The Altar Valley Conservation Alliance is a collaborative conservation organization founded in 1995, and incorporated as a 501(c)3 not-for-profit organization. Just southwest of Tucson, Arizona, the Altar Valley comprises approximately 610,000 acres of Sonoran desert grassland, some of the most biologically rich and ecologically threatened biotic communities in the world. Private ranches work side by side with federal, state and local agencies to manage the valley, which is the largest unfragmented watershed in Pima County, outside of the Tohono O’odham Nation to the west. This collection is an archive of reports and other documents specific to Alliance activities.
San Simon Watershed Assessment and Restoration Plan
USDA Agricultural Research Service
Abstract: This paper describes a partnership of the Bureau of Land Management (BLM), the Bureau of Reclamation (Reclamation), the University of Arizona, and the Arizona Department of Water Resources (DWR). The partnership is assessing and restoring the San Simon watershed, a sub-basin in the Upper Gila River Watershed. EPA selected that watershed as one of 12 Clean Water Action Plan Showcase Watersheds. The San Simon River incised early in the 20th century. Primary land uses within the San Simon Watershed include recreation, a designated OHV use area, farming, and livestock grazing. BLM installed grade control structures on the San Simon River and tributaries, beginning in the 1930s. The purpose of the grade control was to halt channel incision and degradation of the watershed land resources. In all, there are 19 major detention dams, several dikes, and earth structures. They all require assessment to determine effectiveness and condition for repair/maintenance. The Safford Field Office proposes to complete an assessment of the San Simon River watershed as a prerequisite to a community-based planning effort setting the future direction and management of the watershed. The assessment will answer three questions: 1. Are the existing grade control structures effective? a) Are the structures hydraulically and geomorphically effective? b) Is maintenance of the existing structures cost-effective? 2. Would additional grade control structures hasten the restoration of the river and tributary channels, and aid in the recovery of the watershed? 3. How does the Resources Inventory and Assessment of the uplands and the San Simon channel depend upon the grade control structures?