WSP04850

• File Number: 8541
• Description: San Luis Valley Project
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 2/11/1982
• Title: Draft Supplement to Final Environmental Statement
• Water Supply Pro - Doc Type: EIS

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Mum ditches, two smaller lateral canals, and one road. The ditches and canals
will pass under the conveyance channel in siphon structures, and the channel
will siphon under an existing road. The conveyance channel realinement will not
have any additional impacts.

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The channel will not be modified to improve fish habitat; however, it may be
stocked annually by the Colorado Division of Wildlife. A maximum of 10 fishing
access points may be provided.

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The conveyance channel outlet works will discharge into the Rio Grande at a
point downstream from the New Ditch diversion dam. Excavation would be about
4 feet in depth and would require the removal of about 1,500 cubic yards of
material. Excavated materials will be used to construct the conveyance channel
embankment. About 1,000 cubic yards of riprap will be used to protect the
outlet works embankment and the Rio Grande.

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The FWS is investigating the feasibility of establishing artificial raptor
nesting platforms as an enhancement feature. No nesting platforms were included
in the 1979 FES.

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Public Service Company of Colorado and the San Luis Valley Rural Electric
Cooperative, Inc. will provide the transmission facilities to deliver electric
power to the project area. The estimated 13 million kilowatt-hours of electri-
city a year required for the project will be obtained from electric companies
in the San Luis Valley. The 1979 FES estimated that overhead lines would total
44 miles and underground lines would total 96 miles. It is now believed that
overhead lines will total more than 44 miles and underground lines will total
less than 96 miles with the revised plan. The main line will not be buried.
No appreciable change in impacts over those shown in the 1979 FES are
anticipated.

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A monitoring system has been established in Stage 1-2 to provide positive
identification of any fluctuation in the water table outside the project boun-
dary. Expansion of the system will continue with respect to any remaining
stages to be developed. At the time the 1979 FES was prepared, there were '18
observation wells being monitored; there are now more than 300. Production
well pumping rates can be adjusted so that the hydrologic balance of the ground
waters, within and outside the project area, will not be adversely affected.

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Periodic readings will be taken at 1- to 3-month intervals on more than 300
observation wells in and around the project by the U.S. Geological Survey
(USGS), Rio Grande Water Conservancy District (RGWCD), and the Bureau. In
Stage 1-2, about 37 of these wells are permanent observation wells. These
readings will be taken for positive identification of the water table in and
outside the 130,000-acre project boundary. The identification will assure
that the drawdown will not exceed 2 feet outside the project boundary. Records
of these measurements will be available to the public.

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A total of 1,107 acre-feet of artesian water rights would annually be required
for mitigation of project effects. The points of use of the acquired water
rights would be transferred to the Alamosa NWR and Blanca WHA. About 800 acre-
feet of these water rights would be transferred to Alamosa NWR and 307 acre-feet

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