Laserfiche WebLink
<br />2. The early 1900s were indeed one of the wettest periods on record. The 1970 to 1995 <br />period was also relatively wet. <br /> <br />3. The reconstructions verify the conclusion of the Siebert Report, the 1870-1900 period <br />was indeed quite dry. It was most likely much drier than the 1930-1960s period. <br /> <br />4. There are drought periods in the late 1500s, late 1600s, late 1700s and mid and late <br />1800s that are most likely more severe than the 1930-1960s dry period. <br /> <br />Figure VI-l shows a 25 year smoothed or filtered average156 of the Lees-B reconstruction of <br />the 2006 Woodhouse paper. I like using a 25 year smoothed average because of its relevance to <br />reservoir operations and the 1922 Compact. Because of the large amount of storage in Lake Powell <br />and Lake Mead and the 10 year commitment under Article ill (d) of the 1922 Compact, the 25 year <br />filtered average approximates Mead and Powell operations and can be used to flag periods where <br />the Upper Basin could have problems meeting its downstream commitments and periods of extended <br />shortages in the Lower Basin. <br /> <br /> 20000 <br /> 18000 <br /> 16000 <br /> 14000 <br />c 12000 <br />c <br />c <br />..... <br />.. <br />.... <br />Q) 10000 <br />Q) <br />LL <br />Q) <br />.. <br />(J 8000 <br /><t <br /> 6000 <br /> 4000 <br /> 2000 <br /> 0 <br /> 1500 <br /> <br />25 Year Moving Average Lees "B" 1514 -1998 <br /> <br />COMPACT NEGOTIATIONS <br /> <br /> <br />SEVERE AND SUSTAINED <br />DROUGHT STUDY PERIOD <br /> <br />DROUGHT IDENTIFIED <br />BY SIEBERT REPORT <br /> <br />1550 <br /> <br />1600 <br /> <br />2000 <br /> <br />1650 <br /> <br />1700 <br /> <br />1750 <br />Year <br /> <br />1800 <br /> <br />1850 <br /> <br />1900 <br /> <br />1950 <br /> <br />FIGURE VI-I: Natural Flows at Lee Ferry <br /> <br />J56For this paper, the 25 year smoothed or filtered average is the average of the current and previous 24 years. <br /> <br />Page -69- <br />