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<br />There are many studies of the variation of precipitation by itself Dry periods identified as <br /> <br /> <br />drought have been of concern for a long time. Tannehill (1947) recognized that all geographic <br /> <br /> <br />areas have periods of drought and that the 1930s were really unusually dry in the central U.S. In <br /> <br /> <br />the later 1970s a workshop summarized by Rosenberg (1978) recognized the 1930s, 19505 and a <br /> <br /> <br />portion of the 1970s have allied to drought problems with which the U.S. has struggled. In a <br /> <br />summary of streamflow (ST) the USGS (1989) has identified periods of drought as 1930-42, <br /> <br />1949-57, 1958-70 and 1976-82. Research based on tree rings by Meko et al. (1995) has indicated <br /> <br />several periods since the mid 1500s in the western U. S. have been drier than the present 30-year <br /> <br />average. A study by Edwards and McKee (1997) of drought in the United States in the 20th <br /> <br /> <br />centruy indicates that much of the U.S. has fewer drought events in the past 25 years. A summary <br /> <br />of drought globally in the peirod 1900-1995 has been given by Dai et al. (1998). <br /> <br />In this report the analysis tool used by Edwards and McKee (1997) will be introduced to <br /> <br /> <br />describe both drought and wet events for periods in Colorado. Information is included here <br /> <br /> <br />related to precipitation, snowpack and streamflow which give a broader view of drought and wet <br /> <br />periods. <br /> <br />3 <br />