7145

• UCREFRP Catalog Number: 7145
• Author: Inslee, T. D.
• Title: Spawning of Razorback Suckers
• USFW Year: 1981.
• Copyright Material: NO

In light of the above discussion, we recommend the following:
1) to maintain or increase the current 25% frequency rate of peak flows
(high day of the year) within the 30,000-40,000 cfs range (at State
line) for optimum production of Colorado squawfish young, and for
reducing numbers of introduced fishes,
2) to increase the frequency of years with peak flows in excess of 40,000
cfs (at State line) from the current one in 12 years (8%) to one in
four years (25%) to improve razorback sucker reproduction, maintain
complex habitats for adult Colorado squawfish and backwaters for young,
and flush otherwise protected habitats of undesirable, introduced
fishes,
3) and the remaining 50% of the years should have peak flows in excess of
22,000 cfs (at State line) to provide minimally acceptable production
of Colorado squawfish young, to keep tamarisk from becoming rooted in
sand bars so as to prevent further channelization of the river, and to
keep in check the yearly abundance of introduced fishes.
Peak flows of sufficient magnitude and frequency are needed in the 15-mile
reach to provide benefits there as well as to help provide the target peak
flows at the State line. To arrive at corresponding flows for the two
reaches, average peak flows in the 15-mile reach were calculated from
several years during which the target peak flows at the State line were
similar (see Tables 7, 8 and 9). Recommended peak flows in the 15-mile
reach are as follows:
1) 20,500 to 23,500 cfs in at least one of four years (25%),
2) peak flows in excess of 23,500 cfs in at least one of four years (25%).
3) and 14,800 to 20,500 cfs to occur at a frequency of no more than two of
four years on average (50%),
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