FLOOD08553

• County: Ouray
• Community: Ouray
• Stream Name: Uncompahgre River
• Basin: Gunnison
• Title: Draft Environmental Assessment Ridgway Dam and Reservoir Water Control Manual
• Date: 4/1/1996
• Prepared For: State of Colorado
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Project

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1.4.4 Environmental Commitments. No mitigation is required if the water
control manual is adopted. Therefore, there are no environmental commitments.

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1.5 Compliance with Environmental Requirements. This draft EA has been
prepared in accordance with the National Environmental Policy Act (NEPA), Corps
Regulation 1105-2-100, and other applicable environmental statutes.

2.0 AUTHORIZATION AND PROJECT DESCRIPTION

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2.1 Authorization. Adoption of the water control manual is authorized under
Section 7 of the Flood Control Act of 1944 (58 Stat 890). The relevant portion of that
act reads as follows:

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"Hereafter it shall be the duty of the Secretary of War to prescribe regulations
for use of storage allocated for flood control or navigation at all reservoirs constructed
wholly or in part with Federal funds provided on the basis of such purposes, and the
operation of any such project shall be in accordance with. . . ."

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2.2 Project Description. Ridgway Dam and Reservoir is located on the Uncompahgre
River in Ouray County in western Colorado (see Plate 1 for area location). The project
is about 25 miles south of the town of Montrose and 15 miles north of the town of
Ouray (see Plate 2). Construction of the 230-foot-high and 2,465-foot-long earthfilled
dam was completed in 1988, Dual outlets in the dam structure assist in moderating
water temperatures and water quality for downstream aquatic life. The lower outlet is
60 feet above the streambed and has a discharge capacity of 1,397 cfs (cubic feet per
second). The upper outlet is approximately 170 feet above the streambed and has a
discharge capacity of 70 cfs. The spillway design capacity is 9,800 cfs when the pool
elevation is at 6,871.13 feet NGVD. Ridgway Reservoir has a gross pool capacity of
84,410 acre-feet of water at its normal maximum operating elevation. When full, it has
a surface area of about 1,065 acres and a shoreline of 13.2 miles.

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- Ridgway Dam and Reservoir was developed as a multipllrp9se project
authorized for flood control, irrigation, municipal and industrial water, recreation, and
fish and wildlife conservation in the Uncompahgre River Valley. The dam and
reservoir are part of the Dallas Creek Project in western Colorado. There are
additional projects in the area that also provide water for irrigation and power. A
significant portion of the land in the valley is irrigated under the Uncompahgre Project,
which was constructed by USBR and is operated by the TCWCD. Also in the vicinity
of the Dallas Creek Project are the Bostwick Park Project (which includes Silver Jack
Reservoir), and the Curecanti Unit of the Colorado River Storage Project (which
includes Blue Mesa and Morrow Point Reservoirs).

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