8059

• UCREFRP Catalog Number: 8059
• Author: Burdick, B. D. and F. K. Pfeifer.
• Title: Discussion Of The Merits For Fish Passage At Hartland Diversion Dam On The Gunnison River Near Delta, Colorado-Final Report.
• USFW Year: 1996.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

common found downstream of Hartland include green sunfish (Lepomis c anellus and black
bullhead (Ameiurus means). Although northern pike (Esox Lucius) occupy the Gunnison River
both up- and downstream of Hartland, their numbers are low and they do not appear to be
reproducing in the Gunnison River. Juvenile and adult white sucker (C. commersoni) are
prevalent in reaches both up- and downstream of Hartland.
The composition and relative abundance of smaller-sized fishes upstream of Hartland
Diversion are unknown. Upstream of Hartland, sampling with gear designed to collect small
fishes has been extremely limited. Both fathead minnow (Personal communication, Richard
Krueger) and green sunfish (Personal communication, Sherman Hebein) have been collected in
the Gunnison River upstream of the diversion dam. Sand shiner and black bullhead have not be
collected in the mainstem Gunnison River upstream of the diversion. However, it seems
reasonable that black bullhead would also occur in the Gunnison River upstream of the diversion
dam because they have been collected in off-stream ponds and irrigation returns that drain into
the Gunnison River upstream of Hartland. Because habitat up- and downstream of the dam is
similar, fish composition is also assumed to be similar.
Blockage By Dams
Fish Passage
Blockage of movement by dams and water diversion structures has been suggested as an
important cause for the decline of the Colorado squawfish and razorback sucker in the Upper
Colorado River Basin (Tyus 1984; Burdick and Kaeding 1990). Although the actual role of
blockage to the decline of razorback sucker in the upper basin is unknown, providing fish passage
past instream barriers has come to be considered an important means to aid the recovery of this
species. Hartland Diversion Dam apparently impacts the upstream range and movement of
another native fish, the roundtail chub. The numbers of adult roundtail chub captured in both
1992 and 1993 immediately upstream of the diversion dam were significantly lower (a magnitude
of about five times) than those downstream of the structure (Burdick 1995).
Providing access upstream of Hartland Diversion is part of planned razorback sucker
chemoreception and imprinting field studies, and critical to providing access to approximately 7
miles of off-channel bottomland habitats available along the Gunnison River. Twenty pond-
reared adult razorback sucker implanted with long-term (4+ year) radio transmitters were stocked
in the Gunnison River near Delta in the spring of 1994. An additional four adult fish were
stocked in September 1995. Some of these radio-tagged fish utilized habitats just downstream
of Hartland and probably would have used similar habitats available upstream if access had been
available. The objective of this stocking was to obtain life history information from stocked fish
because there were too few wild fish to study. This stocking was aimed at determining (1) habitat
utilization, (2) spawning habitat requirements, (3) possible fish aggregations prior to spawning,
(4) availability of rearing habitat utilized by resulting progeny, and (5) the feasibility of using
pond or hatchery-reared fish to re-establish razorback sucker in the Gunnison River. Data are
continuing to be collected. In addition, 316 juvenile razorback suckers were stocked into the
Gunnison River immediately downstream of Hartland Diversion Dam on 11 October 1995.
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