8181 ‎(2)‎

• UCREFRP Catalog Number: 8181
• Author: Hamilton, S. J., R. T. Muth, B. Waddell and T. W. May.
• Title: Hazard Assessment of Selenium and Other Trace Elements in Wild Larval Razorback Sucker from the Green River, Utah.
• USFW Year: 1999.
• USFW - Doc Type: \
• Copyright Material: NO

•
CHAPTER I. INTRODUCTION
Flooded bottomlands located along the Green River have been identified as important nursery habitat
for the endangered razorback sucker and are a critical component of the Habitat Restoration Program in the
Recovery Program for the Endangered Fishes of the Upper Colorado River Basin. The goal of the Habitat
Restoration Program is to restore or enhance natural floodplain functions that support recovery of endangered
fishes in the Upper Colorado River Basin (as outlined in Final Conceptual Framework for the Habitat
Restoration Program). Some researchers believe floodplains benefit endangered fish. (Nelson, pers.comm.)
Previous investigations at Old Charlie Wash, a depression with inlet and outlet structures along Green River
near Ouray, UT, suggest that razorback larvae will passively drift into floodplain areas during overbank
flooding. Some of these larvae can survive and grow even in the presence of large numbers of non-native
fishes. (Moody, USFWS, Draft 1997)
This document presents the results of an investigation to determine the magnitude, duration and
frequency of bottomlands flooding and physical changes which might restore or enhance flooding along two
reaches of the Green River. All ten bottomland sites are located in the vicinity of Vernal, Utah. The first five
sites are referred to as the Bureau of Land Management (BLM) Sites. The BLM sites are five flooded
bottomland sites, all located on BLM lands, stretching over 22 river miles. The sites were each treated as a
separate reach for investigation purposes, but had similar characteristics. The other five bottomland sites are
all located in the Ouray National Wildlife Refuge (ONWR), and will be referred to as the ONWR sites. These
sites were initially investigated in 1995. The ONWR bottomland sites are closer together, covering 12 river
miles. The main differences between the BLM sites and ONWR sites, are that for the ONWR sites: 1) the
magnitude of floodable acreage is significantly larger, 2) structures exist for application flooding at 4 of the 5
sites, 3) the sites are on Refuge land and managed more intensively, and 4) the Ouray sites are separated
from the main channel by a combination of natural and man-made levees, whereas the BLM sites are all
• isolated by natural levees. All ten bottomland sites will serve as general models for assessing current flooding
conditions and the ability to restore channel and floodplain interaction. Inundation of the ten bottomland sites
results in flooding of 780 acres within the targetted sights at roughly a 1.5-year return period. The flooding
of these ten sites does not impact flooding at other locations within the Green River.
The project consisted of hydrographic data collection at all ten sites before and during the 1996 high
flow season, topographic mapping of the five BLM sites, collection of additional survey information at the five
ONWR sites, the application of the results of an analysis of the USGS stream gaging for the period of record
at the Green River gages at Jensen (FLO, 1996), and the design of levee removal strategies to enhance the
floodability of the ten bottomland sites. This report discusses project goals, site descriptions, river hydrology
and hydraulics, flooded bottomland hydrology, and provides recommendations and design strategies for
enhancing the floodability of the target bottomlands.
Project Goals and Objectives
The project goal was to conduct bottomland site surveys and assess the floodability at selected
historical floodplain areas in the Green River system to determine the physical changes required to
hydraulically reconnect the floodplain with the river and restore historic flood frequencies and durations. This
report addresses two objectives supported by the Recovery Implementation Program: restoring flooded
bottomland habitats and conducting inventory of flooded bottomland habitat. This report also addresses two
objectives of the Green River flooded bottomland action plan, by restoring and managing bottomland habitat
and conducting site restoration. In addition, the project results will support adaptive management practices,
and also supports the Bureau of Reclamations design and construction activities.
. Specific objectives of this study were to:
• Implement a cross section monitoring program in each selected reach.
• Collect hydrographic data including cross section surveys, discharge measurements, and