8215

• UCREFRP Catalog Number: 8215
• Author: U.S. Fish and Wildlife Service.
• Title: Final Environmental Assessment
• USFW Year: 1997.
• USFW - Doc Type: Management and Control of Noonative Fish Species in Floodplain Ponds of the Upper Colorado and Gunnison Rivers.
• Copyright Material: NO

Assessment was written on these "Procedures" (Maddux 1996) and resulted in
a decision of a Finding of No Significant Impact. The Colorado Division of
Wildlife and U.S. Fish and Wildlife Service intended to reach a balance
between providing sportfishing opportunities to Colorado anglers in western
Colorado while efforts are taken to recovery the endangered Colorado River
fishes. The Colorado Division of Wildlife (Division) is actively seeking
ways to provide warmwater fishing opportunities in the floodplain ponds
along the Upper Colorado and Gunnison rivers. For example, the Division has
already explored the possibility of raising the berms at Federal Emergency
Management Agency (FEMA) specifications on ponds such as Corn Lake, Duke
Lake, and Upper Connected Lake so that they would be out of the 50-year
floodplain and can be stocked under the "Procedures" (See Item B(2) on page
6 of Colorado Division of Wildlife et al. .1996). These waters are
particularly important in the Grand Valley because they provide recreational
fishing opportunities for youngsters and others through programs such as
"Pathways to Fishing".
C.
The cottonwood-willow riparian zone in the floodplain of the Upper Colorado
River is primarily (90%) in private ownership (Beidleman 1978). None of the
ponds in private (or public) ownership will be chemically treated to remove
nonnative fishes without the permission of the landowners. Therefore, no
adverse impact will occur to landowners.
Floodplain to Prevent Chronic Escapement of Nonnative Fish Species. Under
this alternative, mechanical devices (i.e., screens or traps) would be
installed in floodplain ponds with an outlet to either the Colorado River
or Gunnison River.
Only a small percentage of ponds along the Colorado River (12.7% of 253
ponds) was reported to have an outlet (10 with spillway, 20 with culvert
overflow, and 2 with standpipe) by Mitchell (1995). About the same
percentage of ponds along the Gunnison River (13% of 61 ponds) was reported
by Mitchel l (1995} to have an outlet to the river (8 with culvert overflow) .
Since only 40 ponds were reported by Mitchell (1995) to have outlets to
either the Colorado River or Gunnison River, chronic escapement of nonnative
fishes could not be controlled from the majority of ponds (268) without
outlets. Therefore, this alternative could not serve as a primary method
for controlling the chronic escapement of nonnative fishes.
However, the Recovery Program participants recognized that installing
screens or traps at ponds with outlets would be a good method for reducing
the numbers of nonnatives that could escape into the river. Some of these
floodplain ponds will have mechanical devices installed as a preventive
control measure. Earlier in this Environmental Assessment, it was stated
that about 20% of the floodplain ponds connect with the Colorado or Gunnison
rivers annually (Mitchell 1995). Installation of mechanical control devices
would not be practical on these ponds. Mitchell (1995) also reported that
40% of the floodplain ponds connect with the river in one out of 10 years.
Installation of mechanical control devices might be also questionable on
these ponds. Therefore, this method of controlling escapement of nonnative
fishes will be considered on a case-by-case basis and used when practical
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