8110

• UCREFRP Catalog Number: 8110
• Author: FLO Engineering, I.
• Title: Green River Flooded Bottomlands Investigation Ouray Wildlife Refuge and Canyonlands National Park, Utah-Final Report.
• USFW Year: 1996.
• USFW - Doc Type: Breckenridge, CO.
• Copyright Material: NO

study addresses or supports three of the five primary objectives of the conceptual framework for e
the Floodplain Habitat Restoration Program including: implementation of floodplain restoration
activities (objective 2); monitoring of basin-wide and reach-specific responses (objective 3); and
site specific (objective 4) responses to these activities. In addition, the project results will
support adaptive management practices.

Specific objectives of this study were:

· Implement a cross section monitoring program in each selected reach.
· Collect hydrographic data including cross section surveys, discharge and bed material
samples at each cross section for three flow periods: 1) at base flow prior to the rising
limb of the seasonal hydrograph; 2) near the spring runoff peak flow; and 3) at or
near base flow in the late summer-early fall.
· Calibrate the channel roughness values.
· Identify existing bankfull discharge throughout the two study reaches.
· Estimate the area of flooded bottomland inundation as a function of discharge.
· Relate the historical fl9w magnitudes, frequency and duration to the bankfull
discharge and flooded bottomland inundation.
· Recommend restoration activities and flows related to flooding bottomlands.

Site Descriptions

.

The Green River is the major tributary of the Colorado River with a basin draining
approximately 45,700 square miles of western Colorado, southwestern Wyoming and eastern
Utah. Flows in the Green River have been regulated by Flaming Gorge Reservoir since October,
1962. The major tributaries to the Green River upstream of the 9uray Site include the Yampa
and Little Snake Rivers (Figure 1). Flows in the Green River are primarily snowmelt from the
western slope of the Rocky Mountains and annually peak in late Mayor early June. The base
flow period extends from about September to March. The hydrology of the Green River has
been altered by water resource development throughout the basin. Changes which have occurred
in the magnitude and duration of discharge are discussed in the hydrology section of this report.

The investigation of flooded bottomland sites was initiated with the selection of two
L jches of the Green River: the reach in vicinity of the Ouray National Wildlife Refuge
ul~'stream of the Ouray Bridge and a reach in Canyonlands National Park in the vicinity of
Anderson Bottom-Bonita Bend. The Ouray reach was selected because of its proximity to the
razorback spawning habitat near the Jensen gage and for its potential for large areas of
floodplain inundation. Previous conceptual analysis by FLO (1994) indicated there was a strong
potential for enhancing bottomlands inundation by levee removal or construction of inlets. The
Canyonlands reach was selected for its side canyon backwater habitat which has been
successfully monitored as nursery habitat for razorback sucker larvae in recent years. The
availability of backwater habitat in this reach represents the last major concentration of .

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