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Ou15JS -19-- Engineering Data .. 1, Discrepa~cies in basic data. Data concerning the flow. of the Colorado River at Lee Ferry are presented in Appendix 1 by year~ for the period 1897~1943. These consist of estimate~ by the Bureau of Reclamation for the period l897~1921, and of records by the U. S. Geological Survey for subsequent years. Colorado notes that the U. S. Geological Survey has also published ectimates for the period l897~l92l whioh differ in most years; and in some by substantial amounts, fro" the Bureau of Reclamation estimates present;ld in the Report. Such discrel'onoies in the basic data reported by cooperating agenc~es are confusing, nod h~ve required the Engineering Conunittee of the Upper Colorado River Basin Compact COllllllission to undertake correlation studies and make its own estimations. ., .. 2, Natural Conveyanoe Losses above Lee Ferry. The s~called virgin flow. of the Colorado River at Lee Ferry was calculated in Appendix I, for each year of the 189701943 period, as the sum of: (1) the actual flow as estimated or recorded, plus (2) the quantity of water estimated to have been consumed by the lands, irrigated within the natural basin and to have been diverted from the natural basin for use outs ids. Expressed as an average for the period 1897u1943, tt~ virgin flow of the Colorado River at Lee Ferry, thus caloulated, is reported at 16.270,000 acre feet annunJJ.yo With respect to the quantities of water estimated to have been utilizea upstream from Lee Ferry, attention has previously been dir~cted to the fact that the quantities employed in Appendix I (See Paragraph 5, "Detailed Views s:l.d Recommendations" above) to calculate virgin flows differ from the estimates of existing uses reported in the substantiating material. In both estimates the evaluations were made as of project sites, _ the quantities of water consumed by the irrigation of lands within the natural basin abnve Lee Ferry being calculated by multiplying the number of acres irrigated by a unit rate of consumptive use considered to be applicable in accordance with prevailing temperaturesl and the quantities diverted from tho natural ba"i~ being measured at project sites. .' Colorado notes, however, that the Report, disrege.rding the natural channel losses incident to the conveyan~e of w8ter downstream to Lee Ferry, applieff ths full amount of the estimated upstreem uses, or the straa~ depletions at project sites, to the flow at Lee F8~~Yo This erroneous aRsumption of the Report, that water, if not used and consumed ~pstrgam. wculd arrive in full amount at Lee Ferry, has requirod the Engineeri~g Committee of the Upper ColoradO River Basi.n Compac.:; Conunission to ul!dertaJ:e studies and make estimations of natural conveyance losses along the Colorado, Green and San Juan rivers and certain of their tributaries above Lee Ferry, particularly in the States of Utah and New Mexico. 3. Sourceff by States o.f Stream Flow, . The Report presents no information cvnoerning the sources by State~ of the flow' of the Colorado River at Lee Ferry. Thi~ omission of data, essential to determinations of.,