©2003 American Meteorological Society

ecadal drought and wetness extremes punctu-ated the twentieth-century climate over the cen-tral and western United States. A strong pluvial in the early twentieth century covered a large portion of the West and lasted for more than a decade. Severe, sustained droughts afflicted most of the United States in the 1930s and 1950s (Fig. 1a). These moisture re-gimes have had an enormous impact on the economy and environment of the United States. The early twen-tieth-century pluvial-biased estimates of stream dis-charge in the Colorado River basin contributed to unrealistic allocation of Colorado River water in sub-sequent decades (e.g., Stockton 1975; Reisner 1986; Brown 1988). The Dust Bowl drought of the 1930s interacted with poor land-use practices and led to on