8192

• UCREFRP Catalog Number: 8192
• Author: Wydoski, D.
• Title: Review of Report Regarding Evaluation of Gravel-Pit Ponds.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

4. Notch Dikes and levees Protectinq Gravel Pits. Reconnect former
floodplain habitats without deep depression ponds with the river to
enhance or restore the natural function of the river ecosystem. Such
former floodplain habitats have been separated from the river by levee
construction so it would be cost-effective and practical to acquire
rights to use land through easements or fee-title so the floodplain
could be reconnected with the river by excavating a notch. Although
it might be desirable to implement recommended river flows that would
inundate floodplains in the spring during May and June to provide off-
channe 1 habi tat for endangered fi sh, adequate flows mi ght not be
available frequently enough to benefit recovery of the endangered
fi shes. Therefore, notchi ng old 1 evees and di kes at strategi c
locations could provide some level of protection from flooding to
agricultural land, and residential and recreational structures (i. e.,
set-back dikes) and also provide access to floodplain habitats to
various life stages of endangered fishes. Dikes and levees
constructed to protect gravel-mining operations could be removed
following gravel mining to permit reconnection of the floodplain and
the river. The floodplain could then function as it did historically,
recreating new in-channel habitats. Some of the features created
would be flow-through side channels that might create a complex of
habitat types.

An anci 1 1 ary benefi t for modi fyi ng gravel- pi ts protected by 1 evees and
dikes to allow these habitats to communicate with the river during
runoff is flood control. In addition to isolating off-channel,
productive areas from aquatic organisms, levees and dikes have reduced
the channel wi dth and thus the ri ver' s abi 1 i ty to convey 1 arge volumes
of water during runoff. In some areas protected by levees and dikes,
runoff water now inundates adjacent low-lying areas at lower
di scharges than did hi storical ly. Flood-control management strategies
would be to notch levees and dikes to allow inundation of low-lying
areas and also reclaim gravel-pit ponds as sloped terraces or side
channels. Restoring gravel pits to function as historical terraces or
side channels may not only benefi t nat i ve fi shes but may actually
provi de county, state, and federal agenci es more fl exi bi lity ill
managing and coping with spring runoff during high-flow years along
riparian areas where anthropogenic activity occurs. In low-density
population areas, specific riverine reaches that are now constricted
could be targeted to be restored as terraces or side channels to serve
as "relief valves" and allow runoff waters to spread that would reduce
flooding and minimize damage to private land and structures in
adjacent areas. It is believed that natural lateral expansion of the
floodplain and river-basin management are perhaps the best methods of
flood control because of the growi ng awareness of i nadequaci es of
structural measures to control floods (Welcomme 1985).

5. Acquire Gravel-Pit Ponds Presently Connected to the Mainstem Colorado
River. The Recovery Program should investigate opportunities to
modify and rehabilitate Hotspot and Pickup ponds (river mile 174.4 and
175.0, respectively) to enhance seasonal habitat for endangered fish
and eliminate perennial habitat for nonnative fishes. A portion of

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