9705

• UCREFRP Catalog Number: 9705
• Author: Green River Study Plan ad hoc Committee.
• Title: Study plan for the implementation and evaluation of flow and temperature recommendations for endangered fishes in the Green River downstream of Flaming Gorge Dam.
• USFW Year: 2007.
• USFW - Doc Type: Upper Colorado River Endangered Fish Recovery Program
• Copyright Material: NO

GREEN RIVER STUDY PLAN

31

February 2, 2007

base-flow variability (within-season, within-year, between years) on backwater habitat quality
(e.g., temperature, productivity) remains an uncertainty that needs to be addressed. As with
floodplain habitats, responses by nonnative fish should be considered and addressed when
managing backwater habitat formation and maintenance. Recommended studies fall into two
subject areas: (1) backwater habitat formation and (2) backwater habitat maintenance and
quality.

4: Determine the relationship of backwater habitat development to sediment
availability and peak flows in Reach 2.

Description

Understanding the relationship of habitat development to sediment availability and spring
peak flows will help to determine peak flow regimes necessary to maximize backwater habitat
development. The principal backwater nursery areas for age-O Colorado pikeminnow are in
Reaches 2 and 3; however, releases from Flaming Gorge Dam have less effect on flow and
sediment process in Reach 3. Consequently, this study should focus on integration and synthesis
of existing information on backwater topography, sediment, and physical conditions for Reach 2.

The Surface Water Modeling System (SWMS) developed and used by the USGS (Project
85F) should be evaluated to determine if this model can be used to better understand this
relationship. This synthesis should incorporate the SWMS information, USGS data on sediment
transport patterns at the Jensen gage (Project 85F), and Western's backwater topography studies.
The evaluation of existing data should be used to determine the need for additional studies
including continuation or modification of existing studies (i.e., 85t) and new studies designed to
fill information needs.

Hypotheses to Be Evaluated and Information Needs to Be FiUed

· Base flows in summer and autumn scaled to hydrologic condition favor formation of
backwaters (A8).

· Effect of peak flows, sediment availability, and antecedent conditions on relationship of
base flow and backwater availability (UI7).

· Relationship between peak flow, sediment, and habitat development (information need).

· Habitat conditions at beginning of base flow period (information need).

Implementation

· New Start.-Integration and synthesis of existing information on backwater topography,
sediment, and other physical conditions should be started in FY 2008 and completed in
FY 2009. This synthesis should incorporate SWMS findings, USGS sediment transport
data, and Western's backwater topography studies. The results of this synthesis should
be used to determine the need for additional studies.