LPPD000265

• Contract/PO #: C153756
• Contractor Name: Lower Arkansas Water Management Association
• Contract Type: Loan
• Water District: 67
• County: Prowers
• Bill Number: SB 96-124
• Loan Projects - Doc Type: Feasibility Study

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Table 1: Pmnpin2, Del)letion and Replacement lDuler noulla! and dry years (acre-feet)
Sole- Sole-
Tributary Suoolemernal Fl ood Sprinkler TOTALS
Nonnal Year pt.nqling 4,116 49,966 10,199 13,100 77,381
x Depletion factor 0.02 0.3 0.5 0.75
Total Depletion 82 14,990 5,100 9,825 29,997
x Rfplacenutfactor 0.602 0.602 0.602 0.602
Total Replacerrm 50 9,019 3,068 5,912 18,049

Dry Year plUJ1)ing 4,528 74,949 11,219 14,410 105,106
x Depletion Factor 0.02 0.3 0.5 0.75
Total Depletion 91 22,485 5,610 10,808 38,992
x Replacement factor 0.627 0.627 0.627 0.627
Total Replacement 57 14,090 3,515 6,773 24,435

compensate for decreased surface water supplies available through ditches. The
amOlmt of depletion and replacement also increase proportionally. Because the
amolUlt of required replacement water is directly related to the desired (demand) for
pumping, we call this requirement the demand for replacement water.

An example would be a sole-source flood irrigator pumping 200 af of water. The
amOlmt of depletion for this irrigator is 100 af(200 afx 0.5 - depletion factor).
The amount of replacement water LA WMA must obtain to mitigate the impact of
this irrigator is 62.7 af (200 x 0.5 x 0.627). This amolUlt is a sole-source flood
irrigator's demand for replacement water. What LA WMA can supply to this and
all other users depends on river conditions.

Replacement demand is the amolUlt of replacement water needed to offset pumping if
there were no restrictions on pumping. An example follows: Suppose a supplemental
irrigator pumps 200 af of water during a normal year. His depletion of groundwater is
estimated at 60 af (200 afx 0.3). The amoilllt of replacement water needed to offset this
pumping, replacement demand, is 36.12 af(60 x 0.602).

Replacement Water Pool

LA WMA has acquired surface water rights to offset impairment by member prunping.
These water rights have priority dates that determine the quantity of water that can be
used in any year. Based on analysis conducted by Helton & WilIiamsen, P. C. the current
water rights held by LA WMA have an average yield of22,160 af. This includes 5,119 af
of Article II AccOlmt water that can be held in JMR for approximately one year.

EnWater Resource Consultants September 5, 1997 Final Report

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