WSP03260

• File Number: 8276.120.10
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 9/10/1991
• Title: Final Environmental Assessment: Alternative Lining Methods for the Government Highline Canal - Grand Valley Unit
• Water Supply Pro - Doc Type: EIS

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The removal of encroaching structures to allow for construction of
the canal is costly to the project. The practice of using the
canal lands in farming operations increases canal O&M costs in
favor of financial gain to private users. under all alternatives,
including the No-Action Alternative, Reclamation plans to eliminate
unauthorized uses by fencing the u.S. fee land boundary and working
with the GVWUA to prevent such future use. Elimination of private
use of the corridor for agricultural production would reduce crop
production where the farmer must utilize his own property; the
extent of this loss is unknown.

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In the Associated Actions section of the Description of
Alternatives chapter, the procedures to be used to apply for a
right to use the canal corridor is discussed. This process is
always available to any applicant for a variety of uses, and
approval is generally granted to uses that would not interfere with
the purpose for which the property is held by Reclamation. Under
the salinity project, this process for access permits would be
facilitated by waiving application fees as described.

while seepage reduction is primarily designed to improve Colorado
River quality, the reduction would also benefit farmers downhill of
the canal by reducing seepage into fields and lowering the water
table in poorly drained areas during the irrigation season.
Although unquantified, this benefit is expected to increase crop
production, provide more flexibility in crop selection, and reduce
structural problems of adjacent residences which might be
aggravated by a high water table.

Summarv of Imoacts

Overall the environmental impacts of design changes since the FEIS
center on land use and safety considerations. Concrete-lining
alternatives would place a significant new safety hazard in the
area, while membrane-lining would reduce safety hazards. This is
an important consideration as the area has a relatively high
population density even though it is agricultural. Permanent land
use impacts to adjacent landowners, on the other hand, are greater
with membrane-lining alternatives HI and M3. For example, Modified
Alternative Ml would permanently utilize a maximum of 5.1 acres of
permanent crops along Reach lA, while Alternatives M4 and Cl would
not require any. All alternatives would involve fencing of the
u.s. land for safety and O&M reasons, and is expected to reduce
problems associated with unauthorized uses of land such as
encroachments, vandalism, and disruptive use by a minority of the
public. Existing private uses of the canal lands for access are
protected as described previously. The concrete lining would more
likely restrict future recreation use of the canal, while membrane
lining would be compatible with any future plans for this use.

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