8211

• UCREFRP Catalog Number: 8211
• Author: U.S. Bureau of Reclamation and Fish and Wildlife Service.
• Title: Final Environmental Assessment
• USFW Year: 1997.
• USFW - Doc Type: Providing Fish Passage at the Grand Valley Irrigation Company diversion Dam on the Colorado River.
• Copyright Material: NO

The historical range of endangered fish species in the Colorado River has been fragmented by
construction of diversion dams that serve as barriers to fish movement. Under the No Action
alternative, this condition would continue on the river unless fish passageways were constructed
under different programs. Under No Action, a self-sustaining population of endangered fish
would be less likely to develop in the Colorado River upstream from Palisade. Even if the
endangered fish were stocked upstream, the larval fish could travel downstream over the dams
and not be able to return as adults. Other endangered species are not anticipated to be affected
under the No Action alternative.
Under the preferred alternative, the Colorado squawfish and razorback sucker would have access
to river reaches upstream of the GVIC Diversion Dam. Also this alternative would allow testing
of this more natural appearing fish passage as opposed to concrete-raceway type passages. The
proposal would improve the chances of restoring upstream populations and the chances of
ultimate recovery of the fish. If needed, fish screens would be added to prevent adult and sub-
adult fish from entering the GVIC Canal.
These fish screens would have an indirect benefit of preventing some nonnative fish from entering
the canal and eventually ending up in gravel pits and backwaters where they might expend their
populations and eventually re-enter the river as competitors with the endangered fish. It is
recognized that some larval endangered fish, if successful spawning occurs upstream, would be
lost in the canal; but it is predicted that the net effect would be beneficial.
The draft EA served as a Biological Assessment under the Endangered Species Act. The
proposed action would not affect threatened or endangered species with the exception of the
Colorado squawfish and the razorback sucker. These fish and their critical habitat may be
affected but in a beneficial manner. The biological opinion (U.S. Fish and Wildlife Service, 1997)
on the project supported this conclusion as well as conclusions that other endangered species
would not be affected.
Historic and Cultural Resources
The GVIC Diversion was constructed in the early 1880's but a flood destroyed the original
headgates in 1898 and were replaced in 1901 by the current structure (FLO Engineering, Inc.
1997). The original wooden headgate was replaced with a steel one in the winter of 1899-1900.
In the 1940's, a concrete cap was poured over the top of the original dam, and the original
wooden cribbing diversion dam was modified to add a concrete cutoff wall on the upstream side
of the dam in about 1980. The GVIC canal system itself is considered eligible to the National
Register of Historic Places, primarily based on its importance in the settling of the Grand Valley.
An evaluation of the diversion dam itself is ongoing. Initial conclusions are that the diversion dam
(Cultural Resource site number 5 ME4665) is eligible to the National Register of Historic Places
under two criteria: its association with the Grand Valley Canal, the first Grand Valley area
irrigation project and as a resource that embodies the distinctive characteristics of a method of
18