Sonoran Desert Preservation: An Open Space Plan for the City of Phoenix, Arizona SESSION SERIES: North Sonoran Collaborative
James P. Burke and Joseph M. Ewan	© & Author Info

Abstract

In January of 1998 the Sonoran Preserve Master Plan was completed by the City of Phoenix Parks, Recreation and Library Department (PRLD). Driving this effort is the fact that the city is located amid some of the most beautiful and biologically rich desert in the world--the Sonoran Desert--and at an increasing rate this valuable resource is threatened. Within the Sonoran Desert, bi-modal rainy seasons support diverse and rich plant communities making it the most lush desert in the world. This paper presents a brief history of preservation efforts and the planning and design process used in the development of the master plan and suggests a more comprehensive and collaborative approach to urban open space design in and around metropolitan Phoenix, Arizona.

Introduction In January of 1998 the Sonoran Preserve Master Plan was completed by the City of Phoenix Parks, Recreation and Library Department (PRLD). Driving this effort is the fact that the city is located amid some of the most beautiful and biologically rich desert in the world--the Sonoran Desert--and at an increasing rate this valuable resource is threatened. Within the Sonoran Desert, bi-modal rainy seasons support diverse and rich plant communities making it the most lush desert in the world. This paper presents a brief history of preservation efforts and the planning and design process used in the development of the master plan and suggests a more comprehensive and collaborative approach to urban open space design that merges both "place making" and "rule making."

Figure 1: South Mountain Park

History of Preservation Efforts

Preservation of large areas of Sonoran vegetation, specifically Palo Verde-Saguaro communities typically found on bajadas and mountain slopes, is a long-standing tradition for the city. The first effort began in 1924 to acquire South Mountain Park (Figure 1). At the time, Phoenix covered five and one-half square miles and boasted a population of 38,500 (figure 2). City leaders had the vision to acquire what they believed to be the last prime recreation site for picnicking, horseback riding, and hiking near the city at the time. This area lay seven and three-quarter miles beyond the city limits and was known as the Salt River Mountains. This area includes two mountain ranges, the Gila-Guadalupe and Ma Ha Tuak, with Mount Suppoa as the highest peak at 2,690 feet (downtown Phoenix is at an elevation of 1,117 feet above sea level). Civic leaders encouraged President Coolidge to sell 13,000 acres to the city for $17,000 and in 1925 the first patent for the park was secured by presidential decree. The original master plan was developed by the National Park Service. While not full implemented, many of the elements the structures, constructed by the Civilian Conservation Corps, called for in the original plan, are still standing and used. Today, the 16,500-acre South Mountain Park is the largest city park in the nation and part of Phoenix's Mountain Preserve System. Visitation has soared from 36,000 a year in 1924 to serve over three million a year in 1990 (Burke 1997).

Figure 2: Phoenix 1920 5.1 Sq. Miles, Population 29,033

Figure 3: Phoenix 1970 247 Sq. Miles, Population 584,303

In the 1970s the city had grown to 248 square miles with population in excess of 584,000 (Figure 3). Valley horsemen realizing development was fast approaching the southern slopes of Squaw Peak, the northern limit of the city at that time, took the current Mayor and City Council on a morning ride to demonstrate the beauty and recreational potential of the Phoenix Mountains. After a detailed master plan was completed by Van Cleeve and Associates in 1972, the City Council established the Phoenix Mountain Preserves. Of the 9,700 acres targeted by the Van Cleeve document, today 7,500 acres have been acquired for $70 million. The Phoenix Mountains include features such as Shaw Butte, North Mountain, and the Dreamy Draw Recreation Area which annually attracts one-half million visitors per year to the trails, parks, and desert parks. This area also contains the Squaw Peak Summit Trail, believed to be the most popular summit trail in the country with over one-half a million hikers per year. Past preservation efforts were primarily informed by three criteria: visual prominence, steep slopes, and land ownership. While these efforts have made a significant contribution to what makes a 'there' in Phoenix, they unfortunately where not informed by what Edward Abbey called the "cancer of growth."

Figure 4: Phoenix Mountain Preserves

The Sonoran Preserve Master Plan

In 1997, nearly two-thirds of the region's residents rated desert preservation efforts as only fair or poor (Morrison 1997). The City of Phoenix, committed to maintaining its leadership role in desert preservation and to preserving the quality of life in the Valley of the Sun, developed the Sonoran Preserve Master Plan. This plan built on numerous preservation efforts and research prepared by the City of Phoenix, Maricopa County Associations of Governments (MAG), citizens, and Arizona State University. Today, the plan includes 20,000 acres of relatively undisturbed Sonoran Desert (Figure 5). Making this opportunity possible was the annexation of 110 square miles of undisturbed desert lands. Nearly two-thirds of these lands are owned by the Arizona State Land Department and held in trust to benefit public schools as well as other public institutions. Current uses include cattle grazing and a limited number of sand and gravel mining operations.

Figure 5: Sonoran Preserve Master Plan

Unique from past preservation efforts, focused specifically on mountains, this plan incorporates diverse physiographic features or landscape types. Mountains are included in keeping with the long-standing preservation tradition along with desert washes, creosote flats, and bajadas (transition lands between mountains and flats).

In 1995 the MAG Regional Council adopted the Desert Spaces Plan. The concept for this plan was to provide a nonregulatory framework toward establishing a regional open space network. The plan defined regionally significant mountains, rivers, washes, and upland desert. While the scale of this effort was not specific or appropriate for the City of Phoenix, this effort did provide a regional context and identify regionally significant open space.

The planning process for the Sonoran Preserve incorporated traditional planning techniques (citizen participation, inventory, and analysis) with landscape ecological theory. Instead of designating a preserve based primarily on visual prominence, slope, and land ownership, the Sonoran Preserve Master Plan suggests maintaining a system that functions biologically (maintains species diversity and ecological processes) yet can also act as a recreational resource. A specific goal was to avoid the oversights of the past that created islands of open space separating preserved areas from the greater community and the larger natural environment. The recommendations made in the Sonoran Preserve Master Plan represents a significant departure from previous planning efforts that considered the natural environment but focused preserve efforts on visually prominent lands that were less suitable for development. In the early planning stages, a series of studies commissioned by the PRLD developed an ecological database that informed the preserve planning process.

In 1996 the PRLD developed three concepts for the Phoenix Sonoran Preserve to illustrate several ways that the potential preserve in the Desert View Tri-Villages could be configured. Since the planning at this point was conceptual, a precise acreage was not designated. The three concepts demonstrated a range of approaches to open space acquisition and built onto open space lands already owned or controlled by the PRLD.

The three concepts that went through the public review process were general configurations of possible preserve forms and are as follows:

1. The concentrated concept contains the preserve in one large contiguous parcel that maximizes habitat and wildlife benefits (low perimeter/area ratio). This concept lessens the emphasis on the recreational access and creates the greatest opportunity for isolated natural areas.
2. The dispersed concept integrates the preserve into developed areas allowing a great number of users access from home and work. This could be called a "backyard approach," creating a greater potential for negative impact on wildlife and habitat (highest perimeter/area ratio) while increasing neighborhood pedestrian and bicycle access.
3. The semi-concentrated concept holds a middle ground between the concentrated and dispersed concepts. It has significant areas set aside for conservation while allowing for reasonable recreational access from adjacent developments. All habitat/vegetation types are included (moderate perimeter/area ratio).

The three concepts were presented at two open houses hosted by the PRLD. Notices were mailed to a list of interested citizens, including organizational contacts for the Mountain Preservation Council, the Mountaineers, the Sierra Club, the Audubon Society, the Central Arizona Homebuilders Association, the Realtors Association, and the Valley Partnership. Respondents ranked the three concepts in order of preference from most to least preferred. The concentrated concept was selected as the most preferred by 61 percent of the respondents, followed by the semi-concentrated concept selected by 32 percent of the respondents as being most preferred. Only five percent of the respondents most preferred the dispersed concept. Many of the respondents articulated that preserving the health of the environment should be of the utmost importance.

In 1997 the PRLD began another series of studies with ASU's SPLA focused on wildlife (large and small terrestrial mammals, bats, avian species, and reptiles). The initial year of the study focused on washes and in the subsequent two years consider hillsides, bajadas, and creosote flats. The information on species composition, abundance, richness, and diversity will help inform the continuing refinement of the preserve plan as well as provide baseline data for future evaluation of the health of the preserve.

Another partnership in 1996 between the PRLD and ASU included the Multidisciplinary GIS Initiative that developed a Geographic Information System database and computer modeling program. The ability of the GIS database to integrate both graphic and descriptive information has become a valuable tool in managing the growing amount of available data for the 130 square mile area.

In addition to the database that included specific information on natural factors, ecological principles were gleaned from these studies and the PRLD literature review and then used to develop the plan. The following principles were recommended:

1. Hydrologic processes should be maintained. Watercourses should remain unfragmented and corridors should be as wide as possible.
2. Landscape patches should be as large as possible. Patches provide numerous ecological benefits that include ameliorating microclimate, providing habitat, and absorbing rainfall.
3. Connectivity of patches and corridors should be maintained. This facilitates wildlife survival and movement.
4. Unique mosaics of land forms and vegetation types should be included in the preserve. Mosaics provide important physical conditions that support wildlife species diversity. They are also are visually interesting.
5. Diverse mosaics should be integrated into the developed environment. This expands the mobility and available area for wildlife. It also facilitates contact with nature which is beneficial to human ecology.
6. The preserve should be considered at multiple scales. The function of a preserve cannot be sustained within a vacuum. For example, at a regional scale, the preserve's connectivity to other significant undisturbed desert lands should be provided.

The Sonoran Preserve Master Plan calls for the practice of development to be evaluated, specifically the grading and drainage ordinances. Currently, and typically practiced, developers submit a subdivision plan that eliminates natural washes in favor of structural channels and detention basins. This method of handling storm water runoff from developments has left little natural desert except within dedicated public open space. The city is working with the local flood control authority to develop nonstructural flood plain management guidelines based on an understanding of the complete hydrologic systems rather than on a site-by-site basis. Accommodating the natural migration of washes (a commonly observed occurrence in the southwest where soils associated with washes tend to be highly erodible) will greatly expand the notion of preservation beyond dedicated parcels of Sonoran Desert. Nonstructural guidelines are expected to be incorporated into the city's ordinances.

In addition, the city is developing design guidelines for development of private lands adjacent to the proposed preserve. Recognizing the investment needed to realize the Sonoran Preserve, estimated at over $225 million, it seems obvious to have adjacent development relate to the preserve. Unfortunately this has not been the common response for residential development in the past. Typically, the subdivision is designed with walled backyards adjacent to the preserves; this creates a physical barrier, gives future homeowners a false sense of private ownership of the preserve, and often times concentrates invasive flora and fauna adjacent to the preserve edge. The PRLD's current thinking about the preserve edge is analogous to the approach of coastline development. The preserve can be buffered from private development with a zone of public space that can accommodate trails or promenades and, in some instances, single-loaded streets. Preferably private development would also open up to the preserve with courtyards, patios, and plazas. Blurring the edge of the preserve can have both ecological and social benefits (fig. 8).

The City has also begun to develop an acquisition strategy to acquire the 20,000 acres include in the Plan. To assist in this process the City has developed a GIS based system to analyze the various acquisition strategies that could be adopted and their relation ship to City finances and urban growth. This system allows the City to build a strategy based on the various funding techniques available to the City and test it based on different funding levels and urban growth rates.

Figure 8:Development Concepts

Conclusion

This master plan creates a framework for a preserve system that builds on Phoenix's history of setting aside significant Sonoran Desert land for preserve recreation, open space, and environmental/educational opportunities. The successes and mistakes of the past have been used as building blocks for the development of this plan and the designation of the preserve boundaries. In addition to the master plan, changes to existing city ordinances such as flood plain management and subdivision development will be needed to fully embrace the goals of the plan. The Phoenix Sonoran Preserve System can compliment the city's existing Mountain Preserve System and build on its success by adding additional types of lands that are of ecological significance, will benefit wildlife, define the urban setting, positively impact human health and well being, and expand recreational opportunities. Continued collaboration is a necessity to transform this vision into a grand reality.

References

Burke, James. 1997. Recreation on Municipal Lands: A Case Study of 73 Years of Sonoran Desert Preservation. Arizona Game and Fish Department. Phoenix, Arizona

City of Phoenix. 1970. An Open Space Plan for the Phoenix Mountains. Phoenix Arizona

City of Phoenix. 1994. The Desert Preserve Preliminary Plan. Phoenix Arizona

City of Phoenix. 1998. The Sonoran Preserve Master Plan. Phoenix Arizona

Ewan, J. and Rebecca Fish Ewan. 1996. Cave Creek Wash Preservation Boundary Study. Arizona State University: College of Architecture and Environmental Design Herberger Center for Design Excellence. Tempe, Arizona

Gart, Jason. 1996. Papago Park: A History of Hole-In-The-Rock from 1848-1995. Pueblo Grande Museum Occasional Papers No. 1. Phoenix, Arizona.

Johnson, Ryan. 1997. What Matters in Greater Phoenix, 1997 Indicators of Our Quality of Life. Morrison Institute for Public Policy, Arizona State University. Tempe, Arizona

Maricopa Associations of Governments. 1995. Desert Spaces: An Open Space Plan for the Maricopa Associations of Governments. Phoenix, Arizona.

Maricopa Associations of Governments. 1998. Maricopa Associations of Governments 1998 Projections. Phoenix, Arizona.

James P. Burke, Deputy Director
City of Phoenix
Parks, Recreation & Library Department
Phoenix, AZ 85003
Email: jburke@ci.phoenix.az.us

Joseph M. Ewan, ASLA, Assistant Professor
Arizona State University
School of Planning & Landscape Architecture
Tempe, AZ 85287-2005
Email: joe.ewan@asu.edu