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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study of endangered razorback suckers being done by the U.S. Geological Survey, the National
Park Service, and the U.S. Fish and Wildlife Service under the auspices of the Upper Colorado
River Endangered Fish Recovery Program. The load-cell sensor weighs the sediment, water, and
air above it, and an accompanying pore-pressure sensor weighs the water and air above it. The
difference between the two weights is the weight of the sediment overlying the sensor pair.
Combined sensitivity and repeatability are:tO.Ol foot of sediment thickness or less. A temperature
sensor in the pressure-sensor housing provides useful information about the spawning-bed and
sensor environment and enables calibration of the pressure sensors to :to.02 percent offull-scale
output. During August 1998, seven sensor pairs were buried in an array across the bar and the
adjacent channel and have provided hourly data to a datalogger (Figure 1). The sensors
documented (1) deposition of as much as 0.7 foot of sediment on the spawning bar during the
historically determined spawning period and within the historically determined spawning-
temperature range, (2) subsequent erosion of the deposited sediment, (3) the migration of dunes
0.2 foot in height or less in the channel, (4) passage ofa cobble (or other debris) in the bed load
with a scour hole in front of and behind the cobble or debris, and (5) ice-dam buildup with
ponding of as much as 5 feet over the bar and subsequent erosion of the ice dam. During October
2001, the sensors were replaced with four pairs that were strategically located using recent data
from radio tracking offish. In addition, the cables to the datalogger were enclosed in conduit, and
the datalogger, which had been vandalized, was replaced.

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Figure 1. Streambed deposition Bnd erosion, river stage, and substrate temperature at the razorback
sucker spawning bar compared with discharge from Aaming Gorge Dam and river stage and water
temperature al the Jensen, Utah. streamftow-gaging station.

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