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

one-fifth of the number and one-seventh of the weight of game fish as natural
channels (Peters and Alvord 1964). Undisturbed sections of 45 streams in Idaho
contained an average of 8 times the weight of game fish as channeled reaches
(Gebhards 1970, Irizarry 1969). Invertebrates are similarly affected in altered
stream reaches. For example, the standing crop of invertebrates was 8 times
greater in unaltered portions of the Missouri River (Morris et al. 1968).

Most streams in the Intermountain West are channelized during road and
railroad construction. For example, road and railroad construction accounted
for 66 percent of the channel alterations in 45 Idaho streams (Gebhards 1970,
Irizarry 1969) and for 51.5 percent of 403 kilometers (251 miles) of 13 streams
in r10ntana (Peters and Alvord 1964). In these studies, flood control accounted
for 19 percent of the channel alterations in Idaho and agricultural activities
including flood control accounted for 36.3 percent of the stream miles that
were altered in t~ontana. A number of studies have been made to determine the
impacts of stream channelization that are associated with highway construction
projects usually in canyon areas (Barton and Winger 1973, Elser 1968, Etnier
1972, Utah Division of Wildlife Resources 1972, Lewis 1969, Peters 1974,
Whitney and Bailey 1959, Winger 1972).

Estimates that were made by the Utah Division of Wildlife Resources
indicate that over 80 percent of prime trout habitat has been severely degraded
or eliminated in Utah. Approximately 97 kilometers (60 miles) of Class 1
streams are all that remain in Utah today. Since data are available on the
effects of stream alterations made during highway construction in canyon areas
of the West, this study was designed to detenmine the impact of stream alter-
ations on the fish and macroinvertebrates in the floodplain reaches of streams
in the Intermountain West. The specific objectives of the study were: (1) To
follow physical changes in the streambed after various types of alterations;
(2) To estimate populations and production of fish and invertebrates in altered
and unaltered reaches after different intervals of time; (3) To relate physical
and biotic changes; and (4) To provide suggestions that will minimize the
effects on fish and wildlife if alterations to the aquatic environment are
necessary.

DESCRIPTION OF AREA AND STUDY SITES

GENERAL DESCRIPTION OF THE AREA

The Blacksmith Fork and Logan Rivers in northern Utah (Figure l) were
chosen for the study since these rivers are characteristic of the rivers in the
Intermountain West. Both rivers originate as mountain streams that flow
through canyons with a steep gradient, but open into widely meandering streams
with a low gradient in the floodplain of Cache Valley. The Blacksmith Fork
and Logan Rivers have national reputations as fine trout streams and are still
important Class 1 waters in the State of Utah. In 1937, an 83 kg (37 3/4 pounds)
brown trout was taken from the lower impoundment on the Logan River. Today,
brown trout exceeding 22 kg (10 pounds) are still found in both rivers.

Cache Valley is a narrow elongate basin about 1,455 m (4,775 ft) above sea

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