7796

• UCREFRP Catalog Number: 7796
• Author: Burdick, B. D.
• Title: Conceptual Management Plan for Habitat Enhancement in Flooded Bottomlands, Escalante State Wildlife Area, Gunnison River Downstream of Delta, Colorado.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

separating it from the river with heavy machinery (back hoe). This work would
be accomplished during low-flow periods prior to or after runoff.

Potential Impacts from Operations on Native Flora and Fauna
No razorback sucker have been reported recently in the immediate area of
these two proposed sites at the Escalante SWA. However, a small remnant
population of Colorado squawfish resides in the Gunnison River downstream of the
proposed area. One radiotagged Colorado squawfish was located at river mile 48.4
in the Gunnison River in 1993 (Unpublished data, USFWS). This same fish was
located at river mile 59.1 in May 1994, indicating that it had passed by the
Escalante SWA sometime between October 1993 and May 1994.
At the present time, it is anticipated that the operations at the sites
will benefit native endangered fishes. If necessary, operations will be modified
to benefit native endangered fishes.
PROPOSED EVALUATION
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Factors to be Evaluated
Evaluations are essential to determine if the action was beneficial,
detrimental, or had no affect on the intended target species. Each of the five
selected sites were intended to be "pilot" or "test" sites for experimentation.
The evaluation of these five sites will provide information to help in the
selection of future bottomland sites that will be most suitable for habitat
enhancement and restoration, and to improve designs to reconnect bottomlands to
the river. Therefore, adaptive management will be employed to make necessary
refinements in design and operation.
The specific factors to be evaluated differ greatly at the two sites at
Escalante SWA because of the nature of the proposed development.
Site 1. The proposed development at Site 1 was designed to take advantage
of a former natural riverine feature now isolated from the river. Although this
extensive development is not economical or practical at all potential sites, it
provides a variety of habitats and separate experimental units that are needed
to determine ecological requirements of early life stages. Few floodplain areas
provide this opportunity. Several questions still need to be answered regarding
factors that are limiting some of the endangered fishes. Except for the bonytail
which is functionally extirpated in the upper Colorado River basin, immediate
concern is for the recovery of the razorback sucker.
Waterborne selenium levels in the Gunnison River near the Escal ante SWA are
' elevated (range at study sites: 3-7 ug L-1; Cooper and Severn 1994c). Selenium
and other trace elements are thought to impair reproductive success of razorback
sucker and larval fish (Appendix B). To date, only laboratory tests using
reconstituted water from sites known to have levels of trace elements that impair
early life stages of endangered fishes in the Colorado River basin have been
conducted. Laboratory tests of seven trace elements (vanadium, zinc, selenite,
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