Pomona Valley: Assessing Natural Boundaries and Greenspace

A joint research project by Montgomery McIntosh and Terence Young, California State Polytechnic University, Pomona and Richard Worthington, Pomona College


The purpose of this project is to provide a brief cultural history of the Pomona Valley and to assess its natural boundaries. In particular, the mapping exercise seeks to identify which areas or cities are potentially underserved by greenspace and to suggest the need for coordinated management of the Valley’s open space. The authors hope that the maps and report will stimulate pubic awareness of the need for additional funding for parks and other greenspaces in the underserved communities of the Pomona Valley.
The Pomona Valley is a large sloping alluvium within the Santa Ana watershed of the Los Angeles basin.  In the upper reaches of the Valley, among the sloping San Jose foothills of the San Gabriel Mountains, water surfaces in numerous springs and artesian wells. Valley Grasslands, Coastal Sage Scrub, Oak Woodlands, and Chaparral were once widespread plant communities occurring within the Pomona Valley. The size of the Valley is approximately 250 square miles and is divided between three counties - Riverside, San Bernardino, and Los Angeles- and eleven cities (see “Cities in Pomona Valley” map).

Pomona Valley

          Santa Ana Watershed

Context Map

Census map

Cities in Pomona valley

Contour map

                                    Greenspace in Pomona Valley               Greenspace and Population Density                 Underserved Population Groups

The authors thank the Andrew W. Mellon Foundation for a New Directions in Faculty Research Grant (Pomona College), and the
support of the San Gabriel and Lower Los Angeles Rivers and Mountains Conservancy for making this project possible.


Long before Spanish setters arrived, small bands of Native Americans, known as the Tongva (or Gabrielenos as they were later referred by the Spanish), lived within the Pomona valley.  Early Spanish settlers encountered the majority of Tongva villages near the foothills where water came to the surface.  Specifically, these villages occurred along the banks of San Jose Creek in what is today known as Genesha Park, in North Pomona (near Orange Grove Ave), Claremont and San Dimas (at the foot of Indian Hill), and scattered about the Cucamonga hills.  The Tongva traveled across the Pomona Valley gathering locusts and grasshoppers, and hunting coyotes, deer, raccoons, squirrels and snakes .  They would venture into the foothills for the seasonal gathering of red manzanita berries, mountain cherries and Chia seeds (see the
Cal Poly Rain Bird Ethnobotany Learning Center).  The Tongva, whom settled in the foothills and valley flatlands, bartered their basketry and obsidian blades for the salt, smoked fish and dentalia of the coastal Chumash Indians (Pomona Centennial-Bicentennial Committee, 1976; Lothrop,1988). 

Under the leadership of Junipero Serra, Spanish soldiers and Franciscans established the San Gabriel Mission (1771) and the San Bernardino Mission (1810), and laid the foundations for the settlement of the Pomona Valley.  The mission lands extended east from Pomona and Claremont to San Bernardino, and southward to San Pedro, covering an area 21 miles wide and 42 miles long (Lothrop, 1988).  In 1822, Mexico became independent of Spain and empowered the governor of California, Jose Figueroa to begin apportioning the lands, which had been administered for more than six decades by the mission fathers. Large ranches owned by the Palomeres and Vijar families spanned much of the Valley by the 1840s.  These ranches subsisted by raising cattle and sheep, and cultivating wheat, corn, and bean crops. The 1848 cession of California by Mexico, however, brought radical change to the people who lived on ranches in southern California.  Although these changes were perceptibly slow, ranchers began to incrementally subdivide their properties to smaller ranches. In the 1850s, Americans from the East Coast and an increasing number of immigrants began settling the region. Settlements and townships developed around the old ranchos, such as the Chino ranch, and Cucamonga ranch (Historic Land Company, 1920).  By the early 1880s the construction of the Southern Pacific Railroad prompted the development of town sites in key locations including land adjacent to what would become the Pomona rail depot (Lothrop, 1988).


From the 1880s to the 1920s, despite a series of droughts, floods, and freezes, Southern California became the “Orange Empire.”  Pomona was at the center of the Citrus Triangle, which extended from Santa Ana west to the San Fernando Valley and east to Redlands and Riverside (King, 2001).  The exponential rise of citrus production in Southern California, however, was eventually doomed by the scarcity of water and land costs, as well as the lack of markets during WWII and governmental support (Lothrop, 1988).

Pomona Valley was originally not part of the Metropolitan Water District because water was plentiful and natural replenishment of groundwater was adequate. With the appearance of real-estate subdivisions in the 1920s, and more significantly after World War II, the Metropolitan Water District annexed Pomona Valley into the district in 1949.  Around1940 the distribution of land in the Valley consisted of 4,289 acres of urban land and 26,559 acres of non-urban land, including general agriculture, open use, rural railroads and streets, and small farms and tree crops. Between 1940 and 1949 the population within the Valley increased 43% from 34,639 to 49,690 . The push to semi-rural and suburban areas in the 1950s, made the Pomona Valley an attractive prospect for imported capital, new business, and construction activity supported by a growing suburban residential economy (Dienes, 1949, pp. 31,37,85). 

The rapid suburbanization of the Pomona Valley since the 1940s has created a need for inter-city coordination to balance planning and development with respect to water resources and recreational facilities (Dienes, 1949).  The City of Pomona led the state to develop the concept of the shared use of school grounds and parks through the Joint Use of Facilities Agreement of 1943 (Lothrop, 1988).  This agreement allowed a major park improvement bond issue in 1956 for $850,000.  Recreational facilities were further enhanced within Pomona and surrounding cities with the state’s purchase of Puddingstone Dam and Reservoir, which in 1970 became a 1,975-acre facility called Bonelli Park.  The development of large regional parks such as Bonelli Park exemplify the type of inter-city coordination which is required for multiple communities to be well-served by large scale greenspace.   As evident in the “Greenspace and Population Density” map, other communities within the Pomona Valley, such as Corona, south Pomona, Norco and Chino, have been marginalized for park facility allocation and are consequently underserved by more localized greenspace. 

A similar bond measure to the one passed in 1956 was approved for the city of Los Angeles in 1996;  Prop K generates $25 million per year to fund the acquisition, improvement, construction and maintenance of city parks and recreation facilities.  Prop K bond funding is allocated through a competitive process in which community-based organizations (CBO) as well as city agencies and other public entities must submit requests for funding.  It is difficult however, for some cities and community-based organizations without the resources and expertise to acquire funding.  GIS can play a significant role in analyzing communities underserved by greenspace. The Sustainable Cities Program at the University of Southern California has used a GIS to reveal fundamental patterns of inequality in the distribution of Prop K funding in the city of Los Angeles. Low-income households and communities of color in Los Angeles are apt to be relegated to ‘park poor’ neighborhoods, while wealthier neighborhoods are more likely to have abundant green space provided by public funding (Wolch, Wilson, and Fehrenbach, 2002). Moreover, since property values tend to increase in areas with more greenspace, the result has been a growing disparity of wealth (Diamond, 1980).   The rapid growth patterns of moderate-to-low density development and exponential population growth in the greater Los Angeles area (including Pomona Valley), has increased the need for  developing parks and recreation facilities.  Los Angeles has an average of 4 acres per 1,000 residents (City of Los Angeles, 2001), well below the National Recreation and Parks Association’s standard of 6.25-10.5 acres per 1,000 residents (2000).


The boundary of the Pomona Valley was defined using historic mapping data from 1970, watershed boundaries, and topographic data (Landis - Fairchild Aeromaps, 1970; ESRI vendor data, CSPU GIS lab).  The Pomona Valley boundaries were then  finalized by combining city and county boundaries, the Santa Ana watershed boundary, and contour maps of the area.

Greenspace within Pomona Valley was derived from land ownership data from the Rivers and Mountains Conservancy. An analysis map was made to compare acres of greenspace to population density within Pomona Valley. To do this, the zonal statistics analysis function was used to find the average people per square mile (with an allocation of 100 meter cell sizes) in relation to greenspace.  The allocation layer was then converted to a polygon to derive the size of each polygon. We then used the field calculator to see the average amount of people living within each polygon. One can see from the greenspace analysis map the relationship of population density and greenspace within the Pomona Valley; south Ontario, Chino, Rancho Cucamonga, and Fontan are visibly underserved by greenspace. (see "Population Density and Greenspace Map").


Further GIS analysis could be performed to derive more analysis maps revealing the specific communities that are underserved by greenspace at a variety of scales. More detailed analyses could provide greater validity for allocating park funding to underserved communities within Riverside and San Bernardino counties, in particular Norco, Corona and parts of Chino, Pomona, and Ontario.   These communities could then develop ballot initiatives for park bond measures like Proposition K.  It would also be helpful to be able to make the analysis maps interactive within the website for those interested in viewing more information.


City of Los Angeles, Department of City Planning, 2001, http://www.ci.la.ca.us/PLN/

City of Los Angeles. 1970. Pomona Valley, Los Angeles CA: Landis Fairchild Eromaps, Inc.c.

Diamond, Douglas B. 1980. “The relationship between Amenities and Urban Land Prices,” Land Economics. 56:21-32.

Dienes, Kalman. 1949. Problems of Transition in Pomona Valley, Pomona CA.: Progress-Bulletin Publishing Co., pp. 31, 37, 85.

Historic Record Company. 1920. History of Pomona Valley, Los Angeles CA

King, William. 2001. Pomona: The Citrus Empire, Carlsbad, CA: Heritage Media Corp., pp. 56-60.

Landis - Fairchild Aeromaps, Inc. 1970. Pomona Valley, courtesy of California Division of Highways.

Lothrop, Gloria. 1988. Pomona: A Centennial History, Northridge, CA: Windsor Publications, Inc.

National Recreation and Parks Association, “National Park Land Standards,” 4-18-2000. http://www.ci.big-spring.tx.us/Recreation/park_standards.html

Rivers & Mountains Conservancy (RMC), Los Angeles: base map data- parklands, Thomas Bros. data, 10meter DEM and aerial photos.

Wolch, J., Wilson, J.P., Fehrenbach, J. 2002. “Parks and Park Funding in Los Angeles: An Equity Mapping Analysis,” Los Angeles , CA: Sustainable Cities Program, University of Southern California. www.usc.edu/dept/geography/ESPE/documents/publications_parks.pdf


Terence Young, Assistant Professor of Geography, California State Polytechnic University, Pomona: http://www.csupomona.edu/~tgyoung/

Richard Worthington, Professor of Politics, Pomona College: http://www.politics.pomona.edu/worthington.html