WSP00380

• File Number: 8149.100
• Description: Miscellaneous Small Projects-Project Studies - NRCS-Ft Lyon Canal Co-Limestone-Graveyard Creeks
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 9/1/1992
• Author: US Dept of Agricultu
• Title: Lower Arkansas River Basin - Water Quality Study - Colorado
• Water Supply Pro - Doc Type: Report/Study

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002535

2

I. SUMMARY

The initial objective of this study was to identify
potential water quality project areas that could be
implemented to produce a positive affect on salinity levels
in the Arkansas River.

A canal system model and a river model were developed for
purposes of making water quality evaluations. sixteen canal
systems were studied for possible project implementation.
The nature of the proposed projects would be to implement
on-farm practices, such as irrigation water management, land
leveling, ditch lining, water control structures, etc. It
was estimated that these improvements would raise the on-
farm irrigation efficiency by 15 percent (40 to 55 percent).

These potential projects were evaluated as single projects
(one canal system) and combinations of projects. The on-
farm effects generally include an increase in crop
consumptive use and a reduction in return flows and
groundwater recharge. It was determined that the effects on
water quality in the Arkansas River would be minor. For
example, with projects implemented on all canal systems the
total dissolved solids (TDS) was estimated to be 2511.3 mg/l
at the Colorado-Kansas state line compared to 2509.22 mg/l
without the projects. This is typical of data at other
locations along the river.

It appears that the most significant positive effects of
these projects would be local benefits of increased crop
production due to greater water availability and possibly
reduced irrigation pumping costs, both a result of improved
irrigation efficiencies. Operation and maintenance (O&M)
and labor costs would be reduced significantly.

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For example, there appears to be a shortage of water to meet
crop consumptive use in the Holbrook Canal of 15,468 AF in
the without project conditions. If the on-farm irrigation
efficiency could be improved by 15 percent, this shortage
would be reduced to 8,338 AF, or a reduction of 46 percent.
Water users under the Fort Lyons Canal pump about 27,304 AF
of irrigation water in the without project condition. with
the pumpage, there still remains a consumptive use shortage
of 34,030 AF. with project conditions, there would be no
shortage and 17,081 AF less pumpage would be needed.

The two models used in this study are available for more
site specific investigations on other studies of this
nature.