Water Resources Impacts on Tribal Irrigation Projects

Abstract:

The Bureau of Indian Affairs (BIA) Branch of Irrigation and Power provides oversight and technical support to select irrigation projects and systems on tribal lands. The BIA provides operations and maintenance support for 16 irrigation systems. To make the best use of limited resources, the BIA must incorporate climate change impacts on hydrology and water management for these irrigation systems in the coming decades. The 16 irrigation projects discussed here are divided into three climatological regions: the Pacific Northwest Region, the Greater Rocky Mountain Region, and the Western, Southwest, & Navajo Region. Significant climate projections that impact irrigation systems in one or more of these regions include increased temperatures and evaporative demand, earlier snowmelt and runoff, an increase in floods, an increase in heavy precipitation events, an increase in the frequency and intensity of droughts, and declining water supplies. Some irrigation projects are particularly vulnerable to these climate impacts because they are in already water-stressed areas or areas in which water resources are over-allocated. Other irrigation projects will have to adjust their storage and water management strategies to accommodate changes in the timing of streamflow. Overall, though, the BIA will be better able to assist tribal nations by incorporating expected climate impacts into their water resources management practices.