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4. Flows of Colorado River Table 3 on pages 22 and 23 shows the estimated virgin flow of the Colorado River at Lee Ferry, Arizona for each water year from 1896 through 1987, Column (4) of the table shows the average virgin flow for any given year within the period com- puted through water year 1987. Column (5) shows the average virgin flow for a given year within the period computed since water year 1896, Column (6) shows the average virgin flow for each progressive ten-year period beginning with the ten-year period ending on September 30, 1905. The difference between the virgin flow for a given year and the average flow over the 92-year period, 1896 through 1987, is shown in Column (7). Article III(d) of the Colorado River Compact stipulates that "the States of the Upper Division will not cause the flow of the river at Lee Ferry to be depleted below an aggregate of 75,000,000 acre-feet for any period of ten consecutiye years reckoned in a continuing progressive series beginning with the first day of October next succeeding the ratification of this Com- pact." Prior to the storage of water in the Colorado River Stor- age Project reservoirs, which began in 1962, the flow of the river at Lee Ferry in any ten consecutive years was greatly in excess of the 75,000,000 acre-feet required by the Compact. Beginning in 1962, Colorado River Storage Project reservoirs have regulated the river above Glen Canyon Dam. Table 4, on page 24, shows the historic flow at Lee Ferry for the period 1953 through 1987. The historic flow for each progressive ten- year period from 1953 through 1987, beginning with the ten-year period ending September 30, 1962, the commencement of stor- age in Colorado River Storage Project reservoirs, is shown in Column (3). In each consecutive ten-year period, the total flow equaled or exceeded the 75,000,000 acre-feet required by the Compact. The flow at Lee Ferry during the ten-year period ending Sep- tember 30, 1987 was 131,852,000 acre-feet. The charts on pages 25 and 26 illustrate some of the perti- nent historical facts related to the amounts of water produced by the Colorado River System above Lee Ferry, Arizona, the com- pact division point between the Upper and Lower Colorado River Basins. The first chart, on page 25, is entitled Colorado River Flow at Lee Ferry, Arizona. The top of each white vertical bar represents the estimated virgin flow of the river, i.e" the 21