9568

• UCREFRP Catalog Number: 9568
• Author: Resource Consultants Inc.
• Title: Sediment Transport Studies of the Little Snake, Yampa, and Green River Systems.
• USFW Year: 1991.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

SEDIMENT TRANSPORT STUDIES OF TIlE UTILE SNAKE,
YAMPA, AND GREEN RIVER SYSTEMS

INTRODUCTION

1.1 Study O~jectives

The objective of this study was to establish baseline hydrologic and sediment transport information
on the Uttle Snake, Yampa, and Green River systems. These river systems are part of the upper Colorado
River basin and are an integral part of the Recovery Implementation Program for Endangered FISh Species
(USFWS, 1987). One concern of the Recovery Program is the potential for adverse modification of
threatened and endangered fish habitat as a result of morphological changes. Various rare fish species
utilize different river channel habitats during their respective life stages; two habitats focused on to date
include spawning and backwater areas. Both of these habitat areas are known to exist in the Yampa and
Green Rivers. Morphological changes that could adversely impact these habitats include:

Significant reductions in transport capacity of the mainstem Yampa River may result in
sedimentation of the cobble spawning bars, or sedimentation of the pool/riffle habitat. Clean
cobble substrate may be required for successful spawning.

Significant reductions in transport capacity of the Green River may allow aggradation in backwater
areas resulting in the loss of backwater habitat through merging of islands and bars with stream
banks.

Significant reductions in sediment supply to the Green River may allow channel degradation and
narrowing, with concurrent alteration of backwater habitats.

In order to understand and predict potential morphological response resulting from both natural
and man-induced changes, it is important to first understand existing conditions and river response
mechanisms. This report relies on previous research efforts, supplemented by additional field and
analytical investigations, in an effort to consolidate and establish important baseline information related to
hydrology and sediment transport processes in the Uttle Snake, Yampa, and Green River systems.

1.2 Drainage Areas and Existin~ Water Development Pr~ects

The Green River is a major tributary of the Colorado River with a drainage area of 44,700 square
miles (Fig. 1.1). The Yampa River is a major tributary to the Green River with a drainage area of about
8,000 square miles in northwestern Colorado and south central Wyoming (Fig. 1.2). The Little Snake
River is a major tributary to the Yampa with a watershed area of about 3,730 square miles, joining the
Yampa River at Deerlodge Park.

The Green River originates in southwestern Wyoming and is controlled by two mainstem
reservoirs, Fontenelle and Flaming Gorge. Flaming Gorge is located 410 miles upstream of the Colorado
River confluence and was completed in 1962. Fontenelle Reservoir is about 150 miles upstream of Flaming
Gorge and was completed in 1964.

1-1