WSP00456

• File Number: 8276.200
• Description: Paradox Valley Unit - Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 4
• Date: 3/20/1979
• Title: Final Environmental Statement
• Water Supply Pro - Doc Type: EIS

SUMMARY

(yeGG ,1

( ) Draft

(X) Final

Environmental Statement

Department of the Interior, Bureau of Reclamation, Upper Colorado Region

1.

Type of Action: (X) Administrative

( ) Legislative

2. Description of the proposal: The Paradox Valley Unit of the Colorado River Basin
Salinity Control Project would be located in Montrose and San Miguel Counties in
southwestern Colorado. The unit would involve pumping brine ground water from a
series of wells along the Dolores River in Paradox Valley, thus reducing the
influx of salt to the river by an estimated IBO,OOO tons annually below the pres-
ent level of 205,000 tons. The brine would be piped to a nearby hydrogen sulfide
stripping plant for the removal of toxic hydrogen sulfide gas, then piped to
Radium Evaporation Pond in Dry Creek Basin, located about 20 miles southwest of
the well field. Land would be acquired and developed as a wildlife area around
the pond to compensate for losses caused by the inundation of habitat. A 6-year
construction period would be required,

3. Summary of environmental impacts and unavoidable adverse effects: By reducing the
salinity of Colorado River water, the unit would have beneficial economic impacts
of about $4,186,000 annually for water userS in the Lower Colorado River Basin,
In the local unit area, construction would place temporary strains on community
facilities and services, but no- long-term impacts would result. Two ranchers who
own grazing land and have grazing permits on public land at the evaporation pond
would be adversely affected, one quite severely, by the necessary acquisition and
withdrawals if suitable replacement lands were not available,

The unit would reduce the average annual flows of the lower Dolores and Colorado
Rivers by about 3,950 acre'feet. The salinity of the Colorado River at Imperial
Dam would be decreased by a net value of 18.2 mgll, resulting from a decrease of
18.6 mg/l because of salt remova~ and an increase 'of 0.4 rng/l because of stream
depletion.

The existing warm water fishery in the Dolores River would be enhanced signifi-
cantly for the first 7 miles below the well field and enhanced slightly for an
additional 63 miles to the confluence with the Colorado River. A slight enhance-
ment would also occur in the Colorado River downstream from the confluence.
Wildlife habitat would be permanently reduced by 3,630 acres from inundation at
the pond and by 28 acres from the construction of other unit structures. These
losses would be largely compensated for by the acquisition and development of
3,660 acres for a wildlife area and the revegetation of about 218 acres tempo-
rarily disturbed during construction. In addition it is estimated that about 60
acres of riparian habitat along about 7 miles of the Dolores River downstream from
the well field would be ,slowly improved because of the reduction of salts in the
river water.

Two archaeological sites would be inundated by the evaporation pond. Prior to
inundation, a program to collect information would be conducted.

4. Alternatives considered:
1. One alternative evaporation pond site.
2. A lined bypass channel for the Dolores River, with an evaporation pond
adjacent to the channel.
3. Nondevelopment.
4. Five plans for smaller scales of development.

5. List of entities from whom comments have been requested or received:
See list on next page.

6.

Date made available to E.P.A. and the~ublic:
Draft statement: May 11, 1978----- ~
Final statement:

~/i.R ~ ') 1'379

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