7332

• UCREFRP Catalog Number: 7332
• Author: Valdez, R. A., et al.
• Title: Final Report Habitat Suitability Index Curves for Endangered Fishes of the Upper Colorado River Basin.
• USFW Year: 1987.
• USFW - Doc Type: \
• Copyright Material: NO

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FORWARD

In 1984, the u.s. Fish and Wildlife Servi ce chose to implement the
Instream Flow Incremental Methodology for the endangered Colorado River fishes.
This process included: (1) identifying the habitat needs of selected fish
species; (2) describing the physical nature of the important habitat types; (3)
simulating the dynamic aspects of river water quality and quantity; and (4)
simulating the dynamic aspects of key riverine environments determined to be
critical for the continued well-being of the endangered Colorado River fishes.
Ultimately, this analytical process should lead to the ability to "game" with
the water management aspects of the riverine system in order to evaluate
various alternative water use and routing schemes and express them in terms of
their impact upon the quality and quantity of the fishes' habitat. Prior to
1984, much experience had been gained on large rivers in the Pacific Northwest
and Alaska on the use, calibration, and verification of simulation models
describing the physical dynamics of the riverine habitat of Pacific salmon and
inland trout species. Earlier attempts (pre-1983) in applying hydraulic
simulation techniqUes to the Green, Yampa, and Colorado rivers also resulted in
valuable experience with hydraulic measurement techniques and stream discharge
computations along transects wi thin the main channel in these large, turbid
rivers. However, little was known of the habitat requirements necessary for
the successful completion of all life history phases of the endange~ed Colorado
squawfish, humpback chub, bonytail chub, and razorback sucker in the system.

Due to the endangered status of these fish species and the importance of
water use and management to the people of the Upper Colorado River Basin
states, it was felt that an integrated basinwide analysis process was needed.
Such a process would allow the various water management interests and the
resource agency biologists to evaluate existing and proposed water development
and water routing schemes wi thin the upper basin from an endangered species
protection viewpoint. The Service's goal is to be able to quantify the effects
of these various water management schemes upon the quality and quantity of the
fish habitat both spacially and temporally throughout the basin. Such an
analytical system was chosen because the flexibility of such a system would
allow for continual evaluation of evolving water use and management schemes.
The other flow analysis option considered was that of reach evaluations
throughout the entire basin for the purpose of establishing fixed downstream
flow delivery targets (minimum flows) which would protect in perpetuity the
endangered fishes' habitats. This setting of so-called minimum or target
"standards" would place constraints upon the future development and management
of water but would also guarantee protection of existing habitat. However,
_such an approach would provide virtually no flexibility to deal with changing
water needs in the basin or the ability to cope with periodic droughts and the
major uncertainty as to the basin'S annual water supply, which is driven
primarily by climatic conditions. In reality, a combination of the two
approaches may be used, Le., setting standards initially at a few critical
sites to protect these habitats until a basinwide system for describing habitat
quality and quantity is in place.

Several parallel activities were ini tiated to achieve the goal of
developing an integrated fish habitatjWater use and management process for the
Upper Colorado River Basin. These included the development of:

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