8169b

• UCREFRP Catalog Number: 8169b
• Author: Brookshire, D. S., M. McKee and G. Watts.
• Title: Draft Economic Analysis of Proposed Critical Habitat Designation in the Colorado River Basin for the RRazorback Sucker, Humpback Chub, Colorado Squawfish, and Bonytail.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

endangered and two are candidates for listing. The large geographical extent of the Basin
also supports a variety of habitats; from the Rocky Mountains to the desert southwest.
B. Current Status of the Colorado River Basin
The Basin biodiversity in the past relative to the current biodiversity is central to the issue of
proposing the designation of critical habitat. Over the last century, the physical
characteristics of the Colorado River Basin have been altered. Historically, barriers to the
endangered fishes migratory habits in the basin were predominately natural rapids and swift
turbulent waters. While these natural barriers may have impeded fish migration, they were
not absolute impediments. The 1902 Reclamation Act lead to major dam development in the
Lower Basin. These dams and diversions have fragmented the river systems and obstructed
the fishes ability to migrate. This has resulted in substantial physical changes in the Basin.
Coupled with the development of diversions and dams has been the increased consumptive
use of water from the river basin. Developed irrigated land in the Basin is now in excess of
2.1 million acres. the steady- growth of urban areas in the Basin has also contributed to
increases in consumptive uses. These consumptive uses have lead to major depletions in the
river. These depletions have thus changed the nature of the Basin. Other changes in the
physical nature of the basin have come through activities that generate contaminants, mining
activities, channelization, recreation activities, and home sites along the river and the
introduction of nonnative fishes.
C. Values Associated with the Preservation of the Basin
In evaluating the proposed designation of critical habitat, ideally a formal efficiency base
benefit-cost analysis would be undertaken. The specification of the benefits and costs
requires that the market and nonmarket benefits and costs are known. It is the nonmarket
benefits of preventing further deterioration of the Colorado River Basin or improvements in
the physical nature of the Basin that are difficult to quantify. Further, the value in and of
itself of preservation of the four endangered species is unknown.
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