9641

• UCREFRP Catalog Number: 9641
• Author: Hedrick, T. N., K. R. Bestgen and K. D. Christopherson.
• Title: Entrainment of Semi-Buoyant Beads and Razorback Sucker, Xyrauchen texanus, Larvae into Flood Plain Wetlands of the Middle Green River, Utah.
• USFW Year: 2009.
• USFW - Doc Type: C-6/RZ-ENTR,
• Copyright Material: NO

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lucius, and bony tail Gila elegans (Lenstch et al. 1996; Modde 1996; Modde and Irving 1998;

Mueller 2003).

Two main management actions initiated by the Upper Colorado River Basin Endangered

Fish Recovery Program (Program) have been responsive to the need to increase flood plain

wetland availability for early life stages of razorback sucker. The first was a program to identify

key flood plain wetlands within drainages of the Upper Colorado River Basin (Irving and

Burdick 1995). High priority areas (e.g. depression wetlands) identified were downstream of

known or suspected razorback sucker spawning areas in the middle Green River, Utah, located at

Razorback Bar (River Kilometer [RKM] 500.9) (Appendix I converts most river kilometers,

water volumes, and water velocities referenced from metric to the English equivalents), and

Escalante Spawning Bar (RKM 493.7), whose proximity to spawning bars may enhance

entrainment of drifting larvae into flood plain wetlands (Karp and Tyus 1990; Modde et al. 1996;

Muth et al. 2000, Bestgen et al. 2002, Valdez and Nelson 2004). Increased river connection and

functioning of eight high priority flood plain habitats was effected via removal or breaching of

levees in 1997 and 1998 (Birchell et al. 2002).

A second main management action to increase flood plain wetland availability for early

life stages of razorback sucker was to implement flow recommendations to enhance river-flood

plain connections in the Middle Green River (Muth et al. 2000). This was needed because spring

discharge levels of the Green River have been reduced due to impoundment and storage of flows

in Flaming Gorge Reservoir. To increase the frequency of flood plain wetland connections, the

flow recommendations implemented were designed to match spring peak and post-peak flow of

the mostly unregulated Yampa River with releases from Flaming Gorge Dam.

Recommendations sought to increase those connections mainly in average, moderately wet, or

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