El Rio Preserve riparian rehabilitation & community recreation

Abstract

The Sonoran Desert is a unique biodiverse landscape of approximately 100,000 square miles in Southwestern United States. It is characterized by seasonal monsoon rains in both the summer and winter that sustain some 2,000 different plant species, making it a comparatively lush desert.

Because of the Sonoran Desert’s geographic location and seasonal precipitation patterns, a variety of biomes can be found in the region, including tundra, coniferous forest, temperate deciduous forest, grassland, chaparral, desert, thornscrub, and tropical forest (Arizona-Sonora Desert Museum, 2017). Within these biomes are corridors of riparian communities, which are areas of watercourses that create unique habitats. In the Southwest, many of these riparian watercourses are currently ephemeral and only fl ow temporarily throughout the year. These xeroriparian habitats (dry riparian) are largely and increasingly ephemeral because of human disturbances. Watercourses that once were perennial, such as the Santa Cruz River, now flow primarily only during the monsoon rains.

Riparian communities are critical components in the network of biomes and habitats in the Sonoran Desert. They provide corridors for the movements of plants and animals, and sustain unique species in the desert that require more water. These communities are also beautiful, lush landscapes that are often enjoyed by humans for their oasis-like qualities; trails, camping and picnicking spots, and scenic points-of-view are often found along watercourses. The El Rio Preserve in Marana, Arizona is such a riparian community tucked along the banks of the Santa Cruz River. It is part of a chain of other regionally-significant habitats, and presents opportunities for both habitat and human recreation. Many species of plants and animals have found refuge at El Rio, including invasive species. Its origins as a former borrow pit, however, make it a disturbed xeroriparian landscape that could benefit from rehabilitation strategies.

The following Master’s Report presents a process and design for El Rio. A majority of the work was done in collaboration with the Town of Marana. Public participation was a large component of the project, which informed many design decisions. A comprehensive literature and case review, and ongoing site assessments also contributed to the final design and rehabilitation strategies.