PROJC01741 ‎(3)‎

• Contract/PO #: C153768
• Contractor Name: Lower Arkansas Water Management Association
• Contract Type: Loan
• Water District: 67
• County: Bent
• County: Prowers
• Bill Number: SB 96-124
• Loan Projects - Doc Type: Feasibility Study

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sprinklers, respectively. Currently, LAWMA's irrigation members in the mainstem area include
270 supplemental wells, 137 sole-source wells, and 36 wells which are a combination.

Tributary Areas. LAWMA covers the 46 irrigation wells and the 17 municipal wells (Eads, Kit
Carson, and Hugo) in the tributary areas, primarily the Big Sandy and Two Butte Creeks basins.
Depletions caused by these wells must be replaced with respect to calls from Colorado ditches.
Two Butte Creek joins the Arkansas River at Holly, downstream of any Colorado ditch. The
confluence of Big Sandy Creek and the Arkansas River is located about 8.5 miles upstream
from the Buffalo Canal diversion. Big Sandy Creek normally is intermittent except during major
precipitation events. The stream flow during these events is reduced by the amount of
recharge induced by the wells. Otherwise, the pumping affects evapotranspiration (ET) by
native vegetation in the creek valley. The depletions with respect to the Arkansas River were
estimated to be equal to 4 percent of the wellhead depletions on an annual basis (1996, Helton
and 1997, Helton). The pumpage from the tributary areas totaled 4,116 acre-feet in 1996,
representing 165 acre-feet of potential depletions. The 1996 pumpage volume is a good
estimate of future pumpage in the tributaries by LAWMA's present membership.

Mainstem Municipal Wells. The City of Lamar has a well field in the Clay Creek basin. The
City conveys water obtained from SECWCD through the Fort Bent Canal to a recharge site on
Clay Creek. Such deliveries are fully consumable and sufficient to replace the City's depletions.
The Lamar Light & Power wells are used to cool the generation equipment at the Lamar
Powerplant. Depletions are not charged to these wells as the cooling system is fully contained
and the heated water is discharged to the Lamar Canal and charged against the Lamar Canal
decrees. The municipal wells used by the May Valley Water Association, Town of Wiley, Town
of Granada, Town of Holly, Hasty Water Company, and McClave Water Association derive their
supplies from the Dakota and Cheyenne aquifers and are not subject to the use rules. The
Granada School District, the Lamar Community College, and Prowers County Courthouse are
considered municipal members, but their wells are used strictly for irrigation purposes and their
pumpage is included with the irrigation pumpage estimates.

Mainstem Irriaation. The irrigation well pumpage is summarized in Table 1 for 1986 through
1996. The values for 1995 through 1997 were compiled by the Division Engineer from power
and flow meter records. For this period, the irrigation pumpage in the mainstem averaged
61,180 acre-feet annually and ranged from 22,575 acre-feet in 1987 to 88,892 acre-feet in
1991. For planning purposes, mainstem pumpage should average about 67,500 acre-feet
annually and should total about 100,000 acre-feet in a dry year.

Stream Depletions. The depletions for each river segment described above were estimated
using the accounting model and the above-described pumping levels. The depletions are

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