4

121Suitability

Photos (clockwise): 1. Mt. Lowe Circlebridge View. NPS Photo. 2. Cooper’s Hawk. Photo by Eric Lowenbach. 3. Puente Hills. 

NPS Photo. 4. Aerial of the Los Angeles urban area. Photo by Bruce Perry, Dept. of Geological Sciences, CSU Long Beach.
122 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 
 Chapter 4: Suitability Introduction 123

Chapter 4: Suitability

Introduction

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. 

Adequacy of representation is determined on a 

case-by-case basis by comparing the potential 

addition to other comparably managed areas 

representing the same resource type, while 

considering differences or similarities in the 

character, quality, quantity, or combination of 

resource values. The comparative analysis also 

addresses rarity of the resources, interpretive and 

educational potential, and similar resources already 

protected in the national park system or in other 

public or private ownership. The comparison results 

in a determination of whether the proposed new 

area would expand, enhance, or duplicate resource 

protection or visitor use opportunities found in 

other comparably managed areas. The suitability 

analysis is applied to those areas found to be 

nationally signifi cant, the San Gabriel Mountains 

and the Puente-Chino Hills.

NPS Thematic Framework – 

Natural and Cultural Themes

The National Park Service (NPS) developed a 

thematic framework for evaluating potential and 

existing units within the national park system. 

The basic thematic framework includes a series of 

natural and cultural themes. 

Every unit of the national park system preserves 

important aspects of our nation’s natural and/or 

cultural heritage. The NPS uses a series of natural 

history and cultural themes to categorize the 

important resources protected by national park 

units. The themes are used to evaluate whether 

resources in a study area would broaden and 

diversify resources protected by the national park 

system. 

The following analysis is organized by natural 

history and cultural history themes represented by 

the study area. 

Natural History Themes

Biophysiographic Regions

The physiographic and biologic features of the 

country tend to be regionally oriented dividing the 

country into natural regions. These regions give 

primary consideration to the geologic histories, 

structures, and landforms, which in turn infl uence 

the climates, soils, vegetation, and animal life 

associated with the regions (NPS 1990). These 

biophysiographic regions provide the context for 

determining whether nationally signifi cant natural 

resources of an NPS special resource study area are 

adequately represented in the national park system 

or other comparably managed areas. The thematic 

framework is described in the publication “Natural 

History in the National Park System” (NPS 1990). 

The majority of the study area is located in the 

South Pacifi c Border biophysiographic province or 

natural region as described in “Natural History in 

the National Park System (see graphic, National 

Park biophysiographic regions).” The South Pacifi c 

Border region includes the southern Coast Ranges, 

the Transverse Ranges, the Peninsular Ranges of 

California and the Central Valley. These ranges have 

extensive forested areas composed of a mixture of 

coastal, Sierran, and inland species (NPS 1990). 

The northern end of the study area lies partially 

in the Mojave-Sonoran Desert region. This region 

includes the Mojave and Sonoran deserts in 

southeastern California, southernmost Nevada, 

and southern Arizona. Their physiographic features 

are roughly similar to those of the Great Basin. 

The major river system is the lower Colorado River. 

Both the Mojave and Sonoran deserts have hot 

summers and warm winters but their vegetation 

is different. The Mojave Desert of southern 

Nevada and southeastern California has simple 

plant communities dominated by creosote bush 

and bur-sage, with Joshua trees at 3000-4000 

feet. The Sonoran Desert, in Baja California and 

inland Mexico and extending in southern Arizona, 

has more diverse vegetation characterized by 

columnar cacti (NPS 1990). The study area does not 

contain any Sonoran Desert resources, therefore, 

this comparative analysis includes park units and 

comparable sites from the Mojave Desert portion 

of this region only (park units west of the Colorado 

River). 
124 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

National Park Biophysiographic Regions, adapted from the Physiographic Provinces Mpa, NNL Program, Pacifi c West 

Region, Oakland, CA 1/24/04, M.G. 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 125

Comparison of Similar Areas by 

Theme and Sub-Theme 

San Gabriel Mountains

NATURAL HISTORY THEMES REPRESENTED IN 

THE SAN GABRIEL MOUNTAINS

As described in Chapter 3, Resource Signifi cance, 

natural history themes are a series of categories 

encompassing the natural phenomena of the 

country. Themes represented by nationally 

signifi cant resources in the San Gabriel Mountains 

include:

• Landforms of the Present

• Land Ecosystems

• Aquatic Ecosystems

Landforms of the Present 

The “Landforms of the Present” theme describes 

the character of the landscape as a physical and 

scenic entity as it exists today, as well as present 

and past geologic events and processes. Principal 

features of the natural landscape such as mountain 

systems, river systems and lakes are included 

in this theme. Each landform possesses certain 

distinguishing qualities and characteristics which 

set it apart from others. The following sub-themes 

related to Landforms of the Present are represented 

in the San Gabriel Mountains:

• Mountain Systems: San Gabriel Mountains

• Sculpture of the Land: Devil’s Punchbowl

• River Systems and Lakes: East, West and 

North Forks of the San Gabriel River, Little Rock 

Creek, Santa Clara River

MOUNTAIN SYSTEMS

The form, composition, and structure of mountain 

systems are manifestations of a wide variety of 

geologic events and processes and constitute 

veritable record books of the earth’s history. 

As stated in Chapter 3, San Gabriel Mountains 

signifi cance lies in the evidence of active mountain 

building and the diverse array of geological 

features, both of which are directly associated with 

the San Andreas Transform Fault System. 

National Park Service Units

Existing national park units within the South Pacifi c 

Border and Mojave-Sonoran Desert Regions that 

represent the theme Mountain Systems include:

South Pacifi c Border Region

• Channel Islands National Park

• Golden Gate National Recreation Area

• Pinnacles National Monument

• Santa Monica Mountains National Recreation 

Area

• Whiskeytown-Shasta-Trinity National Recreation 

Area

Mojave-Sonoran Desert Region

• Death Valley National Park

• Joshua Tree National Park

• Lake Mead National Recreation Area

• Mojave National Preserve

Scientifi c Study and the San Andreas Fault

The San Andreas Fault System formed along the 

translational boundary between the North American 

and Pacifi c Plates. As one of the few places on Earth 

where a transform-fault plate-boundary occurs on 

land rather than beneath the sea, the San Andreas 

fault system is one of the most studied structural 

features on the planet. The theory of plate tectonics 

evolved based on scientifi c study of the San 

Andreas Fault. The San Gabriel Mountains were 

formed by the San Andreas fault to the north and a 

series of thrust faults to the south.

National park units within the two provinces 

that represent mountain systems which are also 

associated with the San Andreas fault system 

include Channel Islands National Park (NP), Golden 

Gate National Recreation Area (NRA), Pinnacles 

National Monument (NM), Santa Monica NRA, and 

Joshua Tree NP. 

Death Valley NP, Lake Mead NRA, Joshua Tree NP, 

and Mojave NP (including Cinder Cone National 

Natural Landmark) are more associated with active 

continental rifting processes associated with the 

Basin and Range Province. This area is characterized 

by fault-block mountain systems separated by 

basins or rift valleys. The Whiskeytown-ShastaTrinity NRA is located within mountain systems that 

are associated with subduction zones of the Pacifi c 

Northwest (Lillie 2005). 

Santa Monica NRA, Pinnacles NM, Golden Gate 

NRA, Channel Islands NP and Joshua Tree NP are 

national park units that have been changed and 

altered by activity along the massive San Andreas 

transform fault system. Of these national park units, 

Pinnacles NM is the only unit whose park purpose 

and signifi cance expressly relate to plate tectonics 

and the San Andreas fault. Pinnacles NM contains a 

remnant of an ancient strata volcano that was split 
126 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

by the movement of the two continental plates and 

provided key evidence for the basis of the theory 

of plate tectonics. The Pinnacles Rocks are believed 

to be part of the Neenach Volcano that occurred 

23 million years ago near present-day Lancaster, 

California, some 195 miles (314 km) southeast 

of Pinnacles. Activity on the San Andreas fault 

split the volcano and the Pacifi c Plate crept north, 

carrying the Pinnacles. 

The long history of research on the San Andreas 

fault in the San Gabriel Mountains, which continues 

today, expands on the story of plate tectonics told 

at Pinnacles NM. In the early 20th century, noted 

geologist Levi Noble conducted a long-term study 

of a fi fty-mile stretch of the San Andreas fault near 

the San Gabriel Mountains. Noble was the fi rst 

scientist to advance ideas about large-scale lateral 

movement on the San Andreas fault (Norris and 

Webb 1990, Wright and Troxel 2002). 

Noble’s 1927 landmark paper contains the fi rst 

printed statement that lateral displacement 

occurred along the San Andreas fault for many 

miles. Noble observes, “Scarcely anywhere in the 

fault zone are the rocks on the opposite sides of the 

master fault similar (Wright and Troxel 2002).” The 

concept was an important precursor to later ideas 

regarding plate tectonics (Carter 1982b). Since the 

time of Levi Noble, geologists and scientists have 

continued to make new discoveries and expand 

research on the San Andreas fault. 

The portion of the San Andreas fault that traverses 

the study area is also the location of the highest 

elevation point along the San Andreas Fault. This 

highpoint is located in the northeastern corner 

of the study area near the Big Pines area of the 

Angeles National Forest. Here one can see the 

deep and wide crevasse at the plate boundary. The 

deep crevasse highlights the magnitude of activity 

associated with this transform-plate boundary. 

Most areas along the San Andreas fault are fi lled 

with sediments, alluvium or water (in the case of 

sag ponds) which makes such landform gaps less 

obvious. The highpoint is therefore an excellent 

location to interpret this important geologic feature.

Active Mountain Building

 The San Gabriel Mountains may be one of the 

best locations in the United States to observe and 

study active mountain building. One of the most 

tectonically active mountain systems in the United 

States, tectonic activity along the San Andreas and 

other regional faults is forcing the mountains to 

rise at a rate of as much as 2 inches a year (Murphy 

1985). Large events such as the Sylmar earthquake 

of 1971 (6.6 magnitude) have resulted in the San 

Gabriel Mountains rising six feet in relation to the 

San Fernando Valley fl oor (Norris and Webb 1990). 

Geologic Diversity

The geologic composition of the San Gabriel 

Mountains also differs in rarity, quality and quantity 

from mountain systems at comparable national 

park units such as Pinnacles NM and Mojave NP. As 

described in the previous chapter, the San Gabriel 

Mountains contain the most extensive, bestexposed and most completely studied exposures 

of 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. While a rich array 

of ancient rocks are also found in Mojave NP, these 

geologic features differ from those represented 

in the San Gabriel Mountains. In addition, the 

relations of geologic formations present in the San 

Gabriel Mountains, but that are more widespread 

elsewhere in California, enable geologists to 

understand how the Earth’s crust has evolved in the 

region. In this way, the geologic composition of the 

San Gabriel Mountains serves as a “Rosetta Stone” 

for understanding the evolution of the Earth’s crust 

(Powell 2007a).

Of the national park units that represent the theme 

mountain systems, in no other single national park 

unit does the visitor have an opportunity to observe 

the forces of the San Andreas fault system and how 

it relates to active mountain building. The geologic 

diversity of the San Gabriel Mountains is also 

unique and has helped scientists to understand how 

the southern California region evolved.

Comparably Managed Areas

Outside of the national park system other areas that 

represent mountain systems include:

National Natural Landmarks (NNLs)

• Mt. Diablo State Park, CA

• Amboy Crater, CA

• San Andreas Fault, CA 

National Forests

• Angeles National Forest, CA

• San Bernardino National Forest, CA

National Natural Landmarks (NNLs) 

Mt. Diablo State Park, located in the northern South 

Pacifi c Border natural region, is not associated 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 127

with the San Andreas fault. Its primary signifi cance 

is that it contains the best examples of diapiric 

(igneous intrusion) geologic processes in the South 

Pacifi c Border natural region. 

The San Andreas Fault NNL consists of a privatelyowned winery located in San Benito County, CA. 

The Cienega Winery property represents one of 

the best illustrations of earth displacement caused 

by small crustal movements. One-half of a winery 

structure has moved eight inches in nine years. 

Although this site has been specifi cally designated 

to represent the San Andreas Fault, it does not have 

the long history of research associated with the 

San Gabriel Mountains, nor does it tell the story 

of active mountain building associated with the 

San Andreas fault. Because it is privately owned 

and managed, the site does not expressly interpret 

evidence of displacement. However, several online 

geologic guides direct visitors and students to 

portions of the building affected by displacement 

along the fault.

The only NNL in the Mojave-Sonoran natural region 

associated with the theme mountain systems is the 

Amboy Crater. Located in eastern San Bernardino 

County, Amboy Crater is an example of a recent 

volcanic cinder cone with an unusually fl at crater 

fl oor (NPS 2008a). Amboy Crater NNL is partially 

owned by the Bureau of Land Management (BLM). 

Other portions are located on private land. The 

BLM provides a viewing platform, interpretative 

information and trail access to the crater. 

National Forests. The San Gabriel Mountains 

are primarily managed by the Angeles National 

Forest. However, a comprehensive interpretive 

and educational program on the theme mountain 

building is currently lacking.

The San Bernardino Mountains in the San 

Bernardino National Forest are located just east 

of the San Gabriel Mountains and the Angeles 

National Forest. The two ranges are separated 

by the Cajon Pass which was formed by the San 

Andreas fault. The San Andreas fault lies to the 

south of the San Bernardino Mountains, whereas it 

lies north of the San Gabriel Mountains. Although 

the San Bernardino Mountains are directly affected 

by the forces of the San Andreas fault, they do 

not experience the rapid uplift associated with the 

San Gabriel Mountains which are compressed by 

the San Andreas fault to the north and a series of 

thrust faults to the south. Thus, the topography 

of the San Bernardino Mountains is much gentler. 

While similar geologic units are found in the San 

Bernardino Mountains, the geologic make-up of 

the San Gabriel Mountains differs vastly from the 

San Bernardino Mountains. Ancient rocks in the 

San Gabriel Mountains are not found in the San 

Bernardino Mountains. 

Compared to the San Bernardino Mountains, the 

San Gabriel Mountains have greater opportunity 

for interpretation, education and scientifi c study of 

the San Andreas fault, plate tectonics, mountain 

building and regional geology.

Conclusion: Mountain Systems

Of the national park units and comparably 

managed areas that represent the theme mountain 

systems, in no other area does the visitor have 

an opportunity to observe the forces of the San 

Andreas fault system and how it relates to active 

mountain building. In addition, the San Gabriel 

Mountains contain a diversity of geological features 

that represent some of the oldest rocks on the 

west coast of California. These units have helped 

geologists to understand how the Earth’s crust has 

evolved in the region. The San Gabriel Mountains 

could expand greatly on the story of the San 

Andreas fault and plate tectonics in the national 

park system.

SCULPTURE OF THE LAND

The Sculpture of the Land sub-theme includes 

landforms produced by erosive action of water and 

wind, landslides and other physical or chemical 

land shaping events or phenomena. The Devil’s 

Punchbowl is an excellent example of sculpture of 

the land created by impressive geologic forces. 

The scenic Devil’s Punchbowl consists of 

magnifi cently exposed ridges and ravines etched 

into steeply tilted and folded sandstone that 

protrudes out of the surrounding substrate. Located 

between the San Andreas and Punchbowl fault 

zones, tectonic activity forced the Devil’s Punchbowl 

formation into areas of older crystalline rocks 

associated with the San Gabriel Mountains. This 

striking landform is a dramatic example of earth 

movement caused by plate tectonics.

The Devil’s Punchbowl was identifi ed by two 

previous studies as a nationally signifi cant

geological feature (NPS 1974 and NPS 1976). The 

latter study recommended it for designation as 

a National Natural Landmark. It was described 

as “an ideal place to ponder the importance of 

the regional faults and to view the San Gabriel 

Mountains (NPS 1976).” Managed by Los Angeles 

County Parks, the Devil’s Punchbowl features an 

interpretive center and interpretive trails which 

explain the signifi cance of the site.
128 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

National Park Service Units

There are numerous national park units within the 

South Pacifi c Border and Mojave-Sonoran Desert 

natural regions that represent the theme Sculpture 

of the Land including:

South Pacifi c Border Region

• Channel Islands National Park

• Golden Gate National Recreation Area

• Pinnacles National Monument

• Santa Monica Mountains National Recreation 

Area

Mojave-Sonoran Desert Region

• Death Valley National Park

• Joshua Tree National Park

• Lake Mead National Recreation Area

• Mojave National Preserve

Of the NPS units in the South Pacifi c Border and 

Mojave-Sonoran natural regions, landforms within 

Pinnacles NM, Joshua Tree NP, Death Valley NP, 

Mojave NP and Lake Mead NRA are most similar to 

the Devil’s Punchbowl in the San Gabriel Mountains. 

Pinnacles National Monument features volcanic 

breccia that was associated with an ancient 

volcano. Over time these formations have been 

impacted by wind, erosion and seismic activity 

associated with the San Andreas fault which has 

caused cracks and talus cave features. While these 

features provide an ideal location to learn about 

and study the San Andreas fault and plate tectonics, 

they differ from the Devil’s Punchbowl which was 

down-dropped into areas of older crystalline rocks 

creating stark contrasts between the structure and 

its surrounding landscape. 

Joshua Tree NP features giant granite boulders 

that are related to the effects of subduction along 

the San Andreas fault. These granite boulders are 

remnant magma chambers that formed during 

subduction of the Farallon Plate (Lillie 2005). 

Although related to activity along the San Andreas 

fault, these features are located quite a distance 

from the fault itself. 

Death Valley NRA, Mojave NP and Lake Mead 

NRA are renowned for their unusual geologic 

features associated with the Mojave Desert, 

Colorado Plateau and the Basin and Range geologic 

provinces. Some of these forms bear resemblance 

to the Devil’s Punchbowl in the San Gabriel 

Mountains. For example, Marble Mountain in Death 

Valley NP features dipping sedimentary rocks and 

Lake Mead NRA contains a steeply dipping cliff face 

at Gale Hills. Mojave NP is signifi cant for volcanic 

geological features such as Cima Dome, the Cinder 

Cones, as well as the Kelso Dunes. However, none 

of these features are directly associated with the 

San Andreas fault. 

Channel Islands NP, Golden Gate National NRA, and 

Santa Monica Mountains NRA contain examples of 

sculpture of the land related to both plate tectonics 

as well as the ongoing erosion associated with 

coastal environments. 

Comparably Managed Areas

Outside of the national park system other areas that 

represent the sculpture of the land include:

National Natural Landmarks (NNLs)

• Anza-Borrego Desert State Park, CA

• Rainbow Basin, CA

• Turtle Mountain Natural Area, CA

• Ramsey Canyon, AZ

County Parks

• Devil’s Punchbowl Natural Area, CA

• Vasquez Rocks County Park, CA

National Natural Landmarks (NNLs)

Anza-Borrego Desert State Park NNL, most of 

which is located in eastern San Diego County, is the 

largest desert state park in the nation. The state 

park contains some of the best examples of the 

various desert biotic communities in the Colorado 

Desert as well as excellent examples of desert 

geological phenomena. A combination of upthrusting and subsidence formed this park’s unique 

landforms which consist of valleys, badlands, 

canyons, oases, and mountain ranges.

Rainbow Basin NNL is located in San Bernardino 

County eight miles north of Barstow. Managed 

by the Bureau of Land Management, the basin is 

notable for the fantastic and beautiful shapes of its 

rock formations, particularly the Barstow Syncline. 

However, the primary signifi cance of this site is the 

fossil evidence of insects, larger Micoene mammals 

and mammal tracks and the deep erosional canyons 

with rugged rims. 

Also located in San Bernardino County, the 

Turtle Mountain Natural Area NNL, managed by 

the Bureau of Land Management, features two 

mountain sections entirely different in composition 

which illustrate past volcanic phenomena with 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 129

superimposed sculpturing of mountain landforms 

by weathering and uplift. 

Ramsey Canyon Preserve’s primary signifi cance 

is its well-defi ned habitat created by a verticalsided gorge. The gorge features an extension of 

Mexican fl ora and fauna into the American side 

of the International Boundary, and contains plants 

which normally occur only at higher elevations. 

The preserve is owned and managed by the Nature 

Conservancy (NPS 2008a).

The landforms in these NNLs differ from Devils 

Punchbowl Formation. While the San Gabriel 

Mountains are directly infl uenced by forces on the 

San Andreas fault, most of the NNLs that represent 

“sculpture of the land” are primarily desert 

landscapes more closely associated with forces of 

the Basin and Range geologic province. 

County Parks. A good portion of the Devil’s 

Punchbowl formation in the San Gabriel Mountains 

is currently managed by Los Angeles County Parks. 

The Devil’s Punchbowl Natural Area features a small 

nature center with information about the area’s 

geology, wildlife, plants. Guided tours are offered 

about such topics and various hiking trails area 

available for visitors to experience the resources. 

Wedged between the San Gabriel Mountains and 

the Sierra Pelona Mountains in the Soledad Basin, 

the Vasquez Rocks are composed of steeply tilted 

andesite volcanic rocks, non-marine red beds, 

sedimentary breccia, claystone, mudstone and 

limestone. The Vasquez formation is spectacularly 

displayed at Vasquez Rocks County Park just west 

of the study area where the rocks were thrust up as 

the North American tectonic plate initially collided 

with the Pacifi c Plate about 25 million years ago. 

The Vasquez Formation volcanic rocks are also 

found in the San Gabriel Mountains along the 

Soledad Basin. 

The Vasquez Rocks are similar in character to the 

Devil’s Punchbowl. However, they do not feature 

the dramatic contrast in geologic units that is 

evident at the Devil’s Punchbowl. 

Conclusion: Sculpture of the Land 

While many national park units in South Pacifi c 

Border and Mojave-Sonoran natural regions contain 

striking landforms similar to the Devil’s Punchbowl, 

Devil’s Punchbowl’s prominent location in the San 

Andreas Fault zone makes it an ideal location to 

learn about the signifi cance of the this important 

fault while enjoying a highly scenic landscape. The 

Devil’s Punchbowl features are sharply contrasted 

with its surrounding geology and landscape creating 

one of the most dramatic examples of earth 

movement caused by plate tectonics and active 

mountain building. Interpretation and education on 

plate tectonics and geology is currently available at 

the Devil’s Punchbowl Natural Area.

Of the comparably managed areas that represent 

the theme sculpture of the land, the Vasquez Rocks 

County Park is most similar to the Devil’s Punchbowl 

in terms of its character and the opportunity to 

interpret plate tectonics and the San Andreas Fault. 

The NNLs that currently represent sculpture of the 

land are more associated with the Basin and Range 

geologic province. They do not present the same 

opportunity to interpret the San Andreas Fault, 

plate tectonics and active mountain building. 

RIVER SYSTEMS AND LAKES

River systems and lakes are noteworthy features 

of the natural landscapes often revealing past and 

ongoing geological process. Portions of the river 

systems in 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. The riparian areas in the 

San Gabriel Mountains provide some of the richest 

habitat for freshwater fi shes in southern California. 

National Park Service Units. Existing national 

park units within the South Pacifi c Border and 

Mojave-Sonoran Desert Regions that represent the 

theme River Systems and Lakes include:

South Pacifi c Border Region

• Channel Islands National Park

• Golden Gate National Recreation Area

• Santa Monica Mountains National Recreation 

Area

• Whiskeytown-Shasta-Trinity National Recreation 

Area

Mojave-Sonoran Desert Region

• Lake Mead National Recreation Area

Of these national park units, Channel Islands NP 

and Santa Monica Mountains NRA represent river 

systems most similar in quality and character to the 

systems found in the San Gabriel Mountains. While 

the Golden Gate and Whiskeytown-Shasta-Trinity 

NRAs contain excellent examples of river systems and 

lakes, these systems differ from those represented 

in the San Gabriel Mountains in that they are more 

associated with northern California ecosystems. 
130 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

The Santa Monica Mountains NRA is home to 

freshwater aquatic habitats and two of the last salt 

marshes on the Pacifi c Coast. While this habitat 

provides refuge to a signifi cant number of rare 

species, the primarily marine infl uence and lower 

elevations support different species than those 

found in the San Gabriel Mountains. The San 

Gabriel River and its mountain tributaries provide 

some of the richest habitat for native freshwater 

fi shes in southern California. Similarly, the tidal 

systems at Channel Islands NP are heavily marine 

infl uenced and differ in both vegetative structure 

and species composition from the San Gabriel 

Mountains. 

The character of river systems in the Santa 

Monica Mountains NRA and Channel Islands NP 

are different from the river systems in the steep, 

rugged San Gabriel Mountains. River systems in 

the San Gabriel Mountains are highly infl uenced 

by the topography and active geologic processes. 

Measured as a function of the horizontal distance 

from the ocean, these mountains present the 

greatest vertical elevation gain from the ocean 

when compared to anywhere else in the continental 

United States (McPhee 1989; Gumprecht 1999). 

The proximity of mountains to the sea presents 

unique climatic conditions and orographic effects, 

causing large amounts of annual rainfall and 

signifi cant fl ooding. Combined with the rapid 

erosion resulting from the active mountain-building 

in the San Gabriel Mountains, the river systems 

of the Los Angeles Basin are some of the most 

dynamic in California. Residents of the Los Angeles 

Basin went through extraordinary efforts in their 

attempts to stabilize these rivers. The result is the 

development of one of the most comprehensive 

fl ood control projects undertaken in the United 

States. The San Gabriel Mountains are an ideal 

location to interpret this story.

Signifi cant desert river systems can be found at 

Lake Mead NRA. Despite alteration of the riverine 

environment from dams, the lakes at Lake Mead 

NRA contain excellent examples of desert riparian 

systems and provide habitat to rare and endangered 

species. This includes two endemic fi sh species 

listed as federally endangered, the razorback sucker 

and the bonytail chub. These species are native to 

Mojave, Colorado Plateau and Basin and Range 

geologic provinces. 

Whereas Lake Mead features mostly lacustarine 

riparian areas, outstanding examples of desert 

riparian areas in the San Gabriel Mountains are 

associated with Little Rock Creek. Little Rock Creek 

is the only eligible Wild and Scenic River on the 

northern slope of the San Gabriel Mountains which 

drains into the Mojave Desert region. Little Rock 

Creek differs in character from the other three units 

in that it traverses a greater elevation change. Over 

its course, Little Rock Creek transitions quickly from 

Sierran mixed conifer habitat in its upper watershed 

to juniper woodlands and fi nally to desert scrub 

habitat as it spreads into the Mojave Desert to the 

north.

The desert and high country setting of Little Rock 

Creek attracts visitors for picnicking, water play and 

driving opportunities and features a diverse array 

of wildlife including threatened, endangered, and 

sensitive species. Also present are prehistoric sites 

valued by local Native American tribes (USFS 2005). 

The Little Rock Creek is an excellent location to 

interpret the ecological transition from the southern 

California coastally infl uenced Mediterranean 

ecosystem to the Mojave Desert ecosystem as well 

as prehistoric human occupation of these sites.

Comparably Managed Areas

Outside of the national park system other areas that 

represent the River Systems and Lakes include:

National Natural Landmarks (NNLs)

• San Felipe Creek Area, CA 

National Forests and Private Reserves

• Angeles National Forest, CA

• San Bernardino National Forest, CA

• Los Padres National Forest, CA

• Santa Margarita Ecological Reserve, CA 

National Natural Landmarks (NNLs)

No NNL was identifi ed for the South Pacifi c Border 

natural region that represents the theme River 

Systems and Lakes. Within the Mojave-Sonoran 

Desert natural region, the San Felipe Creek Area in 

San Diego County features a marsh area containing 

what is probably the last remaining perennial 

natural desert stream in the Colorado Desert. 

Managed by the California Department of Fish and 

Game, this ecological reserve is open to the public 

for hiking and viewing wildlife. The Colorado Desert 

ecosystem is distinctly different in character from 

desert ecosystem associated with the San Gabriel 

Mountains (NPS 2008a).

National Forests. The Angeles National Forest 

manages eligible wild and scenic rivers in the San 

Gabriel Mountains. However, some segments are 

currently impacted by heavy visitation. Expanded 

visitor education programs about the importance of 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 131

these water resources and proper stewardship could 

expand and enhance their protection, and improve 

the overall visitor experience. 

National Forests with comparable river systems 

to those found on the Angeles National Forest 

include rivers in the San Bernardino NF and the 

Los Padres NF. Located in the coastal mountains of 

the southern California coast, the San Bernardino 

and Los Padres National Forests both contain river 

segments that are eligible for Wild and Scenic River 

status. The Sisquoc River, Sespe Creek, and Big Sur 

River in the Los Padres National Forest are the only 

rivers within the South Pacifi c Border Region that 

are designated Wild and Scenic Rivers.

The U.S. Forest Service has identifi ed twelve rivers 

on the San Bernardino National Forest that are 

eligible for Wild and Scenic River status. These 

rivers would be most comparable to those found 

in the San Gabriel Mountains. Although many of 

these rivers have comparable scenic, wildlife and 

recreational value, eligible river segments in the San 

Gabriel Mountains differ in both physical character 

and quantity of native fi sheries. 

Historically, the San Gabriel River was the most 

abundant trout stream in Southern California 

(Robinson 1946). Today, the West, North, and East 

forks of the San Gabriel River and their tributaries 

still contain highly signifi cant aquatic habitats (Swift 

et al 1993, Deinstadt et al 1990). Rainbow trout 

populations occur on the West, North, and East 

Forks of the San Gabriel River, and in both San 

Gabriel and Cogswell Reservoirs. Average densities 

of over 3,500 fi sh per mile have been recorded 

on the West Fork (Deinstadt et al 1990). The San 

Gabriel River also contains the largest remaining 

populations of Arroyo chub (Wells et al 1975) and 

the Santa Ana speckled dace (Swift et al 1993). The 

San Gabriel River thus provides some of the best 

opportunities to interpret southern California native 

freshwater fi sheries.

The Los Padres National Forest has three Wild and 

Scenic Rivers – a segment of the Sespe Creek, the 

Sisquoc River, and the Bid Sur. A four-mile segment 

of Sespe Creek in the Los Padres NF was included 

in the Wild and Scenic River system in 1992. Sespe 

Creek represents fi ve outstandingly remarkable wild 

and scenic river values including: recreation, wildlife, 

geologic, fi shery and scenic. Sespe Creek forms 

highly scenic, deep gorges that expose formations 

of the Topa Topa Mountain range. The creek is one 

of the southernmost anadromous fi shery habitats 

(southern steelhead) in California. Other federally 

listed species found within the creek include the 

arroyo toad and the California condor. 

Although access to Sespe Creek is limited since 

the Wild and Scenic river segment is primarily in 

wilderness areas, several trails provide opportunities 

for hiking, swimming and equestrian use along 

Sespe Creek (USFS 2003b). 

The Sisquoc Wild and Scenic River is located in the 

Los Padres NF, in the County of Santa Barbara. The 

outstandingly remarkable values for the Sisquoc 

River are scenic, recreation, wildlife, heritage, and 

ecological values. The extensive riparian corridor, 

along the Sisquoc River remains relatively natural 

and surrounded by a large wilderness area. The 

scenic value of the river is associated with the 

narrow corridor of the river itself and the contrast 

of the geologic features, water, and riparian 

vegetation. Several federally listed threatened 

or endangered species are found in a relatively 

undisturbed riparian habitat. These species include 

Central California Coast Steelhead trout, California 

red-legged frogs, Arroyo toads, Least Bell’s vireos, 

and California condors.

The Sisquoc River corridor has abundant prehistoric 

and historic sites. Patterns of travel and settlement 

along the river’s length, and the sites that stand in 

evidence of the past, refl ect the distinctive nature 

of the drainage. The corridor frequently has narrow 

travel passages, and many adjacent high fl ats 

that were occupied in prehistoric times and often 

homesteaded and cultivated in more recent times. 

The area also has cultural signifi cance to modern 

Native Americans (USFS 2003c).

The Sisquoc River corridor offers excellent 

opportunities for solitude, primitive camping, 

hiking, horseback riding and other wilderness 

oriented activities. There is an established trail 

system that generally parallels the river out of the 

fl oodplain that periodically crosses the river. 

The Big Sur Wild and Scenic River is located in the 

Los Padres NF. Outstanding remarkable values for 

which the Big Sur River was designated include 

scenic, recreation, and ecological values. Scenic 

values include: abundant, rapid, fl owing water, 

with pools, springs and an occasional waterfall; 

interesting landforms; diverse tree canopy with 

redwoods; combination of scenic features 

uncommon to Central and Southern California. 

The three natural sulfur hot springs pools and the 

redwood-riparian environment provide outstanding 

opportunities for hiking, camping, swimming, 

fi shing, picnicking, and nature study. Outstanding 

ecological values include a diverse combination of 

alders, maples, willows and bay with dominant over 

story of redwood (USFS 2003d).
132 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Although the three Los Padres NF Wild and Scenic 

Rivers are outstanding examples of river systems, 

these systems differ signifi cantly in character from 

rivers systems in the San Gabriel Mountains. The 

Sespe, Sisquoc and Big Sur Wild and Scenic Rivers 

support different fi sheries, vegetation types and 

have distinctly different geologic make-ups than 

that of the San Gabriel River. 

Private Reserves. The Santa Margarita River, 

located south of the study area in San Diego 

County, is the longest protected coastal river in 

southern California. Upper portions of the river 

are located in unincorporated areas of San Diego 

County while lower portions are protected by 

the Santa Margarita Ecological Reserve and the 

Department of Defense at Camp Pendleton. In 

contrast to the San Gabriel River, Santa Margarita 

River has its most signifi cant resources in its lower 

reaches. These sections differ signifi cantly in 

vegetative structure and geologic make-up from the 

San Gabriel Mountains. Although the lower Santa 

Margarita River offers exception educational and 

research opportunities, the restricted access limits 

interpretive and recreational opportunities. 

Conclusion: River Systems and Lakes 

While several national park units in the South 

Pacifi c Border and Mojave-Sonoran natural 

regions contain excellent representations of the 

theme River Systems and Lakes, the San Gabriel 

Mountain river systems differ signifi cantly in 

geologic character and processes and diversity of 

river habitats. Access to signifi cant river systems in 

the San Gabriel Mountains is excellent. The rivers 

provide opportunities to interpret how the impact 

of mountain building on river processes shaped the 

Los Angeles Region.

Of the comparably managed areas, the San Gabriel 

Mountain river systems differ in geologic character 

and geologic processes, habitat type, fi sheries and 

opportunities for access and interpretation.

Land Ecosystems 

The theme “Land Ecosystems” represents 

vegetation types as well as the animal populations 

and physical environmental features which are often 

important elements in identifying and evaluating 

sites. The following sub-themes related to Land 

Ecosystems are represented in the San Gabriel 

Mountains:

• Chaparral (shrubs and evergreen forest trees): 

Coastal sage scrub, San Dimas Experimental 

Forest (chaparral)

• Dry Coniferous Forest: Bigcone Douglas-fi r, 

pinyon-juniper forest, subalpine forest.

CHAPARRAL

Chaparral ecosystems include broad-leafed, mainly 

evergreen, species of shrubs or low trees, occurring 

as dense scrub or woodland. Almost 50% of the 

study area land cover is chaparral habitat. 

The San Dimas Experimental Forest in the Angeles 

National Forest has been a leader in research of 

chaparral ecosystems and watersheds and provides 

superlative opportunities for scientifi c study. 

National Park Service Units

Existing national park units within the South Pacifi c 

Border and Mojave-Sonoran Desert Regions that 

represent Chaparral include:

South Pacifi c Border Region

• Cabrillo National Monument

• Channel Islands National Park

• Pinnacles National Monument

• Santa Monica Mountains National Recreation 

Area

• Whiskeytown-Shasta-Trinity National Recreation 

Area

Mojave-Sonoran Desert Region

• Joshua Tree National Park

Whiskeytown-Shasta-Trinity NRA represents 

chaparral species associated with more northern 

California affi nities and Pinnacles NM represents 

chaparral communities associated with central 

California. Similarly, chaparral communities 

represented in the Mojave-Sonoran Desert natural 

region are more representative of desert chaparral 

communities. The Santa Monica Mountains NRA 

contains chaparral habitat most similar chaparral in 

the San Gabriel Mountains. However, given that the 

San Gabriel Mountains are located in a transition 

zone between two ecoregions, and the range of 

chaparral types associated with different elevations 

and climate, the San Gabriel Mountains contain a 

greater diversity of chaparral habitat.. 

The presence of the San Dimas Experimental Forest 

in the San Gabriel Mountains is what distinguishes 

this area the most from existing units that represent 

the theme Chaparral. No other location has the 

extensive history of research and experimentation 

on chaparral watersheds. Data collected in the San 

Dimas Experimental Forest since 1933 represents 

some of the earliest and most comprehensive 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 133

records from continuously monitored U.S. Forest 

Service experimental watersheds in the United 

States. 

Of the three national park units in the South Pacifi c 

Border natural region, Santa Monica Mountains 

NRA mostly closely represents chaparral habitat 

similar to what is found in the San Gabriel 

Mountains.

In recent years, the National Park Service has 

established Research Learning Centers throughout 

the nation to facilitate research efforts and 

provide educational opportunities. The California 

Mediterranean Research Learning Center (CMRLC) 

is an integral program of three units of the national 

park system: Cabrillo National Monument, Channel 

Islands National Park, and Santa Monica Mountains 

National Recreation Area. These three NPS areas 

represent outstanding examples of Southern 

California’s Mediterranean Biome which includes 

chaparral communities. 

The California Mediterranean Research Learning 

Center was established to support a broad scope 

of research on the terrestrial and oceanic aspects of 

the Mediterranean Biome, and promote research 

directed specifi cally at addressing management 

needs. Through the CMRLC, the NPS plans to 

engage citizens in science and research and will 

place a strong focus on education. While the 

CMRLC will likely conduct important research on 

chaparral systems, the program is new and does not 

have the years of focused, controlled research that 

has been conducted at the San Dimas Experimental 

Forest. The CMRLC will provide educational 

opportunities for the public which is currently not a 

function of the San Dimas Experimental Forest.

Comparably Managed Areas

Outside the national park system other areas that 

represent chaparral include:

National Natural Landmarks (NNLs)

• American River Bluffs and Phoenix Park Vernal 

Pools , CA

• Año Nuevo Point and Island, CA

• Miramar Mounds, CA

• Nipomo Dunes-Point Sal Coastal Area, CA 

• Tijuana River Estuary , CA

National Forests

• Angeles National Forest, CA

• San Bernardino National Forest, CA

• Los Padres National Forest

• Cleveland National Forest, CA

National Natural Landmarks (NNLs)

The American River Bluffs and Phoenix Park Vernal 

Pools located outside of Sacramento, CA contain 

outstanding examples of rare plant community 

types such as blue oak woodlands and vernal pools. 

The landmark is owned by federal, county and 

private owners. Public access is readily available 

along the bluffs which feature a continuous trail. 

The Phoenix Park Vernal Pool Preserve is managed 

by the City of Fair Oaks Recreation and Park 

District. The pools are sensitive and public access is 

restricted.

Año Nuevo Point and Island on the northern 

California coast is the best known breeding ground 

in the world for the northern elephant seal; it is also 

habitat for Steller sea lions, California sea lions, and 

harbor seals. The area is managed by California 

State Parks. 

Miramar Mounds in San Diego, California is an 

example of vernal pools habitat and distinctive 

geomorphic forms and soils that are now rare 

within California, particularly in coastal southern 

California. The Miramar Mounds NNL is owned and 

managed by the Department of Defense as part of 

the Marine Corps Air Station Miramar. 

The Nipomo Dunes-Point Sal Coastal Area contains 

the largest, relatively undisturbed coastal dune tract 

in California, supporting both rare and endangered 

plants and animals and great species diversity and 

one of the last remaining tracts of pristine rocky 

coastline in the South Coast Ranges. The landmark 

is managed owned by federal, state, county and 

private landowners. 

The Tijuana River Estuary on the southernmost tip 

of California is of the fi nest remaining saltwater 

marshes on the California coastline, containing 

three species of endangered birds and an important 

habitat for other wildlife, especially waterfowl (NPS 

2008a). 

While each of these NNL sites contain chaparral 

habitat, the quality of the chaparral is not the 

primary signifi cance or purpose for designating any 

of the NNLs. None of the NNL sites has a chaparral 

research component similar to the San Dimas 

Experimental Forest.

National Forests. Southern California’s four 

national forests (Angeles, Los Padres, Cleveland 

and San Bernardino) manage most of the southern 

California’s chaparral resources. While national 

forest status ensures that the chaparral habitat 
134 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

is under some level of federal protection, threats 

to chaparral in the national forests include 

infrastructure development such as power lines and 

roads, and increasing fi re frequency as a result of 

human-caused ignitions (Halsey 2005). 

The Angeles National Forest is home to the San 

Dimas Experimental Forest, unique among the 

four national forests, where signifi cant research 

about chaparral ecosystems and watersheds has 

contributed to our knowledge and management of 

this type of ecosystem. Currently, there is little to no 

opportunity to provide interpretive and educational 

opportunities about the San Dimas Experimental 

Forest and the signifi cant resource contributions 

which it has generated, both nationally and 

internationally. A comparison to other experimental 

forests and stations is further analyzed later in the 

cultural themes section of this chapter.

Conclusion: Chaparral

Of the national park units and comparably 

managed areas that contain signifi cant chaparral 

ecosystems in the South Pacifi c Border natural 

region, no other site has been so signifi cant for 

historical and contemporary research on chaparral 

ecosystems and watersheds as the San Dimas 

Experimental Forest located within the San Gabriel 

Mountains. Additionally, the chaparral habitat types 

in the San Gabriel Mountains are diverse covering 

a range of elevations and spanning two distinct 

ecoregions.

DRY CONIFEROUS FOREST

This sub-theme includes belts of coniferous forest 

and woodland dominated by Douglas-fi r, ponderosa 

pine, and pinyon-juniper. At its lower limits these 

forests give way to steppe or chaparral ecosystems.

Outstanding examples of dry coniferous forest 

communities in the San Gabriel Mountains and 

foothills include: bigcone Douglas-fi r, relict juniper 

communities, and southern California subalpine 

habitat. 

National Park Service Units

Existing national park units within the South Pacifi c 

Border and Mojave-Sonoran Desert Regions that 

represent the theme Dry Coniferous Forest include:

South Pacifi c Border Region

• Channel Islands National Park

• Golden Gate National Recreation Area

• Pinnacles National Monument

• Santa Monica Mountains National Recreation 

Area

• Whiskeytown-Shasta-Trinity National Recreation 

Area

Mojave-Sonoran Desert Region

• Death Valley National Park

• Mojave National Preserve

• Saguaro National Monument

• Montezuma Castle National Monument

Because of its high elevation, the San Gabriel 

Mountains contain rare examples of southern 

California subalpine vegetation. No other national 

park unit in the South Pacifi c Border natural region 

or the Mojave-Sonoran Desert Region contains this 

type of habitat which includes an unusual subalpine 

forest of krummholz lodgepole pine (Pinus 

murrayana) and 1,000 year-old limber pines. 

Although examples of bigcone Douglas –fi r and 

juniper woodlands are found in many of the existing 

national park units, the San Gabriel Mountains 

contain unique and outstanding examples of this 

type of habitat. The relict juniper woodland found 

at Mescal Creek in the San Gabriel Mountains is a 

remnant of vegetation that was prevalent in this 

area during the Pleistocene epoch (1.8 million - 

8,000 years ago.) The bigcone Douglas-fi r habitat 

found at Falls Canyon Research Natural Area is one 

of the best remaining examples of this declining 

community. Stands here include dense, mature 

bigcone Douglas-fi r trees, some of which are over 

350 years old. 

Comparably Managed Areas

Outside of the national park system other areas that 

represent Dry coniferous forest include:

National Natural Landmarks (NNLs)

• Consumnes River Riparian Woodlands, CA

• Patagonia-Sonoita Creek Sanctuary, AZ

• Ramsey Canyon, AZ 

National Forests and Monuments

• Angeles National Forest, CA

• San Bernardino National Forest, CA

• Santa Rosa and San Jacinto Mountains National 

Monument, CA

National Natural Landmarks (NNLs)

The three National Natural Landmarks contain 

plant communities associated with dry coniferous 

forest. Consumnes River Riparian Woodlands 

contain a small remnant of a rapidly disappearing 

riparian woodland community type that once 
 Chapter 4: Suitability Comparison Of Similar Areas By Theme And Sub-theme 135

formed a major part of the California Central 

Valley. The Patagonia-Sonoita Creek Sanctuary 

in Arizona features permanent stream-bottom 

habitat supporting rare aquatic biota, including 

the Gila Topminnow. This site is also the only 

known nesting spot in the country for the rare 

rose throated becard. Ramsey Canyon in Arizona 

features a vertical-sided gorge containing a welldefi ned microclimatic habitat, which consists of 

an extension of Mexican fl ora and fauna into 

the American side of the International Boundary, 

and contains plants which normally occur only at 

higher elevations (NPS 2008a).All three of these 

landmarks are managed by the Nature Conservancy. 

Each site contains a visitor/nature center and some 

opportunities for passive recreation such as wildlife 

viewing, nature study and hiking.

Although these three NNLs contain some dry 

coniferous forest habitat, this type of habitat is not 

dominant in any of the units. Each was established 

for their outstanding representation of riparian 

vegetation. Additionally, the combination of plant 

communities within these three NNLs is quite 

different than the signifi cant habitats represented in 

the San Gabriel Mountains.

National Forests and Monuments. The San 

Bernardino National Forest contains examples of 

Dry Coniferous Forest habitat types most similar 

to the San Gabriel Mountains. The Millard Canyon 

Research Natural Area contains well-developed 

bigcone Douglas fi r. However, this area is primarily 

preserved for its representation of interior live oak 

vegetation.

The Santa Rosa and San Jacinto Mountains National 

Monument (monument) is located approximately 

100 miles east of Los Angeles encompassing 

89,500 acres, the monument is jointly managed by 

the Bureau of Land Management, the Forest Service 

(San Bernardino NF) lands, the Agua Caliente Band 

of Cahuilla Indians, California State Parks, and the 

California Department of Fish and Game.

Within the monument vegetation ranges from 

cactus, creosote, chamise, and red shank along 

desert slopes, to stands of ponderosa pine, mixed 

conifer, Jeffrey pine, and lodgepole pine. Signifi cant 

habitats include high-country conifer forests, 

live oak in deep canyons, a diverse cactus scrub 

community, pinyon juniper woodlands, and the 

fan palm oasis in Palm Canyon, the largest oasis of 

California fan palms in the United States.

Similar to the San Gabriel Mountains, the 

monument has a dramatic landscape rising abruptly 

from near sea level in the valley to the San Jacinto 

Peak at 10,834 feet. Five distinct “life zones,” 

from Sonoran Desert to Arctic Alpine provide 

exceptionally diverse biological resources. 

Higher elevations of the monument support 

subalpine vegetation such as lodgepole pine. The 

lodgepole pine habitat at the national monument 

differs in character from that found in the San 

Gabriel Mountains in that lodgepole pine habitat 

at Mt. San Antonio in the San Gabriel Mountains 

contain a variety of rare alpine and subalpine plants, 

partly related to the local geology. The area also 

supports an unusual subalpine forest of krummholz 

lodgepole pine, Pinus murrayana. Disjunct western 

juniper (Pinus occidentalis ssp. australis) also occurs 

here. 

Conclusion: Dry Coniferous Forest

No other national park unit in the South Pacifi c 

Border natural region or the Mojave-Sonoran Desert 

Region contains the types of Dry Coniferous Forest 

habitat found in the San Gabriel Mountains. Of 

the other comparably managed sites, the Santa 

Rosa and San Jacinto Mountains are most similar in 

character and quantity of habitat types. However, 

the San Gabriel Mountains maintain unique and 

unusual subalpine species not found in these 

locations. 

Aquatic Ecosystems Themes

The theme “Aquatic Ecosystems” is based on 

geomorphic and other physical aspects of aquatic 

ecosystems. The sub-theme “Streams” represents 

aquatic ecosystems with fl owing waters. The 

following sub-theme related to Aquatic Ecosystems 

is represented in the study area:

• Streams: Alluvial fan sage scrub, riparian 

habitat

STREAMS

Streams include fl owing waters with biological 

characteristics that are determined by the physical 

properties of the stream bed and by the nature of 

the watershed. The San Gabriel Mountain foothills 

contain some of the best remaining examples of 

alluvial fan sage scrub in the Los Angeles Basin. This 

type of vegetation is most common at the canyon 

mouths along the coastal side of the San Gabriel, 

San Bernardino, and San Jacinto Mountains. These 

fl oodplain systems are formed by extreme fl oods 

and erosion and features vegetation that has 

uniquely adapted to nutrient-poor substrates and 

subsurface moisture (Hanes et al 1989).

Since riparian areas were discussed in the 

previous section on River Systems and Lakes, the 
136 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

comparative analysis for this theme will focus 

on the alluvial fan sage scrub component of 

vegetation. Specifi c areas of well-developed alluvial 

fan vegetation within the study area include: the 

Big Tujunga Wash, the San Gabriel River Wash, San 

Antonio Creek, and the upper Santa Clara River. 

National Park Service Units

Existing national park units within the South Pacifi c 

Border and Mojave-Sonoran Desert Regions that 

represent the theme Streams include:

South Pacifi c Border Region

• Channel Islands National Park

• Golden Gate National Recreation Area

• Pinnacles NM

• Santa Monica Mountains National Recreation 

Area

• Whiskeytown-Shasta-Trinity National Recreation 

Area

Mojave-Sonoran Desert Region

• Death Valley National Park

• Lake Mead National Recreation Area

• Organ Pipe CactusNational Monument

• Saguaro National Monument

• Tonto National Monument

• Tuzigoot National Monument

Alluvial fan sage scrub is a distinct and rare plant 

community found on alluvial fans and fl oodplains 

along the southern base of the Transverse Ranges 

and portions of the Peninsular Ranges in southern 

California. As discussed in the previous chapter 

on signifi cance, alluvial fan sage scrub habitat is 

extremely rare. Excellent examples of remaining 

alluvial fan sage scrub are not found on any of 

the existing national parks in the Transverse and 

Peninsular Ranges. An analysis of ten of the most 

well-developed alluvial fan vegetation stands in Los 

Angeles, Riverside and San Bernardino Counties 

found that Big Tujunga Wash is one of three sites 

which exhibit the most species diversity and the San 

Gabriel River is among one of two sites that exhibits 

the greatest structural diversity (Hanes et al. 1989). 

San Antonio Canyon and the upper Santa Clara also 

contain excellent examples of alluvial fan sage scrub.

None of the national park units in the South Pacifi c 

Border Region or Mojave-Sonoran Desert Region 

which represent “Streams” contain signifi cant 

examples of southern California alluvial scrub 

vegetation. 

Comparably Managed Areas

Outside of the national park system other areas that 

represent streams include:

National Natural Landmarks (NNLs)

• Consumnes River Riparian Woodlands, CA

• San Ridge Wildfl ower Preserve, CA

• Canelo Hills Cienega, AZ 

• Patagonia-Sonita Creek Sanctuary, AZ

• Ramsey Canyon, AZ

National Forests and Bureau of Land 

Management Lands

• San Bernardino National Forest, CA

• Santa Ana Wash Area of Environmental 

Concern, CA

National Natural Landmarks (NNLs)

None of the NNLs in the South Pacifi c Border 

Region or Mojave-Sonoran Desert Region which 

represent the sub-them “Streams” contain 

signifi cant examples of southern California alluvial 

scrub vegetation. 

National Forests and Bureau of Land 

Management Lands

Of the remaining large, intact stands of alluvial 

fan sage scrub in southern California, most sites 

are located on privately-owned lands or lands not 

expressly managed for resource values or public 

enjoyment. Two protected area sites are located 

in the San Bernardino National Forest (NF) and on 

Bureau of Land Management (BLM) lands. 

The San Bernardino NF protects one of the largest 

intact stands of alluvial fan sage vegetation in 

southern California. Located in the pass between 

the San Gabriel and San Bernardino Mountains, 

the Cajon Wash alluvial fan sage scrub supports 

one of the most important populations of shortjoint beavertail (Opuntia basilaris var. brachyclada), 

occurrences of Plummer’s mariposa lily (Calochortus 

plummerae) and Parry’s spinefl ower (Chorizanthe 

parryi var. parryi), all of which are considered 

sensitive species. Public access to this area is via the 

Pacifi c Crest National Scenic Trail where it crosses 

Cajon Wash at Crowder Canyon, the Mormon 

Rocks Fire Station, and a nearby interpretive trail 

located in the northern section of the Cajon Wash 

alluvial fan sage scrub area (USFS 2005).

The Santa Ana Area of Critical Environmental 

Concern protects 755 acres of lands north of the 

City of Redlands, CA within the fl oodplains of the 
 Chapter 4: Suitability Cultural Themes 137

Santa Ana River and Plunge Creek. This area was 

set aside to provide special management for two 

federally listed endangered plant species associated 

with alluvial fan sage scrub, the Santa Ana River 

woolly-star (Eriastrum densifolium ssp. sanctorum) 

and the slender-horned spinefl ower (Dodecahema 

leptoceras). The Upper Santa Ana River Wash is 

primarily managed for water recharge, sensitive 

species habitat, and sand/gravel mining. The area is 

generally not accessible to the public, and the BLM 

parcels are surrounded by lands that are also closed 

to public use. 

Conclusion: Streams

No other national park unit in the South Pacifi c 

Border natural region or the Mojave-Sonoran Desert 

Region contains the alluvial fan vegetation unique 

to the Transverse and Peninsular Ranges of southern 

California. Of the comparably managed areas, the 

San Bernardino National Forest is the only publically 

accessible protected area with signifi cant alluvial fan 

sage scrub. 

The signifi cant alluvial fan sage scrub areas within 

the study area are primarily privately owned or 

managed by local water districts. However, several 

of these areas are adjacent to public lands and 

trails providing potential interpretive opportunities. 

The Santa Fe Dam Recreation Area along the 

San Gabriel River contains signifi cant alluvial fan 

sage scrub which is publicly accessible through 

recreational and interpretive trails. 

Cultural Themes

The NPS Thematic Framework (2000) for historical 

themes provides guidance on:

• evaluating the signifi cance of resources for 

listing on the National Register of Historic 

Places, for designation as national historic 

landmarks, or for potential addition to the 

national park system

• assessing how well the themes are currently 

represented in existing units of the national 

park system and in other recognized areas; and,

• expanding and enhancing the interpretive 

programs at existing units of the national park 

system to provide a fuller understanding of our 

nation’s past. (NPS 2000) 

Cultural Themes Represented in the 

San Gabriel Mountains

Themes represented by nationally signifi cant 

resources in the San Gabriel Mountains include:

• Expressing Cultural Values

• Expanding Science and Technology

EXPRESSING CULTURAL VALUES

The theme “expressing cultural values” covers 

expressions of culture – people’s beliefs about 

themselves and the world they inhabit. This 

theme also encompasses the ways that people 

communicate their moral and aesthetic values (NPS 

2000). The following topic related to Expressing 

Cultural Values is represented in the San Gabriel 

Mountains:

• Architecture: San Dimas Experimental Forest

Architecture

Architecture is focused on the development and 

expression of building design within the United 

States. It deals with the careers and works of 

leading architects, structures of outstanding value 

in design, the evolution of signifi cant architectural 

styles, and structures richly representative of 

particular types or geographical regions. 

The San Dimas Experimental Forest (SDEF) contains 

buildings and landscape features that are excellent 

examples of U.S. Forest Service architecture in the 

Pacifi c Southwest Region. Architects Blanchard 

and Maher designed the buildings in the region 

to refl ect California’s architectural heritage (wood 

buildings of the early days of the Mother Lode 

Country) (Jones & Stokes 2004). 

Facilities at the SDEF headquarters at Tanbark Flat 

include a laboratory/offi ce, residences, a mess 

hall, conference room, and several storage/utility 

buildings. Research/monitoring equipment includes 

rain gauges, stream gauges, debris dams, water 

quality samplers, a weather station, and a historical 

lysimeter complex. The lysimeter complex remains 

the largest structure of its type in the world. Other 

important CCC structures include stone landscape 

features

The SDEF retains the character, feeling, and 

association of its historic period. The SDEF has 

always functioned as an experimental forest and the 

built environment is largely unchanged since the 

SDEF was fi rst established in the 1930s. The Pacifi c 

Southwest Research Station and Angeles National 

continue to maintain the facility (USFS 1999a). 
138 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Another factor that makes the SDEF stand out is 

that a group of conscientious objectors (CO) was 

assigned to work at the SDEF through the duration 

of the war. Because the forest was short on workers 

during the war, the COs were able to do the work 

to maintain the SDEF (Jones & Stokes 2004). This 

story is not represented at comparable national park 

sites.

National Park Service Units

A variety of architectural styles are represented in 

national parks. Some buildings were representative 

of mainstream American architecture, while other 

architects’ designs were infl uenced by nature. 

“Rustic” design spread throughout the nation 

during the 1930s work-relief programs of the 

Depression (NPS 1986). 

The U.S. Forest Service has many rustic facilities of 

the Civilian Conservation Corps (CCC) era. Forest 

Service architecture is distinctive from region to 

region since building design was infl uenced by 

local conditions and building materials (Jones & 

Stokes 2004). The U.S. Forest Service Blanchard and 

Maher designs are similar to the NPS rustic design in 

California. 

There are many national park units in the west 

that have structures constructed by the CCC and 

other Depression era labor programs. In 1977, the 

NPS Western Regional Offi ce prepared a report 

on NPS Rustic Architecture. The report includes 

a comprehensive list of rustic structures in the 

NPS western region (now the Pacifi c West and 

Southwest Regions) that appear to qualify for listing 

on national register of historic places. The following 

national park areas include signifi cant facilities of 

the rustic architectural style in the West constructed 

by Depression era labor programs (NPS 2008b):

• Pinnacles National Monument, CA

• Bandelier National Monument, NM

• Crater Lake National Park, OR

• National Park Service Southwest Regional 

Offi ce, NM

Similar to the designs for the forest service 

administration buildings in the Pacifi c Southwest 

Region, national park architects combined native 

wood and stone with native styles to create 

structures that fi t naturally within the landscape.

All of the national park examples are different 

than the SDEF because they are not solely used 

for research. Also, the role of the conscientious 

objectors is unique to the SDEF. 

The Pinnacles National Monument East Entrance 

District includes features associated with the early 

park development and administration and the 

craftsmanship of the CCC and Works Progress 

Administration (WPA) programs. Types of facilities 

include small cabins now used for offi ces and a 

nature center, trails, and the dam that forms the 

Bear Gulch reservoir. This district is similar to the 

facilities at SDEF through its refl ection of California 

regional architecture and its chaparral setting. 

However, Pinnacles does not have the range of 

types of facilities represented at SDEF. Pinnacles 

National Monument offers interpretation of the 

CCC history while interpretive and educational 

opportunities of U.S. Forest Service architecture at 

the SDEF are not available. Public access is restricted 

and use of the SDEF is focused on scientifi c 

research.

Bandelier National Monument, Crater Lake National 

Park, and the NPS Southwest Regional Offi ce also 

contain signifi cant rustic architecture constructed by 

the CCC and other Depression era labor programs. 

These park and the regional offi ce structures 

refl ect different settings than that of the SDEF and 

Pinnacles National Monument. 

The Bandelier CCC Historic District includes the 

largest collection of CCC-built structures in a 

national park area that has not been altered by the 

addition of new structures within the district (NPS 

1977). The SDEF has more structures identifi ed than 

Bandelier. The architecture at Bandelier also differs 

from that of the SDEF since the buildings were 

designed and built to mimic a pueblo/small New 

Mexican village in keeping with rustic architecture 

principles. 

Crater Lake National Park was chosen for one of the 

most comprehensive rustic architectural programs 

undertaken by the NPS. Landscape architect Merel 

Sager layed out the administrative, residential 

and maintenance facilities and established design 

guidelines. Work on the site was done by CCC 

crews. The rustic character of the buildings was 

carried throughout a sequence of small stone-andtimber cottages. Although Crater Lake National 

Park has a collection of CCC structures, the natural 

setting is different than at SDEF and it does not 

have the range of types of facilities represented at 

SDEF (NPS 1977). 

The National Park Service Southwest Regional 

Offi ce in New Mexico is the largest known adobe 

offi ce building and one of the largest secular adobe 

buildings in the United States. The CCC cut and 

shaped the timbers, formed the thousands of adobe 

bricks, and erected the building, and the WPA put 
 Chapter 4: Suitability Cultural Themes 139

in the mechanical systems and other aspects of the 

fi nished product. Although this is a signifi cant NPS 

structure built by the CCC, it does not compare to 

the range and types of facilities constructed by the 

CCC at the SDEF.

Comparably Managed Areas

There are no national historic landmarks that 

represent the California Mother Lode Country 

architecture. There are no other national forest 

areas within the Pacifi c Southwest Region that 

contain the quality and quantity of the types 

of CCC-constructed rustic architecture facilities 

and landscape features representing the “wood 

buildings of the early days of the Mother Lode 

Country” as the SDEF in the Angeles National 

Forest. The building plans were adopted by other 

forests. Several California Department of Forestry 

buildings constructed during the 1930s were 

based on these plans. Examples of these remnant 

structures within the U.S. Forest Service and 

California Department of Forestry include:

• Tahoe National Forest, North Bloomfi eld 

Ranger Station: ranger residence and garage; 

Camptonville Ranger Station (Downieville 

Ranger District fi re station): offi ce, 2 residences, 

2 garages

• Modoc National Forest, Patterson Ranger 

District: garage

• Sierra National Forest, North Fork Ranger 

Station (Bass Lake Ranger District): supervisor’s 

residence 

• Shasta –Trinity National Forest, Weaverville 

Ranger Station, Mt. Shasta Ranger Station: 

headquarters offi ce building, ranger’s residence, 

auto shop, oil house, two warehouses, two 

large garages, and storage building

• Plumas National Forest, headquarters

• California Department of Forestry, Alma Forest 

Fire Station: kitchen-mess hall (Joslin 1995)

None of these sites contain the range, quality, and 

quantity of structures as the SDEF. Many of these 

buildings have been modifi ed and their uses have 

changed over the years. 

There are ten experimental forests/areas in the 

Pacifi c Southwest Region including the San 

Dimas Experimental Forest. There are no other 

experimental forests in the region that have historic 

structures based on the early U.S. Forest Service 

building plans and constructed by the CCC, in fact, 

most have few to no facilities:

• Caspar Creek, Challenge, North Mountain, 

Redwood, Stanislaus-Tuolumne, Swain 

Mountain: no facilities 

• Hawaii, Onion Creek, San Joaquin, and 

Teakettle: limited infrastructure/facilities

• Sagehen Experimental Forest: modern facilities

Conclusion: Expressing Cultural Values

The facilities at the SDEF are the best representation 

of the U.S. Forest Service architecture infl uenced 

by the wood buildings of the early days of 

the California Mother Lode Country. Among 

comparable national park areas, Pinnacles National 

Monument has CCC rustic architecture most similar 

to the SDEF. However, Pinnacles does not have 

the range of types of facilities, including those 

associated with research, represented at SDEF. Other 

California national forests have few remaining 

structures of the Blanchard and Maher designs, 

but there are no other sites, including experimental 

forests, that have the diversity of types, quality, 

quantity, and character as the SDEF.

Although the SDEF offers educational and research 

opportunities, interpretive opportunities are 

lacking. The SDEF could include interpretation by 

organizations that conduct fi eld trips or educational 

tours of the SDEF. The SDEF provides limited tours 

and scheduled visits for local youth. However, 

the SDEF does provide information to the public 

through a web site. This information includes some 

information about the CCC constructed facilities. 

EXPANDING SCIENCE AND TECHNOLOGY

This theme focuses on science, which is modern 

civilization’s way of organizing and conceptualizing 

knowledge about the world and the universe 

beyond. This is done through the physical sciences, 

the social sciences, and medicine. Technology is the 

application of human ingenuity to modifi cation of 

the environment in both modern and traditional 

cultures. Technologies can be particular to certain 

regions and cultures. The following topics related to 

Expanding Science and Technology are represented 

in the San Gabriel Mountains:

• Experimentation and Invention

• Technological Applications

• Scientifi c Thought And Theory

Within the San Gabriel Mountains, these topics are 

represented by the Mount Wilson Observatory and 

San Dimas Experimental Forest.

The Mount Wilson Observatory provides excellent 

representation of the sciences of astronomy and 
140 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

astrophysics. The National Park Service report 

entitled “National Survey of Historic Sites and 

Buildings report (1964)” included the section 

“The Arts and Sciences: Scientifi c Discoveries and 

Invention” that addressed astronomy. Twelve sites, 

including the Mount Wilson Observatory, related 

to the history of the science of astronomy were 

examined for designation under this theme. A 

subsequent national historic landmark theme study 

for Astronomy and Astrophysics (1989) included an 

NHL nomination for the Mount Wilson Observatory. 

The San Dimas Experimental Forest provides 

excellent representation of chaparral ecology. 

As described under the Natural History Themes, 

Land Ecosystems: Chaparral, the San Dimas 

Experimental Forest has been a leader in research of 

chaparral ecosystems and watersheds and provides 

superlative opportunities for scientifi c study.

The following comparative analysis is organized by 

the sciences: (1) astronomy and astrophysics and (2) 

chaparral ecology. 

Astronomy and Astrophysics: Mount 

Wilson Observatory

Experimentation and Invention

The Mount Wilson Observatory represents 

experimentation using new scientifi c instruments 

and methods for studying the sun and the 

universe. The Mount Wilson Observatory provided 

many signifi cant contributions to the science 

of astronomy and our understanding of the 

universe. Many astronomers and other scientists, 

including Edwin P. Hubble and Albert Michelson, 

conducted signifi cant research and experiments at 

the Observatory. Astronomy questions including 

the nature of sunspots, the temperature and 

composition of stars, and the structure and origin 

of the universe were addressed at the Mount 

Wilson Observatory. Astronomers and physicists 

made astrophysics a modern science. George Ellery 

Hale proved that sunspots are actually regions of 

reduced solar temperature while Albert Michelson 

conducted experiments to accurately measure the 

speed of light. 

Experimentation often required the invention 

of new technology. Inventions related to the 

observatory include, the fi ve large telescopes 

designed by Hale, and new technologies, including 

new large scale telescopes, refl ectors, refractors and 

cameras to study distant astronomical objects. 

Technological Applications

George Ellery Hale’s vision of a modern observatory 

combining a solar telescope and a large refl ecting 

telescope was achieved at the observatory, making 

it a model for modern observatories. Hale’s 

telescopes laid the technological foundation for all 

large modern telescopes (NPS 1989). For example, 

the fl exible optical system for the 150-foot solar 

telescope developed by Hale became a model for 

future large refl ectors. 

Hale designed the telescopes and other equipment 

to be fl exible to accommodate changing needs and 

uses. The 100-inch Hooker refl ector was used to 

produce the fi rst detailed photographs of “spiral 

nebulae.” Hale estimated that the Hooker refl ector 

could photograph at least two million nebulae. 

Today, the Hooker refl ector is equipped with a 

modern adaptive optics system and is used in a 

variety of high-resolution studies.

Scientifi c Thought and Theory

Before establishing the Mount Wilson Observatory, 

George Hale worked at the Yerkes Observatory 

in Wisconsin. Through his work at Yerkes, Hale 

believed that the future of astronomy required the 

study of astrophysics, the term he invented. Hale 

needed to establish a mountaintop observatory 

that would combine a solar telescope and a large 

refl ecting telescope in order to understand the 

physical processes that took place in the sun and 

other more distant stars. Hale explained this when 

he wrote: “The story of the origin of the sun and 

its development is illustrated in stars of many 

types which are no less important to a thorough 

understanding of its physical constitution than is 

a direct investigation of solar phenomena (NPS 

1989).”

In the 1920s, many scientists at Mount Wilson 

Observatory were able to gather important data 

about the stars and universe. In 1920, Albert 

Michelson determined the diameter of the star 

Betelgeuse to be 215,000,000 miles. In 1923 

Edwin Hubble studied the Cepheid variable star in 

Andromeda Galaxy providing proof that the Milky 

Way is only one of many galaxies. In 1929, Hubble 

used the 100-inch Hooker refl ector to gather data 

that showed the universe to be in a regular state of 

expansion. This provided the fi rst clues to the origin 

of the universe and corrected Einstein’s belief that 

the universe was static. Later, direct evidence for the 

“Big Bang” theory was collected (NPS 1989).

National Park Service Units

There are no units in the national park system that 

represent astronomy. Under a previous thematic 

framework for cultural resources, national park 

units were listed under the subtopic of “Physical 

Sciences.” There were no park units identifi ed 
 Chapter 4: Suitability Cultural Themes 141

for “Astronomy.” Two sites were identifi ed for 

representation of “Physics,” Benjamin Franklin 

National Memorial (Affi liated Area) and Edison 

National Historic Site. Edison National Historic Site 

was also identifi ed for the theme, “Chemistry.” 

Comparably Managed Areas

Several studies, documents, and properties listed 

in the National Register of Historic Places included 

sites for consideration under this topic. More than 

100 sites, including laboratories, workshops, homes 

and sites associated with the lives and achievements 

of famous American astronomers were included 

in the theme study list. Observatories/laboratories 

related to astronomy that are national historic 

landmarks (NHLs) include:

• Cincinnati Observatory, Cincinnati, OH

• Hubble, Edwin, House, San Marino, CA

• Lowell Observatory, Flagstaff, AZ

• Hale Solar Laboratory, Pasadena, CA

• Stellafane Observatory, North Springfi eld, VT

• Gaithersburg Latitude Observatory, 

Gaithersburg, MD

• University of Illinois Observatory, Urbana, IL

• Vassar College Observatory, NY

These facilities, including Mount Wilson 

Observatory, are owned and managed by nongovernmental institutions. Since 1986, Mt. 

Wilson Observatory has been operated under 

an agreement with the Carnegie Institution of 

Washington by the Mount Wilson Institute, a 

non-profi t corporation whose mission focuses 

on scientifi c research, historic preservation, 

astronomical education and public outreach. In 

2003, Mount Wilson Observatory’s 99-year lease 

was renewed by the U.S. Forest Service. The Friends 

of the Mount Wilson Observatory Association works 

to provide public appreciation and education about 

the observatory.

The Lowell Observatory in Arizona, the Cincinnati 

Observatory in Ohio, and the Hale Solar Laboratory 

in California are the NHLs that are most comparable 

to the Mount Wilson Observatory. Experiments 

conducted at these facilities produced data and 

results that complemented those at Mount Wilson. 

At the Lowell Observatory, experiments were 

conducted to help prove that the universe was 

expanding. The Cincinnati Observatory’s publication 

of Stellar Proper Motions, which provided data in 

determining the structure and rotation of the Milky 

Way, also provided data for theories, such as the Big 

Bang. George Ellery Hale worked at the Hale Solar 

Laboratory, which he designed, during the latter 

part of his life. These facilities are still in operation 

for research or education.

Since the 1930s, Mount Wilson has provided many 

opportunities for visitors. Open to visitors during 

weekends and holidays, the observatory provides an 

educational program, exhibits, and regular lectures 

by the staff and visiting astronomers. Public use of 

the 60 inch telescope continues today. The museum 

interprets the astronomical knowledge in the 1930s 

and knowledge today. Visitors can view the historic 

Hooker telescope inside the dome. Picnic areas and 

Skyline Park, operated by the U.S. Forest Service, are 

open to the public. The Mount Wilson Observatory 

Association provides walking tours. 

The Mount Wilson observatory continues to provide 

opportunities for scientifi c study in the fi eld of 

astronomy. Several guest institutions including the 

University of California, Berkeley; the University of 

California, Los Angeles; Georgia State University; 

University of Illinois at Champaign-Urbana; and the 

University of Southern California have facilities on 

the observatory. The Mount Wilson Observatory 

Association provides support to the Observatory. 

Similarly, Lowell Observatory and Cincinnati 

Observatory offer public access. Lowell offers a 

range of guided and other specialized tours and 

telescope viewing. It also has a visitor center, 

museum, and exhibits. Many observatories 

are affi liated with universities and also provide 

opportunities for research. However, the long 

history of the observatory, with its public and 

educational opportunities, and the combination 

of the observatory facilities and other amenities 

provided by the U.S. Forest Service makes the 

Mount Wilson Observatory unique compared to 

these other sites.

The Stellafane Observatory in Vermont, the 

Gaithersburg Latitude Observatory in Maryland, 

the University of Illinois Observatory in Illinois, and 

the Vassar College Observatory, in New York are 

other national historic landmarks that represent 

astronomy. 

In addition, there are other important observatories 

and facilities that have not been designated 

national historic landmarks for their representation 

of astronomy. After the Mount Wilson Observatory 

location became impacted from light pollution in 

the Los Angeles Basin, Hale founded the Palomar 

Observatory in San Diego, which includes the 200-

inch refl ector. Its completion in 1948 made it the 

largest refl ecting telescope in the world. At the Lick 

Observatory near San Jose, California, the 36-inch 
142 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Clark refractor was the fi rst large telescope placed 

on a site chosen for its astronomical advantages, 

rather than for convenience. 

Mauna Kea Observatories on the Island of Hawaii 

hosts the world’s largest modern astronomical 

observatory, with telescopes operated by 

astronomers from eleven countries. The telescopes 

include the largest optical/infrared telescopes in the 

world (the Keck telescopes), the largest infrared 

telescope and the largest submillimeter telescope 

in the world (Institute for Astronomy, University of 

Hawaii).

Chaparral Ecology: San Dimas 

Experimental Forest

Experimentation and Invention

The San Dimas Experimental Forest represents 

“experimentation and invention” related to 

chaparral ecology. Study of the Big Dalton Canyon 

and San Dimas Canyon watersheds was the fi rst 

major streamfl ow erosion study by the California 

Forest and Range Experiment Station and only the 

fourth such investigation of its kind in the world. 

The long record of studies conducted at the SDEF is 

unmatched in this region (Jones & Stokes 2004).

The initial research and experiments at the SDEF 

were focused on increasing water yields from 

watersheds. Scientists were able to monitor rainfall 

and runoff from the 1930s to 1950s with a network 

of rain gauges, stream gauges, and weather 

stations. Water consumption by various plant 

species was studied in lysimeter and runoff plots. 

Using the data gathered, scientists then attempted 

to increase water yield in the Bell and Monroe 

watersheds through vegetation manipulation (Jones 

& Stokes 2004).

After a fi re in 1960 had burned the research 

watersheds, the research was focused on postfi re 

rehabilitation, then on runoff and erosion. Scientists 

conducted experiments to control runoff. In 

subsequent decades, studies focused on ecosystemlevel issues, including air pollution, soil genesis, 

postfi re plant and animal succession and recovery. 

Soil research on the SDEF has included some 

pioneering studies on the “hydrophobic,” or waterrepellent, layer that forms after fi res (Jones & Stokes 

2004).

Technological Applications

Research and monitoring equipment were 

developed for the long-term studies at the 

SDEF. The Lysimeter facility at SDEF (tunnel and 

instrument room), completed in 1937, is still 

the largest of its kind in the world. Rain gauge 

networks as described earlier were developed to 

accurately measure precipitation and fl umes were 

developed to measure and withstand debris fl ows. 

Most of this equipment, including the lysimeter 

facility, are still intact and are continuing to be used 

for research (Jones & Stokes 2004).

Scientifi c Thought and Theory

The SDEF, established in 1933, has one of the 

longest – if not the longest – record of research on 

chaparral ecosystems. Long-term studies (described 

earlier) have yielded data for learning how to 

control runoff and for the identifi cation of postfi re 

soil conditions (Jones & Stokes 2004). 

National Park Service Units

There are several national park units in California 

that include chaparral ecosystems (See discussion 

under “Natural History Themes”). The California 

Mediterranean Research Learning Center (CMRLC) 

promotes study of chaparral ecology and includes 

the following national park units:

• Santa Monica Mountains National Recreation 

Area (NRA)

• Channel Islands National Park

• Cabrillo National Monument

As described in the natural history themes section, 

the CMRLC program is new and its research differs 

from the watershed studies of the SDEF. The SDEF 

has a longer record of research than the more 

recently established CMRLC.

Comparably Managed Areas

There are ten experimental forests/areas in the 

Pacifi c Southwest Region including the San Dimas 

Experimental Forest. One experimental area and 

one experimental forest are most similar to the 

SDEF in their research focus: 

• North Mountain Experimental Area (NMEA), 

San Bernardino National Forest

• Caspar Creek Experimental Watershed, 

Redwood National Forest

The North Mountain Experimental Area (NMEA), 

established in 1964, is the only U.S. Forest Service 

Experimental Area that is located in a chaparral 

ecosystem. The NMEA research differs from that of 

the SDEF. Whereas the SDEF studies have focused 

on watersheds, including hydrologic processes 

and postfi re rehabilitation, the NMEA research 

is focused on prevention and control of forest 

and range fi res. The SDEF has a longer record of 

research on chaparral ecosystems than the NMEA .
 Chapter 4: Suitability Cultural Themes 143

Caspar Creek Experimental Watershed, established 

in 1962, also conducts watershed studies, but it is 

located on the northern coast of California and has 

different vegetation than that of the SDEF. 

There are opportunities to interpret the research 

and history of the SDEF from nearby facilities of the 

ANF, including the San Gabriel River Ranger District 

offi ce in Glendora.

Conclusion: Expanding Science and 

Technology

There are no units in the national park system 

or areas managed by other entities that have 

the combination of resources as the San Gabriel 

Mountains has in its representation of the theme 

“Expanding Science and Technology.” Together, 

the Mount Wilson Observatory and the San Dimas 

Experimental Forest have provided decades of 

scientifi c information that is unmatched. There are 

no units in the national park system that represent 

astronomy and astrophysics. There are few NHLs 

that compare to the Mount Wilson Observatory. 

Likewise there are few national park units and other 

sites that represent chaparral ecology, and no other 

site contains the long record of research that has 

been collected at the SDEF.

OVERALL SUMMARY: SUITABILITY OF THE SAN 

GABRIEL MOUNTAINS

The NPS has determined, based on the combination 

of resource values in the San Gabriel Mountains, 

that this area is suitable for inclusion in the national 

park system. The San Gabriel Mountains have 

resources that are outstanding representations of a 

wide range of both natural and cultural themes not 

found in other national park units or comparably 

managed sites. 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 architecture, astronomy, chaparral ecosystems, 

and watersheds. 

The signifi cant natural and cultural resources of the 

San Gabriel Mountains are primarily managed by the 

U.S. Forest Service as part of the Angeles National 

Forest. A few smaller areas with resource signifi cance 

are managed by other agencies and organizations 

including Los Angeles County Parks, which manages 

most of the Devil’s Punchbowl formation for 

public enjoyment and education, and the Friends 

of the Mount Wilson Observatory which provides 

interpretive and educational programs about the 

signifi cance of the observatory. While many of the 

foothill areas in the San Gabriel and Antelope Valleys 

are protected by various conservancies and local park 

districts, some areas remain unprotected.

Although the U.S. Forest Service’s resource 

management provides substantial resource 

protection, comprehensive education and 

interpretation of the signifi cance of the San Gabriel 

Mountains is lacking in many areas (e.g., chaparral 

ecosystems, geologic processes, watershed resources 

and research), primarily due to funding and staffi ng 

limitations. National Park Service expertise and 

emphasis on interpretation and education and 

visitor management would expand and enhance 

the visitor experience in the San Gabriel Mountains 

and would allow for more comprehensive education 

and interpretation on all of the interpretive themes 

related to its national signifi cance.

The overall combination of resource values 

represented by the San Gabriel Mountains is 

not comparable to any other existing national 

park unit. The national park unit that is closest 

in representation to the combination of themes 

represented by the San Gabriel Mountains is the 

Santa Monica Mountains NRA. However, based on 

the theme-based comparative analysis, there are 

outstanding qualities represented in the San Gabriel 

Mountains which are not comparatively represented 

in the Santa Monica Mountains. The unique geologic 

composition of the San Gabriel Mountains differs in 

rarity, quality and quantity from mountain systems 

at Santa Monica NRA. With its adjacency to the 

San Andreas Fault and long history of research, the 

San Gabriel Mountains is one of the best locations 

to observe and study active mountain building 

and plate tectonics. The highly erosive geologic 

processes taking place in the San Gabriel Mountains 

has created river systems quite distinct from those 

found in the Santa Monica Mountains. Additionally, 

the extreme elevation changes in the San Gabriel 

Mountains represent a wider diversity of habitats. 

The San Gabriel Mountains contain rare examples 

of southern California subalpine vegetation not 

represented by any other national park unit in 

the South Pacifi c Border or the Mojave-Sonoran 

Desert natural regions. Finally, the cultural resource 

representation of the San Dimas Experimental 

Forest architecture, science and technology and the 

signifi cance of the Mt. Wilson Observatory to the 

study of astronomy are not represented in the Santa 

Monica Mountains. 

The combination of themes represented in the 

San Gabriel Mountains and its close proximity 

to greater Los Angeles metropolitan region with 

over 15 million residents, means that this area has 

excellent potential for expanding opportunities for 

interpretation, education, and scientifi c study.
144 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Puente-Chino Hills

NATURAL HISTORY THEMES REPRESENTED IN 

THE PUENTE CHINO HILLS

The Puente-Chino Hills contain signifi cant resources 

that represent the “Land Ecosystems” natural 

history theme.“

LAND ECOSYSTEMS THEMES

The following sub-themes related to Land 

Ecosystems are represented in the study area:

 Chaparral (shrubs and evergreen forest 

trees): Coastal sage scrub

 Dry Coniferous Forest: Walnut woodlands 

and forests.

CHAPARRAL 

Chaparral ecosystems include broad-leafed, mainly 

evergreen, species of shrubs or low trees, occurring 

as dense scrub or woodland. The Puente-Chino hills 

contain a high level of biodiversity and outstanding 

examples of California coastal sage scrub, one 

of the most endangered plant communities in 

California.

National Park Units 

Existing national park units within the South 

Pacifi c Border include htat represent the theme 

Chaparral include:

• Whiskeytown-Shasta-Trinity National Recreation 

Area

• Pinnacles National Monument

• Santa Monica Mountains National Recreation 

Area

• Cabrillo National Monument

Mojave-Sonoran Desert Region parks that represent 

the theme Chaparral do not contain coastal sage 

scrub habitat.

Three classifi cations of coastal sage scrub are typical 

of the Southwestern ecoregion of California as 

classifi ed by Paleobotanist Daniel Axelrod: Venturan, 

Riversidian, and Diegan. The Puente-Chino Hills, 

which are a transition zone, contain Venturan and 

Diegan coastal sage scrub communities not typically 

represented in any one protected area in southern 

California. Over 10,000 acres of coastal scrub are 

located in the portion of the Puente-Chino Hills 

included in the study area (Puente Hills Landfi ll 

Native Habitat Preservation Authority 2007; Davis, 

et al. 1994, Axelrod 1978).

Pinnacles NM and Whiskeytown-Shasta-Trinity NRA 

contain northern and central California affi nities of 

coastal sage scrub habitat. Areas managed by the 

National Park Service that protect southern affi nities 

of coastal sage scrub similar to those found in the 

Puente-Chino Hills include Santa Monica Mountains 

NRA (approximately 32,000 acres of Venturan 

coastal sage scrub) and Cabrillo NM (approximately 

840 acres of Diegan coastal sage scrub) (Davis, et al. 

1994). 

The Puente-Chino Hills contain a signifi cant portion 

of designated critical habitat for the federally listed 

threatened coastal California gnatcatcher, a species 

dependent on coastal sage scrub habitat.

The combination of resources values associated with 

coastal sage scrub within the Puente-Chino Hills is 

not represented in the existing southern California 

national park units. No other existing national park 

unit contains both Venturan and Diegan coastal 

sage scrub. Nor does any existing unit contain 

designated critical habitat for the California coastal 

gnatcatcher. Evolutionary studies completed for 

species in the Los Angeles Basin area indicate that 

species in the Puente-Chino Hills are evolutionarily 

different from species in the Santa Monica 

Mountains which represent the southern extent of 

northern species (Personal communication, Robert 

Fisher, USGS 2007). 

Comparably Managed Areas

Outside of the national park system other areas that 

represent chaparral (coastal sage scrub) in California 

include:

State and Local Parks

• Chino Hills State Park

• Crystal Cove State Park

• Puente Hills Landfi ll Native Habitat Preserve

Private Preserves 

• Santa Rosa Plateau Ecological Reserve

• Starr Ranch Audubon Sanctuary

State and Local Parks

Chino Hills State Park (SP) and Crystal Cove SP both 

contain coastal sage scrub habitat. Chino Hills SP 

contains primarily Diegan coastal sage scrub, and 

Crystal Cove SP contains Venturan coastal sage 

scrub. Although just outside of the study area to 

the east, Chino Hills SP is a critical component of 

the larger Puente-Chino Hills biological corridor. 

The park primarily functions as an open space 

reserve. It contains almost 4,000 acres of coastal 

sage scrub and critical habitat for the California 
 Chapter 4: Suitability Cultural Themes 145

coastal gnatcatcher. Recreational opportunities 

include hiking, biking, and wildlife observation. 

While the Chino Hills State Park contains similar 

coastal sage scrub resources to the Puente-Chino 

Hills, protection of the study area coastal sage 

scrub would expand and enhance the protection 

of this habitat within the larger wildlife corridor. 

Numerous studies document the benefi ts of habitat 

connectivity to ensure healthy wildlife populations

(Vandergast et.al. 2007). For example, 90% of the 

habitat in Chino Hills SP was damaged by the 2008 

Freeway Complex fi re. Having adjacent open space 

and habitat was critical for the recovery of wildlife 

in Chino Hills SP. 

Crystal Cove SP is located in Orange County along 

the coast between the cities of Newport Beach 

and Laguna Beach. The park protects hundreds of 

acres of Venturan coastal sage scrub and provides 

numerous recreational opportunities on trails and 

beaches. Crystal Cove SP contains coastal sage 

scrub more similar in character to the Santa Monica 

Mountains NRA.

Located within the study area, the Puente Hills 

Landfi ll Native Habitat Preserve protects important 

coastal sage scrub habitat in the Puente Hills. 

Private Preserves

The Santa Rosa Plateau Ecological Reserve is located 

at the southern end of the Santa Ana Mountains in 

southwest Riverside County. Managed by Riverside 

County Regional Park and Open-Space District and 

the Nature Conservancy, the Reserve consists of 

8,300 acres and protects unique ecosystems such 

as Engelmann oak woodlands, riparian wetlands, 

coastal sage scrub, chaparral, bunchgrass prairie 

and vernal pools. A very small area of the reserve is 

designated critical habitat for the California coastal 

gnatcatcher. The bunchgrass prairie is one of the 

fi nest examples remaining in California. 

The Starr Ranch Sanctuary is a 4,000 acre preserve 

owned and operated by the National Audubon 

Society. It is located in Orange County in the 

foothills of the Santa Ana Mountains. The Starr 

Ranch contains Diegan coastal sage scrub and 

critical habitat for the California coastal gnatcatcher. 

Although not open to the general public, research 

and education are core components of the ranch 

mission and public education programs are regularly 

held for school, groups and the general public. 

Staff research is integrated into all public education 

programs. 

Although both private preserves contain excellent 

examples of coastal sage scrub, neither location 

contains the quantity and diversity of coastal sage 

scrub found in the Puente-Chino Hills. 

Conclusion: Chaparral

Of the national park units, Santa Monica Mountains 

NRA is most comparable to the Puente-Chino Hills. 

However, the Puente-Chino Hills differ considerably 

in character as they contain both a transitional area 

for coastal sage scrub and signifi cant acreage of 

critical habitat for the California coastal gnatcatcher. 

The Chino Hills SP and the Puente Hills Landfi ll 

Native Habitat Preserve manage coastal sage scrub 

resources in the Puente-Chino Hills. Management 

by the NPS could expand and enhance current 

protection efforts by California State Parks and 

the Puente Hills Landfi ll Native Habitat Preserve, 

particularly in the areas of coordinated resource 

management and education. Protected status for 

the Puente-Chino Hills within the study area would 

ensure long term protection of the larger corridor’s 

biodiversity. 

Although both of the private preserves analyzed 

contain excellent examples of coastal sage scrub, 

neither location contains the quantity and diversity 

of coastal sage scrub found in the Puente-Chino 

Hills. 

DRY CONIFEROUS FOREST 

This sub-theme includes belts of coniferous forest 

and woodland dominated by Douglas-fi r, ponderosa 

pine, and pinyon-juniper. At its lower limits these 

forests give way to steppe or chaparral ecosystems. 

California walnut woodlands and forests are 

included in this theme. As stated in the previous 

chapter, some of the best remaining stands of 

California walnut-dominated forests and woodlands 

south of Ventura County are located in the PuenteChino Hills. 

National Park Units

The following national park unit within the South 

Pacifi c Border Region represents the theme dry 

coniferous forest:

• Santa Monica Mountains National Recreation 

Area

Mojave-Sonoran Desert Region parks that represent 

the theme Chaparral do not contain California 

walnut woodlands.

The historic distribution of California walnut 

woodlands and forests is limited to the areas 

between the Santa Clara River drainage in Ventura 

County on the north and the Chino Hills on the 

south. Outside of this range California walnut trees 
146 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

tend to be interspersed with other tree species such 

as oaks. Therefore the only national park unit in the 

South Pacifi c Border region that contains California 

walnut woodlands is Santa Monica Mountains 

NRA. Approximately 450 acres of California walnut 

woodlands of are located in the Santa Monica 

Mountains NRA.

The California Natural Diversity Database (CNDDB) 

Inventory has on record approximately 17,000 acres 

of remaining California walnut woodlands and 

forests. Of these remaining woodlands, the best 

remaining stands south of Ventura County are those 

located in the Puente-Chino Hills. Approximately 

1,700 acres, or 10% of the CNDDB Inventory, are 

located in the study area in the Puente-Chino Hills 

(Quinn 1990, CDFG 2006). 

Comparably Managed Areas

Outside of the national park system other areas that 

represent dry coniferous forest (California walnut 

woodlands) include:

National Forests and Wildlife Refuges

• San Bernardino National Forest

• Los Padres National Forest

• Hopper Mountain National Wildlife Refuge

State and Local Parks

• Chino Hills State Park

• Puente Hills Landfi ll Native Habitat Preserve

• Debs Park

National Forests and Wildlife Refuges

At the northern limit of distribution, the Los 

Padres NF contains approximately 660 acres of 

California walnut woodlands. Near the southern 

limit of distribution, the San Bernardino NF contains 

approximately 230 acres of California walnut 

woodlands (CDFG 2006).

The Hopper Mountain National Wildlife Refuge 

contains nearly 400 acres of California walnut 

woodland at its northern limit. Both the Hopper 

Mountain National Wildlife Refuge and Los Padres 

NF protect excellent examples of California walnut 

woodlands at their northern extent. These stands 

have adapted to their local site characteristics 

and differ from the Los Angeles County stands in 

morphology and canopy structure. Los Angeles 

and Orange County walnuts typically have multiple 

trunks. On mesic sites they often grow into more 

shrub-like habits (Quinn 1990). 

Walnut woodlands in the San Bernardino NF are 

in small quantity and do not represent the best 

examples of this species at its southern distribution 

(Quinn 1990; CDFG 2006).

State and Local Parks

State and local parks that contain excellent 

examples of walnut woodlands include Debs Park, 

Chino Hills State Park, and the Puente Hills Landfi ll 

Native Habitat Preservation Authority (Habitat 

Authority). 

Debs Park in the Arroyo Seco/Monterey Hills area 

of Los Angeles contains extensive stands of walnut 

woodlands. Recreational uses and facilities in this 

portion of the park are minimal. The emphasis is on 

the enjoyment of nature. 

Chino Hills State Park contains the largest acreage 

of California walnut woodlands stands protected 

by a conservation agency, approximately 1,100 

acres (Quinn 1990, CDFG 2006). However, the 

1,700 acres found in the Puente-Chino Hills in the 

study area are also of the highest quality and would 

enhance and expand protection of this rare habitat. 

While many of the study area stands are protected 

by the Habitat Authority, most are located on 

private lands. Additionally, other sites that protect 

walnut woodlands do not have the quality of 

walnut woodlands found in the Puente-Chino 

Hills. The quality of walnut woodlands and forests 

is measured by extensiveness. Although there are 

important walnut woodlands and forests at Debs 

Park and in other areas of the study area such as 

California State Polytechnic University at Pomona 

and the San Jose Hills, these woodlands are 

scattered for considerable distances. The area of 

Brea between Los Angeles and Orange County has 

not been urbanized and has an extensive stretch 

of woodlands and forests thus having the highest 

quality of this type of habitat (Quinn 2009). 

Conclusion: Dry Coniferous Forest

No other national park unit in the South Pacifi c 

Border Region contains the quantity and quality of 

California walnut woodland habitat found in the 

Puente-Chino Hills. Although the Chino Hills SP and 

the Habitat Authority protects California walnut 

woodlands similar in quality and quantity, the rarity 

and quality of this habitat type requires protection 

of the remaining signifi cant stands, most of which 

are located in portion of the Puente-Chino Hills 

within the study area. 
 Chapter 4: Suitability Cultural Themes 147

OVERALL SUMMARY: SUITABILITY OF THE 

PUENTE-CHINO HILLS

The NPS has determined, based on the character, 

quantity and quality of resource values in the 

Puente-Chino Hills, that this area is suitable for 

inclusion in the national park system. The PuenteChino 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. 

Lands suitable for coastal sage scrub habitat 

(lands below 500m in elevation) account for 

nearly half of the southwestern ecoregion, yet the 

proportion of these lands managed for protection 

of biodiversity is relatively small (Davis et.al. 1994). 

Higher elevations tend to have more protection 

(e.g. national forest lands). Although coastal sage 

scrub is protected at several national park units, no 

other unit protects a signifi cant amount of the rare 

California walnut woodlands.

Of the comparably managed sites, the Chino Hills 

State Park is the closest in resource quality and 

character to the Puente-Chino Hills portion of the 

study area. Although many similar resources are 

protected, Chino Hills State Park is part of the 

larger biological corridor of the Puente-Chino Hills. 

Protected status for the Puente-Chino Hills within 

the study area would expand existing resource 

protection and ensure long term protection of the 

larger corridor’s biodiversity.

Additionally, recent studies have found that areas 

which retain adequate genetic variability are more 

likely to facilitate both adaptive and non-adaptive 

evolution as the environment changes. The Los 

Angeles Basin was identifi ed as an evolutional 

hotspot in need of based on its high levels of 

genetic diversity (Vandergast et.al. 2008). 

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. 

Statewide California Walnut Woodland and Forest Distribution (Source: CDFG 2006)
148 Draft San Gabriel Watershed and Mountains Special Resource Study & Environmental Assessment 

Summary: Suitability

Based upon evaluation of the study area resources 

and their relative quality, character, and rarity, the 

National Park Service has determined that the San 

Gabriel Mountains and Puente-Chino Hills portions 

of the study area are suitable for inclusion in the 

national park system. Together, the two areas 

contain a combination of themes and resources 

not found in any national park unit or comparably 

managed area. 

Table 7: Summary of Areas Suitable for Inclusion in the National Park System

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 

protection of the larger Puente-Chino Hills corridor biodiversity.

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.