WSP06068

• File Number: 8443
• Description: Narrows Unit
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1978
• Author: CO Water Resources I
• Title: The Impacts of Improving Efficiency of Irrigation Systems on Water Availability in the Lower South Platte River Basin
• Water Supply Pro - Doc Type: Report/Study

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rrig.ation sat 1!l faCt.QIJ"\I..:t: f'tlly met with no excep-
"ions throughout the tfs~ tvery year. Notice that
he same result could have been achieved with in-
reased pumping capacity.
In years when installed pumping capacity is
tmiting (to full irrigation satisfaction), improved

S(RlES I" - HISTOfllC
SERES Z" CANALS liNED
SERIES ~-. FAIl.. [F"r 7~'"
SERIES 4-- PUMP TO CAPACITY
SeRES ~-- COMBINATION

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TYPICAL l'E.lR
3"T[RLING t.o I

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IS 8 10 12 I"
IRRIGATION SEASON, W[[I(

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5 percent) farm efficiency brings the system to
(feet performance. Again, the same result could
achieved ~ith mere pumping capacity.

(~~~ ~-:_H1&.TNO:~ LNED
StRIES 3-- FARM [F"F 7~'llo
SERIES 4 -- PIMP TO CAPACITY
SERlES ~ - - COUBINATIOJ,I

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TYPICA.L YEAR
SETTLERS OITCH

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IRRIGATION SEASON, wE"EK

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18 20

CONCLUSIONS

This study indicates that capital improvements
~he irrigation system for 11n1ng of canals or

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on-farm improved efficiency arc ~ very attractive
and ....ould not solve the Lo....er South Platte basin's
....ater aupply problems in times of drought. On the
other hand, a liberal policy toward aquifer pumping
in times of drought is very attractive. The study
indicates that with 1973 installed pumping capacity
(and the right to use it) irrigated agriculture 1n
the South Platte would have ridden smoothly over the

drought of the ~O's.

If any capital money is to be

invested in the system, it appears that it should
be invested in more ~ells rather than in lining
canals.

The problem with lining the canals or increased

farm water use efficiency is that the extra water
made available to the crops for growth is proportion-
al to the amount of surface water available for

diversion in the first place. If that amount is
small, the amount of saved water is ~lso small.

These measures may be attractive to certain indivi-
dual farms but do little to incre~sc overall ~ater

use efficiency in the basin because rhe same volume
of ~ater continues to be lost do~nstream out of ~he

state.

Drawing supplemental water from the aquifer ~
needed, when and where needed, provides the best
remedy [0 ~he water supply problem. The price of

reducing water loss out of state is a modest lowering
of the water table. However, if no more land is put
into production, the system appears to reach a ne~
equilibrium State in about two years. Thus with a
pumping as needed strategy the South Platte irrigated
agriculture could weather droughts as severe as that
of the fifties and maintain its normal productivity.

The very distinct impacts of the various stra-
tegi~s show that the overall performance of the basin
water system can be controlled effectively by improved
management ~ithout much need for system physical and
capital improvements. This is not to say that indi-
vidual farm operations will not profit from such im-
provements.

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