.2 Operational Mitigation
Traffic noise impacts can be mitigated by using several available methods. Available traffic
noise abatement measures include traffic management, highway design, and construction
of noise barriers.

Traffic management measures include modifying speed limits and restricting or prohibiting
truck traffic. Trucks are louder than cars; therefore, restricting their use on project
roadways would reduce noise levels at nearby sensitive receptors. However, as U.S. 93 is

3-14 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

projected to be a major NAFTA truck route, predicted year 2017 traffic volumes used for
this noise analysis assume a fairly high (18 percent) level of truck traffic. Reduction of
traffic speeds would also result in lowered traffic noise levels. However, restricting the
types of vehicles or reducing vehicle speeds would conflict with the purpose of this project,
which is to decrease congestion and increase safety on Hoover Dam and improve regional
traffic flow.
Constructing noise barriers between roadways and affected receptors reduces noise levels
by physically blocking the transmission of traffic-generated noise. Barriers can be
constructed as walls or earthen berms. As a general guideline, barriers should be high
enough to break the line-of-sight between the noise source and the receptor. Barriers must
also be long enough to prevent significant flanking of noise around the ends of the barrier.
Openings in barriers, such as for driveways, can significantly reduce barrier effectiveness.
Earthen berms require more right-of-way man walls and are usually constructed with a
3-to-l slope. Because the terrain is very steep along the proposed project area roadways,
which will have a high percentage of steep cuts, fills, and structures, using earthen berms
for noise mitigation may not be reasonable. Walls can be constructed using concrete, wood,
or metal.

Promontory Point Alternative. No noise impacts are expected as a result of the Promontory
Point Alternative; therefore, no noise mitigation would be required.

Sugarloaf Mountain Alternative (Preferred Alternative). No noise impacts are expected as a
result of the Sugarloaf Mountain Alternative; therefore, no noise mitigation would be
required.

Gold Strike Canyon Alternative. Noise receptor location R4/M4 would be impacted under
the Gold Strike Canyon Alternative due to a substantial exceedance of existing noise levels.
Table 3-11 shows the effects of noise barriers constructed along the U.S. 93 bypass in the
vicinity of location R4/M4. Figure 3-1 shows the approximate limits of the noise barriers.

Table 3-11 shows that noise barriers, located on the outside shoulder of the roadway on the
trail side, could reduce noise levels at R4/M4 to 59 dBA-L^ under the Gold Strike Canyon
Alternative. Noise levels would continue to substantially exceed existing levels (by
20 dBA), Although the noise impact would not be completely mitigated, an insertion loss of
up to 6 dBA would be possible with the addition of noise barriers.

Table 3-11
Gold Strike Canyon Alternative
Receiver
Location
R4/M4
Build, No
Mitigation
65
8-Foot
Barrier*
59
10-Foot
Barrier
59
12-Foot
Barrier
59
14-Foot
Barrier
59
16-Foot
Barrier
59
a Minimum barrier height required to break the line-of-sight between an 11.5-foot-truck exhaust stack and the
noise receptor.
SCO/CHAP3.WPD/003672775 3"15
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.3 Biology

3.3.1 Affected Environment

The proposed project area consists of the Black Canyon of the Colorado River where it
crosses the eastern Mojave Desert. The Black Mountains to the east and the El Dorado
Mountains to the west dominate the area's topography. These ranges are part of the Basin
and Range Geologic Province, with numerous isolated mountain ranges running north to
south throughout the Great Basin.

The Blade Canyon has winter habitat for bald eagles. Portions of the proposed project area
have been previously disturbed by human-made developments, including Hoover Dam,
Lake Mead, U.S. 93, electric transmission line towers, construction spoil sites, maintenance
facilities, and access roads. Figure 3-2 shows the locations of sensitive biological resources
in the proposed project area.

3.3.1.1 Terrestrial Vegetation and Wildlife Communities
Plant communities and associated wildlife in the proposed project area are typical of the
Eastern Mojave Desert. Within areas adjacent to the LMNRA, about 463 vertebrate animals
are known to occur (Niles et al., 1977). The checklist of vascular plants for the LMNRA is at
800 specific and intraspecific taxa (Holland et al., 1979). This species list is maintained by
NPS. Vegetation-type classifications (Brown, 1982) and typical landscapes, plant
communities, and wildlife habitats found in the proposed project area are described below.

Creosote-Bursage Plant Community. Creosote-bursage is the dominant vegetation found in
the proposed project area, comprising about 70 percent of the LMNRA (NPS, 1986) and
most of the Mojave Desert below the 3,000-foot elevation. Dominant plant species include
creosote bush, white bursage, sweetbush, white ratany, brittlebush, indigo bush, and
Mojave yucca. Associated cacti include single barrel cactus, silver cholla, and beavertail.
Common perennial plant species include globemallow and desert trumpet.

Desert Wash Community. Desert washes that support the desert wash community provide
relatively higher soil moisture than the creosote-bursage plant community. Within the
proposed project area, this community is limited to the bottom of a few narrow drainages
found in Gold Strike Canyon. Species composition is similar to the creosote-bursage plant
community, with the addition of catclaw acacia, and less occasionally, honey mesquite and
desert willow. This plant community has a more complex vegetative structure than the
surrounding creosote-bursage plant community, which contributes to more abundant and
diverse wildlife. More bird species are found in desert washes than in the surrounding
creosote-bursage plant community.

Seep Wetlands and Riparian Areas. A concentration of active springs and seeps occurs on
both sides of the Colorado River between Hoover Dam and Willow Beach and in some side
canyons including Gold Strike Canyon. Many of these springs and seeps are geothermal,
highly mineralized, and support specialized aquatic plants and invertebrates. Riparian and
wetland plant species associated with these areas include maidenhair fern, bushy
beardgrass, sedges, cattails, salt grass, arrowweed, and salt cedar. The natural riparian
vegetation in Gold Strike Canyon has been disturbed by recreational use. The large wash in
Arizona immediately south of the Gold Strike Canyon Alternative supports a dense stand of
saltcedar and other riparian vegetation. Riverbanks along the Colorado River immediately

3-16 SCO/9820800. WPD/003672775
-------
LEGEND
C60 1300 FEET
— PROMONTORY POINT ALTERNATIVE
SUOARLOAF MOUNTAIN ALTERNATIVE
- - SOLD STRIKE CANYON ALTERNATIVE
— U.S. 93
DRAINAGE
•>:••-•- 8HEEPWKTERINGAREA6
BOUNDARY OP SHEEP LAMBING AND NURSERY HABITAT
„*„,„ fc. MAJOR SHEEP MOVEMENT CORRIDOR
SCM.E IS APPROXIMATE
MMI tics »a.u« m 7m
FIGURE 3-2
LOCATION OF SENSITIVE
BIOLOGICAL RESOURCES
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-18 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

downstream of Hoover Dam support only widely scattered stands of sparse riparian plants,
of which saltcedar is the predominant shrub species.

Waters Of the United States. Well-defined drainage paths generally exist throughout most of
the proposed project area (see Figures 3-2 and 3-3). Approximately 27 small, natural
intermittent washes occur along the proposed alignments that drain relatively small
watersheds (designated as A through Z, AA, GS, and PP on Figures 3-2 and 3-3). These are
narrow washes (1 to 3 feet wide) that drain a local watershed of approximately 2 acres.
Two larger, intermittent desert washes also occur in the study area. These washes are
broader (from a few feet to over 20 feet wide) and drain watersheds that cover more than
50 acres. One of the larger washes (Gold Strike Canyon Wash) runs along the Gold Strike
Canyon Alternative (GS on Figure 3-3). The lower end of the wash has perennial flow. Hot
springs occur before the terminus at the Colorado River, producing year-round runoff into
the river. A medium-sized, unnamed drainage runs in a north-south direction west of
U.S. 93 in Arizona, intersecting each of the build alternatives (PP on Figure 3-3). The major
perennial water source in the area is the Colorado River. As shown on Figure 3-3, the river
(Lake Mead) is approximately 1,000 feet wide upstream of Hoover Dam and approximately
400 feet wide downstream of Hoover Dam. The width of the river varies both daily and
seasonally depending on the amount of rainfall and the amount of water released by
Hoover Dam to Lake Mohave.

A field delineation was performed in March 1998 (see Figure 3-3) to determine the extent of
waters of the United States under the jurisdiction of the U.S. Army Corps of Engineers. All
of the desert washes shown on Figure 3-3 and the Colorado River are considered waters of
the United States. No jurisdictional wetlands were identified in the proposed project area.

Cliff Habitat. Extensive cliff habitat exists immediately adjacent to the Colorado River and in
Gold Strike Canyon. Many of these areas are composed of basalt and andesite, which have
the necessary cracks, ledges, and caverns to provide cover for many wildlife species. These
volcanic rocks resist erosion, thus providing relatively stable habitat. Plants adapted for
steep cliffs in Black Canyon include cloak fern, pungent brickellia, desert tobacco, pygmy
cedar, and desert rock nettle. Cliffs in Black Canyon support reptiles, birds, and mammals.
Various raptor species use upward-flowing warm air currents associated with the higher
cliffs. Cliff habitat in arid landscapes within 0.25 mile of water has an especially high
wildlife value (Maser et al., 1979).

Examples of wildlife species found in the cliff habitat of Black Canyon include collared
lizard, chuckwalla, peregrine falcon, bald and golden eagle, great horned owl,
white-throated swift, common raven, canyon wren, several bat species, and desert bighorn
sheep. A colony of double-crested cormorants has nested recently on the cliffs on the
Nevada side of the canyon about 100 yards downstream of Hoover Dam.

3.3.1.2 Aquatic Communities
Colorado River. After Hoover Dam was built, the portion of the Colorado River
downstream of the dam changed from a warm, silt-laden river to a cold-water river system.
Thus, native warm-water fish, such as the Colorado River squawfish, humpback and
bonytail chub, and razorback sucker have been affected by introduced cold-water species.
The area downstream of Hoover Dam has subsequently become a popular trout fishery.
The Colorado River has been stocked with rainbow trout to maintain the fishery because
natural reproduction rates are low or nonexistent.
SCO/CHAPS. WPD/003672775 3-19
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The Colorado River supports birds during migration and in winter. Yearlong resident
waterbird species include the pied-billed grebe, double-crested cormorant, ruddy duck,
common gallinule, and American coot (Blake, 1978).

Lake Mead. The LMNRA, although seemingly barren, contains a surprising variety of plants
and animals, some of which are found nowhere else in the world. This reservoir, described
as a deep, subtropical, moderately productive desert impoundment, supports a valuable
sport fishery (Baker et al., 1977). Fish species occurring in Lake Mead are striped and
largemouth bass, channel catfish, bluegill, and black crappie (Listen and Grabowski, 1988).

3.3.1.3 Wildlife Resources
The proposed project area supports wildlife characteristic of the eastern Mqjave Desert.
Biological diversity varies according to topography, plant community, proximity to water,
soil type, and season, A literature search and field survey revealed 64 mammal species,
313 bird species, and 46 amphibian and reptile species occurring in the LMNRA (Niles et
al., 1997).

The most abundant mammals in the proposed project area are cactus mice and Merriam
kangaroo rats. Desert kangaroo rats and desert pocket mice are relatively uncommon and
are restricted to areas with sandy soil, such as desert washes. Species associated with rocky
habitats include the wood rat, rock pocket mouse, and rock squirrel. Species such as the
black-tailed hare, desert cottontail, and southern grasshopper mouse also have widespread
distribution in the proposed project area.

The most widespread and numerous predators in the proposed project area are the coyote,
gray fox, and several species of raptors (birds of prey). Mountain lion and bobcat are less
common and are associated with cliff habitat, dependent on availability of prey.

The proposed project area supports diverse and abundant reptile populations. According
to NFS, common species include zebra-tailed, long-tailed brush, desert spiny, and western
whiptail lizards, and western diamondback and speckled rattlesnakes.

Birds are the most diverse and abundant class of vertebrate animals found in the proposed
project area. The greatest number of birds are associated with major desert washes. Typical
breeding birds found in the desert washes include Gambel's quail, mourning dove,
ash-throated flycatcher, verdin, and black-tailed gnatcatcher. Breeding birds found in the
creosote-bursage plant community include black-throated sparrow and cactus wren.
Numerous migratory birds (including Brewer's sparrow, western flycatcher, and species of
warblers) move through the proposed project area. Wintering birds include phainopepla,
horned lark, and ruby-crowned kinglet.

Special-status species are protected pursuant to federal and state laws. These include those
species listed as threatened and endangered and those proposed for listing as threatened
and endangered. Although candidate species (federal) and species of concern (federal and
state) are not currently protected under federal or state laws, they are also considered
special-status species in this analysis, since during the project these species may be
upgraded to threatened or endangered status. These special-status species include:
3-20 SCO/9820800.WPD/003672775
-------
fij
1
P 93
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-22 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Wildlife and plant species listed or proposed for listing as threatened or endangered
pursuant to the federal Endangered Species Act (50 CFR 17.11 for wildlife, 50 CFR 17.12
for plants; and various notices in the Federal Register for proposed species)

• Wildlife and plant species that are candidates for listing as threatened or endangered
pursuant to the federal Endangered Species Act (50 CFR 17, February 28,1996) (USFWS
1997a,b)

• Species listed by the State of Arizona as threatened or endangered

• Wildlife species identified by AGFD as a species of concern (wildlife species that do not
have state or federal status but may still be threatened with extinction)

• Species listed by the State of Nevada as protected (Nevada Administrative Code,
Section 503.001-XX); and wildlife species identified by the Nevada Division of Wildlife
(NDOW) as a species of concern (wildlife species without state or federal status, but
which may be threatened with extinction)

Table 3-12 lists federal special-status species that may occur in the proposed project area,
their status, and the likelihood of their presence there. State special-status species (Nevada
and Arizona) potentially occurring in the proposed project area are also included in
Table 3-12.
Table 3-12
Special-status Vegetation and Wildlife Species Potentially Occurring in the Proposed Project Area and
Likelihood of Occurrence
Common Name Scientific Name
Federal/State
Status
Likelihood of Occurrence
in Proposed Project Area
Plants
Las Vegas bear
paw poppy

Bicolored
penstemon
Arctomecon
califomica

Penstemon bteolor
ssp. roseus
FSC/NP& ASC
FSC/NP & ASC
Fish
Bonytail chub Gila elegans
FE/NP & ASC
Razorback sucker Xyrauchen texanus FE/NP & ASC
Devil's hole
pupfish
Cyprinodon diabolis FE/NP
The Las Vegas bear paw poppy occurs in the
LMNRA, but has not been observed within the
proposed project area.
Bicolored penstemon occurs in wash gravels or
disturbed roadsides at elevations from 1,950 to
5,500 feet. It occurs in the LMNRA, but has not
been observed within the proposed project area.

The lack of suitable habitat near Hoover Dam and
cold water temperatures prevent the area from
supporting a viable population.
Unsuitable habitat and non-native predatory fish
prevent reproduction, recruitment, or the occurrence
of viable population in the river directly downstream
of Hoover Dam (Reclamation, 1992). Some
individual adult razorback suckers inhabit the Black
Canyon area of the river.
Devil's hole pupfish are not present at Hoover Dam.
A refugium (fish stocking tank) near the raft put-in is
being restored to repopulate pupfish in the area.
SCO/CHAP3.WPD/003672775
3-23
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-12
Special-status Vegetation and Wildlife Species Potentially Occurring in the Proposed Project Area and
Likelihood of Occurrence
Common Name Scientific Name
Federal/State
Status
Likelihood of Occurrence
in Proposed Project Area
Amphibians
Relict leopard frog Rana onca
/NP & ASC This species has been found in springs downstream
of Hoover Dam and in springs on the Overton Arm of
Lake Mead (USFWS, 1997b). Surveys conducted by
NPS In April and May 1996 at Sugarloaf Spring and
Gold Strike Canyon hot spring did not find Rana
onca at either drainage (Bill Burke, NPS, June 5,
1998 memorandum report).
Reptiles

Desert tortoise
(Mojave
population)
Desert tortoise
(Sonoran
population)
Chuckwalla
| Banded gila
monster
Birds
| Peregrine falcon
Gopherus agassizii FT/NP
Gopherus agassizii FSC/ASC
Sauromalus obesus FSC/
Heloderma
suspectum cinctum
Falco peregrinus
anatum
Bald eagle
Haliaeetus
leucocephalus
Low-density tortoise habitat (supporting fewer than
40 tortoises per square mile) was found throughout
the proposed project area. The area was
determined to be marginal habitat because of the
large amount of rocky terrain and disturbance to the
more suitable habitat. The area supports a few
desert tortoises of both Mojave and Sonoran
populations in Nevada and Arizona, respectively.

This species is found in rocky creosote bush habitat
along the three buiid alternatives, especially in talus
at the base of cliffs.
FSC/NP & ASC This species occurs in the project area. Population
is at an unknown density.
FE/NP & ASC This species is usually found in areas near
permanent water with nearby cliffs.

Five breeding territories in Black Canyon, 1 mile
upstream of Hoover Dam and 14 miles downstream,
were identified by the AGFD in 1990. It is likely that
the peregrine falcon population in Black Canyon has
breeding areas every 3 miles along the river.
FE/NP & ASC A wintering bald eagle population exists, fluctuating
between 14 and 24 birds in the LMNRA. The
proposed project area contains suitable wintering
habitat. No eagles were observed at the three build
alternative bridge sites during mid-winter from 1981
through 1991. During 1991 through 1998,26 bald
eagles were observed by the NPS over a 24-mile
stretch of Black Canyon, from Hoover Dam to El
Dorado Canyon. Most of these sightings occurred
during 1996 (12) and 1998 (11). Not more than one
or two eagles were observed within 3 miles of the
proposed bridge sites.
3-24
SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-12
Special-status Vegetation and Wildlife Species Potentially Occurring in the Proposed Project Area and
Likelihood of Occurrence
Common Name Scientific Name
Federal/State
Status
Likelihood of Occurrence
in Proposed Project Area
Southwestern Empidonax trailii
willow flycatcher extimus
FE/NP&ASC
Mammals
Spotted bat
Euderma
maculatum
FSC/NP & ASC
Yuma myotis bat Myotis yumanensis FSC/ASC
Myotis clliolabrum FSC/

Fringed myotis bat Myotis thysanodes FSC/ASC
Small-footed
myotis bat
Long-legged
myotis bat
Myotis volans
Big free-tailed bat Nyctinomops
macrotis
Desert bighorn
sheep
Ovis canidensis
nelson!
FSC/ASC

FSC/ASC

/IMP
Yuma puma Felis concolor /ASC
(mountain lion) browni
In 1997, nesting pairs of southwestern willow
flycatchers were documented along the Colorado
River at least 40 miles from the proposed project
area (Reclamation, 1998). The desert wash/ riparian
areas that would be affected by the three build
alternatives have no potential to be used by
breeding southwestern willow flycatchers.
Bat surveys were conducted by NPS in April and
May 1998 to inventory the species present within the
build alternative corridors. Three locations were
surveyed. The surveyed sites, chosen for their
proximity to water and vegetation, were Sugarloaf
Canyon, Arizona; Gold Strike Canyon, Nevada; and
the Hoover Dam sewer lagoons, Arizona. Mist
netting proved unsuccessful in all three locations due
to a variety of factors, including weather conditions,
time of year, and low densities and numbers of bats
present. Echolocation calls were recorded using the
"Anabat II" system, and species identification was
obtained after analysis of the calls. Identification has
been confirmed by Biologist Mike O'Farrell, an
authority in the analysis of Anabat recordings. High
densities of bats were not found at any of the survey
locations (Bill Burke, NPS, June 5,1998
memorandum report).
The combination of the rugged topography of Black
Canyon and the water sources along the Colorado
River provides exceptional, high-quality desert
bighorn sheep habitat.
The historic distribution of the mountain lion includes
the mountainous terrain on both sides of the lower
Colorado River from Lake Mead to the Gulf of
California. Predation on desert bighorn sheep by
mountain lions in the proposed project area has
been documented (Cunningham and Hanna, 1992;
Cooperative National Park Resources Studies Unit,
1990).
Notes
Source: USFWS, 1997a; The Wildlife Society, 1996

Federal Status Codes:
FE—Federally-listed endangered
FT—Federally-listed threatened
FSC—Federal species of concern. These species were formerly known as "Category 2 Candidates." USFWS
does not have enough scientific information to support a listing proposal for these species. The USFWS is still
concerned about these species and continues to gather information about them.

State Status Codes:
NP—State of Nevada protected (either endangered, threatened, or species of concern)
AT—State of Arizona threatened
ASC—Arizona species of concern
SCO/CHAP3.WPD/003672775
3-25
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.3.2 Environmental Consequences

Construction and maintenance activities have disturbed much of the habitat in the
proposed project area. Between 20 and 70 percent of the land within the proposed highway
right-of-way corridors show signs of past disturbance resulting from dam construction and
construction of access roads, electric transmission towers and switchyards, and building
sites. In many areas, the land has been scraped down to mineral soil or covered with spoil
material. However, wildlife does occur in the altered/disturbed areas, which have minimal
human presence and recent disturbance.

Habitats along the three build alternatives were evaluated to determine whether
disturbance has occurred. Table 3-13 summarizes those results. Impacts from the No Build
Alternative are summarized in Tables 3-13 and 3-14.

3.3.2.1 Construction Impacts
Impacts to biological resources normally occur during construction. Construction impacts
identified below were determined based on an average construction right-of-way of
300 feet.

Aside from Lake Mead and the Colorado River, water sources valuable to wildlife are scarce
in the proposed project area. As Figure 3-2 shows, each of the build alternatives could
affect at least one water source. The Promontory Point Alternative could affect a sump field
located near the Reclamation warehouse. The Sugarloaf Mountain Alternative would affect
sewage disposal ponds, used as a wildlife watering source, and warehouse water sources.
The Gold Strike Canyon Alternative would affect water flow through the lower course of
the canyon. According to NDOW, this is a very important perennial water source to
wildlife, specifically bighorn sheep. Noise disturbance during construction could affect
wildlife using the Colorado River near the hot springs south of the Gold Strike Canyon
Alternative. Adverse impacts, as a result of construction, will not occur with the No Build
Alternative. This alternative assumes continuation of existing conditions.

Impact of Construction on Common and Special-Status Plant Species. Because no
special-status plant species occur along the three build alternatives, no impacts to such
species would occur as a result of construction of any of the build alternatives.
Construction impacts from equipment storage, parking, and staging areas would, however,
result in disturbing several common plant species within the construction zone.
Construction of the proposed alternative, including the construction zone itself, would
result in the removal of approximately 122 to 143 acres (depending on the alternative) of
creosote-bursage habitat (see Table 3-13).

Table 3-13
Comparison of Impacts to General Terrestrial Communities from All Alternatives
(Colorado River Bridge - Hoover Dam)
Alternative
Impact
Promontory Point Sugarloaf Mountain Gold Strike Canyon No Build
Total land disturbance8
Impact from soil
3.55 miles
134 acres
5 acres
3.35 miles
122 acres
Oacre
3.30 miles
143 acres
23 acres
No change
No change
disposal sites
3-26
SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Table 3-13
Comparison of Impacts to General Terrestrial Communities from All Alternatives
(Colorado River Bridge - Hoover Dam)
Impact
Habitat previously
undisturbed"
Desert wash habitat loss
Seep wetlands and
riparian loss
Cliff habitat loss

Promontory Point
29 acres
22 percent
0.6 acre
No impact
About 4.2 acres
affected by road
construction
Alternative
Sugarloaf Mountain
26 acres
21 percent
0.3 acre
No impact
About 1 .4 acres affected
by road construction

Gold Strike Canyon
100 acres
70 percent
1 1 acres
No impact
About 12.7 acres
affected by road
construction

No Build
No change
No change
No change
No change
General habitat
concerns

Other miscellaneous
impacts
Slight disturbances
at bridge site

Habitat quality is
low due to existing
disturbances

Movement of exist-
ing transmission
lines and towers
would result in
minor land
disturbance
Slight disturbances at
bridge site

Habitat quality is low
due to existing
disturbances

Movement of existing
transmission lines and
towers would result in
minor land disturbance
Slight disturbances
at bridge site

Relatively high
quality due to area's
isolation

No impact
No change
No change
• Based on average construction of 300-foot right-of-way. Most vegetation loss is creosote-bursage habitat.
About 50 percent of loss could be rehabilitated.
" Estimated by aerial photograph interpretation and ground truthing by a Reclamation biologist.

None of the alternatives traverse the seep wetlands or riparian areas, and measures would
be taken to protect these areas from indirect impacts during construction. The loss of
creosote-bursage habitat (caused by any of the alternatives) is not considered substantial
because of the large amounts of similar habitat in the nearby Mojave Desert.

Impact from Construction on Cliff Habitat. Some impact would occur to cliff habitat at the
bridge piers and abutments for all build alternatives. Highway construction would remove
about 50 vertical feet of cliff habitat on the Arizona side of the Sugarloaf Mountain and
Promontory Point bridges (out of about 800 vertical feet). The Gold Strike Canyon
Alternative would affect the greatest amount of cliff habitat, or 12.7 acres (Sugarloaf
Mountain, 1.4 acres and Promontory Point, 4.2). Loss of cliff habitat is more critical than
loss of creosote-bursage habitat because cliff habitat occurs in a limited area and provides
unique value to certain plants and wildlife. Cliff habitat near the Colorado River is
especially valuable because of its proximity to water.

Impact from Construction on Common and Special-Status Wildlife. During construction,
common and special-status wildlife species may be temporarily displaced due to habitat
alteration or noise disturbances from construction equipment. Implementing the build
alternatives would result in the permanent loss of 26 to 100 acres of potential wildlife
habitat (see Table 3-13). These habitats provide roosting, nesting, hiding, and foraging
SCO/CHAP3.WPD/003672775
3-27
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
habitat for wildlife species. Without migration, wide-ranging species such as predators and
desert bighorn sheep would permanently lose a portion of their foraging and breeding
habitat, resulting in lowered overall carrying capacities from loss of habitat and reduced
food sources. Breeding birds such as the black-throated sparrow would permanently lose
nesting habitat, cover, and feeding areas.

Construction would have the most pronounced and immediate affects on burrowing
rodents and reptiles with small territories. Individuals of those species would either be
killed or permanently displaced by excavation and other ground disturbance. It is
anticipated that the more mobile wildlife species using the proposed project area would
move from the area into surrounding habitats during construction.

Table 3-14 summarizes impacts of the three alternatives to special-status species. A
Biological Assessment prepared in 1992 by Reclamation addressed potential impacts to
listed species (Reclamation, 1992). This assessment determined that the alternatives may
affect the desert tortoise (all three build alternatives), peregrine falcon (Promontory Point
and Gold Strike Canyon Alternatives), and chuckwalla (Promontory Point and Gold Strike
Canyon Alternatives).

An updated Biological Assessment (BA) was prepared by FHWA and submitted to USFWS
with a letter dated February 17,1999, requesting formal consultation on the Sugarloaf
Mountain Alternative (FHWA, 1999). On June 3,1999, USFWS issued a Biological Opinion
for the Hoover Dam Bypass Project (Appendix E). This document represents the opinion of
USFWS on the potential effects of the proposed bypass project on federally listed species
under the Endangered Species Act of 1973.

The Biological Opinion concludes that the project will not likely affect the following
endangered species: bald eagle, American peregrine falcon, razorback sucker, southwestern
willow flycatcher, bonytail chub, and Devil's Hole pupfish. For the Mojave desert tortoise,
a federally listed threatened species, USFWS found that the project is not likely to
jeopardize its continued existence or adversely impact designated critical habitat. USFWS
stipulated "reasonable and prudent" measures to minimize project effects on the desert
tortoise (see Section 3.3.3.1).

A letter dated November 21,1997 from the USFWS to the FHWA verified the list of species
addressed in the 1992 Biological Assessment (USFWS, 1997). This list was recently updated
by USFWS in a letter dated December 5,2000; this verified the 1997 list for threatened and
endangered species (Appendix C).

Table 3-14
Comparison of Impacts of All Alternatives to Special-Status Species
Alternative
Species Promontory Point Sugarloaf Mountain Gold Strike Canyon
No Build
Devil's hole No effect
pupfish

Bonytail chub No effect
Razorback sucker No effect
No effect
No effect
No effect
No effect
No effect
No effect
Potential impacts from
hazardous material
spills
Potential impacts from
hazardous material
spills
Potential impacts from
hazardous material
spills
3-28
SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-14
Comparison of Impacts of All Alternatives to Special-Status Species

Alternative
Species
Chuckwalla
Promontory Point
Impact to rocky
habitat in mostly
disturbed habitat
Sugarloaf Mountain
Impact to the least
amount of rocky habitat
in mostly disturbed
areas
Gold Strike Canyon
Impact to the greatest
amount of rocky
habitat in mostly
undisturbed areas
No Build
No impacts .
anticipated
Desert tortoise
Peregrine falcon
Bald eagle
Desert bighorn
impact to 129
acres of marginal
habitat; may affect
8 tortoises in tow-
density population
Impact possible
without mitigation;
breeding territory
is within 1 mile of
bridge site
(NDOW, 1993)
Impact unlikely; no
known roosting
sites near bridge
site
Adverse impact to
25 acres of lamb-
ing habitat; access
to one natural
water source dis-
rupted; need for 9
crossing structures
Impact to 120 acres of
marginal habitat; may
affect 8 tortoises in tow
density population11

Impact possible without
mitigation; peregrines
may forage within
project area
Impact to 131 acres of Future minor loss of
marginal habitat; may habitat from
affect 9 tortoises in expansion of
low-density population transmission lines
Impact unlikely; no
known roosting sites
near bridge site

Adverse impact to 20
acres of lambing habitat;
impact to one human-
made water source;
need for 8 crossing
structures
Impact possible
without mitigation;
possible breeding
territory within 1 mile
of bridge site (NDOW,
1993)
Impact unlikely; no
known roosting sites
near bridge site

Adverse impact to 55
acres of lambing
habitat; access to 3
natural water sources
disrupted; need for 13
crossing structures
No impacts
anticipated;
expanding population
will stabilize
No impacts
anticipated; possible
establishment of
breeding population

Gradual increase in
highway mortality
Mountain lion"
Las Vegas bear
paw poppy
Bicolored
penstemon
Impact unlikely;
loss of 4.2 acres of
cliff habitat near
developed area
No impact;
gypsum soil not
found in this area
Impact possible;
disturbance to
0.3 acre of desert
wash
Impact unlikely; loss of
1.4 acres of cliff habitat
near developed area
No impact; gypsum soil
not found in this area
Impact possible;
disturbance to 0.3 acre
of desert wash
Impact possible; loss
of 12.7 acres of cliff
habitat in mostly
undisturbed, isolated
area
No impact; gypsum
soil not found In this
area
Impact possible;
disturbance to
10 acres of desert
wash
No impacts
anticipated;
population appears to
be expanding
No impacts
anticipated
No impacts
anticipated
Based on a review of the updated Biological Assessment (FHWA, 1999), USFWS determined in their Biological
Opinion that construction of the Sugarloaf Mountain Alternative may result in the direct loss of 5 federally
threatened Mojave desert tortoises in Nevada and 80 acres of Mojave desert tortoise habitat in Nevada (see
Biological Opinion, Appendix E).
b Mountain lions have been sighted several times throughout the proposed project area. Although the area is within
the historic range of the Yuma puma, the classification of lions presently residing in the proposed project area is
unknown.

Impact from Construction on Desert Tortoise (USFWS Biological Opinion, Appendix E).
USFWS determined in their June 3,1999, Biological Opinion that building the Sugarloaf
Mountain Alternative may result in the direct loss of 5 federally threatened Mojave desert
tortoises and 80 acres of Mojave desert tortoise habitat in Nevada. In addition, desert
SCO/CHAP3.WPD/003672775
3-29
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

tortoises found in the construction area and on access roads may be harassed by capture
and removal, resulting in an estimated 20 tortoises being harassed in association with
construction of the preferred alternative. An unknown number of desert tortoise eggs may
be destroyed during construction activities. Furthermore, an unknown number of tortoises
may be taken in the form of indirect mortality or harm due to increased predation by ravens
drawn to trash in the project area and from increased noise and ground vibrations
associated with construction.

Impacts will occur from grading and removal of vegetation, digging of tunnels, deposition
of spoil material, construction of new roads and bridges, and other activities requiring the
use of blasting, heavy equipment, and machinery. Desert tortoises may be killed or injured
by vehicles and may be harassed through removal from the construction area. The
proposed project could result in the death or injury of desert tortoises that move onto the
construction site and roads used by preconstruction and construction crews (Bury, 1978;
Luckenbach, 1975; and Nicholson, 1978). Vehicles that stray from the construction area and
roads may crush desert tortoises above ground or in their burrows. Habitat used by
tortoises for foraging, breeding, and cover will be temporarily disturbed or permanently
destroyed. Desert tortoises may be harmed by noise and ground vibrations produced by
vehicles and heavy equipment and by blasting operations (Bondello, 1976; and Bondello
et al., 1979). Shock waves from blasting may collapse burrows, thereby crushing tortoises.

Tortoises might be unlawfully collected as pets by project personnel, thereby removing
them from the wild population. Tortoises mat are physically moved out of project areas to
prevent mortality or injury could be inadvertently harmed if not handled properly. Urine
and large amounts of urates are frequently voided during handling, which may cause a
severe water loss, particularly to juveniles (Luckenbach, 1982). Overheating can occur if
tortoises are not placed in the shade when ambient temperatures equal or exceed
temperature maximums for the species (Desert Tortoise Council, 1996).

However, as discussed in the Biological Opinion (Appendix E), USFWS determined that the
level of effect resulting from the project will not reduce appreciably the likelihood of
survival and recovery of the Mojave population of the desert tortoise in the wild because:
| 1. Desert tortoise densities within the proposed project area are very low

2. The proposed project does not occur within conserved habitat or an area designated for
recovery of the desert tortoise

3. Impacts to desert tortoises within the project area represent a small impact to the
Mojave population of the desert tortoise when total desert tortoise population numbers
and geographical extent are considered.

Impact from Construction on Desert Bighorn Sheep. Construction and post-construction
activities would render some of the bighorn habitat unusable to a portion of the population
in the Black Mountains of Arizona and the El Dorado Mountains of Nevada. Construction
activities would occur in habitat where desert bighorn are accustomed to human activities
(e.g., traffic, blasting, and maintenance activities around Hoover Dam). However, it is
possible that construction could affect ewes during lambing season, causing a temporary
lambing decrease in a localized area. Ewes may breed late, prolonging lambing until later
in the spring when environmental conditions are less favorable (Cunningham and Hanna,
1992). Table 3-15 compares impacts of the alternatives on desert bighorn.
3-30 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM
Table 3-15
Comparison of Impacts of Build Alternatives on Desert Bighorn Sheep
Alternative
Impact
Promontory Point
Sugarloaf Mountain* Gold Strike Canyon"
Overall quality and
quantity of habitat
Moderate amount of
bighorn use
Nevada

Lowest amount of bighorn
use
Highest amount of
bighorn use
Relatively lower amount of
bighorn use
Arizona

Relatively higher amount
of bighorn use
Relatively higher amount
of bighorn use
Lambing habitat
Loss of about 25 acres of
lambing habttat
Nevada

No loss of lambing habitat
Loss of about 35 acres
of lambing habitat
No loss of lambing habitat
Arizona

Loss of about 20 acres of
lambing habitat
Loss of about 20 acres
of lambing habitat
Movement corridors
Alternative crosses one
major movement corridor
Nevada
Alternative crosses one
major movement corridor
Alternative crosses two
major movement
corridors
Alternative does not cross
major movement corridor
Arizona

Alternative crosses one or
more major movement
corridors
Alternative crosses two
major movement
corridors
Water sources
Alternative would not affect
water source
Nevada

Alternative would not
affect water source
Alternative would affect
the Gold Strike Canyon
ephemeral wash and
tributaries
Construction could disrupt
movement to water source
in Lake Mead
Arizona

Alternative would affect
one human-made water
source
Alternative would affect
one natural water source
8 Numerous minor crossings exist in both states.

Impact from Construction on Nesting Raptors and Protected Migratory Birds. Breeding raptors
(i.e., birds of prey), including peregrine falcon or other bkds protected by the Migratory Bird
Treaty Act may be nesting in the cliff habitat during construction. Construction impacts,
such as noise from equipment and increased traffic, may cause nest abandonment by
nesting birds. This would be an adverse impact.

Impact from Construction on Aquatic Communities. Construction of the new bridge and
associated highway approaches would minimally affect the aquatic environment in the
proposed project area of the three build alternatives. Cable-stayed and suspension bridge
types in the Promontory Point Alternative would require placing a pier in Lake Mead,
resulting in temporary, minor affects to Lake Mead water quality during construction in
that specific area. Implementing the project would increase turbidity and suspended
sediment during construction. Without mitigation, excessive sedimentation could
SCO/CHAP3.WPD/003672775
3-31
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

adversely affect the feeding, growth, and survival of downstream fish by reducing feeding
success, and by causing avoidance of rearing habitat.

The improved highway conditions with the build alternatives would significantly reduce
the potential for hazardous material spills in Lake Mead and the Colorado River by
reducing the risk of truck accidents on U.S. 93. Features to lessen the effects of hazardous
spills on the new bridge would include a drainage system on the bridge that would collect
liquid spills and drain the spills to holding basins at both ends of the bridge.

Impact from Construction on Waters of the United States. Figure 3-2 shows the three
proposed alignments and the washes that will be intersected by each alternative alignment.
Table 3-16 identifies the potential acreage of fill in waters of the United States for each
alignment based on the roadway and bridge designs in the Reclamation Phase B - Corridor
Studies (1992). The calculations of fill are separated into permanent and temporary impact
categories based on the assumptions listed below. The acreage of fill in waters of the
United States should be reassessed as more detailed highway designs become available.

Table 3-16
Acreage of Permanent and Temporary Fill In Waters of the United States for Each Alignment
Temporary Fill Permanent Fill
200-Foot Construction Area 50-Foot Impact Area
Alignment Each Side of the Centerline Each Side of the Centerline
Promontory Point* 0.76 0.14
Sugarioaf Mountain 0.66 0.11
Gold Strike Canyon 2.77 0.67
I " Impact areas of suspension bridge west tower: temporary 0.07 ac, permanent 0.06 ac
The following assumptions were used in calculating acreage of fill in waters of the
United States:
• An area 200 feet on each side of the Centerline of the alignments would temporarily be
used for access, construction staging and material stockpiling, or would be filled by
adjacent excavated materials. All stockpiled material would be removed following
construction.
• For the Gold Strike alignment, all of Gold Strike Canyon Wash from U.S. 93 to
Station 117+00, within and outside of the area 200 feet on each side of the Centerline,
would be used for heavy equipment access resulting in permanent alteration of the
wash and temporary fill in waters of the United States.
• An area 50 feet on each side of the Centerline of each alignment would be permanently
filled by either construction of the road base or side slopes.
• With the exception of the Promontory Point cable-stayed and suspension bridge types,
the area below the plane of the ordinary high water mark (OHWM) of the Colorado
River (Lake Mead and Lake Mohave) will not be filled by bridge construction on any
alignment. Span or arch bridges will be constructed. The Promontory Point bridge
west tower would be in the lake, and the impacted acreages are included in Table 3-16.2
2If the Promontory Point Alternative were selected, a U.S. Coast Guard permit under Section 9 of the
Rivers and Harbors Act would be required for construction of the bridge over Lake Mead. The fill
for bridge pier construction would also be subject to U.S. Army Corps of Engineers Nationwide
Permit #15 under Section 404 of the Clean Water Act.

3-32 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Bridge construction for all other drainages will result in permanent fill in waters of the
United States. Structural piers, retaining walls, and abutment excavation associated
with the bridge construction will result in fill in waters of the United States.

3.3.2.2 Operational Impacts
Impact of Operation on Common and Special-Status Wildlife. Without planned fencing,
increased road kill of wildlife is expected. Wildlife regularly using the area in the vicinity
of the new alternative would be expected to cross the roadway at some location. Nocturnal
birds and mammals are especially at risk of collision due to temporary blindness from
vehicle lights (Schultz, 1986).

Impact Of Operation on Desert Tortoise. According to the USFWS Biological Opinion
(Appendix E), postconstruction indirect effects will result from operation of the proposed
project. These effects are later in time and are reasonably certain to occur. Obviously, road
kills of tortoises on the new highway are a direct, adverse impact on this wildlife
population. However, indirect effects during operation and maintenance are subtle and
may affect tortoise populations and habitat quality over an extended period of time.
Indirect effects are of particular concern for long-lived species such as the tortoise because
project-related effects may not become evident in individuals or populations until years
later.

Operation and maintenance (as well as construction) activities associated with the project
may create trash and litter or standing water adjacent to the highway facility that could
attract tortoise predators such as the common raven, kit fox, and coyote (Berry, 1985; and
BLM, 1990). Natural predation in undisturbed, healthy ecosystems is generally not an issue
of concern. However, predation rates may be altered when natural habitats are disturbed or
modified. Common raven populations in some areas of the Mojave Desert have increased
1,500 percent from 1968 to 1988 in response to expanding human use of the desert
(Boarman, 1992). Since ravens were scarce in this area prior to 1940, the current level of
raven predation on juvenile desert tortoises is considered to be an unnatural occurrence
(BLM, 1990).

Impact Of Operation on Desert Bighorn Sheep. Results of studies by Cunningham and Hanna
(1992) and Ebert and Douglas (1993) show that the main threat of project implementation to
desert bighorn is an increase in vehicle and bighorn collisions. The main concern of NDOW
and AGFD has been the existence of a new four-lane, high-speed highway in bighorn
habitat that would increase the number of animals killed along the highway.

No Build Alternative. Existing conditions will continue under the No Build Alternative. An
increase in truck accidents, as a result of traffic congestion and current highway conditions,
could increase in the potential for hazardous material spills in Lake Mead and the Colorado
River. In addition, the added congestion and increase in road traffic may result in an
increase of vehicle-wildlife collisions on U.S. 93.

3.3.3 Measures to Minimize Harm
3.3.3.1 Construction Mitigation
Approximately 50 percent of the total land disturbed within the highway right-of-way will
be revegetated. Topsoil will be stockpiled as much as possible during construction and
replaced on disturbed areas directly outside the highway shoulders after construction to
SCO/CHAP3.WPD/003672775 3-33
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

| re-establish desert vegetation. Salvaged cacti, yucca, and candidate plant species will be
removed, stockpiled, and replanted.

Desert washes will be protected by placing barriers below excavation areas to prevent
construction spoil from falling in the washes. In addition, several sections of washes will be
bridged. Culverts placed in fill areas will be installed to allow runoff to flow unrestricted,
and erosion protection devices will be placed at the ends of each culvert. For construction
of bridge abutments, loose rocks will be scaled prior to and during excavation work, and
netting on the canyon slopes will be used during blasting to minimize rock fall and
contamination of Colorado River waters.

Wildlife drinking sources currently used by desert bighorn sheep, which could be directly
affected by construction, will be relocated to nearby areas. They will be placed so that they
are easily found by resident sheep but are far enough from the construction site so that
sheep could use the new water source without being disturbed by construction. Specific
types and locations of these offsite watering facilities will be determined through
consultation with the AGFD, NFS, and NDOW.

Several underpasses and overpasses will be strategically located near traditional bighorn
sheep movement corridors to provide safe crossings for them and other wildlife and to
prevent small populations from being isolated. Additionally, highway bridges (included in
the highway because of topographic demands) will also provide safe crossings. The
location, design, and number of crossing structures were determined during consultations
among wildlife biologists from AGFD, NDOW, NFS, and Reclamation. These criteria were
based on studies conducted by AGFD and NFS from 1989 through 1992 in conjunction with
this project. The numbers of crossing structures are summarized in Table 3-17 and are
shown on Figures 2-4,2-8, and 2-11.

Table 3-17
Estimated Number of Wildlife Crossing Structures for Each Alternative*
Alternative
Crossing Structure Type Promontory Point Sugarloaf Mountain Gold Strike Canyon
Wildlife underpass 64 2
Wildlife overpass 2 3 1
Highway bridge 1 2 10
Tunnel 1 1 1
* Source: Reclamation, 1992
Fencing will be placed along both sides of the highway corridor to guide wildlife to
crossing structures, thereby reducing the potential for animals being killed. Fencing will be
continued approximately 0.5 mile beyond the intersections of the new highway with
existing U.S. 93 in Arizona. Monitoring to determine the effectiveness of the
above-mentioned physical mitigation features will be conducted following construction
activities. Specific monitoring procedures and duration of effort will be determined
through consultation with NPS, AGFD, USFWS, and NDOW.

Desert Tortoise. In the Biological Opinion regarding construction of the Sugarloaf Mountain
Alternative, USFWS determined the reasonable and prudent measures necessary and
appropriate to minimize take of Mohave desert tortoises in Nevada. The Biological Opinion
also stipulates terms and conditions for implementation of the reasonable and prudent
measures, as follows (see Biological Opinion, Appendix E, for full details):
3-34 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

1. Measures shall be taken to minimize mortality or injury of desert tortoises due to
construction activities, blasting operations, and use of heavy equipment.

a. Prior to the initiation of construction, a desert tortoise education program will be
presented to all personnel who will be onsite, including surveyors, construction
engineers, employees, contractors, contractors' employees, supervisors, inspectors,
subcontractors, delivery personnel, and all visitors operating a vehicle in the project
area. This program will contain information concerning the biology and distribution
of the desert tortoise, its legal status and occurrence in the project area, the definition
of "take" and associated penalties, the measures designed to minimize and mitigate
the effects of construction activities, the means by which employees can help
facilitate this process, and reporting procedures to be implemented in case of desert
tortoise encounters.

b. At least 7 days, and no more than 30 days, prior to the initiation of construction
within right-of-ways without tortoise-proof fencing, a qualified biologists) will
survey the site for desert tortoises using techniques providing 100 percent coverage.
Transects will be no greater than 10 meters apart. The site boundaries will be
flagged prior to me biological survey.
All burrows found in the construction zone, whether occupied or vacant, will be
excavated by a qualified biologist and collapsed or blocked to prevent desert tortoise
re-entry. All burrows will be excavated by hand with hand tools to allow removal
of desert tortoises or desert tortoise eggs. All desert tortoise handling and burrow
excavations will be conducted by a qualified desert tortoise biologist in accordance
with USFWS-approved protocol (Desert Tortoise Council, 1994 [revised 1996]).

c. All desert tortoises and desert tortoise eggs located in the linear right-of-way will be
relocated 300 to 1,000 feet into adjacent undisturbed habitat. Tortoises found above
ground will be placed under a marked bush in the shade. A tortoise located in a
burrow will be placed in an existing unoccupied burrow of the same size and
orientation as the one from which the tortoise was taken. If a suitable natural
burrow is unavailable, a qualified biologist will construct one of the same size and
orientation as the one from which the tortoise was removed utilising the protocol for
burrow construction in section B.5.f (Desert Tortoise Council, 1994 [revised 1996]).
Any tortoise found within 1 hour before nightfall will be placed in a separate dean
cardboard box and held overnight in a cool location. The box will be covered and
kept upright at all times to minimize stress to the tortoise. Each box will be used
once and then disposed of properly. The tortoise will be released the following day
in the same area from which it was collected, using the procedures described above.
Each tortoise will be handled with a different pair of disposable latex gloves. After
each use, the gloves will be properly discarded and a fresh set used for each
subsequent tortoise handling.
d. Desert tortoises will be moved only by a qualified desert tortoise biologist and solely
for the purpose of moving them out of harm's way. Appropriate State permits will
be acquired from NDOW prior to handling any live desert tortoise, desert tortoise
carcass, or desert tortoise egg.

e. All desert tortoises observed by project workers will be reported immediately to the
qualified biologist, who will move the tortoise off site into adjacent undisturbed
SCO/CHAP3.WPD/003672775 3-35
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

habitat. Tortoises will be handled only when necessary and in accordance with
guidelines provided in the Biological Opinion.

f. If blasting is required in desert tortoise habitat, a desert tortoise biologist will be
assigned to each blasting crew or to each area in which blasting will occur. Prior to
any blast, a 200-foot radius around the blast site will be surveyed for desert tortoises
using techniques providing 100 percent coverage; transects will be no greater than
10 meters apart. Aboveground tortoises will be relocated at least 500 feet from the
blast site. Desert tortoises located in burrows that are within 50 feet of the blast site
will be relocated at least 75 feet away from the blast site to an unoccupied existing
burrow of the same size and orientation. If a suitable existing burrow is unavailable,
an artificial burrow of the same size and orientation will be constructed by an
approved biologist utilizing USFWS-approved protocol (Desert Tortoise Council,
1994 [revised 19%]). Burrows either occupied by desert tortoise or with
undetermined occupancy status and located 50 feet or further away from the blast
site will be flagged and stuffed with newspaper prior to the blast. The newspaper
will be removed immediately after the blast and the burrows assessed for damage.

g. Any time a vehicle is parked in desert tortoise habitat, the ground around and
underneath the vehicle will be inspected for desert tortoises prior to moving the
vehicle. If a desert tortoise is observed, an authorized biologist will be contacted. If
possible, the tortoise will be left to move on its own. If the tortoise does not move
within 15 minutes, the tortoise will be removed and relocated by the authorized
biologist in accordance with the tortoise handling provisions of the Biological
Opinion.

h. Herbicides shall not be used in the project area unless approved in writing by
USFWS.

i. Vehicles shall not exceed the legal speed limit (posted or unposted) of the roads
used during construction activities. The Clark County speed limit for unposted
roads is 25 mph.

2. Measures shall be taken to minimize predation on tortoises by ravens drawn to the
project area.

Trash and food items will be disposed of promptly in predator-proof containers with
resealable lids. Trash includes, but is not limited to, cigarettes, cigars, gum wrappers,
tissue, cans, paper, and bags. Trash containers will be removed regularly (at least once
per week). This effort will reduce the attractiveness of the area to opportunistic
predators such as desert kit fox, coyotes, and common ravens. Any construction refuse,
including, but not limited to, broken parts, wrapping material, cords, cables, wire, rope,
strapping, twine, buckets, metal or plastic containers, boxes, and welding rods will be
removed from the site each day and disposed of properly.

3. Measures shall be taken to minimize destruction of desert tortoise habitat, such as soil
compaction, erosion, or crushed vegetation, due to construction and maintenance
activities.

a. Project vehicles will remain within designated areas or on existing roads. Off-road
travel is prohibited except to complete a specific task within designated areas or in
emergency situations.
3-36 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

b. All areas to be disturbed will have boundaries flagged prior to construction, and all
disturbance will be confined to the flagged areas. All employees will be instructed
that their activities must be confined to locations within the flagged areas.
Disturbance beyond the actual construction zone is prohibited.
c. Stockpile areas, vehicle turn-arounds, and vehicle service locations will be approved
by Reclamation or NFS prior to the initiation of construction activities. These areas
will be surveyed for desert tortoise and desert tortoise eggs. Any desert tortoises or
desert tortoise eggs found within these areas will be removed in accordance with the
tortoise handling provisions of the Biological Opinion. Whenever possible, stockpile
areas, vehicle turn-arounds, and vehicle service locations will be restricted to
previously disturbed areas. If not in previously disturbed sites, stockpile areas,
vehicle turn-arounds, and vehicle service locations will be considered habitat
disturbance for payment of remuneration fees.
d. Topsoil will be removed to a depth of 6 to 12 inches in all areas of potential seed-
bearing soil where ground breaking will take place. The determination of which
soils are potentially seed-bearing will be the responsibility of the tortoise biologist.

e. Removed topsoil will be stockpiled in a separate area and designated as "topsoil" to
prevent contamination by or combination with other excavated soils. Reasonable
measures will be taken to ensure the protection and preservation of the stockpiled
topsoil to prevent loss of the seed bed from wind and rain or contamination by other
soils or manmade contaminants. Stockpile areas for topsoil will be located in areas
that are secure from construction traffic or flash floods.
f. Excavated tunnel material will be disposed of in designated areas previously
approved by the individual Federal agency that has administration authority over
the affected land.
g. Equipment and materials storage will be located in previously disturbed areas
whenever possible. If not in previously disturbed sites, equipment and storage areas
will be considered habitat disturbance for payment of remuneration fees.

h. Any fuel or hazardous waste leaks or spills will be stopped or repaired immediately
and cleaned up at the time of occurrence. USFWS/maintenance vehicles will carry a
bucket and pads to absorb leaks or spills.
i. Contaminated soil will be removed and disposed of at an appropriate facility. If
spills occur in a maintenance yard, they will be cleaned up after construction is
complete.
j. All waste and leftover materials remaining after construction of this project will be
removed from the site after project completion.

k. Prior to initiation of construction, FHWA shall ensure that $587 per acre of
disturbance is paid into the account administered by Clark County for the Clark
County Desert Conservation Plan (CCDCP) as off site mitigation for destruction of
desert tortoise habitat resulting from the project. This rate will be indexed for
inflation based on the Bureau of Labor Statistics Consumer Price Index for All Urban
Consumers (CPI-U) on January 31 of each year. Fees assessed or collected for
projects covered under the Hoover Dam Bypass Biological Opinion after January 31st
of each year will be adjusted based on the CPI-U.
SCO/CHAP3.WPD/003672775 3-37
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

This fee will be paid directly to the Desert Tortoise Public Lands Conservation Fund
Number 730-9999-2315 administered by Clark County. The administrator serves as
the banker of these funds and receives no benefit from administering these funds.
These funds are independent of any other fees collected by Clark County for desert
tortoise conservation planning.

The payment shall be accompanied by the Section 7 Fee Payment Form (Biological
Opinion, Appendix E) and completed by the payee. The project proponent or
applicant may receive credit for payment of such fees and deduct such costs from
desert tortoise impact fees charged by local government entities.

FHWA anticipates that 80 acres of desert tortoise habitat will be disturbed as a
result of the proposed project, requiring $46,960 in remuneration fees.
4. Measures shall be taken to ensure compliance with the reasonable and prudent
measures, terms and conditions, reporting requirements, and reinitiation requirements
contained in this biological opinion.
a. FHWA will designate a field contact representative responsible for overseeing
mitigation compliance and for coordination with the agencies.
b. A qualified biologist(s) will be available during all phases of construction. In
accordance with Procedures for Endangered Species Act Compliance for the Mojave Desert
Tortoise (USFWS, 1992), a biologist should: (1) possess a bachelor's or graduate
degree in biology, ecology, wildlife biology, herpetology, or related fields; (2)
demonstrate a minimum of 60 days of prior field experience using accepted resource
agency techniques to survey for desert tortoises; and (3) have the ability to recognize
and to accurately identify and record all types of desert tortoise sign.
c. The qualified biologist(s) will be responsible for determining compliance with
mitigation measures as defined by the Biological Opinion. Qualified biologist(s) will
have the authority to briefly halt construction and maintenance activities that are not
in compliance with the terms and conditions of the Biological Opinion.
Construction and maintenance activities will be halted only long enough to remedy
the immediate situation and will apply only for the equipment and parties involved
in the situation. All actions of noncompliance or conditions of threat to federally
proposed or listed species will be recorded immediately by the qualified biologist(s)
and reported to FHWA. FHWA will immediately report all such actions and
conditions to USFWS.
d. All fuel or hazardous waste leaks, spills, or releases will be reported immediately to
FHWA and the Federal agency that administers the land where the incident occurs.
e. Upon locating dead or injured desert tortoises, the field contact representative will
notify FHWA immediately by phone and within 5 days by writing. Initial
notification also must be made immediately to the Division of Law Enforcement of
the USFWS in Las Vegas, Nevada. Written notification to USFWS will be made
within 15 days of the date of the finding or incident and will include the following
information: (1) date and time of finding or incident; (2) location of carcass or
injured tortoise; (3) a photograph; (4) cause of death or injury; and (5) other
pertinent information. Care will be taken in the handling of sick or injured
specimens to ensure effective treatment and care, and in the handling of dead
specimens to preserve biological material in the best possible state for later analysis
of cause of death. In conjunction with the care of a sick or injured desert tortoise or

3'38 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

preservation of the biological materials from a dead desert tortoise, the finder has
the responsibility to carry out instructions provided by the Division of Law
Enforcement of the USFWS to ensure that evidence intrinsic to the specimen is not
unnecessarily disturbed.
f'. The qualified biologist(s) will maintain a record of each observation of desert
tortoise during the project. The information gathered will include the following:
(1) location; (2) date and time of observation; (3) whether tortoise was handled; (4)
general health and whether it voided its bladder; (5) location tortoise moved from
and location moved to; and (6) any observed unique physical characteristics of each
individual.
g. FHWA and a qualified biologist will prepare a report to be distributed to NFS,
Reclamation, USFWS, and NDOW no later than 90 days following the completion of
construction activity. The report will document the number and location of desert
tortoises encountered, their disposition, effectiveness of mitigation measures,
practicality of mitigation measures, recommendations for future mitigation
measures that allow for better protection or more workable implementation, and an
estimate of acreage disturbed.

Desert Bighorn Sheep. Fencing will be constructed and maintained to prevent desert
bighorn sheep from entering the highway. Out-jumps will be constructed at strategic
locations to provide an escape for any sheep accidentally trapped inside the fenced
highway right-of-way. Roadside signing will be installed warning motorists of the
possibility of encountering wildlife in the area. In addition, crossing structures will be
incorporated into the highway design to allow bighorn movement through established
movement corridors. With the mitigation features currently planned, the project could
probably result in a net overall reduction of animals killed along or on the highway.
Movements to water sources during summer could be disrupted during and immediately
after construction by the presence of the highway. Alternate water sources will also be
provided for mitigation.
A mitigation monitoring plan will be implemented in consultation with AGFD, NDOW,
and NFS. The plan will assess effectiveness of the crossing structures, fencing, and
alternate water sources. Adjustments will be made, if needed.
Peregrine Falcon. Biologists from AGFD and NFS will monitor peregrine falcons in the |
proposed project area 3 to 4 times per year at least 2 years before, during, and after 1 year of
public use of the new Colorado River bridge. NDOW will coordinate their ongoing |
peregrine falcon surveys in the area with AGFD and NFS.

If breeding territories are found within 0.5 mile of construction activities, consultation will I
be reinitiated with USFWS to determine appropriate mitigation measures. |
Bald Eagle. Biologists from AGFD, NFS, and Reclamation will monitor bald eagle use of the
bridge crossing sites during two consecutive winters before construction, and any preferred
hunting perch sites or night roosting sites will be identified. Measures will be taken to not
affect any preferred hunting perch sites or night roosting sites for bald eagles. If bald eagles
were to nest in the project vicinity, consultation with USFWS will be reinitiated.

Devil's Hole Pupfish. No construction below the waterline will occur in the Colorado River
in Black Canyon. For construction of the Sugarloaf Mountain alignment, a catch net and
temporary spill containment system will be constructed at the Colorado River crossing to
catch falling debris and collect contaminants if spilled. For construction of bridge

SCO/CHAP3.WPD/003672775 3-39
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

abutments, loose rocks will be scaled prior to and during excavation work, and netting on
the canyon slopes will be used during blasting to minimize rock fall.

An assessment of the potential effects of the blasting activities of the project will be
completed prior to implementation. If the assessment identifies unavoidable impacts to the
Devil's Hole pupfish, formal consultation with USFWS will be initiated, and appropriate
conservation and mitigation measures will be included in the Biological Opinion.

Razorback Sucker. No construction below the waterline will occur in the Colorado River in
Black Canyon. As for the Devil's Hole pupfish, measures will be taken to ensure that any
falling debris from the cliffs will not affect water quality that could affect razorback suckers
further downstream of the Hoover Dam or in Lake Mohave.

If the assessment identifies unavoidable impacts to the razorback sucker, formal
consultation with USFWS will be initiated, and appropriate conservation and mitigation
measures will be included in the Biological Opinion.

Bonytail Chub. There will be no construction below the waterline in the Colorado River in
Black Canyon. Measures will be taken to ensure that any falling debris from the cliffs will
not affect water quality that could affect the bonytail chub further downstream in Lake
Mohave.

| Mountain Lion. Mitigation measures for desert bighorn sheep will also mitigate effects to the
mountain lion population.

Bicolored Penstemon. Preconstruction surveys of bicolored penstemon will be performed.
Plants found within the construction right-of-way will be salvaged, as will topsoil possibly
containing penstemon seeds. Any salvaged plants will be stockpiled and replanted within
the constructed highway right-of-way.
Migratory Birds. No land clearing will occur during the avian breeding season. Actions will
be taken to ensure that no migratory birds, their nests, or nest contents, will be harmed
during construction.

Waters of the United States. Temporary impacts will be avoided or minimized by
designating construction access, stockpile, and staging areas outside of waters of the United
States and by designing effective rock debris restraints on steep slopes. In many locations,
especially on the Gold Strike Canyon alignment, the proposed road is located on steep
rocky slopes. Excavation of a road base will result in the need to move considerable
amounts of rock debris. In the absence of effective barriers, this material will fall into the
adjacent washes. This potential fill is included in the temporary impacts to waters of the
United States.

Permanent impacts can be minimized on the Gold Strike Canyon alignment. This could be
accomplished by placement of span bridges in place of road fill at many locations. Impacts
may be further reduced by bridge design and bridge construction methods that minimize or
avoid all fill in waters of the United States. Avoiding impacts to waters of the United States
at bridge crossings will reduce permanent impacts on the Sugarloaf Mountain alignment
from 0.11 to 0.07 acre and on the Gold Strike Canyon alignment from 0.67 to 0.38 acre.
Placement of the Promontory Point west bridge pier (for the cable-stayed and suspension
designs) in the waters of Lake Mead would require Section 10 and Section 404 U.S. Army
Corps of Engineers and Section 9 U.S. Coast Guard permits for navigable water crossings
and placement of bridge and fill in waters of the United States.

3-40 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Permanent impacts can be further reduced by highway design and highway construction
methods that will reduce the fill to less than 50 feet on either side of the centerline in the
vicinity of waters of the United States.

3.3.3.2 Operational Mitigation
NDOT and ADOT will maintain wildlife underpasses and overpasses in their respective
states. Alternate water sources provided for mitigation will be maintained by either NFS or
Reclamation. Reclamation sewage evaporation ponds will be replaced as a wildlife
watering source, or a new source will be provided if relocated ponds are fenced (with
Sugarloaf Mountain Alternative).

3.4 Water Resources

3.4.1 Affected Environment

Annual precipitation in Las Vegas Valley averages 4.1 inches per year (National Oceanic
and Atmospheric Administration, 1991). Precipitation rates in the proposed project area are
similar.

Several natural drainages occur along the three build alternative alignments (Figure 3-3).
Most are narrow (1- to 3-feet wide) washes that drain a local watershed of approximately
2 acres. However, two broader intermittent desert washes (from a few feet to more than
20 feet wide) drain watersheds of more than 50 acres in the proposed project area. One is a
medium-sized, unnamed drainage that runs in a north-south direction west of U.S. 93 in
Arizona, intersecting each of the build alternatives.

The other of the larger drainages (Gold Strike Canyon Wash) runs along the Gold Strike
Canyon Alternative. At the lower end of the wash, before terminating at the Colorado
River, are hot springs that produce year-round runoff into the river. The only water courses
with perennial flows existing in the proposed project area are the Colorado River, Lake
Mead, and the lower Gold Strike Canyon Wash (supplied by hot springs). The remainder of
the washes are intermittent.

The River Mountains to the northwest, Lake Mead to the north, and Lake Mohave to the
south flank the proposed project area. Lake Mead can store nearly 2 years of average
Colorado River flow. When full, Lake Mead is 110 miles long with an 822-mile shoreline
and a capacity of 26 million acre-feet. The figure that NPS uses most often is based on the
average lake elevation of 1,200 feet, resulting in a shoreline 714 miles long. If the shoreline
for Lake Mohave is also included, the length is approximately 953 miles long.

No known groundwater resources are located within the River Mountains or along the
mountain flanks. Alluvial aquifers within Las Vegas Valley supply about 15 to 20 percent
of the water to Las Vegas Valley. The River Mountains are not known to be a source of any
significant recharge to these alluvial aquifers (Malmberg, 1965). In addition, the volcanic
rocks composing the mountains are not considered suitable for the formation of useful
aquifer systems (Plum, 1989). However, there may be fracture porosity within the rocks
that could contain groundwater at elevations below the level of Lake Mead. No known
water wells are located in the vicinity of the proposed project area.

FiOOdplains. The Federal Government created the National Flood Insurance Program
(NFTP) in 1968. This program is an effort to reduce the financial losses incurred by private
citizens and public entities from the devastating effects of flooding. The program is

SCQ/CHAP3.WPD/003672775 3-41
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

administered by the Federal Insurance Administration (FIA), a division of the Federal
Emergency Management Agency (FEMA).

Flood zones designated as "X" zones are minimal to moderate risk flood zones. Flood
zones designated as "A" zones are one of two Special Flood Hazard Area (SFHA) zones that
are subject to damage from rising water. FEMA maps obtained from Clark County, Nevada
and Mohave County, Arizona for the project area indicate that, while the Colorado River
itself is considered to be a Zone A flood potential, the surrounding land areas, by virtue of
their elevations, are designated as Zone X.

3.4.2 Environmental Consequences

3.4.2.1 Construction Impacts
Runoff draining to and from the project during construction will impact water quality.
New cut and fill slopes will erode by a combination of sheet, rill and concentrated flow.
The eroded material will travel downslope and eventually enter the channel network
characteristic of each alternative. Once in the channel, the sediment can travel downstream
provided the channel characteristics and runoff volume are adequate to sustain material
movement. At natural channel crossings, disturbed channel sections will erode creating
point sources of sediment and potentially long-term disruption to channel stability.

Channel bypass systems will be constructed in areas where runoff is diverted around the
work site. These systems will be temporary features, small in geometric cross section (i.e.,
2-foot-deep v-channel with 2:1 slopes, at a minimum) and generally not constructed
adequately to sustain long-term use. Their use will result in large volumes of soil being
eroded from the channel and transported through the site. The volume removed and
deposited will be proportional to the bypass channel length and slope.

Temporary access roads will be constructed, and occasionally sections will be washed away
from storm runoff. Material from these roads will potentially make it to live water. In
addition to washed out road sections, other segments might be weakened and fail during a
lesser runoff event. In general, with sediment movement, the closer the eroded material is
deposited to live water, the higher the probability that with time the sediment will actually
enter it.

Equipment working along the construction site will also contribute to water quality
impacts. Construction equipment will leak various petroleum compounds contaminating
isolated areas of the work site. When these areas come in contact with runoff, the
compound(s) will be mobilized and could potentially enter live water. Areas utilized for
fueling equipment will also be prone to contamination from spills and can be transported
when runoff is present. Other sources of construction-related contamination will result
from materials such as concrete, concrete and asphalt coatings, and emulsions being
delivered to the construction site. The equipment used for delivery of these products would
be cleaned after the delivery. The waste material will be discharged within the construction
corridor and will become mobilized during storm events.

The roadway profiles vary from less than 0.5 percent to slightly greater than 6 percent. For
the Promontory Point and Sugarloaf Mountain Alternatives, approximately 80 to 90 percent
of the alignment is less than 3 percent. For the Gold Strike Canyon Alternative, only about
29 percent of the alignment is less than 3 percent. Typically for disturbed areas, steeper
ditch grades result in increased erosion.

3-42 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Of the three alternatives, the Gold Strike Canyon alignment should have the greatest
potential for impacting water quality from erosion during construction. Cut and fill slopes
in the lower canyon sections will have the greatest impact on the Colorado River water
quality due to the relatively short travel distance to the river. The alternative having the
second greatest potential for impacting water quality is the Sugarloaf Mountain alignment
followed closely by the Promontory Point alignment. These latter two alternatives are
constructed on similar terrain. However, since the Sugarloaf Mountain Alternative has a
slightly steeper overall slope, the erosion potential is greater.

Equipment impacts to water quality for each alternative will also differ. Due to the steeper
slopes associated with the Gold Strike Canyon Alternative, spills and discharges from
equipment will quickly travel downslope and have the potential for reaching live water
sooner than the other two alternatives. However, during bridge construction, the potential
for contamination directly to live water is greater for the Promontory Point alignment due
to the increased time necessary to construct the longer bridge over live water. In addition,
pier construction would require extensive dewatering operations and erosion control BMPs.
This type of construction significantly increases the potential for accidents during
construction and the unanticipated release of concrete or sediment into waters of the U.S.

3.4.2.2 Operational Impacts
Once the construction is completed and the roadways are functional, the various
alignments will still impact water quality. Exposed cut and fill slopes will continue to erode
until stabilized by vegetative or mechanical means. Discharge from culverts and roadway
channels will cause erosion due to steep slopes and elevated velocities unless properly
designed. Additional runoff generated from the road surface, if uncontained, will carry
pollutants and trash offsite or deposit them directly in live water if originating from bridge
surfaces. Chemical spills resulting from vehicle accidents are a possibility and, if
uncontained, will impact water quality. Therefore, long-term impacts to water quality from
operation of the bypass could exceed the actual construction impacts if not properly
mitigated.
Since the roadway surface is impermeable, essentially all precipitation falling on it will
travel from the surface as runoff to catch basins and then to nearby natural channels. This
additional runoff is not expected to increase downstream flood flows in nearby channels
since the roadway runoff will enter the channel system prior to the generation of the local
or regional peak flow. The roadway runoff will increase the localized volume in the nearby
channels, but this is not expected to pose any problems. The volume in most cases will be
small when compared to that generated on a local or a regional basis. As a result, no
impacts to flood flow or floodplains are anticipated from the alternatives.
Runoff generated from bridges that directly discharge to receiving waters or channels could
alter localized water quality. Unlike roads, bridges typically do not accommodate vehicle
parking except under emergency conditions such as vehicle breakdown. As such, the level
of contamination resulting from pollutants is probably low to warrant treatment of the
runoff. Normally the bulk of pollutants originating from roadway surfaces are removed
from the road surface by the "first flush" or initial runoff generated during a storm.
The Gold Strike Canyon Alternative is anticipated to have the greatest impact to water
quality during roadway operations. Due to the steep slopes associated with the road
profile, sediment generation from the slopes, channels, and culvert outfalls will be higher
than the other two alternatives, unless mitigation measures are implemented. The
alternative having the next greatest impact would be theSugarloaf Mountain Alternative,

SCO/CHAP3.WPD/003672775 3-43
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

due to its steeper overall slopes when compared to those of the Promontory Point
Alternative.
When considering water quality impacts resulting from bridge-generated runoff, the Gold
Strike Canyon Alternative poses the greatest impact due to the combined length of all the
bridges along the alignment. The Sugarloaf Mountain Alternative would have the second
greatest impact followed by the Promontory Point Alternative. However, when just
considering the longest single Colorado River/Lake Mead crossing, Promontory Point is
ranked first, then Sugarloaf Mountain followed by Gold Strike Canyon Alternative. This is
based strictly on bridge length without implementing mitigation measures. In addition, an
uncontained spill on the Promontory Point bridge over Lake Mead has the potential to
contaminate or make unusable the water stored for future use.
Floodplains. Each of the three build alternatives will transversely encroach into an area
designated as Zone A flood potential, as they cross the Colorado River. The degree of
encroachment is somewhat higher for the Promontory Point Alternative since it crosses
Lake Mead with a longer bridge upstream of Hoover Dam. The degree of encroachment of
the build alternatives will be limited to bridge piers and abutments supporting the
structures. These structural encroachments will not be of sufficient extent/volume to cause
the existing water surface elevation to increase substantially. If these structural
encroachments result in a cumulative rise in water surface elevation of less than 1 foot, the
established standard of the NFIP, the level of flooding risk associated with the three build
alignments would be considered low.
No Build Alternative. Although the No Build Alternative would avoid the potential short-
term impacts to local water quality resulting from erosion and spills during construction
activities, runoff from U.S. 93 across Hoover Dam presently impacts local water quality.
This impact is primarily from road surface runoff which carries pollutants from the current
heavy traffic usage of the highway. In addition, transportation of hazardous materials
across the dam results in an increased potential for accidental spills that could significantly
impact waters of Lake Mead and the Colorado River. Reclamation currently maintains a
facility-specific emergency preparedness plan for Hoover Dam to deal with potential
hazardous material transport accidents that might occur on the dam crest and approaches.
The Hoover Dam Police standard operating procedures also contain provisions for
responding to accidental hazardous material spills (personal communication, Jeff Weaver
July 15,1998). However, there is no on-site containment facility to handle hazardous
material or waste spilled in a trucking accident on or near the dam crossing.

Under the No Build Alternative, the environmental benefits to local water resources from
removing conventional traffic and hazardous material transporters from the dam to a new
bridge, which incorporates an engineered runoff conveyance system, will not be realized.

3.4.3 Measures to Minimize Harm

Implementation of Best Management Practices (BMPs) along the project corridor will
dramatically reduce water quality impacts to the Colorado River below Hoover Dam. Both
construction and operational impacts are to be mitigated through the use of BMPs. During
construction, it will be imperative to manage stormwater runoff above and below the
project so that the net impact to receiving water is negligible. This will be achieved by
routing upslope runoff around the construction site, minimizing exposure to disturbed
slopes, and collecting and treating onsite runoff and discharging it so that the water quality
entering the receiving waters is not impaired.

3.44 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

During system operation, channels conveying roadway-derived runoff will be designed to
resist erosion. Cut-and-fill slopes will be stabilized using vegetative and/or mechanical
means, and roadway-derived runoff will be captured and treated to remove suspended
solids prior to discharging from the project area.

For both the construction and operation phase, the main concern will be to isolate runoff-
rich suspended sediment in treatment basins. By ignoring this issue, the volume of runoff
derived from this project, although small, could potentially impact receiving water quality
to varying degrees. Immediately downstream of the project area, sediment-rich roadway
runoff could mix with unimpaired runoff and degrade localized water quality. Further
downstream, as additional runoff water is added, the impacts from the project area are
reduced due to dilution. By the time the roadway runoff enters the Colorado River, water
quality from the roadway would most likely be negligible. Based on the anticipated
impacts to water quality immediately downstream of the roadway, water quality
parameters, such as suspended solids, turbidity, color and total dissolved solids (IDS), will
be elevated if not collected and treated. It is possible this runoff could exceed the threshold
limits for suspended solids and turbidity. Collecting and treating this runoff prior to
discharging to natural drainage channels will prevent impacts to localized water quality.

The standards of water quality below Hoover Dam that will be pertinent to this project are
as follows:
Parameter
Temperature °C - maximum
AT°
pH Units
Total Phosphates
(asP)-mg/L
Nitrogen Species
(N) - mg/L
Dissolved Oxygen - mg/L
Suspended Solids - mg/L
Turbidity - NTU
Color -PCU
Total Dissolved Solids - mg/L
Alkalinity
(as CaCO3) - mg/L
Water Quality Standards for Beneficial Uses
Nov.-Apr.:<13°C
May-June: <17°C
July-Oct.: < 23°C
AT0 < 2°C
S.V.:7.0-8.3
ApH: + 0.5 Max.
A-Avg.: < 0.05
Nitrate S.V.: < 10
Nitrate S.V.: < .06
Ammonia S.V.: < .02
(un-ionized)
S.V.
Nov.-May: > 6.0
June-Oct.: > 5.0
S.V.:<25
S.V.:<10
Increase must not be more than 1 0 PCU above natural conditions
S.V.:<723
Less than 25 percent change from natural conditions
SCO/CHAP3.WPD/003672775
3-45
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Parameter
Fecal Coliform -
No./100mL
Water Quality Standards for Beneficial Uses
< 200/400°
3.4.3.1 Construction Mitigation
Depending on how each alternative is phased for construction will determine some of the
mitigation measures. Assuming each phase of construction actively disturbs more than
5 acres, a National Pollutant Discharge Elimination System (NPDES) permit will be
required. Through the terms and conditions written into the permit, both discharge
limitations and water quality standards are primarily implemented and enforced. The
NPDES permit must be consistent with discharge limitations and water quality standards
established for the receiving waters.

The construction sites for all alternatives will have to be retrofitted with BMP
improvements. These improvements reduce the potential of degrading off site water quality
or watercourses during the short construction period. Examples of some of the BMPs that
will likely be common to all the alternatives are construction of silt barriers (silt fences or
straw bale check dams) to trap sediment, not allowing it to flow to offsite channels. The
contractor will be required to remove the trapped silt and debris to an offsite location before
removing the barriers. Offsite flows will be routed around cut and fill slopes to prevent
contamination of runoff. Bypass channels must be properly designed to convey anticipated
flow volumes and velocities. Construction equipment must be cleaned on a regular basis to
minimize potential runoff contamination from petroleum products. Sediment basins will be
constructed to treat sediment-rich runoff before discharging it offsite to drainage channels.
Construction equipment will be inspected frequently for leaks and repaired immediately
when discovered. All equipment will be fueled and serviced at designated locations in
order to minimize work site contamination. These fueling locations will be located away
from nearby channels, swales, or other features that would quickly facilitate movement in
the event of a spill. Upon completing the construction, all contaminated material (e.g.,
concrete wash water) will be removed and disposed of in accordance with local, regional,
and federal regulations. Temporary sanitary waste facilities will be designed and
developed in a manner that protects both surface and subsurface water resources.

For all the build alternatives, a catch net and temporary spill containment system will be
constructed at the Colorado River or Lake Mead crossing to catch falling debris and collect
contaminants if spilled. For construction of bridge abutments, loose rocks will be scaled
prior to and during excavation work, and netting on the canyon slopes will be used during
blasting to minimize rock fall.

As an additional mitigation measure for the preferred Sugarloaf Mountain Alternative, the
sewer evaporation ponds will have to be relocated and allow for possible wildlife or fencing
improvements.

For the Promontory Point Alternative, to further reduce the chance for water quality
contamination, bridge construction across the lake should be on an accelerated schedule.
Because this is the longest of the three alternative bridges actually crossing live water, it will
require a greater length of time to construct and thereby increase the chance for
contaminating the lake.
3-46 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.4.3.2 Operational Mitigation
Mitigation measures for all alternatives will include properly designed roadway channels
that will resist erosion, construction of energy dissipating structures at all culverts whose
discharge velocity will cause downstream erosion, and building sediment trapping basins
strategically located to maximize sediment removal and still function as a chemical spill
containment structure.

Cut and fill slopes wfll continue to erode unless stabilized using vegetative or mechanical
means. Vegetation will slow surface runoff, help bind soils, reduce raindrop impact and
break up flow patterns. Mechanical means include geotextiles such as matting, retaining
walls, and rock slope protection. Matting and similar products prevent extensive contact
between surface runoff and soil, keeping the soil intact Retaining walls decrease cut and
fill slopes which in turn reduce runoff velocities and erosion potential. Rock slope
protection armors the slope, preventing soil movement.

Discharge in roadside channels and from culverts will erode, transporting sediments
downstream. Slopes along roadside channels and at discharge points from culverts may be
steep, promoting erosion. Therefore, both conveyance features will require some sort of
protection in the form of channel lining, reduced slopes, or energy dissipating structures.
Channel lining may be in the form of rock riprap, and energy dissipating structures will be
designed elements that will break up and reduce discharge velocities.

Over time, the roadway surface will collect contaminants such as oil, grease, soil, and trash.
When it rains, these contaminants will be mobilized and washed from the road surface to
nearby natural and roadside channels. To lessen the impact these contaminants have on
water quality, the runoff will be drained to settling basins, allowing the larger suspended
material to settle. Dissolved contaminants would remain mobile and travel through the
basins to the nearby drainage network. Besides capturing road pollutants, these basins will
also serve to contain chemical spills resulting from vehicle accidents. Each basin will be
designed to contain a certain rainfall runoff volume before allowing discharge. If an
accident occurred, and provided the basins were dry at the time of the accident, the spill
volume in most cases will be accommodated. These settling basins will require periodic
cleaning. Any fences that may be incorporated into the basin design must be compatible
with basin maintenance and function.

In addition, all bridges over live water will have the potential to collect the "first-flush"
runoff volume from the bridge as well as the spill volume that might be generated from a
semi-truck tanker spill. The bridge runoff unit volume is small and could potentially be
captured and transferred to a basin located near the bridge abutment for treatment. Once
the first-flush volume is captured, additional runoff volume will be discharged. In the
event an accident on the bridge resulted in a chemical spill, this first flush system will
normally have the capacity to collect the volume from a typical truck tanker. The roadway
and bridge settling basins will be maintained by NDOT or ADOT, depending on their
location.

At this preliminary stage of design, the location and extent of potential settling basins is
uncertain. If the eventual design causes impacts beyond those cleared in this EIS,
additional studies and National Environmental Policy Act (NEPA) documentation will be
prepared for those areas.
SCO/CHAP3.WPD/003672775 3-47
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.5 Cultural Resources

3.5.1 Affected Environment

Cultural resources are defined as buildings, sites, districts, structures, and objects significant
to history, architecture, archaeology, culture, or science. Significant cultural resources are
those that are listed in or are eligible for listing in the National Register of Historic Places
(NRHP). Listed resources or those resources determined eligible for NRHP listing are often
referred to as "historic properties." The NRHP is the nation's inventory of historic
properties, and NRHP documentation includes a recommendation about whether a
property is significant at the local, State, or national level. The 1992 changes to the National
Historic Preservation Act of 1966 as amended (NHPA) acknowledge mat traditional
cultural properties (TCPs) can be eligible for listing in the NRHP. TCPs are those historic
properties important to American Indian tribes. Hoover Dam itself is a National Historic
Landmark (NHL)—a property designated by the Secretary of the Interior as possessing
national significance in one or more categories: American history, architecture, archaeology,
engineering, and culture. NHLs are also listed on the NRHP.

The NHPA and the Archaeological Resources Protection Act of 1979 (ARPA) are two of the
more important legislative mandates that require Federal agencies to identify cultural
resources within their jurisdictions and consider the effects on those resources as a
consequence of federal "undertakings." Undertakings are those projects planned and
constructed by federal agencies and also include those projects assisted by federal agencies
through funding, technical support, or administrative authorizations (licenses, permits, and
rights-of-way).

The NHPA requires federal agencies to take into account the effect of the undertaking on
any district, site, building, structure, or object that is included in or eligible for inclusion in
the NRHP. Further, the federal agency is required to afford the Advisory Council on
Historic Preservation (ACHP) an opportunity to comment on the undertaking. The ACHP
has promulgated 36 CFR 800 as a set of regulations for federal agencies to follow in
fulfilling the cultural resource consultation and compliance process. The regulations
provide a step-by-step procedure for the entire compliance process, from initial
identification of a resource, through its evaluation, and to final treatment measures
(avoidance, data recovery, etc.) if required for historic properties.

While it is federal policy to avoid or minimize adverse effects to cultural resources when
planning, constructing, and/or assisting federal projects, in some cases it is impossible to
avoid disturbing or destroying some cultural resources if an authorized development is to
be implemented. In such instances, it is federal policy to recover the information embodied
in those resources through historical, archaeological, and ethnographical study before the
project begins. Other federal policies that may be applicable to the consideration of cultural
resources potentially affected by the project include EO13007 and the Native American
Graves Protection and Repatriation Act of 1990 (NAGPRA).

Because the project is a federal undertaking, consultation with Indian Tribes is mandated by
several policies, laws, and regulations including EO 13007, ARPA, NAGPRA, NHPA, and
NEPA. Consultation is recognized as the most effective means of determining if TCPs are
present within a project area.

All of the historic properties in the area of potential effects have been assessed in terms of
their eligibility (or lack thereof) for listing in the NRHP. With the exception of the recently

3-48 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

discovered prehistoric archaeological sites documented during 1998 and 1999, additional
historic sites relating to Hoover Dam, and the eligible TCP site, the NRHP eligibility status
of all of the historic sites and features in the project area was determined through earlier
consultations (1991 to 1993) between the former lead agency (Reclamation) and the Arizona
and Nevada SHPOs.

Preliminary consultations between Reclamation and the ACHP were conducted in 1991
with the result that the ACHP found the Gold Strike Alternative to be the least likely to
produce adverse effects on the Hoover Dam NHL. ACHP urged Reclamation to refine its
analyses and provide the DEIS for their review. FHWA provided ACHP with the DEIS and
has consulted with ACHP on the preferred alternative. The majority of the effect
determinations discussed in this DEB were made by the SHPOs during the 1991 to 1993
consultations with Reclamation.

After a 4-year hiatus and transfer of lead agency responsibility from Reclamation to FHWA,
formal consultations with the two SHPOs were reinitiated in October 1997. These
consultations continued through both the NEPA process and the Section 106 process. Prior
to cessation of the project study in 1993, Reclamation had not yet initiated consultations
with affected Indian tribes. FHWA started tribal consultations through implementation of
an intensive program of field trips and elder interviews that were conducted in late
May/early June 1998. Beginning in December 1999, FHWA formally requested the
participation of interested Native American tribal representatives in a series of
government-to-government consultation meetings to facilitate identification and treatment
of traditional cultural properties for the Hoover Dam Bypass. NPS and Reclamation
cultural resource staff assisted FHWA in identifying the appropriate tribal representatives
to involve in the consultation process. Consultation meetings involving 12 Native
American tribes, FHWA, NPS and Reclamation occurred during completion of the NEPA
and Section 106 process in 2000, specifically on January 11, March 30, May 8, August 15 and
16, and November 15. These meetings will continue after approval of the Record of
Decision, through design and construction of the Hoover Dam Bypass.

3.5.1.1 Surveys, Tribal Interviews, and Literature Reviews
Prior to mid-1993, Reclamation conducted cultural resources inventories as part of the
preparation of the Hoover Dam Bypass DEIS (Queen 1992 and White 1993a,b). These
surveys resulted in the identification and recordation of numerous historic features, several
of which are associated with the construction of Hoover Dam. Except for a single rock
feature, no prehistoric Native American sites were identified by Reclamation. Literature
sources revealed 44 cultural features within the area, and 42 of the 44 features are associated
with constructing, operating, and maintaining Hoover Dam. Thirty-three of the features are
not considered individually eligible for listing in the NRHP; however, they may contribute
to a potential historic district that focuses on constructing, operating, and maintaining
Hoover Dam.
A large prehistoric archaeological site was discovered in November 1997. An
archaeological survey of the three build alternatives was conducted in March 1998.
Following FHWA standards, an Area of Potential Effects (APE) was established for the
three build alternatives. The APE, defined as all ground surface 200 feet to each side of the
staked centerline, was intensively surveyed by a team of archaeologists walking transects
parallel to the centerline, spaced a maximum of 20 meters. When cultural materials were
found, the location was flagged, and the archaeological sites were formally recorded. The
survey resulted in the discovery and recordation of five prehistoric archaeological sites on
the Arizona side (including the site found in 1997). FHWA, in consultation with the
SCO/CHAP3.WPD/003672775 3-49
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Arizona SHPO, determined that these five sites are not eligible for the National Register
(see further discussion of sites 14:21 and 14:22 below). The Arizona State Museum assigns
site registration numbers for Mohave County, Arizona, and includes the partial descriptor
"NV" in its registration numbers.
AZ:NV:DD:14:21
Sugarloaf Mountain (in the APE)
AZ:NV:DD:14:22
Sugarloaf Mountain (in the APE)
AZ:NV:DD:14:23
Promontory Point (in the APE)
AZ:NV:DD:14:24
Promontory Point (outside APE)
AZ:NV:DD:14:25
Promontory Point (in the APE)
Gypsum Period (5000-2000 B.P.) or Late
Prehistoric (750 B.P-Contact)
Unknown prehistoric time period

Unknown prehistoric time period

Unknown prehistoric time period
The May-June 1998 site visits and field interviews with tribal elders, conducted for FHWA
by the University of Arizona, resulted in completion of an ethnographic study report for the
Hoover Dam Bypass Project in December 1998 (FHWA, October 2000a). That report
included preliminary findings, summarized in the DEIS, indicating the presence of
potentially significant traditional cultural properties in the vicinity of the bypass project.

After identification of Sugarloaf Mountain Alternative as the preferred alternative,
following circulation of the DEIS in November 1998, NFS and Reclamation directed FHWA
to conduct a detailed historic resources survey to update and expand the sites previously
recorded by Reclamation, as well as additional intensive surface mapping and
documentation of archaeological sites 14:21 and 14:22 located in Arizona. Both the historic
and archaeological surveys were scoped to provide additional documentation to address
National Register eligibility of sites in the APE of the preferred alternative. Those
additional investigations, conducted during March and June 1999, resulted in completion of
a supplemental archaeological resources survey report (FHWA, April 2000) and a historic
resources survey report (FHWA, August 1999) for the Sugarloaf Mountain Alternative.

The 1999 archaeological resources survey report concluded that sites 14:21 and 14:22 were
not eligible for the National Register, because after detailed surface inspection and
mapping, it was determined the sites lacked information important in the prehistory of the
areas. The historic resources survey report resulted in identification of seven additional
National Register eligible historic properties relating to construction and operation of
Hoover Dam. Those reports and the December 1998 ethnographic study (FHWA, October
2000a) were submitted by FHWA to the Arizona and Nevada SHPOs in August 1999 with a
request for concurrence in determinations of National Register eligibility for the affected
historic properties.

The Nevada and Arizona SHPOs commented back to FHWA, in September and October
respectively, concurring in the determinations of National Register eligibility for most of the
historic properties documented by FHWA. However, the Nevada SHPO requested that
FHWA conduct an ethnohistoric study to provide documentary context for assessing the
potential traditional cultural properties identified by the tribal elders during the 1998 field
interviews, and that FHWA commence formal government-to-government consultation

3-50 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

with affected Native American tribes concerning the significance and National Register
eligibility of the potential traditional cultural properties in the project area. The Arizona
SHPO also requested further consideration of potential TCPs in the area, as well as
additional information on archaeological sites 14:21 and 14:22, within a broader historic and
ethnographic context, to more fully evaluate the potential National Register eligibility of
these sites. (See Appendix C and Volume II for copies of all pertinent FHWA, SHPO, and
Native American tribal correspondence relating to cultural resources.)

At the first meeting between the Native American tribal representatives and the federal
agencies, held on January 11,2000, the tribes requested that the 1998 ethnographic studies
be expanded to other locations and include additional tribes and elders. As a result, the
University of Arizona conducted additional site visits and interviews during May 2000.
The resulting report (FHWA, October 2000a), coupled with the eihnohistoric assessment
report (FHWA, October 2000b), provided documentation supporting a determination by
FHWA and the SHPOs that the Gold Strike Canyon and Sugarloaf Mountain TCP is eligible
for the National Register of Historic Places (FHWA, October 2000c). The National Register
eligible TCP boundaries include archaeological site 14:21 (FHWA, April 2000), which
Reclamation noted in an October 6,2000, letter to FHWA supporting the TCP eligibility,
"should be considered to contribute to the eligibility of the larger Gold Strike Canyon and
Sugarloaf Mountain TCP" (see Appendix C, October 6,2000, Reclamation letter).

3.5.1.2 Archaeological Context
The prehistory of the proposed project area covers the time period from about 12,000 years
before present (B.P.) (B.P. being before 1950) to the time of initial European contact in
A.D. 1600, and is divided into five periods: Lake Mohave (12,000 to 7000 B.P.), Pinto (7000
to 5000 B.P.), Gypsum (5000-2000 B.P.), Saratoga Springs (2000 to 800 B.P.), and Late
Prehistoric (750 B.P.-Contact) (Ezzo et al., 1995).

Lake Mohave Period (12000 to 7000 B.P.). Evidence of Paleo-Indian occupation in the vicinity
of the proposed project is lacking. Either the material remains were quickly covered over,
or they were rapidly scattered about or washed away from their original location,
effectively destroying the site. The Paleo-Indian culture gave rise to a series of more
localized cultural manifestations known as the Archaic, represented in the proposed project
area by the Pinto and Gypsum periods.
In general, the Archaic represents a period of hunting and gathering characterized by
reduced mobility, more localized adaptations, and greater diversity of tool kits. Most
recorded sites from this time period are surface finds.

Pinto Period (7000 to 5000 B.P.). The Pinto period is defined by the presence of the Pinto
complex—an assemblage characterized by leaf-shaped knives, scrapers, and projectile
points. Pinto settlement in the proposed project vicinity was centered around water
sources, particularly drainages and remnant pluvial lakes. Settlement focused on valley
floors, favoring lowland, well-watered habitats. Hunting continued to be an important
dietary component, but milling implements appeared for the first time, indicating a greater
reliance on, and orientation toward, plant food resources than during the preceding Lake
Mohave period (Ezzo et al., 1995).

Gypsum Period (5000 to 2000 B.P.). The Gypsum period represents a continuation of the pre-
agricultural Pinto foraging lifestyle. Gypsum sites evidence greater use of milling
implements, resource diversification, and greater emphasis on plant and seed processing.
Gypsum period assemblages are characterized by a variety of projectile points. Other tools
SCO/CHAP3.WPD/003672775 3'51
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

include leaf-shaped points, flake scrapers, choppers, hammerstones, rectangular-based
knives, manos, mortars, and pestles.
The Gypsum period appears to have been a time of increased human activity in the
proposed project area. Groups moved through a range of diverse ecological zones that
included mountains, riverine habitats, and other lowland areas, to hunt, collect, and process
seeds and wild plants (Ezzo et al., 1995). Compared to previous periods, there are a greater
variety of site types: rockshelters and caves were utilized, and open-air sites included
camps and specialized activity areas. Bighorn sheep became a significant food source, and
small game, which was abundant in the riparian communities or well-watered areas, was
also hunted (Ezzo et al., 1995).

Saratoga Springs Period (2000 to 800 B.P.). The Saratoga Springs period exemplifies the
influence of the Anasazi in the proposed project area. It can be divided into four phases:
Moapa phase (1650 to 1450 B.P.), Muddy River phase (1450 to 1250 B.P.), Lost City phase
(1250 to 850 B.P.), and Mesa House phase (850 to 800 B.P.). The Moapa phase corresponds
to the Basketmaker II period of the Colorado Plateau, a time when pithouse villages made
their first appearance. The Moapa phase represents the beginning of the transition from a
foraging to a sedentary, agricultural way of life in the northern Southwest (Ezzo et al.,
1995).
The Muddy River phase corresponds to the Basketmaker HI period on the Colorado Plateau
and is characterized by the introduction of ceramics and the bow and arrow. Settlements
consisted of small numbers of randomly arranged pithouses and food storage cists. The
introduction of ceramics and the bow and arrow had significant effects on hunting and
storage capabilities. This introduction reduced the use of food storage cists in caves for
storing seeds and plant materials for extended periods of time; it also reduced the need for
woven baskets for use in cooking, storage, and water transport (Ezzo, et al., 1995).
The Lost City phase corresponds to the Pueblo I and the early and middle stages of the
Pueblo II period on the Colorado Plateau. There was a shift from subterranean or semi-
subterranean structures to surface structures, generally with associated storage facilities.
The Mesa House phase corresponds to the late Pueblo II period on the Colorado Plateau
and represents the final period of Anasazi settlement in the Las Vegas Valley and
neighboring areas. The primary distinguishing characteristic of the Mesa House phase is
the new types of decorated ceramics. Agriculture continued to be an important component
of subsistence, but wild foods continued to be significant (Ezzo et al., 1995).
Ezzo et al. (1995) discuss the two recent models that attempt to explain Virgin Anasazi
expansion and demise. Rafferty's model (Rafferty 1984,1990a,b) relies on the concept of
world-systems theory to buttress his argument that Anasazi expansion into the Las Vegas
Valley was driven by population increase and the need to secure valuable resources for
exchange into Chaco Canyon (the leaders of which were sending such goods to the heart of
the Toltec empire in central Mexico). Lyheis's (1990,1992a,b) model adheres closely to
available data and recognizes the complexity of human systems and behavior to address the
issue of Anasazi expansion and retreat.

Late Prehistoric Period (750 B.P.-Contact). Late prehistoric occupation in the project area is
characterized by artifact assemblages that include Owens Valley Brownware ceramics, a
variety of projectile points, large triangular knives, incised stones, steatite beads, slate
pendants, shell beads, unshaped manos and metates, and mortars and pestles. These
artifacts describe the basic lifestyle of a foraging people who may have practiced
horticulture on a small scale and lived in small, mobile groups that exploited well-watered

3-52 SCO/9820800.WPD/003672775
-------
_ CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

and upland environments. These assemblages provide good evidence for the abandonment
of the region by the Anasazi and the arrival of the Southern Paiute (Ezzo et al., 1995). Ezzo
et al. (1995) also reviewed the complex issues surrounding the nature and timing of the
entry of the Paiutes (or their direct ancestors) into the region— either as early as several
thousand years ago or as recently as a thousand or fewer years ago.

Southern Paiute sites tend to consist of surface artifact scatters often associated with hearths
or arrangements of fire-cracked rock. Caves and rock shelters were preferred locations for
occupation, and petroglyphs occasionally occur on rock shelter walls or on standing
boulders— -an attribute of the Patayan tradition (Ezzo et al., 1995). According to Ezzo et al.
(1995) the Patayan influence in the region at mis time is more significant than in any
previous period; the pattern of interaction between Patayan and Anasazi and Patayan and
Paiute becomes a common occurrence after A.D. 1000 in the Arizona Strip and adjacent
areas to the west. The Patayan subsistence and settlement is similar to that of the Southern
Paiute - mobility and a mixed subsistence base in a wide range of ecological zones
including floodplains, valleys, and uplands. Fragile-pattern sites, primarily an aspect of the
Patayan cultural tradition, occur in the region as well. These sites are created by the
deliberate or incidental removal of desert pavement from the surfaces of benches,
piedmonts, or relict river terraces to create intaglios, earth figures, or geoglyphs in linear,
abstract, zoomorphic, and anthropomorphic shapes. Another feature common to Patayan
sites along the lower Colorado River are rocks deliberately shaped into a number of
patterns (circles and lines). Rock rings (circles) may have functioned as hearths, sleeping
areas, or windbreaks, while linear alignments probably functioned as directional markers
that pointed travelers toward a particular locality.

Late prehistoric activity in the area represents a time of rather dispersed, small mobile
groups occupying habitats and landforms that were previously utilized by the Virgin
Anasazi. Subsistence was maintained through a combination of farming the floodplains of
the Virgin and Muddy Rivers and probably the larger washes, and exploiting a wide range
of ecological zones for wild plant and animal resources (Ezzo et al., 1995).

Historic Period (Contact-Hoover Dam Construction). The earliest Euro-American exploration
of the Colorado River dates from the mid-1500s. The Colorado River was discovered and
explored in 1540 by the Alarcon, Diaz, and Cardenas expeditions. In 1604-05, Ornate led
another Spanish expedition to the mouth of the Little Colorado River, then followed the
river to the Gulf of California. Throughout the 1700s, the Spanish conducted several
expeditions into the area including explorations by Father Sedelmeyer (1744), Father Garces
(1771 and 1775-76), Father Anza (1774), and Father Escalante (1776).

Trappers began to explore the area in the mid-1800s. In 1826, James Puttie became the first
white to ascend the Colorado River from its mouth to the Rocky Mountains and in the same
year, Jedediah Smith also explored the Colorado River, beginning at its confluence with the
Virgin River to the area around Needles, California. From 1846 to 1860, War Department
survey parties explored and mapped the Lower Colorado River. In 1857-58, Lt. J.C. Ives
completed the first detailed exploration of the Colorado River as he traveled by steamboat
from the mouth of the river to a point in the vicinity of Las Vegas Wash. When the Civil
War ended, survey and exploration resumed in the Colorado River basin.

Regulation of the Colorado River demanded federal involvement because the river had
navigable status (the government had jurisdiction over its control and use) and the river
was international (actions affecting water supply required agreement with Mexico). In
addition, the Colorado flowed through several states with different and sometimes
SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAI CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

contradictory water needs and interests. To reach agreement on the disposition of water
rights to the Colorado River, the states of Colorado, California, Nevada, Arizona, Utah,
Wyoming, and New Mexico formed the League of the Southwest in 1919. The league urged
the federal government to help develop the water resources of the Colorado River basin. In
1921, Congress authorized the states to form a compact to achieve agreement on equitable
water distribution. Not all states agreed to the terms, however, and the compact was never
ratified.

The states did not reconcile their differences until Congress enacted the Boulder Canyon
Project Act in 1928. Six of the seven states had to ratify the compact in order for the Act to
take effect; it was ratified in 1929 with only Arizona abstaining. The compact provided for
equitable water distribution and ensured Mexico's rights to use the waters of the Colorado
River system. It also acknowledged that domestic, agricultural, and hydropower uses
should take precedence over navigation.

The Boulder Canyon Project Act authorized construction of a 20,000,000 acre-foot capacity
reservoir and dam in Boulder Canyon and a high-line canal from Laguna Dam to the
Imperial Valley. By 1920, all alternative potential dam sites had been eliminated except for
those in Boulder Canyon and Black Canyon, near Las Vegas. Site D in lower Black Canyon
was eventually selected as the dam site. Designs for a dam had been developed during the
1920s, and final designs for a massive arch-gravity dam were approved by the Colorado
River Board on November 19,1932.

The design called for the dam to have a base thickness of 660 feet, a crest width of 45 feet,
and a crest length of 1,282 feet. The dam would create the largest reservoir in the world at
that time, approximately 115 miles long, with a maximum depth of 590 feet, covering
227 square miles, with a capacity of 32,000,000 acre-feet. In 1931, a railroad was constructed
from Boulder City to the Hoover Dam construction site for moving materials and
equipment. Construction began in November 1932, and the first concrete was poured in
June 1933. By February 1935, enough of the dam was completed to begin controlling the
flow of the Colorado River and creating the reservoir. Secretary of the Interior Harold Ickes
officially accepted the dam and power plant as complete in March 1936, almost 2 years
ahead of schedule. President Franklin Roosevelt dedicated the dam on September 30,1935,
and the reservoir was named Lake Mead in February 1936 in honor of Dr. Elwood Mead,
former Commissioner of Reclamation.

3.5.1.3 Traditional Cultural Properties
The University of Arizona (U of A) conducted ethnographic investigations in 1998 and 2000
to support the preparation of the FJS. Since TCPs may be eligible for NRHP listing in
accordance with recent amendments to the NHPA, U of A was scoped to conduct a
program of detailed field interviews with tribal representatives ("elders") to assist FHWA
determine the presence/absence of TCPs and to facilitate future project consultations
between FHWA and the various Indian tribal governments (see Sections 3.5.1 and 3.5.1.1).

The major finding of the ethnographic investigation is that the overall project area lies
within a National Register-eligible TCP. FHWA recommended the site as an eligible TCP,
and the SHPOs, Reclamation, and NFS concurred. This property encompasses a geographic
area that includes Gold Strike Canyon on the Nevada side and Sugarloaf Mountain on the
Arizona side. Among many statements by the elders, the participating tribal
representatives believe:

| • Sugarloaf Mountain and the Gold Strike Hot Springs are on "The Salt Song Pathway."
3-54 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Amongst the Mohaves, Sugarloaf Mountain is linked to the Origin Mountain,
Avikwa'ame.
• Gold Strike Canyon Hot Springs and Sugarloaf Mountain are connected to Gypsum
Cave and the Creator.
• Sugarloaf Mountain is marked by healing stones used for doctoring. |
• Ceremonial clearings on Sugarloaf Mountain were used for vision quests and dancing. |
• Gold Strike Canyon and Sugarloaf Mountain are near a traditional turquoise mine. |
• A petroglyph on top of Sugarloaf Mountain is a universal symbol and a trail marker. |
• The Gold Strike Canyon Hot Springs are sacred, used for healing and purification. |

3.5.2 Environmental Consequences

3.5.2.1 Historical
Eighteen historic sites or features previously identified by Reclamation (Queen, 1992, and
White, 1993a, b) would be affected or potentially affected by the three alternatives: Hoover
Dam - 26-CK-3916, the Kingman Switchyard - AZ:DD:14:1, Waste Tailings (AZ) -
AZ:NV:DD:14:15, Old Construction Road and Test Borings (AZ) - AZ:NV:DD:14:16, World
War H Bunker (AZ) - AZ:NV:DD:14:18, the Wooden Ladders (NV) - 26-CK-4734, the
Cantilevered Walkway - 26-CK-4742, the Tunnel - 26-CK-4748, Tailings (NV) - 26-CK-4750,
the Old Government Railroad grade (Reclamation lands) - 26-CK-4751, Building
Foundations (NV) - 26-CK-4752, the Diversion Channel - 26-CK-4753, a Retaining Wall -
26-CK-4754, a Trash Scatter - 26-CK-4763, some elements of the Electrical Power
Transmission Switchyard (the Nevada State Switchyard, the M.W.D. Switchyard, and the
Southern California Edison Switchyard) - 26-CK-4765, the Scenic Overlook (NV) - 26-CK-
4766, Transmission Towers and Lines (NV) - 26-CK-5180, and an Old Construction Road
(AZ)-AZF:2:87.
Seven additional historic and cultural properties identified by FHWA after circulation of the
DEIS would be affected or potentially affected by the proposed project: the Hoover Dam
Transmission Towers in Arizona - AZ:NV:DD: 14:29, Old Arizona U.S. Highway 93 Segment
in APE - AZ:NV:DD:14:30, Sugarloaf Mountain Survey Station - AZ:NV:DD:14:31, Stone
Gates and Lower Portal Access Road (NV) - 26-CK-5789, U.S. 93 Switchback Segment in
Nevada - 26-CK-5790, the Arizona-Nevada Switchyard (NV) - 26-CK-5792, and the Gold
Strike Canyon and Sugarloaf Mountain TCP. (See FHWA, August 1999, for historic
properties, and Section 3.5.1.3 along with FHWA, 2000a, and FHWA, October 2000b, for
detailed documentation on the TCP; also see Appendix C, August 27,1999, and October 12,
2000, FHWA Determination of Eligibility letters to SHPOs.)
Promontory Point Alternative. In June 2000, FHWA applied the criteria of adverse effect and
determined in consultation with the Nevada and Arizona SHPOs that the Promontory Point
Alternative would have an adverse effect on the Hoover Dam National Historic Landmark
because the bypass project would introduce visual elements that diminish the integrity of
the property's significant historic features and setting, although it would not cause any
physical damage to the dam complex. An adverse effect is found when a project may alter,
directly or indirectly, the characteristics of a historic property that qualify the property for
inclusion in the National Register in a manner that would diminish the integrity of the
property's location, design, setting, materials, workmanship, feeling, or association. Section
110(f) of the NHPA requires that the Agency Official, to the maximum extent possible,
undertake such planning and actions as may be necessary to minimize harm to any NHL
SCO/CHAP3.WPD/003672775 3-55
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

that may be directly and adversely affected by an undertaking (36 CFR 800.10); however,
FHWA and NFS have determined that the historic views of the dam would be adversely
affected and cannot be mitigated. The Promontory Point Alternative would enhance
protection of the physical features of the dam by removing trucks from the dam and
thereby eliminating the potential for hazardous material spills and large vehicle collisions
with dam facilities.
It was also determined, based on previous findings by Reclamation (Queen, 1992, and
White, 1993) and recent investigations by FHWA (FHWA, August 1999), that the
Promontory Point Alternative would have an adverse effect on the following additional
historic properties eligible for the National Register for their association with the
construction and operation of Hoover Dam or as contributing elements to the NHL (see
above): Old Arizona U.S. Highway 93 Segment in APE, Old Government Railroad Grade
(NV), Building Foundations (near Nevada bridge abutment), the Diversion Channel and
Retaining Wall (NV), the Nevada State Transmission Switchyard (NV), and the historic
Transmission Towers and Lines in Nevada (see Appendix C, June 6,2000, FHWA
Determination of Eligibility and Effect letters to SHPOs). The Promontory Point Alternative
would also have an adverse effect on the Gold Strike Canyon and Sugarloaf Mountain TCP
(FHWA, October 2000a).
The Old Government Railroad grade (Reclamation lands) would be partially affected by the
Promontory Point Alternative. The diversion channel and retaining wall are not
individually eligible for listing in the NRHP, but are eligible as contributing elements to a
potential Hoover Dam historic district under NRHP, criterion "C." Both may suffer
possible direct impact as a result of Promontory Point construction.
The Nevada State electric power transmission switchyard is not individually eligible, but is
eligible as a contributing element to a potential district under NRHP criterion "C." The
Promontory Point construction could produce both direct and indirect impacts, and partial
demolition may be required.
Sugarloaf Mountain Alternative (Preferred Alternative), in June 2000, FHWA applied the
criteria of adverse effect and determined, in consultation with the Nevada and Arizona
SHPOs, that the Sugarloaf Mountain Alternative would have an adverse effect on the
Hoover Dam NHL because the bypass project would introduce visual elements that
diminish the integrity of the property's significant historic features and setting, although it
would not cause any physical damage to the dam complex. However, FHWA and NFS
determined that the preferred alternative would not detract from the historic views of the
dam as would the Promontory Point Alternative. The Sugarloaf Mountain Alternative
would enhance protection of the physical features of the dam by removing trucks from the
dam and thereby eliminating the potential for hazardous material spills and large vehicle
collisions with dam facilities.
It was also determined, based on previous findings by Reclamation (Queen, 1992, and
White, 1993) and recent investigations by FHWA (August 1999), that the Sugarloaf
Mountain Alternative would have an adverse effect on the following additional historic
properties eligible for the National Register for their association with the construction and
operation of Hoover Dam or as contributing elements to the NHL (see above): Kingman
Switchyard (AZ), Transmission Towers and Lines in Arizona, Old Arizona U.S. Highway 93
Segment in APE, Old Government Railroad Grade (NV), Transmission Towers and Lines in
Nevada, Stone Gates and Lower Portal Access Road (NV), U.S. 93 Switchback Segment
(NV), and the Arizona-Nevada Switchyard (NV) (see Appendix C, June 6,2000, FHWA
Determination of Eligibility and Effect letters to SHPOs); however, the Kingman Switchyard
3-56 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

and the U.S. 93 Switchback Segment would not be physically damaged, but only indirectly
affected by a change in the setting. The Sugarloaf Mountain Alternative would also have an
adverse effect on the Gold Strike Canyon and Sugarloaf Mountain TCP (FHWA,
October 2000a).
The Kingman Switchyard is not individually eligible, but it is eligible as a contributing
element to a potential district. Construction could produce indirect effects on its visual and
historic setting. The Old Government Railroad grade (Reclamation lands) would be
partially affected by construction. Construction could produce both direct and indirect
impacts on the Arizona-Nevada Switchyard, and modification or demolition may be
required.
Gold Strike Canyon Alternative. In 1991, during early consultation on the bypass project,
Reclamation along with NFS and the Nevada and Arizona SHPOs reviewed the effects of
the Gold Strike Canyon Alternative and concluded that it would have "no adverse effect" on
the Hoover Dam National Historic Landmark because a bridge at this location "competes
the least with the Landmark" (see Appendix C, October 2,1991, Reclamation meeting
notes). The Gold Strike Canyon Alternative would not cause any physical damage to the
dam complex and would enhance protection of the physical features of the dam by
removing trucks from the dam, thereby eliminating the potential for hazardous material
spills and large vehicle collisions with dam facilities.
It was also determined, based on previous findings by Reclamation (Queen, 1992, and
White, 1993) and recent investigations by FHWA (FHWA, August 1999), that the Gold
Strike Canyon Alternative would have an adverse effect on the following historic properties
eligible for the National Register for their association with the construction and operation of
Hoover Dam or as contributing elements to the NHL (see above): Arizona Waste Tailings,
Old Construction Road and Test Borings (AZ), Old Arizona U.S. Highway 93 segment in
APE, Wooden Ladders (NV), and the Waste Tailings in Nevada (see Appendix C, June 6,
2000, FHWA Determination of Eligibility and Effect letters to SHPOs). The effects on the
Tunnel (NV) and Cantilevered Walkway (NV) properties were undetermined by
Reclamation. The Gold Strike Canyon Alternative would also have an adverse effect on the
Gold Strike Canyon and Sugarloaf Mountain TCP (FHWA, October 2000a).
The waste tailings, cantilevered walkway, tunnel, and the Nevada tailings are not
individually eligible, but are eligible as contributing elements to a potential district. The
Nevada tailings would suffer direct impact from Gold Strike Canyon construction, while
the walkway could suffer partial or direct impact. The tunnel could provide construction
access to the Gold Strike Canyon worksite if it were enlarged to accommodate heavy
equipment. The Arizona tailings could also suffer partial impact from Gold Strike Canyon
construction.

3.5.2.2 Archaeological
Five prehistoric archaeological sites were recorded during investigation of the proposed
project alternatives. None of these sites were found to be eligible for the National Register.
Four of the five sites are within the APE (ASM NV:DD:14:21, -22, -23, and -25) while one
appears to be outside the APE (ASM NV:DD:14:24). All four sites within the APE would
likely be impacted, while the site outside the APE might be impacted without fencing.
Promontory Point Alternative. Two prehistoric archaeological sites were recorded within the
APE of the Promontory Point Alternative (ASM NV:DD:14:23 and -25), and one site was
recorded just outside the APE (ASM NV:DD:14:24). These three sites were found to be
ineligible for NRHP listing.
SCO/CHAP3.WPD/003672775 3-57
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

| Sugarloaf Mountain Alternative (Preferred Alternative). Two prehistoric archaeological sites
lie within the APE of the Sugarloaf Mountain Alternative. Although not individually
| eligible, one site is a contributor to the eligible TCP (ASM NV:DD:14:21); the other is not
(ASMNV:DD:14:22).

Gold Strike Canyon Alternative. No archaeological sites were detected in those portions of
the Gold Strike Canyon Alternative APE that were surveyed in March 1998.

3.5.2.3 Traditional Cultural Properties
As a result of government-to-government consultation and as indicated above, the
ethnographic study (FHWA, October 2000a) indicates that an NRHP-eligible TCP is present
in the project area, and construction of any of the three build alternatives would adversely
affect this property.

3.5.2.4 Construction Impacts

Promontory Point Alternative. Construction of the Promontory Point Alternative would have
an adverse effect on the historic visual setting of Hoover Dam. FHWA and NFS
determined that the adverse effect on the historic views of the dam could not be mitigated.
Segments of the Old Government Railroad grade within Reclamation jurisdiction would be
adversely affected; however, NPS is in the process of developing an agreement with NDOT
to convert this historic railroad grade to a bicycle/pedestrian trail (see Section 3.8,
Recreation Resources). A part of the diversion channel and a small segment of the retaining
wall would be destroyed by construction. The northernmost electrical power transmission
switchyard would be partially or totally destroyed, and transmission towers in Nevada
would be relocated. The Old Arizona U.S. Highway 93 segment would be directly
impacted.
The two ineligible prehistoric archaeological sites within the APE would likely be destroyed
during construction.
The Promontory Point Alternative would also directly impact approximately 14 acres from
the northeastern portion of the Gold Strike Canyon and Sugarloaf Mountain TCP on the
Arizona side.
Sugarloaf Mountain Alternative (Preferred Alternative). Construction of the Sugarloaf
Mountain Alternative would have an adverse effect on the historic visual setting of Hoover
Dam; however, this effect can be mitigated. Several of the historic transmission towers and
lines in Arizona and Nevada will require relocation for construction of the bypass roadway
and bridge. A portion of the abandoned Arizona U.S. 93 segment in the APE will be
covered by construction of a bridge over Kingman Wash. The bypass may directly impact
the stone gates, but would not affect the lower portal access road near the Reclamation
warehouse on the Nevada side. A segment of the Old Government Railroad grade within
Reclamation jurisdiction will be directly affected (see Section 3.8, Recreation Resources).
The Arizona-Nevada Switchyard may be modified or fully demolished.
Two individually ineligible prehistoric archaeological sites are located in the APE. One site
would be partially destroyed during construction, and the other site would be completely
destroyed during construction (see Section 3.5.2.2).
The Sugarloaf Mountain Alternative would also directly impact approximately 22 acres
from the northern portion of the Gold Strike Canyon and Sugarloaf Mountain TCP on the
Arizona side. The preferred alternative alignment traverses along the base of Sugarloaf
Mountain, approximately 700 feet north and 200 feet below the mountain top. The area
3-58 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

where the bypass crosses the TCP is already disturbed by transmission lines and towers, a
switchyard and other power facilities, maintenance roads, and sewer evaporation ponds.

Gold Strike Canyon Alternative. Construction of the Gold Strike Canyon Alternative would
have no adverse effect on the historic visual setting of Hoover Dam. The historic waste
tailings on the Arizona side would be partially destroyed by project construction. The Old
Arizona U.S. 93 highway segment would be directly impacted. The cantilevered walkway
and tailings on the Nevada side would be partially destroyed. The tunnel could be
substantially altered if it is enlarged to accommodate access by large, heavy equipment
needed for construction.

The Gold Strike Canyon Alternative would also directly impact approximately 51 acres
from the entire length of the Gold Strike Canyon and Sugarloaf Mountain TCP. Of the three
build alternatives, the Gold Strike Canyon alignment would have the most substantial
impact on the TCP, physically damaging large, presently undisturbed portions of most of
Gold Strike Canyon on the Nevada side and the southern flank of Sugarloaf Mountain on
the Arizona side.

All Alternatives, The ethnographic study indicates that the project area lies within a TCP.
Thus, all three build alternatives impact the TCP. According to the tribal representatives
(FHWA, October 2000a), specific impacts might include:
• Tremendous amounts of ground disturbance (especially at Gold Strike Canyon).
• Intrusion and interference with ceremonies, songs, or trail systems.
• Scaring away rams and damaging artifacts and archaeological sites during construction
and project operation.
• Construction and project operation would destroy the whole site, the scenery, and the
culture related to it. The bridge could destroy artifacts and aesthetic setting.
• Any kind of construction would damage Indian sacred land/country.
• Dynamiting rock and bulldozing may injure workers and tourists (construction killed a
Pahrump Paiute Hoover Dam project worker in 1935).
• Construction would trample ruins and deplete the herds of mountain sheep.
• Construction would damage mountain sheep trails to water. Undiscovered rock
writings might be destroyed.
• There will be more pollution and public access, more vandalism and destruction.
• Known and unknown cultural resources would be destroyed.
• There would be a lot of damage, especially on Sugarloaf Mountain.

• Construction would hurt the rocks.

3.5.2.5 Operational Impacts
Promontory Point Alternative. Construction of the Promontory Point Alternative would have
an adverse effect on the historic visual setting of Hoover Dam, which would continue if the
Promontory Point Alternative were constructed. Because segments of the Old Government
Railroad grade within Reclamation jurisdiction would be destroyed, there would be no
operational impacts to this feature. Similarly, those portions of the diversion tunnel and
retaining wall that would be destroyed by construction would likely not experience further

SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMEOTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM _

impact resulting from project operation. The northernmost electric power transmission
switchyard, which would be partially or totally destroyed, would not likely experience
further impact from project operations. Operation of the Promontory Point Alternative
would affect the historic setting of the World War n Bunker in Arizona and the old building
foundations (near the bridge abutment) and remaining transmission towers in Nevada.

Since construction would probably destroy one prehistoric archaeological site and may
likely destroy another, the potential effects of project operation would be moot. If one of
the sites escapes destruction or damage from road construction, it could still be subject to
operational impacts from the new roadway. Without fencing, destructive impacts during
operation could take the form of off-road-vehide use adjacent to the roadway, or illegal
collection of artifacts facilitated by easy road access. None of these archaeological sites are
eligible for the NRHP.

Sugarloaf Mountain Alternative (Preferred Alternative}. Construction of the Sugarloaf
Mountain Alternative would have an adverse effect on the historic visual setting of Hoover
Dam; however, this impact can be reduced by implementation of mitigation measures in the
PA. The anticipated visual impacts expected to affect the Kingman Switchyard and the
Sugarloaf Mountain Survey Station can be mitigated. The Arizona-Nevada Switchyard, if
not demolished, would be visually impacted from project operations. The U.S. 93
switchback segment in Nevada and the remaining historic transmission towers also would
be visually impacted from project operations.

Operation of this alternative could produce impacts to a prehistoric archaeological site in
addition to its partial destruction resulting from construction. Without planned fencing,
destructive impacts during operation could take the form of off-road-vehicle use adjacent to
the roadway or illegal collection of artifacts facilitated by easy road access to the site if there
is no access control fencing. This site is a contributing element of the TCP.

Gold Strike Canyon Alternative. Construction of the Gold Strike Canyon Alternative would
have no adverse effect on the historic visual setting of Hoover Dam. Project operation
would also have no adverse effect on the historic visual setting of Hoover Dam. The waste
tailings on the Arizona site that would be partially destroyed by project construction, and
the cantilevered walkway and tailings on the Nevada side that would also be partially
destroyed, would not likely experience any further impact resulting from project operation.
The tunnel, which might be substantially altered if it is enlarged to accommodate access by
large, heavy equipment needed for construction, would not likely experience further impact
from project operations. Because no archaeological sites were identified in or adjacent to
this alternative, no operational impacts are expected.

All Alternatives. Operational impacts to the TCP would include traffic noise, exhaust
emissions, and a change in the visual setting.

No Build Alternative. If the Hoover Dam Bypass Project is not built, there will be no effect on
known/recorded historic properties. The known/recorded prehistoric archaeological sites
and historic archaeological features associated with the construction of the Old Boulder City
Water System and Hoover Dam are located well away from pedestrian or vehicle tourist
traffic. Hence, continued operation of the existing highway bridge (over the dam) and
existing highway approaches should have no effect on these resources. However, under No
Build, the traffic congestion on the historic two-lane crest roadway and approaches will
worsen, further degrade the historic setting, and increase the potential for traffic collisions
with dam appurtenances.
SCCV9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The presence of Hoover Dam and operation of the existing highway bridge and approaches
have diminished several traditional cultural values that the Indian Tribes ascribe to the
overall project vicinity. If the project is not built, there would be no further effects to the
TCP than those that presently exist. However, failure to build the project may result in
great harm to Native American cultural values if an accidental spUl (off the dam) of
hazardous materials pollutes the Colorado River.

3.5.3 Measures to Minimize Harm

For the NRHP eligible historic and cultural features affected by the project, formal
consultations with Nevada and Arizona SHPOs and the federal land-managing agencies
(NFS and Reclamation) were completed for the preferred alternative for determination of
specific measures to minimize harm to these cultural resource sites.

A PA that commits FHWA to implement specific activities and mitigation measures to
resolve the adverse effects on historic properties from the preferred alternative was
developed in consultation among the ACHP, FHWA, Nevada and Arizona SHPOs, NPS7
Reclamation, WAP A, NDOT, ADOT, and interested Native American tribal governments.
The PA stipulates, in part, that FHWA will establish a Design Advisory Panel (DAP) to
review bridge design concepts and corridorwide design elements, develop Corridor Design
Criteria for aesthetic consistency of major structural, roadway and earthwork elements,
mitigate adverse effects on historic resources according to the Secretary of Interior
Standards, and mitigate adverse effects on the TCP based on specific measures identified in
consultation with the Native American tribes who are invited signatories to the PA. The
DAP consists of members from FHWA, NDOT, ADOT, the Nevada and Arizona SHPOs,
the ACHP, the NHL Coordinator, NFS, Reclamation, WAP A, and consulting Native
American tribes, as well as an independent architectural historian and a registered
landscape architect. The PA includes a clause listing highway and power facilities
maintenance and operations exemptions for activities by Reclamation, WAP A, NPS, ADOT,
and NDOT within the TCP boundaries.

The PA incorporates a Treatment Plan for avoidance, minimization, and mitigation of
adverse effects to historic and cultural properties. The specific mitigation measures in the
Treatment Plan for historic resources include documenting the Hoover Dam National
Historic Landmark viewshed and related historic features in .accordance with the Historic
American Engineering Record (HAER) standards, determined in consultation with the
NPS/HAER. Mitigation measures currently identified for the TCP have resulted from the
ongoing government-to-government consultation meetings between FHWA, NPS,
Reclamation, and the Native American tribes. The mitigation measures recommended by
the tribes to date and incorporated in the PA include providing funding to the tribes for
continuing consultation through design and construction, providing access for the tribes to
the TCP, developing a statement of work for conducting future studies of cultural
landscapes in the surrounding area, and providing Native American cultural interpretive
exhibits in the vicinity of Hoover Dam.

3.5.3.1 Construction Mitigation
Promontory Point Alternative. In June 2000, FHWA applied the criteria of adverse effect and
determined in consultation with the Nevada and Arizona SHPOs that the Promontory Point
Alternative would have an adverse effect on the Hoover Dam NHL because the bypass
project would introduce visual elements that diminish the integrity of the property's
significant historic features and setting. Furthermore, FHWA and the NPS have determined

SCO/CHAP3.WPD/003672775 3-61
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

that construction of a bridge at the Promontory Point crossing would adversely affect
visitors' "first impression" historic views of the dam. These views occur as motorists
approach the dam on existing U.S. 93 from both Nevada and Arizona. The dominance of
the Promontory Point bridge would significantly detract from the historic views of the dam
and could not be mitigated. Measures to minimize harm would be required for segments of
the Old Government Railroad grade within Reclamation jurisdiction. Furthermore, because
the railroad is under conversion to a bicycle/pedestrian trail by NFS, it must be protected as
a recreation resource (see Section 3.8). Measures may be required for a portion of the
diversion tunnel and a small segment of the retaining wall because these features are
eligible as contributing elements to a potential historic district. Because the electric power
transmission switchyard is eligible as a contributing element to a potential historic district,
measures to minimize harm would likely be required. Mitigation would also be required
for the transmission towers in Nevada, the Old Arizona U.S. 93 highway segment, and the
TCP. Consultation with the Nevada and Arizona SHPOs would be required to determine
the nature and magnitude of the measures.

Mitigation for construction impacts to prehistoric archaeological sites NV:DD:14:23,
NV:DD:14:24, and NV:DD:14:25 would not be required because these sites were found
ineligible for the National Register. However, construction in these areas may require an
archaeological and Native American monitor, and in any cases of unanticipated discovery,
the finds would have to be secured and protected until appropriate actions could be
implemented.

Sugarloaf Mountain Alternative (Preferred Alternative). In June 2000, FHWA applied the
criteria of adverse effect and determined in consultation with the Nevada and Arizona
SHPOs that the Sugarloaf Mountain Alternative would have an adverse effect on the
Hoover Dam NHL because the bypass project would introduce visual elements that
diminish the integrity of the property's significant historic features and setting. However,
in contrast to the Promontory Point Alternative, FHWA and NFS determined the preferred
alternative bridge would not detract from the "first impression" historic views as visitors
approach the dam from the Arizona and Nevada approaches. The Design Advisory Panel
established in the PA will provide input on bridge design concepts, addressing structure
type, materials, and colors to minimize the visual impact.

The PA/Treatment Plan for the Sugarloaf Mountain Alternative includes other specific
measures to minimize harm to historic and cultural properties that will be directly impacted
during construction. For all adversely affected historic and cultural properties, the PA
identifies and requires an appropriate level of documentation for each site prior to
construction. The specific level of documentation for all properties, including HAER
recordation, will be determined in consultation with NPS/HAER authorities. HAER
recordation may include large format photography of affected features; measured drawings
where appropriate; reproduction of original design drawings, construction specifications,
and historic photographs; photography of the property setting; and a historical context.

In Arizona, the properties to be mitigated before they are impacted by construction consist
of historic transmission towers and lines to be removed and the Old Arizona U.S. 93
highway segment. In Nevada, the properties to be mitigated consist of the Old Government
Railroad grade, historic transmission lines and towers, and the stone gate structure. Since
NPS is converting the railroad grade to a bicycle/pedestrian trial, those critical segments
will be protected as a recreation resource through dose coordination between FHWA and
3-62 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

NFS (see Section 3.8). If the Arizona-Nevada Switchyard cannot be avoided by engineering
design, it too will be documented prior to any modification or demolition.

Mitigation for construction impacts to prehistoric archaeological sites NV:DD:14:21 and
NV:DD:14:22 will not be required because these sites were found ineligible for the National
Register; although, site NV:DD:14:?1 was found to be a contributing element of the TCP.
However, construction in these areas may require an archaeological and Native American
monitor, and in any cases of unanticipated discovery, the finds would have to be secured
and protected until appropriate actions could be implemented.

The PA/Treatment Plan for the preferred alternative incorporates measures to minimize
harm to the Gold Strike Canyon and Sugarloaf Mountain TCP. The Native American tribal
representatives, through a representative on the Design Advisory Panel, will have input to
the Corridor Design Criteria for the bypass roadway and bridge. Native American tribal
representatives may monitor construction of the roadway facility through the TCP area and
the related lithic scatter (NV:DD:14:21) located on the eastern flank of Sugarloaf Mountain.
Other mitigation measures that have been requested by the tribal representatives during the
government-to-government project consultation meetings will be elaborated and refined by
FHWA, the federal land managing agencies, and consulting tribes under the PA. The
specific measures that have been recommended by the tribes and included in the PA for
consideration by FHWA and the federal land managing agencies are to:
• Consummate a Memorandum of Understanding regarding the continued
government-to-government consultation between FHWA and the tribes
• Provide funds as available for ongoing tribal consultation
• Involve the tribes in the design aspects of the new bridge and roadway
• Continue the consultation with the tribes throughout the design and construction
process
• Protect the confidentiality of sensitive cultural information provided to the federal
agencies by tribal representatives
• Provide access for the tribes to traditional cultural places in the project area
• Develop a statement of work for conducting future cultural landscape studies for the
larger area encompassing the Gold Strike Canyon and Sugarloaf Mountain TCP
• Provide Native American cultural interpretive exhibits, developed in consultation with
tribal representatives
• Develop a separate treatment plan for any inadvertent discoveries of human remains
during any project-related activity
Gold Strike Canyon Alternative. In 1991, Reclamation, NFS, and the SHPOs concluded that
construction of the Gold Strike Alternative would have no adverse effect on the historic
visual setting of Hoover Dam, suggesting that measures to minimize harm would not be
required. Because the waste tailings on the Arizona site (NV:DD: 14:15) are eligible for
NRHP listing as contributing elements to a potential historic district, measures to minimize
harm could be required. The same situation would apply to the cantilevered walkway
(26-CK-4742) and tailings on the Nevada side (26-CK-4750). The tunnel (26-CK-4748), if
substantially altered to accommodate passage of large construction equipment, might also
be subject to measures because it is also eligible for NRHP listing as a contributing element
to a potential historic district. The TCP would be substantially impacted, and it is uncertain
if any mitigation would be acceptable to the tribes.

SCO/CHAP3.WPD/003672775 3-63
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

No prehistoric archaeological sites were detected in those portions of the Gold Strike
Canyon Alternative surveyed in March 1998 or examined by Reclamation's archaeological
staff in 1991 to 1992. Because no archeological sites were identified along this alternative,
no specific mitigation measures would be required; however, construction may require an
archaeological and Native American monitor, and in any cases of unanticipated discovery,
the finds would have to be secured and protected until appropriate actions could be
implemented.

3.5.3.2 Operational Mitigation

Promontory Point Alternative. As noted above, construction of the Promontory Point
Alternative would result in adverse effects on the historic visual setting of Hoover Dam.
These visual impacts are considered by FHWA and NFS to be unmitigable. Therefore, no
available measures exist to minimize harm during project operation.

The portion of the Old Government Railroad grade directly impacted by the Promontory
Point Alternative would be mitigated according to the measures defined in the PA for the
preferred alternative. Given the substantial impact to the railroad grade by the Promontory
Point alignment, conversion of the grade as a bicycle/pedestrian trail by NPS may not be
practicable under this alternative (see Section 3.8).

Measures to minimize harm may be required during construction for the portion of the
diversion tunnel and small segment of the retaining wall because these features are eligible
as contributing elements to a potential historic district. Once constructed, it is unlikely that
harm minimization measures would be required for these two features during project
operation.

Operation of the Promontory Point Alternative would affect the historic setting of the old
building foundations (near the bridge abutment) and the remaining transmission towers in
Nevada. Mitigation measures likely would be required. Because the electric power
transmission switchyard is also eligible as a contributing element to a potential historic
district, measures to minimize harm would likely be required during construction; but once
constructed, such measures are not likely to be required during project operation.
Consultation with the Nevada SHPO would be required to determine the nature and
magnitude of the measures.

The historic setting of the World War II Bunker on the Arizona side would be affected by
the operation of the bypass passing below it on this alignment. Consultation with the
Arizona SHPO would be required to determine the nature of any mitigation measures
needed to resolve this impact.

Site AZ:NV:DD:14:23, found ineligible for the NRHP, would probably be destroyed by
construction; therefore, operational impacts would be irrelevant. Sites AZ:NV:DD: 14:24
and -25 are also not eligible for NRHP listing, and mitigation would not be required.

Sugarloaf Mountain Alternative (Preferred Alternative). As noted above, construction of the
Sugarloaf Mountain Alternative would produce adverse effects to the historic visual setting
of Hoover Dam. Operation of the Sugarloaf Mountain Alternative will change the
long-term visual setting of the historic landmark, as well as the Kingman Switchyard and
the Sugarloaf Mountain Survey Station in Nevada, the U.S. 93 Switchback in Arizona, and
the remaining historic transmission towers and lines in both states.
3-64 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Input by the Design Advisory Panel on bridge design concepts, structure type and
materials, and in developing corridorwide design criteria will mitigate the total project
effects on the NHL and other proximate historic properties, as stipulated in the PA. The
panel will consist of representatives from FHWA, ACHP, the National Historic Landmark
Coordinator, NPS, Reclamation, WAP A, the signatory Native American tribes/ the Nevada
and Arizona SHPOs, NDOT, ADOT, an independent architectural historian, and an
independent registered landscape architect. Design enhancements from this panel will
minimize both the short-term construction impact as well as the long-term operation impact
of the new highway bypass on the historic landscape.

Construction impacts may require mitigation of AZ:NV:DD:14:21 as a contributing element
of the TCP. Site AZ:NV:DD:14:22 is not eligible, and mitigation would not be required.
Operational impacts on the TCP will be minimized through measures applied from the PA.

Gold Strike Canyon Alternative. As noted above, construction of the Gold Strike Canyon
Alternative would have no adverse effect to the historic visual setting of Hoover Dam,
suggesting that measures to minimize harm would not be required, either during
construction or operation. Because the waste tailings on the Arizona site are eligible for
NRHP listing as a contributing element to a potential historic district, measures to minimize
harm during construction could be required. Once implemented, however, it is unlikely
that further measures to minimize harm would be required during operation. The same
situation would apply to the cantilevered walkway and tailings on the Nevada side. The
tunnel, if substantially altered to accommodate passage of large construction equipment,
might also be subject to measures because it too is eligible for NRHP listing as a
contributing element to a potential historic district. Once implemented, however, it is
unlikely that further measures to minimize harm to the tunnel would be required.

No archaeological sites were identified in this alternative; therefore, no impacts are
expected and no mitigation required.

Ail Alternatives. Operation of any of the build alternatives would diminish the integrity of
the visual and audible setting of the Gold Strike Canyon and Sugarloaf Mountain TCP on a
long-term basis. The mitigation measures and treatment approach incorporated in the PA
and described in Section 3.5.3.1 for the preferred alternative will be further refined and
possibly expanded during continued consultations between FHWA, the land managing
agencies, and the tribal representatives, with the goal of minimizing the intrusion of the
highway bypass on future Native American uses of the TCP.

No Build Alternative. No mitigation measures would be required to reduce harm to
prehistoric and historic archaeological sites and features if the project is not built.

Indian tribes that participated in this investigation suggested several measures that would
reduce adverse effects to their TCP and its associated cultural values if the project is built.
Some of these measures could be implemented in a no build scenario to mitigate the
existing harmful effects of the existing conditions on these cultural values (e.g., a monument
to Indian peoples, educate Indians and non-Indians that Hoover Dam is where Indian
ancestors lived, close the hot springs and open them only to the Indians, set aside an area(s)
for Indian use, and include Indian tribes in comanagement of lands in the project area).
SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.6 Land Use

3.6.1 Affected Environment

This section discusses existing land uses in the vicinity of the three build alternatives. Three
types of federal land are in the proposed project area: LMNRA, administered by the NFS;
Hoover Dam Reservation (HDR), administered by Reclamation; and the Hoover Dam
National Historic Landmark (HDNHL), also administered by Reclamation (see Figure 2-3).
Current land uses are described below. A Section 4(f) evaluation pertaining to federally
protected parklands and historic sites was prepared and is included as Chapter 6. The
proposed project area is entirely on federal lands located within Clark County and Mohave
County. For comparative purposes, brief descriptions of applicable land use policies are
given below.

The Promontory Point and Sugarloaf Mountain Alternatives would traverse LMNRA, HDR,
and HDNHL lands; the Gold Strike Canyon Alternative would traverse only LMNRA and
HDR lands. The portions of the three alternatives on the Nevada side of the Colorado River
are in Clark County, and the portions on the Arizona side of the Colorado River are in
Mohave County.

3.6.1.1 Existing Land Uses in the Project Area and Vicinity
To characterize existing land uses along the three build alternative alignments and in the
vicinity, on-the-ground and drive-by area surveys were performed March 9 and 10,1998.
Outside the proposed project area, immediately west of the western terminus of the three
build alternatives is the Hacienda Hotel (formerly called the Gold Strike Inn at the time of
the survey). Outside the proposed project area, immediately east of the eastern terminus of
the three build alternatives is undeveloped open space. Immediately north and south are
lands dedicated to open space and recreational uses. To the north is Lake Mead; to the
south is the Colorado River. Hoover Dam separates the two water features. Most of the
proposed project area is undeveloped open space, portions of which are used for
recreational purposes.

Existing land uses along the Promontory Point Alternative and in its vicinity include
undeveloped recreational land (36 acres minimum, Mohave County General Plan) and
electric transmission and distribution facilities and other facilities associated with Hoover
Dam.

Existing land uses along the Sugarloaf Mountain Alternative and in its vicinity include
undeveloped recreational land, a water tank/sewage evaporation ponds, and electric
transmission facilities associated with Hoover Dam. About 400 feet downstream of this
alternative is a rafting concessionaire's put-in on the Colorado River. Access to this put-in
is provided by Reclamation's restricted access Lower Portal Road. Reclamation operates a
warehouse associated with the dam operations approximately midway between the
western terminus and Hoover Dam.

Existing land uses along the Gold Strike Canyon Alternative and in its vicinity include
undeveloped recreational land and an undesignated trail used to hike through Gold Strike
Canyon down to the river. Near the mouth of the canyon are the drainages of geothermal
seeps and hot springs, some of which have human-made blockages to form ponds of warm
water. These ponds are used for recreational purposes.

3-66 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Farmlands. As previously noted, most land within the vicinity of the proposed project is
undeveloped, with a large portion dedicated to recreational uses. Agricultural land uses
typically are not excluded from these areas.

As a result of a substantial decrease in the amount of open farmland, Congress passed the
Farmland Protection Policy Act (PL 97-98; 7 U.S.C. 4201 et seq.). The purpose of the Act is
to minimize the unnecessary and irreversible conversion of farmland to nonagricultural
uses by federal programs/actions. The Act further requires that federal programs/actions
be administered in a manner that will be compatible with state and local government and
private programs and policies to protect farmland. The Act specifies three categories of
farmlands:
• Prime farmland—land that has the best combination of physical and chemical
characteristics for producing food, feed, fiber, forage, oilseed, and other agricultural
crops with minimum inputs of fuel, fertilizer, pesticides, and labor, and without
intolerable soil erosion (7 U.S.C. 4201[c][l][AJ).

• Unique farmland—land other than prime farmland that is used for the production of
specific high-value food and fiber crops such as citrus, tree nuts, olives, cranberries,
fruits, and vegetables (7 U.S.C. 4201[c][l][B]).

• Additional farmland of statewide or local importance—land identified by state or local
agencies for agricultural use, but not of national significance (7 U.S.C. 4201[c][l][C]).

No present agricultural land uses that fall within these farmland categories have been
identified within the project vicinity.

3.6.1.2 Land Use Planning
The Clark County General Plan, Mohave County General Plan, the LMNRA General
Management Plan (GMP), Reclamation's Hoover Dam Reservation, and the National
Historic Landmark are the development guides in the proposed project area. Although the
land use plans for Clark and Mohave Counties have no legal authority over management of
federal lands, federal agencies strive to achieve conformance with adjoining land use plans.

Clark County General Plan. The proposed project area within Nevada is located within Clark
County. The Clark County General Plan lists several general planning goals applicable to
the proposed project. These goals are provided below.

• Goal 1: To promote public health, safety, and welfare
• Goal 2: To promote efficient use of public services
• Goal 3: To promote development compatible with the natural environment

Mohave County General Plan. The proposed project area within Arizona is located within
Mohave County. The Mohave County General Plan lists several major planning concepts
that define its vision for year 2010. Among these are three concepts applicable to the
project: promote beneficial economic growth, development, and renewal; protect the
environment; and preserve and enhance historic, cultural, open space, and recreational
lands and structures.

Transportation is addressed as part of the General Plan's Public Infrastructure Element.
The County recognizes the relationship between land uses and transportation facilities. In
addition, the County acknowledges the importance of compatibility of the County's
roadway system with city, state, and federal roads. General Plan transportation policies

SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

apply to streets within the County's jurisdiction, namely arterial roads and collectors within
the County's street system. No specific General Plan transportation policies apply to the
proposed project area; however, the following three goals generally apply to the proposed
project area:

• Goal 51: To plan, construct, and maintain an efficient transportation system that is
adequate to meet the mobility needs of County residents and businesses

• Goal 52: To promote compatibility between roadway improvements, land use patterns,
and natural features

• Goal 53: To minimize the impacts of automobile travel on the County's air quality,
natural environment and developed communities (Freilich, Leitner & Carlisle, 1995)

Lake Mead National Recreation Area General Management Plan. The LMNRA GMP, prepared
by the NFS, provides a management strategy for the two reservoirs (Lake Mead and Lake
Mohave) and surrounding lands within the National Recreation Area (NRA). The NRA
contains 1,482,476 acres of federal land and 28,212 acres of nonfederal land (see Figure 6-1).

The NFS management strategy focuses on accommodating increasing visitor use at the
NRA while protecting the area's most outstanding natural and cultural values. The NFS
seeks to provide a quality visitor experience in a manner that will ensure visitor safety and
will protect the area's significant resources. Due to increasing demands on the park's
waters, shoreline resources, and facilities, a Lake Management Plan is in preparation. This
plan will supplement the GMP in the areas of recreational carrying capacity and shoreline
recreation facilities.

Hoover Dam Reservation. The Hoover Dam Reservation (Reservation) delineates lands
managed by Reclamation for security purposes and for operating and maintaining Hoover
Dam, its buildings and structures, electric transmission lines, towers, switchyards, and spoil
disposal sites. No specific management plan has been prepared for guiding development
within the Reservation; however, public access to certain areas within the Reservation is
restricted, and portions of the area are fenced. As such, Reservation lands do not fall under
federal parkland protective provisions (see Chapter 6). Controlled access to the Colorado
River about 1 mile west of Hoover Dam is provided by a locked gate at the Lower Portal
Road and U.S. 93 intersection. Access is allowed to a rafting concessionaire, a tour group
operator, and individuals having permits issued by Reclamation.

Hoover Dam National Historic Landmark. Hoover Dam is a designated National Historic
Landmark and is listed in the National Register of Historic Places. It is under the
jurisdiction of Reclamation. National Historic Landmarks identify, designate, recognize,
and protect buildings, structures, sites, and objects of national significance. The NPS, in
cooperation with other government agencies, professionals, and independent organizations,
administers the landmark program. Once a site is designated a National Historic
Landmark, the owner maintains all rights and privileges of ownership. However, the
designation requires that federal transportation projects affecting a landmark take steps to
minimize harm to the affected property, under Section 4(f) of the Department of
Transportation Act. The dam also falls under the protective provisions of Section 106 of the
National Historic Preservation Act.
3-68 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.6.2 Environmental Consequences
3.6.2.1 Construction Impacts
Consequences associated with development of the project alternatives, including the
preferred alternative, are based on the compatibility of the alternatives with both existing
land uses and applicable planning documents governing the use of project lands. Changes
in land use and patterns resulting from the three build alternatives evaluated are generally
consistent with federal and local land use plans. Impacts from the three build alternatives
are separated into those associated with construction, and those resulting from operation of
the alternatives.
Potential effects on land use are associated with project construction rather than operation
because once the right-of-way easement has been granted and construction begins, no
further changes to land use patterns are expected. Existing land uses surrounding the
proposed project area would not be precluded during the construction period. Access to
most existing land uses would be maintained; the exception is the trail in Gold Strike
Canyon, which would be closed to public access during construction of the Gold Strike
Canyon Alternative.
The primary land use change associated with the build alternatives is the development of
currently undeveloped recreational land for a four-lane highway in the proposed project
area. Table 3-18 shows the total acreage that would be developed in each jurisdiction.

Table 3-18
Acreage to be Developed for Each Build Alternative'
Jurisdiction
Lake Mead National Recreation Area
National Historic Landmark Boundary
Hoover Dam Reservation
Total Acreage
Promontory Point
94.5
40.6
73.9
209.0
Sugarloaf Mountain
95.9
25.7
70.7
192.3
Gold Strike Canyon
97.1
0.0
81.2
178.3
•Includes areas of all potential project components.

3.6.2.2 Operational Impacts
Existing land uses surrounding the proposed project area would not be affected following
project completion. The change from recreational land to highway would constitute a small
change when compared to the expansive amount of open space area in the surrounding
region. Access to existing land uses would be maintained during project operation. No
operational impacts on air quality were identified with the build alternatives; however, the
Gold Strike Canyon Alternative would have an unmitigable noise impact on recreational
land uses.

3.6.2.3 No Build Alternative
Because the No Build Alternative would result in no construction, no land use changes
would occur. However, there would be negative effects on visitor usage as congestion
increases on the dam.
SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

3.6.3 Measures to Minimize Harm

Noise, visual, and access impacts on recreational land use with construction and operation
of the Gold Strike Canyon Alternative could not be mitigated (see Section 3.8.3.2). No other
adverse impacts on land use from construction or operation were identified; therefore, no
mitigation is warranted.

3.7 Visual Resources

3.7.1 Affected Environment

3.7.1.1 Visual Environment

Landscape Description. The proposed project area is within the LMNRA, which retains an
undisturbed character throughout much of its area, but also includes some developed
facilities. The desert in the proposed project area is at elevations ranging from about
650 feet to about 2,000 feet Soils in the proposed project area are pink, red, and
brownish-gray. Landforms are mountains, valleys, and beaches, and include the deeply
incised Black Canyon, Gold Strike Canyon, and Sugarloaf Mountain. Landcover in the
proposed project area includes Lake Mead, the Colorado River, low-lying and sparse desert
vegetation, rock formations, and human-made development such as Hoover Dam facilities,
electric transmission towers and lines, access roads, and U.S. 93.

Visual Character. Primary forms in the proposed project area are Lake Mead, Hoover Dam,
Colorado River, and Black Canyon. Hoover Dam, viewed either from U.S. 93 or from the
air, is a large mass. Views from the dam, lake, river, or canyon also show the area's variety
of forms. Aerial views and views from the river and dam all exhibit strong lines. For
example, Hoover Dam provides both horizontal and vertical lines in the landscape. Electric
transmission towers and lines provide angled, vertical, and horizontal lines. U.S. 93
introduces a horizontal line across the landscape. The walls of Black Canyon exhibit
vertical lines, and viewed from the air, the river exhibits a meandering line.

Color variety in the proposed project area is evidenced by the Canyon's pinkish-brown rock
formations and soils; lightness is introduced by the concrete of the dam structure; and
brightness is provided by the sun's reflection off the dam, lake, and river. Additional color
is added by the blues and greens of the lake and river. Area texture includes rock
formations, topography, water surfaces, and low-lying vegetation.

Outside of Lake Mead, Hoover Dam is the most dominant human-made feature within the
proposed project area. Its position in the canyon relative to overlooks, viewpoints, and the
visitor center clearly make it the visual focus. Its size makes it an impressive structure, and
its placement within the deep canyon makes it compatible with the area. Visual diversity is
provided by the mixture of natural and human-made environment such as the variety of
forms; straight and curved lines; lightness, darkness, and color variety; and textural variety
offered by ground surface relief and vegetation. The area's landscape forms, lines, color
combinations, and textures all contribute to visual continuity.

Visual Quality. Three criteria were used to evaluate the proposed project area's visual
quality: vividness, intactness, and unity. Determining vividness of the proposed project
area includes assessing the area's landforms, landcover, and human-made development.
The proposed project area's vividness rating is high. The area's landforms (steep canyon
walls and mountains) contribute to the memorable view. Water bodies (both lake and

3-70 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

river) provide a vivid landscape because of their color, reflection of sunlight, motion, and
shoreline. Human-made development in the area contributes to the view's vividness by its
contrast with the natural landscape (the dam and its facilities, angled design of electric
transmission line towers, parking lots, and roads).

Intactness of the proposed project area is demonstrated by the integrity of the features.
Human-made features add to the area's complexity and visual variety: The area appears
very ordered; a view of the dam from downstream exhibits symmetry and strong lines.

Landscape unity is achieved by the mixture of natural elements and human-made
alterations. Compatibility exists between the natural landscape (canyon, lake, and river)
and the human-made facilities (dam, electric transmission lines, visitor center, parking lots,
concessions, and road).

The NFS considers many natural features within the LMNRA to be outstanding.
Uniqueness, critical habitat protection, and aesthetic and recreational value are criteria used
by the NFS to consider natural features outstanding. Features include warm springs,
unique geologic formations and plant communities, scenic vistas, desert bighorn lambing
grounds, and coves popular for their sandy beaches or scenic beauty.

Black Canyon is the only site near the proposed project area afforded special protection by
the NFS because of its geologic and scenic values, numerous hot and warm springs, and
winter habitat for bald eagles. The NFS-protected area begins about 1 mile south of the
Gold Strike Canyon Alternative and extends south for about 9 miles. In addition to
protecting the integrity of the natural feature, the NFS indicates that the views provided by
this feature must also be considered. Therefore, the NFS indicates that if development
around Black Canyon is made visible from U.S. 93 on the Arizona side of Hoover Dam, the
canyon's scenic integrity would be compromised. In addition, the NFS recognizes that the
view corridor from the Colorado River through Black Canyon is an outstanding view that
should be protected (NFS, 1986).

National Scenic Byways possess outstanding qualities that exemplify a region's
characteristics. No National Scenic Byways are in Nevada or Arizona near the proposed
project area. U.S. 93 is a Nevada Scenic Byway; however, it is not designated as such in or
near the proposed project area. No Arizona Scenic Byways are in or near the proposed
project area.

No rivers in Nevada or Arizona near the proposed project area are designated pursuant to
the Wild and Scenic Rivers Act.

3.7.1.2 Viewer Characteristics
Viewer Groups, Exposure, and Sensitivity. For all three build alternatives, viewer groups can
be classified as one of two types:

• Recreationists visiting the Hoover Dam area (including Hoover Dam itself, Lake Mead,
Colorado River, and Black Canyon)

• Drivers and passengers traveling in vehicles through the Hoover Dam area

Recreationists are considered a sensitive viewer group because their viewing of the dam,
the lake, the river, and the canyon is expected to last up to several hours. Recreationists
generally value, and are more aware of, the aesthetic quality of their surroundings than
commuters or people at work, because their focus is usually on their surroundings while

SCO/CHAP3.WPD/003672775 3-71
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

they are relaxing; or the recreational activity they are engaging in, which is usually
enhanced by their surroundings. Because Hoover Dam, a National Historic Landmark
visited by more than 1 million tourists annually, is so well known both nationally and
internationally, and provides spectacular photograph opportunities, recreationists visiting
the Hoover Dam area are considered particularly sensitive to the surrounding views.

Drivers and passengers traveling over Hoover Dam (through traffic) are considered a less
sensitive viewer group than reereationists because of their relatively short view time while
traveling across the dam, the obstructed views offered from within vehicles, and because
their focus is to negotiate a vehicle in traffic congestion and reach a final destination. Scenic
driving for pleasure is a valid recreational activity, and the sensitivity of such viewers
should not be ignored. However, because of the short view time, the driver distraction
occurring from traveling in heavy traffic, and the obstructed views within vehicles while
crossing the dam, these travelers are considered less sensitive viewers than recreationists.

Recreationists' Existing Views. Recreational boaters on Lake Mead experience unobstructed
views of Black Canyon and Hoover Dam from up to 1.2 miles upstream. Recreationists on
Lake Mead or its shores do not have views of the downstream side of the dam, Black
Canyon downstream of the dam, or the Colorado River.

Recreationists visiting Lakeview Point Overlook in Nevada have a view of Lake Mead.
Viewer groups at the Arizona Lookout and parking areas have a view of the dam and lake.
Recreationists on the dam crest looking upstream have an unobstructed view of Lake Mead
and Black Canyon for 1.2 miles. Looking downstream from the dam crest, recreationists
have an unobstructed view of the Colorado River and Black Canyon for 0.5 mile.

Recreationists on the Colorado River at the rafting and canoeing put-ins about 0.5 mile
downstream of Hoover Dam have an unobstructed view of the dam and Black Canyon
when looking upstream. From the put-ins looking downstream, recreationists have
unobstructed views of the Colorado River and Black Canyon for about 0.6 mile.

Recreationists hiking the Gold Strike Canyon trail have limited views. Because Gold Strike
Canyon is narrow, winding, and steeply sloped, views of Hoover Dam from the trail are
precluded. From the trail, views of the Colorado River and Black Canyon are completely
obstructed until the last 0.1 mile of the trail.

Recreationists at the hot springs in Gold Strike Canyon have views of the Colorado River
and Black Canyon from the pool closest to the river; views of the river and the canyon from
the other pools are obstructed. Views of Hoover Dam (upstream) from the hot springs are
completely obstructed.

Drivers' and Passengers' Existing Views. Drivers and passengers traveling over existing
U.S. 93 and Hoover Dam have limited views. At a speed of 10 mph, a vehicle crosses the
dam in 1.5 minutes, which is considered a- short view'time. In addition, from passenger
vehicles traveling east, Lake Mead and the Colorado River cannot be seen at all, and views
of Black Canyon are limited. Views from passenger vehicles traveling west are obstructed
in a similar manner. The viewshed from within higher vehicles, such as commercial trucks,
is greater than from passenger vehicles, but is still of short duration and is partially
obstructed by the vehicle itself.
3-72 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.7.2 Environmental Consequences

3.7.2.1 Construction Impacts
Impacts on visual resources during construction that are common to all three build
alternatives include the following:

• Dust would be emitted from earthmoving activities, construction vehicles and
equipment, construction worker vehicles, materials delivery vehicles, and from areas
within the construction zone that have been disturbed or where excavated material is
stockpiled. Fugitive dust, if emitted in sufficient quantities, and if adverse weather
conditions persist, could impair or degrade existing views (either from the ground or
from the air).

• Depending on their values, interests, and preconceived expectations, for some
recreationists viewing the area (either from the ground or from the air) the presence of
construction equipment and its associated activities would detract from the views
currently experienced. For other recreationists, the presence of equipment and
highway/bridge construction would be interesting and would add visual variety to the
landscape, creating additional photographic opportunities.

• Hoover Dam is currently lit at night and provides interesting nighttime views. For
some recreationists, the additional light mat would be emitted during nighttime
construction (if it occurs) would detract from the nighttime views experienced during
the dam visit. Depending on their values and expectations, for other recreationists, the
additional light and associated construction activities would add visual interest to the
setting. This issue would be of less concern to recreationists if the Gold Strike Canyon
Alternative were constructed, because that alternative is not visible from Hoover Dam.
However, the canyon downstream might appear brighter during nighttime construction
if that alternative were selected.

Promontory Point Alternative. Construction of the Promontory Point Alternative would last
approximately 5 years. During construction of this alternative, the view of Lake Mead from
Hoover Dam (regardless of bridge design) would be altered from its existing, primarily
undisturbed, state to one exhibiting a highly disturbed character. Construction vehicles,
equipment, and personnel would alter the slopes on both sides of the lake. The waste
disposal area would not be visible from the dam, river, or lake, but would be seen from
U.S. 93 in Arizona.

Changes to the visual environment in the area of this alternative would be noticeable to
visitors to the dam, the lake (when near the dam), and from the air. As discussed
previously, changes to the landscape are expected to be offensive to some viewers and
interesting to others. The impact on visual resources from construction activities would not
be permanent, but because of the length of the construction period, they are not short-term.
Other existing views, such as from the rafting put-ins on the Colorado River and the hiking
trail and hot springs, would not be affected.

Sugarloaf Mountain Alternative (Preferred Alternative). Construction of the preferred
Sugarloaf Mountain Alternative is expected to last approximately 5 years. During
construction of this alternative, the view of Black Canyon from Hoover Dam and Lake
Mead would be affected. Although the view area is already largely disturbed, construction
vehicles, equipment, and personnel would alter the slopes on both sides of the canyon.

SCO/CHAP3.WPD/003672775 3-73
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Changes to the visual environment in the area of this alternative would also be noticeable
from the dam, the river (when near the dam), and from the air. Construction vehicles,
equipment, and personnel would alter the canyon slopes on both sides of the river, and the
emerging bridge structure would become a dominant visual element. As discussed
previously, changes to the landscape are expected to be offensive to some viewers and
interesting to others. The impact on visual resources from construction activities would not
be considered permanent, but because of the length of the construction period, they are not
considered short-term. Other existing views, such as from the hiking trail and hot springs,
would not be affected.

Gold Strike Canyon Alternative. Construction of the Gold Strike Canyon Alternative would
last approximately 5 to 6 years. During construction of this alternative, views from the lake
or dam toward the Gold Strike Canyon Alternative (regardless of bridge design) would not
be affected because that alternative cannot be seen from the lake or dam.

Changes to the visual environment in the area of this alternative would be noticeable from
the river and the air. Construction vehicles, equipment, and personnel would alter the
canyon slopes on both sides of the river. One waste disposal area would be visible from the
trail, and another disposal area would be visible from U.S. 93 in Arizona. No waste
disposal areas would be visible from the dam, lake, or river. In addition, areas for cut and
fill and materials laydown would be visible from the put-in area on the Colorado River. As
discussed previously, changes to the landscape are expected to be offensive to some
viewers, and interesting to others. The impact on visual resources from construction
activities would not be considered permanent, but because of the length of the construction
period/they are not considered short-term.

Much of the Gold Strike Canyon Alternative would either parallel or cross the canyon
hiking trail. Use of the trail would be precluded during construction of this alternative;
therefore, existing views from the hiking trail would be eliminated. Because the trail
would be closed to the public, access to the hot springs would only be available from the
river. The view from the hot springs looking directly north toward the Gold Strike Canyon
Alternative would be obstructed by topography and, therefore, would not be affected. The
view from the hot springs looking to the northwest would be affected by construction
equipment and activities.

No Build Alternative. Because the No Build Alternative would result in no construction, no
construction-related impacts on existing visual resources are expected at Hoover Dam, Lake
Mead, the Colorado River, Black Canyon, or the Gold Strike Canyon hiking trail and hot
springs. In addition, no construction-related impacts on aerial views would occur.

3.7.2.2 Operational Impacts
Visible structural features of the three build alternatives have been assessed and compared
with the area's pattern elements and character, and its vividness, intactness, and unity to
determine the compatibility of the proposed features with the existing landscape.

Figure 3-4 shows the four viewpoints selected for visual simulations. To show what is
currently visible from four viewpoints in the proposed project area, photographs were
taken at each location. These photographs serve as existing condition views and provide
the basis for comparing various bridge designs and alternatives being considered.
Alternative bridge designs have been superimposed onto the photographs in visual
simulations. The following viewpoints were selected:

3-74 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• From aboard the Desert Princess on Lake Mead looking toward Hoover Dam
(Figures 3-5,3-6, and 3-10)

• From the Arizona Overlook toward Lake Mead (Figures 3-7 and 3-8)

• From atop Hoover Dam on the Arizona side looking downstream (Figures 3-9 and 3-10)

• From the rafting put-in on the Colorado River about 0.5 mile downstream of Hoover
Dam looking south (Figures 3-11 and 3-12)

Figure 3-4 shows the locations of each of the four viewpoints and the alignments of the
three build alternatives. As shown in Figure 3-4, the direction of each view is toward one of
the three alternatives. The viewpoints chosen are popular photograph opportunity
locations. Viewpoints 1 through 3 were selected because they represent views that
recreationists would experience while visiting the Hoover Dam area. Many locations exist
at the dam, lake, and scenic lookouts where photographs could be taken, and many views
from each location could be generated. The location and direction of each photograph
taken are considered representative of the views provided while at the Hoover Dam area.

Viewpoint 4 was chosen to show the view seen by the 18,500 recreationists who put-in
annually to raft or canoe the Colorado River. Because the Gold Strike Canyon Alternative is
not visible from Hoover Dam but is visible from the put-in location, the river put-in
provides the best view of that alternative by recreationists. Although a view looking
upstream toward Hoover Dam could also have been provided from Viewpoint 4 (which
would have shown the Sugarloaf Mountain Alternative), it was determined that the
Sugarloaf Mountain Alternative could be adequately assessed from Viewpoint 3, a location
visited by more tourists than Viewpoint 4.

Impacts Common to All Build Alternatives. Adding a bridge and its associated facilities to the
landscape in the Hoover Dam area would alter the landscape. Regardless of the alternative
implemented, these facilities would be visible from at least one viewpoint. For some
viewers, these features would add visual variety and interest to the landscape. For other
viewers, the addition of such features would detract and possibly even degrade the
landscape. If the proposed project is implemented, regardless of the alternative selected, a
new view of the surrounding landscape from the bridge and its roadway approaches would
be created. The view on the bridge would be limited to features seen from moving vehicles
traveling about 60 mph; bicyclists, pedestrians, and stopped vehicles would not be allowed
on the new bridge.

However, as discussed in Volume n, in anticipation of great public desire for views of
Hoover Dam from the new bridge on the Sugarloaf Mountain alignment, FHWA will study
the technical feasibility of a separate viewing facility associated with the bridge. Further
details of such a facility cannot be determined until design of the bridge and approaches is
advanced beyond the current level. Details of how people would be conveyed to the
viewing facility and evaluation of environmental impacts would be addressed in a separate
NEPA document, written for the specific purpose and need of providing views of Hoover
Dam from or in the vicinity of the new bridge, if the construction scope of the viewing
facility exceeds the anticipated impacts addressed in this EIS.

Promontory Point Alternative. Views of the Promontory Point Alternative would be
unobstructed from locations on Lake Mead up to 1.2 miles upstream of the dam. The new
bridge would be visible from Hoover Dam and by aerial sightseers, thus changing the
landscape setting of Lake Mead from the dam and the air. For some viewers, this change
SCO/CHAP3.WPD/003672775 3-75
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

would detract from the lake's view. This viewer group expects the views to be unchanged
from existing conditions, or expects the changes to be unnoticeable or unobtrusive. For
others, the bridge design would add variety to the lake view. This viewer group would
notice the visual change, but would not be offended by the change to the view.

A bridge at the Promontory Point crossing would adversely affect visitors' "first impression"
historic views of the dam. These views occur as motorists approach the dam on existing
U.S. 93 from both Nevada and Arizona. The dominance of the Promontory Point bridge
would significantly detract from the historic views of the dam and could not be mitigated.
In contrast, the Sugarloaf Mountain bridge would not detract from the historic views as
visitors approach the dam from the Arizona and Nevada approaches. (See Figures 3-7 and
3-8 for views from the Arizona Overlook.)

Steel Truss Rib Through Arch Bridge from Viewpoint 1. Figures 3-5 and 3-6 show Hoover
Dam from aboard the Desert Princess on Lake Mead (Viewpoint 1). The top photograph in
Figure 3-5 shows the existing view from the boat toward Hoover Dam. The top photograph
in Figure 3-6 simulates what a steel truss rib through arch bridge crossing Lake Mead
would look like from aboard the Desert Princess. This bridge design would add a large
form, contrasting lines, unobtrusive color, and texture changes (from the appearance of
lattice steelwork on the arch) to the view.

From this viewpoint, the Hoover Dam facilities and electric transmission line towers are
subordinate features and do not detract from the existing view. The position, size, and
shape of the steel truss rib through arch bridge make it a feature that would dominate the
view from the boat. This bridge design would add to visual diversity by intermixing
horizontal, vertical, and curved lines to a predominantly undisturbed view of the
landscape. Although adding diversity, the bridge would not add visual interest to the
landscape. In addition, it would interrupt the visual continuity of the mountains in the
background because of the presence of the arch and vertical bridge lines near the center of
the photograph.

The visual quality shown in Figure 3-5 would be affected by this bridge design. Vividness
would be compromised by the introduction of the bridge structure. In addition, the
landscape intactness and unity would be affected by the size and prominence of the form,
contrasting lines, and textural differences between the proposed bridge and the existing
landscape.

Hoover Dam and Lake Mead would be visible to motorists traveling over the new bridge;
however, the view would be partially obstructed by the safety barrier that would be
installed on both sides of the bridge. Because stopped vehicles, bicyclists, and pedestrians
would be precluded from the new bridge, and vehicle speeds across the bridge would be
60 mph, the new bridge would not provide the benefits of extended viewing opportunities
of Lake Mead and Hoover Dam.

Concrete Cable-Stayed Bridge from Viewpoint 1. Also shown in Figure 3-6 from aboard the
Desert Princess on Lake Mead (Viewpoint 1) is a simulation (lower photograph) of how a
concrete cable-stayed bridge crossing Lake Mead would look from this viewpoint. This
bridge design would add a large form that exhibits little texture; contrasting diagonal,
vertical, and horizontal lines; and a color contrast from the concrete towers.
3-76 SCO/9820800.WPD/003672775
-------
Viewpoint

Promontory Point Alternative
Sugarloaf Mountain Alternative
Gold Strike Canyon Alternative
U.S. 93
FIGURE 3-4
VIEWPOINTS FOR
VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
0 650 1300 FEET
!
SCALE IS APPROXIMATE

SCO142863.15.06 \Mwp>Ms2tl 11OO
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAI. CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-78 SCO/9820800.WPD/003672775
-------
••> ' *»
XT-- » i"'.-',, ,i "•«,'•-
• ~ >.'• •M.'f'f
Existing conditions view from the Desert Princess on Lake Mead (Viewpoint 1)
View of suspension bridge from the Desert Princess on Lake Mead
(Viewpoint 1)
142863.12.PM 2439 06a
FIGURE 3-5
PROMONTORY POINT ALTERNATIVE
VISUAL SIMULATIONS
HOOVER DAM BYRASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-80 SCO/9820800.WPD/003672775
-------
View of steel truss rb through arch bridge from the Desert Princess on Lake Mead
(Viewpoint 1)
View of concrete cable-stayed bridge from the Desert Princess on Lake Mead
(Viewpoint 1)
142883.12.PM 2«9_06C tl 996
FIGURE 3-6
PROMONTORY POINT ALTERNATIVE
VISUAL SIMULATIONS
HOOVER DAM BYFttSS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
3-R1
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-82 SCO/9820800.WPD/003672775
-------
Existing conditions view from the Arizona Overlook (Viewpoint 2)
View of cable-stayed bridge from the Arizona Overlook (Viewpoint 2)
1428S3.12.PM 2439_07a
FIGURE 3-7

PROMONTORY POINT ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-84 SCO/9820800.WPD/003672775
-------
View of steel truss rib through arch bridge from the Arizona Overlook (Viewpoint 2)
View of suspension bridge from the Arizona Overlook (Viewpoint 2)
142883 12-PM 243g_07b t> »98
FIGURE 3-8
PROMONTORY POINT ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-86 SCO/9820800.WPD/003672775
-------
.«<*&
Existing conditions view looking south from Hoover Dam (Viewpoint 3)
1428B3.12PM 2439.048 th 9198
View looking south of concrete cable-stayed bridge from Hoover Dam (Viewpoint 3)
FIGURE 3-9

SUGARLOAF MOUNTAIN ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-88 SCO/9820800.WPD/003672775
-------
View looking south of concrete or steel deck arch bridge from Hoover Dam (Viewpoint 3)
View looking south of concrete or steel deck arch bridge from Lake Mead (Viewpoint 1)
142flBa 15.05 2436 04dti 300
FIGURE 3-10

SUGARLOAF MOUNTAIN ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-90 SCO/9820800.WPD/003672775
-------
^..l. 1- .-'»sk-
Existing conditions view from the rafting put-in south of Hoover Dam (Viewpoint 4)
View of steel deck arch bridge from the rafting put-in south of Hoover Dam
(Viewpoint 4)

FIGURE 3-11
GOLD STRIKE CANYON ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
142863 12.PM 243e_05atl 8W
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-92 SCO/9820800.WPD/003672775
-------
View of concrete deck arch bridge from the rafting put-in south of Hoover Dam

(Viewpoint 4)
U286312PM 2439_09>tl »96
FIGURE 3-12
GOLD STRIKE CANYON ALTERNATIVE

VISUAL SIMULATIONS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-94 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

From this viewpoint, the position, size, and presence of the concrete towers make the bridge |
a dominant feature within the photograph. Their presence is the most obvious structural
feature that would affect the view of the landscape. This bridge design is less dominant
than the steel truss rib through arch design discussed above. This bridge design would add
little diversity to the view because the diagonal cables, although visible, are not prominent.
The cables, therefore, would not detract from the view, but would maintain the view's
continuity by minimizing obstructions to the existing view of the mountains in the
background. Impacts on the visual quality of the view shown in Figure 3-5 would not be
adverse because of this bridge design. As shown in the simulation, the vividness
(memorability of the existing landscape components) would remain, and the landscape
view would remain intact. The unity (visual harmony between landscape elements) would
be affected by the structure's size and prominence, its contrasting lines, and textural
differences; however, this impact is not considered adverse.

Hoover Dam and Lake Mead would be visible to motorists traveling over the new bridge;
however, the view would be partially obstructed by the safety barrier on both sides of the
bridge. Because stopped vehicles, bicyclists, and pedestrians would be precluded from the
new bridge, the bridge would not provide the benefits of extended viewing opportunities of
Hoover Dam and Lake Mead.

Suspension Bridge from Viewpoint 1. Figure 3-5 also shows the simulated view of a |
suspension bridge crossing Lake Mead from aboard the Desert Princess on Lake Mead
(Viewpoint 1, bottom photograph). This bridge design would add a large form that exhibits |
little texture, contrasting vertical and horizontal lines, and a color contrast from the concrete
towers. I
From this viewpoint, the position, size, and presence of the concrete towers result in the |
bridge being a dominant feature. Their presence is the most obvious structural feature that
would affect the view of the landscape. Similar to the concrete cable-stayed bridge, this
design is less dominant than the steel truss rib through arch design. This design would add
little diversity to the view. The cables would not detract from the view, but maintain the
view's continuity by minimizing obstructions to the existing mountain view.

The visual quality of the view shown in Figure 3-5 would not be greatly affected by this
bridge design. As shown in the simulation, the vividness (memorability of the existing
landscape components) would remain, and the landscape view would remain intact. The
unity (visual harmony between landscape elements) would be marginally affected by the
size and prominence, contrasting lines, and textural differences of the structure.

Steel Truss Rib Through Arch Bridge from Viewpoint 2. Figure 3-7 shows a view from the |
Arizona Overlook (Viewpoint 2) looking across Lake Mead. The top photograph in that
figure shows the existing view from the overlook. The top photograph in Figure 3-8 is a
simulation showing what a steel truss rib through arch bridge would look like from this
viewpoint. This bridge design would add a large form that exhibits texture (from the steel
latticework on the arch), and contrasting lines.

SCO/CHAP3.WPD/003672775 3'95
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

From this viewpoint, the bridge is not a dominant feature that detracts from the existing
view. Although the arch is a prominent feature, the presence of the hillside in the right
foreground of the photo eliminates part of the arch. This bridge design would add to the
visual diversity of the view by intermixing horizontal, vertical, and curved lines to a view
that mixes natural and human-made elements. Because this view of the steel truss rib
through arch design would not significantly affect the backdrop of the mountains in the
background, it would not interrupt the visual continuity of the view.

Therefore, the visual quality of the view shown in Figure 3-7 would not be adversely
affected by this bridge design.

Concrete Cable-Stayed Bridge from Viewpoint 2. Also shown in Figure 3-7, from the Arizona
Overlook (Viewpoint 2) is a simulation (bottom photograph) showing what a concrete
cable-stayed bridge would look like from this viewpoint. This bridge design would add a
large form that exhibits little texture; strong diagonal, horizontal, and vertical lines; and a
color contrast from the concrete towers.

From this viewpoint, this bridge design is not a dominant feature that detracts from the
existing view. Although the bridge concrete towers are prominent features because of the
hillside in the right foreground, the other tower and remainder of the span are not visible
from this viewpoint. In addition, the cables are essentially "lost" against the background.
Similar to the suspension bridge design, this bridge design would add little diversity to the
view because the diagonal cables are not prominent. They would not detract from the view,
but would maintain the view's continuity.

Therefore, the visual quality of the view shown in Viewpoint 2 (Figure 3-7) would not be
greatly affected by this bridge design.

Suspension Bridge from Viewpoint 2. Figures 3-7 and 3-8 are the view from the Arizona
Overlook (Viewpoint 2) looking across Lake Mead. The top photograph in Figure 3-7
shows the existing view from the overlook. The lower photograph in Figure 3-8 shows how
a suspension bridge across Lake Mead would look from this viewpoint. This bridge design
would add a large form that exhibits little texture, strong horizontal and vertical lines, and a
color contrast from the concrete towers.

From this viewpoint, the bridge is not a dominant feature that detracts from the existing
view. Although the bridge's concrete towers are prominent features, because of the hillside
in the right foreground the other tower and remainder of the span are not visible from this
viewpoint. This bridge design would add little diversity to the view because the vertical
cables, although noticeable, would not detract from the view at the overlook, thus
maintaining the view's continuity. The height of the tower (below the mountain slope in
the background) would also aid in maintaining the view's continuity. Therefore, this
bridge design would not adversely affect Viewpoint 2 visual resources.

Sugarloaf Mountain Alternative (Preferred Alternative). Views of the Sugarloaf Mountain
Alternative would be unobstructed from Hoover Dam and from the rafting put-in 0.5 mile
downstream of the dam. In addition, the new bridge would be visible by aerial sightseers,
thus changing the aerial view of the dam and canyon. For some aerial viewers, this change
would detract from the lake view. This viewer group expects views to be unchanged from
existing conditions, or expects changes to be unnoticeable or unobtrusive. For others, the
bridge design would add variety to the lake view. This viewer group would notice the
visual change, but would not be offended by the change to the view.

3-96 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

As mentioned above, in anticipation of public demand for views of Hoover Dam from the
new bridge on this alignment, FHWA will study the technical feasibility of a separate
viewing facility associated with the bridge. Further details of such a facility cannot be
determined until design of the bridge and approaches is advanced beyond the current level.

Consideration of the following specific bridge designs for Sugarloaf Mountain and the other
build alternatives in this EIS is not intended to preclude other feasible structures. A Design
Advisory Panel, established as part of a Programmatic Agreement for this project under
requirements of the National Historic Preservation Act, will provide input on bridge design
concepts, structure type, and materials (see Section 3.5).

Concrete Cable-Stayed Bridge. Figures 3-9 and 3-10 are a view of Black Canyon looking
downstream from the eastern side of Hoover Dam (Viewpoint 3). As shown in the top
photograph in Figure 3-9, the view is dominated by human-made development such as the
electric transmission line towers in the foreground, and to a lesser degree, U.S. 93 and the
vehicles on the right side of the photograph. The bottom photograph simulates how a
concrete cable-stayed bridge crossing Black Canyon would look when standing atop the
dam. This bridge design would drastically alter the view by adding a large form, a variety
of lines, contrasting color, and little texture.

From this viewpoint, the bridge towers, bridge deck, and diagonal lines dominate the view.
The bridge design would add to the visual diversity of the landscape because of the
contrasting lines and colors; however, it would not add to the visual interest of the view.
The presence of the bridge would interrupt the visual continuity of the view of the one
mountain in the middleground (center of photograph) and the mountains in the
background.

The visual quality of the view shown in Figure 3-9 would be only slightly affected by this
bridge design, due to the presence of the transmission towers in the foreground. The
vividness of the view would be slightly degraded by the presence and closeness of the
bridge structure. In addition, the intactness and unity of the view would be affected by the
size and prominence of the bridge form; the vertical, horizontal, and diagonal lines; and the
textural differences between the proposed bridge and the existing landscape.

Hoover Dam and Lake Mead would not be visible to passenger cars traveling over the new
bridge. Stopped vehicles, bicyclists, and pedestrians would be precluded on the new bridge
roadway; however, FHWA will study the feasibility of a separate viewing facility associated
with the bridge.

Concrete or Steel Deck Arch Bridge. Figure 3-10 simulates how a concrete or steel deck arch
bridge crossing Black Canyon would look. This bridge design would add a large form that
exhibits little texture; vertical, horizontal, and curve Lines; and color difference (with a
concrete arch).

From this viewpoint, the position, size, and strong horizontal line created by the bridge
deck makes the bridge a dominant feature within the photograph and detracts from the
view. Visual diversity of the view would not be notably improved or degraded, except with
the contrasting color of the concrete arch. The visual continuity of the mountain in the
middleground (center of photograph) and the mountains in the background would be
decreased. The height of the bridge deck (along the top of the mountain in the
middleground) also affects the view adversely.
SCO/CHAP3.WPD/003672775 3-97
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The visual quality shown in Figure 3-9 would be only slightly affected by this bridge
design, due to the presence of the transmission towers in the foreground. The visual impact
is considered less than that discussed for the concrete cable-stayed bridge design, and the
concrete arch would have greater visual impact than steel due to the greater mass. Similar
to the concrete cable-stayed bridge, the vividness of the view would be slightly degraded by
the presence and closeness of the bridge structure. In addition, the view's intactness and
unity would be affected by the size and prominence of the bridge form; the vertical and
horizontal lines; and the textural differences between the proposed bridge and the existing
landscape.

The Sugarloaf Mountain Alternative would impact the views of Black Canyon from the
dam crest and Lake Mead. However, the Sugarloaf Mountain Alternative could be blended
into the landscape more readily than the Promontory Point Alternative. This is because (1)
the Sugarloaf Mountain alternative deck structure would form a fairly contiguous
horizontal line with the canyon rim, (2) the structure would not significantly protrude
above the horizon line when viewed from the dam crest, and (3) the structure would not
protrude above the horizon line when viewed from Lake Mead. Conversely, the
Promontory Point Alternative would be obtrusive and protrude above the strong horizontal
component of Lake Mead regardless of bridge type.

Gold Strike Canyon Alternative. Views of the Gold Strike Canyon Alternative would be
completely obstructed from Hoover Dam, the Arizona Overlook, and Lake Mead. The new
bridge would be visible from the rafting put-in 0.5 mile downstream of Hoover Dam and by
aerial sightseers. The bridge at this location would also change the landscape setting of
Gold Strike Canyon as seen from the hiking trail and hot springs. For some viewers at the
river launch and those seeing the area by air, this change would detract from the view. For
other viewers, the bridge design would add variety to the view. It should be noted that the
view of the bridge from rafts floating down river from the rafting launch would increase as
the rafters float toward the bridge. Once downstream of the bridge, views of the bridge
would again decrease. Views by recreationists using the hiking trail or hot springs would
be adversely affected by this alternative, regardless of the bridge design selected.

Steel Deck Arch Bridge. Figures 3-11 and 3-12 show a view of Black Canyon looking
downstream from the rafting put-in located 0.5 mile south of Hoover Dam. The top
photograph in Figure 3-11 is the existing view from the put-in. The bottom photograph
simulates how a steel deck arch bridge would look from the put-in. This bridge design
would add a large form; contrasting horizontal, vertical, and curved lines; unobtrusive
color; and texture changes to the view.

From this viewpoint, the existing landscape appears largely undisturbed. The only
noticeable human-made feature is the retaining wall in the upper right corner of the
photograph. The position, size, and shape of the bridge structure make it a feature that
would dominate the view from a raft. The structure would add to the visual diversity of the
view. The bridge structure would not interrupt the visual continuity of the mountains in
the background, and it would not affect the view of the slopes in the middleground.
3-98 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The visual quality shown in Figure 3-11 would be affected by this bridge design; although,
of the two bridge designs being considered for this alternative, it is the less obtrusive
design. The vividness of the landscape components would not be adversely affected by the
bridge structure; however, the view's intactness and unity would be slightly compromised
by the size and prominence of the form and contrasting lines.

Concrete Deck Arch Bridge. Figure 3-12 simulates how a concrete deck arch bridge would
look. Similar to that discussed for the steel deck arch bridge, this bridge design would add
a large form; contrasting horizontal, vertical, and curved lines; unobtrusive color, and
texture changes to the view. As the simulation shows, these effects would be more
pronounced with this bridge design than that for the steel deck arch bridge.

This design would have the same effect on the visual dominance, diversity, and continuity
of the view as was described for the steel deck arch bridge. In addition, this bridge design
would affect the view's vividness, intactness, and unity in the same manner; however, these
effects would be more pronounced with this bridge design.

This bridge design would affect the quality of the view shown in Figure 3-11 in the same
manner as that described for the steel deck arch bridge. Because the concrete forms on this
bridge are larger than the steel shown in the steel deck arch bridge, the visual impact from
this bridge design is greater than that for the steel deck arch bridge.

No Build Alternative. Implementing the No Build Alternative would result in no additional
roadway or bridge being constructed, and would therefore result in no physical changes to
the existing roadway and Hoover Dam crossing. No change to the views currently
experienced by recreationists visiting the Hoover Dam area (including the dam, Lake Mead,
Colorado River, Black Canyon, and Gold Strike Canyon hiking trail and hot springs) is
expected. Aerial views would also be unaffected by this alternative.

As traffic levels continue to increase, vehicle speeds on the dam are expected to decrease,
resulting in longer views for through-traffic drivers and passengers. Although the view
duration would be increased for this viewer group, the quality of the view would remain
obstructed (either by vehicle height or by the vehicle itself). In addition, as noted
previously, the focus of this viewer group is not its surroundings but primarily its
concentration on negotiating through traffic, avoiding pedestrians, and reaching its final
destination. Therefore, this is not considered a benefit to this viewer group.

3.7.3 Measures to Minimize Harm

Visual simulations were created to illustrate the impacts to visual resources from each of the
three build alternatives. Figure 3-4 shows the viewpoints for the visual simulations.
Figures 3-5 through 3-12 are visual simulations for each alternative.

3.7.3.1 Construction Mitigation
Regardless of the alternative selected, certain views during the construction period would
be altered by the presence of construction vehicles, equipment, personnel, and emerging
new highway facilities. This impact is expected to be considered adverse by some viewers
and is an unavoidable consequence of project construction.

The following mitigation measure will be implemented to reduce impacts on visual
resources: implement a public information program that could include an Internet web site,
and provide data sheets to Hoover Dam visitors. Information to be provided includes a

SCO/CHAP3.WPD/003672775 3-"
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

description of the proposed project, the purpose and need, a construction schedule, and an
explanation of what viewers are seeing and what can be expected to be seen in the future.
A visual simulation will be included so that the viewer can see what the constructed project
will look like when complete. Providing project information may alleviate viewers'
concerns about construction-related view obstruction by explaining that the project is
intended to improve traffic continuity and visitor safety.

3.7.3.2 Operational Mitigation

Regardless of the alternative selected, the proposed bridge would alter the view, either from
Hoover Dam, Lake Mead, the river rafting put-ins, or the Gold Strike Canyon hiking trail
and hot springs. For all the alternatives, the rock cuts adjacent to the proposed bridge will
be engineered to minimize impacts on visual resources. This could include special blasting
techniques to avoid pre-split shear rock faces. Resulting ledges will be topsoiled and
revegetated to the extent possible. Rock slopes and slope protection in the vicinity of the
bridge will be stained with a desert varnish to reduce the visual impact from the proposed
construction adjacent to the bridge.

Promontory Point Alternative. Impacts on visual resources from the steel truss rib through
arch bridge could be lessened by coloring the steel to blend with the surrounding
environment.

To reduce impacts on visual resources from the concrete cable-stayed bridge and the
suspension bridge, the concrete should be tinted to blend with the surrounding
environment, which would reduce the visibility of the towers.

Sugarloaf Mountain Alternative (Preferred Alternative), impacts on visual resources from the
concrete cable-stayed bridge, if selected, will be reduced by tinting the concrete with a
nonglare color that blends with the surrounding environment. However, the closeness of
the bridge to the dam would still result in the bridge dominating the downstream view
from the dam.

Although the computer simulation is conceptual in Figure 3-10, impacts on visual resources
from the concrete or steel deck arch bridge could be lessened by setting the bridge deck
elevation so that the mountain in the center of the photograph would be more prominent.
However, this may not be feasible from an engineering design, earthwork, or economic
standpoint. If not, the view will remain affected, but is not considered adverse because of
the visual intrusion of the transmission line towers in the foreground. If either a concrete or
steel arch bridge design is selected, the impact may be lessened by coloring the structure to
blend with the surrounding environment.

Gold Strike Canyon Alternative. Impacts on visual resources from either the concrete deck
arch bridge or the steel deck arch bridge would be reduced by coloring the concrete or steel
so that the bridge blends more effectively with the surrounding environment. This measure
would reduce the visual impact perceived by the hikers, hot spring users, rafters, and other
river users near the proposed alignment.

3.8 Recreation Resources

3.8.1 Affected Environment

Hoover Dam, about 1,244 feet long and 726 feet tall, is situated in Black Canyon and is one
of the most spectacular structures in the world. It is an NHL and a popular tourist

SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

attraction in southern Nevada and northern Arizona. Reclamation operates a visitor center
at the dam, offers daily guided tours, provides parking for 851 personal vehicles and
22 buses (a multistory parking garage and an outdoor parking lot are adjacent to and on the
dam), and has several scenic overlooks providing photograph opportunities (personal
communication with Dan Jensen/Reclamation, 1998). Photography is a very popular
activity at the dam because of the dam's historic significance and its massive size. In
addition, souvenir shops and restrooms are available.

Three food and beverage concessionaires were located at the dam until a fire destroyed the
one located at the Arizona Lookout. Plans to relocate the two remaining concessions (one in
Nevada and the other in Arizona) to the lower level of the multistory parking garage are
nearly complete. The third concession at the Arizona Lookout has been rebuilt. The
existing concession building on the Nevada side of the dam may be converted into a
museum and is currently under study. The existing Arizona-side concession trailer will be
removed from the site early in 2001 (personal communication with Dan
Jensen/Reclamation, 2000).

About 33.2 million visitors have toured Hoover Dam since 1937. There were about
1.03 million visitors in 1997 and an average of 2,823 persons daily in 1997 (personal
communication with Kris Mills/Reclamation, 1998). Public access to the downstream side
of the dam and Colorado River for 0.5 mile is precluded for safety reasons. The area is
fenced in certain locations, and warning signs are posted. This area is accessible only to
dam personnel and those having Reclamation permits.

The LMNRA had 9.7 million visitors in 1997 (personal communication with Bill
Burke/NPS, 1998). Six developed recreation areas are on Lake Mead, with day-use areas,
boating facilities, campgrounds, and lodging. In addition, Lake Mead Cruises operates a
boat tour aboard the Desert Princess, a paddlewheel boat with a capacity of several
hundred people. Sightseeing is the most popular activity; other activities include fishing,
boating, houseboating, parasailing, scuba diving, jet skiing, swimming, canoeing, kayaking,
hiking, and nature study.
The developed recreation area on Lake Mead nearest to the proposed project is Boulder
Beach, located on the western arm of Lake Mead. Boulder Beach can be accessed from
U.S. 93/95 in Henderson via Lake Mead Drive and from Nevada SR166 (Lakeshore Drive).
Facilities at Boulder Beach include a marina, camping areas, picnic areas, a swimming
beach, lodging, two launch ramps, store and restaurant, boat gasoline station, restrooms,
and parking areas (personal communication with Bill Burke/NPS, 1998).

The Hacienda Hotel, located on U.S. 93 about 3 miles west of Hoover Dam, provides
gaming, lodging, and eating facilities. About 0.5 mile downstream from Hoover Dam, a
rafting concessionaire (Black Canyon Raft Tours) operates a dock with a fleet of 11 rafts that
accommodate from 18 to 42 people each and are used to float customers down the Colorado
River. About 18,500 customers floated the river in 1997. The rafting concession operates
from February 1 to November 30, and by special arrangement in December and January
(personal communication with Ron Opfer/Black Canyon Raft Tours, 1998). It has a permit
to use Reclamation's restricted access road (the Lower Portal Road) from U.S. 93 down to
the river (personal communication with Dan Jensen/Reclamation, 1998).

Reclamation also issues permits to individuals to launch canoes at a put-in about 20 yards
downstream of the rafting put-in. Groups of up to 15 people are escorted twice daily from
Reclamation's warehouse to the river put-in via Lower Portal Road. Demand for this

SCO/CHAP3.WPD/003672775 3'101
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

service exceeds capacity; the service usually requires advance reservations. In 1997,
7,212 individual permits were issued for this service (personal communication with Dan
Jensen/Reclamation, 1998).

In addition, in February 1998 a tour group was issued an annual permit by Reclamation to
escort groups from Las Vegas to tour Hoover Dam and provide access to Lower Portal Road
to photograph the dam from the helicopter pad and canoe put-in. To date, the average
number of users has been 10 per week (personal communication with Dan
Jensen/Reclamation, 1998).

A 2.5-mile-long trail is used by visitors to hike through Gold Strike Canyon to the Colorado
River and hot springs. The Gold Strike Canyon trail is not an official NFS-designated trail.
The trail is used for nature study, photography, technical rock climbing, and accessing the
hot springs. An estimated 1,000 hikers use the trail and hot springs annually, mostly in the
cooler months (personal communication with Jim Holland/NPS, 1998). To accommodate
the needs of hot springs users, the NFS provides a portable toilet at the canyon mouth.

Historic railroad grades and tunnels near Hoover Dam are currently used for hiking and
mountain biking. The NFS, in partnership with Reclamation, the City of Boulder City, and
the Southwest Gas Trailhikers, have developed a proposal to convert these existing railroad
grades to a hiking/bicycle trail under the Intermodal Surface Transportation Efficiency Act
(ISTEA) of 1991. The historic railroad grades were constructed in 1931 for moving materials
and equipment to the Hoover Dam construction site. The planned trail will extend from
Boulder City to Hoover Dam, a distance of 8 miles, and will serve as an extension of the
Hemenway Wash Trail that was constructed by Boulder City. The development of this trail
is being supported financially with matching funds from the City of Boulder City and the
Southwest Gas Trailhikers.

Commercial airplane and helicopter sightseeing flights originating in Las Vegas and nearby
small airports and helipads also are available to recreationists wanting aerial views of
Hoover Dam, Lake Mead, and the Colorado River.

3.8.2 Environmental Consequences

3.8.2.1 Construction Impacts
Impacts during construction of the proposed project common to all three build alternatives
include the following:

• Dust would be emitted from earthmoving activities, construction vehicles and
equipment, construction worker vehicles, material delivery vehicles, and from areas
within the construction zone that have been disturbed or where excavated material is
stockpiled. The magnitude of the impact on recreationists visiting Hoover Dam, Lake
Mead, the Colorado River, and Gold Strike Canyon hot springs and hiking trail would
vary by alternative.

• Noise would be emitted during all construction phases. Noise sources include
construction vehicles and equipment, construction worker vehicles, and materials
delivery vehicles. Noise levels associated with construction activities are typically
88 dBA to 92 dBA at a distance of 50 feet, which would be a noticeable change from
ambient noise levels. The magnitude of the impact on recreationists visiting Hoover
Dam, Lake Mead, Colorado River, hot springs, and the hiking frail would vary by
alternative.

3-102 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Effects on water-dependent recreation activities would occur from construction work at
Lake Mead near Hoover Dam and at the Colorado River rafting and canoeing put-ins
because of the temporary impacts on access and water quality (this would apply only to
the Promontory Point and Sugarloaf Mountain Alternatives).

• Effects on access to Hoover Dam, Lake Mead, the Colorado River, and the hiking trail in
Gold Strike Canyon would occur because of proposed project construction activities.
Roadway access and the access to Hoover Dam from Lake Mead may be restricted at
times during construction to ensure the public's safety. The canyon trail would be
closed during construction if the Gold Strike Canyon Alternative were selected.

• Effects of the presence of construction equipment would occur. For some recreationists,
the presence of construction equipment and its associated activities would detract from
the recreational experience. For others, the presence of equipment and construction
activities would be interesting, creating additional photographic opportunities.

• Increased light emitted from the construction area would occur if nighttime
construction is conducted. Hoover Dam is currently lit at night and provides interesting
nighttime views for tourists. For some recreationists, the additional light that would be
emitted during nighttime construction, if it occurs, would detract from the nighttime
views experienced during the dam visit. Again, depending on their values and
expectations, for other recreationists the additional light and associated construction
activities would add interest to the setting. This issue would be less of a concern to
recreationists if the Gold Strike Canyon Alternative were constructed because that
alternative is not visible from Hoover Dam. However, the canyon downstream might
appear brighter during nighttime construction, if that alternative were selected.

Impacts specific to the three build alternatives and the No Build Alternative are described
below.

Promontory Point Alternative. Construction of the Promontory Point Alternative would last
approximately 5 years. During construction of this alternative, an area of Lake Mead
upstream of Hoover Dam would be designated as a construction safety zone. This
designation would limit public use of that area of the lake for recreational activities by
eliminating access to Hoover Dam on its upstream side (from Lake Mead). Access
restrictions and periods of closure would be coordinated with NFS and the lake tour
operators (e.g., the Desert Princess tour concessionaire). No other effects on activities at
Lake Mead would be expected.

Existing recreational activities at Hoover Dam, the Colorado River, Gold Strike Canyon
hiking trail and hot springs, and the Hacienda Hotel would not be affected by construction
of this alternative. In addition, the ground and aerial tour groups would not be affected.

In areas where blasting, earthmoving, other construction activities, and spoil disposal areas
are located, construction safety zones would also be established. These zones would
preclude using the area for hiking or other dispersed recreational activities currently
occurring along the alignment.

Sugarloaf Mountain Alternative (Preferred Alternative). Construction of the preferred
Sugarloaf Mountain Alternative is expected to last approximately 5 years. Certain areas
along the Colorado River and along U.S. 93 would be designated as construction safety
zones. These designations would preclude public use of those areas for recreational
activities. The rafting concession and the canoeing put-in should be able to continue to
SCO/CHAP3.WPD/003672775 3'103
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

operate with minor interruptions in service by coordinating launching to avoid conflicts
with construction activities. Access to the river put-in and helipad by ground tours may be
interrupted by construction activities; coordination should occur to avoid conflicts with
such activities.

Existing recreational activities at Lake Mead, Hoover Dam, Gold Strike Canyon hiking trail
and hot springs, and the Hacienda Hotel would not be affected by construction of the
proposed project. In addition, ground and aerial tour groups would not be affected by
construction of this alternative.

In areas where blasting, earthmoving, other construction activities, and spoil disposal areas
are located, construction safety zones would be established. These zones would preclude
using the area for hiking or other dispersed recreational activities currently occurring along
the proposed alternative.

Gold Strike Canyon Alternative, Construction of the Gold Strike Canyon Alternative would
last approximately 5 to 6 years. Certain areas along ttie Colorado River and US. 93 would
be designated as construction safety zones. These designations would preclude public use
of those areas for recreational activities. The Gold Strike Canyon hiking trail would be
dosed during construction. The rafting concession and the canoeing put-in should be able
to continue to operate with minor interruptions in service by coordinating launching and
passage through the construction zone to avoid conflicts with construction activities.

Existing recreational activities at Lake Mead, Hoover Dam, and the Hacienda Hotel would
not be affected by construction of this alternative. In addition, aerial tour groups would not
be affected.

No Build Alternative. Because the No Build Alternative would result in the proposed project
not being constructed, no construction-related impacts on existing recreational activities are
expected at Hoover Dam, Lake Mead, Colorado River put-ins, Gold Strike Canyon hiking
trail and hot springs, Hacienda Hotel, and ground or aerial tours.

3.8.2.2 Operational Impacts
Impacts during the operational phase of the proposed project common to all three build
alternatives include the following:

• The new bridge, regardless of the alternative chosen, would likely become a tourist
attraction because of its association with and proximity to Hoover Dam, its design, and
the setting in which it would be located. This would result in recreationists in the area
making it a travel destination. This is considered a benefit to recreationists desiring the
experience.

• For some recreationists, the presence of the new bridge would detract from the
recreational experience offered at Hoover Dam by changing the view from the dam. For
other recreationists, the presence of the new bridge would add to the variety of the view
from the dam, which they would consider to be interesting, thus creating additional
photographic opportunities. (The view from the dam would change with either the
Promontory Point Alternative or Sugarloaf Mountain Alternative.)
3-104 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Because traffic congestion would be alleviated at Hoover Dam, CO and VOC daily
emissions are expected to be reduced by approximately 50 percent and 80 percent,
respectively. Pedestrian safety would also be improved. This is considered a benefit to
recreationists atop the dam.

Impacts specific to the three build alternatives and the No Build Alternative are described
below.

Promontory Point Alternative. The new bridge would be visible from Hoover Dam and from
aerial sightseeing recreationists, thus changing the recreational setting of Lake Mead from
the dam and the air. For some recreationists, this change would detract from the lake view.
For other recreationists, the bridge design would add variety to the lake view. The presence
of the new bridge would not preclude recreational opportunities currently offered at
Hoover Dam and by aerial sightseeing.

The bridge would also be visible to recreationists on Lake Mead (those in motorized and
nonmotorized water craft, anglers, and swimmers) and along adjacent shores (e.g., hikers
and picnickers) in the dam vicinity. Similar to that discussed for views from Hoover Dam
and the air, the quality of the recreational experience of some recreationists on and around
Lake Mead would be degraded, and the experience of other recreationists would be
enhanced by the presence of the new bridge. The new bridge would not preclude
recreational opportunities currently offered by Lake Mead and its shores. No significant
changes to existing noise levels are expected.

Because traffic would be diverted from atop Hoover Dam to the new bridge, traffic
congestion would be reduced, thereby reducing the potential for vehicle collisions with
pedestrian tourists on the dam. The reduction in traffic would also reduce the amount of
truck traffic noise and volume of air pollutants emitted from vehicles on the dam. These
three improvements are considered benefits to recreationists visiting Hoover Dam.

Hoover Dam may also be visible to motorists traveling over the new bridge and
approaches; however, the safety barrier and the high elevation of the proposed bridge
(relative to the dam) will minimize viewing opportunities. Because stopped vehicles,
bicyclists, and pedestrians would be precluded from the new bridge, additional
opportunities to photograph Hoover Dam would not be provided.

Implementation of the Promontory Point Alternative, on its current alignment, would
impact the planned railroad grade hiking/bicycle trail. Because the alignments for both the
Promontory Point Alternative and the railroad grade trail are preliminary and have not
been finalized, there would be an opportunity for NFS and FHWA to work collaboratively
to develop a compatible design for the two facilities. This collaboration in the design of
these two transportation facilities would ensure the railroad grade trail would not be
adversely affected by subsequent development of the U.S. 93/Hoover Dam Bypass.

Implementation of the Promontory Point Alternative would not affect other recreational
activities at the Colorado River, the Gold Strike Canyon hiking trail and hot springs, or the
Hacienda Hotel.

Sugarloaf Mountain Alternative (Preferred Alternative). The new bridge would be visible from
Hoover Dam and from aerial sightseeing tours, thus changing the recreational setting of the
Colorado River immediately downstream of the dam from both the dam and the air. For
some recreationists, this change would degrade the river view. For other recreationists, the
bridge design would add variety to the river view. The presence of the new bridge would

SCO/CHAP3.WPD/003672775 3-105
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

not preclude the recreational opportunities currently offered by Hoover Darn and aerial
sightseeing.

The bridge would be visible to recreationists on the Colorado River at the rafting and
canoeing put-in locations, located about 0.5 mile downstream of Hoover Dam. The quality
of the recreational experience of some recreationists on the Colorado River would be
degraded, and the experience of other recreationists would be enhanced by the presence of
the new bridge. The new bridge would not preclude recreational opportunities currently
offered at the rafting and canoeing put-ins or at the hot springs and hiking trail. As rafters
and canoeists float downstream away from the proposed bridge, the view of the bridge
would diminish, until approximately 0.4 mile downstream from the put-in, at which point
the bridge would not be visible. No significant changes from existing noise levels are
expected.

Because traffic would be diverted from atop Hoover Dam to the new bridge, traffic
congestion would be reduced, thereby reducing the potential for vehicle collisions with
pedestrian tourists on the dam. The reduction in traffic would also reduce the amount of
truck traffic noise and volume of air pollutants emitted from vehicles on the dam. These
three improvements (pedestrian safety, noise, and air quality) are considered benefits to
recreationists visiting Hoover Dam.

Hoover Dam may also be visible to motorists traveling over the new bridge and
approaches; however, the safety barrier and the high elevation of the proposed bridge
(relative to the dam) will minimize viewing opportunities. Stopped vehicles, bicyclists, and
pedestrians would be precluded on the new bridge roadway; however, FHWA will study
the feasibility of a separate viewing facility associated with the bridge.

Implementation of the Sugarloaf Mountain Alternative, on its current alignment, would
impact the planned railroad grade hiking/bicycle trail. Because the alignments for both the
Sugarloaf Mountain Alternative and the railroad grade trail are preliminary and have not
been finalized, there is an opportunity for NFS and FHWA to work collaboratively to
develop a compatible design for the two facilities. Since Sugarloaf Mountain is the
preferred alternative, this design collaboration would ensure the railroad grade trail would
not be adversely affected by the U.S. 93/Hoover Dam Bypass.

Implementation of the Sugarloaf Mountain Alternative would not affect other recreational
activities at Lake Mead, the Gold Strike Canyon hiking trail and hot springs, and the
Hacienda Hotel.

Gold Strike Canyon Alternative. The new bridge would not be visible from Hoover Dam or
by the ground tours; therefore, those activities would not be affected. It would be visible to
aerial sightseeing recreationists, thus changing the recreational setting of Black Canyon and
the Colorado River in the vicinity of the construction zone from the air. For some
recreationists, this change would degrade the river view. For other recreationists, the
bridge design would add variety to the river view. The presence of the new bridge would
not preclude aerial sightseeing opportunities.

The location where the bridge would cross the river would be visible to recreationists at the
rafting and canoeing put-in locations, located about 0.5 mile downstream of Hoover Dam.
It would be visible to recreationists using the hot springs and hiking trail. For some
recreationists, the quality of the recreational experience in Black Canyon, on the Colorado
River, and at the hiking trail and hot springs would be degraded. The presence of the new
bridge would not preclude recreational opportunities currently offered at the rafting and
3-106 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

canoeing put-ins or at the hot springs and hiking trail. After put-in, rafters and canoeists
would float downstream toward the proposed bridge, resulting in the bridge becoming
increasingly large. Once downstream of the bridge, it would remain visible for
approximately 0.8 mile.

The addition of vehicle traffic to the currently undeveloped Gold Strike Canyon would
increase existing ambient noise levels by 26 dBA. With construction of noise barriers on the
roadway, noise levels along the canyon trail would still represent a substantial increase over
existing levels, which would be an adverse impact. This increase in noise levels and the
bridges and highway in the canyon would affect the quality of the recreational experience
of users of the hiking trail in that area (see Chapter 6, Section 4(f) Evaluation).

Because traffic would be diverted from atop Hoover Dam to the new bridge, traffic
congestion on the dam would be reduced, thereby reducing the potential for vehicle
collisions with pedestrian tourists on the dam. The reduction in traffic would also reduce
the amount of truck traffic noise and volume of air pollutants emitted from vehicles on the
dam. These three improvements are considered benefits to recreationists visiting Hoover
Dam.

Implementation of the Gold Strike Canyon Alternative would not affect recreational
activities at Lake Mead and the Hacienda Hotel.

No Build Alternative. Implementation of the No Build Alternative would result in no
additional roadway or bridge being constructed, and would result in no physical changes to
the existing roadway and Hoover Dam crossing. Traffic levels on U.S. 93 are projected to
continue to increase, and the number of recreationists visiting Hoover Dam, Lake Mead,
and the Colorado River and its environs is also expected to continue to increase. The
continued increase in vehicles along U.S. 93 near Hoover Dam and atop the dam is expected
to further increase traffic congestion.

Increased traffic would result in increased travel times for both through-vehicles and
vehicles whose final destination is the dam, and would also result in additional noise and
vehicle fumes on the roadway and atop the dam. Increased travel times may affect the
enjoyment of the travelers' recreational experience, and the visit to Hoover Dam would
likely be degraded by associated additional noise and vehicle fumes.

Additional traffic would increase the potential for vehicle and pedestrian collisions on the
dam, resulting in an increased public safety hazard. Continuing to allow commercial trucks
to cross the dam, in combination with the expected increased traffic levels, would also
increase the public safety hazard. The increase in recreationists visiting the dam would
compound this public safety hazard. This increased hazard potential would adversely
affect the recreational experience at the dam.

Implementation of the No Build Alternative would not adversely affect Lake Mead
recreational activities. However, if traffic congestion increases to intolerable levels to
motorists, they may elect to drive to their destination using an alternate route, even if it is
longer. Motorists who chose an alternate route would forego the recreational opportunities
offered at Hoover Dam, the Colorado River, the Gold Strike Canyon hiking trail and hot
springs, and the Hacienda Hotel.
SCO/CHAP3.WPD/003672775 3-107
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENT At. CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.8.3 Measures to Minimize Harm

3.8.3.1 Construction Mitigation
Regardless of the alternative selected, certain areas would be designated for construction
activities, which would preclude using those areas for dispersed recreational activities. In
most cases, this impact on recreational activities is not considered adverse. Designated
construction safety zones and construction areas would have signs posted, and public
access to those areas would be precluded, thus reducing the potential for recreationists to be
injured in the construction zone or by construction activities. The hiking trail in Gold Strike
Canyon would be dosed during construction of the Gold Strike Canyon Alternative, which
would be an adverse impact on the recreationists using this area.

Promontory Point Alternative. The following mitigation measures should be implemented:
• Construction activities should be coordinated with Lake Mead Cruises to avoid
conflicts.
• The construction zone within Lake Mead should be marked with buoys, or other
devices, to preclude access by private and commercial boats.

Sugarloaf Mountain Alternative (Preferred Alternative). Raft and canoe launchings at the put-
ins on the Colorado River will be scheduled to avoid conflicts between construction
activities and put-ins.

Gold Strike Canyon Alternative. The following mitigation measures should be implemented:
• Raft and canoe launchings at the put-ins on the Colorado River, and floating through
the construction zone, should be scheduled to avoid conflicts between construction
activities and river floating.
• A net or other device should be used to prevent construction materials or equipment
from falling from the bridge into the river.
• The loss of trail access from U.S. 93 to the hot springs during the construction period is
considered unmitigable.

3.8.3.2 Operational Mitigation
Recreational activities at Hoover Dam, Lake Mead, and the Colorado River would not be
precluded by implementation of any of the three build alternatives. Selection of the
Sugarloaf Mountain Alternative would alter the view from Hoover Dam and the river put-
ins.

Promontory Point Alternative. No additional mitigation for this alternative is required or
recommended.

Sugarloaf Mountain Alternative (Preferred Alternative). Based on recommendations of the
DAP to reduce visibility of the bridge from recreational viewpoints, the bridge could be
painted or tinted with nonglare colors that blend with the surrounding environment. No
additional mitigation for this alternative is required or recommended.

In anticipation of public demand for views of Hoover Dam from the new bridge on this
alignment, FHWA will study the technical feasibility of a separate viewing platform
associated with the bridge. Further details of such a facility cannot be determined until
design of the bridge and approaches is advanced beyond the current level.

3-108 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Gold Strike Canyon Alternative. Noise levels resulting from operation of this alternative
were calculated to be 65 dBA-L^at the top of the hiking trail, compared against an existing
noise level of 39 dBA in the canyon. The federal/state noise criterion or standard to be
achieved is 67 dBA-L^. It would be possible to reduce the noise levels by constructing noise
barriers located at the outside edge of the roadway adjacent to the trail (shown on
Figure 3-1). A 6 dBA-L^ reduction could be achieved, resulting in a noise level of 59 dBA.
Although the barriers would reduce the noise level below the federal/state criterion, the
resulting noise level still represents a substantial increase over existing conditions. Reduced
access for hikers and aesthetic impacts from the elevated roadway in the canyon also cannot
be mitigated.

3.9 Socioeconomics

3.9.1 Affected Environment

This section describes the population, employment, and income levels in Clark County and
Boulder City, Nevada and Mohave County, Arizona. Boulder City is the nearest town to
the proposed project area and is, therefore, the focus of the discussion. This section also
discusses social conditions, environmental justice, and transportation and circulation.

3.9.1.1 Population
The Hoover Dam area is located within Clark County, Nevada, and Mohave County,
Arizona. Clark County, in southern Nevada, covers 7,911 square miles and has a
countywide population density of 125 people per square mile. The 1996 population was
992,593, an increase of 34 percent over 1990. The Las Vegas and Henderson population of
560,359 represents approximately 48 percent of Clark County's total population.

Mohave County, in western Arizona, covers 13,312 square miles with a countywide
population density of 9 people per square mile. Between 1990 and 1996, population
increased by 30 percent, to 121,602.

Boulder City is situated along the eastern border of Clark County, about 24 miles southeast
of Las Vegas and 6 miles southwest of Hoover Dam. Boulder City's population has grown
more slowly than the rest of the county because of its controlled growth ordinance. Current
population is approximately 14,500.

3.9.1.2 Employment
Tourism is a primary economic force in Clark County. Boulder City offers a full range of
services to the increasing numbers of tourists, with motels, restaurants, and an airport.
Although gambling is not permitted within the city, Hacienda Hotel (located on U.S. 93
between Boulder City and Hoover Dam), a major employer in the area, offers gaming and
other entertainment. Federal and local government agencies are the most significant
employers in the local labor force. In addition to tourism and government, a light industrial
area in the city provides commercial and manufacturing jobs to the local economy.

Construction, trade, finance, real estate, and services provide the majority of employment in
Mohave County. Employment opportunities at Hoover Dam consist of federal jobs and
privately operated food and gift concessionaires.
SCO/CHAP3.WPD/003672775 3-109
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

In 1989, average personal per capita income in Boulder City was $17,231; Clark County was
$15,109; and the State of Nevada was $15,214. The national personal per capita income was
$14,420.

3.9.1.3 Social Conditions
The proposed project is located entirely on federal land about 6 miles northeast of the
nearest residential area in Boulder City. Boulder City is the only city in Nevada where
gambling is prohibited. The city has also instituted a controlled growth policy to prevent
rapid development and to preserve the utility systems and social infrastructure. Boulder
City offers a quiet, small town atmosphere.

3.9.1.4 Environmental Justice
Environmental justice refers to social inequity in bearing the burdens of adverse
environmental impacts. Certain U.S. socioeconomic groups, including ethnic minorities,
the elderly, rural residents, and others, have historically experienced a disproportionate
share of adverse effects from locally undesirable land uses such as toxic waste dumps,
landfills, and freeway projects.

Consistent with Title VI of the 1964 Civil Rights Act and Executive Order 12898, Federal
Actions to Address Environmental Justice in Minority Populations and Low Income Populations,
dated February 11,1994, all proposed projects and decisions must ensure that minority and
low-income populations are not disproportionately adversely affected by transportation
programs or projects.

The FHWA policy toward environmental justice is to address whether any social group is
disproportionately impacted by a proposed project, and to identify possible mitigation
measures to avoid or minimize adverse social impacts. Specifically, the FHWA intends that
no person in the U.S. shall, on the grounds of race, color, or national origin, be excluded
from participation in, be denied the benefits of, or be subjected to discrimination under any
program or activity receiving federal financial assistance.

Table 3-19 presents 1990 census data for Las Vegas, Henderson, and Boulder City, Nevada;
and for Kingman, Arizona.

Table 3-19
1990 Census Data by Locality Near the Proposed Project Area
Las Vegas •
Total Population
258,295
Race (Percent)
White: 78.4
Black: 11. 5
Al": 0.9
Ab: 3.6
Other*: 5.6
Henderson

64,942

White: 91.5
Black: 2.7
Al: 1.0
A: 2.1
Other: 2.7
Boulder City

12,567

White: 97
Black: 0.4
Al: 1.0
A: 1.2
Other: 0.4
Kingman

12,722

White: 94.5
Black: 0.1
Al: 1.3
A: 1.5
Other: 2.6
3-110 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-19
Las Vegas
Total Households
99,954
Race (Percent)
White: 82
Black: 10.1
At: 0.9
A: 2.6
Other 4.2
Households by Age Group
<25: 5,904
25-34: 24,401
35-44: 22,469
45-54: 16,431
55-64: 13,510
65-74: 11.903
Henderson

23,353

White: 92.7
Black: 2.7
Al: 1.0
A: 1.4
Other: 2.2

<25: 1,288
25-34: 6,019
35-44: 6,059
45-54: 3,846
55-64: 2,876
65-74: 2.422
Boulder City

5,116

White: 98
Black: 0
Al: 1.0
A: 0.7
Other 0.3

<25: 104
25-34: 616
35-44: 874
45-54: 880
55-64: 888
65-74:1.092
Kingman

4,961

White: 95
Black: 0.2
Al: 1.1
A: 1.2
Other: 2.5

<25: 210
25-34: 849
35-44: 967
45-54: 800
55-64: 772
65-74: 807
Households (all races) Age 55 and Over and
Percentage Below the Poverty Level
30,749
(52 Percent)
Households Age 55 and Over Below
the Poverty Level" by Race" (Percent)
White: 50.5
Black: 63.8
Al: 65.1
A: 60.1
Other 51.4

6,141
(46 Percent)

White: 45.7
Black: 48.4
Al: 24.5
A: 32.4
Other: 71.7

2,642
(45 Percent)

White: 23.5
Black: 0
Al: 12.8
A: 21 .4
Other 0

2,135
(65 Percent)

White: 64.3
Black: 100
Al:41.1
A: 100
Other: 100
Families Above the Poverty Level In 1 989 by Race (Percent)
White: 76.3
Black: 7.9
Al: 0.9
A: 2.8
Other: 4.0
White: 88.2
Black: 2.1
Al: 0.8
A: 1.3
Other: 2.5
White: 93.5
Black: 0
Al: 1.3
A: 0.4
Other 0.3
White: 89.2
Black: 0.2
Al: 1.4
A: 1.2
Other: 2.5
Families Below the Poverty Level in 1989 by Race (Percent)
White: 4.6
Black: 2.4
Al: 0.1
A: 0.2
Other: 0.8
Per Capita Income by Race in 1989 ($)
White: 16,121
Black: 9,252
Al: 12,140
A: 12,465
Other: 8.436
White: 4.4
Black: 0.4
Al: 0.1
A: 0.1
Other: 0.1

White: 16,951
Black: 11,691
Al: 11,008
A: 10,846
Other: 9.773
White: 4.5
Black: 0
Al: 0
A: 0
Other: 0

White: 17,254
Black: 1,096
Al: 13,788
A: 26,219
Other: 9.712
White: 5.2
Black: 0
Al: 0
A: 0.2
Other: 0.1

White: 12,370
Black: 10,400
Al: 10,480
A: 37,571
Other: 12.523
SCO/CHAP3.WPD/003672775
3-111
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Table 3-19
1990 Census Data by Locality Near the Proposed Project Area
Las Vegas Henderson Boulder City Kingman
a Al—American Indian, Eskimo, or Aleut
" A—Asian or Pacific Islander
0 Other—Other Race
" FHWA defines low income as a median household income of less than $15,150 for a family of four.
Numbers presented in this table are conservative because they include the household income category of
$15,000 to $24,999 to ensure including those households with household income between $15,000 and
$15,150.
e These numbers show, for example, that 50.5 percent of all white households age 55 and over are below
the poverty level in Las Vegas, Nevada.
Source: 1990 U.S. Census Data

3.9.1.5 Transportation and Circulation
U.S. 93 is a north-to-south trending highway with the southern terminus at Wickenburg,
Arizona (northwest of Phoenix). U.S. 93 intersects 1-15 in Las Vegas and heads north near
the eastern boundary of Nevada, bisects Idaho, and continues north through western
Montana to the Canadian border. This route is used by traffic from Tucson and Phoenix,
Arizona; to Las Vegas and Reno, Nevada; and Salt Lake City, Utah. Usage has increased
since NAFTA implementation. The U.S. 93 corridor, in combination with other highways,
creates a continuous north-to-south corridor between Canada and Mexico, through the
United States from Calgary, Canada, to Nogales, Mexico (Figure 1-1). These highways,
consisting mostly of four-lane divided facilities with structural sections capable of
supporting heavy vehicles, provide north-to-south linkages from the international border
with Mexico via 1-19 from Nogales to Tucson, and 1-10 from Tucson to Phoenix, in Arizona;
and 1-15 in Nevada, Utah, Idaho, and Montana to the Canadian border. U.S. 93 provides a
north-to-south link between 1-10 near Phoenix to 1-15 in the Las Vegas metropolitan area.
Much of U.S. 93 is a two-lane undivided highway.
Currently, the Nogales border crossing handles more than 250,000 truck crossings annually
and is the primary point of entry for produce shipped by truck into the U.S. from Mexico
(ADOT, 1993). The U.S. 93 corridor has been recommended by ADOT to become Arizona's
link in the international trade route proposed by NAFTA.

ADOT plans to improve U.S. 93 to a four-lane divided facility from Wickenburg to north of
Kingman, Arizona in the next several years. In Nevada, U.S. 93 is four lanes from
Las Vegas to Boulder City. After implementing ADOT improvements, the only section of
U.S. 93 that will remain two lanes (between Phoenix and Las Vegas) will be the 19-mile
segment that includes Hoover Dam. Although most of the corridor would generally consist
of a high-speed divided facility, the Hoover Dam segment creates a traffic bottleneck
between Nevada and Arizona, potentially interfering with interstate and international
commerce.

Hoover Dam is the only Colorado River crossing near Las Vegas. The next closest crossings
are at Davis Dam, 67 miles downstream, or at Laughlin, 70 miles downstream. Because
shorter travel times and distances reduce accident exposure and transit costs, the shorter
Hoover Dam crossing is preferred by the commercial trucking industry for travel in the Las
Vegas to Phoenix corridor.

Other routes that cross the Colorado River are U.S. 95 and SR163 in Nevada to Arizona
SR 68 (see Figure 2-1), which would add 23 miles to the trip from Kingman to Las Vegas.

3-112 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Another route from Kingman to Las Vegas, 1-40 to Needles, California, and then north on
U.S. 95 to Las Vegas, adds 70 miles to the trip (see Table 2-1).

As the shortest route, U.S. 93 across Hoover Dam would offer a time savings for through
traffic between Arizona and Nevada if the existing bottleneck is eliminated at the dam.
Traffic flow is generally at speeds near posted limits except at roadway approaches to
Hoover Dam. Average speeds recorded on the approaches to the dam and across the dam
crest were as low as 8 mph (Traffic Study: Colorado River Bridge, Reclamation, December
1991).
The Hoover Dam section of U.S. 93 has reached capacity during peak periods and cannot
provide additional capacity with the current roadway alignment. In 1991, average travel
speeds for the 2 miles of roadway on either side of Hoover Dam were 8 to 18 mph.
Table 3-20 presents 1997 AADT and LOS at Hoover Dam (see Traffic Analysis -
Appendix A).

Table 3-20
Average Annual Daily Traffic and Level of Service at Hoover Dam
Measurement 1997
AADT 11,500
LOS F

The LOS compares projected traffic with the theoretical capacity of a roadway segment.
LOS is designated A to F, with A representing unconstrained and free-flowing traffic, and F
representing unstable flow with near gridlock conditions. As shown in Table 3-20, traffic
congestion at Hoover Dam is nearing gridlock.
Bicyclists and Pedestrians. Bicycles currently have access to and across Hoover Dam on
U.S. 93. There are no bicycle lanes on U.S. 93, nor is the highway a designated bicycle route.
The NFS and NDOT are in the process of developing a bicycle/pedestrian trail from
Boulder City to Hoover Dam on the Railroad Grade just north of U.S. 93 (see Section 3.8,
Recreation Resources).

3.9.2 Environmental Consequences

3.9.2.1 Build Alternatives
Population. No change in regional (Clark and Mohave counties) population is expected
from implementation of any of the build alternatives. Recent trends in population growth
are not expected to be altered. Because Boulder City has a growth ordinance, population
increases within the city are expected to continue at the same rate as in the past 10 years.
Employment. Construction of any of the build alternatives would create both direct and
indirect employment opportunities in the region. Direct employment would be provided
for project construction workers. Indirect employment would be provided for those in
construction material manufacturing and delivery, project goods and services, and project
operation and maintenance.
The number of direct and indirect jobs that would be created during the construction period
is based on the relationship between construction costs and the multipliers for construction
employment. It is expected that Las Vegas, Henderson, Boulder City, and Kingman would
provide the labor pool. During the construction period, between 2,900 to 3,440 new jobs
would be created in the region.

SCO/CHAP3.WPD/003672775 3'113
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

The Hacienda Hotel, located about 3 miles west of Hoover Dam, employs about 450 people,
many of whom live in Boulder City. Implementation of the build alternatives is not
expected to affect the number of employees at this establishment.

Income. Few permanent jobs would be created by construction of any of the build
alternatives; therefore, the personal per capita income is not expected to change in Clark or
Mohave counties.

In both Arizona and Nevada, minor adverse impacts may occur to the dam concessionaires
as a result of through-traffic reduction over the dam. However, these impacts would be
offset by the expected continued increase in dam visitors. Reduced traffic congestion on the
dam would make it a more desirable attraction to visit. The rafting concession would
continue operation with only minor interruptions by coordinating its scheduled raft
launching to avoid conflicts with construction activities; therefore, it is not expected to be
adversely affected. Access restrictions to Hoover Dam from Lake Mead would be
coordinated with lake tour operators.

Impacts to the local economy would be most notable during the construction period. Based
on the cost range for the alternatives, for every dollar spent in bridge construction and
highway approaches, $1.75 would be generated in the regional economy. An estimated
range of economic activity from construction expenditures would be from $233 to
$257 million.

During operation of the proposed project, traffic would continue to pass through Boulder
City as it currently does. Therefore, changes in spending within the city (and resultant
economic impacts) are expected to be negligible when compared to existing levels.

Social Conditions. Because the proposed project's western terminus is located about 4 miles
east of the Boulder City limits, the city's existing social infrastructure (including schools,
recreational areas, churches, businesses, and emergency services) is not expected to be
adversely affected. In fact, the reduction in traffic congestion and potential safety hazards
at and near the dam are likely to reduce the demand upon Boulder City emergency
response personnel. In addition, no businesses or households would need to be relocated,
and Boulder City's community cohesion and property values would not be affected.

If the proposed project is implemented, perceived social impacts, such as noise, pollution,
and associated decreases in quality of life, would occur in Boulder City at the current same
rate. Therefore, no impact on the city's social conditions is expected from any of the build
alternatives.

Environmental Justice. E.0.12898 requires identification and avoidance of
disproportionately high and adverse human health or environmental effects on minority
and low-income populations.

Because the area where the build alternatives would be constructed and operated is
currently unpopulated, no minority or low-income groups live in that area. Therefore,
disproportionately high and adverse human health or environmental effects on minority
and low-income groups are not anticipated.

Transportation and Circulation. U.S. 93 traffic forecasts were completed using historic traffic
data obtained from ADOT and NDOT and applying expected annual traffic growth rates of
between 4 and 5 percent for 1997. The AADT volumes and associated LOS at Hoover Dam
for years 2017 and 2027 under the No Build Alternative are presented in Table 3-21.

3-114 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
Table 3-21
Forecasted Average Annual Daily Traffic and Level of Service at Hoover Dam
Under No Build Alternative
Year

Measurement 2017 2027
AADT 21,100 26,000
LOS F F

Source: Appendix A, Traffic Analysis

The LOS at Hoover Dam is expected.to improve from F to E with implementation of any of
the build alternatives. The primary reason the LOS would not improve more than level E is
the mountainous terrain, steep grades, and sharp curves. Speeds are expected to be low;
however, the roadway capacity would be well above the anticipated demand, and traffic
delays on the dam are not expected.

If any of the build alternatives are implemented, the AADT and associated LOS in year 2017
for the new bridge crossing are 16,400 and A, respectively. In year 2027, the AADT and
LOS would be 19,900 and B, respectively.

Bicyclists and Pedestrians. Bicycles and pedestrians would be restricted from crossing the
new Hoover Dam bypass bridge if any of the proposed build alternatives are constructed.
The bicycle through route and dam access would be via existing U.S. 93, but some portions
would be impacted by the new highway and would need to be reconstructed. The dam
crossing would stay open to automobile traffic and bicyclists visiting the historic landmark.
The Nevada and Arizona connections of the old highway/dam crossing to the new U.S. 93
bypass roadway would be designed to provide ingress/egress for bicycles. Detailed traffic
analysis would be completed during final design to determine whether at-grade crossings
or interchanges are required to accommodate the expected volumes of vehicles exiting to or
returning from the dam crossing.

3.9.2.2 No Build Alternative
Implementation of the No Build Alternative would result in no change to existing
population trends and growth in Clark and Mohave counties. In addition, this alternative
would result in the creation of no direct or indirect jobs (and, therefore, no change to the
local economy), and no change to the existing personal per capita income level in the
region.
Similar to that for the build alternatives, no impacts to the existing social infrastructure of
Boulder City (including schools, recreational areas, churches, and businesses) are expected.
However, the expected increase in traffic congestion and associated potential safety hazards
at and near the dam may affect the demand upon Boulder City emergency response
personnel during emergencies. No businesses or households would need to be relocated,
and Boulder City's community cohesion and property values would not be affected by this
alternative.

If the No Build Alternative is implemented, perceived social impacts (such as noise,
pollution, and associated decreases in quality of life) would occur in Boulder City at the
current rate. Because the No Build Alternative would result in no project being constructed,
no adverse effects on minority or low-income populations are expected.

SCO/CHAP3.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

With implementation of the No Build Alternative, LOS is expected to remain F at Hoover
Dam. The AADT and associated LOS in year 2017 at the dam if the No Build Alternative is
implemented are 21,100 and F, respectively. In year 2027, the AADT and LOS would be
26,000 and F, respectively. Although LOS at the dam would continue to be F when
compared to existing conditions, the increase in AADT (83.5 and 126 percent in years 2017
and 2027, respectively) would result in significant transportation and circulation impacts on
U.S. 93 at and near the dam (see Table 3-21).

3.9.3 Measures to Minimize Harm

Because no adverse impacts on population, employment, income, social conditions,
minority or low-income populations, or transportation and circulation are expected as a
result of implementing any of the build alternatives, no mitigation is required.

3.10 Hazardous Materials

3.10.1 Affected Environment

Sites with known or suspected hazardous waste that may be affected by the proposed
project were evaluated to assess environmental concerns at each site. These sites are known
or suspected to be contaminated with hazardous wastes because of historical use, storage,
or release of hazardous materials at the site. This evaluation is based on Level I
Contaminant Surveys that were conducted for the Promontory Point, Sugarloaf Mountain,
and Gold Strike Canyon Alternatives in May 1992 (Reclamation, May 1992a, b, c), a
Resource Conservation and Recovery Act of 1976 (RCRA) Compliance Evaluation
Inspection report from March 1996, and a subsequent survey in May 1998. General
locations of these sites are shown in Figure 3-13.

3.10.1.1 Promontory Point Alternative
Seven potential hazardous waste sites exist on or adjacent to the Promontory Point
Alternative corridor: the Reclamation warehouse storage yard; two staging areas used by
contractors during construction of the new visitor center; two disposal areas used during
construction of the new visitor center and during rehabilitation of U.S. 93 in the vicinity of
the dam; a dump pile; and an abandoned switchyard. Because the Promontory Point and
Sugarloaf Mountain Alternatives both impact the Reclamation warehouse storage yard,
environmental concerns for this site would be the same as those discussed below, under the
preferred alternative.

Contractor Staging and Disposal Areas. At the time of the survey, Reclamation was building
the new visitors' facility at Hoover Dam. The prime contractor constructed two staging
areas for this work at Stations 120+00 and 125+00. The two disposal areas consisted
primarily of excavated rock, soil, and milled pavement; however, some old pipe, rebar,
scrap metal, and other construction debris were evident. One of the disposal areas had
been flattened and used for equipment storage. A large storage tank and several 55-gallon
containers of motor oil and antifreeze were also stored at one staging area on or near the
alignment centerline at Station 125+00.

These areas are of concern because chemicals, including motor oil, antifreeze, and diesel
fuel, were used and stored at these sites. Several noticeable oil stains were observed on the
ground (Reclamation, 1992a). If it is determined that chemicals were released to the soil,
3-116 SCO/9820800. WPD/003672775
-------
LAKE MEAD NATIONAL
RECREATION AREA
ABANDONED |/DUMP
SWTTCHYARDv */
DISPOSAL AREA^^jf

DISPOSAL /
LAKE MEAD NATIONAL
RECREATION AREA
0 950 1300 FEET

SCM.E IS APPROXIMATE
LAKE MEAD NATIONAL
RECREATION AREA
LEGEND

— PROMONTORY POINT ALTERNATIVE

— SUQAHLOAF MOUNTAIN ALTERNATIVE
_ GOLD STRIKE CANYON ALTERNATIVE
_ THAU.

^^— U.S.93
fists*-** HOOVER DAM RESERVATION BOUNDARY
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-118 . SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

contaminated soil may be encountered during construction activities. Site cleanup was the
responsibility of the contractor after completion of the project.
Dump Pile. An original dump pile used during construction of Hoover Dam is located along
the Promontory Point Alternative alignment (Reclamation, May 1992a), approximately
400 feet left of centerline at Station 151+00. The area has the appearance of an industrial
waste site due to the scattered metal shavings, numerous rusted 5-gallon and 55-gallon
containers, concrete blocks, scrap metal, and sheet metal. Some ground discoloration was
observed. Because the dump pile is located upgradient from the proposed alignment, a
potential pathway for contamination exists from the dump to the subject alignment through
surface runoff or a subsurface plume of contamination.

Abandoned Switchyard. There were several substantial oil stains noticed at each of the
switchyards norm of US. 93 in the immediate vicinity of the Promontory Point alignment.
The switchyard near the centerline at Station 151+50 is currently out of service. A
transformer had a yellow tag on it to indicate it contained PCBs. Additional environmental
concerns at mis site include oil stains on the ground. If the oil is the result of a transformer
leak, the oil could potentially contain PCBs.

PCBs are a subset of the synthetic organic chemicals known as chlorinated hydrocarbons.
Between 1926 and 1977, PCB-containing products were manufactured for use in
applications such as electrical transformers, where stable, fire-resistant, heat-transfer
properties were demanded. The most extensive use of PCBs occurred in dielectric fluids.
Such fluids typically have the following characteristics: a heavy oil appearance, high boiling
point, high chemical stability, high flash point, low electrical conductivity, and low water
solubility. PCBs are known to cause chronic reproductive effects, gastric disorders, and
skin lesions in laboratory animals. In addition, the U.S. EPA suspects that PCBs are
probable human carcinogens.
During the 1970s, in an effort to minimize the potential for adverse health effects caused by
PCBs and other substances, Congress passed the Toxic Substances Control Act (TSCA),
which strictly regulates all aspects of PCB use. TSCA prohibits the manufacture,
processing, and distributing in commerce of PCBs, except as exempted by the EPA. TSCA
also prescribes that the use, marking, and disposal of PCBs be strictly regulated by EPA.
Regulations issued pursuant to TSCA require generator identification numbers and the
manifesting of PCB wastes. Also, some state RCRA programs, particularly in the area of
disposal, place additional restrictions on the handling of PCBs.

In July 1992, the Tennessee Valley Authority (TVA), under a Western Area Power
Administration (WAPA) contract (Contract No. DE-A165-91WA 09429), conducted a
preliminary environmental assessment of the potential for PCB contamination of this and
other Nevada Power Company switchyards at this location. The report of this assessment,
which included sampling and analysis of transformer oils, noted that approximately
6,600 gallons of oil containing PCBs were present onsite in seven circuit breakers, ranging in
capacity from 600 to 2,200 gallons. Blue PCB labels on these circuit breakers indicated that
PCBs were present in the oil at concentrations under 50 ppm. An exception was one circuit
breaker bushing that had a yellow label, indicating PCB concentrations greater than
50 ppm. The Hazardous Material Coordinator for Hoover Dam has indicated that these
units have not been drained, and that jurisdiction and responsibility for proper closure of
the transformers/circuit breakers would lie with WAPA (personal communication, Jeff
Weaver, 1998).

SCO/CHAP3.WPD/003672775 3-119
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES. AND MEASURES TO MINIMIZE HARM

The TVA preliminary assessment also noted that one minor spill involving PCB-containing
oil occurred in 1990 at this location. The spill was remediated under the supervision of the
Phoenix office of WAPA. The assessment further evaluated the potential for PCBs at this
location to migrate into the environment. It was determined that the greatest threat to the
environment would come from storm-induced drainage through the site's lower
switchyards and culverts to the river. The potential hazards to the public and worker
exposures via the soil and air pathways was judged to be minimal (personal
communication, Jeff Weaver, 1998).

| 3.10.1.2 Sugarloaf Mountain Alternative (Preferred Alternative)
Six potential hazardous waste sites exist on or adjacent to the Sugarloaf Mountain
Alternative corridor: the Reclamation warehouse storage yard; two staging areas used by
contractors during construction of the new visitor center; one disposal area used during
construction of me new visitor center and during rehabilitation of U.S. 93 in the vicinity of
the dam; an active switchyard; and sewage evaporation ponds. Because the Sugarloaf
Mountain and Promontory Point Alternatives both impact the two contractor staging areas,
and one of the contractor disposal areas, environmental concerns are the same as those
discussed previously. The following sections address environmental concerns regarding
the Reclamation warehouse storage yard, the active switchyard, and the sewage
evaporation ponds.

Reclamation Warehouse Storage Yard. The Sugarloaf Mountain Alternative would pass
through the Reclamation warehouse storage yard at Station 107+00. Environmental
concerns at this site include past and present chemical use and storage, stained soils, and
drains and other pathways for potential contamination. A partial list of known chemical
and hazardous waste include paint, PCBs, solvents, used oil, asbestos, and solvent rags. A
small oil stain was noticed in the outside parking area of the warehouse.

Another concern at this site is potential residual petroleum hydrocarbons in soil resulting
from two leaking underground fuel storage tanks that were removed in 1991. The
underground storage tanks (USTs) were used for refueling maintenance vehicles and
consisted of a 500-gallon diesel fuel tank and a 3,000-gallon gasoline tank. An estimated
500 gallons of unleaded fuel were released to the soil. The site was subsequently
remediated in accordance with Nevada Division of Environmental Protection regulations
and to the satisfaction of the Clark County Health District.

A1996 inspection report states that the majority of hazardous waste currently generated
onsite is paint waste. Samples taken of sandblast residue were analyzed, and results show
that one sample contained 6 ppm lead, and all others passed toxicity characteristic leaching
procedure (TCLP) tests. The drum of material from which the "hot" sample was collected
was disposed of as hazardous waste. At the time that the samples were taken, staff
recommended that sandblast residues generated in the future be collected as they are
generated. The inspection concluded with no violations being observed at the warehouse
and storage yard facilities.

Arizona and Nevada Switchyard. This active switchyard is located downgradient of the
Sugarloaf Mountain Alternative near Station 139+00. The 1992 Level I Survey and
Contaminant Survey Checklist stated that there were several substantial oil stains noticed
on the ground at this site; however, WAPA staff have stated that the circuit breakers no
longer use oil containing PCBs.
3-120 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Sewage Evaporation Ponds. Two sewage evaporation ponds are located along the alignment
near the centerline at Station 183+00. These ponds receive sewage from the visitor center.
No evidence exists to suggest that industrial wastewater has been discharged to the ponds.
During 1992 and on other occasions, bighorn sheep have been observed grazing alongside
and drinking from the ponds, which removes most concern of contamination other than the
normal sewage that would be found at this type of facility. The two sewage evaporation
ponds will need to be excavated, closed, and relocated if the Sugarloaf Mountain
Alternative is implemented.

3.10.1.3 Gold Strike Canyon Alternative
One hazardous waste site, a spoil pile located in Nevada near the Colorado River, would be
impacted by the Gold Strike Canyon Alternative. The spoil pile is littered with metal
shavings, numerous 5-gallon and 55-gallon containers, concrete pillars, scrap metal, wood
timbers, and roofing material (that may contain asbestos). The spoil site is used as a
practice range for trie police personnel working at the dam. Surface soils at this waste site
could potentially be contaminated from historical chemical releases. Because the spoil site
is located downgradient of this proposed alignment, roadway runoff could potentially carry
and spread surface soil contamination further downgradient of the waste site.

3.10.2 Environmental Consequences

Discussion of potential impacts from hazardous material haul-vehicle accidents is provided
in the Water Resources section (Section 3.4).

3.10.2.1 Promontory Point Alternative
Because the Promontory Point and Sugarloaf Mountain Alternatives both impact the
Reclamation warehouse storage yard, measures to address environmental concerns at this
site would be the same as those discussed below under the Preferred alternative.

Contractor Staging and Disposal Areas. According to the Level I Contaminant Survey
(Reclamation, May 1992a), contractors were responsible for cleaning staging areas.
However, there is still the potential for encountering hazardous materials at the contractor
staging and disposal areas. If this material is discovered during construction, the contractor
would comply with the provisions of the Hazardous Materials Management Plan. During
construction operations, some of the material in the two disposal areas may be excavated
and either recompacted or moved to another location. Prior to excavation, additional
sampling and testing would be required to confirm that no hazardous materials were
disposed of at these sites.
If hazardous materials are discovered during surveys or construction, FHWA or its
contractor would become a hazardous waste generator. A generator identification number
would need to be obtained in order to transport hazardous materials, identify the
hazardous material, and disclose the haul route to a specific treatment and/or disposal
facility. The contractor must also comply with all requirements of the RCRA, associated
state hazardous waste disposal requirements, and all of the provisions of the OSHA
regulations regarding health and safety of workers and the handling of hazardous waste.

Dump Pile. To determine whether contamination from the dump pile has affected the
alternative alignment, soil sampling should be conducted. Subsurface soil samples will
determine whether a plume of subsurface contamination has migrated from the dump pile

SCO/CHAP3.WPD/003672775 3-121
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

to the alternative alignment. In addition, surface soil samples should be conducted to
determine whether surface runoff has carried contaminants to the alternative roadway site.

As described above for the Contractor Staging and Disposal Areas, the contractor would
comply with the provisions of the Hazardous Materials Management Plan if hazardous
materials were discovered during construction. Additionally, the contractor would be
required to comply with all requirements of the RCRA and associated state hazardous
waste disposal requirements, and all of the provisions of the OSHA regulations regarding
health and safety of workers and the handling of hazardous waste.
A generator identification number would also need to be obtained for the removal of any
hazardous materials from the dump pile, if any should be found. And, as described above,
FHWA or its contractor would need to disclose the haul route to a specific treatment and/or
disposal facility.

Abandoned Switchyard. To address environmental concerns at this site, surface soil samples
should be conducted before construction begins to determine whether oil or PCBs are
present. Construction workers could be exposed to hazardous materials if any PCB-
contaminated soil were present during construction or excavation in the project area.
If PCB-contaminated soils are unearthed or removed from the site, FHWA or its contractor
may become a hazardous waste generator. A generator identification number would need
to be obtained, as discussed above. The contractor would also be required to comply with
RCRA, associated state hazardous waste disposal requirements, and OSHA regulations.

3.10.2.2 Sugarloaf Mountain Alternative (Preferred Alternative)
Because the Sugarloaf Mountain and Promontory Point Alternatives both impact the two
contractor staging areas and one of the contractor disposal areas, measures to address
environmental concerns at these sites are the same as those discussed above. The following
sections describe measures to address environmental concerns at the Reclamation
warehouse storage yard, the active switchyard, and the sewage evaporation ponds.
Reclamation Warehouse Storage Yard. Contaminated soil may be encountered during
excavation and construction activities, and contaminated soils may pose health and safety
risks to construction workers. If encountered, this soil would require special handling,
storage, and disposal procedures according to the type and extent of contamination. If this
material is discovered during construction, rather than prior to, the contractor would
comply with the provisions of the Hazardous Materials Management Plan. In either case,
the contractor would be required to comply with all requirements of the RCRA and
associated state hazardous waste disposal requirements, and all of the provisions of the
OSHA regulations regarding health and safety of workers and the handling of hazardous
waste.
Further studies and soil sampling would be required to determine the type and extent of
contamination because there is no existing information regarding the potential hazardous
waste sites. After these studies are complete, FHWA, in consultation with the appropriate
regulatory agencies, would determine which soils can be handled as hazardous waste and
which soils would be handled as nonhazardous. When this information is available,
methods for treating the contamination onsite would be determined, and procedures for
handling and disposing of the waste would be resolved.
If it is determined that chemicals used and stored at the warehouse were released to the
environment, or that residual petroleum hydrocarbons are present, FHWA or its contractor
would become a hazardous waste generator upon extraction of the contaminated soil. The

3-122 SCO/9820800. WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

contractor would then need to obtain a generator identification number in order to
transport hazardous materials, identify the hazardous material, and disclose the haul route
to a specific treatment and/or disposal facility.

Arizona and Nevada Switchyard. The presence of soil staining at the switchyard indicates the
possibility of PCB-contaminated soil. Because PCB-contaminated soil requires special
cleanup and disposal procedures and may pose health and safety risks to construction
workers, soil samples would be taken in areas where oil stains are observed or leaks
suspected. If PCB-contaminated soils are unearthed or removed from the site, FHWA or its
contractor would become a hazardous waste generator. A generator identification number
would need to be obtained, as discussed above. The contractor would also be required to
comply with RCRA, associated state hazardous waste disposal requirements, and OSHA
regulations.
Sewage Evaporation Ponds. The proposed Sugarloaf Mountain Alternative centerline would
bisect the sewage evaporation ponds. While it is expected that no industrial wastewater has
been discharged to the ponds, this would be verified through sludge and soil sampling. In
either case, the two sewage evaporation ponds would need to be excavated, closed, and
relocated if the Sugarloaf Mountain Alternative is implemented.
If industrial wastewater were discovered in the pond, contaminated sludge or soils could
impact worker health and safety, as well as soil and sludge storage and disposal
procedures. The removal of these contaminated sludge or soils would result in FHWA or
its contractor becoming a hazardous waste generator. A generator identification number
would need to be obtained, as discussed above. The contractor would also be required to
comply with RCRA, associated state hazardous waste disposal requirements, and OSHA
regulations.

3.10.2.3 Gold Strike Canyon Alternative
Because the Nevada Spoil Pile is located downgradient of the proposed alternative,
roadway runoff could potentially affect this waste site. Roadway runoff should be
controlled through barriers or diverted to prevent future runoff from spreading potential
surface soil contamination downgradient of the waste site.

3.10.2.4 No Build Alternative
Should the No Build Alternative be selected, hazardous materials sites described above
would not be affected. No further testing or remediation would occur.

3.10.3 Measures to Minimize Harm

3.10.3.1 Promontory Point Alternative
Because the Promontory Point and Sugarloaf Mountain Alternatives both impact the
Reclamation warehouse storage yard, measures to address environmental concerns at this
site would be the same as those discussed below under the Preferred alternative.

Potential Contractor Staging and Disposal Areas. Documentation reviews and personnel
interviews would be conducted to determine whether releases have occurred, the extent of
contamination, and how the contamination was addressed. An assessment would be
conducted at the site to ensure that cleanup was conducted properly. Soil sampling would
be conducted if evidence (e.g., discolored soil, odors* stressed vegetation) suggests that
contamination may still be present.

SCO/CHAP3.WPD/003672775 3-123
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Dump Pile. If recommended sampling shows that contamination has migrated to the
proposed project location, excavation or remediation of affected soils may be required,
depending on contaminant types and concentrations. At a minimum, soil should be
monitored during excavation activities to segregate suspected contaminated soils.
Roadway runoff should be controlled by barrier use or by being diverted to prevent future
runoff from impacting the roadway site.

Abandoned Switchyard. If soil samples indicate that hazardous materials are present in the
area, affected soil should be removed and disposed of in accordance with applicable
environmental regulations. PCB-contaminated soil requires special cleanup and disposal
procedures and may pose health and safety risks to construction workers.

Any PCBs remaining in the transformers at the abandoned switchyard would require
proper disposal prior to demolition or dismantling. In addition, per EPA Region DC PCB
Spill Cleanup Policy, any PCB-contaminated soil would need to be remediated to
background levels (i.e., detection limits), where practicably attainable, for any PCB spill
from a source greater than 50 ppm PCBs. In certain cases, EPA Region IX would consider
alternative cleanup levels. Cleanup under the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) of 1980 allows deviation from the Regional
Policy when the reason for deviation is included in the Record of Decision (ROD).

3.10.3.2 Sugarloaf Mountain Alternative (Preferred Alternative)
Because the Sugarloaf Mountain and Promontory Point Alternatives both impact the two
contractor staging areas and one of the contractor disposal areas, measures to address
environmental concerns at these sites are the same as those discussed above. The following
sections describe measures to address environmental concerns at the Reclamation
warehouse storage yard, the active switchyard, and the sewage evaporation ponds.

Reclamation Warehouse Storage Yard. To address environmental concerns at this site,
chemical usage, storage, and releases would be investigated and documented. Interviews
of onsite personnel and internal record reviews would be performed to determine locations
and quantities of hazardous materials used and released in the storage yard. This
information would then be used to implement an investigation of soils that would be
affected by roadway construction. Soil samples would be taken in areas where
discoloration, odors, or known releases have occurred or are suspected. Soil would be
monitored during excavation activities to segregate contaminated soils.
Records documenting underground fuel tank removal would be reviewed to determine the
vertical and horizontal extent of contamination, location and quantity of contaminated soil
excavated, whether in situ remediation was implemented, and the cleanup standard
attained. This review would help determine whether residual petroleum hydrocarbons are
likely to be encountered during excavation and construction, and at what concentrations.
Soil in the tank area would be monitored during excavation to segregate contaminated soils.

Since contaminants could become airborne during removal, additional control measures
would be taken to ensure that airborne toxics concentration levels do not exceed any state
or federal standards.

Arizona and Nevada Switchyard. Surface soil sampling would be conducted in areas where
oil stains are located in order to confirm the presence of PCB-contaminated soil. If
PCB-contaminated soil is discovered in the switchyard and the site is affected by
construction of the bypass, affected soil would be removed and disposed of in accordance

3-124 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

with applicable environmental regulations. Alternately, if contaminated soils remain in
place, roadway runoff will be controlled by barrier use or by being diverted to prevent
future runoff from spreading the contamination downgradient of the yard. Per EPA
Region IX, PCB Spill Cleanup Policy, any PCB-contaminated soil would need to be
remediated to background levels (i.e., detection limits), where practicably attainable, for
any PCB spill from a source greater than 50 ppm PCBs. In certain cases, the EPA, Region
DC, would consider alternative cleanup levels. Cleanup under the CERCLA of 1980 allows
deviation from the Regional Policy when the reason for deviation is included in the ROD.

Sewage Evaporation Ponds. Soil and sludge sampling would be conducted to confirm that
industrial wastewater has not been discharged to the ponds. If it were discovered that
industrial wastewater had been discharged mere, contaminated sludge or soils would need
to be removed in order to protect workers' safety during construction of the proposed
project. Removal would require special safety and handling procedures and would require
compliance with all applicable state and federal regulations.
The ADEQ will be contacted before pond excavation during construction of the proposed
project to determine whether specific closure or material handling and disposal
requirements apply.

3.10.3.3 Gold Strike Canyon Alternative
Roadway runoff from the Nevada Spoil Pile should be controlled through barriers or
diverted to prevent future runoff from spreading potential surface soil contamination
downgradient of the waste site.

3.10.3.4 No Build Alternative
Should the No Build Alternative be selected, no mitigation is warranted because there
would be no effect.

3.11 Construction Activities and Impacts

This section presents activities and associated impacts that would occur during construction
of the build alternatives.

3.11.1 Construction Activities

Project construction activities would include the following:

• Earthwork (including clearing, grading, grubbing, embankment construction, batch
plant accommodation, fill, and erosion control activities)

• Removal or relocation of existing facilities

• Roadway approach construction (both Nevada and Arizona)

• Structure construction (bridges, tunnels, ramps, and walls)

• Roadway surfacing and barriers

• Existing traffic maintenance during construction

• Dust abatement

• Wildlife fencing, security fencing, and gates

SCO/CHAP3.WPD/003672775 3-125
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

• Cross-drainage culverts

• Signing and lighting

• Pavement marking and paint striping

• Landscaping and seeding

• Abandoned roadway obliteration

3.11.2 Construction Impacts

Construction impacts are short-term and temporary, and cease when a project is
operational. Project construction impacts include effects on local air quality and ambient
noise levels; increased erosion; potential fuels or chemical spills; potential transportation
and circulation impacts; effects on vegetation, wildlife habitat, recreation, and cultural
resources; disturbance of special-status species; and effects on the area's visual resources.
These impacts are discussed in more detail in this chapter.

Four separate construction contracts are expected for the proposed project the Nevada
approach, the Arizona approach, the bridge, and completion activities. Table 3-22 shows
estimated construction times for the Promontory Point, Sugarloaf Mountain, and Gold
Strike Canyon Alternatives. It is anticipated that Nevada and Arizona highway approach
construction would occur concurrently.

Bridge construction would not begin until significant portions of the approach highways
are completed. Paving would not begin until the bridge and both highway approaches are
completed.

Completion activities include paving the roadway and bridge, installing barriers and signs,
and finishing the tie-ins to the existing highway. Table 3-22 shows that these activities are
anticipated to require about 4 months, regardless of the alternative selected.

Table 3-22
Estimated Construction Period for Build Alternatives
Contract Promontory Point Sugarloaf Mountain Gold Strike Canyon
Nevada Approach 28 months 34 months 42 months
Arizona Approach 15 months 23 months 30 months
Bridge 38 months 36 months 33 months
Completion Activities 4 months 4 months 4 months
Total Construction Time 4 years, 9 months 4 years, 7 months 5 years, 3 months
Source: Reclamation. Colorado River Bridge—Hoover Dam, Arizona-Nevada. Phase B—Corridor
Studies. August 1992.

3.11.2.1 Promontory Point Alternative
This alternative would be located just south of existing U.S. 93 until it reaches the
Reclamation warehouse. Depending on the final design details, the new bypass roadway
will probably cross U.S. 93 at one location on a grade-separated structure and traverse the
Reclamation property east of the warehouse. Existing U.S. 93 would continue to provide
access to Hoover Dam, Lakeview Point, and the Reclamation warehouse (see Figure 2-4).

3-126 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Project construction would not affect traffic operations on the existing highway, except at
the beginning of the alternative where the two roads cross near the warehouse.

On the Nevada approach, it appears that a balance between cut and fill quantities can be
attained, and a waste disposal area would not be required. On the Arizona approach, one
waste disposal area would be required.

An electric transmission tower on the Nevada approach would need to be relocated.
Relocation of any one transmission tower may require additional work on adjoining towers
of that particular line. An abandoned WAPA switchyard would need to be removed.

No major detours, closures, or traffic delays are expected during construction of the
highway approaches. The existing highway could remain open with little interference
except during the tie-in activity at the beginning and end of the project. Completion of the
access road in Arizona is required before the existing highway could be closed to the public.
Hauling across the existing Arizona highway would be necessary. Some delays could occur
during blasting operations associated with excavation above the existing highway.

3.11.2.2 Sugarloaf Mountain Alternative (Preferred Alternative)
The preferred Sugarloaf Mountain Alternative follows the same corridor as the Promontory
Point Alternative except at the Reclamation warehouse area, where the alternative turns to
the southeast. Depending on the final design details, the new bypass roadway will
probably cross U.S. 93 at two locations on grade-separated structures and traverse the
Reclamation property east of the warehouse. Existing U.S. 93 would continue to provide
access to Hoover Dam, Lakeview Point, and the Reclamation warehouse (see Figure 2-4).

On the Nevada approach, it appears that a balance between cut and fill quantities can be
attained, and a waste disposal area will not be required. Hauling material for
embankments would be required. On the Arizona approach, all material excavated from
Sugarloaf Mountain would be expected to be used to build roadway embankments and no
disposal would be required.

The sewage evaporation ponds on the Arizona side would be removed, and new ponds
would be constructed downhill to the east of the existing ponds. The highway may affect
the Reclamation warehouse storage yards.

No major detours, closures, or traffic delays are expected to occur during highway approach
construction. The existing highway would remain open with little interference except
during the tie-in activity at the beginning and end of the project. Hauling across the
existing highway in two locations would be necessary. Construction of the Nevada access
road would accommodate existing highway traffic during construction.

Transmission Towers and Lines. Construction of the preferred alternative would require
removal and modification of existing electrical transmission components and construction
of new electrical transmission components. The final configuration of electrical towers,
transmission lines, and facilities would be determined during final design. FHWA would
work with WAPA during final design to select the most beneficial solution considering all
project elements and factors (e.g., operation and maintenance characteristics for both
electrical transmission and transportation, historic and visual impacts, and construction
considerations and costs). Any necessary modifications to the existing system would be
performed under the direct oversight of WAPA.
SCO/CHAP3.WPD/D03672775 3-127
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

Seven preliminary Colorado River crossing electrical transmission reconfiguration options
have been developed by WAPA in coordination with FHWA (see Figures 3-14A through
3-14G).

All options require removal of existing spans (up to 10) and towers (up to 4) and
construction of new spans (up to 7). Most options would require construction of new
towers (up to 4) and modification of existing towers (up to 2) and spans (1). All options
require removal of one or two existing Colorado River spans before bridge construction.
One option requires construction of a new Colorado River span. Three of the options
would require removal of the existing Arizona-Nevada Switchyard and replacing a
single-phase circuit with a double-phase circuit to the Mead Substation.
Regardless of the final electrical transmission configuration chosen at the Colorado River
crossing, the preferred alternative would require removal and construction of one tower,
modification of two existing towers, and removal and construction of two spans in the
vicinity of the bridge/tunnel on the Nevada side (see Figure 2-8).
Meetings with WAPA engineers confirmed that minimal additional right-of-way would be
needed to implement any of the options. Therefore, indirect impacts outside of the project
limits covered in this EIS would be minimal or nonexistent. FHWA would work with the
two SHPOs to mitigate any adverse effects related to removal of historic transmission
towers and facilities.

Construction Staging Areas. The preferred alternative is located generally south of the
existing road corridor so that construction can be accomplished without interfering with
traffic. Because the majority of the construction work would be done with no traffic to
maintain, most of the necessary contractor staging could be done within the proposed right-
of-way. For additional contractor staging, Reclamation has identified five areas that are
available (Figure 3-15). These areas have been previously disturbed and are presently used
for maintenance and contractor staging. No new staging areas would be required to
construct the preferred alternative.

Material Sources. The design of the preferred alternative would be advanced during final
engineering so that the earthwork quantities (cuts and fills) would be balanced. Borrow
material would not be required. A waste area for excess rock would not be required.

FHWA would not identify material sources for the production of aggregates. It is
anticipated that the native rock within the right-of-way may be adequate to produce some
or all of the aggregate needed for the project. Other aggregates may come from readily
available commercial sources in the Boulder City and Las Vegas vicinity.

3.11.2.3 Gold Strike Canyon Alternative
This alternative would begin about 1,000 feet east of the Hacienda Hotel. The alternative
would turn to follow Gold Strike Canyon toward the Colorado River.

Three waste disposal areas would be required on the Nevada approach to accommodate
excess waste material. One waste disposal area on the Arizona approach would be
required.
No significant relocation of existing features has been identified for this alternative. The
alternative would cross under several existing transmission lines; no existing transmission
towers would be affected. Two existing wood pole electric lines (one in Nevada and one in
Arizona) cross the alternative, and some minor pole relocation may be necessary.

3-128 SCO/9820800. WPD/003672775
-------
I !
'/J
,'tl r~ f'./'U •
1 , * :
LEGEND
Rstootod Trannninlon Lln.l

R»mov«d TrannnlMion Dim
FIGURE 3-14A
TRANSMISSION LINE REMOVAL

AND RELOCATION OPTION #1
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-130 SCO/9820800.WPD/003672775
-------
Mocatwl Tmwmlsslon Unn

RamovMl Tnmnntovlon Urns
SCOM2M3.16.05 fe»*ft«f3 (h 1100
FIGURE 3-14B
TRANSMISSION UNE REMOVAL
AND RELOCATION OPTION #2
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT

3-131
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-132 SCO/9820800. WPD/003672775
-------
r* \
" -Mil
't ' >,'

1 < ,H \ %
Rdoctlid Tran»ral««lon Llms

R«mov«l Tnmmiuion LlnM
* \
V% •>
^^% \"x^ . , *
4'/;r-

• iiPy !'\

FIGURE 3-14C
TRANSMISSION LINE REMOVAL

AND RELOCATION OPTION #3
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-134 SCO/9820800. WPD/003672775
-------
/ /-;;->'
/, -*
' / ' /? ' ''
' '//*//' •''
\f t f ' ' '
','',•''
LEGBfl)
RriotaMTimmiNlonLlMS
FIGURE M4D
TRANSWSSIONLJNEREMOVAi
AND RELOCATION OPTION 14
HOOVER DAM BYPASS PROJECT
ENVRONMENM IMPACT STATEMEKT

3-131
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-136 SCO/9820800.WPD/003672775
-------
4 • ;;, , a
>*? ,- -:>--
;, . ?^^x
/ * f* s
' P :'

R*aWTntwnlMiai Lines

Removal Tiwmwtai Lines
ToWead Substation
RGURE3-14E

TRANSMISSION LINE REMOVA1

AND RELOCATION OPTION 15
HOOe DAM BYPASS PROJECT

ENVIRONIBraL IMPACT STATEMENT

3-13
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-138 SCO/9820800.WPD/003672775
-------
- «.-*" , -"

' v»-^ *r /-** ' /•*"
,—-*^ ' - ' J.'5-ls
* /
ToHead Substation
(WocaWTwsmiMion Lines

I RMOwdTmniHioiiUKS
FIGURE 3-14F

TRANSiSSION LINE REMOVAL
AND RELOCAHON OPTION ISA
HOOVERMMBYPASS PROJECT
3-13
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-140 SCO/9820800.WPD/003672775
-------
f * x1*" ~

' > * f *? •a#''*"a

^ * -^ f
>> 1
-<.
* . -*"
' >C
*»* :''; .^-'.••'.,-;'
\\ ^r-,;-;-->
«* - ^:-'^-^f"
ToMeadSubstata
LEGEND
1 ReloaWTfwwwwLlies

I RmmdTnmMmLta
FIGURE J-14G

TRANSMISSION UNE REMOVAL

AND RELOCATION OPTION *6
HOtJ/ffi DAM BW\SS PROJECT
M41
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-142 SCO/9820800. WPD/003672775
-------
HACIENDA
HOTEL
END
PROJECT
1000 2000 FEET
LEGEND
—— PROMONTORY POINT ALTERNATIVE
• — EXISTING HIGHWAY U.S. 93
—. SUGARLOAF ALTERNATIVE
— — — GOLD STRIKE ALTERNATIVE
EXISTING CONSTRUCTION STAGING AREA
SCALE IS APPROXIMATE
SCO142883.15.05 promonlory2« Ih 11/00
FIGURE 3-15
POTENTIAL CONSTRUCTION
STAGING AREAS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
3-143
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM
This page intentionally left blank.
3-144 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

No major detours, closures, or traffic delays are expected during construction of the
highway approaches. The existing highway could remain open with little interference
except during the tie-in activity at the beginning and end of the project. Some
improvements to the existing Reclamation access road, including enlarging the old haul
road tunnel, would be required. All other Nevada construction access would be along the
alternative from the beginning of U.S. 93. The Gold Strike Canyon hiking trail would be
closed during construction, as the canyon bottom would be graded and used as an access
road. On the Arizona approach, construction access would be primarily along the
alternative from U.S. 93 back toward the river.

3.12 Energy

3.12.1 Construction Energy Usage

This section discusses the energy used to construct and operate the proposed project.
Construction and operation of the three build alternatives would require similar fuel
commitments. The No Build Alternative would not require fuel for construction.

The energy consumed to construct the proposed project can be estimated by making
assumptions about the following variables:

• Construction cost of the alternative
• Construction duration of the alternative
• Number of construction workers traveling to and from the construction site
• Number of trucks and pieces of equipment used
• Efficiency of trucks and equipment (e.g., mpg)
• Length of time trucks and equipment would be used

For this analysis, the energy consumed would be the fuel used for project trucks,
construction equipment, and workers' personal vehicles. Based on construction cost and
duration, the estimated number is 70 full-time-equivalent workers throughout the
construction duration of each of the build alternatives.

For the Promontory Point Alternative, fuel usage over the 4-year, 9-month construction
period is estimated at 500,000 to 800,000 gallons, or 400 to 640 gallons per day.

For the Sugarloaf Mountain Alternative, fuel usage over the 4-year, 7-month construction
period is estimated at 520,000 to 835,000 gallons, or 430 to 690 gallons per day.

For the Gold Strike Canyon Alternative, fuel usage over the 5-year, 3-month construction
period is estimated at 560,000 to 900,000 gallons, or 400 to 650 gallons per day.

3.12.2 Operation Energy Usage

Primary energy usage during operation of the proposed highway and bridge would be fuel
for vehicles traveling over the roadway and structure. Because roadway and bridge
inspection and maintenance would require regular, but infrequent, trips to the area, energy
usage for this phase would be lower than for the construction phase, and is not considered
significant.

Post-construction operational energy requirements are expected to be less per vehicle for
the three build alternatives than for the No Build Alternative because the existing traffic
congestion on U.S. 93 near Hoover Dam and atop the dam is expected to worsen as traffic

SCO/CHAP3.WPD/003672775 3'145
-------
CHAPTER 3 AFFECTED ENVIRONMENT, ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

volumes increase. This condition would result in increasingly lower fuel efficiency of
vehicles traveling across Hoover Dam.

3.13 Local Short-Term Uses Versus Long-Term Productivity

This section discusses the proposed project's short-term impacts on resource use, and
maintenance and enhancement of long-term productivity. Construction and operation of
any of the three build alternatives would result in similar short- and long-term impacts and
benefits. The following sections discuss these impacts and benefits.

3.13.1 Short-Term Uses of Man's Environment

Short-term project costs include the commitment of substantial financial and material
resources. Short-term uses of man's environment include project impacts considered
significant and temporary, including construction effects on local air quality; ambient noise
levels; increased erosion; potential fuel or chemical spills; potential transportation and
circulation impacts; effects on vegetation, wildlife habitat, recreation, and cultural
resources; disturbance of special-status species; and effects on the area's visual resources.
These impacts are mitigated to less man significant levels with the preferred alternative.

Project construction impacts are discussed in more detail earlier in this chapter. A benefit
during the construction phase would be the creation of construction-related employment.

3.13.2 Long-Term Effects of the Proposed Project

Dedication for the proposed project would preclude opportunities for alternate land uses.
Long-term effects of the proposed project include changes in landforms, visual quality,
recreational opportunities, and localized hydrology; an increase in localized ambient noise
levels; reduction of open space; and a loss of vegetation and wildlife habitat.

Long-term benefits would include increased public safety at Hoover Dam resulting from
traffic reduction and commercial truck elimination, and improved travel speeds on U.S. 93
resulting in time savings for personal vehicles and commercial trucking. An additional
benefit is U.S. 93 would become part of the international trade route proposed by NAFTA.

U.S. 93 on the Arizona and Nevada approaches to Hoover Dam currently operates at LOS E.
The LOS at the dam is currently F. If the No Build Alternative is implemented, both
approaches and Hoover Dam will be at LOS F by year 2017. Constructing and operating the
proposed project would result in LOS E at Hoover Dam, LOS B at the Nevada approach in
year 2017 and C for year 2027, and LOS A at the Arizona approach in year 2017 and B for
year 2027.

3.13.3 Conclusion

The proposed transportation improvements would meet long-term needs identified in the
Nevada and Arizona state transportation plans. These plans consider present and future
traffic requirements based on existing and future intended land use patterns. The local
short-term project construction impacts, after mitigation is implemented, are acceptable in
view of the maintenance and enhancement of long-term productivity that would be
provided for the local area; for Nevada, Arizona, and Utah; and for international trade
pursuant to NAFTA. In addition, long-term benefits provided by the proposed bridge and
roadway alternative are anticipated to outweigh the long-term impacts of operating the
facility.
3-146 SCO/9820800.WPD/003672775
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

3.14 Irreversible and Irretrievable Commitment of Resources

This section discusses the proposed project's irreversible and irretrievable commitment of
resources. Implementation of any of the build alternatives would require a commitment of
natural, physical, human, and fiscal resources. Construction and operation of any of the
three build alternatives would require a similar commitment of these resources. This
discussion focuses on the following issues:

• The project's use of nonrenewable resources during the construction and operation.
Included in this discussion are fossil fuels, highway construction materials, electricity,
water, and labor.

• The changes expected to occur as a result of the proposed project. These changes
include the commitment of land for the proposed project, physical changes in the
environment, effects on human populations, and fiscal changes.

3.14.1 Use of Nonrenewable Resources

As discussed in Section 3.12, construction of the proposed project would require the use of
fossil fuels for construction vehicles and equipment and construction worker vehicles.
Relatively minor amounts of electricity may also be used at construction trailers or by
portable generators during project construction. In addition, operation of the proposed
project would require the use of fossil fuels by vehicles traveling along the constructed
alternative.

Both labor and highway construction materials, such as concrete, sand, aggregate, and steel,
would be expended during construction. Labor and natural resources would also be used
in the fabrication of construction materials. These materials generally are not retrievable.
The use of these materials and labor during project construction would not have an adverse
effect on the continued availability of these resources. Operation of the proposed project
would result in greater fuel efficiency of vehicles traveling on the newly constructed
alternative when compared to those vehicles traveling at slower speeds on the existing
highway across Hoover Dam.

3.14.2 Expected Changes as a Result of the Proposed Project

Nevada and Arizona have committed land for use as a transportation corridor along
U.S. 93. The new Nevada and Arizona approaches would require the commitment of
additional land to construct and implement the proposed project. This additional
commitment of land would result in the loss of public parkland and recreation areas,
vegetation and wildlife habitat and foraging areas, and it would affect special-status species
and wildlife dispersion opportunities.

Land used for the proposed project is considered an irreversible commitment during the
period land is used for the highway facility. If, in the future, a greater need arises for use of
the land, or if the highway facility is no longer needed, the land could be converted to
another use. However, it is not likely that once the proposed project is constructed such a
conversion would ever be necessary or desirable.

As discussed in Section 3.7, Visual Resources, alteration of the landscape where the
proposed project is constructed would be considered an irreversible environmental change.
Although the proposed bridge and new highway could be removed and the land converted

SCO/CHAP3.WPD/003672775 3-147
-------
CHAPTER 3 AFFECTED ENVIRONMENT. ENVIRONMENTAL CONSEQUENCES, AND MEASURES TO MINIMIZE HARM

to another use in the future, it is neither likely that such conversion would occur, nor is it
likely that the landscape would return to its pre-project condition.

Construction of the proposed project would generate jobs for the approximately 4- to 5-year
construction period. During construction, labor would be needed to build the proposed
bridge and roadway and to fabricate construction materials. Long-term maintenance of the
proposed project would also generate jobs.

Construction of the proposed project would require a substantial one-time expenditure of
federal and possibly state funds, which are not considered retrievable. Long-term facility
maintenance costs are also not retrievable. A slight decrease in the amount of expenditures
at the two concession stands on the dam may result from fewer vehicles traveling across the
dam after the new roadway and bridge are constructed. No change in expenditures in
Phoenix or Kingman, Arizona, or Las Vegas, Boulder City, or Henderson, Nevada, are
expected from implementation of the proposed project. No change in highway taxes are
expected from the proposed project.

3.14.3 Conclusion

Tourists, residents, and the commercial trucking industry of Clark County, Mohave County,
and throughout Nevada, Arizona, and Utah would benefit by the proposed improvements
to the transportation system. These benefits consist of increased public safety at Hoover
Dam by reducing the amount of traffic on the dam and eliminating commercial trucks from
it; and improved travel speeds on U.S. 93, resulting in a time savings and reduction in
transit costs for commercial trucks and a time savings for personal vehicles traveling
between Phoenix and Las Vegas. In addition, roadway improvements would allow the
U.S. 93 corridor to be part of the international trade route proposed by NAFTA. These
benefits are anticipated to outweigh the commitment of the above-listed natural and fiscal
resources.
3-148 SCO/9820800.WPD/003672775
-------
CHAPTER 4
Unavoidable Adverse Impacts
4.1 Introduction

Some impacts to specific resources were evaluated for each build alternative and the No
Build Alternative, while others were evaluated regionally. Where data were available for
each alternative and effects differed, individual alternative analyses were performed.

Constructing and operating any build alternative would irreversibly and irretrievably
commit environmental resources to the project. An irreversible commitment is the
permanent loss of the resource.

4.2 Air

After implementing construction mitigation measures, no further adverse impacts were
identified. As a result of implementing one of the build alternatives, a beneficial impact
would occur because air quality is expected to improve in the proposed project area during
operations. Because of increased traffic, air quality in the Hoover Dam vicinity would
worsen if the No Build Alternative were selected (see Section 3.1). |

4.3 Noise

Even with mitigation measures, the Gold Strike Canyon Alternative would still exceed
standards at the upper end of the canyon on the hiking trail. Noise is higher for the No
Build Alternative than for any of the build alternatives at the dam crossing (see Section 3.2). |

4.4 Biological Resources

Implementing any build alternative could result in the loss of 122 to 143 acres of wildlife
habitat (see Table 3-13), including associated vegetation and either the displacement of, or
direct loss of, associated wildlife. Partial recovery of some of these losses may be attained
through the mitigation measures described in Chapter 3, Measures to Minimize Harm.
Implementation of the build alternatives will result in 0.66 to 2.77 acres of temporary fill
and 0.11 to 0.67 acres of permanent fill in waters of the United States (see Table 3-16,
Section 3.3). I

4.5 Water Resources

For the build alternatives, constructing the roadway will increase both short-term and long-
term sediment yield over existing conditions. Removing existing vegetative and rock cover
will disturb existing conditions, increasing the short-term sediment yield and impacting
local and, to a lesser extent, regional water quality. Using BMPs and other measures
discussed in Chapter 3 will reduce this impact.

For the three build alternatives, no adverse unavoidable long-term impacts would occur
following implementation of BMPs and design/construction of hazardous material spill
containment elements (see Section 3.4). |
SCO/CHAPT4.WPD/003672776 4-1
-------
CHAPTER 4 UNAVOIDABLE ADVERSE IMPACTS
4.6 Cultural Resources

4.6.1 Promontory Point Impacts

Adverse effects on the Hoover Dam National Historic Landmark (NHL) would occur from
visual elements of the project that would diminish the integrity of the historic features and
setting. Furthermore, FHWA and the NFS determined that construction of the new bridge
would adversely affect visitors' historic views of the dam from U.S. 93 in both Nevada and
Arizona, and this could not be mitigated. Based on the preliminary design, the Promontory
Point Alternative also would have an adverse effect on the following additional historic
properties eligible for the National Register for their association with the construction and
operation of Hoover Dam or as contributing elements to the NHL: NV:DD:14:30,
26-CK-4751,26-CK-4752,26-CK-4753,26-CK-4754,26-CK-4765, and 26-CK-5180 (see
Section 3.5).

Unavoidable adverse impacts would occur to prehistoric archaeological site NV:DD:14:23
and probably to site NV:DD:14:25. These impacts would occur during construction for the
former and operations for the latter. These sites were found to be ineligible for the National
Register.

The Promontory Point Alternative also would have an adverse effect on the Gold Strike
Canyon and Sugarloaf Mountain TCP.

| 4,6.2 Sugarloaf Mountain Impacts (Preferred Alternative)

Adverse effects on the NHL would occur from visual elements of the project that would
diminish the integrity of the historic features and setting. However, FHWA and the
Nevada and Arizona SHPOs determined these effects can be mitigated. Based on the
preliminary design, the Sugarloaf Mountain Alternative also would have an adverse effect
on the following additional historic properties eligible for the National Register for their
association with the construction and operation of Hoover Dam or as contributing elements
to the NHL: NV:DD:14:1, NV:DD:14:29, NV:DD:14:30,26-CK-4751,26-CK-5180,
26-CK-5789,26-CK-5790, and 26-CK-5792. Of these, sites NV:DD:14:1 and 26-CK-5790
would not be physically damaged but only indirectly affected by a change in the setting.

Unavoidable adverse impacts would occur to prehistoric archaeological sites NV:DD: 14:21
and NV:DD:14:22 from construction of this alternative. These sites were found to be
ineligible for the National Register; however, 14:21 is a contributing element of the TCP.

The Sugarloaf Mountain Alternative would also have an adverse effect on the Gold Strike
Canyon and Sugarloaf Mountain TCP; however, the alignment traverses the TCP in an area
of extensive disturbance. The Nevada and Arizona SHPOs, the Advisory Council on
Historic Preservation, and participating Native American tribes have signed a
Programmatic Agreement including measures and processes for minimizing harm to the
TCP from the preferred alternative.
4-2 SCO/CHAPT4.WPD/003672776
-------
CHAPTER 4 UNAVOIDABLE ADVERSE IMPACTS
4.6.3 Gold Strike Canyon Impacts

Based on the preliminary design, the Gold Strike Canyon Alternative would have an
adverse effect on the following historic properties eligible for the National Register for their
association with the construction and operation of Hoover Dam or as contributing elements
to the NHL: NV:DD:14:15, NV:DD:14:16, NV:DD:14:30,26-CK-4743, and 26-CK-4750.

Since no archaeological sites were identified along this alternative, no unavoidable adverse
impacts are expected.

The Gold Strike Canyon Alternative also would have an adverse effect on the Gold Strike
Canyon and Sugarloaf Mountain TCP. Based on the severity of this impact, it may be
immitigable.

4.7 Land Use

No unavoidable adverse impacts are identified for any of the three build alternatives. If the
No Build Alternative is selected, changes in land use would not occur (see Section 3.6). |

4.8 Visual Resources

The proposed bridge (regardless of the alternative implemented) would alter the view, both
during construction and operation, from Hoover Dam, Lake Mead, the river put-ins, or the
hiking trail and hot springs. For the Promontory Point Alternative, the impact on visual |
resources is considered unmitigable. Some viewers may consider the bridge to add variety
to the view.
FHWA and the NFS determined that construction of a bridge at the Promontory Point
crossing would adversely affect visitors' "first impression" historic views of the dam. These
views occur as motorists approach the dam on existing U.S. 93 from both Nevada and
Arizona. The dominance of the Promontory Point bridge would significantly detract from
the historic views of the dam and could not be mitigated. In contrast, the Sugarloaf
Mountain bridge would not detract from the historic views as visitors approach the dam
from the Arizona and Nevada approaches because it is not visible due to the existing
roadway alignment, which presents a direct view of the dam and Lake Mead (see
Section 3.7).

4.9 Recreation

Regardless of the alternative selected, construction activities would affect recreation
activities that occur in designated construction safety zones or construction areas. In
addition, the hiking trail in Gold Strike Canyon would be closed to public access during
construction of the Gold Strike Canyon Alternative. This effect is considered an
unavoidable adverse impact but is necessary to protect the public's safety.

The proposed bridge (if either the Promontory Point or Sugarloaf Mountain Alternative is
implemented) would alter the view, either from Hoover Dam, Lake Mead, or the river put-
ins. Implementation of the Gold Strike Canyon Alternative would alter the view from the
hiking trail and the hot springs. This impact is considered unavoidable but is not
necessarily adverse. Some recreationists are expected to consider the bridge as adding
variety to the views.

SCO/CHAPT4.WPD/003672776 4-3
-------
CHAPTER 4 UNAVOIDABLE ADVERSE IMPACTS
Unavoidable adverse noise impacts to recreation on the hiking trail are anticipated if the
| Gold Strike Canyon Alternative is implemented (see Section 3.8).

4.10 Socioeconomics

No unavoidable adverse impacts on population, employment, income, social conditions,
minority or low-income populations are expected from any of the build alternatives or from
the No Build Alternative.

Implementation of any of the build alternatives would have a beneficial impact on
transportation and circulation that would not occur if the No Build Alternative were
| selected (see Section 3.9).

4.11 Hazardous Materials

No unavoidable adverse impacts would occur from implementing any of the build
| alternatives or from the No Build Alternative (see Section 3.10).
4-4 SCO/CHAPT4.WPD/003672776
-------
CHAPTER 5
Cumulative Impacts
Note: The following chapter has been substantially revised based on comments received on
the DEIS from EPA (see Volume n).

5.1 Introduction

This section addresses potential cumulative impacts to the environment that could be
associated with the implementation of the proposed U.S. 93 Hoover Dam Bypass Project in
concert with one or more other past, present, or reasonably foreseeable future actions or
projects. Specifically, this section is prepared in accordance with the requirements of NEPA
and guidance from the Council on Environmental Quality (CEQ), Considering Cumulative
Effects Under the National Environmental Policy Act. The CEQ regulations define a
"cumulative impact" for purposes of NEPA as follows:

Cumulative impact is the impact on the environment that results from the
incremental impact of the action when added to other past, present, and
reasonably foreseeable future actions regardless of what agency (federal or
nonfederal) or person undertakes such other actions. Cumulative impacts
can result from individually minor, but collectively significant, actions taking
place over a period of time (40 CFR §1508.7).

This cumulative impacts section gives emphasis to the actions or projects that are likely to
cause the most significant cumulative impacts (i.e., projects that would occur relatively
close to the project site). For other transportation projects in the region, this cumulative
impacts section focuses primarily on the potential impacts of reasonably foreseeable future
actions. The impacts of past and present actions are also discussed, but in less detail and in
a more qualitative manner.

5.2 Cumulative Impacts Analysis

5.2.1 Other Actions/Projects Included in the Cumulative Impacts Analysis

The following criteria were considered in identifying those past, present, or reasonably
foreseeable projects that could result in cumulative impacts:

• Projects that have an application for construction and/or operation pending before an
agency with permit authority

• Projects that are listed on the Arizona Transportation Improvement Program (STIP) or
the Nevada STIP

• Projects that have the potential to generate environmental impacts that, when addressed
collectively with the proposed project, could result in cumulative impacts to the
environment

• Projects that are of a similar character, could affect similar environmental resources, or
are located in geographic proximity to the proposed project
SCO/CHAPT5.WPD/003672777 5-1
-------
CHAPTER 5 CUMULATIVE IMPACTS
5.2.2 Scope of the Cumulative Impacts Analysis

The geographic area addressed in this analysis varies according to the nature and
characteristics of each environmental resource. Two geographic areas are defined to
categorize this analysis. A description of each follows:

1. The first area is the vicinity of the proposed project and includes the area within the
NHL boundary, portions of the HDR boundary, and portions of the LMNRA (see
Figure 2-3).

2. A second area encompasses a substantial portion of the surrounding desert region, a
geographic area generally corresponding to the Las Vegas and Henderson urban area in
Clark County, Nevada, and Mohave County, Arizona. This geographic area is used to
include a broader range of other projects and environmental resources well beyond the
immediate vicinity of the proposed project.

5.2.3 Timing and Duration of Other Actions/Projects

For each of the projects addressed in this analysis, the time period in which it would be
implemented, including construction and operational phasing, is defined. Information on
the timing and duration for the other projects was obtained from applicant proposals, when
available. When this information was not available and could not otherwise be obtained
through reasonable efforts (e.g., direct contact with applicants), professional judgement was
used to estimate a reasonable time frame to complete the regulatory review and permit
issuance processes needed for implementation of the other projects.

5.2.4 Future Time Horizon of the Proposed Project

A horizon has been selected to discuss potential cumulative impacts of the Hoover Dam
Bypass and other past, present, and reasonably foreseeable projects. The time horizon for
the Sugarloaf Mountain Alternative, the preferred alternative, is 7 years, the approximate
time to complete design and construction.

5.2.5 Cumulative Projects Data and Information

Each of the projects addressed in this cumulative effects analysis is supported by different
levels of information, depending upon the current status of the particular project. For
future projects, this information ranges from a simple project description, identifying its
goals and objectives, to a comprehensive environmental review performed in accordance
with NEPA or other state or local environmental regulations. For past projects, relevant
agencies or departments were interviewed about documents that might discuss the history
of the project, including past project impacts.

This analysis uses the level of information available at the time this EIS document was
prepared to describe these other projects and their respective potential impacts on the
environment. If sufficient data or information on specific aspects of the proposed project
were not available to complete an analysis comparable to the evaluation of other projects,
and reasonable efforts to obtain that information were unsuccessful (as in the case of the
U.S. 95 widening in Nevada), professional judgement was used to estimate the potential
impacts.
5-2 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
5.2.6 Reasonable Forecast Analysis

In accordance with the CEQ guidance, this analysis assesses future cumulative effects for
projects that can be reasonably forecast. This includes those projects that are currently
funded or for which other NEPA analysis is being prepared, and those that are being
considered but have not reached a funding or environmental document stage.

5.3 Methods Used for Identifying Other Past, Present, and

Reasonably Foreseeable Actions/Projects

Several methods were used to identify other past, present, and reasonably foreseeable
projects that could, in concert with the proposed Hoover Dam Bypass, contribute to
cumulative impacts on the environment For projects occurring on lands administered by
federal agencies; the agency with primary land management authority identified projects
that could potentially contribute to cumulative environmental effects. These agencies
include the following:

ADEQ
ADOT
AGFD
FHWA
Los Angeles Department of Water and Power
NFS
Nevada Department of Conservation and Natural Resources
NDOT
WAPA
Reclamation
USFWS

Surveying other land management authorities within the southeast Nevada/western
Arizona region identified other projects. These surveys consisted of informal inquiries
designed to acquire existing available environmental documentation and project
descriptions. Concerning other projects located on private properties in the vicinity of the
proposed bypass, the Clark and Mohave County Planning Departments determined that
there are no applications or proposals for specific plans.

5.4 List of Past, Present, and Reasonably Foreseeable

Actions/Projects and Respective Environmental Impacts

The actions or projects that could result in changes to the local environment (and result in
cumulative impacts when combined with the proposed project) would include any actions
proposed by NFS and Reclamation, and highway projects proposed by NDOT, ADOT, or
local jurisdictions such as Clark and Mohave counties.

NPS and Reclamation administer the land in the immediate vicinity of Hoover Dam. No
new actions or projects are proposed within the project area by these two agencies;
therefore, no environmental impacts (such as biological, cultural, air quality, noise,
recreation, visual, or aesthetic) would result and, consequently, the proposed project would
not contribute to significant cumulative impacts. Similarly, no projects are proposed by

SCO/CHAPT5.WPD/003672777 5-3
-------
CHAPTER 5 CUMULATIVE IMPACTS
Clark and Mohave counties in the immediate project vicinity that would contribute to
cumulative environmental impacts with the proposed project.

ADOT and NDOT each have two reasonably foreseeable future projects. NDOT plans to
begin improvements (widening the two-lane segments to four-lane, median divided) to
U.S. 95 from the California/Nevada state line to the U.S. 93 intersection west of Boulder
City. Further, NDOT is currently preparing an environmental document for U.S. 93
improvements from the western terminus of the Hoover Dam Bypass project to U.S. 93
about 1 mile north of Railroad Pass Casino, west of Boulder City. ADOT is currently
constructing improvements on Arizona SR 68 from MP12 to MP 14.5. Further, ADOT
plans to begin a preliminary study for improvements to U.S. 93 from the LMNRA eastern
boundary to the eastern terminus of the Hoover Dam Bypass project.

5.4.1 Past Actions/Projects Near and Within the Project Vicinity

In its natural state, the Colorado River flowed unimpeded some 1,700 miles with a vertical
elevation drop of more than 14,000 feet from its beginnings in the southern Rocky
Mountains and eastern Great Basin to its terminus at the Gulf of California. The lower
portion of the river from the Grand Canyon downstream was typically low gradient and
flowed through a rather broad alluvial valley with relatively few confined reaches. At its
mouth was an alluvial delta containing vast marshes, riparian forests, and backwaters.
Such habitats were present along the entire reach of the lower river. The riparian belt
extended away from the river for up to several miles, where the water table was relatively
shallow.

Seasonal flooding resulted in the creation of several distinct communities of plants and
animals. High water occurred around June, with low flows occurring during the winter
months. Riparian communities were in a constant state of succession as the river, on a
seasonal basis, was constantly depositing new sediment, shifting its channel, and creating
and destroying habitat. Floodplain communities developed in areas prone to extended
periods of inundation, and the aquatic community evolved consisting of a main channel
with separate or connected oxbows and backwaters.

The overall ecosystem of the lower Colorado River today is quite different from that which
existed prior to modern day use and development. During historic times, the area
surrounding the Hoover Dam was used for a wide variety of purposes. Past activities in the
project area and vicinity included cattle grazing, hunting, and mining for turquoise, gold,
and silver. Mining occurred in the late 1800s and early 1900s in several areas within about
5 miles of Hoover Dam. Turquoise mining occurred near the location of the Hacienda
Hotel; gold and silver mining occurred in locations on the Arizona side of the dam. Cattle
grazing and hunting historically occurred in the project vicinity, but were not allowed near
Hoover Dam (personal communication, Bill Burke, NPS, 1998).

The project area and vicinity currently consist of a mixture of land uses and f acilities.
Current uses and facilities include the dam and related hydroelectric facilities, a utility
corridor (transmission towers and lines), a transportation corridor (U.S. 93 and access roads
to the dam, lake, and river), and developed recreation facilities (visitors' center and parking
garage at the dam, boating facilities, rafting and canoeing facilities, hiking trails, hot
springs, and scenic lookouts).
5-4 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
These past and present activities, in addition to future planned projects, have and will
continue to have a variety of impacts on the environment in the vicinity of Hoover Dam.
These projects are described below in chronological order from past to future.

5.4.1.1 Construction of Hoover Dam
In 1928, Congress passed the Boulder Canyon Project Act authorizing construction of
Hoover Dam. (Hoover Dam has also been called Boulder Dam; Congress made the name
Hoover Dam permanent in 1947 after Herbert Hoover, the 31st President of the United
States, who strongly supported construction of a high concrete dam on the Colorado River.)
Construction of Hoover Dam began in 1931, and the last concrete was poured in 1935 -
exactly 2 years, 1 month, and 28 days ahead of schedule. Hoover Dam's reservoir, Lake
Mead, is America's largest man-made reservoir and can store 28.5 million acre-feet
(9.2 trillion gallons) of water, or nearly 2 years of the river's average annual flow. (An
acre-foot of water could cover a football field to a depth of 1 foot.)

Direct Impacts of Dam Construction
In order to construct Hoover Dam, engineers first drove a diversion tunnel through the wall
of the river canyon from a point upstream of the dam site to a point downstream. They
then lined the tunnel with concrete and built inlet and outlet sections to minimize flow
turbulence. Cofferdams (watertight structures mat allow exposure of the riverbed) were
placed across the river above and below the dam site to divert the water into the tunnel and
prevent it from backing up into the dam site. During construction of Hoover Dam, the
Colorado River was diverted into four 56-foot-diameter tunnels averaging more than
4,000 feet in length. These tunnels were drilled and blasted out of the rock walls on either
side of the river. Tunneling activity reached its peak in January 1932, with as much as
16,000 cubic yards of rock being hauled away every day by the truck fleet. The construction
of the cofferdams required the removal of nearly 213,000 cubic yards of river silt from the
bed of the Colorado River, which was replaced by sand and gravel and covered with
concrete.
These activities completely altered streamside communities in the construction zone. The
river could no longer supply water to flora and fauna along the natural stream course, and
organisms that move with the stream flow had no natural bank habitat to supply them with
nutrition and cover. After they diverted the river, work crews cleared the vegetation from
the dam construction and reservoir areas. Thus, riparian habitat was directly destroyed.
Dam construction required excavation of foundation and abutment areas for the dam. First
workers dredged the area and removed all earth, sand, gravel, and loose rock, directly
destroying riparian vegetation. Digging in the river bottom may have lowered the water
table and made water inaccessible to established vegetation root systems. Additional rock
was drilled, blasted, excavated, loaded, and removed so that the dam could be constructed
on solid bedrock.
Facilities, such as roads, buildings, minor utility pipelines, surfaced areas for parking, and
storage areas, were developed to facilitate construction. For the Hoover Dam construction,
power lines were also strung across the Mojave Desert from San Bernardino and Victorville,
California, to a substation on a rocky promontory near the canyon rim to provide power for
all machines and illuminate the entire dam site, including tunnels.

As part of the necessary infrastructure for the construction of the dam, the Boulder Canyon
Project Federal Reservation was created. This 144-square-mile area in the Eldorado Valley
included the dam site, the lower portion of the future reservoir, the site of Boulder City, and
SCO/CHAPT5.WPD/003672777
5-5
-------
CHAPTER 5 CUMULATIVE IMPACTS
vast stretches of open territory around the town. This area was under federal control and,
unlike the surrounding jurisdictions, gambling, the sale of liquor, and other practices
deemed injurious to the workers and the orderly progress of work were strictly prohibited.
The town, named Boulder City, included eight 172-man dormitories, one 53-man office
dormitory, more than 600 family cottages, a mess hall and recreation hall, an office
building, company store, laundry, and a 20-bed hospital. Sewer and water lines were laid
out and hooked up, and nearly 20 miles of streets were paved. Reclamation spent well over
a million dollars constructing the administration building, government residences, and
landscaping for streets and parks. Privately financed structures housing various
independent businesses sprung up along Nevada Highway, the main street in town. The
key to mis transformation of the Eldorado Valley was a network of elaborate, expensive
pumps and pipes that carried water from the Colorado River out of Black Canyon to the
town (Stevens, 1988).

After the construction of Hoover Dam was completed, a large portion of Boulder City was
razed, as required by the government contract. This included hundreds of cottages, half a
dozen dormitories, the mess hall, the recreation hall, and many other structures. The
southern half of the city was returned to a state dosely resembling its predam condition.
Two dormitories were set aside to house Civilian Conservation Corps workers working on
the Boulder Dam National Recreation Area, and a number of cottages were resold and
hauled offsite for other uses. However, the landscaping remained and some of the original
buildings are still standing, including the hospital, Grace Community Church, the Boulder
Dam Hotel, and a number of enlarged and renovated cottages (Stevens, 1988).

On February 29,1936, Hoover Dam and its powerhouse were accepted as complete. In
addition to the direct, adverse, environmental effects of the dam's construction, there were
immediate beneficial effects, which included water and power for the Los Angeles
metropolitan area and water and flood protection for the fertile agricultural lands of
Southern California and Arizona.

In general, the development of Hoover Dam and its associated facilities involved
construction activities that likely resulted in temporary localized impacts on air quality,
ambient noise levels, water quality, recreation resources, and aesthetic and visual resources.
Impacts on local air quality would have likely occurred from construction equipment and
vehicles traveling on dirt roads and during earth-moving activities. The impacts from
increases in ambient noise levels would have resulted from the construction equipment,
vehicles, and personnel constructing the various projects. Impacts to local water quality
and riparian ecosystems could be expected to have occurred where construction activities,
including scaling of the cliffs in Black Canyon, were conducted near Lake Mead, the
Colorado River, or any of the washes or other water bodies in the project vicinity. The
impacts to aesthetic resources would have occurred from the presence of the construction
vehicles, equipment, and personnel, the dust and noise generated, and the change to the
landscape that resulted. All of these impacts are construction related, specific to the
projects' locations, and once the projects were completed, the impacts ceased and natural
systems (air, water, vegetation, and wildlife) adapted and stabilized. Furthermore, prior to
development of the dam, there were no permanent human receptors or habitations sensitive
to noise, air, and aesthetic impacts - only construction workers and visitors to the
construction site.

Long-term impacts to cultural resources occurred during project construction because of
both the disturbance to the cultural resource sites and the imposition of new facilities

5-6 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
changing the setting and accessibility of cultural resource sites. Consultations with Native
Americans for the DEIS provided numerous comments from tribal informants that
construction of the dam and impounding of the waters of Lake Mead had a serious adverse
effect on the traditional cultural landscape.

Substantial long-term visual effects on the environment occurred. After project
construction was completed and the construction vehicles and equipment were removed,
the change to the landscape from the dam and Lake Mead was dramatic and profound, and
it was unlikely to revert to its preproject conditions.

The development of Hoover Dam and its associated facilities also contributed in a beneficial
manner to the local and regional economy, local recreation resources, transportation and
circulation in the area, and public utilities across the southwestern United States. This
project, constructed during the Great Depression, employed a large number of previously
unemployed workers. This work and fee paycheck it provided enabled employees and
their families to move from the tents and shacks north of Las Vegas to Boulder City, and to
forego the soup kitchens in Las Vegas. Beneficial economic effects were realized regionally
during construction from the purchase of materials, goods, and services in the local area
and region. Construction personnel working on these projects contributed to secondary
spending by their individual purchases of goods and services. Additionally, some workers
made a large impact to the economy of Las Vegas by gambling away the majority of their
paychecks during their days off.
Benefits to recreationists occurred by the development of additional recreation facilities and
opportunities in the area. Benefits to commuters, tourists, commercial truck traffic, and
local and regional consumers accrued by the development of the local roadway and
interstate highway system in the area and the creation of HDNHL, a major tourist
attraction. The development of U.S. 93 provides a more direct route between Las Vegas and
Kingman, improving interstate commerce and numerous recreation facilities and other
types of establishments.

Loss of Riparian Vegetation. Filling the reservoir and operation of the dam severely impacts
vegetation, both in the immediate area around the dam and downstream. When the
reservoir fills, riparian habitat becomes inundated, directly destroying the submerged
vegetation. Many of the plant species that are not submerged in the initial filling area are
unable to tolerate the subsequent water-level fluctuations typical in reservoirs and die off,
reducing habitat for wildlife. Terrestrial habitat shrinks in acreage as a direct result of
inundation. The land-water interface in the project area increases, resulting in shifts in flora
and fauna as the ecology changes from that of a river to that of a lake-like impoundment.

Because sediment is entrapped in the reservoir upstream of a dam, the downstream system
receives essentially clear, "sediment-hungry" water. The clear water derives its equilibrium
load by entraining bed sediments and eroding riverbanks. These actions decrease the
floodplain width and, therefore, decrease the area available for establishment of riparian
habitat.

If the normal pattern of seasonal flooding is altered as a result of dam operation,
long-established patterns of soil fertility relationships will change as well. For example,
riparian vegetation that depends on spring deposition of silt for seedling establishment will
not be generated. Floodplain lakes, marshes, swamps, and ponds may not receive annual
of seasonal replenishment of water and nutrients. Use of a dam for hydroelectric

SCO/CHAPT5.WPD/003672777 5'7
-------
CHAPTER 5 CUMULATIVE IMPACTS
generation can produce fluctuations downstream that shift conditions from those of a large
stream to those of a small headwater in a short period of time.

Effect of Dams on Terrestrial Life. Many birds use the shores and banks of streams and rivers
for nesting. Although reservoirs can increase the area of land suitable for nests, dam
operation often causes unexpected fluctuations in water levels that wash away eggs or
inundate nest sites.

Other birds use riparian trees for nesting, roosting, and hunting. Reservoirs often make
open-water habitat out of streamside forests, killing the trees. The effect is beneficial for
snag-loving birds, so long as the dead trees are left standing, but it is detrimental for birds
that use living trees during their various life stages.

Reptiles and amphibians commonly lay their eggs on stream banks or in river shallows.
Reservoir fluctuations prematurely end their development, as the eggs are either inundated
or desiccated beyond their tolerance.

The development of Hoover Dam facilities resulted in long-term changes to biological
resources. Impacts to biological resources typically occurred during the construction phase
of a project, but they are considered long-term because of their effects on local habitats and
species. Although the dam was constructed prior to the Endangered Species Act,
substantial impacts likely occurred to both common and sensitive native plant and animal
species.

Effects Of Dams on Aquatic Life. Faunal remains in archaeological sites show that Colorado
River fishes were caught and eaten by Indians, as well as early canyon explorers. Studies
completed during the late 1930s, during and after the construction of Hoover Dam, noted
faunal declines when compared to earlier studies. A1944 survey of the lower Colorado
River was the first to provide insight on both native and introduced fishes downstream
from the new Hoover and Parker dams. Reductions in native species were attributed to
environmental changes associated with damming (Hunt and Huser, 1988).

Impacts have resulted from changes to wetland vegetation along the river. Streamside
vegetation is essential in maintaining the aquatic ecosystems that support fisheries. Roots
of riparian plants stabilize banks, prevent erosion, and occasionally create overhanging
banks that serve as cover for fish. Streamside trees and herbs decrease the amount of
sediment passing into the water and keep water temperatures cool enough to support
cold-water fisheries. Sedimentation blocks fish gill filaments and results in fish death by
anoxemia and carbon dioxide retention. Sedimentation also decreases the oxygen supply to
fish eggs, resulting in their death, and alters the habitat of the aquatic invertebrates mat
form the prey base for many fish.

Riparian vegetation also serves as a source of large organic debris, which distributes
sediments in a stream and creates pool and riffle habitat for aquatic organisms. Organic
debris is an important source of nutrition for aquatic ecosystems.

Alien fish also attracted early attention in research studies and surveys. Lake Mead
changed the Colorado River in ways that enhanced lentic-adapted (i.e., adapted to living in
still waters such as lakes, ponds, or swamps), non-native species, and reservoir sport
fisheries became important regional resources. A remarkable array of both native and
non-native species were used as bait, and bait and forage fishes escaped or were
intentionally stocked to join and feed expanding game fish populations. Many alien fish

5-8 SCCVCHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
could not adapt to the environment or competition for resources and disappeared, but
others became well established. The original fauna of 30 or so native species in the
Colorado basin has increased to 80 or more, including species from as far away as Europe,
Asia, and Africa. Few things seem to help native fish survive the presence of alien species,
aside from strong evidence that flooding in canyons displaces non-native fish, while native
species are unaffected. In fact, native fish are often enhanced by flood removal of predators
and competitors. However, the effect is temporary, since alien fish from populations
protected in reservoirs and ponds upstream soon reinvade the canyons (Hunt and Huser,
1988).

Establishment Of Salt Cedar. Historically, the lower Colorado River ecosystem was a mosaic
of different native vegetation communities comprised mainly of Fremont cottonwood,
Goodding willow, honey mesquite, screwbean mesquite, quailbush, and arrowweed, as
well as many other plant species. This ecosystem was extremely important to many wildlife
species, especially neotropical migratory bird species. However, native plant communities
began to change soon after me completion of Hoover Dam. The elimination of annual
spring floods produced an environment more suitable for the establishment of salt cedar, an
exotic plant introduced during the mid-1800s, than for the regeneration of many native
species.
While many native species are very susceptible to elimination by fire, salt cedar thrives on
it. Salt cedar drops its needles each year during the winter, producing a thick carpet of
highly flammable duff within a short amount of time. Once a fire begins, it spreads rapidly
through the salt cedar. After burning, salt cedar sprouts new shoots from roots, while many
native species do not. Salt cedar also produces seed throughout almost the entire year, so it
is ready to take advantage of any disturbance that occurs, including fire. Through these
two mechanisms, salt cedar is able to outcompete native plants and has become the
dominant plant species along many riparian areas in the Southwest, including the lower
Colorado River. Many areas have become pure stands of salt cedar after wildfires have
swept through. Unfortunately, salt cedar has limited value as wildlife habitat.
Additionally, as the predominance of salt cedar increases along the Colorado River, so does
the frequency of wildfires, thereby spreading salt cedar even more.

Potential Cumulative Impacts
The construction of Hoover Dam has resulted in long-term impacts to the immediate
vicinity and surrounding region. The U.S. 93 Hoover Dam Bypass Project will have
localized, long-term impacts to terrestrial wildlife, desert washes, and aesthetics of Black
Canyon; therefore, the bypass will contribute to cumulative impacts in the project area.
These impacts are discussed in more detail in Section 5.5.2.

May and June 1998 site visits and field interviews with Native American tribal elders,
conducted for FHWA by the University of Arizona, resulted in completion of an
ethnographic study report for the Hoover Dam Bypass project in December 1998. That
report included preliminary findings, summarized in the DEIS, indicating the presence of
potentially significant traditional cultural properties in the vicinity of the bypass project.
Additional site visits and interviews were conducted during May 2000. The resulting report
(FHWA, October 2000a), provided documentation supporting a determination by FHWA
and the SHPOs that the Gold Strike Canyon and Sugarloaf Mountain TCP is eligible for the
National Register of Historic Places. In the interviews with the tribal elders, there was a
clear feeling expressed that the construction of Hoover Dam had a substantial adverse
impact on traditional cultural values, including: inundating the Colorado River from which

SCO/CHAPT5.WPD/003672777 5'9
-------
CHAPTER 5 CUMULATIVE IMPACTS
traditional songs and power were derived; flooding Native American village sites, a salt
trail, and salt mines; destroying ancient fishing places; bringing pollution, public access,
and vandalism to traditional lands; impacting the land with numerous power transmission
towers; and overdeveloping the area for recreation. The Hoover Dam Bypass will have an
adverse effect on the TCP and is discussed in Section 5.5.1.

5.4.1.2 Hoover Dam Visitor Center and Parking Facilities
The new visitor center and parking garage was opened at Hoover Dam in 1997. The
Finding of No Significant Impact (FONSI) for the Visitor Center and Parking Facilities
(September 20,1979) concluded that there would be slight social and economic impacts.
Reclamation, in consultation with the Nevada and Arizona SHPOs, determined that the
project would have an adverse effect on the HDNHL. That effect was addressed through
design review stipulations in an MOA signed by the federal ACHP on April 9,1991.

Impacts on wildlife and vegetation were determined to be extremely small, almost
nonexistent, and only temporary in nature because they would cease at the end of
construction. Impacts to natural vegetation and archaeological sites that may have been
present in the project area were minimized or avoided because they were destroyed or
covered with concrete when the dam was initially constructed. The remaining natural
vegetation is located on the canyon walls, and very little of the project occurred in that
area.

The project was found to have beneficial effects by improving safety, relieving congestion,
and providing a more efficient means of operation, particularly of the visitor services.
Visitors would no longer have to wait for long periods in extreme heat and would be able to
take the tour in a much more enjoyable and efficient manner. The project was determined
to be in harmony with the designs, aesthetics, and the operation of the dam, and would
provide for a continuity of design and purpose. The project features were designed so that
they would blend with the existing dam and facilities.

Potential Cumulative Impacts
According to the FONSI, construction did not result in impacts that were more than
minimal. As a result, this project, in combination with the proposed Hoover Dam Bypass,
would not result in any cumulative impacts.

5.4.2 Present Actions/Projects Near and Within the Project Vicinity

This section focuses on federal, state, and local agency management plans and programs
affecting the environmental resources in the project area. Detailed references for these
plans and programs can be found in EIS Chapter 9.

5.4.2.1 Lake Mead General Management Plan
NPS's Lake Mead General Management Plan, approved in 1986 for a 25-year or longer
period, follows a strategy that centers on accommodating increasing visitor use while
protecting the area's most outstanding natural and cultural resources. It also addresses
visitor use and flash flood safety problems that face most developed areas.

Solving existing crowding/congestion problems and accommodating projected increases in
visitation would require expansion and improvement of existing developed areas,
circulation improvements, improvement of existing shoreline access points, and
establishment of new developed areas. The Management Plan establishes maximum levels

5-10 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
of development that could accommodate increasing use in the future, while not exceeding
reasonable capacity limits. These are maximum levels, not goals; development within the
maximum levels would occur only when demand and economic feasibility justify the
expansion (NFS, 1986).

The Management Plan has resulted in and will continue to result in the following primary
impacts during the 25-year projected life of the plan:

• Improvements in water quality in beach areas

• Destruction of or severe damage to soils, causing minor disruptions in drainage patterns
that would temporarily increase erosion potential

• Seismic exploration for oil and gas leases would have the potential to cause adverse
impacts to bighorn sheep herds, although proposed mitigation measures and the
assumption that activity would remain sporadic, as in the past, reduces these impacts to
a less man significant level

Potential Cumulative Impacts
Management Plan impacts, when considered in conjunction with those from the Hoover
Dam Bypass Project, may result in cumulative impacts to the bighorn sheep population.
The plan will result in beneficial impacts to water quality, so the bypass would not
contribute to cumulative water quality impacts. Similarly, the Hoover Dam Bypass Project
is not expected to impact soils, so cumulative soil impacts are not expected. Cumulative
impacts to the bighorn sheep population are discussed in more detail in Section 5.5.2.

5.4.2.2 Reclamation Endangered Species Conservation
As part of Reclamation's ongoing operations and maintenance activities, the agency has an
ongoing program of endangered species conservation. These programs are defined in the
Description and Assessment of Operations, Maintenance, and Sensitive Species of the
Lower Colorado River (Reclamation, 1996). The activities range from very specific to broad
multispecies conservation programs, and they occur within the immediate Hoover Dam
Bypass Project area as well as in the surrounding region. Reclamation's endangered species
conservation activities include the following programs.

Endangered Razorback Sucker and Bony tail Conservation. Reclamation has an active
program for the conservation and recovery of endangered razorback suckers and bonytail.
These activities are part of the current routine operation of the Lower Colorado River
system. As part of the Lower Colorado River Multi-Species Conservation Program (MSCP)
interim conservation effort, federal and state biologists met in July 1995 to prioritize and
quantify recovery and conservation program needs for endangered fish and other species
during the 1995 to 2005 period. The following programs represent some of the ways this is
currently being achieved.

• Native Fish Work Group. The purpose of this program is to replace the aging population
of adult razorback suckers resident to Lake Mohave with immature fish spawned by
wild populations to maintain the population's genetic diversity and viability.

• Willow Beach National Fish Hatchery. Reclamation has been working with the USFWS at
the Willow Beach National Fish Hatchery to retrofit portions of a cold water fish
hatchery facility to rear native warm-water fishes. Heating systems have been designed
and installed for the hatch house for initial rearing of eggs and larvae. Since the

SCO/CHAPT5.WPD/003672777 5-11
-------
CHAPTER 5 CUMULATIVE IMPACTS
initiation of this program, approximately 8,000 young razorback suckers have been
reared for stocking into rearing ponds at Lake Havasu (Reclamation, 1996).

• HAVFISH Project. Reclamation is an active partner of the multi-agency, Lake Havasu
Fishery Improvement Project, HAVFISH. One of the objectives of this program is to
release 25,000 razorback suckers and 25,000 bonytail into Lake Havasu over the next 10
years.

• Boulder City Golf Course Native Fish Rearing Project. Reclamation and NDOW signed an
interagency agreement with the City of Boulder City to use the ponds at the Boulder
City Golf Course for rearing native fish. During 1994, the first lake on the course was
drained, and a new liner and aeration system were installed. Approximately 1,400
juvenile razorback suckers were stocked in the ponds, and over 400 of these were
stocked into Lake Havasu in 1995. This program has since expanded with the
development of three more ponds on the golf course.

• Hualapal Native Fish Rearing Facility. Reclamation is providing technical and financial
support to the Hualapai Tribe in northern Arizona for the development of a native fish
rearing facility. This facility may raise razorback suckers, bonytail/ humpback chubs,
and other native fishes for reintroduction into the Colorado River and its tributaries
within the Grand Canyon and on tribal lands.

Native Riparian Plant Restoration. Reclamation is maintaining and expanding the
cooperative native riparian plant restoration programs initiated along the Lower Colorado
River. These partnership activities include the establishment of native plant nurseries,
demonstration plantings, enhancement projects, and research. Reclamation has committed
at least $100,000 per year for 5 years, beginning in 1996, for native riparian plant restoration.

Three-Finger Lake Project. In 1993, Reclamation and USFWS began a cooperative project to
restore Three-Finger Lake, which is located on the California side of the lower Colorado
River within the Cibola Division, south of Blythe. Approximately 120 acres of channels and
shallow backwater areas, plus one 20-acre native fish rearing pond, were dredged. This
project included the construction of the water intake system, protective levees and bankline
structures, and the planting of native riparian vegetation.

Boulder City Wetland Project The primary objective of the Boulder City Wetland Project is
to demonstrate using reclaimed municipal wastewater to restore habitat for threatened and
endangered species, and species of concern. Secondary objectives include public education
and research on improving water quality and restoring habitat for sensitive species. The
wetland receives Colorado River water blended with treated wastewater from Boulder
City's wastewater treatment plant. The blended wastewater flows through a wetland
system consisting of a stream containing shallow marshes and pools, then through four
deep-water ponds. The stream and ponds contain a variety of native wetland plants and
are bordered by native riparian plantings. Water from this wetland is used to irrigate turf at
an adjacent Veterans Cemetery.

Lower Imperial Division Wetland Enhancement. This proposed cost-share project will restore
and maintain streamflow of sufficient quality and quantity to enhance and assist in
recovering and protecting riparian/wetland and aquatic fish and wildlife habitat. The
proposed project extends from Imperial Dam upstream to Martinez Lake and encompasses
a 9.5-mile reach of the lower Colorado River, including about 3,000 acres of riparian habitat

5-12 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
and wetlands and 22 backwater lakes. The area is used extensively by waterfowl,
neotropical birds, sport fish, amphibians, mammals, songbirds, and other wildlife. Project
objectives for the California and Arizona sides of the river include: restore the historical
California channel, creating habitat for the endangered Yuma clapper rail and razorback
sucker and for other species of concern; restore inflow and outflow to approximately 20
isolated backwater lakes adjacent to the river that have been partially or totally plugged by
silt and vegetation; protect existing riparian stands of native cottonwood, willow, and
mesquite; and restore and enhance wetlands.

Las Vegas Wash Wetland Restoration. Reclamation and NFS have entered into an agreement
to construct two new wetlands totaling approximately 20 acres on the lower end of the Las
Vegas Wash near its discharge to Lake Mead. These two multipurpose wetlands are
designed to enhance marsh and riparian habitat within the eroded channel of the wash and
also to provide for the polishing of perennial effluent flows. The purpose of this effort is to
enhance habitat for the benefit of aquatic and riparian-dependent species.

MSCP Development. The Lower Colorado River MSCP is a cooperative federal/lower basin
states/tribal/ private effort to conserve Endangered Species Act-listed and sensitive species
dependent on the river. This program has the goal of benefitting more than 100 federal-, or
state-listed, candidate and sensitive species and their habitats, ranging from aquatic,
wetland and riparian, to upland.
As part of the development of this MSCP, Reclamation is generating a BA and requested
formal Section 7 consultation on its present discretional routine operations and
maintenance. Reclamation has discretion in the following areas:

• Managing target elevations of Lake Mohave, Lake Havasu, and Senator Wash Reservoir

• Making determinations of surplus, normal, and shortage conditions

• Implementing Endangered Species Act Section 7 endangered species conservation
measures, such as cooperative efforts to preserve the endangered razorback sucker and
bonytail populations in Lake Mohave and elsewhere on the Lower Colorado River

• Making management decisions on actions that affect recreation, the natural
environment, and private development (along with the activities), limited by the fact
that such decisions do not result in a new or additional consumptive use of Colorado
River water or violate other mandates as specified in the "Law of the River"

Potential Cumulative Impacts
The Endangered Species Conversation Program has been designed to result in a beneficial
impact to the region's biological resources. These plans are resulting in the recovery of
native fish populations in the Lower Colorado River, enhancement and restoration of
wetlands, restoration of native riparian plant habitat, and the conservation of federal- and
state-listed threatened endangered species and species of concern. As a result, the
beneficial project impacts of the Species Conservation Program, when considered in
conjunction with the project impacts of the Hoover Dam Bypass Project, do not contribute
to cumulative impacts.
SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
5.4.2.3 Clark County Desert Conservation Program
The desert tortoise was emergency listed as endangered in 1989 and was later changed to
threatened status in 1990. Historically, when development occurred that required the
taking of a special-status species, a Habitat Conservation Plan was necessary in order to
obtain an incidental take permit. Because of the length of time between species listings and
completion of Habitat Conservation Plans, and because of the rapid growth and
development occurring in the Las Vegas Valley CCDCP, the program was to provide a
mechanism to allow development to occur on tortoise habitat within Clark County in
exchange for the conservation of publicly owned desert tortoise habitat outside the urban
area. The intent was to achieve a balance between economic stability and long-term
environmental preservation.

The program called for the preparation of a Short-Term Habitat Conservation Plan in 1990
and a Long-Term Desert Conservation Plan, which became effective in 1995. In 1995,
USFWS approved the Lang-Term Plan and granted a 30-year incidental take permit to Clark
County. The plan is based on the funding of certain measures identified in the USFWS
Recovery Plan for the Desert Tortoise. The source of funding is a $550-per-acre mitigation
fee on development The permit area includes all private land within Clark County and all
land that becomes private through any means.

Potential Cumulative Impacts
The proposed project would be constructed on federal lands and is not directly affected by
the CCDCP. However, implementation of the preferred alternative would result in a loss of
120 acres of marginal habitat and, as indicated in Section 3.3.3 of the EIS, mitigation would
be implemented to minimize impacts on the desert tortoise. Mitigation will include
contributing project funds to the desert tortoise habitat conservation program, conducting
preconstruction surveys, relocation of affected tortoises, and construction worker education
regarding tortoises. With implementation of this mitigation, development of the proposed
project would not contribute to cumulative impacts on the desert tortoise, nor would it
conflict with the goals and objectives of the CCDCP.

5.4.3 Reasonably Foreseeable Future Projects

This section focuses on the reasonably foreseeable actions that are proposed or are in the
planning stage that would occur near the project area. The actions evaluated are roadway
improvement programs proposed for Nevada and Arizona. Provided below is a brief
description of each of these highway projects and their anticipated short-term and
long-term adverse impacts on the environment.

5.4.3.1 Boulder City/U.S. 93 Corridor Study

NDOT is conducting a Boulder City/U.S. 93 Corridor Study, the primary objectives of
which are:

Resolving traffic problems in the vicinity of Boulder City
Extending freeway status to the U.S. 93/U.S. 95 interchange
Improving operations at the junction of U.S. 93/U.S. 95
Creating a safer transportation corridor
Accommodating future transportation demand
Improving system linkage on U.S. 93 and maintaining route continuity
5-14 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
In November 1999, NDOT began an environmental study of the segment of U.S. 93 between
the Wagonwheel Interchange and the Hacienda Hotel. This project is in the environmental
study stage, and no project alternatives or alignments have been selected; however, if there
is a project as an outcome of the study, construction could begin as early as 2005. The
eastern terminus of the project is coincident with the western terminus of the U.S. 93
Hoover Dam Bypass alignment. However, the Boulder City Corridor and the Hoover Dam
Bypass are separate projects with independent utility, conceived to meet separate needs;
each could be constructed without the other, and each would still fulfill its own objectives.

Traffic analysis conducted for the Hoover Dam Bypass indicates that, if constructed on the
proposed timeline, the new bridge crossing does not generate additional traffic west of the
dam. This is because there is not currently a noteworthy volume of traffic utilizing an
alternate route.
If, however, the Hoover Dam Bypass were not constructed until 2027, the project would
result in a 24 percent increase in traffic west of the dam and in Boulder City. This is because
the gridlock at the dam would be so severe that a substantial percentage of traffic would
seek an alternate route simply due to the extensive delays at the dam. Thus, if construction
of the bypass occurs in 2027, vehicles using an alternate route would return to the bypass,
resulting an increase in traffic of approximately 24 percent (see Appendix B).

Potential Cumulative Impacts
Depending on the timing of project development, construction activities associated with the
Boulder City/U.S. 93 Corridor project could overlap with those of the Hoover Dam Bypass
Project, resulting in temporary localized air quality, traffic, noise, visual, or water quality
impacts.
Depending on site-specific conditions, a southerly bypass alternative around Boulder City
would likely have long-term adverse impacts on desert tortoise and bighorn sheep, which
are species also impacted by the dam bypass. The Boulder City/U.S. 93 Corridor bypass
alternative would also have potential cultural resource and visual impacts on the
undeveloped desert landscape to the north, south, and east of the city. However, the extent
or location of potential environmental impacts and required mitigation measures are
unknown at this time. Identification of impacts and potential mitigation measures will not
be possible until project alternatives have been fully analyzed for the Boulder City/U.S. 93
Corridor. Despite this lack of early engineering information, the potential for cumulative
impacts does exist for biological, cultural, Section 4(f), and visual resources. These are
discussed in more detail in Section 5.5.2.

5.4.3.2 U.S. 93 Widening in Arizona
The ASTIP (December 1994) has identified the Phoenix to Nevada U.S. 93 corridor as one of
the top priority corridors within Arizona. ADOT is programming and constructing various
improvements along U.S. 93 in Arizona, from south of Wickenburg to Hoover Dam.
Improvements will be phased consistent with funding levels and highway safety and
capacity priorities. Ultimately, U.S. 93 will be widened to a continuous four-lane divided
highway from Wickenburg to Hoover Dam.

ADOT will widen U.S. 93 to 4 lanes south from the new Hoover Dam Bypass interchange to
the improved four-lane divided section 13 miles to the south at the LMNRA boundary.
This segment of roadway is the final link between 1-40 near Kingman and the Arizona
terminus of the Hoover Dam Bypass Project. This widening could be done either

SCO/CHARTS. WPD/003672777 5'15
-------
CHAPTER 5 CUMULATIVE IMPACTS
concurrently with construction of the Hoover Dam Bypass or soon after its completion.
However, if the dam bypass is not constructed, the U.S. 93 widening will still proceed when
ADOT determines traffic congestion in this restricted capacity two-lane section reaches
unacceptable levels. If this widening is not completed, the 13-mile segment will create a
regional traffic bottleneck between the proposed four-lane Hoover Dam Bypass and 1-40, as
well as south of 1-40 to Phoenix (once the widening of U.S. 93 between Wickenburg and
Kingman occurs).

Potential Cumulative Impacts
This work may occur either concurrently with or soon after construction of the Hoover Dam
Bypass Project, potentially resulting in cumulative short-term impacts on air quality, traffic,
noise, visual, and water quality. In addition, long-term impacts to biological, cultural, and
parkland resources may occur, depending on site-specific conditions. However, the
impacts could be reduced by reuse of some of the old highway alignment, which is already
disturbed (see Section 5.5.2.2); there are several sections where this is a possibility.
Nonetheless, the ADOT U.S. 93 widening project has the potential for cumulative impacts
to biological, cultural, and Section 4(f) resources. These impacts are discussed in more
detail in Section 5.5.2.

5.4.3.3 U.S. 95 Widening in Nevada

NDOT has a project listed in the long-range element of the Transportation System Projects
list to widen the two-lane segment of U.S. 95 from the California/Nevada state line west of
Laughlin to U.S. 93 west of Boulder City. This segment of U.S. 95 will be widened to a
four-lane divided highway based on funding availability and traffic demand.
Improvements to U.S. 95 will be a three-stage project. The first third to be designed and bid
will be from Searchlight to a point approximately 18 miles north; $18 million is funded and
construction is targeted for fall 2001. The second third of the highway to be improved
would be the southern 20-mile section; the anticipated cost is about $19 million, and it
would be constructed about 1 year later if funding is available. The final stage is the
northern third of U.S. 95; it is approximately 18 miles long, would cost about $18 million,
and would be constructed as soon as funding became available.

Potential Cumulative Impacts
This program of improvements to U.S. 95 is in the very early planning stages, and few
details about the project or potential environmental impacts are currently available from
NDOT. Since the project is being funded and designed in three stages starting far south of
Hoover Dam, there is no potential for cumulative short-term impacts from construction
because the final stage will not likely be built until after completion of the Hoover Dam
Bypass. Furthermore, no cumulative traffic operational impacts are foreseen because the
highway users are different; most of the traffic on U.S. 95 is traveling to and from Las Vegas
with no intention or need to go through Boulder City and/or Hoover Dam. Long-term
impacts to biological and cultural resources may occur, depending on site-specific
conditions; however, impacts will be very small because all of the work will be within
previously disturbed right-of-way. Therefore, the NDOT U.S. 95 widening project has the
potential for cumulative impacts to biological and cultural resources, but no engineering or
environmental details are available at this time. NDOT is currently preparing an
Environmental Assessment (EA) for the entire route (about 60 miles).
5-16 SCO/CHARTS. WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
5.4.3.4 SR 68, Bullhead City - East, Widening in Arizona
From its junction with SR 95 in Bullhead City, Arizona, 14.6 miles of SR 68 is being widened
(from MP 1.2 to MP 14.5) so that the roadway will have four travel lanes all the way to its
terminus at U.S. 93. SR 68 is currently a four-lane roadway from MP 14.5 to U.S. 93, and it
provides the only east-west roadway linking U.S. 93 near Kingman with Laughlin, Nevada,
across the Colorado River from Bullhead City. ADOT traffic studies determined that a
minimum of two eastbound and two westbound travel lanes were required to provide
adequate operational characteristics and driver safety. This project is currently under
construction. An environmental assessment (EA) was completed for this project in June
1999 (ADOT, 1999).

Potential Cumulative Impacts
Construction on this project was started in September 2000 and is scheduled to be
completed in the fall 2001. Approximately 127 acres will be disturbed by project
construction. The Draft and Final EAs for this project evaluate the potential for cumulative
impacts to biological, Section 4(f), and visual resources. These impacts are discussed in
more detail in Section 5.5.2.

5.5 Cumulative Environmental Impacts

Certain impacts associated with the proposed U.S. 93 Hoover Dam Bypass Project could
arise which, in conjunction with impacts attributable to other projects (either in the
immediate vicinity or with similar characteristics), could have the potential to result in
collectively adverse effects to the environment that are of greater significance than those
generated individually by the proposed project. Cumulative impacts could include those
effects considered to be less than significant individually, but which could become
significant when evaluated in relation to impacts from other projects.

5.5.1 Potential Cumulative Impacts

This section describes the cumulative impacts to environmental resources mat could
potentially arise with implementation of the proposed Hoover Dam Bypass Project in
association with the other projects and programs described in this chapter. This discussion
is presented by environmental resource areas. Because NPS, Reclamation, or Clark or
Mohave counties do not propose development in or near the project area, no impacts on the
environment would be expected, and the proposed project would not contribute to
cumulative impacts. Therefore, the cumulative effect analysis focuses on the major
roadway improvements that are planned to occur in the immediate vicinity of the proposed
project and could result in environmental impacts that, when combined with those of the
proposed project, have the potential to result in cumulative impacts.

5.5.1.1 Biological Resources
On June 3,1999, USFWS issued its Biological Opinion for the Hoover Dam Bypass Project.
This document represents the opinion of USFWS on the potential effects of the proposed
bypass project on federally listed species under the Endangered Species Act of 1973. The
Biological Opinion concluded that the project will not likely affect the following
endangered species: bald eagle, American peregrine falcon, razorback sucker, southwestern
willow flycatcher, bonytail chub, and Devil's Hole pupfish. For the Mojave desert tortoise,
a federally listed threatened species, USFWS found that the project is not likely to

SCO/CHAPT5.WPD/003672777 5'17
-------
CHAPTER 5 CUMULATIVE; IMPACTS
jeopardize its continued existence or adversely impact designated critical habitat. USFWS
stipulated "reasonable and prudent" measures to minimize project effects on the desert
tortoise, including payment of $46,960 to Clark County for offsite mitigation for the loss of
80 acres of desert tortoise habitat. This EIS also concluded that the Hoover Dam Bypass
preferred alternative will impact 20 acres of known habitat of desert bighorn sheep, which
is a USFWS species of concern, as well as a State of Nevada protected and State of Arizona
threatened species.

There is insufficient environmental and engineering information available for the future
U.S. 93 and U.S. 95 highway improvement projects to identify potential cumulative impacts
on endangered, threatened, or protected species also affected by the Hoover Dam Bypass.
However, since these two future projects will primarily involve widening of existing
highways, it is assumed mat additional adverse impacts can usually be avoided with
environmentally sensitive design, including continued use of protected game crossing
structures, right-of-way fencing to minimize animal mortality, and other measures,
including roadside signing for wildlife areas. Lands immediately adjacent to major
highways are generally low-value biological habitats because of their highly disturbed
nature. Hence, no cumulative biological impacts are anticipated from these future projects.

In contrast, the Boulder City /U.S. 93 Corridor alternatives have the potential for cumulative
impacts on biological resources also impacted by the Hoover Dam Bypass. A new highway
around Boulder City would fragment the existing habitat and essentially isolate most biota
now occupying the area between the existing U.S. 93 corridor and any bypass route. As a
result of any new highway, human development of the affected area may be accelerated,
eventually causing its entire loss as wildlife habitat. The worst-case alternative for
biological resources would be a southern bypass similar to that defined in NDOT's 1994
U.S. 93 Colorado River Crossing Corridor Study. The primary difference between the
potential project alternatives is the greater habitat loss associated with the approximately
14-mile southern corridor. Considerably more impact to the desert tortoise can be
anticipated with a southern alternative, because this corridor cuts through almost
continuous tortoise habitat from the point it departs the U.S. 93/U.S. 95 interchange to the
point at which it exits the Eldorado Valley and enters the Eldorado Mountains east of
Boulder City. The new .alignment alternatives for the Boulder City/U.S. 93 Corridor project
also have the potential to impact local populations of desert bighorn sheep, which range
throughout the River Mountains, often entering the lower slopes and even occasionally
crossing U.S. 93. Therefore, although NDOT has not completed environmental and
engineering studies for the Boulder City/U.S. 93 Corridor, it is likely that a bypass
alternative on new (undisturbed) alignment will impact two special-status wildlife species
also impacted by the Hoover Dam Bypass - the desert tortoise and desert bighorn sheep -
and thus collectively cause a cumulative impact on these resources. The cumulative acreage
of impacted habitats will not be known until NDOT completes preliminary design for the
Boulder City/U.S. 93 Corridor.

The SR 68 project has the potential for cumulative impacts to desert bighorn sheep. This
project traverses important desert bighorn sheep habitat in the Black Mountains of
northwestern Arizona. This habitat was already fragmented by the existing highway,
which has effectively split the population for 40 or more years. The construction of two
wildlife crossings designed and situated primarily for use by bighorn sheep is part of the
proposed mitigation for the project. If successful (i.e., desert bighorn sheep use the
crossings), this project could result in a net beneficial impact to desert bighorn sheep.

5-18 SCO/CHARTS. WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
However, this roadway improvement would result in a disturbance of approximately 90
acres of desert bighorn sheep habitat. Therefore, the Hoover Dam Bypass and the SR 68
widening projects would cumulatively impact 110 acres of bighorn sheep habitat; however,
both projects include game crossings to minimize the effect on sheep movement.

USFWS considered cumulative effects in their June 1999 Biological Opinion for the Hoover
Dam Bypass and concluded that future federal actions unrelated to the proposed project
will require separate consultation pursuant to Section 7 of the Endangered Species Act.
Since the majority of the land surrounding the proposed project is administered by
Reclamation, NFS, or BLM, any action on those lands will be subject to consultation under
Section 7. USFWS further concluded that actions on private lands within Clark County are
expected to increase as the human population increases. The rapid growth of the human
population, as well as tourism, has resulted in loss and degradation of desert tortoise
habitat and loss of individual tortoises. These impacts are expected to continue according
to USFWS. However, the CCDCP and associated incidental take permit addresses take of
desert tortoises and destruction of their habitat from future development projects on
nonfederal lands within Clark County. USFWS anticipates that measures in the CCDCP
will continue to mitigate and minimize such effects.

5.5.1.2 Archaeological/Historical (Section 106) Resources
The U.S. 93 Hoover Dam Bypass will not impact significant prehistoric archaeological
resources. However, it will have an adverse effect on the HDNHL, some contributing
features, and the Gold Strike Canyon and Sugarloaf Mountain Traditional Cultural Property
(TCP) within the area of potential effects of the preferred alternative.

Considering the nearby foreseeable future highway projects described in Section 5.4.3, on
the Nevada side there are no recorded prehistoric sites of known significance within the
potential alignments for development of the U.S. 93 Boulder City Corridor. The only
reported prehistoric sites are isolated lithic flake scatters, ceramics, and milling stone
stations located on the broad alluvial fan east of the Boulder City Airport. However, larger
prehistoric archaeological sites, such as rockshelters, campsites, and rock alignments are
situated in the River Mountains north of Boulder City, and the Eldorado Mountains to the
east contain similar prehistoric resources including prehistoric turquoise mines. Historic
sites in the Boulder City area include the Sullivan Turquoise Mines near Hacienda Hotel
and in Hemenway Valley; potential remains from the Alunite Mining District and Boulder
Annex Townsite near Railroad Pass; historic power transmission lines emanating from the
Hoover Dam generating stations to locations in California, Arizona, and Nevada; a Union
Pacific Railroad Line from Boulder City to the dam for which berms, bridges, and other
features can still be found; and the Boulder City National Register Historic District, which
could be affected by improvements to existing U.S. 93 through town. Considering the
adverse effect of the preferred alternative on HDNHL and related features, there is a
potential for consequential cumulative impacts on this resource due to the possibility of
impacts from a Boulder City Corridor alternative on the power transmission lines
emanating from the dam, which were found eligible for the National Register as
contributing elements to the HDNHL. Furthermore, a Boulder City/ U.S. 93 Corridor
Alternative could have a cumulative impact on the Goldstrike Canyon and Sugarloaf
Mountain TCP, which is adversely affected by the Hoover Dam Bypass and is located
approximately 0.75 mile east of the Hacienda Hotel and south of existing U.S. 93. However,
the exact nature and limits of any significant cultural resources potentially affected by the
Boulder City Corridor will not be known until detailed studies are completed by NDOT.
SCO/CHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
On the Arizona side, the abandoned former roadway of U.S. 93 was evaluated within the
area of potential effects of the Hoover Dam Bypass. It was found eligible for the National
Register for its association with the construction of Hoover Dam. The roadway recorded
here is a fill or grade extending from the current highway on the north and running
southward roughly parallel to the current highway route. The surface retains some gravel
and small pieces of asphalt. This ffll-and-cut segment is a portion of the original route of
U.S. 93, as it was built in the late 1930s. The contract for construction of Hoover Dam
included provisions for completing approaches to the dam for the highway to Las Vegas,
Nevada, and a road to Kingman, Arizona. The approaches to Hoover Dam on both sides of
the canyon were widened in 1957, and it is possible the recorded segment was abandoned
at that time. However, there is certainly the potential for other historic resources, as well as
prehistoric archaeological sites along the U.S. 93 corridor in Arizona that might be impacted
by widening the highway, especially if it were done on a new alignment. More specific
information on potential cultural resources that could be affected by me widening of U.S. 93
in Arizona will not be available until environmental studies are completed for mis project,
but no National Register resources are presently known that may be affected and mat
would result in a cumulative impact when considered collectively with the dam bypass
effects.

5.5.1.3 Section 4(f) Resources

The preferred alternative for the Hoover Dam Bypass permanently uses approximately
92 acres of Section 4(f) lands from the LMNRA, the HDNHL, and the National Register
eligible TCP. It was determined that there are no feasible and prudent alternatives to the
use of Section 4(f) land and that the proposed action includes all possible planning to
minimize harm to the Section 4(f) lands resulting from their use.

NDOT's Boulder City/U.S. 93 Corridor Study alternatives may impact land within the
LMNRA located northeast of Boulder City, between the eastern limit of the project and the
recreation area boundary. Using an assumed general highway right-of-way section of
300 feet, as was done for the U.S. 93 Hoover Dam Bypass, the Boulder City Corridor could
result in permanent use of over 50 acres of Section 4(f) land from the LMNRA if a southern
bypass alternative were selected. Other potential alternative corridors have not been
studied fully by NDOT, and the extent of their potential Section 4(f) impact cannot be
estimated at this time.

Widening of the 13-mile two-lane segment of U.S. 93 in Arizona, from the future Hoover
Dam Bypass interchange to the boundary of the LMNRA, would use Section 4(f) recreation
land administered by NFS. In some areas, ADOT has 400 feet of existing highway
right-of-way; however, at this predesign stage it is unknown what portions of the widening
would be on LMNRA or ADOT land. If ADOT did the widening on the existing alignment
of U.S. 93, it is estimated that an additional 50 feet of right-of-way would be required.
Assuming all the new highway right-of-way would be on LMNRA land, this ADOT project
could result in the permanent use of approximately 80 acres of Section 4(f) land.

Based on the location of existing U.S. 93 through the LMNRA, there is no feasible and
prudent alternative to the use of Section 4(f)-protected land for either the proposed Boulder
City/US. 93 Corridor or the U.S. 93 widening in Arizona. Thus, these two reasonably
foreseeable future projects in the immediate vicinity of the Hoover Dam Bypass would have
the potential to generate Section 4(f) impacts that, when addressed collectively with the
proposed project, could result in a considerable cumulative impact to public recreation and

5-20 SCCVCHAPT5.WPD/003672777
-------
CHAPTER 5 CUMULATIVE IMPACTS
historic lands. Impacts to Section 4(f) resources from improvements to SR 68 through the
LMNRA were evaluated for the project and appended to the Final EA (ADOT, 1999). The
evaluation concluded that expanding the roadway through the LMNRA will not
substantially impair the activities, features, or attributes of the Section 4(f) resource, either
by direct impacts (land takings for easements) from MP 1.6 to MP 2.0 or by constructive
use/proximity impacts from MP 1.23 to MP 1.6. The total area of LMNRA required is 1.92
acres.
The four highway projects together could permanently use approximately 224 acres of land
from the LMNRA, the HDNHL, and TCP. However, this potential cumulative impact to
Section 4(f) land from the four highway projects would still be substantially less than five of
the alternative alignments considered for the Hoover Dam Bypass: Willow Beach North,
Willow Beach South, Nelson, Cottonwood, and Temple Bar (see Table 2-1).

5.5.1.4 Visual Resources
The preferred Sugarloaf Mountain alignment for the Hoover Dam Bypass will be located
approximately 1300 feet downstream from Hoover Dam and about 254 feet higher than the
crest of the dam (see Figure 2-9). This new bridge crossing over Black Canyon will be in full
view from the dam (see Figure 3-10). Consequently, it was found to have an adverse effect
on the historic landmark owing to the introduction of visual elements that diminish the
integrity of the property's significant historic features (36 CFR 800.5). This EIS determined
that other visual effects of the Hoover Dam Bypass on the surrounding environment could
be mitigated (see Section 3.7).

NDOT's planned Boulder City and U.S. 95 highway improvements and ADOT's planned
U.S. 93 widening will likely have both short-term and long-term visual impacts on the
surrounding desert environment. However, the planned U.S. 93 and U.S. 95 improvements
will be all within existing highway corridors, which have been a part of the desert
landscape for many decades and, therefore, may not have adverse visual impacts. Of these
three foreseeable future projects, only the Boulder City Corridor alternatives have the
potential for substantial visual impacts on presently undeveloped desert landscape, which
is located in the Eldorado Valley to the south and the Colorado River and Eldorado
Mountains to the north and east. As discussed under Archaeological and Historic
Resources (Section 5.5.2.2), the Boulder City Corridor southern bypass alternative could
contribute to a cumulative impact on historic features related to Hoover Dam (i.e., the
power transmission lines). However, even if a southern bypass were the selected
alternative, these transmission lines are not part of the historic viewshed of Hoover Dam;
therefore, it does not appear that development of the Boulder City Corridor would
contribute to a cumulative visual impact on the HDNHL.

Improvements underway on SR 68 will result in some long-term impacts to visual
resources. These impacts result from the loss of some rock spires and other visual features,
increased rock cuts, and a change in the overall character in some areas of the project.
However, due to its location, SR 68 will have no cumulative impacts to HDNHL visual
resources.
SCO/CHAPT5.WPD/003672777 5-21
-------
CHAPTER 5 CUMULATIVE IMPACTS
This page intentionally left blank.
5-22 SCO/CHAPT5.WPD/003672777
-------
CHAPTER 6
Section 4(f) Evaluation
Introduction

6.1 Purpose of Section 4(f) Evaluation
Section 4(f) of the US. Department of Transportation Act of 1966, codified in Federal law at
49 U.S.C. § 303, declares that, "it is the policy of the United States government that special
effort should be made to preserve the natural beauty of the countryside and public park and
recreation land, wildlife and waterfowl refuges, and historic sites." Section 4(f) specifies
that, "the Secretary [of Transportation] may approve a transportation program or project...
requiring the use of publicly owned land of a public park, recreation area, or wildlife and
waterfowl refuge of national, State, or local significance, or land of an historic site of
national, State, or local significance (as determined by the Federal, State, or local officials
having jurisdiction over the park, area, refuge, or site), only if—
1. There is no feasible and prudent alternative to using that land; and
2. The program or project includes all possible planning to minimize harm to the park,
recreation area, wildlife and waterfowl refuge, or historic site resulting from the
use.
The use of Section 4(f) resources occurs when: (1) land from a Section 4(f) site is
permanently acquired for a transportation project, (2) when there is a temporary occupancy
of land that is adverse in terms of the statute's preservation purpose, or (3) when the
proximity impacts of the transportation project on the Section 4(f) site, without acquisition
of land, are so great that the purposes for which the Section 4(f) site exists are substantially
impaired. The latter type of use is also known as a "constructive use." Constructive use
occurs when the transportation project does not incorporate land from a Section 4(f)
resource, but the project's proximity impacts are so severe that the protected activities,
features, or attributes that qualify a resource for protection under Section 4(f) are
substantially impaired. Constructive use has been determined to occur under the following
cases (23 CFR 771.135[p]):
• The projected noise level increase attributable to the project substantially interferes with
the use and enjoyment of a noise-sensitive facility of a resource protected by Section 4(f).
• The proximity of the proposed project substantially impairs aesthetic features or
attributes of a resource protected by Section 4(f), where such features or attributes are
considered important contributing elements to the value of the resource.
• The project results in a restriction on access which substantially diminishes the utility of
a significant publicly owned park, recreation area, or historic site.
• The ecological intrusion of the project substantially diminishes the value of wildlife
habitat in a wildlife or waterfowl refuge adjacent to the project or substantially
interferes with the access to a wildlife or waterfowl refuge, when such access is
necessary for established wildlife migration or critical life cycle processes.

Section 4(f) is applicable to historic sites and archaeological resources when the resource is
included on, or eligible for, the NRHP (23 CFR 771.135[e]). Section 4(f) does not apply to

SCO/CHAPT6.WPD/003672782 ^
-------
CHAPTER 6 SECTION 4(F) EVALUATION
archaeological sites where it is determined after consultation with the SHPO and the ACHP
that the resource is important chiefly because of what can be learned by data recovery and
has minimal value for preservation in place. Constructive use is defined as not occurring
when compliance with the requirements of Section 106 of the NHPA (16 U.S.C. § 470) and
related regulations for proximity impacts of a proposed project on an NRHP site results in a
finding of "no effect" or "no adverse effect" (36 CFR 800.5).

Section 4(f) further requires consultation with the Department of the Interior (DOI), and as
appropriate, the involved offices of the Departments of Agriculture and Housing and Urban
Development in developing transportation projects and programs which use lands
protected by Section 4(f).

Because the Hoover Dam Bypass Project would use Section 4(f) lands, this evaluation
identifies significant Section 4(f) resources in the project area, describes the nature and
extent of the use of these significant properties, evaluates alternatives mat would avoid the
use of Section 4(f) resources, and describes measures to minimize harm to the affected
resources.

6.2 Proposed Project

6.2.1 Introduction

U.S. 93 is a primary highway that traverses the western part of the nation from Montana to
Arizona. U.S. 93 functions as a principal arterial highway providing a north-south
transportation corridor and is an integral part of the State and national highway systems.
In addition to the interstate commerce that uses this route, vacationers from throughout the
country use U.S. 93 in their travels between Phoenix, Arizona, and Las Vegas, Nevada, and
points beyond.

The present route of U.S. 93 uses the crest of Hoover Dam as a bridge to cross the Colorado
River. The proposed project would remove trucks and through-vehicular traffic from the
crest of Hoover Dam by rerouting U.S. 93 to a new bridge crossing and associated approach
highways. This new route would reduce or eliminate the steep grades, sharp curves,
narrow highway width, substandard shoulders, poor sight distances, and low travel speeds
of the existing route.

6.2.2 Purpose and Need

A complete discussion of the purpose and need for the project is provided in Chapter 1 of
this EIS and is incorporated herein by reference.

The purpose of the project is to reduce or eliminate through traffic over Hoover Dam to:

• Minimize the potential for pedestrian-vehicle accidents on the dam crest and on the
Nevada and Arizona approaches to the dam

• Remove a major bottleneck to interstate and international commerce and travel in the
west by reducing traffic congestion and accidents in this segment on the major
commercial route between Phoenix and Las Vegas

• Replace an inadequate federally owned highway river crossing with a new crossing that
meets current roadway design criteria, and improves through-vehicle and truck traffic
capacity on U.S. 93 at the dam
6-2 SCO/CHAPT6.WPD/003672782
-------
CHAPTER 6 SECTION 4(F) EVALUATION
• Reduce travel time in the dam vicinity

• Protect Hoover Dam employees, visitors, equipment, power generation capabilities, and
Colorado River waters while enhancing visitors' experiences at Hoover Dam by:

- Safeguarding dam and power plant facilities and the waters of Lake Mead and the
Colorado River from hazardous spills or explosions

- Protecting the dam and power plant facilities from interruptions in electricity and
water delivery

- Providing improved conditions for operating and maintaining Hoover Dam facilities

6.2.3 Project Alternatives Using Section 4(f) Lands

A complete discussion of the project alternatives is provided in Chapter 2 and is
incorporated herein by reference. A listing of these alternatives and the Section 4(f) acreage
used is provided below (see Section 2.2 for details).

Alternatives Using Section 4(f) Lands
• Promontory Point (74 acres)
• Sugarloaf Mountain (92 acres)
• Gold Strike Canyon (128 acres)

Alternatives Using Section 4(f) Lands, Considered but Eliminated (see Figure 2-1)

Boulder City North (145 acres)
Boulder City South (165 acres)
Boulder City South Option (135 acres)
Willow Beach North (405 acres)
Willow Beach South (575 acres)
Nelson (491 acres)
Cottonwood (436 acres)
Temple Bar (818 acres)
Laughlin-Bullhead City (36 acres)
Modifications to Hoover Dam
- Option for widening Hoover Dam
- Option for elevated highway on Hoover Dam

6.2.3.1 Promontory Point Alternative
The Promontory Point Alternative would cross Lake Mead about 1,000 feet upstream of
Hoover Dam and would require construction of approximately 2.7 miles of approach road
in Nevada, a 2,200-foot bridge over Lake Mead, and 0.8 mile of approach road in Arizona.
The three bridge types that are considered in the E3S for this alternative are a steel truss rib
through-arch bridge, a concrete cable-stayed bridge, and a steel suspension bridge.
However, presentation of specific bridge designs in this EIS is not intended to preclude
other feasible structures. The Promontory Alternative would include six wildlife
underpasses, one highway bridge, and one tunnel. Fencing would be placed along both
sides of the highway corridor to guide wildlife to the crossing structures.
SCO/CHAPT6.WPD/003672782 6'3
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.2.3.2 Sugarloaf Mountain Alternative (Preferred Alternative)
The Sugarloaf Mountain Alternative would cross the Colorado River about 1,500 feet
downstream of Hoover Dam and would require constructing approximately 2.2 miles of
highway approach in Nevada, a 1,900-foot bridge, and approximately 1.1 miles of highway
approach in Arizona. Bridge types considered in the EIS for this alternative are a concrete
or steel deck arch bridge and a concrete cable-stayed bridge; however, presentation of
specific bridge designs in this EIS is not intended to preclude other feasible structures. A
Design Advisory Panel will provide input on bridge design concepts, structure type, and
materials (see Section 3.5). The Sugarloaf Mountain Alternative would include four wildlife
underpasses, three wildlife overpasses, two highway bridges (which also serve as wildlife
crossings), and a tunnel. Fencing would be placed along both sides of the highway corridor
to guide wildlife to the crossing structures.

6.2.3.3 Gold Strike Canyon Alternative
The Gold Strike Canyon Alternative would cross the Colorado River about 1 mile
downstream of Hoover Dam and would require construction of approximately 2.2 miles of
approach road in Nevada, a 1,700-foot bridge, and 1.1 miles of approach road in Arizona.
The bridge types considered in the EIS for mis alternative are a concrete deck arch bridge
and a steel deck arch bridge; however, presentation of specific bridge designs in this EIS is
not intended to preclude other feasible structures. The Gold Strike Canyon Alternative
would include two wildlife underpasses, one wildlife overpass, ten highway bridges, and
one tunnel. Noise barriers could be constructed on the outside shoulder along the roadway
facing the trail through Gold Strike Canyon to reduce noise impacts on the hiking trail.
Fencing would be placed along both sides of the highway corridor to guide wildlife to the
crossing structures.

6.2.4 Other Alternatives Considered, But Eliminated

Following completion of the Phase A Study (Reclamation, October 1991; see Chapter 1 for
more details), the PMT1 agreed (Memorandum, January 1991) that all alternatives except for
Promontory Point, Sugarloaf Mountain, and Gold Strike Canyon be eliminated from further
consideration. After analyzing the alternatives under specific screening criteria
(Section 2.3), all were eliminated from further consideration except for the three alignments
closest to Hoover Dam: Promontory Point, Sugarloaf Mountain, and Gold Strike Canyon.
The other alternatives were eliminated for reasons described below:

1. Some alternative routes did not meet the project purpose and need because they would
not substantially eliminate roadway deficiencies and reduce traffic congestion on
U.S. 93 at Hoover Dam and dam approaches, eliminate through traffic from the dam,
enhance public safety, or protect Hoover Dam and its visitors. Alternatives were also
dropped from further consideration if they substantially increased travel time and did
not provide system continuity to enhance travel within the U.S. 93 corridor. The
lrThe PMT is currently an interagency team composed of the Federal Highway Administration -
Central Federal Lands Highway Division, National Park Service, the Arizona and Nevada Divisions
of the Federal Highway Administration, the Arizona and Nevada Departments of Transportation,
and the Bureau of Reclamation. The PMT was established in 1989 to oversee project planning,
environmental studies, design development, and project funding. The PMT representatives from
these agencies have participated in reviews of the proposed project area, environmental studies,
preliminary engineering, and the DEIS throughout the planning process.

6-4 SCO/CHAPT6.WPD/003672782
-------
CHAPTER 6 SECTION 4(F) EVALUATION
Laughlin-Bullhead City Alternative was eliminated because motorists would avoid
driving 23 additional miles by continuing to use the Hoover Dam crossing. Therefore,
meeting the objectives of enhanced safety, improved level of service, and reduced
congestion on U.S. 93 at the dam would not be achieved.

2. Except for U.S. 95/1-40, all of the build alternatives would affect Section 4(f) lands;
however, some routes have considerably more impact than others. The Temple Bar
Alternative and all the highway alternatives south of Gold Strike Canyon except the
Laughlin-Bullhead City and U.S. 95/1-40 Alternatives would affect much more Section
4(f) land than the three alternatives near Hoover Dam. Based on the requirement to
minimize harm to Section 4(f) property, these southerly alternatives were eliminated
from further consideration.

4. Alternatives were eliminated from consideration because their impacts on known
peregrine falcon breeding areas, bighorn sheep habitat and movement corridors, desert
tortoise habitat, and other wildlife were more severe than the three alternatives near the
dam.
5. The cost of constructing the alternative routes generally increases as the length of the
route and the distance from the dam increases. The higher costs of the Hoover
Dam/Boulder City Bypass ($317 million) and Willow Beach South ($409 million) routes
were added justification for their elimination from further consideration (NDOT, 1994).

6. The Laughlin-Bullhead City Alternative would result in additional total 20-year costs of
approximately $1.4 billion over the alternatives studied in detail, due to the increased
length of the alternative (see Appendix B).

7. Alternatives that require keeping the existing highway open to through traffic to
provide visitor access to the dam were dropped from further consideration if they also
required operating and maintaining extensive lengths of duplicate highway.
Alternative routes not close to Hoover Dam (Willow Beach, Nelson, Cottonwood, and
Temple Bar) were eliminated for this reason.

(See Chapters 1 and 2 for additional information about these routes.)

6.2.4.1 Modifications to Hoover Dam
This alternative was examined with two options for modifications to existing U.S. 93 on the
crest of Hoover Dam:

• Option for Widening Hoover Dam. This option would widen the dam crest and connect it
to the existing highway near each abutment, which would result in more traffic lanes
through the dam area with no significant improvement in traffic flow. Tourist traffic
would not be separated from the through traffic, and traffic interference with dam
maintenance operations would still occur. Constructing new highway approaches to fit
a widened dam crest would require large amounts of earthwork and complex approach
structures.
SCO/CHAPT6.WPD/003672782 6-5
-------
CHAPTER 6 SECTION 4(F) EVALUATION
• Option for Elevated Highway on Hoover Dam. This option was examined to attempt to
attain the desired highway design criteria by adding an elevated crossing structure
(which would be supported by some portion of Hoover Dam). It would require entirely
new and straighter highway approaches. Extremely deep and lengthy excavations, or
possibly runnels, would be necessary to connect such a structure to the existing
highway.

Both options of this alternative were eliminated because:

1. The approach roads to the dam have sharp switchback curves with radii less than
100 feet and grades as steep as 7 percent. Because of these existing restrictive
conditions, the design criteria for a four-lane highway with a maximum 6 percent grade
and a minimum curve radius of 1300 feet could not be met by making reasonable
improvements to the existing highway.

2. It would result in signif icant adverse impacts to the historical significance of the
site—the integrity and setting of the dam and its status as an NHL.

3. It would cause interference with the Hoover Dam Visitor Center and further complicate
conditions for separation of traffic, vehicle-turning movements/ and parking maneuvers.

4. It does not solve the problems of safety to the public, does not protect the power and
water supplies, and does not improve the situation of interference with operations and
maintenance of the dam facilities.

5. No practical way exists to make these modifications without major impacts to the
historic appearance of the dam and disruption to traffic during construction.

6.3 Section 4(f) Properties

Because of the unique situation of Section 4(f) lands within the LMNRA being continuous
from 40 miles north, where the LMNRA meets the Grand Canyon National Recreation Area,
to 60 miles south of the existing corridor, it is not possible to avoid these lands and still
maintain the service that existing U.S. 93 provides for this area of the West (Figure 6-1).

There are three primary Section 4{f) properties involved with the proposed action—the
LMNRA, the HDNHL, and a traditional cultural property (TCP) determined eligible for the
National Register of Historic Places. LMNRA encompasses approximately 1,482,476 acres
of federal land and 28,212 acres of nonfederal land and is managed by the NPS. The
HDNHL encompasses approximately 330 acres of federal land mat is managed by
Reclamation as a part of the Hoover Dam Reservation Area (HDRA). The HDRA was
reserved specifically for reclamation and power generation purposes and for the protection
and security of the dam power plant and associated facilities. Areas within the HDRA, and
not within the HDNHL or TCP, are not considered 4(f) property.

The LMNRA was established October 8,1964, by Public Law 88-639, for "the general
purpose of public recreation, benefit, and use, and in a manner that will preserve, develop,
and enhance—the recreation potential and in a manner mat will preserve the scenic, historic,
scientific, and other important features of the area."
SCCyCHAPT6.WPD/003672782
-------
» US. M I W
i
f • • 10 .1t_.
EXPLMW1M

O M»totOm\wdtn»

O Bddk>iflni0i«MdAeeww Point
FIGURE 6-1

LAKE MEAD NATIONAL

RECREATION AREA
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 6 SECTION 4(F) EVALUATION
This page intentionally left blank
6-8 SCO/CHAPT6.WPD/003672782
-------
CHAPTER 6 SECTION 4(F) EVALUATION
The LMNRA and the HDNHL include a wide variety of scenic and recreational resources.
Most of the LMNRA is arid desert. Rugged mountains, expansive alluvial fans, and dry
washes dominate the landscape. The LMNRA encompasses two reservoirs formed by the
Colorado River: (1) Lake Mead, 110 miles long and formed by Hoover Dam, has
162,677 acres of water surface and more than 822 miles of shoreline; and (2) Lake Mohave,
67 miles long and formed by Davis Dam, has 28,800 acres of water surface and more than
254 miles of shoreline (Figure 6-1).

This ruggedly scenic area is famous for Hoover Dam, Lake Mead, the Colorado River,
recreational activities, and wildlife. Attributes identified by the NPS that contribute to the
overall quality and management of the LMNRA include aesthetics, cultural, historic,
recreational, noise, air, and existing natural or biological resources. Potential impacts to
these attributes by the proposed project are summarized in Chapter 3.

The recreational activities available in the LMNRA include sightseeing, hiking, camping,
picnicking, backpacking, fishing, hunting, boating, river rafting, and bicycling. In 1997,
there were 9.7 million visitors to the LMNRA. More than 1 million visitors toured Hoover
Dam in 1997. The LMNRA and Hoover Dam are popular tourist destination areas, both
nationally and internationally.

6.4 Impacts on the Section 4(f) Properties

As defined in the introduction, the use of a Section 4(f) resource occurs either when land
from a Section 4(f) site is permanently acquired for a transportation project, when
temporary occupancy has adverse effects, or when the proximity impacts of the project on
the Section 4(f) site are so great that the purposes for which the Section 4(f) site exists are
substantially impaired. Table 6-1 presents a simplified summary of Section 4(f) impacts that
each alternative would have if implemented. The Hoover Dam Bypass project alternatives
would impact three primary Section 4(f) properties: the LMNRA, which is a federal public
park and recreation land, the HDNHL, which is listed in the National Register, and a
National Register-eligible TCP. No wildlife or waterfowl refuges are located in the vicinity
of the proposed project. No National Register-eligible archaeological sites have been
identified within the project's area of potential effects (APE); however, one archaeological
site within the APE was found to be a contributing element of the TCP. Acreage impacts on
Section 4(f) lands are shown graphically in Figure 6-2.

As discussed in the introduction, constructive use is defined as not occurring when
compliance with the requirements of Section 106 of the NHPA (16 U.S.C. § 470) and related
regulations for proximity impacts of a proposed project on an NRHP site results in a finding
of "no effect" or "no adverse effect" (36 CFR 800.5). However, pursuant to the ACHP
regulations implementing Section 106, an undertaking is considered to have an adverse
effect when the effect on a historic property may diminish the integrity of the property's
location, design, setting, materials, workmanship, feeling, or association. Adverse effects
on historic properties include, but are not limited to: (1) physical destruction of or damage
to all or part of the property; (2) change of the character of the property's use or of physical
features within the property's setting that contribute to its historic significance; and
(3) introduction of visual, audible, or atmospheric elements that diminish the integrity of
the property's significant historic features (36 CFR800.5 [a]).
SCO/CHAPT6.WPD/003672782
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.4.1 Promontory Point Alternative

The Section 4(f) properties and/or resource values were identified and assessed for
potential impact by the Promontory Point Alternative. The following summarizes the
results of that effort. (A more detailed description of these analyses and conclusions can be
found in Chapter 3.)

6.4.1.1 Park Land and Recreation

The Promontory Point Alternative would permanently use a total of 74 acres of Section 4(f)
land (39.2 acres within the LMNRA, 20.3 acres within the NHL, and 14.3 acres within the
TCP; see Figure 6-2). A major regulatory agency concern and potential worst-case impact
on recreational lands is the threat of a major hazardous materials spill on the new bridge,
which could impact thousands of acres of lake waters and shoreline within the LMNRA.
This alternative would not directly impact any recreational facility or resource located
within Section 4(f) land. During construction, the noise of construction and presence of
heavy equipment would temporarily lower the aesthetic experience for some visitors at the
dam and in the area; however, others would find the construction operation interesting.
Following construction and the subsequent diversion of traffic off the dam to the new
bridge, truck-derived noise and exhaust fumes would be removed from the dam, thereby
improving conditions for dam visitors. The long-term effect of this alternative will be to
improve the recreationists' access to Hoover Dam by reducing traffic congestion and to
make U.S. 93 a safer transportation facility. The new bridge could also become a
recreational attraction in itself because of its proximity to Hoover Dam.

6.4.1.2 Cultural and Historic Resources
Implementation of the Promontory Point Alternative would affect a total of nine historic
and cultural resource sites subject to protection under Section 4(f). These consist of Hoover
Dam (listed as an NHL and in the NRHP), a concrete diversion channel (a contributing
element to the NHL), a concrete retaining wall (a contributing element to the NHL), a
power transmission switchyard (a contributing element to the NHL), transmission towers
in Nevada, the Old Government Railroad grade, building foundations (near Nevada bridge
abutment), U.S. 93 segment in Arizona (a contributing element to the NHL), and the TCP.
The alternative crosses Lake Mead approximately 1,000 feet upstream from the dam and
takes 20.3 acres of right-of-way from the northern portion of the 330-acre NHL property.
This constitutes a permanent use of a portion of the historic property under Section 4(f).
The alternative also uses 14.3 acres of land from the TCP.

FHWA and the NPS have determined that construction of a bridge at the Promontory Point
crossing would adversely affect visitors' "first impression" historic views of the dam. These
views occur as motorists approach the dam on existing U.S. 93 from both Nevada and
Arizona. The dominance of the Promontory Point bridge would significantly detract from
the historic views of the dam, because the bridge would conflict with Hoover Dam at the
visitors' first opportunity to view it, a condition that could not be mitigated. In addition,
preliminary Reclamation consultation with the SHPOs in the early 1990s indicated that the
Promontory Point bridge alternative would be too close and would compete with the dam.
6-10 SCO/CHARTS. WPD/003672782
-------
CHAPTER 6 SECTION 4(F) EVALUATION
Table 6-1
Section 4(1) Impacts of the Hoover Dam Bypass Project
Resource
Promontory Point
Sugarloaf Mountain
Gold Strike Canyon
No Build-
Cultural Resources
Hoover Dam (NHL)

Dam-related historic
features eligible for
National Register"
TCP eligible for
National Register
Noise'
Recreation
Aesthetics
Section 4(f) Land
Adverse effect to historic visual
setting (nonmitigable)"
Adverse effect on seven
features

Adverse effect

No impact
Slight impact to boaters on Lake
Mead. Positive impact to
visitors at Hoover Dam

Impact to historic view of
Hoover Dam and Black Canyon

Would take 20.3 acres of NHL
land, 39.2 acres of LMNRA
land, and 14.3 acres of TCP for
74 total acres
Adverse effect to historic
visual setting (mitigable)"
Adverse effect on eight
features8

Adverse effect

No impact
Positive impact to visitors at
Hoover Dam
Impact to existing view of
Black Canyon

Would take 12.4 acres of
NHL land, 57.1 acres of
LMNRA land, and 22.3 acres
of TCP for 92 total acres
No adverse effect to historic
visual setting
Adverse effect on five features
Adverse effect (nonmitigable)

Substantial increase in noise
(>15 dBA) in upper canyon

Impacts on Gold Strike Canyon
Trail hikers due to loss of
access. -Positive impact to
visitors at Hoover Dam
Impact to existing views of
Black Canyon and Gold Strike
Canyon
Would take 0 acre of NHL land,
76.6 acres of LMNRA land, and
51 acres of TCP for 128 total
acres
(See footnote0)
No change
Impacts to Hoover Dam
location due to increased
traffic
No change
No change
No change
" No action is defined by the Council of Environmental Quality as either, "no change from current management practices" or "the proposed activity would
not take place." The No Build Alternative provides data for comparison purposes.
" FHWA and NPS determined the Promontory Point bridge would adversely affect the historic views of Hoover Dam while the Sugarloaf Mountain bridge
would not, and that this impact cannot be mitigated.
c The No Build Alternative could result in potential structural damage from accidents and hazardous spills and in continued modification of the dam and
its setting to improve traffic safety and access. Without long-range cultural resources planning, this alternative eventually may result in effects to the
historic values from which the dam derives its significance.
" See Section 3.5 for specific details on impacts to cultural resources in the project area.
9 FHWA conducted a supplemental historic resources survey of the preferred alternative and located six additional historic features associated with the
NHL; two of the eight adversely affected features only have the setting impacted.
' See Table 3-6 for specific details.
SCO/CHAPT6.WPD/003672782
6-11
-------
CHAPTER 6 SECTION 4(F) EVALUATION
This page intentionally left blank
6-12 SCO/CHAPT6.WPD/003672560 ]
-------
uxr MEW MVKMU. iKoaxnoNMta

ALTERNATIVE
PrwnortwyPeW
Sug*toflfAtouot»«
GoM SWw Canyon
UKEMEAOflMBOAWL
ReCAEATTOMAREA
SMfcROW
f*MMefc>3
2J.8
28.5
«.7
Aden ROW
(s*eNot»3)
17.4
30.9
S0.9
NHt
ACREAGE
20.3
(2.*
0.0
TCP
ACREAGE
14.3
223
51.0
ACREAGE
74
92
128
** «ns«hg Hwy. M, 200 It, on* ctflte of ===< ***» I

TbW xMftoawl ROW * 30.9 COM

£CCm2eM.1S.(H pubhi3lh1ina
FIGURE 6-2
SECTION 4(f)

PUBLIC RECREATION LANDS
HOOVER DAM BYPASS PROJECT
ENVIRONMENTAL IMPACT STATEMENT
-------
CHAPTER 6 SECTION 4(F) EVALUATION
This page intentionally left blank
6-14 SCO/CHAPT6.WPD/003672560 ]
-------
CHAPTER 6 SECTION 4(F) EVALUATION
As with the other two build alternatives, this alternative would enhance protection of the
physical features of Hoover Dam by removing trucks from the dam, thereby eliminating the
potential for hazardous material spills and large-vehicle collisions with dam facilities.

6.4.1.3 Noise
Five receptor sites were selected in human-use areas to determine current and predicted
noise impacts for this project: the Lakeview Point Overlook, the Nevada Intake Tower at the
dam, a raft launch concession below the dam, the hot springs located at the mouth of Gold
Strike Canyon, and a point along the Gold Strike Canyon Trail (Figure 3-1).

The closest receptor sites for Promontory Point Alternative are the Lakeview Point
Overlook (receptor R1/M1) and the Nevada Intake Tower (receptor R3/M3). Lakeview
Point Overlook would experience a future predicted noise level of 56 dBA; noise sources
consist primarily of U.S. 93. The Nevada Intake Tower is predicted to have a future noise
level of 74 dBA from traffic on U.S. 93 and the new bridge. The existing noise level at
R1/M1 is 50 dBA (from U.S. 93), and at R3/M3 it is 73 dBA (also from U.S. 93). The new
bridge would be located approximately 1,000 feet upstream of the dam. Most recreational
activity in this area is associated with Hoover Dam visitation. As with Sugarloaf Mountain
Alternative, most of the proposed alignment for Promontory Point falls within 2,000 feet of
existing U.S. 93. Hence, constructing the Promontory Point Alternative would not result in
significant increases in noise.

6.4.1.4 Aesthetics
Views of the Promontory Point Alternative would be unobstructed from locations on Lake
Mead up to 1.2 miles upstream of the dam. The new bridge would be visible from Hoover
Dam (which receives over 1 million visitors per year) and by aerial sightseers, thus
changing the landscape setting of Lake Mead from the dam and the air. As discussed in
Chapter 3, the visual quality of the view looking toward the dam from a boat on the lake
would be most affected by the steel truss rib through arch bridge design on this alignment.
The vividness (memorability of the existing landscape components) would be compromised
by the introduction of the bridge structure. In addition, the intacmess of the landscape and
the unity (visual harmony between landscape elements) would be affected by the size and
prominence of the form, contrasting lines, and textural differences between the proposed
bridge and the existing landscape.

Views of Lake Mead from the dam crest, of the dam crest itself, and of Black Canyon from
Lake Mead would be dominated by the Promontory Point bridge. The adverse visual effect
could not be mitigated due to the obtrusive nature of the bridge and the protrusion of the
structure, regardless of type, above the horizon.

6.4.1.5 Access
The Promontory Point Alternative would improve access to the HDNHL interpretive
facilities by diverting all but visitor traffic off the existing, highly congested, two-lane dam
crossing and approaches and onto a new four-lane U.S. 93 bridge located approximately
1,000 feet upstream from the dam.
SCO/CHAPT6.WPD/003672560 6-15
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.4.2 Sugarloaf Mountain Alternative (Preferred Alternative)

The Section 4(f) properties and/or resource values were identified and assessed for
potential impact by the Sugarloaf Mountain Alternative. The following summarizes the
results of that effort. (A more detailed description of these analyses and conclusions can be
found in Chapter 3.)

6.4.2.1 Park Land and Recreation
As stated previously, the Sugarloaf Mountain Alternative would permanently use 92 acres
of Section 4(f) land (57.1 acres within the LMNRA, 12.4 acres within the HDNHL, and
22.3 acres within the TCP) (Figure 6-2). Much of this alternative traverses or is adjacent to
areas of existing disturbance (e.g., power lines and related facilities). The Sugarloaf
Mountain Alternative would not directly impact any recreational facility or resource located
within Section 4(f) land. During construction, the noise of construction and presence of
heavy equipment would temporarily lower the aesthetic experience for some visitors at the
dam and in the area; however, others would find the construction operation interesting.
Undesignated trail-use regulations within the LMNRA might need to be adjusted to
accommodate construction activities, but these inconveniences would be minor and
relatively short term. Following construction and the subsequent diversion of traffic off the
dam to tire new bridge, truck-derived noise and exhaust fumes would be removed from the
dam, thereby improving conditions for dam visitors. The long-term effects of this
alternative would be to improve the recreationists' access to Hoover Dam by reducing
traffic congestion and to make U.S. 93 a safer transportation facility. The new bridge could
also become a recreational attraction in itself because of its proximity to Hoover Dam.

In summary, the Sugarloaf Mountain Alternative would not significantly change the
remaining portions of Section 4(f) lands in relation to noise or recreation qualities (see
Chapter 3 for details). Construction activities would disrupt traffic flow and have some
adverse effects on noise, visual, and aesthetics qualities, but these effects would be
relatively short term. These activities would be closely monitored by and coordinated with
Reclamation and NFS to minimize adverse impacts and activities.

6.4.2.2 Cultural and Historic Resources
Implementation of the Sugarloaf Mountain Alternative would affect 10 historic and cultural
sites. These resources are the HDNHL, a power transmission switchyard (a contributing
element to the NHL), the Old Government Railroad grade, transmission towers in Nevada,
stone gates, U.S. 93 switchback (a contributing element to the NHL), Kingman Switchyard
in Arizona, transmission towers in Arizona, the Old U.S. 93 segment in Arizona (a
contributing element to the NHL), and the TCP. The alternative crosses the Colorado River
gorge 1,500 feet downstream from the dam and takes approximately 12.4 acres of
right-of-way from the 330-acre NHL property in its southwest corner. This constitutes a
permanent use of a portion of the historic property under Section 4(f). The alternative also
uses 22.3 acres of land from the TCP.

The Sugarloaf Mountain bridge would not detract from the "first impression" historic views
as visitors see the dam from the Arizona and Nevada approaches because it is not visible
due to the existing roadway alignment that presents a direct view of the dam and Lake
Mead. The Sugarloaf Mountain Alternative would enhance protection of the physical
features of Hoover Dam by eliminating the potential for hazardous material spills and
large-vehicle collisions with dam facilities.

6-16 SCO/CHAPT6.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION
Archaeological site NV:DD:14:21 contains a cobble deposit with associated lithic reduction
debris located on the lower slope of Sugarloaf Mountain. It is located within and
contributes to the National Register eligibility of the larger TCP, and would be impacted by
the bypass construction. Specifically, the site contains "doctor rocks" identified by tribal
elders as used for healing and other ceremonial purposes.

Impacts to the Gold Strike Canyon and Sugarloaf Mountain TCP include land disturbance
and changes in viewshed and noise. However, the land traversed by this alternative and
viewsheds from prominent TCP locations have been significantly altered by construction of
the dam and associated facilities. Furthermore, the Native American tribal elders
interviewed in the ethnographic study stated that the integrity of the Sugarloaf TCP has not
been diminished by the superficial impacts of traffic, construction of the treatment pond, or
the presence of power lines.

6.4.2.3 Noise
The closest noise receptor site to the Sugarloaf Mountain Alternative is the raft launch site
(receptor R2/M2), where the noise generated by traffic on the new bridge would be
57 decibels. The Nevada Intake Tower (R3/M3), which is about 2,030 feet from the
proposed Sugarloaf bridge, would experience a predicted future noise .level of about
74 decibels; noise sources consist of the new bridge, the existing dam crossing, and the
Visitor's Center. Although this exceeds the federal noise abatement criterion, it represents a
noise level decrease of approximately 3 dBA from the future no build predicted level of
77 dBA and an increase above the existing noise level of only 1 dBA. The existing noise
level at R2/M2 is 52 dBA (from sound of river), and at R3/M3 it is 73 dBA (from existing
traffic on U.S. 93). The future reduction is due to traffic being diverted to the new crossing
(approximately 1,500 feet downstream from the dam).

The predicted 56 dBA noise level at the Lakeview Point Overlook (R1/M1) would be the
same as the Promontory Point Alternative, given that these bypass alternatives are on
essentially the same alignment near the overlook. Most of the proposed Sugarloaf
Mountain Alternative falls within 2,000 feet of the existing U.S. 93 alignment; therefore, no
significant increases in noise pollution would result along the entire length of the proposed
highway.

6.4.2.4 Aesthetics
Views of the Sugarloaf Mountain Alternative would be unobstructed from Hoover Dam,
except for the transmission towers and rock outcroppings in the foreground, and from the
raft launch site 0.5 mile downstream of the dam. In addition, the new bridge would be
visible by aerial sightseers, thus changing the aerial view of the dam and canyon. As
discussed in Chapter 3, the visual quality of the view looking downstream from the eastern
side of Hoover Dam would be most affected by the concrete cable-stayed bridge design.
The vividness (memorability of the existing landscape components) of the view would be
degraded by the presence and closeness of the bridge structure. In addition, the intactness
and unity (visual harmony between landscape elements) of the view would be affected by
the size and prominence of the bridge form; the vertical, horizontal, and diagonal lines; and
the textural differences between the proposed bridge and the existing landscape.

The Sugarloaf Mountain bridge would be visible looking toward Black Canyon from Lake
Mead and from the dam crest. However, certain bridge types would tend to blend into the
surroundings due to continuity between the horizontal deck and canyon rim elements and
the fact that elements of the bridge would not significantly protrude above the horizon line.
SCO/CHAPT6.WPD/003672560
-------
CHAPTER 6 SECTION 4(F) EVALUATION
(See Figure 3-10.) Other bridge types whose towers and cable supports rise above the
horizon line include elements that are similar in appearance to the existing power lines and
transmission structures. Final bridge type will be based on input from a Design Advisory
Panel, formed by the Programmatic Agreement, to mitigate adverse historic and visual
impacts in concert with other major project factors.

6.4.2.5 Access
The Sugarloaf Mountain Alternative would improve access to the HDNHL interpretive
facilities by diverting all but visitor traffic off the existing, highly congested, two-lane dam
crossing and approaches and onto a new four-lane U.S. 93 bridge located 1,500 feet
downstream from the dam.

6.4.3 Gold Strike Canyon Alternative

The Section 4(f) properties and/or resource values were identified and assessed for
potential impact by the Gold Strike Canyon Alternative. The following summarizes the
results of this effort. (A more detailed description of these analyses and conclusions can be
found in Chapter 3.)

6.4.3.1 Park Land and Recreation
The Gold Strike Canyon Alternative would permanently use a total of 128 acres of
Section 4(f) recreation land (76.6 acres within the LMNRA and 51 acres within the TCP)
(Figure 6-2). This alternative would result in negative impacts to Gold Strike Canyon
hikers. Although the Gold Strike Canyon trail is not an official NPS-designated trail,
numerous hikers use it as a trail leading to the hot springs located at the lower end of Gold
Strike Canyon. The trail would be closed during the 5- to 6-year construction period. The
proposed highway for this alternative would pass over the trail at several locations, and
traffic from the new highway would create new noise pollution along nearly the whole
length of the trail. (See the following discussion of noise, aesthetics, and access impacts on
the Gold Strike Canyon Trail.)

Within Gold Strike Canyon, the roadway would be constructed primarily on elevated
structures where it would overlay and cross the popular Gold Strike Canyon Trail from
near the trailhead located just south of U.S. 93 (approximately 0.5 mile south of the
Lakeview Point turnoff) to within about 0.5 mile of the river, a total distance of
approximately 1 mile. The length of the trail from the trailhead to the HDRA Boundary,
approximately 0.75 mile along the proposed highway, is within the LMNRA and is under
Section 4(f) protection. The HDRA is excluded from the LMNRA for the protection and
security of the dam powerplant and associated facilities.

Following construction and the subsequent diversion of traffic off the dam to the new
bridge, truck-derived noise and exhaust fumes would be removed from the dam, thereby
improving conditions for dam visitors. The long-term effect of this alternative will be to
improve the recreationists' access to Hoover Dam by reducing traffic congestion and to
make U.S. 93 a safer transportation facility.

6.4.3.2 Cultural and Historic Resources
Implementation of the Gold Strike Canyon Alternative would only indirectly affect Hoover
Dam through a slight change to the visual historic setting. Opinions of the Nevada and
Arizona SHPOs and the NFS were that construction of a bridge at the Gold Strike crossing
6-18 SCO/CHAPT6.WPD/003672560}
-------
CHAPTER 6 SECTION 4(F) EVALUATION

location would have no adverse effect on the historic visual setting of the landmark.2 The
Gold Strike Canyon Alternative would also affect six other historic and cultural sites. These
resources are the wooden ladders site (a contributing element to the NHL), Nevada waste
tailings (a contributing element to the NHL), Arizona waste tailings (a contributing element
to the NHL), construction road and test borings (contributing elements to the NHL), the Old
U.S. 93 segment in Arizona (a contributing element to the NHL), and the TCP. As with the
other two alternatives, the Gold Strike Canyon Alternative would enhance protection of the
physical features of Hoover Dam by removing trucks from the dam, thereby eliminating the
potential for hazardous material spills and large vehicle collisions with dam facilities.

6.4.3.3 Noise
The Gold Strike Canyon Alternative is the farthest from existing traffic-generated noise
pollution associated with U.S. 93. Implementing this alternative would result in a
permanent increase of approximately 26 dBA at the Gold Strike Canyon Trail site from
traffic on the new U.S. 93 alignment, for a total of 65 dBA (the present ambient noise level is
approximately 39 dBA). This would be below the 67-dBA federal noise abatement criterion;
however, it would constitute a substantial increase (more than 15 dBA) under NDOT and
ADOT noise abatement policies. Therefore, the projected noise level increase attributable to
the project would substantially impair the use and enjoyment of the Gold Strike Canyon
Trail by hikers. With mitigation (see below), the projected noise level increase can be
reduced to 20 dBA above existing conditions, for a total of 59 dBA.

There is no predicted increase in the existing ambient noise level of 60 dBA at the Gold
Strike Canyon Hot Springs from this alternative realignment of U.S. 93. Existing noise
levels at the hot springs are caused from the sound of rushing water around the hot springs.
The hot springs site would be shielded from future traffic-associated noise from the Gold
Strike Canyon Alternative by intervening cliffs. Due to the serene and quiet nature of the
previously undisturbed area, mitigation must be considered in those areas that would be
affected by excessive noise levels (increases greater than 15 dBA above the existing ambient
levels). Noise level decreases of approximately 3 dBA are predicted at both the Nevada
Intake Tower and at Lakeview Point (from predicted future no-build levels of 77 dBA and
54 dBA, respectively) due to traffic being diverted to the new crossing location
approximately 1 mile downstream.

6.4.3.4 Aesthetics
Views of the Gold Strike Canyon Alternative would be completely obstructed from Hoover
Dam, the Arizona Overlook, and Lake Mead. The new bridge would be visible from the
raft put-in 0.5 mile downstream of Hoover Dam and by aerial sightseers. As discussed in
Chapter 3, the new Colorado River bridge would substantially change the landscape setting
of Gold Strike Canyon as seen from the hiking trail and hot springs. From the view of Black
Canyon looking downstream from the raft launch location, the concrete deck arch bridge
design would have the most pronounced visual affect. Because the concrete forms on this
bridge are larger than in the steel deck arch bridge, the visual impact from this bridge
design is greater than for the steel deck arch bridge. With either bridge design, the
vividness of the landscape components would not be adversely affected by the bridge
2The Advisory Council on Historic Preservation concurred with these preliminary opinions in a
December 11,1991 letter stating, "We agree that the construction of the bridge at Gold Strike Canyon
appears to be the alternative which is least likely to have an adverse effect on the Hoover Dam
National Historic Landmark."

SCO/CHAPT6.WPD/003672560 6-19
-------
CHAPTER 6 SECTION 4(F) EVALUATION
structure; however, the intactness and unity of the view would be compromised by the size
and prominence of the form and contrasting lines.

The Gold Strike Canyon Trail is used by visitors to hike down through the canyon to the
river and the hot springs. Because of the heavy use of the hot springs area, the NFS has
provided a portable toilet and trash receptacles at the mouth of the canyon.

At several locations in the canyon the highway alignment would cross over or lay directly
above the canyon bottom and hiking trail. Construction of primarily highway bridges and
retaining walls is required in lieu of fills through Gold Strike Canyon because fill slopes
would interfere with drainage flows and drastically alter the canyon bottom for hiking.
Views by recreationists using the hiking trail or hot springs would be adversely affected by
this alternative, regardless of the bridge design that is selected.

6.4.3.5 Access
The Gold Strike Canyon Alternative would improve access to the HDNHL interpretive
facilities by diverting all but visitor traffic off the existing, highly congested, two-lane dam
crossing and approaches and onto a new four-lane U.S. 93 bridge located about 1 mile
downstream from Hoover Dam.

During the construction period for this alternative (5 to 6 years), the Gold Strike Canyon
trail would be closed from U.S. 93. Recreation activities within this area would be
prohibited. Consequently, hiking access along this popular public parkland trail through
Gold Strike Canyon to the river and hot spring pools would be blocked for years during
construction of this highway alternative. Furthermore, the natural views and rugged
appeal of this pristine canyon setting would be permanently replaced with concrete
columns and overhead bridges crisscrossing the canyon trail for most of its length. This
condition would substantially diminish the utility of this natural trail access to the river.

6.5 Avoidance Alternatives

Because of the unique situation of Section 4(f) lands being continuous from 40 miles north
to 60 miles south of the existing corridor, it is not possible to avoid these lands and still
maintain the service that existing U.S. 93 provides for this area of the Southwest
(Figure 6-1). Consequently, there are no reasonable alternative routes that meet the project
purpose and need, and avoid the use of Section 4(f) lands. The following avoidance
alternatives are fully described and compared in Chapter 2.

A total of four alternatives would avoid the use of Section 4(f) lands:

• No Build Alternative

• Restricting motorized traffic from crossing Hoover Dam
- Option for restricting truck traffic only
- Option for restricting all traffic

• Traffic Systems Management

• U.S. Highway 95/1-40
6-20 SCO/CHAPT6.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.5.1 No Build Alternative
The No Build Alternative would consist of no action being taken. No bypass of Hoover
Dam would be developed, no change in the current highway configuration would occur,
and no other structural or nonstructural improvements would be developed on U.S. 93 near
Hoover Dam. Existing hairpin curves, inadequate sight distance, narrow dam crest
roadway, and steep grades on U.S. 93 in the vicinity of Hoover Dam would remain
unchanged. No direct construction costs would result from this alternative.

However, an increase in operations and maintenance costs is foreseeable because of the
increased traffic and congestion on and near the dam. The public would also incur added
costs because of more frequent traffic delays and accidents.

The No Build Alternative would not meet the purpose and need of the project as it would
not remove a major bottleneck to regional commerce by increasing the capacity of U.S. 93
near the dam to improve through-vehicle and truck traffic, nor would it substantially
reduce traffic congestion and accidents at the dam and approaches. It would not minimize
out-of- direction travel during periods of significant delays at the dam crossing or reduce
vehicle hours of travel and improve travel speeds. It may increase the potential for a
catastrophic spill of hazardous materials with increasing automobile and truck traffic
volumes on the dam and approaches. The risks to innocent bystanders, property damage to
the dam and its facilities, contamination of the waters of Lake Mead or the Colorado River,
and interruption of the power and water supply for people in the Southwest would remain
or increase.

This alternative would not minimize impacts on recreation resources and tourists. It would
not reduce the potential for pedestrian-vehicular accidents on the crest of the dam and on
the Nevada and Arizona approaches to the dam. The increased traffic volumes, ranging
from a forecasted 21,100 AADT in 2017 to 26,000 AADT in 2027 on Hoover Dam under no
build versus 4,700 AADT in 2017 to 6,100 AADT in 2027 under the bypass alternatives,
traveling at slower speeds would contribute to decreased air quality in the vicinity of
Hoover Dam (see Traffic Analysis, Appendix A). There would also be increased congestion
for tourists at Hoover Dam and parts of the LMNRA.

6.5.2 Restricting Motorized Traffic from Crossing Hoover Dam

The possibility of restricting traffic from using Hoover Dam to cross the Colorado River was
examined with two options:

• Restricting truck traffic (through restriction on specific classifications of vehicles), which
results in diversion to alternate routes, but leaves Hoover Dam open to automobile
traffic; and

• Restricting all traffic, which results in diversion of all traffic to alternate routes and thus
closes Hoover Dam to all motorized vehicles.

At the present time, Hoover Dam is the only Colorado River crossing in the general vicinity
of Las Vegas, Nevada. The closest alternate crossings are at Lee's Ferry, 250 miles upstream
of Hoover Dam; and at Davis Dam or Laughlin Bridge, 67 and 70 miles downstream,
respectively. As a result, the river crossing on Hoover Dam is very important to both the
commercial trucking industry and other travelers on U.S. 93.
SCO/CHAPT6.WPD/003672560 6-21
-------
CHAPTER 6 SECTION 4(F) EVALUATION
In 1997, the AADT on Hoover Dam was 11,500 vehicles (13,200 vehicles on the Nevada
side). Excluding commercial busses, approximately 18 percent of these daily vehicles were
commercial trucks. Closure of the dam to traffic would likely result in a diversion of these
vehicles to State Route (SR) 163 and U.S. 95 in Nevada and SR 68 in Arizona (the Laughlin-
Bullhead City Alternative). These routes would add 23 miles to the trip from Kingman,
Arizona, to Las Vegas, Nevada. Another possible route from Kingman to Las Vegas would
be Interstate 40 (1-40) to Needles, California, and then north on U.S. 95 to Las Vegas.
However, vehicles using these routes would travel 50 more miles than if they used SR 163
in Nevada as the alternate route. In either instance, U.S. 95 south of Las Vegas would
experience a dramatic increase in traffic.

This alternative (with two options) for traffic restriction was eliminated because:

1. It does not fulfill the designated functional requirements of U.S. 93 as a principal arterial
highway.

2. It would eliminate a major segment of a primary norm-south U.S. highway.

3. The traffic congestion and safety considerations would merely be shifted from Hoover
Dam to other locations.

4. Major sections of the alternate routes were not designed and built to sustain the heavy
loads and volume of vehicles that would be diverted from Hoover Dam, resulting in a
shortened life for those highways.

5. In addition to the extra travel distance, alternative transportation routes have greater
elevation changes, resulting in both increased travel time and operating cost for
commercial carriers and the general traveling public (see Appendix B).

6.5.3 Traffic Systems Management

A Traffic Systems Management (TSM) Study was completed in January 1992 to determine
whether or not a low cost solution exists for the current and projected traffic congestion,
pedestrians, and vehicle safety problems at the present crossing. Typically, TSM addresses
signing and signalization, turn lanes and traffic channelization, vehicle turn-outs, vehicular
access and parking controls, and pedestrian channelization and barriers.

The TSM Study concluded that some minor improvements in traffic flow could result from
low cost changes in operational conditions; specifically: (1) existing crosswalks should be
widened and supplemental signing added to better concentrate pedestrian crossings, which
would minimize accident potential and improve overall traffic flow on the dam crest; and
(2) the immediate approaches to Hoover Dam should be signed to indicate the location of
visitor parking lots, which was done with construction of the Visitor's Center. The study
concluded this would alleviate some of the traffic congestion that results from visitor
confusion regarding parking lot locations.

However, because of the existing horizontal curves, roadway width on the dam, and
pedestrian volumes, no significant improvements could be realized without provision of an
alternate route. The existing traffic conditions will only deteriorate with future growth of
the traffic volumes. The existing geometry of the highway approaching and over Hoover
Dam is a source of difficulty for semitrailer trucks in making the necessary maneuvers
around the hairpin curves and the 90-degree curve. This condition will continue to result in
6-22 . SCO/CHAPT6.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION

accidents and extensive delays to through traffic. The study recommended that a new
four-lane route should be provided.

Therefore, this alternative was eliminated from further consideration because it could not
meet the purpose and need of the project. Since this alternative would only involve
modifications to the existing route, it would not use additional Section 4(f) resources;
however, the TSM Study concluded that only minor improvements in traffic flow could
result from changes in operational conditions. This alternative was eliminated because:

1. No significant improvements to traffic flow would be realized due to the existing
geometry of the highway approaching and crossing Hoover Dam, including the
inadequate horizontal curves and highway width on the dam, and due to the high
traffic and pedestrian volumes.

2. It does not fulfill the designated functional requirements of U.S. 93 as a principal arterial
highway.

3. The vehicle-pedestrian, vehicle-vehicle, and vehicle-sheep conflicts would not be
changed.

6.5.4 U.S. 95/1-40

This alternative to U.S. 93 improves the existing route between Boulder City and Kingman
via Needles, California. Approximately 56 miles of U.S. 95 in Nevada and 13 miles of
U.S. 95 in California would be widened to four lanes. No improvements to existing 1-40 and
its crossing of the Colorado River south of Needles are necessary.

The U.S. 95/1-40 Alternative does not meet the project purpose and need because it would
not substantially eliminate roadway deficiencies and reduce traffic congestion on U.S. 93 at
Hoover Dam and dam approaches, eliminate through traffic from the dam, enhance public
safety, or protect Hoover Dam and its visitors. The U.S. 95/1-40 Alternative was eliminated
because motorists would avoid driving the additional 70 miles by continuing to use the
Hoover Dam crossing. Therefore, meeting the objectives of enhanced safety and reduced
congestion on U.S. 93 at the dam would not be achieved.

6.6 Justification for Use of Section 4(f) Land

6.6.1 Evaluation of Potential Avoidance Alternatives

The basis for concluding that there are no feasible and prudent alternatives to the use of
Section 4(f) land must demonstrate that:

• There are unique problems or unusual factors associated with the alternatives that avoid
Section 4(f) lands, or

• The cost, social, economic, and environmental impacts, or community disruption from
such alternatives reach extraordinary magnitudes.

The geographic shape of LMNRA and the location of existing U.S. 93 (i.e., a narrow strip of
area extending approximately 60 miles south of the existing road corridor and a variable
width strip of area extending approximately 40 miles east of the existing corridor, see
Figure 6-1) creates a unique problem regarding total avoidance of Section 4(f) land.
SCO/CHAPT6.WPD/003672560 6-23
-------
CHAPTER 6 SECTION 4(F) EVALUATION
| 6.6.1.1 U.S.95/I-40
Any alternative that would route through traffic around the southern end of the LMNRA
would add, at a minimum, approximately 25 miles of out-of-direction travel to the mileage
currently traveled by existing U.S. 93 motorists. Based on analysis of the Laughlin-Bullhead
City Alternative (LBA), which traverses the extreme southern end of LMNRA, this
represents an additional $1.4 billion dollars in total 20-year costs (see Appendix B). These
additional total user costs are an increase of approximately 10 percent over the build
alternatives studied in detail and result in a negative benefit to cost ratio. Thus, the
U.S. 95/1-40 alternative that passes far to the south of LMNRA and adds approximately
70-miles to the trip length is considered to be unfeasible with respect to engineering
economics and imprudent regarding the increased travel time, user costs, and
environmental impacts.

| 6.6.1.2 Restricting Traffic from Hoover Dam
| This alternative was determined to be unfeasible and imprudent primarily because:

• It does not fulfill the designated functional requirements of U.S. 93 as a principle arterial
highway

| • It would eliminate a major segment of a primary north-south U.S. highway

| Additional reasons are explained in section 6.5.2.

| 6.6.2 Purpose and Need

The U.S. 95/1-40 Alternative, passing to the south of LMNRA, and the No Build Alternative
do not meet the project purpose and need because a substantial portion of the through
traffic (all for the no build) would continue to use existing U.S. 93 due to the 70-mile trip
length increase from Kingman, Arizona to Las Vegas, Nevada. Therefore,
pedestrian-vehicle accident rates, congested bottleneck conditions, substandard approaches,
and travel time would not be improved.

The Traffic Systems Management alternative would not significantly improve traffic flow
across Hoover Dam, minimize the potential for pedestrian-vehicle accidents, improve
protection of the dam facility, or improve operation and maintenance conditions, and
therefore it does not meet the project purpose and need.

| 6.6.3 Least Harm Alternative

When there are no feasible and prudent alternatives that avoid the use of Section 4(f) land,
the final Section 4(f) evaluation must demonstrate that the preferred alternative is a feasible
and prudent alternative with the least-harm on the Section 4(f) resources after considering
mitigation. To make a least harm determination, the net impact on Section 4(f) land may
consider not only size of land used, but also the:

• Location of the portion used
• Severity of the portion used
• Function of the portion used
6-24 SCO/CHAPT6.WPD/003672560 ]
-------
CHAPTER 6 SECTION 4(F) EVALUATION

The remainder of this section describes the logic used to determine the least harm
alternative. Two build alternatives with relatively lower Section 4(f) use are the
Laughlin-Bullhead City and Modifications to Hoover Dam alternatives.

6.6.3.1 Modifications to Hoover Dam.
The two modification alternatives, widening the crest and elevating the highway structure,
would not:

• Minimize the potential for pedestrian-vehicle accidents
• Improve protection of the dam facility
• Improve operation and maintenance conditions

Therefore, mese alternatives do not meet the project purpose and need. In addition, the two
modification alternatives would result in direct adverse physical alteration to the HDNHL
in terms of its original design, setting, materials, and workmanship.

6.6.3.2 Laughlin-Bullhead City
The LB A does not meet the project purpose and need; would not reduce travel time; would
have adverse impacts on public safety, sensitive wildlife species, and air quality; would not
protect the HDNHL; and would not fully address long-term traffic issues on Hoover Dam.

Further, based on the LBA study in Appendix B an additional $1.4 billion dollars in total
20-year costs would be accrued. These additional total user costs are an increase of
approximately 10 percent over the build alternatives studied in detail and result in a
negative benefit to cost ratio. Thus, this alternative is considered to be unfeasible with
respect to engineering economics and imprudent regarding the increased travel time, user
costs, and environmental impacts.

6.6.3.3 Alternatives Eliminated Based on Acreage and Quality Impacts
Based on Section 4(f) acreage impact considerations the following initial alternatives can be
readily eliminated.

Gold Strike Canyon (128 acres)
Boulder City North (145 acres)
Boulder City South (165 acres)
Boulder City South Option (135 acres)
Willow Beach North (405 acres)
Willow Beach South (575 acres)
Nelson (491 acres)
Cottonwood (436 acres)
Temple Bar (818 acres)

In addition, the LMNRA Section 4(f) acreage traversed by these alternatives is essentially
undisturbed.
SCO/CHAPT6.WPD/003672560 6-25
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.6.3.4 Determination of Least-Harm Alternative
4
Based on the above discussion the remaining two alternatives are Sugarloaf Mountain and
Promontory Point. Promontory Point Alternative uses approximately 74 acres of
Section 4(f) land. Sugarloaf Mountain Alternative uses approximately 92 acres. However,
much of Sugarloaf Mountain Alternative traverses or is adjacent to areas of existing
disturbance (e.g., power lines and related facilities) that detract from recreational and scenic
qualities.

The Sugarloaf Mountain Alternative uses approximately 58 acres of LMNRA, 12 acres of the
HDNHL and 22 acres of the TCP. The Promontory Point Alternative uses approximately
40 acres of LMNRA, 20 acres of the HDNHL and 14 acres of the TCP.

As discussed earlier in this section, least-harm considerations are not always a function of
minimizing acreage take. Other important factors such as location, severity and function of
the portion taken also may play a role in the decision-making process.

Three primary Section 4(f) activities or features are affected by the Sugarloaf Mountain and
Promontory Point Alternatives:

• Recreational opportunities associated with LMNRA
• Recreational opportunities associated with HDNHL
• The historic and cultural values of HDNHL and TCP

Both alternatives improve recreational opportunities at the dam and in the LMNRA by
reducing congestion, vehicle-pedestrian conflicts, and environmental impacts associated
with truck traffic. Neither alternative permanently restricts access to recreational sites
currently in use or planned for use. Neither alternative results in perceptible changes in
noise pollution.

Both alternatives cross waters of the Colorado River. However, during the comment period
on the DEIS, there was strong public concern regarding the potential for a hazardous
material spill in Lake Mead from the Promontory Point bridge. Furthermore, the resource
and regulatory agencies, with the exception of the SHPOs who preferred Gold Strike
Canyon during early reviews for its lack of visibility from the HDNHL, unanimously
supported the Sugarloaf Mountain Alternative due to least impact to wildlife, wildlife
habitat, water quality, and jurisdictional waters of the U.S.

The Sugarloaf Mountain Alternative would not impact views of the dam as motorists
approach from Arizona or Nevada. Conversely, the Promontory Point Alternative would
be directly visible and would detract from the "first impression" historic views of the dam.

Both alternatives would adversely impact the scenic views from the dam crest and Lake
Mead. However, the Sugarloaf Mountain Alternative could be blended into the landscape
more readily than the Promontory Point Alternative. This is because (1) the Sugarloaf
Mountain Alternative deck structure would form a fairly contiguous horizontal line with
the canyon rim, (2) the structure would not significantly protrude above the horizon line
when viewed from the dam crest, and (3) the structure would not protrude above the
horizon line when viewed from Lake Mead. Conversely, the Promontory Point Alternative
would be obtrusive and protrude above the strong horizontal component of Lake Mead
regardless of bridge type.
6-26 SCQ/CHAPT6.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION

Both alternatives would affect the TCP. Both alternatives would be located in previously
disturbed portions of the TCP. The Promontory Point Alternative would follow the
northern boundary of the TCP along existing U.S. 93, whereas the Sugarloaf Mountain
Alternative would traverse a portion of the TCP. Therefore, the Promontory Point
Alternative would create less disturbance from a location standpoint. However, the
Sugarloaf Mountain Alternative would traverse the southern boundary of the existing
disturbed area, and the tribal elders interviewed stated that the integrity of the Sugarloaf
TCP has not been diminished by existing disturbance. In addition, impacts due to land
disturbance, visual changes, and noise would be mitigated through continuing consultation
with Native American tribes and by Native American involvement in the Design Advisory
Panel, formed by the Programmatic Agreement.

Therefore, the Sugarloaf Mountain Alternative has been determined to be the I
harm-minimizing alternative based on the following factors: I

• Strong public concern regarding hazardous materials spills in Lake Mead from the I
Promontory Point Alternative I

• Resource and regulatory agency support for Sugarloaf Mountain due to least impact to I
wildlife, wildlife habitat, and water quality I

• No effect on the "first impression" historic views of Hoover Dam |

• Ability to more readily blend Sugarloaf Mountain Alternative into the landscape |

• Sugarloaf Mountain Alternative traverses the National Register-eligible TCP in an area I
of extensive disturbance I

• Ability to minimize and mitigate impacts through continuing consultation and Native I
American participation on the Design Advisory Panel |

6.7 Measures to Minimize Harm

Following is a description of the measures that will be implemented in an effort to minimize
harm to Section 4(f) resources.

6.7.1 Recreation Resources

During the 5- to 6-year construction period for this project, certain recreation activity areas
would be designated as construction safety zones and recreation would be limited, or in
other places it would be eliminated entirely. Specifically during blasting operations, short
periods would occur when recreation access to affected areas must be prohibited for
protection of the public. Trail-use regulations within the LMNRA may need to be adjusted
to accommodate construction activities and to assure the safety of trail users. Scheduling of
these activities would be closely coordinated with the NPS and Reclamation, and there
would be ongoing public information provided.

Bicyclists and pedestrians would be prohibited from using the new bridge on any of the
bypass alignments. However, the existing crossing would be maintained on the roadway
across Hoover Dam.
SCO/CHAPT6.WPD/003672560 6-27
-------
CHAPTER 6 SECTION 4(F) EVALUATION
Construction safety practices would require that nets be used under the work area during
construction to protect areas below the bridges from falling debris, tools, equipment, or
building materials.

6.7.2 Aesthetics

Cuts, fills, and other construction activities would be performed so as to minimize impact to
scenic values, especially in undeveloped areas like Gold Strike Canyon. Mitigation
techniques would include rough cuts, feathering cut/natural environmental interfaces, use
of artificial desert varnish on rock cuts to match adjacent natural colors, colored concrete,
and other state-of-the-art methods (see Chapter 3). Care would be taken to remove all
construction debris and other trash from the site as construction is completed.

Excavated topsoil would be stored during construction and replaced on appropriate
disturbed areas outside the highway shoulders after construction to aid in re-establishing
desert vegetation. Cactus, yucca, and candidate plant species would be removed and
replanted, or reseeded in consultation with the NFS. The Programmatic Agreement for
historic and cultural properties also specifies that Corridor Design Criteria must be
developed for aesthetic consistency of major structural, roadway, and earthwork elements
of the bypass.

Specific mitigation measures for the three bypass alternatives, as developed in the EIS
Visual Resources Analysis, are as follows:

6.7.2.1 Promontory Point Alternative
In June 2000, FHWA applied the criteria of adverse effect (under 36 CFR 800.5) and
determined in consultation with the Nevada and Arizona SHPOs that the Promontory Point
Alternative would have an adverse effect on the Hoover Dam NHL because the bypass
project would introduce visual elements that diminish the integrity of the significant
historic features and setting of the property. Furthermore, FHWA and NFS concluded that
the new Promontory Point bridge would adversely affect visitors' historic views of the dam
from U.S. 93 in both Nevada and Arizona, and this could not be mitigated. Preliminary
opinions of the Nevada and Arizona SHPOs were that the adverse visual effect of the
Promontory Point Alternative could not be mitigated.

However, as documented in Chapter 3, impacts on visual resources from the steel truss rib
through arch bridge could be lessened by coloring the steel to blend with the surrounding
environment.

For a concrete cable-stayed bridge, to reduce the visibility of the pillars on the bridge, the
concrete should be tinted with nonglare colors that blend with the surrounding
environment. In addition, the cuts for the roadway approaches should be engineered to
minimize impacts on visual resources. Any slope protection should be tinted to blend with
the surrounding landscape.

For a suspension bridge, to reduce the impacts on visual resources from the bridge, the
concrete pillars should be tinted with nonglare colors that blend with the surrounding
environment. In addition, the roadway cuts for the roadway approaches should be
engineered to minimize impacts on visual resources. Any slope protection should be tinted
to blend with the surrounding landscape.
6-28 SCO/CHARTS.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION
6.7.2.2 Sugarioaf Mountain Alternative (Preferred Alternative)
FHWA also determined in consultation with the Nevada and Arizona SHPOs that the
Sugarioaf Mountain Alternative would have an adverse effect on the NHL because the
bypass project would introduce visual elements that diminish the integrity of the significant
historic features and setting. However, FHWA and NFS concluded that the preferred
alternative would not detract from the historic views of the dam as would the Promontory
Point Alternative. Measures to minimize the aesthetic/visual impact on the historic setting
were developed in consultation with the SHPOs (see Section 6.7.3). Preliminary opinions of
the Nevada and Arizona SHPOs were that the adverse effect of the Sugarioaf Mountain
Alternative could be mitigated through design features.

Impacts on visual resources from a concrete cable-stayed bridge for the Sugarioaf Mountain
Alternative could be reduced by using colored concrete or painting the bridge using a
nonglare color that blends with the surrounding environment. However, the closeness of
the bridge to the dam would still result in the bridge dominating the downstream view
from the dam.

6.7.2.3 Gold Strike Canyon Alternative
Impacts on visual resources from either the concrete deck arch bridge or the steel deck arch
bridge would be reduced by coloring the concrete or steel so that the bridge blends more
effectively with the surrounding environment. This measure would reduce the visual
impact perceived by the hikers, hot spring users, rafters, and other river users near the
proposed alignment. No impact on views from either Lake Mead or Hoover Dam would be
expected from this alternative.

6.7.3 Cultural and Historic Resources

Mitigation measures currently identified for the TCP have resulted from the ongoing
government-to-government consultation meetings among FHWA, NFS, Reclamation and
the Native American tribes. The mitigation measures recommended by the tribes to date

SCO/CHAPT6.WPD/003672560 6-29
-------
CHAPTER 6 SECTION 4(F) EVALUATION
and incorporated in the PA include providing funding to the tribes for continuing
consultation through design and construction, providing access for the tribes to the TCP,
developing a statement of work for conducting additional studies of cultural landscapes in
the surrounding area, and providing Native American cultural interpretive exhibits. (See
Section 3.5.3.1 for further details.)

6.7.4 Noise

The Gold Strike Canyon Alternative would require consideration of mitigation measures in
the upper reaches of the Gold Strike Canyon Trail along the alignment where the predicted
noise levels would be increased by 26 decibels above me ambient noise levels (39 dBA). A
modeling/monitoring receptor site (R4/M4) located on the Gold Strike Canyon Trail was
used in me analysis of projected noise from the Gold Strike Canyon Alternative. Table 6-2
shows the effects of noise barriers constructed along the trail side of the U.S. 93 Bypass in
the vicinity of receptor R4/M4.

Table 6-2
Gold Strike Canyon Alternative
Mitigated Future Peak-Hour Noise Levels (dBA-LJ
Receptor Build, No 8-Foot 10-Foot 12-Foot 14-Foot 16-Foot
Location Mitigation Barrier* Barrier Barrier Barrier Barrier
R4/M4 65 59 59 59 59 59
"Minimum barrier height required to break the line-of-sight from an 11.5-foot truck exhaust stack and the noise
receptor.

Table 6-2 shows that noise barriers located on the outside shoulder of the elevated roadway
could reduce noise levels in the affected portion of the hiking trail to 59 dBA-Leq (hourly
equivalent sound pressure levels). However, the mitigated noise levels would still result in
a substantial increase over existing ambient levels (more than 15 dBA) under NDOT and
ADOT noise abatement policies.

Although the noise impact would not be mitigated below this federal and state criterion, an
insertion loss of up to 6 dBA would be feasible with the addition of noise barriers. Under
noise abatement policies of the FHWA, noise barriers would be constructed only if they are
determined to be reasonable and feasible (FHWA, Highway Traffic Noise Analysis and
Abatement - Policy and Guidance, June 1995). A 5-dBA noise reduction must be achieved
for the noise barriers to be considered feasible, which can be accomplished for the Gold
Strike Canyon Trail (as shown in Table 3-11). One reasonableness factor that can be
analyzed for recommended barriers is benefit-cost. To achieve the minimum noise
reduction of 5 dBA and break the line-of-sight along the portion of the hiking trail impacted
by the Gold Strike Canyon Alternative would require construction of approximately
5,170 feet of noise barriers located along about 7,000 feet (1.3 miles) of tiie roadway. The
barriers would begin near the trailhead off U.S. 93 (engineering station 45+50) and end at a
major side-canyon/sheep crossing bridge (station 115+50), where the roadway diverges
from the main canyon/trail and heads northeasterly (Figure 3-1).

To construct 5,170 feet of noise barriers at a height of 10 feet would cost approximately
$1,048,000 (subject to adjustment during final design). The barriers would be placed only
on the outside shoulder of the roadways and bridges facing the trail, but not in locations
where the trail lies under the elevated roadway. This mitigation cost would benefit the
hikers and rock-climbers using this hiking trail to the hot springs. The NFS estimates that

6-30 SCO/CHAPT6.WPD/003672560)
-------
CHAPTER 6 SECTION 4(F) EVALUATION
approximately 1,000 hikers currently use the Gold Strike Canyon Trail on an annual basis
(Jim Holland, personal communication, July 2,1998). Thus, the cost of the noise barriers
would equate to approximately $1,000 per hiker annually, or about $50 per hiker over a
20-year period.

Although the FHWA noise abatement policy does not have a specific guideline for the
number of people to be protected, as compared against the total cost of noise abatement,
this is a critical factor in making a determination on the reasonableness of the cost of noise
mitigation, and it needs to be considered during selection and design of the preferred
project alternative. This cost may not be reasonable considering that the total number of
hikers using the Gold Strike Canyon Trail is very small compared to the total number of
visitors to the LMNRA (9.7 million in 1997) and since the barriers will not eliminate the
substantial increase over existing ambient levels (i.e., more than 15 dBA). Even with
mitigation, the projected traffic noise level from U.S. 93 through the canyon would be 20
dBA greater than existing ambient conditions. The final decision on installing noise
abatement barriers would be made during completion of project design if the Gold Strike
Canyon Alternative were selected in the Record of Decision.

6.7.5 Recreation Resources

Construction safety practices will require that nets be used under the work area during
bridge construction to protect areas below from falling debris, tools, equipment, or building
materials. Some seasonal and daily blasting restrictions may be imposed throughout the
construction period. Restrictions and schedules for blasting will be determined before
construction. Construction of the Promontory Point bridge may require access restrictions
to Hoover Dam from Lake Mead; however, periodic closures would be coordinated with
lake tour operators. Construction of the Sugarloaf Mountain bridge may cause minor
interruptions in access for the rafting concession and canoeing put-ins; however, conflicts
can be avoided by coordinating launching activities with construction access. Access to the
Gold Strike Canyon Trail would be prohibited during all phases of construction and the
rafting concession will continue to operate with minor interruptions.

6.8 Coordination

Two agencies have jurisdiction over Section 4(f) lands crossed by the U.S. 93 proposal. The
LMNRA is administered by the NPS and the HDNHL is administered by Reclamation as a
part of the HDRA.

Reclamation originally proposed the bridge project in 1965, and they issued the Notice of
Intent and initiated scoping meetings as the lead agency in 1990. The NPS, as custodian
over the park land involved in this proposal, has taken an active role in all planning phases
of the proposed project. NPS is a member of the PMT, which was established by
Reclamation in 1989 to oversee project planning, environmental studies, design
development, and project funding. The PMT is an interagency project management team
composed of the NPS, the Arizona and Nevada Divisions of the FHWA, NDOT, ADOT, and
Reclamation. Representatives from these agencies attended monthly meetings beginning in
November 1989 until Reclamation stopped work in 1993. The PMT meetings were
reinitiated in 1997 under the FHWA, Central Federal Lands Highway Division as lead
agency. This team has participated in reviews of the project area, environmental studies,
preliminary engineering, and the EIS throughout the planning process. The Western Area
Power Administration (WAPA), U.S. Army Corps of Engineers, EPA, USFWS, NDOW, and

SCO/CHAPT6.WPD/003672560 6-31
-------
CHAPTER 6 SECTION 4(F) EVALUATION
AGFD have also met with the PMT and have provided input on project alternatives and
purpose and need.

Site visits and field interviews with Native American tribal elders were conducted by the
University of Arizona during May and June of 1998. This resulted in a draft report
concluding that a potentially significant traditional cultural property (TCP) may exist in the
vicinity of the bypass project. Following circulation of the draft report/the Nevada SHPO
requested that FHWA conduct an ethnohistoric study to provide documentary context for
assessing the potential TCP identified during the 1998 field interviews. Further, the Nevada
SHPO requested that FHWA commence formal government-to-government consultation
with the affected Native American tribes concerning the significance and National Register
eligibility of the potential TCP in the project area. The Arizona SHPO also requested
further consideration of potential TCPs in the area.

During the first government-to-government consultation meeting, the tribes requested that
the 1998 studies be expanded to other locations and include additional tribes and elders.
Subsequent studies by the University of Arizona and W & S Consultants and additional
government-to-government consultations were conducted in 2000. These efforts resulted in
an FHWA determination, and Nevada and Arizona SHPO concurrence, that the Gold Strike
Canyon and Sugarloaf Mountain TCP is eligible for listing on the National Register of
Historic Places. Continuing government-to-government consultations between FHWA and
Native Americans, and Native American participation in the DAP, will be utilized to
minimize and mitigate impacts to the TCP.

Consultations between FHWA and the Nevada and Arizona SHPOs resulted in concurrence
on the adverse effects of the undertaking on historic properties and signing of a
Programmatic Agreement in December 2000. FHWA will continue to consult with the
Advisory Council on Historic Preservation, the SHPOs, and other signatories to implement
the terms of the PA during the design and construction phases of the Hoover Dam Bypass.

Consultations will also continue with the NFS and Reclamation, as the officials having
jurisdiction over the affected Section 4(f) lands, throughout the design and construction
phases. As mandated under Section 6(f) of the Land and Water Conservation Fund (LWCF)
Act, the NFS must also assure that any conversion of LWCF purchased or improved lands is
compensated with replacement lands of equal value, location, and usefulness. In a letter
dated April 30,1998, the FHWA requested information from the following agencies to
determine whether any LWCF monies were used to purchase or improve any of the
recreational lands potentially impacted by the Hoover Dam Bypass Project: Arizona State
Parks, Nevada Division of State Parks, NFS Midwest Support Office (for lands in Arizona),
and NFS Great Basin Support Office (for lands in Nevada). The NFS has responded by
letter dated May 18,1998, indicating no LWCF monies were used to purchase or improve
any LMNRA lands affected by the project.
I 6.9 Determination
Based upon the above considerations, there is no feasible and prudent alternative to the use
of Section 4(f) land and the proposed action includes all possible planning to minimize
harm to the Lake Mead National Recreation Area, the Hoover Dam National Historic
Landmark, and the Gold Strike Canyon and Sugarloaf Mountain TCP resulting from such
use.
6-32 SCO/CHAPT6.WPD/003672560)
-------
CHAPTER 7
Coordination and Consultation
7.1 Introduction
A Public Involvement Strategy was developed for this project. The strategy was prepared
following interviews with 17 key stakeholders to assess information needs and appropriate
tools for communicating information about the project and receiving input from the public.
Those stakeholders are listed below.
Bill Smith, Boulder City Councilman

Lou Sorenson, Kingman City Manager

Larry Castillo, Mohave County
Commissioner

Kevin Hill, Henderson City Councilman

Bruce Woodbury, Clark County
Commissioner

Kurt Weinrich, Director
Regional Transportation Commission

Randy Harness, Conservation Chair
Sierra Club

Jim Moore
Nature Conservancy

Joyce Larkin
Hoover Dam Visitor Center

Brad Benson, Chairman
CAUTION
Cheryl Ferrance
Boulder City Chamber of Commerce

Trish Williamson
Public Relations Coordinator
Las Vegas Chamber of Commerce

Ray Chamberlain or Ted Scott
American Trucking Association

Dave Berry
Swift Transportation Company

Terry Smalley
Executive Vice President

Daryl E. Capurro, Managing Director
Nevada Motor Transport Association

David Creer, Executive Director
Utah Motor Transport Association

Stan Randolph, Consultant
California Trucking Association
A total of six project newsletters were distributed for public information. Public
participation and comment on potential environmental concerns were encouraged through
two of these newsletters, three public open houses, and by providing project-dedicated
voice mail and a project web site. Three public hearings were held for public comment on
the DEIS in October 1998. Appendix C contains agency correspondence. Volume n
contains a detailed description of the DEIS public hearings and the comments received.
SCO/CHAPT7.WPD/003672784
7-1
-------
CHAPTER 7 COORDINATION AND CONSULTATION
7.2 Public Scoping

Following a May 1990 Notice of Intent published in the Federal Register, Reclamation
initiated the EIS and began the scoping process. Public scoping meetings were held in June
1990 in Kingman, Arizona, and Boulder City and Las Vegas, Nevada. In Boulder City, there
was general concurrence that a new crossing was needed to remove traffic from Hoover
Dam; however, the public was divided on the solution. Some preferred to have a bypass
around Boulder City in addition to Hoover Dam, while others felt that any road that
bypassed Boulder City would severely impact downtown businesses. A newsletter, titled
Update, was published in January 1991 and sent to interested individuals. Interviews with
numerous community members and several meetings with interested members of the
public, the Boulder City Chamber of Commerce, members of the Boulder City Council, and
other organizations also occurred.

7.3 Public Comment Meetings

The FHWA filed a Notice of Intent in September 1997 to announce FHWA as the new lead
agency for environmental review of the project. FHWA conducted three public open
houses to allow comment on the alternatives carried forward from the June 1990 scoping
meetings. The public open houses were noticed in the first newsletter mailed in early
October 1997 and in the following newspapers: Las Vegas Review Journal, Las Vegas Sun,
Kingman Miner, Arizona Republic, and Boulder City News. A press release announcing the
public open houses was distributed to local media outlets through NDOT and ADOT public
affairs offices.

7.3.1 Kingman, Arizona, Public Open House Held October 27,1997

The first public open house was held in Kingman. The meeting was informal, consisting of
six stations with a display board at each station. The display boards included the three
proposed alternatives, the project schedule, the environmental review process, and an aerial
photograph of the proposed project area. Comments were noted on flip chart pads at each
station, and comment sheets were provided as handouts. Comments were varied and
included concern for project funding, habitat impacts, existing hazardous roadway
conditions, and consideration of a north-south alternative.

7.3.2 Boulder City, Nevada, Public Open House Held October 28,1997

The second public open house was held in Boulder City. The meeting format was the same
as for the Kingman meeting. Public comments were extensive and focused primarily on
considering other alternative crossings, specifically those to the south, bypassing Boulder
City. Other comments related to mitigation of traffic congestion, pedestrian safety, wildlife
impacts, and funding and schedule.

7.3.3 Las Vegas, Nevada, Public Open House Held October 29,1997

The third and final public open house was held in Las Vegas. The meeting format was the
same as for the Kingman and Boulder City meetings. Comments focused on pedestrian
safety, truck traffic considerations, visual impacts of a new crossing, project funding, and
general support for one of the three alternatives.
7-2 SCO/CHAPT7.WPD/003672784
-------
CHAPTER 7 COORDINATION AND CONSULTATION
7.4 Public Agency Partnering Session Held October 29,1997

A partnering session with federal, state, and local agencies was conducted early in the
project. The session was to inform these agencies of the Project Management Team's
direction to complete the environmental review process, discuss individual agency issues
and concerns about the project, and develop a partnership and promote communications
among the agencies. The session resulted in a Team Charter signed by all participants
acknowledging a willingness to work together to achieve the best possible project.

7.5 Project Management Team Meetings

The Project Management Team, described in Chapter 1, met regularly to discuss the project,
review interim work products, and provide guidance and direction for preparing the EIS
and other permit applications. In 1998 meetings were held on January 20, March 17, and
May 12. In 1999, meetings were held on February 9, April 20, June 29, and November 15. In
2000, meetings were held on April 12, June 13, July 11, October 4, and November 30.

7.6 Public Outreach

A project presentation was developed to inform and educate stakeholders and the general
public. Presentations to local agencies were given, and letters were sent to local
governments and entities offering to give presentations to their staffs and constituents.
Copies of these letters are found in Appendix C, Correspondence.

The presentation was made to the Laughlin Town Advisory Board in a public meeting on
April 14,1998. The FHWA Project Manager also presented the project and was available for
questions on a live call-in televised program, NDOT Update, broadcast on channels 42 and
63 from Las Vegas on May 15,1998.

In addition to DEIS public hearings held on October 13,14, and 15,1998, presentations
about the project and the EIS process were made at annual Transportation Conferences
jointly sponsored by the University of Nevada, Las Vegas; the American Society of Civil
Engineers; and the Institute of Transportation Engineers in October 1998 and in September
1999. Similar presentations were made at the 1998 and 1999 Annual Statewide Conferences
of the Arizona Public Works Association and at the 1999 and 2000 Annual Arizona
Conferences on Roads and Streets.

A project web page was developed (http:/ /www.hooverdambypass.org/') to provide
project information including details on alternatives, an explanation of the environmental
review process, a project schedule, and information material that is developed. An e-mail
address was also established (haussler@road.cflhd.gov) for users to provide feedback to the
Project Management Team.

7.7 DEIS Public Review and Comment

SCO/CHAPT7.WPD/003672784 7-3
-------
CHAPTER 7 COORDINATION AND CONSULTATION
web site, with an online commenting feature. By November 10,1998, the close of the DEIS
comment period, the web site was accessed over 1,500 times. There were a total of
approximately 160 public and agency commenters on the DEIS, including comments
received after the close of comment period. See Volume II for a full description of the DEIS
public input process, the comments received, and the responses to comments.

I 7.8 Consultation with Native American Tribes

Amendments to the regulations implementing the NHPA were published on July 1,1999.
These new regulations required initiation of formal government-to-government
consultations between FHWA, Reclamation, and NFS with Native American tribes affected
by the proposed project. The new regulation requires, in part:

...the Agency Official to consult with any Indian tribe...that attaches religious and
cultural significance to historic properties that may be affected by an undertaking.
Such Indian tribe...shall be a consulting party. The Agency Official shall ensure that
consultation in the Section 106 process provides the Indian tribe...a reasonable
opportunity to identify its concerns about historic properties, advise on the
identification and evaluation of historic properties, including those of traditional
religious and cultural importance, articulate its views on the undertaking's effects on
such properties, and participate in the resolution of adverse effects. It is the
responsibility of the Agency Official to make a reasonable and good faith effort to
identify Indian tribes...that shall be consulted in the Section 106 process.
Consultation with an Indian tribe must recognize the government-to-government
relationship between the Federal government and Indian tribes. The Agency Official
shall consult with representatives designated or identified by the tribal
government...(36 CFR 800.2).

FHWA, in partnership with NFS and Reclamation, began identifying additional Native
American tribes with an interest in the Hoover Dam Bypass in late summer through fall
1999. These activities occurred concurrently with consultation meetings held between
FHWA, NFS, and Reclamation with the Arizona and Nevada SHPOs and the ACHP; these
meetings addressed both the historic preservation issues associated with project impacts on
the HDNHL and the Native American tribes' cultural values. FHWA sent out invitations to
representatives of 17 tribes on December 9,1999, requesting their participation in formal
.consultation meetings on the project. To date, five meetings have been held with the tribal
representatives: on January 11,2000, in Laughlin, Nevada; on March 30,2000, at the Hoover
Dam Visitor Center; on May 8,2000, in Henderson, Nevada; and on August 15 and 16,2000,
and November 15,2000, in Boulder City, Nevada. The May 8 meeting was held with a Core
Consultation Group, consisting of six tribal representatives, that was delegated by the full
assembly of tribes to lead the consultation process with FHWA on their behalf. Attendance
by Native American tribal representatives at the government-to-government consultation
meetings has ranged from about 25 to 30 participants.

The Agency/Native American government-to-government consultation meetings resulted
in a Memorandum of Understanding (MOU) between the tribes and FHWA, and in the
tribes being included as invited signatories on the Programmatic Agreement (PA) for
treatment of historic properties affected by the Hoover Dam Bypass. The MOU and PA
stipulate that the Native American tribes will continue in a formal consultation role with
the agency officials involved in the project through its design and implementation.

7-4 SCCVCHAPT7.WPD/003672784
-------
CHAPTER 7 COORDINATION AND CONSULTATION
7.9 Permits

Permits and approvals are required to construct and operate the Hoover Dam Bypass
project. Table 7-1 summarizes the agency-regulated activities and required federal, State of
Nevada, State of Arizona, Clark County, and Mohave County permits and approvals
anticipated to construct and operate the alternatives at Promontory Point, Sugarloaf
Mountain, or Gold Strike Canyon.

Table 7-1
Permits and Approvals Anticipated for the Hoover Dam Bypass Project
Agency
Regulated Activity
Required Permit or Approval
Federal
U.S. Army Corps of Engineers

Federal ACHP
U.S. Bureau of Reclamation

U.S. Bureau of Reclamation
National Park Service

U.S. Coast Guard

U.S. EPA

U.S. Fish and Wildlife Service
Discharge of dredge or fill material
into U.S. waters
Coordination of project design and
construction to minimize impacts on
historic properties

Use of additional right-of-way for
roadway and bridge
Water use during construction
Acquisition of additional right-of-way
for roadway and bridge
Impacts on navigable waters

Stormwater discharges
Impacts on special-status vegetation
and wildlife species
Section 404 Permits

Programmatic Agreement
between FHWA, NSHPO,
ASHPO, and ACHP (Section
106 consultation)
Easement

Water Use Permit
Easement

Section 9 Permit

National Pollution Discharge
Elimination System (NPDES)
Permit

Biological Opinion
Nevada State
Nevada State Historic
Preservation Officer (NSHPO)
Nevada Division of
Environmental Protection
Nevada Division of
Environmental Protection
Nevada Division of
Environmental Protection
Nevada Division of
Environmental Protection
Nevada Division of
Environmental Protection
Nevada Division of Water
Resources
Nevada Department of
Transportation
Nevada Division of Wildlife
Impacts on cultural resources

Impacts on water quality

Construction activities disturbing
more than 5 acres of land
Discharge to surface waters

Approval of plans and specifications
necessary prior to construction start
Discharge to surface waters

Water use during construction

Coordination of project design,
construction, operation, maintenance,
and financing

Potential disturbance of desert
tortoise
Section 106 Review

Section 401 Water Quality
Certification
General Stormwater Permit for
Construction Activities
National Pollutant Discharge
Elimination System Permit
Design Review of Plans and
Specifications
Temporary or Permanent
Discharge Permit
Water Right Permit

Memorandum of Agreement
between FHWA, NDOT, and
ADOT

Handling Permit
SCO/CHAPT7.WPD/003672784
7-5
-------
CHAPTER 7 COORDINATION AND CONSULTATION
Table 7-1
Permits and Approvals Anticipated for the Hoover Dam Bypass Project
Agency
Regulated Activity
Required Permit or Approval
Nevada Division of Wildlife
Nevada State Division of State
Lands
Potential impacts on common and Permit
special-status wildlife species

Acquisition of right-of-way in vicinity Easement
of Colorado River (Gold Strike
Alternative only)
Arizona State
Arizona State Historic
Preservation Officer (ASHPO)
Arizona Department of
Environmental Quality or Arizona
Department of Water Resources
Arizona Department of
Environmental Quality or Arizona
Department of Water Resources
Arizona Department of
Environmental Quality or Arizona
Department of Water Resources
Arizona Department of
Environmental Quality or Arizona
Department of Water Resources

Arizona Department of
Environmental Quality or Arizona
Department of Water Resources
Arizona Department of
Environmental Quality or Arizona
Department of Water Resources

Arizona Department of
Environmental Quality
Arizona Department of Water
Resources
Arizona Department of
Transportation

Arizona Game and Fish
Department
Impacts on cultural resources

Impacts on water quality
Construction activities disturbing
more than 5 acres of land
Discharge to surface waters
Approval of plans and specifications
necessary prior to construction start

Discharge to surface waters
Portable air pollution sources
Classification of construction waste
material and transport of solid wastes
generated to an ADEQ-approved
facility, at the contractor's option

Water use during construction
Coordination of project design,
construction, operation, maintenance,
and financing
Potential impacts on common and
special-status wildlife species
Section 106 Review

Section 401 Water Quality
Certification

General Stormwater Permit for
Construction Activities

National Pollutant Discharge
Elimination System

Design Review of Plans and
Specifications

Temporary or Permanent
Discharge Permit

Permit
May require facility approval
(waste stored onsite more than
90 days)

Water Right Permit

Memorandum of Agreement
between FHWA, NDOT, and
ADOT
Permit
Clark County*
Clark County Health District,
Air Pollution Control District
Clark County Health District,
Air Pollution Control District
Clark County Planning
Department
Dust emissions from construction
activities
Emissions from portable emissions
units used at project construction
site; examples include but are not
limited to rock crushers, generators,
and cement plants
Construction of aboveground
structures in Clark County
Dust Control Permit
Various Location Permit
Use Permit
7-6
SCO/CHAPT7.WPD/003672784
-------
CHAPTER 7 COORDINATION AND CONSULTATION
Table 7-1
Permits and Approvals Anticipated for the Hoover Dam Bypass Project
Agency
Regulated Activity
Required Permit or Approval
Clark County Building
Department
Clark County Department of
Public Works and Community
Development
Clark County Department of
Public Works and Community
Development
Construction of aboveground
structures in Clark County
Grading at project site
Drainage associated with grading
and construction activity
Building Permit

Grading Permit

Drainage Study
Mohave County"
Mohave County
Mohave County

Mohave County

Mohave County
Mohave County
Emissions from portable emissions
units used at project construction
site; examples Include but are not
limited to rock crushers, generators,
and cement plants
Construction of aboveground
structures in Mohave County
Construction of aboveground
structures in Mohave County
Grading at project site
Drainage associated with grading
and construction activity
Various Location Permit
Use Permit

Building Permit

Grading Permit
Drainage Study
The federal government complies with county permitting requirements (personal communication, Kris Mills, Reclamation,
July 2,1998)
SCO/CHAPT7.WPD/003672784
7-7
-------
CHAPTER 7 COORDINATION AND CONSULTATION
This page intentionally left blank.
7-8 SCO/CHAPT7.WPD/003672784
-------
CHAPTERS
List of Report Preparers
Federal Highway Administration

James Roller, P.E.
Project Manager (Retired)
CFLHD
31 years' experience in highway engineering, FHWA
B.S., Civil Engineering

Terry Haussler, P.E.
Program and Administration Engineer
CFLHD
19 years' experience in highway engineering, FHWA
B.S., Civil Engineering

Dave Zanetell, P.E.
Project Manager
CFLHD
12 years' experience in design and construction
M.S., Civil Engineering and Construction Management

George Walton, P.E.
Design Engineer
CFLHD
12 years' experience in design and construction
B.S., Civil Engineering

Rick Gushing
Environmental Planning Engineer
CFLHD
18 years' experience in highway design and environmental compliance
B.S., Civil Engineering

Stephen D. Thomas
Environmental Program Manager
Arizona Division
21 years' experience in highway project development
A.A., Civil/Mechanical Engineering

Conway Barlow
Right-of-Way and Environmental Programs Manager
Nevada Division
32 years' experience in highway project development
B.S., Business Management
SCO/CHAPT8.WPD/003672785 8-1
-------
CHAPTER 8 LIST OF REPORT PREPARERS
Ted Bendure
Environmental Program Manager
Nevada Division
10 years' experience in environmental planning
M.S., Resource Economics

Arizona Department of Transportation

George E. Wallace, P.E.
Roadway Studies Manager
25 years' experience in design/project development
B.S., Civil Engineering

Richard M. Duarte
Manager of Environmental Planning
21 years' experience in construction and environmental management
B.S., Multiple emphasis in Environmental Quality and Construction Technology

Nevada Department of Transportation

Tom Greco, P.E.
Project Manager
28 years' experience in design and project management
A.A., Business Management

Bill Crawford, P.E.
Chief Bridge Engineer
22 years' bridge design, project management, and management experience
B.S., Civil Engineering

Daryl James, P.E.
Chief, Environmental Services Division
23 years' experience engineering
B.S., Mechanical Engineering

U.S. Bureau of Reclamation

Kris Mills, P.E.
Water Resource Manager
22 years' experience in design, construction, contract administration, planning, project
management, and program management
B.S., Civil Engineering

Dave Curtis
Environmental Specialist
18 years' experience in range management, environmental planning, and environmental
compliance with Reclamation and BLM
B.S., Wildlife Biology
8-2 SCO/CHAPT8.WPD/003672785
-------
CHAPTER 8 LIST OF REPORT PREPARERS
U.S. National Park Service

Bill Burke
Resource Management Specialist
Lake Mead National Recreation Area
30 years' experience with NFS in natural resource management
B.S., Wildlife Management

Jim Holland
Planner
Lake Mead National Recreation Area
21 years' experience in resource and recreation management
M.S., Biology
CH2M HILL

Project Management
Brian O'Halloran, Lead Consultant
Environmental Planner
23 years' experience
Masters, City Planning
B.A., Economics

Jeff Bingham, EIS Project Manager
Environmental Planner
25 years' experience
M.S., Environmental Science
B.A., Anthropology

Ken MacDonald, EIS Task Leader
Environmental Scientist
16 years' experience
M.B.A.
B.S., Biological Science

Air Quality
Kent Norville
Water Resource Engineer
15 years' experience
Ph.D., Geophysics
B.S., Physics

Biological Resources
Marjorie Castleberry
Biologist
9 years' experience
B.S., Wildlife Biology
Water Resources

Steve Cooke
Water Resource Engineer
16 years' experience
M.S., B.S., Civil Engineering

Wetlands
Gretchen Honan
Environmental Scientist
19 years' experience
M.S., Marine Affairs
B.A., Physical Geography

Cultural Resources
Jim Bard
Environmental Planner
23 years' experience
Ph.D., M.A., B.A., Anthropology

Robin McClintock
Planner
16 years' experience
B.S., Anthropology

Land Use
Mike Urkov
Environmental Planner
6 years' experience
M.S., Water Resources
B.S., Natural Resources
SCO/CHARTS. WPD/003672785
8-3
-------
CHAPTER 8 LIST OF REPORT PREPARERS
Visual Resources, Energy, Socioeconomics,
Recreation, Land Use

Wendy Haydon
Environmental Planner
11 years' experience
M.S., Recreational Administration
B.A., Environmental Studies

Transportation Analysis

Tom Ragland
Transportation Engineer
22 years' experience
M.S., Civil Engineering
B.S., Civil Engineering

Michael Lasko
Civil Engineer
9.5 years' experience
B.S., Civil Engineering

Scott Jarvis
Civil Engineer
2 years' experience
B.S., Physics
B.S., Civil Engineering

Mike Kies
Transportation Engineer
12 years' experience
B.S., Civil Engineering

Otto Vydra
Transportation Engineer
31 years' experience
M.S., Civil Engineering
B.S., Civil Engineering

Socioeconomics
Roger Mann
Economist
19 years' experience
Ph.D., Agricultural Economics
M.S., Agricultural Economics
B.S., Resource Economics
Noise
Jason Kester
Civil Engineer
10 years' experience
B.S., Mechanical Engineering

Teri Burk
Environmental Scientist
3.5 years' experience
B.S., Biology

Hazardous Materials
Pam Bates
Hazardous Materials Specialist
8 years' experience
B.S., Environmental and Occupational
Health

Cumulative Impacts
Karen DiCarlo
Environmental Planner
10 years' experience
M.S., Environmental Planning
B.A., Social Ecology

| University of Arizona

| Ethnographic Study
Richard Stoffle
Anthropologist
30 years' experience
Ph.D., Anthropology

| Associated Cultural Resource Experts

| Historic Resources Survey
Kurt Schweigert
22 years' experience
M.A., American History
B.A., American History
8-4
SCO/CHAPT8.WPD/003672785
-------
CHAPTER 8 LIST OF REPORT PREPARERS
W. & S. Consultants

Ethnohistoric Assessment

David Whitley
Anthropologist
27 years' experience
Ph.D., Anthropology
SCO/CHAPT8.WPD/003672785 8-5
-------
CHAPTER 8 LIST OF REPORT PREPARBRS
This page intentionally left blank.
8-6 SCO/CHAPT8.WPD/003672785
-------
CHAPTER 9
References
Arizona Department of Transportation and Nevada Department of Transportation. Hoover
Dam Bypass Bridge Financial feasibility Study. Prepared by Hagler Bailly Services, Inc.
June 2000.
Arizona Department of Transportation (ADOT). Final Environmental Assessment and
Section 40 Evaluation for State Route 68 Design Concept Study. Project No. STP-068-1(4),
TRACS No. 068 MO 0 H3138 01C. Milepost 1.23 - Junction U.S. 93.1999.

. Arizona State Transportation Improvement Plan. 1994.

. U.S. 93 Development Study. 1993.

-. Colorado River Crossing—Phase B Corridor Study Developed Bridge Alternatives.
January 1992.

Arizona Game and Fish Department. Presence and Movements of Peregrine Falcons in Area of
the Proposed Black Canyon Bridge Project—Final Report. June 1992.

. Movements and Habitat Use of Desert Bighorn in the Black Canyon Area. March
1992.

Berry, K. H. Avian Predation on the Desert Tortoise (Gopherus agassizii) in California.
U.S. Bureau of Land Management, Riverside, California. Report to Southern California
Edison Company, Rosemead, California. 1985.

Blake, J. G. Birds of the Lake Mead National Recreation Area. Technical Report No. 1, Biota of the
Lake Mead National Recreation Area. National Park Service/University of Nevada. Las
Vegas, Nevada. 1978.

Boarman, W. I. The Raven Management Program: Status as of 1992. Paper presented at the
1992 Desert Tortoise Council Symposium. 1992.

Bondello, M. C. The Effects of High-Intensity Motorcycle Sounds on the Acoustical Sensitivity of
the Desert Iguana (Dipsosaurus dorsalis). M.A. Thesis, Biology Department, California
State University, Fullerton. 1976.

Bondello, M. C., A. C. Huntley, H. B. Cohen, and B. H. Brattstrom. The Effects of Dune Buggy
Sounds on the Telencephalic Auditory Evoked Response in the Mojave Fringe-Toed Lizards
OJma scoparia). Report, Contract Number CA-060-CT7-2737, U.S. Department of the
Interior, Bureau of Land Management, Riverside, California. 1979.

Brown, D. E. (Ed.). Biotic Communities of the American Southwest - United States and Mexico.
1982.

Bureau of Land Management. Draft Raven Management Plan for the California Desert
Conservation Area. Prepared by Bureau of Land Management, California Desert District,
Riverside, California. April 1990.

Burke, Bill. Resource Management Specialist. National Park Service. Personal
communication with Wendy Haydon/CH2M HILL on September 10,1998.
SCO/CHAP9.WPD/003672786 9-1
-------
CHAPTER 9 REFERENCES
Bury,R. B. Desert Tortoises and Off-Road Vehicles. Do They Mix? Proceedings of the 1978
Desert Tortoise Council Symposium. 1978.

Clark County Health District. Dust Control Permit Requirements. Revised July 1,1997.

Cooperative National Park Resources Study Unit. Desert Bighorn Movements and Habitat Use
in Relation to the Proposed Black Canyon Bridge Project. A first progress report. University
of Nevada, Las Vegas. 1990.

Cunningham, S. and L. Hanna. Movements and Habitat Use of Desert Bighorn in the Black
Canyon Area. Final Report. Arizona Game and Fish Department Research Branch.
Phoenix, Arizona. March 1992.

Desert Tortoise Council. Guidelines for Handling Desert Tortoises During Construction Projects.
Edward L. LaRue, Jr., editor. San Bernardino, California. Unpublished document
prepared for Fish and Wildlife Service, Bureau of Land Management, California
Department of Fish and Game, Nevada Department of Wildlife, Arizona Game and Fish
Department, and Utah Division of Wildlife Resources. 1994 (revised 1996).

Ebert, Donald W. and Charles L. Douglas. Desert Bighorn Movements and Habitat Use in
Relation to the Proposed Black Canyon Bridge Project: Nevada. Cooperative National Park
Resources Study Unit. Final Report. May 1993.

Ezzo, J. A., T. Majewski, J. H. Atschul, K. Knoblock, and M. T. Swanson. A Class I Cultural
Resources Survey for the Southern Nevada Water Authority Treatment and Transmission
Facility, Clark County, Nevada. Statistical Research Technical Series No. 55. Tucson.
1995.

Federal Highway Administration. Ha'tata (The Backbone of the River): American Indian
Ethnographic Studies Regarding the Hoover Dam Bypass Project. Prepared by Richard W.
Stoffle, et al., University of Arizona. Edited by CH2M HILL. July 1998. Supplement in
October 2000a.

. Hoover Dam Bypass Project: Ethnohistoric Overview and Assessment.
Prepared by David S. Whitley and Peter Nabokov, W&S Consultants. Edited by
CH2M HILL. October 2000b.
_. The Land Still Speaks: Traditional Cultural Property Eligibility Statement.
Prepared by University of Arizona and the American Indian Core Consultation Work
Group. Edited by CH2M HILL. October 2000c.

.. Comprehensive, Truck Size and Weight Study. FHWA-PL-00-029.
August 2000.
. U.S. 93 Hoover Dam Bypass Project Archaeological Resources Survey Report.
Prepared by CH2M HILL. April 2000.

. U.S. 93 Hoover Dam Bypass Project, Sugarloaf Mountain Alternative, Historic
Resources Survey. Prepared by Kurt P. Schweigert, Associated Cultural Resource Experts.
August 1999.

. Biological Assessment for the Hoover Dam Bypass Project. Prepared by
CH2M HILL. February 1999.
9-2 SCO/CHAP9.WPD/003672786
-------
CHAPTER 9 REFERENCES
_. Highway Traffic Noise Analysis and Abatement—Policy and Guidance.

_. Guidance for Preparing and Processing Environmental and Section 4(f)
June 1995.

Documents. T6640.8A. October 30,1987.

Freilich, Leitner & Carlisle. Mohave County, Arizona, General Plan. March 10,1995.

GB&L Consulting Engineers and Louis Berger Associates. Laughlin Bridge Location Study.
Prepared for Clark County, Nevada Department of Public Works. March 1,1996.

Highway Research Board. Highway Capacity Manual - Special Report. Third Edition.
Washington, D.C. 1994.

Holland, J. S., W. E. Miles, and P. J. Leary. Vascular Plants of the Lake Mead National
Recreation Area, Nevada/Arizona: Technical Report Number 3. Cooperative National Park
Resources Studies Unit. University of Nevada, Las Vegas. 1979.
Hunt, Constance E. and V. Huser. Down by the River: The Impact of Federal Water Projects and
Policies on Biological Diversity. Sponsored by the National Wildlife Federation. 1988.
Liston, C. R. and S. Grabowski. Characterization of the Aquatic Environment on Lake Mead Near
the Proposed Spring Canyon Pumped-storage Project, and Assessment of Potential Aquatic
Impacts. Bureau of Reclamation. 1988.

Luckenbach, R. A. What the ORVs are Doing to the Desert. 1975.

-. "Ecology and Management of the Desert Tortoise (Gopherus agassizii) in
California." In: R. B. Bury, editor. North American Tortoise: Conservation and Ecology.
U.S. Fish and Wildlife Service, Wildlife Research Report 12. 1982.

Maser, C., J. E. Rodiek, and J. W. Thomas. "Cliffs, Talus, and Caves." Wildlife Habitats in
Managed Forests, the Blue Mountains of Oregon and Washington. USDA Forest Service.
Ag. Handbook No. 553. 1979.

National Oceanic and Atmospheric Administration. Local Climatological Data. 1991.

Nevada Department of Highways and U.S. Department of Commerce, Bureau of Public
Roads. U.S. 93-466 Hoover Dam Origin and Destination Study. November 1968.

Nevada Department of Transportation and Arizona Department of Transportation.
Accident Data. 1994 through 1997.

Nevada Department of Transportation. Statewide Transportation Improvement Program. 1998.

. Statewide Transportation Improvement Program. 1997.

. U.S. 93 Colorado River Crossing Corridor Study. December 1994.
Nicholson, L. The Effects of Roads on Desert Tortoise Populations. Proceedings of the 1978
Desert Tortoise Council Symposium. 1978.
SCO/CHAP9.WPD/003672786 9-3
-------
CHAPTER 9 REFERENCES
Niles, W. E., C. L. Douglas, J. Holland, C. Downer, J. Blake, J. Schwartz, and G. T. Austin.
"The Biota of Lake Mead National Recreation Area, Nevada/Arizona: Project Report
No. 1, Annotated Checklist and Bibliography." Lake Mead Project Technical Report Series.
Cooperative National Park Resources Studies Unit. University of Nevada, Las Vegas.
1977.
Personal communication, Dan Jensen. U.S. Department of the Interior, Bureau of
Reclamation. December 2000.
Personal communication, Jeff Weaver. U.S. Department of the Interior, Bureau of
Reclamation. July 15,1998.
Personal communication, Jim Holland. National Park Service. July 2,1998.
Personal communication, Ron Opfer. Black Canyon Raft Tours. April 21,1998.
Personal communication, Kris Mills. U.S. Department of the Interior, Bureau of
Reclamation. April 17,1998.
Personal communication, Dan Jensen. U.S. Department of the Interior, Bureau of
Reclamation. April 17) 1998.
Personal communication, Bill Burke. National Park Service. April 17,1998.
Queen, R.L. Cultural Resource Report: Colorado Bridge Crossing/Hoover Dam Project Bridge
Crossing and Highway Alignment Survey. U.S. Department of the Interior, Bureau of
Reclamation, Lower Colorado River Region. 1992.
Stevens, Joseph E. Hoover Dam: An American Adventure. University of Oklahoma Press,
Norman, Publishing Division of the University. 1988.
U.S. Census Data. 1990.
U.S. Department of the Interior, Bureau of Reclamation, Lower Colorado Region.
Facilitating Traffic Flow, Alleviating Safety Hazards, and Expediting Access—Hoover Dam.
Boulder City, Nevada. September 1997.
-. Description and Assessment of Operations, Maintenance, and Sensitive Species of the
Lower Colorado River. 1996.
. Traffic Study: Colorado River Bridge. December 1993.
. Hoover Dam Bridge Crossing Cultural Resource Site Reassessment: Arizona Sites
DD:14:15, DD:U:16, DD:14:17, and DD:14:19. Report No. LC-NV-92-2. March 1993.
-. Hoover Dam Bridge Crossing Cultural Resource Site Reassessment: Nevada Sites
26CK4698,26CK4739,26CK4750,26CK4751,26CK4752, and 26CK4763. Report
No. LC-NV-92-2 (Nevada). March 1993.
. Traffic and Revenue Study for Colorado River Crossing. August 1992a.
. Colorado River Bridge—Hoover Dam, Phase B Corridor Studies. August 1992b.
. Colorado River Bridge—Hoover Dam, Arizona-Nevada. Phase B Corridor Studies.
August 1992c.
. Colorado River Bridge—Hoover Dam: Public Involvement Plan. May 15,1992.
9-4 SCO/CHAP9.WPD/003672786
-------
CHAPTER 9 REFERENCES
-. Level I Survey, Contaminant Survey Checklist of Proposed Real Estate Acquisitions.
Promontory Point Alignment. May 1992a.

. Level I Survey, Contaminant Survey Checklist of Proposed Real Estate Acquisitions.
Sugarloaf Mountain Alignment. Mayl992b.
-. Level I Survey, Contaminant Survey Checklist of Proposed Real Estate Acquisitions.
Gold Strike Canyon Alignment. May 1992c.

. Traffic Study: Colorado River Bridge—Hoover Dam. December 1991.

. Traffic Count. August 8,1991.

. Colorado River Bridge—Hoover Dam, Phase A Route Study. October 1990.

. Black Canyon Bridge, Colorado River Crossing, Hoover Dam. January 1986.

—. Analysis of Colorado River Crossing Below Hoover Dam. June 1983.

. Resume of Studies on Colorado River Crossing Below Hoover Dam. January 1972.
. A Study and Recommendations for Handling Traffic and Conducting Visitors at
Hoover Dam. April 1971.

U.S. Department of the Interior, National Park Service. Final Environmental Impact
Statement. Volumes I and II. Lake Mead National Recreation Area/Arizona-Nevada. 1986.

U.S. Department of Transportation. Highway Construction Noise: Measurement, Prediction,
and Mitigation. 1977.

U.S. Fish and Wildlife Service. Letter from Robert Williams to Terry Haussler, Federal
Highway Administration. September 4,1997a.

. Letter from Robert Williams to Terry Haussler, Federal Highway
Administration. November 21,1997b.

. Procedures for Endangered Species Act Compliance for the Mojave Desert Tortoise.
Regions 1,2, and 6. October 1992.

White, W.G. Hoover Dam Bridge Crossing Cultural Resource Site Reassessment: Nevada Sites
26CK4698,26CK4739, 26CK4750,26CK4751, 26CK4752, and 26CK4763. Report
No. LC-NV-92-2 (Nevada). U.S. Department of the Interior, Bureau of Reclamation,
Lower Colorado River Region. 1993a.

. Hoover Dam Bridge Crossing Cultural Resource Site Reassessment: Arizona Sites
DD:14:15, DD:14:16, DD:14:17, and DD:14:19. Report No. LC-NV-92-2 (Arizona).
U.S. Department of the Interior, Bureau of Reclamation, Lower Colorado River Region.
1993b.

Wildlife Society. Natural History and Management of Bats in California and Nevada.
Conference Proceedings. November 13-15,1996.
SCO/CHAP9.WPD/003672786 9-5
-------
CHAPTER 9 REFERENCES
This page intentionally left blank.
9-6 SCO/CHAP9.WPD/003672786
-------
CHAPTER 10
List of Agencies, Organizations, and Persons to

Whom Copies of the Environmental Impact

Statement Were Sent _

Hoover Dam Bypass

DEIS Distribution
(Prior to November 10, 1998 Close of Comment Period)

Project Management Team Department of Energy, Las Vegas, NV

George Wallace, ADOT, Phoenix, AZ Department oflnterior Headquarters,
0 Washington, DC
Rick Duarte, ADOT, Phoenix, AZ T,_A ... _
EPA Headquarters, Washington, DC
Daryl James, NDOT, Carson City, NV . .
' ' 3 EPA Regional Office, San Francisco, C A
Bill Crawford, NDOT, Carson City, NV . .
' FHWA, Region 9, San Francisco, CA
Steve Thomas, FHWA-AZ, Phoenix, AZ T-^.T, r , 1T j u j
FHWA, Federal Lands Headquarters,
Conway Barlow, FHWA-NV, Carson City, Washington, DC
NV FHWA, Headquarters, Washington, DC
Dave Curtis, Reclamation, Boulder City, , _„„._, . Ar7
I FHWA, Phoenix, AZ
Kris Mills, Reclamation, Boulder City, NV NPS' Dtocte' Washington, DC
NPS Lake Mead National Recreation Area,
Bill Burke, NPS-LMNRA, Boulder City, NV
| Boulder City, NV
Jim HoUand, NPS-LMNRA, Boulder City, TT_ xri.
U.S. Army Corps of Engineers, Reno, NV
James Roller, FHWA-CFLHD, Lakewood, U'S' Coast Guard' Afcinrf* CA
CO U.S. Fish & Wildlife Service, Reno, NV

Rick Gushing, FHWA-CFLHD, Lakewood, Western Area Power Administration,
CO Phoenix, AZ

FHWA~CFLHD' State Agencies (Arizona)

I ADOT, District Office, Kingman, AZ
Federal Agencies
AZ Department of Commerce, Phoenix, AZ
Advisory Council on Historic Preservation,
Golden, CO AZ Game and Fish Dept, Kingman, AZ

Advisory Council on Historic Preservation, AZ Dept of Environmental Quality,
Washington, DC Phoenix, AZ

| Bureau of Indian Affairs, Parker, AZ AZ State Historic Preservation Office,
Phoenix, AZ

SCO/CHAP10.WPD/003672787 10-1
-------
CHAPTER 10 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES OF THE ENVIRONMENTAL IMPACT STATEMENT WERE SENT
State Agencies (Nevada)
Colorado River Commission, Las Vegas,
NV
NV Department of Conservation and
Natural Resources, Carson City, NV
NDOT, District Office, Las Vegas, NV
NV Division of Wildlife, Las Vegas, NV
NV State Historic Preservation Office,
Carson City, NV
NV State Office of Community Services,
Carson City, NV
Local (City & County)
Boulder City Manager, Boulder City, NV
Clark County Board of Supervisors, Las
Vegas, NV
Lake Chamber of Commerce, Meadview,
AZ
Mohave County Board of Supervisors,
Kingman, AZ
Mohave County Public Works/Eng.,
Hackberry, AZ
Mohave County Planning and Zoning,
Kingman, AZ
Mohave County Supervisor, Bullhead City,
AZ
Libraries
Boulder City Public Library, Boulder City,
NV
Bullhead City Public Library, Bullhead
City,AZ
Clark County Public Library, Las Vegas,
NV
Green Valley Public Library, Henderson,
NV
Henderson Public Library, Henderson, NV
Kingman Public Library, Kingman, AZ
Laughlin Library, Laughlin, NV
10-2
Special Interest Groups
American Trucking Association,
Alexandria, VA
AZ Motor Transport Association, Phoenix,
AZ
CAUTION, Boulder City, NV
Nature Conservancy, Las Vegas, NV
NV Motor Transport Association, Las
Vegas, NV
NV Motor Transport Association, Sparks,
NV
Sierra Club, Las Vegas, NV
Private Individuals
Bettner, David
Brown, Nancy
Cross, Ellen
Davis, Mike
Hill, Ronald
Hughes, Nicholas
Jones, Lyle
Kuhr, Sonny
Pollack, Doug
Corporations
Blakesley International, Marina del Rey,
CA
BRW, Inc., Denver, CO
Carman & Associates, Tucson, AZ
EcoPlan Associates, Inc., Mesa, AZ
EQS, Phoenix Area Office, Phoenix, AZ
Figg Engineering, Denver, CO
Huitt-Zollars, Inc., Dallas, TX
JBR Environmental, Reno, NV
Koch Materials Co., Englewood, CO
SCO/CHAP10.WPD/003672787
-------
CHAPTER 10 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES OF THE ENVIRONMENTAL IMPACT STATEMENT WERE SENT
Steinman, Chicago, IL | Universities

Thomas Olsen Associates, Inc., Hemet, CA j University of Arizona, Tucson, AZ

Ty Lin International, San Francisco, CA | University of Nevada, Las Vegas, NV

Ultrasystems Environmental, Irvine, CA

URS-Greiner, Denver, CO
DEIS Distribution
(After November 10,1998 Close of Comment Period)
| Tribes
Algots, Mr. John, Fort Mohave Indian
Tribe, Needles, C A

Anderson, Mr. Curtis, Las Vegas Paiute
Colony, Las Vegas, NV

Anderson, Ms. Geneal, Paiute Tribe of
Utah, Cedar City, UT
Anderson, Mr. Kenny, Las Vegas Paiute
Colony, Las Vegas, NV

Arnold, Mr. Richard, Pahrump Paiute
Tribe, Pahrump, NV

Barrackman, Mr. Llewellyn, Fort Mohave
Indian Tribe, Needles, CA

Begay, Mr. Robert, Navajo Nation, Window
Rock,AZ
Begay, Mr. Tim, Navajo Nation, Window
Rock,AZ
Begaye, Mr. Kelsey A., Navajo Nation,
Window Rock, AZ

Benson, Ms. Gloria Bulletts, Paiute Tribe of
Utah, Cedar City, UT
Benson, Ms. Louise, Hualapai Tribe, Peach
Springs, AZ
Bowekaty, Mr. Malcomb, Pueblo of Zuni,
Zuni, NM

Bradly, Ms. Carmen, Kaibab Paiute Tribe,
Fredonia, AZ

Butler, Ms. Elda, Ahamakav Cultural
Society, Mohave Valley, AZ
Cabillo, Mr. Alex, Hualapai Tribe, Peach
Springs, AZ

Chaco, Mr. Paulson, Navajo Nation,
Window Rock, AZ

Chavez, Mr. David, Chemehuevi Tribal
Council, Havasu Lake, CA

Chiago, Mr. Ron, Salt River Pima-Maricopa
Indian Tribal Council, Scottsdale, AZ

Cloquet, Mr. Donald J., The Las Vegas
Indian Center, Las Vegas, NV

Cornelius, Ms. Betty, Colorado River Indian
Tribes, Parker, AZ

Downer, Dr. Alan, Navajo Nation, Window
Rock,AZ

Drye, Ms. Brenda, Kaibab Paiute Tribe,
Fredonia, AZ

Eddy, Mr. Daniel, Colorado River Indian
Tribes, Parker, AZ

Eddy, Mr. Larry, Chemehuevi, Poston, AZ

Escalanti, Mr. Kenney, Fort Yuma Quechan
Tribal Council, Yuma, AZ

Foster, Mr. Larry M., Navajo Nation,
Window Rock, AZ

Hamilton, Mr. Clay, The Hopi Tribe,
Kykotsmovi, AZ

Hayden, Ms. Nancy, Yavapai-Prescott
Tribe, Prescott, AZ

Helton, Ms. Nora, Fort Mohave Indian
Tribe, Needles, CA
SCO/CH AP10.WPD/003672787
10-3
-------
CHAPTER 10 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES OF THE ENVIRONMENTAL IMPACT STATEMENT WERE SENT
Honga, Mr. Monza, Hualapai Tribe, Peach
Springs, AZ
Jackson, Ms. Loretta, Hualapai Tribe, Peach
Springs, AZ
Jackson, Mr. Michael, Fort Yuma Quechan |
Tribal Council, Yuma, AZ
Jake, Ms. Vivian-Caron, Kaibab Paiute
Tribe, Fredonia, AZ
James, Ms. Evelyn, San Juan Southern
Paiute Tribe, Tuba City, AZ
James, Ms. Lynette, Yavapai-Prescott Tribe,
Prescott, AZ
Kinlichinia, Ms. Juanita, Moapa Paiute
Indian Tribe, Moapa, NV
Kuwanwisiwma, Dr. Leigh, The Hopi
Tribe, Kykotsmovi, AZ
Kuyvaya, Ms. Sue, The Hopi Tribe,
Kykotsmovi, AZ
Lehi, Mr. Johnny, San Juan Southern Paiute
Tribe, Tuba City, AZ
Makil, Mr. Ivan, Salt River Pima-Maricopa
Indian Tribal Council, Scottsdale, AZ
Mapatis, Mr. Aaron, Hualapai Tribe, Peach
Springs, AZ
Miller, Ms. Kami, Moapa Paiute Indian
Tribe, Moapa, NV
Miller, Ms. Lalovi, Moapa Paiute Indian
Tribe, Moapa, NV
Mitchell, Ms. Violet, Yavapai-Prescott
Tribe, Prescott, AZ
Mogart, Mr. Terry, The Hopi Tribe,
Kykotsmovi, AZ
Ogo, Ms. Linda, Yavapai-Prescott Tribe,
Prescott, AZ
Ohte, Mr. Darryl, Moapa Paiute Indian
Tribe, Moapa, NV
Otero, Ms. Linda Dv Fort Mohave Indian
Tribe, Mohave Valley, AZ
Owl, Ms. Pauline, Fort Yuma Quechan
Tribal Council, Winterhaven, CA
Panteah, Mr. Loren, Pueblo of Zuni, Zuni,
NM
Petach, Ms. Lynn, Chemehuevi, Reseda, CA
Pikyavit, Mr. Benn S., Kaibab Paiute Tribe,
Fredonia, AZ
Putesoy, Mr. Matthew, Havasupai Tribe,
Supai, AZ
Rice, Mr. Stan Jr., Yavapai-Prescott Tribe,
Prescott, AZ
Savala, Ms. Gevene, Kaibab Paiute Tribe,
Fredonia, AZ
| Seowtewa, Mr. Octavius, Zuni, Zuni, NM
Simplicio Mr. Dan, Pueblo of Zuni, Zuni,
NM
Smith, Mr. Edward, Chemehuevi Tribal
Tribe, Chemehuevi Valley, CA
Stoffle, Dr. Richard, University of Arizona,
Tucson, AZ
Susanyatame, Mr. (Ronald) Man, Hualapai
Tribe, Peach Springs, AZ
Taylor, Mr. Dalton, The Hopi Tribe, Second
Mesa, AZ
Taylor, Mr. Wayne, The Hopi Tribe,
Kykotsmovi, AZ
Tom, Mr. Eugene, Moapa Paiute Indian
Tribe, Moapa, NV
Welch, Mr. Russell, Colorado River Indian
Tribes, Parker, AZ
Wilder, Mr. Lonnie, Hualapai Tribe, Peach
Springs, AZ
Corporations
Dames & Moore, Phoenix, AZ
Hagler Bailly Services, Inc., Arlington, VA
Haley & Aldrich, Brea, CA
Haley & Aldrich, Denver, CO
10-4
SCO/CHAP10.WPD/003672787
-------
CHAPTER 10 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES OF THE ENVIRONMENTAL IMPACT STATEMENT WERE SENT
Las Vegas Review-Journal, Las Vegas, NV I Federal Agencies
| Bureau of Reclamation, Phoenix, AZ

| NFS, San Francisco, CA
Vollmer Associates LLP, New York, NY

Universities
University of North Texas, Lewisville, TX

Private Individuals

Best, Dr. Wallace H.

Cooper, Bill

Leporati, Arnold

Murray, Sam A.

Rummer, Bill
Hoover Dam Bypass
Summary DEIS Distribution
(Prior to November 10,1998 Close of Comment Period)

Arizona Elected Officials
Governor Jane Dee Hull
Senator Jon Kyi
Senator John McCain
Congressman Bob Stump

Nevada Elected Officials
Governor Bob Miller
Senator Richard Bryan
Senator Harry Reid
Kingman Chamber of Commerce, Kingman,
AZ
Las Vegas Chamber of Commerce, Las
Vegas, NV
Laughlin Chamber of Commerce, Laughlin,
NV

Federal, State, and Local Government
Agencies
AZ Department of Public Safety, Phoenix,
AZ
Congressman John Ensign

Congressman Jim Gibbons

Organizations

Boulder City Chamber of Commerce,
Boulder City, NV

Bullhead City Chamber of Commerce,
Bullhead City, AZ

Henderson Chamber of Commerce,
Henderson, NV
AZ Department of Water Resources,
Phoenix, AZ

AZ State Dept. of Commerce, Phoenix, AZ

AZ State Parks, Phoenix, AZ

Boulder City Council, Boulder City, NV

Bullhead City Manager, Bullhead City, AZ
Bureau of Indian Affairs, Phoenix, AZ

Bureau of Land Management, Las Vegas,
NV

Bureau of Land Management, Kingman, AZ
SCO/CHAP10.WPD/003672787
10-5
-------
CHAPTER 10 LIST OF AGENCIES, ORGANIZATIONS, AND PERSONS TO WHOM COPIES OF THE ENVIRONMENTAL IMPACT STATEMENT WERE SENT
Clark County Public Works Dept, Las
Vegas, NV
Henderson City Manager, Henderson, NV
Kingman City Council, Kingman, AZ
Kingman City Manager, Kingman, AZ
Las Vegas City Manager, Las Vegas, NV
Laughlin Town Manager, Laughlin, NV
Mohave County Public Works Dept,
Kingman, AZ
NV Commission on Tourism, Las Vegas,
NV
NV Planning Commission, Carson City,
NV
Regional Transportation Commission, Las
Vegas, NV
Southern Nevada Water System, Boulder
City,NV
Town Office of Searchlight, Searchlight, NV
Tribes
Chemehuevi Tribe, Lake Havasu, CA
Colorado River Indian Tribes,
(Chemehuevi) AZ
Hualapai Tribe, Peach Springs, AZ
Kaibab Paiute Tribe, Pipe Springs, AZ
Las Vegas Indian Center, Las Vegas, NV
Las Vegas Indian Tribe, Las Vegas, NV
Moapa Paiute Tribe, Moapa, NV
Paiute Indian Tribes of Utah, Cedar City,
UT
Pahrump Paiute Tribe, Pahrump, NV
Private Individuals
Friesema, Paul
Geddie, John
| Corporations
| EcoPlan Associates, Inc., Mesa, AZ
| Toll Roads Newsletter, Frederick, MD
I
10-6
SCO/CHAP10.WPD/003672787
-------
Index
air quality ES-3, ES-4, ES-8, ES-9,2-36,
3-1—3-6,3-19,3-31,3-49,3-57,3-68,
3-69,3-106,3-126,3-146,4-1,5-3,5-6,
5-15,5-16,6-21,6-22
alternative routes ... 2-7,2-8,2-43,6-4,6-5,6-20
Alternatives Studied in Detail ES-3,2-9,
2-15,6-5,6-24,6-25
Aquatic Communities 3-19,3-31
Archaeological Resources
Protection Act (ARPA) 3-48
Area of Potential Effects 1-12,3-48,3-49,
5-19,5-20,6-9
Areas of Controversy ES-8
average annual daily traffic (AADT) 1-15,
1-16,3-4,3-113—3-116,6-21,6-22

6
Best Management Practices (BMPs) — ES-11,
3-44, 3-46,4-1
Biology 3-16,3-35,3-38
Black Canyon ES-6,1-2,1-8—1-10,
1-12,3-16,3-19,3-23—3-25, 3-39,3-40,
3-54,3-70—3-74,3-97—3-101,3-106, 5-6,
5-9,5-21,6-11,6-15,6-17,6-19
Black Mountains 1-9,3-16,3-30,5-18
Boulder City Bypass 1-12,1-20,1-21,6-5
bridge designs 2-15,2-16,2-30,
2-35,3-32,3-74, 3-97,3-99,6-3, 6-4
D
Davis Dam 1-1,2-5,3-112,6-9,6-21
desert wash ES-4,3-16,3-19,3-20,
3-25,3-27,3-29,3-34,3-41
Desert tortoise ES-7, ES-10,1-12,
2-8,2-28,3-24,3-28—3-30, 3-33—3-39,
5-14,5-15,5-17—5-19,6-5,7-6
Design Noise Levels 3-8
El Dorado Mountains 3-16,3-30
employment 3-109,3-113,
3-116,3-146,4-4
Endangered Species Act 3-23,3-28,
3-38,5-8,5-13,5-17,5-19
energy 3-7,3-47,3-145
Environmental Justice 3-109,3-110,3-114
Federal Actions ES-9,3-110,5-19
Floodplains 3-41,3-43,3-44,3-53

H
Hazardous Materials ES-3, ES-6, ES-8,
ES-13,1-19,1-22,2-27,2-36,3-44, 3-61,
3-116,3-121—3-124,4-4
Highway Deficiencies 1-14
History 1-2,3-48,3-51,5-2
census data 3-110,3-112
Cliff Habitat 3-19,3-20,3-27,3-29,3-31
Colorado River Bridge
Project Management Team ES-1,1-7
Concurrent Resolution 1-22
Coordination and Consultation 7-1,7-3
creosote-bursage 3-27
Cultural Resources ES-5,2-6,2-28,3-48,
3-49,3-51,3-59,3-126,3-146,4-2,5-6,
5-10,5-16,5-19,5-20,6-11,7-5,7-6
I
Initial Identification of Alternatives ... 2-1,2-6
interference with dam operation 1-2
Irreversible and Irretrievable
Commitment of Resources 3-147
J
Joint Resolution 1-22
SCO/_MASTER.WPD/003672789
INDEX-1
-------
INDEX
Lake Mead National
Recreation Area (LMNRA) ES-3, ES-5,
ES-7,1-16,1-19,1-21,2-2,2-27, 2-36,
3-16,3-20,3-23,3-24,3-66—3-71,3-101,
5-2,5-4,5-15,5-20,5-21,6-6,6-9—6-11,
6-16,6-18,6-21,6-23—6-27,6-31,6-32
Land Use ES-12,1-13,
3-7,3-8,3-13,3-66—3-70,3-110,3-146,
3-147,4-3
listed species 1-12,3-28,
3-38,5-17
Logical Termini 2-43
Long-Term Productivity 3-146
LOS 1-9,1-15,2-8,3-4—3-6,
3-113—3-116,3-146,5-3,5-6

M
Mojave Desert ES-7,3-16,3-20,
3-27—3-29,3-33,3-38,5-5,5-17

N
National Historic Landmark (NHL) ES-5,
ES-8, ES-11, ES-12,1-2,1-11,1-12,2-6,
2-9,2-15,2-28,3-48,3-49,3-52,3-56,
3-57, 3-61,3-62,3-65—3-69, 3-72, 3-100,
4-2,4-3,5-2,6-6,6-10,6-11,6-16,6-19,
6-28, 6-29,6-32
National Historic Preservation Act 3-48,
3-69,3-97
National Pollutant Discharge
Elimination System (NPDES) 3-46,7-5,7-6
National Pollutant Discharge
Elimination System 3-46
Native American Graves Protection
and Repatriation Act (NAGPRA) 3-48
natural drainage 3-41,3-45
Noise ES-4, ES-10,
ES-12, ES-13,1-19,2-6,2-28,2-29, 2-36,
3-1,3-7—3-10,3-13—3-15,3-26, 3-27,
3-30,3-31,3-60,3-69,3-70,3-102,
3-105—3-107,3-109,3-114,3-115,3-126,
3-146,4-1,4-4, 5-3,5-6,5-15,5-16,6-1, 6-4,
6-9—6-11, 6-15—6-19,6-26, 6-27, 6-30,
6-31
noise-sensitive land uses 3-7
North American Free
Trade Agreement (NAFTA) ES-1,1-1,
1-21,2-7, 2-43, 3-15, 3-112, 3-146,3-148
o
Ozone 3-2,3-3,3-5
participate matter ES-4,3-2,3-3
permits and approvals ES-9,7-5
point of entry 1-1,3-112
population ES-4,1-2,4-4,5-11,5-18,5-19
precipitation 3-41,3-44
previous studies 1-7,2-1
Public scoping ES-1,2-6,7-2
Public Input ES-2,2-6,2-7,7-4
Public Outreach 7-3
purpose and need ES-3, ES-7,
ES-8,1-1,1-21, 2-6—2-8, 2-10,2-27,2-28,
2-30,2-36,2-43, 3-75, 3-100, 6-2, 6-4,
6-20,6-21,6-23—6-25, 6-32

Recreation Resources ES-6,2-6,
2-29,2-36,3-58,3-100,3-113,5-6,5-7,
6-21, 6-27,6-31
Riparian Areas 3-16,3-25,3-27,5-9
Roadway Capacity 1-14,3-115
safety ES-6, ES-8,1-2,1-8,1-15,
1-21,1-22,2-6, 2-7,2-9,2-10,2-27,3-15,
3-67,3-68,3-76,3-95,3-100,3-101,
3-103—3-108,3-114,3-115,3-121—3-125,
3-146,3-148,4-3,5-10,5-15,5-17,
6-4—6-6,6-11,6-22,6-23, 6-25, 6-27,
6-28, 6-31, 7-2
screening criteria ES-3,2-1,2-6,2-7,
2-9,2-10,2-29, 6-4
Screening Alternatives 2-6
Section 4(f) land ES-7,2-6,2-8,2-27,
2-28, 5-20,5-21, 6-5, 6-10,6-11, 6-16,
6-23,6-24,6-26,6-32
lNDEX-2
SCO/_MASTER.WPD/0036727B9
-------
INDEX
Short-term Uses 3-146
Socioeconomics 3-109,4-4
Special-status species 3-20,3-23,3-28
Statewide Transportation
Improvement Program 1-20
vehicle emissions 3-2—3-4
visitor experience 1-21,3-68
Visual Resources ES-6,3-1,3-70,
3-73,3-74,3-96,3-99, 3-100, 3-126,3-146,
3-147,4-3, 5-6,5-15, 5-17,5-21,6-28, 6-29
Toll option 2-43
Traditional Cultural Properties (TCPs)... ES-5,
1-13,2-28,3-48—3-51,3-55,3-58,5-9,6-32
traffic capacity 1-20,6-2
traffic volume ES-3,1-2,1-15,
2-36,2-43,3-4,3-7,3-9,3-13,3-145,5-14
transportation and circulation ES-6,3-109,
3-112,3-114,3-116,3-126,3-146,4-4,5-7
travel times ES-3,1-1,1-15,3-107,3-112
w
Water Resources ES-5, ES-6,
ES-11,3-41,3-44,3-46,3-54,3-121,4-1,
7-5,7-6
Waters of the United States 2-29,3-16,
3-19,3-21,3-32,3-33,3-41,4-1
wetlands 2-6,2-28,3-1,
3-16,3-19,3-27,3-147,5-13
Wildlife Resources 3-20
u
unavoidable adverse impacts 4-1—4-4
SCO/_MASTER.WPD/003672789
lNDEX-3
-------
INDEX
This page intentionally left blank.
INDEX-4 SCO/_MASTER.WPD/003672789
-------
-------
-------