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

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

Supplemental Users

Supplemental water users are irrigators that have two sources of water supplies: I)
surface waters from ditches or similar diversions with surface water rights; and 2) pump
irrigation that supplements surface supplies. Supplemental users have 321 wells pumping
an average of 146 afper well (Helton and Williamsen, P.C.). Helton and Williamsen,
P.C. have estimated that total pumping during a normal year is 49,966 af. Using the
depletion factor of 0.3, this amounts to 14,990 af of depletion. As described earlier, only
about 60-63% of depletion must be replaced. Thus, supplemental users have a demand
for 14,090 afofreplacementwater (see Table 1).

During dry years, supplemental users would increase pumping to offset decreased surface
water availability. Unconstrained pumping levels could increase to as high as 74,949 af
with a demand for 14,097 af of replacement water (74,949 x .3 x .627).

Sole-Source Users

Sole-source flood and sprinkler irrigators use groundwater as the only available supply of
irrigation water. Sole-source users have 86 wells pumping an average of 238 af per well.
Total pumping for this group during a normal year is 23,299 af, with 10,199 afpumped
by sole-source flood water users and 13,100 af pumped by sole-source sprinkler water
users (Helton and Williamsen, P.C.). Using the depletion factor of 0.5 and 0.75 for sole-
source flood and sprinkler water users, respectively, this amounts to a total of 14,925 af
of depletion for the two groups (5,100 af for sole-source flood and 9,825 af for sole-
source sprinkler water users). Total replacement for these two groups is 8,890 af, (3,068
affor sole-source flood and 5,912 affor sole-source sprinkler).

Both groups of sole-source users have some increase in water use during a dry year, but
the increase is small relative to supplemental users. Unconstrained pumping for sole-
source use increases to 11,219 af for sole-source flood and 14,410 for sole-source
sprinkler resulting in 3,515 af and 6,773 af of replacement water for the two groups.

Tributary Users

Tributary users are groundwater users off the mainstem of the Arkansas River. Pumping
by these users has a relatively small effect on the river or the need for replacement water.
The irrigators pump 3,000 afper year. Depletion and replacement are respectively
estimated at 120 and 89 afper year.

Other Users
Other members of LA WMA include commercial and municipal groundwater users.
These entities already have individual surface water rights that offset their pumping
depletions. The commercial and municipal users are important sources of revenue to
LA WMA, contributing $26,000 per year.

~.

EnWater Resource Consultants September 5, 1997 Final Report

17