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<br />
<br />TABLE 1
<br />NATURAL FLOW AT LEE FERRY
<br />
<br />Water Year
<br />
<br />Natural Flow
<br />
<br />1973
<br />1974
<br />1975
<br />1976
<br />1977
<br />1978
<br />1979
<br />1980
<br />1981
<br />1982
<br />1983
<br />1984
<br />1985
<br />1986
<br />1987
<br />1988
<br />1989
<br />1990
<br />1991
<br />
<br />19,435,000
<br />13,307,000
<br />16,150,000
<br />10,723,000
<br />5,023,000
<br />14,660,000
<br />17,337,000
<br />16,935,000
<br />7,413,000
<br />16 108,000
<br />at;647,000---:,
<br />23,511,000
<br />20,163,000
<br />21,883,000
<br />16,924,000
<br />11,581,000
<br />9,107,000
<br />8,662,000
<br />11,399,000
<br />
<br />
<br />NOTE: 1986-91 are preliminary, subject to revis'
<br />
<br />The natural flow for 1977 t Lee Ferry of 5.023 million acre-
<br />feet (maf) was the dries~y~~n record for the period 1906-1991,
<br />and 1983, with a flow of~ maf, was the wettest. The period
<br />1983 through 1986 was a period of significantly above-normal
<br />runoff. Each of those four years had a natural flow in excess of
<br />20 maf, with a four year average of 22.3 maf. Only once before, in
<br />1920 and 1921 did 20 maf of natural flow occur for two or more
<br />consecutive years and only other period (1920-1923) had an average
<br />natural flow exceeding 20 maf (20.4 maf). From 1988 through the
<br />1991 water YearS~flOWSJ have been well below normal.
<br />
<br />Preliminary d a indicates that natural flow at Lee Ferry for
<br />water year 1991' bout 75 percent of normal. The long-term mean
<br />natural flow for he period 1906-1991 is 15,114,000 acre-feet.
<br />
<br />STORAGE CHANGES
<br />
<br />Upper and Lower Basin reservoir storage increased from 1972
<br />through 1983, and began declining in 1987. By 1992, the storage
<br />had declined sharply. As shown on Figure 1, basinwide storage at
<br />the end of Calendar Year 1991 was about 12.6 maf less than at the
<br />end of 1987. Of the total difference, 7.6 maf was in the Upper
<br />Basin and 5.0 maf was in the Lower Basin. The 1991 end of calendar
<br />year storage in the Colorado River system was about 1,502,000 acre-
<br />feet less than the 1990 value.
<br />
<br />2
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