8232

• UCREFRP Catalog Number: 8232
• Author: Burdick, B. D.
• Title: Evaluation of Fish Passage at the Grand Valley Irrigation Company Diversion Dam on the Colorado River Near Palisade, Colorado.
• USFW Year: 1999.
• USFW - Doc Type: CAP-17,
• Copyright Material: NO

Study Timetable and Direction
This evaluation was originally developed and scheduled for three years.
The first two years (FY98 and FY99) were planned for field collections and FY2000
for preparing the final report. Study direction was changed in August 1998 when
the RIP Management Committee discontinued all field work previously scheduled for
the spring, summer, and fall of 1999 (March through September). The only field
work scheduled for FY99 was conducted during October 1998. Analyses of the field
data and preparation of the final report were accomplished in FY99 instead of
FY2000. To accomplish the necessary objectives for a 2-year field evaluation,
the field methodology and study design were initially developed for 2 years of
field work, not 1 year. Consequently, less information was collected because one
year of field work was canceled, and therefore, study objectives were not
sufficiently addressed and some of the end products were not met.
STUDY AREA
This evaluation included the Upper Colorado River from RM 187.6 immediately
downstream from the Price-Stubb Dam (RM 188.3) to Loma (RM 152.6) and the Lower
Gunnison River--RM 3.0-0.7. Fish collections with electrofishing were conducted
exclusively in a 4.6-mile section of the Colorado River from RM 187.6 to RM
183.0. Telemetry from boats was conducted from Colorado River RM 185.5 to RM
152.6 and the lower 2.3 miles of the Gunnison River (Figure 2).
METHODOLOGY
Field efforts for this evaluation relied on two separate techniques, mark
and recapture and telemetry, both applied independently to determine if sub-adult
and adult fish would use the passageway to pass over the GVIC Diversion Dam. The
first method involved collecting native and nonnative fish with electrofishing
and marking them from the first 2 miles of river immediately downstream of the
diversion dam. Although the passage structure was constructed to provide passage
primarily for Colorado pikeminnow, surrogate native and nonnative fishes were
also marked and tagged because Colorado pikeminnow numbers inhabiting the study
area were low and determining if and when pikeminnow would use the fish passage
at this site might take considerable time.
Sub-adult and adult fish of the most common large-sized, native fishes
(flannelmouth sucker, bluehead sucker, and roundtail chub) were initially
inserted with a Passive Integrated Transponder (PIT) tag and released. An
administrative decision was made in mid-August 1998 to discontinue field work for
the following year. Use of PIT tags was discontinued and it was decided that a
short-term mark (i.e., fin clip) would suffice for the remainder of the study.
Therefore, between 3 April and 27 April and between 17 July and 20 August 1998,
all native fishes captured were PIT tagged. Between 24 and 28 August 1998, all
native fishes were fin clipped. Other common sub-adult and adult nonnative
fishes such as common carp and white sucker that were captured were marked with
an external, individual, serially-numbered Floy~ "spaghetti" tag in the dorsal
musculature. Rainbow trout, brown trout, and sucker hybrids (white sucker X
flannelmouth sucker, white sucker X bluehead sucker. and bluehead sucker X
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