Rillito River

The Rillito River (Spanish pronunciation: [']; Spanish "Little River") flows from east to west across the northern boundary of the City of Tucson from the confluence of Tanque Verde Creek and Pantano Wash to the Santa Cruz River 7.2 miles (11.6 km) away. The Rillito River Park runs along the north and south banks of the river from Interstate 10 to North Craycroft Road.^[2]

History

Water once flowed perennially and supported substantial growth of cottonwoods, willows, and mesquites. Historical accounts of conditions on the Rillito approximately 100 years ago describe a tree-lined, narrow river with dense vegetation winding throughout the riverbed and vicinity. The river channel carried abundant water that supported early irrigation projects. In the 1850’s, the river channel was lined with a continuous oasis of trees and grasses along the riverbanks and flood plain. The river path was obstructed by numerous beaver dams that ponded the water and encouraged the development of riparian wetlands. Increasing appropriation of surface and ground water to support expansion of agriculture and growing urban populations resulted in the transformation of the Rillito from a river with perennial surface and subsurface flows to a dry wash with stabilized banks which flows only ephemerally in response to storm runoff. Because of this change, stands of native riparian habitat are rare, as they are throughout Pima County.

References

 This article incorporates public domain material from the United States Army Corps of Engineers website http://rfcd.pima.gov/largefiles/corps/elrioantiguo/rioant.pdf (retrieved on 2016-01-18).