WSP02017

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 9/1/1994
• Title: Lower Gunnison Basin Unit East Side Laterals - Colorado River Water Quality Improvement Program - SUPPLEMENT TO FEASIBILITY REPORT
• Water Supply Pro - Doc Type: Report/Study

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Chapter 2
PLAN OF DEVELOPMENT

Program Concepts

The improvement program recommended in this Supplement to the
Feasibility Report for the East Side Laterals encompasses the following
primary concepts:

. Force account construction by the Uncompahgre Valley Water Users
Association (UVWUA) of all project laterals and some small canal
segments on the east side of the Uncompahgre River under a cooperative
agreement with the Bureau of Reclamation (Reclamation). Force account
construction will involve construction management, administration, and
performance. Reclamation would provide designs and specifications
along with inspection and administrative oversite.

. Placing the laterals and small canal segments in buried pipe instead
of the originally planned (Feasibility Report/Final Environmental
Statement) thin concrete lining.

. Funding improvements through the Salinity Control Program.

. Producing benefits to the Colorado River Water Quality Improvement
Program by preventing approximately 63,880 tons of salt from entering
the river system each year at an overall cost-effectiveness value of
$70 per ton (January 1994 price level).

The salt loading reductions would be accomplished by placing project
laterals and some small canal segments on the east side of the
Uncompahgre River in buried concrete or polyvinyl chloride (PVC) pipe,
thus eliminating the majority of seepage losses from those conveyances.
Currently, seepage losses from the laterals and canals percolate through the
weathered and fractured shale of the Mancos Formation on their way to
drains and the Uncompahgre River. Salts picked up from this process
eventually enter the Colorado River system. Over the long term, this
reduction of salt loading would help maintain the numeric criteria for
downstream water quality.

Replacing the existing open earth laterals and canals with buried pipe
would produce the following potential operation and maintenance (O&M)
benefits: (1) reduced expenses for weed and brush removal, weed spraying,
repair of lateralfcanals prisms and structures, and equipment and fuel; and
(2) more efficient irrigation water deliveries with sufficient head to drive
efficient on-fann water distribution systems.