Understanding uncertainties in future Colorado River streamflow

Abstract

The Colorado River is the primary water source for more than 30 million people in seven rapidly growing, mostly arid American states and Mexico. The Colorado River water supply system, which consists of two large reservoirs (Lakes Mead and Powell) and numerous smaller reservoirs, is already stressed because of growing water demand and an ongoing drought that is outside the historical norm of twentieth-century climate variability (Fulp 2005; USBR 2011a). Concerns have been voiced that this recent prolonged drought could be a harbinger of a permanent shift to a drier climate (Seager et al. 2007; Barnett and Pierce 2008, 2009; Overpeck and Udall 2010; Cayan et al. 2010; USBR 2011a, among others).