8065

• UCREFRP Catalog Number: 8065
• Author: Vaill, J. E.
• Title: Computation of Selected Hydraulic Variables for the Lower Yampa River in Northwestern Colorado.
• USFW Year: 1997.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

Computation of Selected Hydraulic Variables for
the Lower Vampa River in Northwestern Colorado

By J.E. Vaill

Abstract

Computation of selected hydraulic
variables was done for three reaches on the
lower Yampa River that were identified as having
natural or manmade barriers that might impede
the migration of endangered Colorado squawfish.
The three reaches included the Patrick Sweeney
and the Maybell Canal diversion structures and
Cross Mountain Canyon. Minimum stream depths
and maximum stream velocities for a range of
streamflows were computed using the Water-
Surface PROfile computation program for cross
sections in each of the three reaches. Cross-
section information used as input to the computa-
tion program was determined from field surveys
or from existing detailed topographic information.
Output options in the program were used to
generate tables of hydraulic variables for stream-
flows ranging from 50 to 400 cubic feet per
second, including minimum depths and maximum
velocities for 20 stream tubes in each of the cross
sections selected for study.

INTRODUCTION

The Colorado squawfish has been identified
as an endangered species (U.S. Fish and Wildlife
Service, 1996) that inhabits the lower Yampa River
from the mouth at the Green River upstream to
near Juniper Hot Springs (fig. 1). The Colorado
squaw fish overwinters upstream from Maybell
and migrates annually downstream to spawn in the
part of the Yampa River located in Dinosaur National
Monument. Depending on the water temperature of

the river, the fish migrate in late-May to mid-June.
The upstream return migration is in mid- to late-July
after spawning is complete. During some years,
streamflow in the Yampa River is very low as a result
of low snowpack, early snowmelt runoff, minimal
precipitation, and depletions by upstream water users.
For example, in August 1994, a streamflow of less
than 5 ft3ts was measured in the Yampa River near
Maybell. During periods of such low streamflow,
irrigation structures and some stream reaches on the
Yampa River may become barriers to the upstream
return migration of Colorado squawfish (Hydrosphere
Research Consultants, 1995).
The U.S. Geological Survey (USGS), in cooper-
ation with the Colorado River Water Conservation
District (CRWCD), began a study in 1996 to evaluate
the hydraulic variables of minimum depth and
maximum velocity for a range of streamflows at cross
sections in three reaches of the lower Yampa River
that have been identified as possible barriers to fish
migration. A previous assessment of 119 potential
barriers to migrating fish in the lower Yampa River
indicated that the manmade structures most likely to
impede migration of the Colorado squawfish during
low-flow conditions were the Patrick Sweeney
diversion structure downstream from Government
Bridge and the Maybell Canal diversion structure in
Juniper Canyon (Hydrosphere Research Consultants,
1995). An unresolved issue in that assessment was
whether or not Cross Mountain Canyon (fig. 1)
is a critical natural barrier to squawfish migration
(Hydrosphere Research Consultants, 1995).
Cross-section geometry was obtained from
field surveys or from available detailed topographic
information for the diversion structures provided by
CRWCD. Stream-channel geometry data were input
to the Water-Surface PROfile (WSPRO) computation

Abstract 1