WSP07117

• File Number: 8276.130
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 11/1/1990
• Title: Final Environmental Assessment: Price and Stubb Ditch Improvements - Grand Valley Unit
• Water Supply Pro - Doc Type: EIS

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CHAPTER I
INTRODUCTION

General Description and Purpose of Assessment

This Environmental Assessment (EA) for changes in the Grand Valley Unit
(Unit) of the Colorado River Basin Salinity Control Project, is prepared in
compliance with the National Environmental Policy Act (NEPA) of 1969
(Public Law 91-190) and under current guidelines established by the Council
on Environmental Quality, the u.s. Department of the Interior, and the
Bureau of Reclamation (Reclamation). The purpose of the EA is to evaluate
environmental impacts that could occur with the improvement of two
irrigation conveyances, the Price and Stubb Ditches within Stage Two of the
Grand Valley Unit and with changes in cross-drainage plans for previously
approved portions of the Unit. This assessment is also intended to serve
environmental review requirements in compliance with Executive Order 11988,
Floodplain Management, and Executive Order 11190, Protection of Wetlands.

Grand Valley Unit Final Environmental Impact Statement

A Final Environmental Impact Statement (FEIS) on the Unit was completed in
May 1986, however, the improvement of the Price and Stubb Ditches was not
included. This EA is prepared to show the incremental impacts of improving
these ditches and deleting cross-drainage facilities on the East End
Government Highline Canal.

In planning studies for the Unit, Reclamation analyzed the cost
effectiveness of lining the canal systems within the Unit area. Initial
estimates of seepage and corresponding salt loading indicated that it was
not cost effective to line the Price and Stubb Ditches although the
laterals served by the ditches were cost effective and were included in the
FEIS. Consequently, the Price and stubb Ditches were eliminated from
further consideration in the early planning phase of the project. They
were not included in the alternatives analyzed in detail in the FEIS nor
among the components of the recommended plan described in the Supplement to
the Definite Plan Report. A Verification Memorandum (VM) was prepared in
May 1986 to reaffirm the viability of the plan of development. Refined and
more detailed seepage and salt loading estimates developed for the VM
indicated that the salt loading attributed to portions of the private
irrigation canals and ditches was significantly higher than originally
estimated.

Later, after the FEIS had been filed and the VM completed, the refined salt
loading and new cost estimates were applied to some of the increments which
had previously been eliminated. The cost effectiveness of lining the Price
and Stubb Ditches was found to be more favorable. (Cost effectiveness data
is shown in chapter 2.) Consequently, Reclamation is proposing to include
the improvement of these two ditches as part of the Unit.

Location

The Unit is located along the Colorado River in western Mesa County in
west-central Colorado. For the most part, the Unit includes that portion
of the Grand Valley consisting of approximately 70,000 acres of land
irrigated by both Federal and private systems, as shown on the Frontispiece
Map. The city of Grand Junction, located at the confluence of the Colorado
and Gunnison Rivers in the central part of the valley, is the largest

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