Draft

San Gabriel Watershed and Mountains

Special Resource Study and Environmental Assessment

September 2011

Produced by the Pacifi c West Regional Offi ce

Park Planning and Environmental Compliance

National Park Service

San Francisco, California

U.S. Department of the Interior

Washington, DC

Top, left to right: Frank G. Bonelli Regional Park, NPS photo; Inspiration Point, Angeles National Forest, NPS photo.

Bottom: Eaton Canyon Natural Area, NPS photo.
California Broom Sage, Santa Clara River near Acton. Photo courtesy of BonTerra Consulting. 
Table of Contents

Abstract v

Executive Summary vi

1: Introduction 1 

PURPOSE AND NEED 3

ISSUES ADDRESSED IN STUDY 4

STUDY AREA 4

STUDY PROCESS 6

RELATED PLANS AND STUDIES 9

2: Resource Description 11

NATURAL RESOURCES 13

CULTURAL RESOURCES 52

RECREATIONAL RESOURCES 81

3: Resource Signifi cance 97

CRITERIA FOR NATIONAL SIGNIFICANCE 99

NATIONAL SIGNIFICANCE OF THE 

 SAN GABRIEL WATERSHED AND 

 MOUNTAINS STUDY AREA 99

NATIONAL SIGNIFICANCE CRITERIA 100

OVERALL CONCLUSIONS 116

OTHER SIGNIFICANT RESOURCES 

 WITHIN THE STUDY AREA 116

4: Suitability 121

INTRODUCTION 123

NPS THEMEATIC FRAMEWORK - 

 NATURAL AND CULTURAL THEMES 123

COMPARISON OF SIMILAR AREAS

 BY THEME 125

 SAN GABRIEL MOUNTAINS 125 

 PUENTE HILLS 144

SUMMARY: SUITABILITY 148

5: Feasibility and Need for 

 NPS Management 149

INTRODUCTION 151

EVALUATION OF FEASIBILITY FACTORS 151

NEED FOR NPS MANAGEMENT 157

6: Alternatives 159

INTRODUCTION 161

ISSUES ADDRESSED IN THE 

 ALTERNATIVES 161

OVERVIEW OF THE ALTERNATIVES 162

ALTERNATIVES CONSIDERED BUT 

 DISMISSED 163

ITEMS COMMON TO ALL 

 ACTION ALTERNATIVES 164

DESCRIPTION OF THE ALTERNATIVES 165

Continuation of Current Management 

(No Action Alternative) 165

Alternative A: San Gabriel Mountains 

National Recreation Area 171

Alternative C: San Gabriel Watershed 

National Recreation Area 175

Alternative D: San Gabriel Region 

National Recreation Area 184

7: Environmental 

 Consequences 199

INTRODUCTION 201

METHODS AND ASSUMPTIONS 201

ANALYSIS ASSUMPTIONS 201

IMPACT CRITERIA 203

POTENTIAL ENVIRONMENTAL 

 IMPACT TOPICS 204

EFFECTS ON BIOLOGICAL RESOURCES 206

EFFECTS ON CULTURAL RESOURCES 214

EFFECTS ON RECREATION USE AND 

 VISITOR EXPERIENCE 217

SOCIOECONOMIC EFFECTS 223

LAND USE 233

EFFECTS ON WATER RESOURCES 239

GOALS OF THE ALTERNATIVES 244 

ENVIRONMENTALLY PREFERRED 

ALTERNATIVE 245
ii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

8. Consultation & 

 Coordination 253

PUBLIC INVOLVEMENT 255

AGENCIES AND ELECTED OFFICIALS

TO WHOM COPIES OF THE REPORT 

WERE SENT 259

Appendices 265

APPENDIX A: STUDY LEGISLATION 267

APPENDIX B: SPECIES TABLES 268

APPENDIX C: NEW AREA STUDIES ACT 287

APPENDIX D: 2006 NPS MANAGEMENT 

POLICIES (SECTIONS 1.2 AND 1.3) 289

APPENDIX E: NATIONAL HISTORIC 

 LANDMARK CRITERIA SEC. 65.4 292

APPENDIX F: ALTERNATIVE B: SAN 

 GABRIEL PARKS AND OPEN SPACE 

 NETWORK 294

Acronyms & 

Abbreviations 295

Glossary 296

References 301

Preparers 316

Tables

Table 1: Signifi cant Earthquakes 

 Within or Near the Study Area 24

Table 2: Groundwater Basin 32

Table 3: Inventory of Cultural and 

Archeological Resources within the

 Study Area - Representation of 

 National Park Service Themes 75 

Table 4: Agencies Administering Parks 

 and Open Space in the Study Area 81

Table 5: Approximate Acreage of Study 

 Area Parks and Open Space 84

Table 6: Summary of National 

 Signifi cance 119

Table 7: Summary of Areas Suitable 

 for Inclusion in the National Park 

 System 148

Table 8: Feasibility Factors Issues and 

 Conclusions 156

Table 9: National Recreation Area 

 Annual Operating Budgets 181

Table 10: National Recreation Area 

 Annual Operating Budgets 189

Table 11: Summary of Alternatives 192

Table 12: Potential Environmental 

 Impact Topics 204

Table 13: Threats to Federal and State 

 Listed Threatened and Endangered 

 Plant and Animal Species 209

Table 14: Visitation to Major Recreation 

 Destinations within the Study Area 218

Table 15: Standards for Parks and 

 Open Space 219

Table 16: Children’s park access in 

 seven major cities 220

Table 17: Population 225

Table 18: Social and Cultural 

 Characteristics 226

Table 19: Income and Unemployment 227

Table 20: Tourism 228

Table 21: Spending and Economic Impacts 

 of Visitors to NPS Partnership Parks 

 on Local Economics, 2008 230

Table 22: Payroll Impacts of National 

 Park Partnership Parks without Visit 

 Counts, FY 2008 230

Table 23: Impaired Surface Waters 

 within the Study Area 241
 Table Of Contents iii

Table 24: Groundwater Basin 

 Water Quality 241

Table 25: Summary of Environmental 

 Consequences 246

Maps

Local Communities 10

Topography 15

Generalized Geology 18

Generalized Geology Legend 19

Regional Faults 23

Mineral Resources - Major Commodities 

 and Oil Provinces 27

Watersheds 29

Flood Protection Facilities 31

Groundwater Basins and Water 

 Supply Facilities 33

Vegetation 37

Federally-Listed Threatened and 

 Endangered Species 45

Designated Critical Habitat 46

Land Use 50

Native American Groups in the 

 Region 54

Ranchos 59 

Cultural Resources 80

Parks and Open Space 82

Trails, Bikeways and Scenic Highways 87

Nationally Signifi cant Regions 101

National Park Biophysiographic 

 Regions 124

Statewide California Walnut Woodland 

 and Forest Distribution 147

Continuation of Current Management 

 (No Action) 170

Alternative A: U.S. Forest Service 

 National Recreation Area 174

Alternative C: San Gabriel Watershed 

 National Recreation Area 182

Alternative C: San Gabriel Watershed 

 National Recreation Area River 

 Corridor Detail 183

Alternative D: San Gabriel Region 

 National Recreation Area: A 

 Partnership Linking Signifi cant 

 Resources and Recreation 190

Alternative D: A Partnership Linking 

 Signifi cant Resources and Recreation 

 Area Detail - River Corridor and 

 Puente Hills 191

 Acres of Parks Per 

 1,000 Residents 221

Figures

Figure 1: Location and Context 6

Figure 2: Median Household Incomes 227
iv Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 
 Abstract v

Abstract

The National Park Service (NPS) prepared the Draft 

San Gabriel Mountains and Watershed Special 

Resource Study to determine whether all or part of 

the study area is signifi cant, suitable, and feasible 

for designation as a unit of the national park 

system. Congress authorized this study in 2003. 

The study area covers approximately 700,000 acres 

of land in the greater Los Angeles metropolitan 

region, including urban communities, local and 

regional parks and open space, and 415,000 acres 

of the Angeles National Forest. 

Through the special resource study process, the NPS 

made the following determinations about the study 

area:

• Natural and cultural resources of the San Gabriel 

Mountains and Puente-Chino Hills are nationally 

signifi cant, in that they meet all four of the NPS 

criteria for national signifi cance.

• The study area is suitable for inclusion in 

the national park system because it represents 

natural and cultural resource types that are not 

already adequately represented in the national 

park system or protected by another land 

managing entity.

• The NPS determined that a collaborative 

partnership-based park unit which respects 

the complex mix of land use, ownership, and 

regulatory authority in the study area would 

be a feasible addition to the national park 

system. A large traditional national park unit, 

owned and operated solely by the National 

Park Service, is not feasible. 

• Need for NPS Management: NPS management 

in partnership with existing agencies and 

organizations is the best option for enhancing 

protection of signifi cant resources, for improving 

access to recreational opportunities in the region, 

and for providing coordinated interpretation and 

education about signifi cant resources.

The NPS evaluated four alternatives in the draft 

study, two include a role for the NPS:

No Action Alternative: Continuation of Current 

Programs and Policies. This is the “no action” 

alternative for this study, and assumes that current 

programs, policies, conditions, and trends would 

continue.

• Alternative A: San Gabriel Mountains 

National Recreation Area (A U.S. Forest 

Service Designation). In this alternative, 

Congress would designate the San Gabriel 

Mountains unit of the Angeles National Forest 

a National Recreation Area (NRA) that would 

continue to be managed solely by the U.S. 

Forest Service.

• Alternative B- San Gabriel Parks and Open 

Space Network (Dismissed): This alternative 

was dismissed from further consideration after 

public review of the preliminary alternatives 

(Newsletter 4). Some components of alternative 

B were incorporated into alternative D.

• Alternative C: San Gabriel Watershed 

National Recreation Area. This alternative 

proposes a river-based national recreation area 

that would raise the visibility of the San Gabriel 

River watershed, offer new educational and 

interpretive opportunities along the river and 

throughout the watershed, and improve riverbased recreation. This would be collaborativelymanaged, partnership-based national park unit. 

Partnership arrangements among federal and 

state agencies, local governments, non-profi t 

organizations, and area landowners would 

achieve the conservation, recreational, and 

educational goals of the national recreation area. 

The NPS would take a lead role in management 

of the partnership, particularly in the area of 

interpretation and education.

• Alternative D: San Gabriel Region National 

Recreation Area (A Partnership Linking 

Signifi cant Resources and Recreation). In 

this alternative, Congress would designate a 

larger scale national recreation area that would 

recognize and protect the signifi cant resources 

associated with the San Gabriel Mountains and 

Puente-Chino Hills, explore opportunities to 

protect and enhance interconnected ecosystems, 

provide important open space connections 

for recreation, and offer new educational and 

interpretive opportunities. The management 

approach of alternative D would be collaborative, 

as in alternative C. The NPS would take a lead role 

in management of the partnership, particularly in 

the area of interpretation and education.

The NPS prepared an environmental assessment to 

identify and analyze the potential environmental 

and socioeconomic consequences of the four 

alternatives. The NPS concluded that alternative 

D would be the environmentally preferable 

alternative because it would protect resources 

over a signifi cantly larger area, provide greater 

opportunities for recreation and visitation, provide 

greater socioeconomic benefi ts, and foster a 

larger framework for cooperative management as 

compared to alternatives A and C. 
vi Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Executive Summary

Background and Study Process

The San Gabriel River Watershed Study Act (PL 

108-042, July 2003) directed the National Park 

Service (NPS) to conduct a special resource study of 

(1) the San Gabriel River and its tributaries north of 

and including the city of Santa Fe Springs, and (2) 

the San Gabriel Mountains within the territory of 

the San Gabriel and Lower Los Angeles Rivers and 

Mountains Conservancy (RMC). 

The San Gabriel River Watershed Study Act also 

directed the NPS to consult with the RMC and other 

appropriate federal, state, and local government 

entities in conducting the study. Additionally, the 

study act directed the NPS to consider regional 

fl ood control and drainage needs and publiclyowned infrastructure such as wastewater treatment 

facilities.

The purpose of this special resource study is 

to determine whether any portion of the San 

Gabriel Watershed and Mountains study area is 

eligible to be designated as a unit of the national 

park system. Through the study process, the 

NPS identifi ed alternative strategies to manage, 

protect, or restore the study area’s resources, and 

to provide or enhance recreational opportunities. 

These alternatives explore partnerships and efforts 

to protect important resources in ways that do 

West Fork of the San Gabriel River. 2005. NPS photo. 
 Executive Summary Background And Study Process vii

not necessarily require the commitment of funds 

and staff by the NPS. This study will provide 

information to aid Congress, the U.S. Department 

of the Interior, and the NPS in determining whether 

designation of a unit of the national park system is 

desirable and appropriate. 

Study Area

The study area covers more than 1,000 square miles 

(over 700,000 acres) in the greater Los Angeles 

metropolitan region. It is one of the most densely 

populated and diverse areas of the United States. 

Most of the study area is located in Los Angeles 

County (approximately 85%), the remainder lies 

in Orange and San Bernardino counties. The U.S. 

Forest Service currently manages approximately 

two-thirds of the study area (415,000 acres in the 

San Gabriel Mountains) as part of the Angeles 

National Forest (ANF). With the exception of private 

inholdings and access facilities for fl ood protection 

structures and other utilities, the ANF remains 

primarily undeveloped. In close proximity to highly 

urban areas, the ANF provides a refuge for wildlife 

and recreational opportunities for the greater Los 

Angeles metropolitan region.

Legislative and Policy Direction

The National Park System New Area Studies Act 

and NPS management policies establish the basic 

process for evaluating potential new additions 

to the national park system. According to NPS 

management policies, a proposed addition to 

the national park system will receive a favorable 

recommendation from the NPS only if it meets all of 

the following four criteria for inclusion:

1. it possesses nationally signifi cant natural or 

cultural resources;

2. it is a suitable addition to the system;

3. it is a feasible addition to the system; and

4. it requires direct NPS management, instead of 

alternative protection by other public agencies 

or the private sector.

These criteria are designed to ensure that the 

national park system includes only the most 

outstanding examples of the nation’s natural and 

cultural resources, while recognizing that there are 

other management alternatives for preserving the 

nation’s outstanding resources.

National Park Service management alternatives 

are developed for study areas that meet all four of 

the criteria for inclusion, as listed above. Further 

defi nition of these criteria is provided in the related 

sections of this study.

Public Involvement

Throughout the study process, the planning team 

conducted extensive public outreach. The NPS 

held numerous public and stakeholder meetings 

throughout the region. Four newsletters were 

published at various stages of the study process 

and distributed to the study mail and e-mail lists. 

The study mailing list includes approximately 

2,000 addresses and the study e-mail list includes 

approximately 900 addresses. The NPS has made 

all information sent by mail and e-mail available on 

the study website, www.nps.gov/pwro/sangabriel. 

Additionally, numerous articles and opinion 

pieces covering the study have appeared in area 

newspapers.

The NPS initiated this special resource study in 

January 2005 with a newsletter describing the 

study process and opportunities for the public to 

participate. Public scoping meetings were held in 

March 2005 in the communities of Claremont, 

Diamond Bar, Downey, Rosemead, and Acton. The 

NPS published the results of the public scoping 

process in a second newsletter. 

In early 2006, the NPS refi ned the study area to 

add portions of the Rio Hondo River watershed 

and to remove cities within the Gateway Cities 

Council of Governments jurisdiction. In addition, 

the NPS revised the study scope to directly address 

concerns about potential impacts on local land use 

control and agency authorities. The NPS committed 

to producing a study that would respect property 

rights and the authorities that currently belong to 

existing local, state, and federal agencies. The NPS 

continued to consult with public land management 

agencies and elected offi cials throughout the study 

process. 

Between 2006 and 2008, the NPS analyzed 

resources and developed preliminary alternatives. 

The NPS worked with local agencies and resource 

experts in analyzing the signifi cance of the study 

area resources. In 2007-2008, the NPS worked 

on development of the preliminary alternatives, 

consulting with other recreation and land 

conservation agencies within the study area. More 

information about outreach efforts during this time 

period is included in Chapter 8 of the study report, 

Consultation and Coordination. 

In fall of 2009, the NPS released draft alternatives 

for public review and comment in a fourth 

newsletter. The study team produced and 

distributed over 3,000 newsletters to organizations 

and individuals on its mailing lists, partner agencies, 

and at public and stakeholder meetings. Between 
viii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

August and October 2009, the study team held 

six public meetings at locations throughout the 

study area including Diamond Bar, El Monte, 

Santa Clarita, Glendora, Palmdale, and Tujunga. 

In addition to the public meetings, the NPS study 

team held meetings with local, state and federal 

government agencies, organizations, communities, 

and Congressional offi ces. The NPS received 

approximately 4,800 comments. Additional 

stakeholder meetings were held with various 

agencies in early 2010 to address specifi c concerns. 

Publication, Review and Transmittal

Publication of the Draft San Gabriel Watershed and 

Mountains Special Resource Study will be followed 

by a public comment period. The NPS study team 

will then revise the report if needed, and transmit 

it to the Secretary of the Interior. The Secretary will 

transmit the report to Congress, along with the 

Secretary’s recommendation for the area.

Signifi cance

The National Park Service (NPS) uses four basic 

criteria to evaluate the national signifi cance of 

proposed areas. These criteria, listed in the National 

Park Service Management Policies, state that a 

resource is nationally signifi cant if it meets all of the 

following conditions:

• It is an outstanding example of a particular type 

of resource.

• It possesses exceptional value or quality in 

illustrating or interpreting the natural or cultural 

themes of our nation’s heritage.

• It offers superlative opportunities for public 

enjoyment, or for scientifi c study.

• It retains a high degree of integrity as a true, 

accurate, and relatively unspoiled example of a 

resource.

The NPS evaluates national signifi cance for cultural 

resources by applying the national historic landmarks 

(NHL) criteria contained in 36 CFR Part 65.

National Park Service professionals consult with 

subject matter experts, scholars, and scientists, in 

determining whether a study area is nationally 

signifi cant. Natural and cultural resource 

experts and scholars, locally and within the NPS, 

contributed expertise, research, and technical 

review of the statement of signifi cance. See 

Chapter 8, Consultation and Coordination, in the 

draft study report for more information on subject 

matter experts and their role in this portion of the 

study process.

Within the large and diverse landscape of the study 

area, two regions were found to be nationally 

signifi cant: the San Gabriel Mountains and the 

Puente-Chino Hills. Because these regions have 

not been as heavily urbanized as the lowland 

valleys and fl oodplains of the study area, they 

are outstanding examples of the native southern 

California landscape. The San Gabriel Mountains 

are also culturally rich, with a long history of human 

use. Nationally signifi cant cultural resources in the 

San Gabriel Mountains include the Mount Wilson 

Observatory and the San Dimas Experimental 

Forest.

There are signifi cant resources in other portions of 

the study area. However, these resources are highly 

fragmented and surrounding development has, in 

many cases, negatively impacted their integrity.

San Gabriel Mountains

The San Gabriel Mountains and foothills are 

nationally signifi cant for their geologic resources, 

high biodiversity, dynamic river systems, and the 

long history of scientifi c study and discovery. 

Early conservation of the San Gabriel Mountains 

ensured that these areas were protected from rapid 

urbanization, which began in the late 19th century. 

Within a short distance, the mountains and foothills 

feature coastal, desert, montane, and sub-alpine 

ecological communities. This diverse landscape 

provides habitat for an abundance of rare and 

endemic plants and wildlife. In addition, the San 

Gabriel Mountains contain signifi cant waterways 

and riparian areas, some of which are eligible 

National Wild and Scenic River segments. Nationally 

signifi cant cultural resources include the San Dimas 

Experimental Forest, which contains some of the 

earliest and most comprehensively and continuously 

monitored research watersheds, and the Mount 

Wilson Observatory, which includes large telescopes 

that were used in signifi cant astronomical 

discoveries.

MOUNTAIN BUILDING AND DIVERSE GEOLOGY

• The San Gabriel Mountains are among the 

fastest growing mountains in the world. Forces 

from the San Andreas Fault to the north and 

a series of thrust faults on their south face are 

causing the San Gabriel Mountains to rise as 

much as 2 inches a year. This distinction makes 

the San Gabriel Mountains an excellent location 

to research or study mountain-building.

• Among the most geologically diverse ranges in 

Southern California, the San Gabriel Mountains 

are comprised of rock units from all the major 

geologic eras. The San Gabriel Mountains 
 Executive Summary Suitability ix

contain the most extensive, best-exposed, and 

most completely studied exposures of several 

geologic formations including the San Gabriel 

Mountains anorthosite massif, the Mount Lowe 

plutonic suite, and Pelona schist. Some of the 

oldest rocks (over one billion years old) on the 

west coast of the United States are located in 

the San Gabriel Mountains. 

• There is a long history of scientifi c study of 

the San Andreas Fault in southern California. 

Several historically signifi cant geologic 

discoveries occurred in the San Gabriel 

Mountains. 

• The dramatic change in elevation from sea level 

to 10,000 feet, coupled with striking landforms 

such as the Devil’s Punchbowl, makes for a 

highly scenic landscape of contrasts.

HIGH LEVELS OF BIODIVERSITY

• The topographically and geologically diverse 

mountains contain high levels of biodiversity. 

The plant communities in the San Gabriel 

Mountains provide habitat for 67 plant species 

and 105 wildlife species considered sensitive, 

rare, threatened or endangered. 

• Outstanding examples of rare southern 

California ecological communities in the San 

Gabriel Mountains and foothills include: alluvial 

fan sage scrub, bigcone Douglas-fi r, coastal 

sage scrub, relict juniper communities, riparian 

areas, and subalpine habitat. 

DYNAMIC RIVER SYSTEMS

• River systems within the San Gabriel Mountains 

meet the eligibility criteria for National Wild 

and Scenic River designation. Free-fl owing 

sections of Little Rock Creek and the North, 

East, and West forks of the San Gabriel River 

retain high levels of integrity and support 

sensitive wildlife.

• Some of the best remaining alluvial fan sage 

scrub vegetation in the Los Angeles Basin is 

found within the study area.

• The San Gabriel Mountains are among one 

of the richest areas for freshwater fi shes in 

southern California. 

SCIENTIFIC RESEARCH AND DISCOVERY

• Data collected in the San Dimas Experimental 

Forest since 1933 represents some of the 

earliest and most comprehensive records from 

continuously monitored U.S. Forest Service 

experimental watersheds in the United States. 

In 1976, the United Nations Educational, 

Scientifi c and Cultural Organization’s (UNESCO) 

Man and the Biosphere Program recognized the 

San Dimas Experimental Forest as a “Biosphere 

Reserve.” The San Dimas Experimental Forest 

contains structures that are excellent examples 

of Forest Service architecture constructed 

and maintained through Depression-era relief 

programs, as well as a lysimeter facility that is 

the largest structure of its type ever built.

• The Mount Wilson Observatory, established 

in 1904, includes fi ve signifi cant telescopes 

that laid the technological foundation for all 

large modern telescopes. Many of the major 

advances, such as the Big Bang theory and the 

greatest names in 20th-century astronomy, are 

associated with the observatory. 

Puente-Chino Hills

The Puente-Chino Hills in the Los Angeles basin 

contain rare native plant communities. Although 

this area is somewhat of an island of open space 

surrounded by urbanized areas, the PuenteChino Hills and the Santa Ana Mountains to the 

southeast together encompass about 500,000 

acres of wildlands containing signifi cant biological 

resources. 

HIGH LEVELS OF BIODIVERSITY

• The Puente-Chino Hills are part of a biologically 

diverse regional wildlife corridor that provides 

habitat for ecological communities with an 

abundance of endemic, threatened, and rare 

plants and animals. 

• Outstanding examples of southern California 

communities in the Puente-Chino Hills 

include coastal sage scrub, one of the most 

endangered plant communities in California, 

and the best remaining stands of California 

walnut-dominated forests and woodlands 

south of Ventura County. 
x Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Suitability 

To be considered suitable for addition to the 

national park system, an area must represent a 

natural or cultural resource type that is not already 

adequately represented in the national park system, 

or is not comparably represented and protected for 

public enjoyment by other federal agencies; tribal, 

state, or local governments; or the private sector. 

The National Park Service determined that the San 

Gabriel Mountains and Puente-Chino Hills portions 

of the study area are suitable for inclusion in the 

national park system, based upon evaluation of 

the study area resources and their relative quality, 

character, and rarity. Together, the San Gabriel 

Mountains and Puente-Chino Hills contain a 

combination of themes and resources not found 

in any national park unit or comparably managed 

area. 

San Gabriel Mountains 

The overall combination of cultural and natural 

resource values and themes represented by the 

San Gabriel Mountains is not comparable to any 

other national park unit or comparably managed 

areas. Represented within these themes are 

unique geological features and dramatic geologic 

processes, a wide diversity of rare habitats located 

in close proximity given the dramatic changes in 

topography, and technological advances in the 

areas of astronomy, chaparral ecosystems, and 

watersheds. 

The close proximity of the San Gabriel Mountains to 

urban areas of the Los Angeles region means that 

this area has excellent potential for interpretation, 

education, and continued scientifi c study.

Puente-Chino Hills

The Puente-Chino Hills have resources that are 

outstanding representations of habitat types 

not widely found in other national park units or 

comparably managed sites. Represented within 

these themes are coastal sage scrub habitat and 

California walnut woodlands, both of which 

support rare and endangered plants and wildlife. 

Although coastal sage scrub is protected at several 

national park units, no other existing national 

park unit or comparably managed area protects a 

signifi cant amount of the rare California walnut 

woodlands. Protected status for the Puente-Chino 

Hills within the study area would expand and 

enhance existing resource protection and ensure 

long term conservation of the larger Puente-Chino 

Hills corridor.

Located in close proximity to urban populations of 

the Los Angeles basin, universities and colleges, the 

Puente-Chino Hills provide excellent opportunities 

for interpretation, education, and scientifi c study. 

Puente Hills and the San Gabriel Mountains. 2006. Photo by Bruce Perry, Department of Geological Sciences, CSU Long Beach.
 Executive Summary Feasibility xi

Feasibility 

To be feasible as a new unit of the national park 

system, an area must be: (1) of suffi cient size and 

appropriate confi guration to ensure sustainable 

resource protection and visitor enjoyment (taking 

into account current and potential impacts from 

sources beyond proposed park boundaries), and (2) 

capable of effi cient administration by the National 

Park Service at a reasonable cost. In evaluating 

feasibility, the NPS considers a variety of factors for 

a study area, such as the following:

• size

• boundary confi gurations

• current and potential uses of the study area 

and surrounding lands

• landownership patterns

• public enjoyment potential

• costs associated with acquisition, development, 

restoration, and operation

• access

• current and potential threats to the resources

• existing degradation of resources

• staffi ng requirements

• local planning and zoning

• the level of local and general public support 

(including landowners)

• the economic/socioeconomic impacts of 

designation as a unit of the national park 

system

The feasibility evaluation also considers the ability 

of the NPS to undertake new management 

responsibilities in light of current and projected 

availability of funding and personnel.

The NPS fi nds that a collaborative partnershipbased park unit is feasible, as one that respects 

the complex mix of land use, ownership, and 

regulatory authority in the study area. Opportunities 

for collaborative management with local, state 

and federal managers to protect natural and 

cultural resources, provide recreation, public access, 

interpretation and educational opportunities, and 

other compatible uses in an NPS partnership-based 

park unit have been demonstrated to exist. A large 

traditional national park unit, owned and operated 

solely by the National Park Service is determined to 

be infeasible, based on the complexity of existing 

land use and ownership patterns.

Need for NPS Management 

The need for direct NPS management is the fi nal 

criterion for a favorable recommendation for a 

proposed unit of the National Park System. The 

criterion requires a fi nding that NPS management 

would be superior to other potential alternative 

management arrangements by other entities. 

The NPS fi nds that a collaborative-based 

management approach which includes a leadership 

role for the National Park Service is a superior 

management option for meeting the complex 

conservation and recreation needs of the study 

area. 

Photos (top to bottom): 1. West Fork Trail, Angeles 

National Forest. NPS photo. 2. Devil’s Punchbowl. San 

Gabriel Mountains. 2006. NPS photo. 
xii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Alternatives

Four management alternatives are evaluated in 

this special resource study. One alternative is the 

“no action” alternative which serves as a baseline 

of existing conditions. Alternatives A, C, and D, 

the action alternatives, emphasize cooperative 

management of existing public lands and 

federal designation of a national recreation area. 

Alternative B, San Gabriel Parks and Open Space 

Network, was dismissed from further consideration 

after public review of the preliminary alternatives 

in 2009 (Newsletter 4). Some components of 

alternative B were incorporated into alternative D.

The three action alternatives do not propose large 

federal land acquisitions as the majority of the 

land is already owned and managed by the U.S. 

Forest Service and other public recreation and 

conservation agencies. Each action alternative seeks 

to enhance the capabilities of existing agencies 

by leveraging resources, sharing information, and 

through cooperative planning and administration. 

Through the scoping process, numerous 

stakeholders including public agencies, citizens, 

organizations, and elected offi cials, identifi ed 

specifi c issues and concerns that should be 

considered in the study process. Based on this 

input, issue statements were developed by the 

study team to describe the context for this study. 

The alternatives explore various approaches to 

addressing the issues identifi ed:

• Additional funding is needed to meet resource 

protection and recreation objectives.

• There are suffi cient barriers to outdoor 

recreation for some communities including lack 

of close-to-home recreational opportunities, 

poor access to recreational areas, and personal 

safety concerns.

• The Los Angeles region continues to experience 

tremendous population growth causing 

increasing demands on existing recreation 

areas.

• Greater protection is needed for the region’s 

rare and threatened ecological communities.

• The study area’s cultural resources would 

benefi t from further documentation, 

protection, and/or interpretation.

• The study area lacks a clear sense of identity

that could help connect communities to the 

natural and cultural resources of the San 

Gabriel Mountains and the Puente-Chino Hills.

• The region’s natural, cultural, and recreational 

resources lack a comprehensive management 

plan and could benefi t from a regional planning 

structure.

• There is an ongoing need to protect and restore 

riparian ecosystems and provide appropriate 

recreational use of waterways while improving 

water quality, enhancing effi ciency of 

water storage and use, and providing fl ood 

protection.

Santa Fe Dam Recreation Area. 2004. NPS photo. 
 Executive Summary Feasibility xiii

Items Common to All Action 

Alternatives 

A PARTNERSHIP APPROACH

The National Park Service recognizes that many 

other public agencies, private conservation 

organizations, and individuals successfully manage 

important natural and cultural resources and 

recreational opportunities within the study area. 

The NPS applauds these accomplishments and 

actively encourages the expansion of conservation 

activities by state, local, and private entities and by 

other federal agencies. The alternatives presented 

retain existing management and build on existing 

efforts by suggesting new partnerships, funding 

sources, and technical assistance opportunities. 

U.S. FOREST SERVICE MANAGEMENT

U.S. Forest Service management and ownership 

of existing Angeles National Forest lands would 

be maintained in all of the alternatives. U.S. Forest 

Service policies would continue to be applied to 

management of these lands. 

NATIONAL RECREATION AREA (NRA)

Each of the three action alternatives proposes a 

national recreation area designation to increase 

the capacity to protect signifi cant resources and 

to provide improved recreational opportunities for 

the region. Two of the national recreation area 

alternatives would include the establishment of a 

national park unit to be managed in partnership 

with existing agencies. The other would be a U.S. 

Forest Service national recreation area applied to 

existing Angeles National Forest lands. The NPS 

would have no role in that alternative (alternative 

A).

RETENTION OF LOCAL LAND USE AND 

EXISTING REGULATORY AUTHORITIES

The designation of a NPS national recreation area 

would not establish additional regulatory or land 

use authorities over local governments. The NPS 

is not a regulatory agency. NPS land management 

policies and regulations would only apply to lands 

that the NPS acquires. The NPS would only consider 

acquiring land on a limited basis from willing sellers. 

All of the alternatives would respect existing 

general plans and local zoning, as well as state 

and local laws and policies for lands that are not 

federally owned.

PROTECTION OF WATER SUPPLY, 

FLOOD PROTECTION, AND SANITATION 

INFRASTRUCTURE FACILITIES AND FUNCTIONS

The Los Angeles metropolitan region has highly 

complex systems of public infrastructure to 

transport and store local and regional water 

supplies. In addition, numerous facilities are 

necessary to treat wastewater and manage solid 

waste. No alternative presented would change 

existing water rights, water supply operations, 

water treatment operations, fl ood protection 

efforts, or other agency functions necessary to 

maintaining public infrastructure essential for public 

health and safety. 

All the proposed alternatives would retain existing 

and future water rights. Management of water 

supply and treatment plants would continue under 

current authorities. The NRA designation would 

not entail any new or future benefi cial uses or 

requirements for water supply, water quality, or air 

quality regulations.

This study recommends that any resulting 

legislation ensure that existing sanitation facilities 

and operations such as landfi lls and water 

treatment plants would continue to be operated 

and regulated by existing agencies and would not 

be affected by the NRA designation.

PRIVATE PROPERTY RIGHTS

Any legislation proposed to implement this study 

should specify that eminent domain would not be 

used for land acquisition within the NRA. The NPS 

would only consider acquiring land on a limited 

basis from willing sellers. Designation would not 

impact local land use authority over lands not 

owned by the NPS.

FIRE PROTECTION

Fire protection would remain the responsibility 

of existing federal, state, and local agencies (Los 

Angeles County, U.S. Forest Service, California 

Department of Forestry and Fire Protection). The 

NRA partnership could work together to take 

a pro-active approach to coordinated resource 

management to reduce catastrophic fi res.
xiv Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

No Action Alternative: Continuation 

of Current Management 

CONCEPT

The no action alternative is required by the National 

Environmental Policy Act (NEPA) to provide a 

baseline with which to compare action alternatives. 

Under this alternative, the NPS would have no role 

in the study area beyond the existing national park 

units (segments of two national historic trails), and 

existing fi nancial and technical assistance programs 

such as the Land and Water Conservation Fund 

grant program, the Rivers, Trails and Conservation 

Assistance Program, the National Historic Landmark 

program, and the Route 66 corridor program. This 

alternative assumes that current programs and 

policies of existing federal, state, county, and nonprofi t conservation organizations would continue 

at existing levels and current conditions and trends 

would continue. 

MANAGEMENT

Existing cooperative management efforts between 

agencies would continue. Current efforts to protect 

wildlife corridors and provide new recreational 

opportunities would continue to occur on a caseby-case basis as existing funding allows.

Public land management agencies would continue 

their land management, visitor services, public 

education, and interpretation programs at 

approximately the current levels of activity and 

funding, according to current plans. 

Cities and unincorporated areas would continue 

to conserve open space and provide recreational 

opportunities where possible. Local agencies would 

continue to provide services as funding allows. 

Coordination and communication between local 

governments would continue to occur on a caseby-case basis.

Non-profi t conservation activities would continue at 

current levels.

EDUCATION AND INTERPRETATION

Existing national forest lands, national historic 

landmarks, museums, visitor centers, parks, and 

other sites owned by state and local agencies 

and nonprofi t organizations would continue to 

be interpreted as they are today. Existing national 

park units would continue to provide interpretation 

and education opportunities. Improvements in 

interpretive programs and media may occur as 

funding becomes available. Coordinated efforts 

to interpret the signifi cant resources of the San 

Gabriel Watershed and Mountains would not occur. 

Education and interpretation efforts would continue 

to occur on a project-by-project basis. 

RECREATIONAL OPPORTUNITIES AND ACCESS

New recreational opportunities and access would 

occur through existing agencies, organizations, and 

governments as funding permits. 

RESOURCE PROTECTION (ECOLOGICAL 

COMMUNITIES AND CULTURAL RESOURCES)

Protection of natural and cultural resources under 

the management of existing agencies would 

continue. Government grant programs, California 

state land conservancies, local governments, and 

non-profi t land conservancies/trusts throughout 

the study area would continue to conserve and 

restore native ecosystems and habitat. It is assumed 

that these efforts would continue at current levels. 

Existing planning efforts to link habitat connections 

such as the South Coast Missing Linkages Project 

would continue. Implementation would be the 

responsibility of existing agencies and landowners. 

OPERATIONS AND MAINTENANCE

Operations and maintenance of existing parks 

and open space would be assumed to remain at 

current levels. For some agencies, more resources 

are available for the acquisition of lands than are 

available for operations and management.

Whittier Narrows Recreation Area. NPS photo. 
 Executive Summary Feasibility xv

Alternative A: San Gabriel 

Mountains National Recreation 

Area: A U.S. Forest Service 

Designation

CONCEPT

Congress would designate the San Gabriel 

Mountains unit of the Angeles National Forest (ANF) 

as a U.S. Forest Service National Recreation Area 

(NRA) that would continue to be managed solely by 

the U.S. Forest Service. The designation would bring 

additional recognition, tools, and resources to the 

ANF in order to steward watershed resources and 

ecosystems, and improve recreational opportunities.

Legislation establishing the NRA would reaffi rm 

the primary importance of the ANF in preserving 

watershed and natural resources and emphasize 

future management practices that are compatible 

with resource protection. Authorizing legislation 

would also recognize the importance of the NRA 

for its recreational value and establish mechanisms 

to increase funding for facilities, maintenance, 

ecological restoration, visitor management, 

educational programming, and stewardship 

activities.

No unit of the national park system would be 

established.

PROPOSED AREA

The NRA would encompass the existing Angeles 

National Forest lands associated with the San 

Gabriel Mountains.

MANAGEMENT

The U.S. Forest Service would continue to manage 

the NRA according to existing management policies. 

The legislation establishing the NRA would provide 

the ANF with new authorities that would allow the 

U.S. Forest Service to partner with organizations to 

provide additional resources for recreation, resource 

protection, maintenance, and safety.

NPS Role

No unit of the national park system would be 

established. Existing units of the NPS would 

continue current management. The Santa Monica 

Mountains National Recreation Area would continue 

to partner with the U.S. Forest Service, as it currently 

does, on an informal basis. The NPS would continue 

to provide technical and fi nancial assistance to local 

communities through existing programs.

Antelope Valley. 2007. NPS Photo.
xvi Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Existing Agencies and Authorities

The designation would only apply to lands currently 

owned and managed by the U.S. Forest Service. 

Private lands and inholdings would continue to be 

regulated by local land use authorities.

EDUCATION AND INTERPRETATION

The Angeles National Forest would be recognized 

for its nationally signifi cant resources associated 

with the San Gabriel Mountains. New partnership 

efforts and additional funding for education and 

interpretation staff would allow for interpretive 

media and programs within the ANF.

The NRA could explore new opportunities for 

education and research associated with the San 

Dimas Experimental Forest.

RECREATIONAL OPPORTUNITIES AND ACCESS

Existing recreational opportunities would remain 

on the Angeles National Forest. New partnership 

opportunities may assist the Angeles National Forest 

in fundraising for improved recreational experiences 

and planning for recreational connections. 

Enhanced recreational experiences would include 

improved visitor management in heavily used 

recreational areas as a result of more forest rangers, 

better facilities, improved trail connections and 

trailheads, and new educational and interpretive 

efforts. 

RESOURCE PROTECTION (ECOLOGICAL 

COMMUNITIES AND CULTURAL RESOURCES)

The U.S. Forest Service would continue balancing 

use and resource protection in accordance with 

its multiple-use policy. The authorizing legislation 

would direct that any proposed new uses would 

need to be compatible with protecting watershed 

and signifi cant resources.

The NRA would bring additional recognition, tools, 

and resources to the ANF in order to steward 

signifi cant resources associated with the San 

Gabriel Mountains. Legislation would authorize 

the U.S. Forest Service to enter into cooperative 

management agreements with other agencies 

to protect habitat and ecosystems that cross 

jurisdictional boundaries. Ecological restoration 

would be emphasized.

New resources would be allocated to document, 

protect, and interpret cultural resources in the San 

Gabriel Mountains. 

OPERATIONS AND MAINTENANCE

Authorizing legislation would direct additional 

funding for operations and maintenance of the 

NRA allowing the ANF to provide more rangers 

and other staff in heavily used visitor areas. New 

volunteer programs would be developed to assist 

in the maintenance of facilities, preservation/

restoration efforts, and interpretation of signifi cant 

resources.

The NRA would also have dedicated staff to 

coordinate new partnerships and volunteer efforts. 

FUNDING AND COSTS

In order to accomplish the goals of the NRA, 

substantial additional funding would be required, 

either through appropriations, partnerships, or 

philanthropy. 

Legislation could allow the forest to receive direct 

donations and provide a mechanism for establishing 

a nonprofi t fundraising or “friends of the forest” 

group. The elevated visibility and attention of a new 

designation, coupled with an increased sense of 

identity for the area’s signifi cant resources, would 

enhance the ability of the ANF to raise private 

funds and seek special appropriations for particular 

projects. 

Eaton Falls. Photo by Eric Lowenbach. 
 Executive Summary Feasibility xvii

Alternative C: San Gabriel 

Watershed National Recreation Area

CONCEPT

Alternative C proposes a river-based national 

recreation area (NRA) that would serve to raise the 

visibility of the San Gabriel River watershed, offer 

new educational and interpretive opportunities 

throughout the watershed, and improve existing 

river-based recreation. 

The NRA would be established by an act of 

Congress, which would provide the U.S. Forest 

Service, the NPS, and other land management 

agencies and organizations with guidance and 

direction to collaborate in protecting signifi cant 

resources, providing new recreational opportunities, 

and improving visitor use of existing recreation 

areas. 

Very little land would need to be acquired for 

direct management by the National Park Service. 

Instead, partnership arrangements among federal 

and state agencies, local governments, non-profi t 

organizations, and area landowners would achieve 

the conservation, recreational, and educational 

goals of the NRA.

PROPOSED AREA

The NRA would encompass the upper San Gabriel 

River Watershed within the Angeles National Forest 

and a half-mile corridor around the San Gabriel 

and Rio Hondo Rivers, south to Santa Fe Springs. 

This is the same corridor width used for the San 

Gabriel River Master Plan. The NRA would include 

approximately 178,000 acres of land; 89% of this 

area is already protected by existing agencies and 

organizations.

MANAGEMENT

NRA Partnership

The NRA would be managed by a voluntary 

partnership that would include agencies and 

organizations with land and interests in the area. 

In existing public land areas, inter-agency 

agreements could augment agency staffi ng to 

manage highly used areas such as the San Gabriel 

Canyon, providing higher levels of visitor services, 

education, and safety.

The NRA would partner with existing environmental 

education centers, school districts, visitor centers, 

and youth organizations to provide ranger 

programs and opportunities to engage children 

and residents of all ages in learning about 

environmental stewardship and the natural and 

cultural signifi cance of the San Gabriel River 

Watershed.

NPS Role

The primary role of the NPS would be: 1) 

coordinating the formal partnership that would 

manage activities within the NRA, and 2) providing 

interpretation and education. The NPS would 

also take the lead in coordinating a voluntary 

information network throughout the San Gabriel 

Watershed to provide interpretive and educational 

messages about signifi cant resources. 

Through cooperative management agreements, 

the NPS could provide assistance to partner 

agencies with visitor management and protection, 

interpretation and education. The NPS would also 

have a lead role in coordinating interpretative and 

educational messages about signifi cant resources.

Existing Agencies and Authorities

The designation of the NRA would not apply 

additional regulatory or land use authorities 

over existing agencies or local governments. 

Each partner and jurisdiction would retain land 

ownership, management, and decision-making 

authorities for lands that they own. NPS land 

management policies and regulations would only 

apply to lands that the NPS acquires. Privately-held 

lands would continue to be regulated by local land 

use authorities.

EDUCATION AND INTERPRETATION

The NRA would partner with existing environmental 

education centers, school districts, visitor centers, 

and youth organizations to provide ranger 

programs and opportunities to engage children 

and residents of all ages in learning about 

environmental stewardship and the natural and 

cultural signifi cance of the San Gabriel River 

Watershed.

The NRA partnership would provide interpretive 

programs at existing recreation areas, schools, 

interpretive centers, and historical sites/areas 

within the NRA. The NRA partnership would also 

coordinate a voluntary, shared information network 

in which sites within the San Gabriel Watershed 

would deliver coordinated interpretive messages 

about the watershed.

RECREATIONAL OPPORTUNITIES AND ACCESS

Recreational uses and activities would be 

determined by the existing land management 

agency. The NRA partners would work together 

to improve and enhance the quality of existing 
xviii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

recreational experiences through facility 

improvement, additional staff (rangers and 

interpreters), monitoring efforts, and cooperative 

planning.

Within the NRA, the partnership would work to 

foster new recreational opportunities that are 

compatible with maintaining watershed values, 

water supply, fl ood protection, and habitat values. 

The NRA partnership would explore opportunities 

for improved transportation and trail connections to 

destinations within the NRA.

RESOURCE PROTECTION 

The NRA partnership would seek additional 

funding for resource protection and would 

facilitate opportunities to work collaboratively to 

conserve and enhance resources along the San 

Gabriel River and its upper watershed through 

research, cooperative management, and ecological 

restoration. New resources would be allocated to 

document, protect, and interpret cultural resources 

within the NRA. 

OPERATIONS AND MAINTENANCE

Existing agencies would continue to be responsible 

for the operation and maintenance of their lands 

and facilities. Through cooperative management 

agreements, the NRA agency partners would be 

able to share staff, facilities, and funding to assist 

in the operations and maintenance of heavily 

used visitor areas. The NPS would coordinate new 

partnerships and facilitate the development of more 

volunteer programs to assist in the maintenance 

of facilities, preservation/restoration efforts, and 

interpretation of signifi cant resources. 

The NPS would require funding for staff including 

administration, interpreters, planners, law 

enforcement, outreach coordinator, education 

specialists, and resource management specialists. 

Job training programs could be incorporated into 

staffi ng and volunteer programs. Given NPS budget 

constraints, it is likely that the NRA would initially 

have a small staff that would increase over time 

as funding is available. A general management 

plan would identify park priorities, management 

emphases, and required staffi ng for a 15-20 year 

timeframe. 

The NPS would share offi ce space with partner 

agencies or lease offi ce space in or near the NRA 

for operations and administration. The NPS could 

also seek use of existing buildings for visitor serving 

facilities. Specifi c operational and visitor facility 

needs would be identifi ed through a general 

management plan.

Land Acquisition

The majority of land within the NRA is owned and 

managed by public agencies. Lands within the NRA 

would remain under their current ownership and 

jurisdictions, with each land management agency 

continuing to fund its own operations. The need 

for land acquisition by the NPS would be small, 

targeted for protection of signifi cant resources, 

and subject to available funding. Partner agencies 

would also contribute funds for land acquisition 

within the NRA.

COSTS AND FUNDING

The NPS would receive federal funding for its 

administrative, educational, technical assistance, 

and interpretive roles. Based on the size of the area, 

and the types of services and assistance offered, the 

NPS budget for the NRA might fall between $1 to 

$3 million. The NRA designation may also enhance 

funding or fundraising opportunities for the U.S. 

Forest Service.

The NRA partnership would be a coordinating 

body for existing grant programs, and could work 

together to leverage funds from a variety of sources 

(e.g. state bonds, Land & Water Conservation Fund) 

to increase funding for projects in the NRA. 

Bigcone Douglas fi r. Photo courtesy of BonTerra Consulting.
 Executive Summary Feasibility xix

Alternative D: San Gabriel Region 

National Recreation Area (A 

Partnership Linking Signifi cant 

Resources and Recreation)

CONCEPT

Alternative D represents a combination of ideas 

from the preliminary alternatives that were 

presented to the public in fall 2009. Alternative 

D proposes a larger scale national recreation 

area (NRA) that would recognize and protect the 

signifi cant resources associated with the San Gabriel 

Mountains and Puente Hills, explore opportunities 

to protect and enhance interconnected ecosystems, 

provide important open space connections 

for recreation, and offer new educational and 

interpretive opportunities. Ecological restoration 

would be emphasized.

The management approach of alternative D 

would be the same as alternative C. The NPS, U.S. 

Forest Service, and numerous other agencies and 

organizations with land and interests in the area 

would work collaboratively to protect signifi cant 

resources and improve recreational opportunities. 

Very little land would be need to be acquired for 

direct management by the NPS.

Unlike the other alternatives, in Alternative D the 

NPS and the partnership would offer technical 

assistance to willing surrounding communities 

for conservation planning to extend open space 

connections and form a network of parks, habitats, 

and open spaces.

PROPOSED AREA

Alternative D proposes the largest NRA of the three 

action alternatives, providing more opportunities for 

resource protection, inter-agency coordination, and 

recreation. The NRA would include the San Gabriel 

Mountains, portions of the San Gabriel and Rio 

Hondo Rivers, and a portion of the western Puente 

Hills. 

Within the San Gabriel Mountains, the NRA would 

include the Angeles National Forest (ANF) adjacent 

foothill areas with ecological resource values, 

and areas near the San Andreas Fault. Areas with 

ecological resource values include designated 

critical habitat for federally listed threatened or 

endangered species, and/or areas within one of the 

Los Angeles County proposed signifi cant ecological 

areas. Below the ANF, the NRA would include a 

half-mile corridor around the San Gabriel and Rio 

Hondo rivers corridors, south to Santa Fe Springs. 

Portions of the western Puente Hills with ecological 

resource value and recreational potential (areas 

west of Harbor Boulevard) would also be included. 

This primarily includes lands owned and managed 

by the Puente Hills Landfi ll Native Habitat Authority 

and lands proposed by Los Angeles County to be 

included in the Puente Hills Signifi cant Ecological 

Area.

MANAGEMENT

NRA Partnership

The management structure of alternative D 

would primarily be the same as alternative C, but 

with some broader functions. The NPS and the 

partnership would offer conservation planning 

assistance to interested communities to extend 

open space connections and form a network of 

parks, habitats, and open spaces. 

In the more urban areas associated with the river 

corridors, the NRA partnership would work with 

interested surrounding communities to increase the 

amount and variety of public open space, parks 

and recreational lands, particularly in under-served 

areas, and to enhance public transportation access 

between urban populations and the public lands of 

the NRA.

In rural areas such as Soledad Basin, Antelope 

Valley, or Mt. Baldy, where future growth pressures 

may threaten open space and the rural quality 

of life, the NRA would work with communities 

to preserve additional open space and improve 

recreational trail connections and staging areas. 

In existing public land areas, interagency 

agreements could augment agency staffi ng to 

manage highly used areas such as the San Gabriel 

Canyon, providing higher levels of visitor services, 

education, and safety.

NPS Role

The NPS role in alternative D would primarily 

be same as alternative C, but with the addition 

of a technical assistance program to provide 

conservation and recreation planning to interested 

public agencies, private landowners, and 

organizations beyond the NRA boundaries to create 

and connect parks, conserve habitat, and provide 

new recreational experiences.

Existing Agencies and Authorities

The designation of the San Gabriel Region NRA 

would not apply additional regulatory or land 

use authorities over existing agencies or local 

governments. Each partner and jurisdiction would 

retain landownership, management, and decisionmaking authorities for lands that they own. 
xx Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

NPS land management policies and regulations 

would only apply to lands that the NPS acquires. 

Private lands would continue to be regulated by 

local land use authorities.

EDUCATION AND INTERPRETATION

Educational and interpretive programming would 

primarily be the same as alternative C, except that 

with a larger NRA in alternative D, a wider array of 

interpretive topics and themes, as well as on-site 

interpretive and educational programming, would 

occur throughout the San Gabriel Mountains, along 

the San Gabriel River, and in the Puente-Chino Hills.

RECREATIONAL OPPORTUNITIES AND ACCESS

EDUCATION AND INTERPRETATION

Within the NRA, a variety of recreational 

opportunities would be available to the public. 

Allowable recreational uses and activities would 

continue be determined by the existing land 

management agency. In alternative D, the NRA 

partnership would seek to improve recreational 

access and opportunities in urban areas that 

are defi cient in recreation and park lands by 

offering assistance in planning for close-to-home 

recreational opportunities, better trail access, 

and improved public transportation options to 

recreational areas. Additionally, the partnership 

would explore opportunities to restore vacant 

or unused land to provide new recreational 

opportunities.

RESOURCE PROTECTION 

The NRA partnership would facilitate opportunities 

to work in collaboration with partner agencies 

to conserve and enhance signifi cant resources 

associated with the San Gabriel Mountains, 

watershed, and the Puente Hills through research, 

cooperative management, and ecological 

restoration. 

The NRA partnership would seek to leverage 

additional funding for wildlife and habitat 

management and offer conservation technical 

assistance when requested. Coordinated cultural 

resource management would be the same as in 

alternative C, but would cover a broader area. 

OPERATIONS AND MAINTENANCE

Existing agencies would continue to be responsible 

for the operation and maintenance of their lands 

and facilities. Through cooperative management 

agreements, the NRA agency partners would be 

able to share staff, facilities, and funding to assist 

in the operations and maintenance of heavily 

used visitor areas. The NPS would coordinate new 

partnerships and facilitate the development of more 

volunteer programs to assist in the maintenance 

of facilities, preservation/restoration efforts, and 

interpretation of signifi cant resources.

Required NPS staff for the NRA would be similar to 

alternative C. However, with a larger land area and 

a broader set of programs, alternative D would be 

expected to require slightly higher staffi ng levels.

Job training programs could be incorporated into 

staffi ng and volunteer programs.

The NPS would share offi ce space with partner 

agencies or lease offi ce space in or near the NRA 

for operations and administration. The NPS could 

also seek use of existing buildings for visitor serving 

facilities. Specifi c operational and visitor facility 

needs would be identifi ed through a general 

management plan.

Land Acquisition

The majority of land in the proposed NRA is owned 

and managed by public agencies. Lands within the 

NRA would remain under their current ownership 

and jurisdictions, with each land management 

agency continuing to fund its own operations. 

The need for NPS land acquisition would be small, 

targeted for protection of signifi cant resources, 

and subject to funding availability. Partner agencies 

would also contribute funds for land acquisition 

within the NRA when funding is available.

COSTS AND FUNDING

Costs and funding needs for alternative D would 

be similar to alternative C. However, a larger NRA 

would require more from the NPS in terms of 

its administrative, educational, and interpretive 

assistance to the partnership. The NPS budget for 

the NRA could be between $2 and $4 million based 

on analysis of comparable park units. 
 Executive Summary Environmental Assessment xxi

Environmental Assessment

Background

Before taking an action, the National Environmental 

Policy Act (NEPA) requires federal agencies to 

identify a range of alternatives for that action and 

to analyze the potential environmental impacts 

of that action, including any potential adverse 

environmental effects that cannot be avoided if the 

proposed action is implemented. The NPS prepared 

the environmental assessment (EA) for the Draft 

San Gabriel Watershed and Mountains Special 

Resource Study to identify and analyze the potential 

environmental and socioeconomic consequences of 

each of the alternatives considered in the study.

Impacts 

Consequences are determined by comparing likely 

future conditions under each alternative with 

the existing baseline conditions as described in 

the “no action” alternative. The analysis includes 

consideration of the context, intensity, and duration, 

of direct and indirect effects of all the alternatives. 

The NPS based analysis and conclusions on a review 

of existing literature, information provided by experts 

within the NPS, as well as outside organizations, 

analysis of case studies of existing programs in other 

locations, and the professional judgment of the study 

team members. 

The impact analysis for this study is necessarily 

broad to avoid speculation as to site-specifi c types 

of impacts given the broad nature of the study. The 

outcome of the study will be a recommendation 

to Congress. If Congress takes action, then new 

environmental analysis would be undertaken 

prior to specifi c implementation actions. This new 

analysis would propose specifi c actions, whose site 

or area specifi c impacts would be assessed prior to 

implementation of the plan. 

The NPS fi nds that there would be no signifi cants 

impacts associated with the proposed alternatives. 

The summary table which follows provides a 

summary of environmental consequences by specifi c 

impact topics.

Environmentally Preferred 

Alternative

The NPS is required to identify an “environmentally 

preferred alternative” in an EA. The environmentally 

preferred alternative is determined by applying 

criteria set forth in the National Environmental 

Policy Act, as guided by direction from the Council 

on Environmental Quality. 

The environmentally preferable alternative should 

not be viewed as the National Park Service’s 

preferred alternative. The Director of the National 

Park Service is required under law and policy 

to identify which alternative or combination of 

alternatives would be most effective and effi cient 

in protecting signifi cant resources and providing 

for visitor enjoyment. The Director will make this 

fi nding after the publication of the draft special 

resource study / environmental assessment, 

considering public and stakeholder comment. 

This fi nding will be included in the study package 

forwarded to the Secretary of the Interior. 

The environmentally preferred alternative is the 

alternative that: 

• Fulfi lls the responsibilities of each generation 

as trustee of the environment for succeeding 

generations. 

• Ensures for all Americans safe, healthful, 

productive, and esthetically and culturally pleasing 

surroundings. 

• Attains the widest range of benefi cial uses of the 

environment without degradation, risk of health 

San Gabriel Mountain dudleya. Photo courtesy of Gabi 

McLean.
xxii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

or safety, or other undesirable and unintended 

consequences. 

• Preserves important historic, cultural and natural 

aspects of our national heritage and maintain, 

wherever possible, an environment that supports 

diversity and variety of individual choice. 

• Achieves a balance between population and 

resource use that will permit high standards of 

living and a wide sharing of life’s amenities 

• Enhances the quality of renewable resources and 

approach the maximum attainable recycling of 

depletable resources. 

Based on the aforementioned criteria, the NPS has 

determined alternative D to be the environmentally 

preferable alternative. Alternative D best meets the 

NEPA criteria because it would protect natural and 

cultural resources over a larger area, provide greater 

opportunities relating to recreation and visitation, and 

foster a larger framework for cooperative management 

(as compared to alternatives A and C). 

Goals Analysis

The following summary describes impacts as they 

relate to the goals established for the alternatives 

and the specifi c impact topics required by law and 

policy. The goals were developed by the study team 

based on the public input received. They represent 

values that appeared to be shared by the majority 

of the respondents in the various public input 

opportunities throughout the study process. 

ADDRESS CURRENT AND FUTURE RECREATION 

AND OPEN SPACE NEEDS

All three action alternatives (A,C, and D) seek to 

address recreation and open space needs within the 

study area. Alternative A would primarily improve the 

quality of recreation within the San Gabriel Mountains 

portion of the ANF. However, it would do little to 

address the needs of nearby urban communities 

that are currently defi cient in parks and open space. 

Without addressing this need, increasing demands 

on the ANF to provide local recreational opportunities 

could diminish the visitor experience over time. 

Alternative C would provide more recreation and open 

space opportunities for communities along the San 

Gabriel River and improve the recreational experience 

in the highly used San Gabriel River Canyon. 

Alternative D would provide the greatest ability to 

address current and future recreation and open 

space needs. A larger area is included in the NRA and 

technical assistance programs would allow the NRA 

to assist local communities in making connections to 

NRA resources and in developing more close-to-home 

recreation. Alternative D would also provide more 

resources for regional open space conservation.

PROTECT OR RESTORE SIGNIFICANT NATURAL 

RESOURCES AND IMPORTANT HABITATS

Alternative A would provide improved protection 

of nationally signifi cant resources within the San 

Gabriel Mountains. Signifi cant native habitat would 

be improved by greater restoration efforts and 

improved planning and partnerships with other 

agencies to protect wildlife corridors. Alternative 

C would do the least in terms of protecting and 

restoring signifi cant natural resources and important 

habitats as it contains the smallest amount of 

nationally signifi cant resources and native habitat 

found within the study area. Restoration and 

protection would occur in the San Gabriel River 

upper watershed and along the river corridor to 

Santa Fe Springs. However, signifi cant resources 

located in other areas of the San Gabriel Mountains 

and Puente Hills would not benefi t. 

Alternative D provides the greatest opportunity to 

protect and restore natural resources and important 

habitats on a regional scale. The proposed NRA 

would contain most of the nationally signifi cant 

regions identifi ed in the resource analysis. 

Additionally, the NRA partnership would work 

regionally to protect and restore wildlife corridors 

and habitat. Studies have shown that protection of 

wildlife corridors enhances ecological diversity and 

provides protection from threats from nonnative 

species, altered fi re regimes, and the effects of 

climate change.

PRESERVE HISTORIC AND CULTURAL 

RESOURCES

Most of the nationally signifi cant cultural resources 

in the study area are located in the San Gabriel 

Mountains. As such, alternatives A and D provide 

the most potential for protecting signifi cant cultural 

resources within the study area. Alternative C would 

allow for greater preservation of cultural resources 

associated with the San Gabriel River, including 

historic mining sites, the site of the original San 

Gabriel Mission, and the Pio Pico State Historical 

Park. However, alternative C would preserve cultural 

resources to a lesser degree than alternatives A and 

D due to its narrower geographical focus. 
 Executive Summary Environmental Assessment xxiii

MAINTAIN OR IMPROVE WATER QUALITY, 

WATER CONSERVATION AND FLOOD 

PROTECTION

All of the alternatives would respect existing 

management and structures necessary for fl ood 

protection and water conservation. However, 

each of the action alternatives would have the 

potential to improve water quality. Alternative D 

would provide the most opportunities to improve 

water quality through improved visitor education, 

visitor management, and restoration opportunities 

throughout the San Gabriel Mountains and along 

the San Gabriel River. 

Alternative A would provide regional benefi ts 

to water quality and conservation. The early 

conservation of the San Gabriel Mountains was 

intended for watershed protection and this would 

be reaffi rmed in both Alternatives A and D. 

Protection of watershed resources and additional 

restoration throughout the mountains would 

improve water quality both in the mountains and 

downstream. Alternative C would have benefi ts to 

the San Gabriel River watershed, through enhanced 

visitor management and education and restoration 

opportunities within the NRA. However, it would 

do nothing to improve the water quality of other 

watersheds located within the study area, such as 

the Los Angeles River, the Santa Clara River, and 

rivers that drain into the Antelope Valley.

Day use activies, Angeles National Forest. NPS photo. 
xxiv Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Impact Topics No Action Alternative A

Biological 

Resources - Native 

Plants

Trends that currently have an adverse impact 

on native plants, such as invasive species, 

altered fi re regimes, and habitat loss, would 

continue to have minor to moderate adverse 

effects on native plant communities.

Protection and awareness of native 

plants through enhanced interpretation 

and educational efforts due to the new 

designation would have benefi cial effects on 

native plant communities. 

There would be opportunities for increased 

staff and funding dedicated to the control of 

nonnative species. 

The USFS would have additional authorities to 

work with other land management agencies 

to protect important wildlife connections 

to the forest. Protection of habitat corridors 

enhances species diversity and resilience to 

threats such as altered fi re regimes, invasive 

species, and climate change. 

Biological 

Resources 

- Wildlife

Many of the study area native habitat types 

are severely reduced from their former range. 

Threats such as habitat loss and 

fragmentation as a result of development, 

air pollution, water pollution, and altered fi re 

regimes would continue to have moderate 

adverse effects on the viability of many 

species and communities including those that 

are threatened or endangered. 

In alternative A, the proposed designation 

would bring more resources to the USFS for 

habitat restoration, conservation, research, 

and planning for wildlife corridors. 

Designation would ensure that proposed new 

or future uses on the national forest would be 

compatible with the protection of signifi cant 

resources and watershed values. This would 

have an overall benefi cial effect on protecting 

wildlife resources within the ANF.

Cultural Resources Trends that adversely impact cultural 

resources including, archeological and 

historical resources within the study area 

would continue. 

Within the ANF, cultural resources would 

continue to be threatened by erosion, fi re, 

fl ood, vandalism, looting, and land use 

practices. Additional threats to cultural 

resources throughout the study area include 

fl ooding, water erosion, off-road vehicle 

use, unauthorized collecting of artifacts, and 

industrial activities such as mining. 

Such threats would continue to have minor 

to moderate adverse effects on cultural 

resources.

In alternative A, more resources would be 

available to the USFS for documentation, 

education, and interpretation of cultural 

resources within the ANF. The ANF may also 

be better able to form new partnerships for 

the protection of cultural resources. 

Beyond the ANF, existing threats to cultural 

resources would continue to have minor to 

moderate adverse effects on cultural resources 

as a result of natural deterioration of some 

historic resources due to lack of maintenance 

and preservation measures and loss of some 

sites over time. 

No dedicated federal funds would be available 

to document and interpret cultural resources 

in a comprehensive manner outside of the 

ANF. 
 Executive Summary Environmental Assessment xxv

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Alternative C Alternative D

Alternative C would provide benefi cial effects on native 

plant protection and education along the San Gabriel 

River and in the highly visited upper watershed. This 

would occur through coordinated interpretive efforts, 

new resources for conservation, and new agency 

partnerships focused on conservation and restoration of 

native plant communities. 

Information centers located throughout the study area 

could also provide an opportunity for greater awareness 

with regard to native plant protection. 

As in alternative A, a component of native plant 

protection would be to focus on the control of nonnative 

species.

Alternative D would have the greatest benefi t for native 

plant habitat as it recognizes and promotes protection 

of habitat in the San Gabriel Mountains, Puente Hills, 

and along the San Gabriel River corridor. The NPS would 

provide technical assistance on a voluntary basis to 

conserve wildlife corridors and native habitats. 

The larger NRA would also provide coordinated interpretive 

efforts, new resources for conservation, and new agency 

partnerships focused on conservation of native plant 

communities. 

In Alternative C, the proposed designation would bring 

more resources to both the ANF and the San Gabriel River 

corridor for wildlife protection. Additionally, partnering 

entities would work to leverage greater funding for 

conservation along the San Gabriel River. 

Designation would ensure that proposed new or future 

uses on the national forest would be compatible with the 

protection of signifi cant resources and watershed values. 

This would have an overall benefi cial effect on protecting 

wildlife resources within the ANF.

The potential for increased water and land-based 

recreation opportunities could result in a minor adverse 

effect on wildlife and wildlife habitat. This would 

be mitigated through visitor education programs, 

monitoring, and restoration efforts.

Designation would ensure that proposed new or future 

uses on the national forest would be compatible with the 

protection of signifi cant resources and watershed values. 

This would have an overall benefi cial effect on protecting 

wildlife resources within the ANF.

Through partnerships, new funding, and technical 

assistance programs, alternative D would provide the 

greatest opportunity to protect habitat and connect wildlife 

corridors important for signifi cant resources. 

The potential for increased recreation opportunities, in 

areas where previous use has been light or nonexistent, 

could result in a minor adverse effect on wildlife and 

wildlife habitat. This would be mitigated through visitor 

education programs, monitoring, and restoration efforts.

In alternative C, NPS technical assistance for cultural 

resource protection would reinforce best management 

practices for protecting structures, landscapes, 

archeological resources, and ethnographic resources. 

Coordinated protection of cultural resources would be 

enhanced through NRA partnership agreements. 

Coordinated interpretation and education would have 

benefi cial effects on the protection and understanding of 

cultural resources. 

An increase in coordinated land conservation efforts 

would also likely enhance the protection of cultural 

and ethnographic resources on lands that are as yet 

undisturbed. 

Alternative D would be fundamentally the same as 

alternative C, but it would expand the protective 

boundaries and cover more sites and cultural themes since 

the area includes the entire San Gabriel Mountains portion 

of the ANF, the Puente Hills, and the San Gabriel River 

corridor. 

Alternative D would provide the most comprehensive and 

coordinated effort to protect cultural resources throughout 

the study area through:

• More NPS technical assistance

• More research and documentation of broader areas

• More comprehensive interpretation and education of 

broad cultural themes throughout the NRA.

• Expanded partnerships, coordination and consultation 

with stakeholder groups, including Native Americans.
xxvi Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Impact Topics No Action Alternative A

Recreation Use 

and Visitor and 

Experience

Higher demands would be placed on existing 

recreation areas with current trends in 

population growth. 

Inequities in recreation opportunities would 

likely continue. 

Recreational opportunities would occur 

only through existing agencies and local 

governments as funding permits. Lack of 

resources and personnel for recreation 

management would continue. 

Coordinated interpretation for signifi cant 

resources would not occur. 

Interpretation and educational programs 

in the ANF would continue to be greatly 

limited by current funding and staffi ng, 

having a moderate adverse impact on visitor 

experience. 

In alternative A, more USFS staff would be 

available within the new NRA to manage 

visitors. 

Additional funding for improved recreational 

facilities and more interpretive and educational 

programming would have a benefi cial effect 

on the visitor experience within the ANF. 

Alternative A would do little to ameliorate the 

lack of recreational opportunities available 

to urban areas that are currently defi cient in 

parks and open space. 

Socioeconomics Current trends in property values, economic 

activity, income, population, employment, 

recreation use and distribution, tourism, 

community relationships (as affected by local 

federal land use) would continue. 

Areas identifi ed as experiencing recreational 

high use would continue to be congested 

and noisy, with negative impacts on visitor 

experience and infrastructure.

The NRA designation and improved 

recreational opportunities would cause small 

increases in visitation over time. 

Increased visitation would have modest 

benefi cial effects on surrounding local 

communities which would provide services to 

such visitors.

Increased investment in the ANF to provide 

more staffi ng for visitor services, planning, and 

restoration could result in additional jobs for 

the region.

Socioeconomics 

-Socially and 

Economically 

Disadvantaged 

Populations

The existing lack of open space, lack of 

effective transportation, lack of culturally 

advantageous facilities or opportunities, and 

lack of knowledge about recreation and 

natural resources would continue to have 

moderate adverse impact on socially and 

economically disadvantaged populations.

Alternative A would have a generally 

benefi cial impact on socially and economically 

disadvantaged populations. However, it would 

likely represent only a minor improvement for 

communities that are currently underserved 

for opportunities to access natural resources 

and open space.
 Executive Summary Environmental Assessment xxvii

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Alternative C Alternative D

There would be more targeted planning efforts and 

leveraged funds to create recreational opportunities along 

the San Gabriel River. More trail connections and new 

transit options designed to connect communities to the 

NRA would improve access to recreational areas and open 

space. 

Through cooperative agreements, agencies would 

share staff to assist in visitor management. The NPS 

would also be able to provide staff assistance and visitor 

management technical assistance throughout the NRA. 

The voluntary information network would provide more 

opportunities to provide interpretive and educational 

programs about the resources of the San Gabriel River 

Watershed. 

Alternative C could also provide public health benefi ts to 

those communities near the San Gabriel River corridor.

Alternative D would have the greatest benefi cial effect on 

recreational opportunities and visitor experience. More trail 

connections and new transit options would improve access 

to recreational areas and open space. 

The NPS would provide technical assistance to improve 

open space and recreation planning in surrounding 

communities. 

Through cooperative agreements, agencies would share 

staff to assist in visitor management. The NPS would also 

be able to provide staff assistance for visitor management 

throughout the NRA. 

The larger NRA and voluntary information network 

would allow for coordinated interpretive and educational 

opportunities throughout the study area providing the 

greatest benefi cial effects on the visitor experience. 

Alternative D would have a greater benefi cial effect on 

public health for communities throughout the region, 

through providing the most new opportunities for outdoor 

recreation.

Small increases in visitation to NRA destinations could 

have modest benefi cial effects on surrounding local 

communities which would provide services to such 

visitors. 

The new designation would result in additional jobs to 

support the NRA. Job training would be incorporated into 

staffi ng and volunteer programs. Such effects would be 

negligible in the regional context.

Small increases in visitation over time could have 

modest benefi cial economic effects on surrounding local 

communities which would provide services to such visitors. 

With a larger designation, and a greater emphasis on 

education and job training, alternative D may provide 

slightly more benefi ts than the other alternatives in terms 

of creating jobs. Such effects would be negligible in the 

regional context.

Alternative C would have a greater benefi cial impact on 

socially and economically disadvantaged populations, 

with efforts applied specifi cally in urban areas close to the 

San Gabriel River. 

Alternative C provides job training and opportunities 

within these communities which has the potential both to 

improve access for recreation, but also to build programs 

to provide training and job opportunities. 

The development of effective and diverse partnerships 

would also serve to build programs and cooperative 

agreements with organizations that represent 

disadvantaged populations. 

With regional technical assistance programs, job training, 

and improved transportation connections to recreation 

and open space, alternative D presents the most resources 

and assistance for providing such communities with better 

access to recreational opportunities. 

As in C, alternative D provides job training and career 

opportunities for local communities.

As in alternative C, the development of effective and 

diverse partnerships would also serve to build programs 

and cooperative agreements with organizations that 

represent disadvantaged populations.
xxviii Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Impact Topics No Action Alternative A

Land Use Existing efforts to protect and conserve 

lands would continue at current levels. 

Regional growth and development, and lack 

of regional or coordinated planning efforts 

would continue to challenge local agencies 

and organizations in their efforts conserve 

open space.

Traffi c and congestion would continue to be 

affected primarily by regional growth and 

development. However, localized congestion 

at heavily used recreation sites would 

continue to have moderate adverse impacts 

on traffi c patterns in these areas.

Improved recreation opportunities and land 

conservation within the ANF would have an 

overall benefi cial effect on urban life and the built 

environment for surrounding communities.

Alternative A would have very little effect on traffi c 

patterns throughout the study area. However, with 

increases in visitation, alternative A could add a 

negligible adverse impact to local traffi c patterns 

associated with popular recreation areas.

Alternative A actions would apply only to national 

forest lands. There would be no impact on land 

use managed by existing agencies and local 

jurisdictions.

Water 

Resources

Water quality would vary greatly from 

location to location throughout the study 

area, depending primarily on the level of 

development and land uses. 

Limited funding for restoration, planning, 

and public education to address water 

quality impacts would result in continuing 

minor to moderate adverse impacts on 

water resources. 

The water quality of rivers and creeks in 

certain areas would continue to be a public 

health and safety concern. 

Additional emphasis on restoration and the 

protection of watershed resources would have a 

benefi cial effect on water resources in the ANF. 

Additional resources for visitor education and more 

rangers on-site in heavily used recreation areas 

could reduce pollution caused by recreational use 

thus having a benefi cial effect on water resources 

in the ANF. 

Improved water quality would have an indirect 

benefi cial effect on public health and safety.
 Executive Summary Environmental Assessment xxix

SUMMARY OF ENVIRONMENTAL CONSEQUENCES BY IMPACT TOPICS

Alternative C Alternative D

Alternative C would have a benefi cial impact on the 

availability of open space along the San Gabriel River 

corridor, having a benefi cial effect on urban quality and 

the built environment in these areas. 

When placed in the context of current transportation 

patterns, which are primarily affected by regional land 

use, growth and development, alternative C would 

have very little effect. Transportation improvements 

to destinations within the NRA, if implemented, could 

alleviate traffi c congestion in high use recreation areas. 

Such effects would be negligible in the regional context.

NPS management policies would apply only to NPSowned lands. There would be no impact on land use 

managed by existing agencies and local jurisdictions.

By emphasizing and protecting interconnected ecosystems 

within and among urban zones, providing more 

recreational opportunities, and protecting open spaces, 

alternative D would have the greatest benefi cial effect 

on open space availability, urban quality, and the built 

environment. 

With a broader emphasis on connecting people to 

recreation, providing more close-to-home recreation 

opportunities for urban communities, and improving 

transportation to major recreational destinations, 

alternative D could have benefi cial effects on reducing 

traffi c congestion in high use recreation areas. Such effects 

would be negligible in the regional context.

NPS management policies would apply only to NPS-owned 

lands. There would be no impact on land use managed by 

existing agencies and local jurisdictions.

Over time, restoration opportunities funded by the NRA 

partnership would have a benefi cial effect on San Gabriel 

River water quality. 

Alternative C would provide additional resources for 

visitor education, and more rangers on-site in heavily 

used recreation areas along the main corridors of the San 

Gabriel River. Additional resources for visitor education 

and more rangers on-site in heavily used recreation areas 

could reduce pollution caused by recreational use thus 

having a benefi cial effect on water resources where 

current impairments are a result of recreational use. 

The increased emphasis on river-based recreation, and 

potentially on other recreation uses throughout the 

expanded NRA, holds the potential for additional impacts 

on water resources. However, this would be mitigated 

through more visitor education programs and more 

on-site staff to manage visitation.

Improved water quality would have an indirect benefi cial 

effect on public health and safety.

Alternative D would provide more restoration opportunities 

throughout the San Gabriel Mountains, along the San 

Gabriel River, and Puente Hills. Over time, these efforts 

would have greater benefi cial effects on water resources 

than in alternative C. 

Alternative D would have similar benefi cial effects to 

alternative C for water quality on rivers and creeks that are 

primarily impacted by recreational use. 

Additionally, the NRA would provide regional technical 

assistance for improved recreational planning and 

restoration opportunities, providing the opportunity to 

focus on broader watershed restoration efforts.

The increased emphasis on river-based recreation, and 

new recreational opportunities throughout the expanded 

NRA, holds the potential for additional impacts on water 

resources. However, this would be mitigated through 

more visitor education programs and more on-site staff to 

manage visitation.

Improved water quality would have an indirect benefi cial 

effect on public health and safety.
xxx Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Next Steps

After the distribution of the Draft San Gabriel 

Watershed and Mountains Special Resource 

Study there will be a minimum 90-day review 

period. The NPS study team will then revise the 

report if needed, and transmit it to the Secretary 

of the Interior. The Secretary will transmit the 

report to Congress, along with the Secretary’s 

recommendation for the area.

The San Gabriel Mountains with the Los Angeles urban area in the foreground. Photo © David Liu.