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<br />002863 <br /> <br />. <br /> <br />'. <br /> <br />QJ>') <br />f J -~ <br />. {))A/.' / . <br />-L..ildt, f' <br />:l: I. <br />J <br /> <br />TO: <br /> <br />FROi'l: <br /> <br />Randy Seaholm <br /> <br />DATE: <br /> <br />August 19, 1985 <br /> <br />SUBJECT: <br /> <br />Computation of 602 (a) storage ~n CRSM/CRSS for <br />simulation purposes. <br /> <br />Tilis memorandum briefly analyzes PL90- ')3 7, Section 602 (a) <br />storage requirements as described in the CRSS-Systems OverVIew. <br />::oection 602 (a) was written into PL 90-537, the Colorado River <br />Basin ProJect act, to help protect CRSP reservoirs while <br />mandating the development of "Criteria for Coordinated Long-Range <br />Oi?eration of: the Colorado River Reservoirs "in order to comply <br />with the "Law or the River." Attached are title VI of PL 90-537 <br />and the Coordinated Long Range Operating Criteria along with <br />references to sections from other legal documents which provide <br />t{l" legal basis and means for computation of 602(a) storage. The <br />purpose of 602 (a) and the related equalization of storage <br />between Lakes Powell and Mead was to provide an equitable <br />apportionment of water between the Uppe!:" and Lower Basins thus <br />lessening trle adverse impacts from Article III (e) of the <br />Colorado River Compact. A detailed discussion of events related <br />to this subject can be round in Reclamation's 1978 update of the <br />Hoover dam documents. <br /> <br />Computat.ion ot the 602(a) storage volume in CRSS/CRSM is <br />handled in the following manner at t'ne beginning of each calendar <br />year. <br /> <br />1) Number of years of sedimen't acculllulation in Powell = <br />current year - 1963 (year of closing). <br /> <br />2) Average Annual Upper Basin Depletion = Average Annual <br />Depletions tor the next n years + Average Annual Upper <br />Basin Evaporation, wl1ere <br /> <br />n = the number of years in the critical period of <br />record which is presently 1953-1964 or 12 years, <br />It is extremely important to note that this <br />critical period varies w~th the level of upper <br />basin depletion and thus the assumed level of <br />maximum depletions which is presently 5.8 maf. <br /> <br />704 <br />crsm/crss <br />