9560

• UCREFRP Catalog Number: 9560
• Author: Valdez, R. A.
• Title: A Generalized Interactive Model to Predict Floodplain Habitat Area Needed to Recover the Endangered Razorback Sucker in the Upper Colorado River Basin - Floodplain Model Version 5.1.
• USFW Year: 2004.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

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EXECUTIVE SUMMARY

Background
The Habitat Restoration Program of the Upper Colorado River Endangered Fish
Recovery Program (Recovery Program) is identifYing, acquiring, and enhancing floodplain
habitats in the Upper Colorado River Basin to assist with conservation and recovery of the
endangered razorback sucker (Xyrauchen texanus). Adults spawn during runoff on cobble and
gravel riffles in the main river and newly-hatched larvae drift into riverside floodplains that serve
as nurseries and rearing habitats. The amount of floodplain habitat necessary for recovery of this
endangered species is unknown. The goal of this project was to determine the approximate area
of floodplain habitat necessary to recover the endangered razorback sucker in the Upper
Colorado River Basin.
Floodplain Area Available
Reconnaissance showed that there were 132 sites with 18,430 potential acres of
floodplain habitat along the Green River in 1993; 110 sites with 12,315 acres along the Upper
Colorado River; and 48 sites with 3;227 acres along the Gunnison River. High water flow of
18,200 cfs in May 1993 inundated 74 sites and 7,720 acres along the Green River, including
6,093 acres from Pariette Draw to Dinosaur National Monument (RM 238-320), the reach
occupied by the only remaining wild population of razorback sucker in the upper basin.
Examination of aerial photographs determined potential bottomlands for the same reach of 5,904
acres at 20,000 cfs; 9,550 acres at 22,000 cfs; and 13,927 acres at 25,000 cfs. Average peak. flow
of the Green River near Jensen for 56 years of record through 2000 is 19,706 cfs, indicating a
potential. of about 6,000 acres of floodplain habitat.
Model Overview
A computer model called FLOODPLAIN (Version 5.1) was developed on an Excel
worksheet platform. The Excel file includes five worksheets ("Model", "Drift", "SiteSurvey",
"Sensitivity", and "DataSources") and seven charts that illustrate data used for internal model
computations. The worksheet "Model" contains FLOODPLAIN. The model is user interactive
and consists of31 numbered steps, includIng 21 user-specified input variables and 50 automated
output variables. Input variables are the most important, but often lesser known, aspects of the

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