7800

• UCREFRP Catalog Number: 7800
• Author: Burdick, B. D.
• Title: Conceptual Management Plan for Habitat Enhancement in Flooded Bottomlands, Gravel Pit at 29-5/8 Road, Colorado River Near Grand Junction, Colorado.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

1

1

1
1
1

r

of the lack of the right sizes of food organisms at the right time and in
sufficient quantity (Wydoski and Wick 1994).
Flooded bottomland habitats occur in broad valleys along low gradient
stream reaches. Bottomlands are off- or out-of-channel habitats that include
oxbow lakes, former side channels in broad valley floodplains, ponds, and wetland
depressions. During high flow events, some of these off-channel features were
temporarily connected to the river. Former natural riverine features could be
integrated back into the historic floodplain by removing portions of man-made
dikes or natural obstructions (e.g., gravel/sand bars).
Although gravel pits are artificial environments that are typically diked
and isolated from the mainstem river, they comprise a large proportion of pond
habitats created by gravel-pit mining in the floodplain in some river corridors
along the Upper Colorado River. Gravel mining operations along the Colorado
River in the Grand Valley between Palisade and Loma, Colorado (15- and 18-mile
reaches), between Rifle and Debeque, Colorado, and near Delta, Colorado on the
Gunnison River have created numerous gravel pits that vary in size, depth, shape,
and orientation to the mainstem river. For example, in the 100-year floodplain
from Palisade to Loma, approximately 15% of the total surface area (3,952 acres)
is comprised of ponded water created either from gravel mining or sewage
treatment plants (Unpublished data from the Bottomlands Survey and Inventory,
1994, U. S. Fish and Wildlife Service [USFWS]). Though this percentage appears
to be low, historical aerial photos of this same area reveal very little gravel
mining activity as late as 1954 when less than 0.5% of the same area was
comprised of ponds. More importantly, these ponds are located in the former
floodplain. Even more dramatic is the approximate 15 miles of man-made dikes in
this 33-mile stream reach (Unpublished data from the Bottomlands Survey and
Inventory, 1994, USFWS) that effectively prevent inundation of potential off-
channel habitats and fish access to historic floodplain habitat. There were no
gravel pits either in 1954 (Appendix A: Photo 1) or in 1937 (Appendix A: Photo
2) and only 'virgin' floodplain existed where the 29-5/8 Road gravel-pit pond
site occurs today.
During high flow events, some of these ponds have been temporarily
connected to the river allowing access to fish. However, these ponds that do not
have permanent connections to the river have also trapped fish following
recession of high flows. Ponds that are reconnected to the river are less likely
to trap endangered fishes. Integrating ponds created from gravel-pit mining into
the historic floodplain by removing portions of dikes and re-establishing
connectivity to the river may provide off-channel habitats which are essential
for effective management of the riverine ecosystem and recovery of endangered
fishes.
Protection, restoration, and enhancement of inundated bottomland habitat
along mainstem riparian corridors are believed to be important for recovery of
razorback sucker. Riparian enhancement in the upper Colorado River basin can be
accomplished by providing sufficient flow to inundate bottomlands in a manner
that approximates the natural hydrograph. If sufficient flows cannot be obtained
regularly, dikes and levees should be breached at intervals to allow inundation
of lowlands during the spring high flow period. To reconnect floodplain habitat
where existing dikes occur, "set-back" dikes may have to be constructed to