WSP04999

• File Number: 8054
• Description: Water Salvage
• State: CO
• Basin: Statewide
• Date: 6/1/1975
• Author: Utah Water Research
• Title: Water Salvage Potentials in Utah - Volume II - Evaporation Suppression by Reservoir Destratification
• Water Supply Pro - Doc Type: Report/Study

Table 14. Evaporation and suppression summary for the south and east Colorado Basin.

Surface Area Lake Evaporation POlential
Basin Number 9 Max Mean Annual Seasonal Savings
Reservoir Type (acres) (ac ft) (ac ft)
5 Manmade lake over 1000 ac 162700 114000 650433 487825 152264
6 Manmade lake 100 to 1000 ac 728 582 1231 923 0
7 Manmade lake under 100 ac 0 0 0 0 0
Totals 163428 ll4S82 651665 488748 152264
Percent of state totals 29.9 26.1 38.3 36.8 77.6
(Fresh water only)

Table 15. Evaporation and .nppresslon summary for the Lower Colorado Basin.

Surface Area lake Evaporation Potential
Basin Number 10 Max Mean Annual Seasonal Savings
Reservoir Type (acres) (ac ft) (ac ft)
5 Manmade lake over 1000 ac 0 0 0 0 0
6 Manmade lake 100 to 1000 ac 1790 1381 3643 2757 276
7 Manmade lake under 100 ac 0 0 0 0 0
Totals 1790 1381 3643 2757 276
Percent of state totals 0.3 0.3 0.2 0.2 0.1
(Fresh water only)

Economic FeaslbUlty

The best source of c(,~t information on
reservoir destratification is contained in an A WW A
committee report (Symons, 1971). This paper
summarizes the results of a survey of water
suppliers who have used artificial destratification
for water quality reasons. The report includes three
figures showing energy capacity requirements,
capital investment costs, and operating and
maintenance costs. each as a function 01 reservoir
volume. The figures include data from 24 reservoirs
upon which various air and water pumping systems
were used. The cost/volume regression plots
include considerable variability but both (especially
O&M) figures show substantial economies of scale.
By com bining the best fit lines for both fixed and
variable cost figures from the Symons report a least
squares total cost function was derived as follows:

C, = 65.5324.-.60"96 Ln (Vol)

in which C1 is the annual cost in dollars per acre
foot of reservoir storage and Vol is the reservoir
storage. This function is shown as total cost in
Figure 18 along with the O&M cost function. The
Symons capital investment function (the difference

between the two lines shown in Figure 18) was
converted to an annual cost basis by assuming a 15
year life of major equipment and 7 percent interest.
The Symons cost data were reported during 1970.
Both capital investment and operating costs have
increased since then, but no inflation factor was
included in the costs reported herein.

In order to determine cost as a function of
water salvaged the following relationship was used:

C, = CtlVol)/fl.Vol

in which C, is the annual cost in dollars per acre
foot of water salvaged and fl.Vol is the volume of
waler salvaged. These cost functions were applied
to the suppression mode' results for Utah
reservoirs. The resulting unit costs are included in
Appendix I. The form of the C, function results in
high unit costs on reservoirs which have low
suppression potentials. In order to eliminate most
of the obviously infeasible costs, reservoirs with less
than 4 percent su ppression rates were deleted from
the cost computation. Those reservoirs with salvage
costs below $40 per acre foot are listed and
summarized in Table 16.

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