WSP06604

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/28/1989
• Title: Graphical comparison of the data contained in the BOR's Draft Colorado River System Consumptive Uses and Losses Report-- 1980-1985-- Part 1 of 2
• Water Supply Pro - Doc Type: Report/Study

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Large deviations from trend should be
examined carefully to determine
whether a reasonable explanation might
justify its existence. Examples of
these are the charts on Graph UB-5
which represent consumptive uses by
agricultural irrigation for various
regions in the upper basin (see Figure
2). In all charts, the values for
1977 are substantially lower than for
other years. An explanation for this
may be the drought conditions that
existed in 1977 (ie. the virgin flow
for 1977 was only 5.8 million acre-
feet, one of the driest years on
record). Therefore, the trend of
these values on these charts seems to
be reasonable or at least explainable.

Some patterns are much more difficult
to explain. Consider for example,
Graph UB-7 and the chart on stockpond
evaporation in the San Juan Basin in
Arizona (Figure 3). For the first 10
years (first two Uses and Losses
Reports) , the consumpti ve uses
averaged about 1,000 acre-feet per
year. In the last five years (current
Uses and. Losses Reports), the
consumptive uses jumped to 3,500 acre-
feet. It is possible that much better
information became available during
preparation of the last consumptive
Uses' and Losses Report, but such
deviations should be examined
critically.

AGRICULTURAL - IRRIGATION
UTAH - Upper Main

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71 72 73 74 76 76 77 78 79 80 81 82 as 84 86
Water Year

Figure 2

AGRICULTURAL - STOCKPOND EVAPORATION
ARIZONA - San Juan

(1,000 Acre-Feet)
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71 72 73 74 715 76 n 78 79 80 81 82 8S 8<4 86
....Vater Yeai

Figure 3

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