9690

• UCREFRP Catalog Number: 9690
• Author: Recovery Implementation Program
• Title: Recovery Implementation Program For Endangered Fish Species In The Upper Colorado River Basin 23rd Annual Recovery Program Researchers Meeting
• USFW Year: 2002
• USFW - Doc Type: 21
• Copyright Material: NO

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of shallow flow. Field measurements have been repeated each year (1998-2001) to coincide with
the period of peak runoff from late May through early July. In 1998, 1999 and 2000, snowpack
levels were high enough to allow some runoff to bypass the upper basin reservoirs; in 2001
snowpack levels were too low to consider using bypass flows. The effects of these flows are
similar to those described in earlier studies (Pitlick et aI., 1999; Pitlick and Cress, 2000).
Augmentation of snowmelt runoff in 1998, 1999 and 2000, produced peak discharges that
generally exceeded the threshold for gravel transport (9800 cfs); however, transport was not
widespread, especially in 1999 and 2000. Peak flows in 2001 were the lowest of the 4-year study
period, and failed to mobilize much gravel, except in localized areas. Surveys oflow-velocity side
channels and backwaters reveal minor amounts of deposition in these areas; however, substantial
amounts offines have been deposited in shallow areas along low-lying bars. Repeated monitoring
of traps placed within the bed indicates that fine sediment (silt and sand) can:fill the void spaces
between gravels in only a few days, although this depends on the specific location of the trap. The
results, taken together, suggest that coordinated reservoir operations are effective in elevating
streamflows to reach potentially important sediment-transport thresholds and maintain existing
channel characteristics. There is no reason at this time to suggest changing the recommendations
given previously.

Habitat

Nelson, P.

u.s. Fish and Wildlife Service, Upper Colorado River Endangered Fish Recovery Program Office, Lakewood, CO

Summary of Habitat Restoration Workshop - One possible scenario for razorback sucker.
Some researchers have speculated that predation by nonnative fishes on razorback sucker larvae is
a primary factor that has contributed to the decline of the species. It is unknown at this time if
efforts to control nonnative fishes will result in increases in survival and recruitment of razorback
suckers. Based on 1995-1996 results at Old Charlie Wash, it may be possible to achieve some
level of survival of razorback larvae in the presence of nonnative fishes. Assuming that nonnative
fishes will never be eliminated, levee removal evaluation study results and input from Habitat
Workshop participants have led to speculation on 'ideal' characteristics of razorback nursery
habitats and circumstances under which larval survival may be achieved.

Carpenter, M.C.1, G. R Smith2, E. J. WicI2, and 1. G. Wullschleger4

JU.S. Geological Survey, Tucson, AZ; JU.S. Fish and Wildlife Service, Denver, CO; 3Tetra Tech, Inc., Fort
Collins, CO; Wational Park Service, Fort Collins, CO

Deposition and Erosion on a Razorback Sucker Spawning Baron the Green River near
Jensen, Utah. A liquid-filled, load-cell scour sensor is being used to monitor deposition and
erosion on a sand and cobble bar on the Green River in northeastern Utah downstream from
Flaming Gorge Dam and the confluence with the Yampa River. The bar is 3 miles downstream
from the streamflow-gaging station Green River near Jensen, Utah (09261000), and is used by
razorback suckers for spawning in April and May before spring runoff. The monitoring is part of a