8141A

• UCREFRP Catalog Number: 8141A
• Author: Wydoski, R. S. and W. T. Helm.
• Title: Effects of Alterations to Low Gradient Reaches of Utah Streams.
• USFW Year: 1980.
• USFW - Doc Type: \
• Copyright Material: NO

line of the Logan River control site began 15 m below the Main Street bridge and
continued downstream for 92 m.

Estimation of Sand and Gravel Transport and Deposition

Cross sections measured just after dredging were compared to those measured
just after spring high flows, and areas of erosion and deposition of the stream-
bed were measured with a polar planimeter. The amount of erosion (in m2) in

two adjacent cross sections was averaged (A~B) and multiplied by the distance

between cross sections to obtain the volume of material (in m3) eroded. Depo-
sition was calculated in the same way. Summing all erosion and all deposition
values for a site yields a total volume for sediments moved, but this value
may not be comparable from one site to another because of the different lengths
of stream involved. For this reason the totals were divided by the number of
100 m intervals contained in the study reach, yielding values in m3/100 m of
stream. These values may then be compared to gain an indication of the
dynamics of a streambed. These values probably underestimate the actual amount
of erosion and deposition, especially if the time interval between surveys is
very long.

BIOLOGICAL PARAMETERS

Fish

Collections. Whitefish and brown trout populations were sampled in the
study area between February 1975 and December 1976 (Appendix B, Tables 1 & 2). Fish
were call ected with two 500 watt DC backpack el ectro-shockers. Crews of six to
fourteen people (depending on fish density, mean river width, and volume of
flow) sampled the rivers in 100 m invervals. Captured fish were held in 100 1
plastic buckets, then anesthetized in a solution (0.14 ml/l) of MS-222/Quin-
aldine mixture (Schoettger and Steucke 1970).

Fork and total lengths (to the nearest mm) were recorded for all fish
collected. Fish between 10 and 500 g and fish over 500 g were weighed on 500 g
and 5 kg capacity dietary scales, respectively. Brown trout less than 10 g
were subsampled, returned to the lab and weighed to the nearest 0.1 g on an
electric top-loading balance. Weights for whitefish less than 10 g were
estimated from a 1 ength-wei ght regression for young-of-the-year whitefi sh from
the Logan River (Brown 1972).

Fish over 50 g were marked with numbered dart tags (Dell 1968). Fish less
than 50 g were marked by removal of fins (adipose or pelVic) or by punching
holes in fins. Freeze brands (Everest and Edmundson 1967) and numbered finger-
ling dangler tags were used on occasion to obtain some information on movement
for young-of-the-year.

All fish were held until fully revived and then released in the section
where they were captured. Visual inspections of sampling areas were made at
various intervals after electrofishing to check for delayed mortality.

Movement. Movement of individual fish over 50 g could be determined during

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