WSP11810

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 5/1/1975
• Title: Consumptive Uses and Losses in the Arizona Portion of the Upper Colorado River - 1973 Annual Report
• Water Supply Pro - Doc Type: Report/Study

The irrigation projects are subject to chronic water shortages, Some

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of the projects (notably Many Farms) have storage reservoirs and thus

receive a somewhat assured water supply, The remainder of the projects

are dependent on diversions from summer and fall thunderstorm flood runoff.

Thus, full potential consumptive use would be realized only in occasional

high water years.

To estimate historical irrigation consumptive use for 1973 it was as-

surned that the irrigation projects received two-thirds of the full potential

irrigation water demand. Making these adjustments, the estimated historical

irrigation consumptive use in 1973 was as follows:

Indian lands
Non-Indian lands

Potential
Consumptive Use
5,316 acre-feet
119 acre-feet

Adjustment
for Shortages
67%
67%

Historical
Consumptive Use
3,560 acre-feet
80 acre-feet
3,640 acre-feet

Account was taken of the water losses incident to irrigation (e.g.,

phreatophytes, ditch evaporation), It was assumed that such losses con-

stituted an amount equal to 10 percent of the historic irrigation consump-

tive use, For 1973, the estimated incidental losses were 360 acre-feet.

Reservoir Evaporation

A listing of all man-made reservoirs in the Arizona portion of the

Upper Colorado River Basin is shown in Table 7, Due to a lack of reser-

voir content records, it was necessary to estimate 1973 reservoir surface

a1'<eas by applying an assumed "fullness factor" against the surface area

valLIeR for a fllll reservoir.

Rl.'cords of 11lonLhly pan ('vapor3li()1l at station~, in and sUl:Tounding

the study iln'a arc found in Table' 6. Seasonal May - Oc[.obo1' pall ovapora-

ti,'r'l \\la.s adj!lsu'd to annual pan evaporation and a r(~1"1tLonshill \va.s dcvel-

P!'I\',J of :lrll1tl;ll P:111 (\v:lpornt.ion vC'rsus e10vnt Lon. Annual pan pvap()r:llil1tl