9314 ‎(2)‎

• UCREFRP Catalog Number: 9314
• Author: Wick, E. J. and J. A. Hawkins.
• Title: Colorado Squawfish Winter Habitat Study.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

1
' to decrease approximately 0.2 feet during midwinter, ice-covered conditions.
Overall productivity of the winter ecosystem appeared to be maintained by
natural flaws which provided diverse low velocity habitats (embayments,
' backwaters, pools, and runs). During Winter 2, this diversity appeared to be
best maintained in the 200-300 cfs flaw range in mid-winter during ice cover.
Flaws below this range would result in less than optimum depth in preferred
embayment habitat while higher flows flood and eliminate these habitats.
Alterations in flow during winter due to water project impacts must be
analyzed with respect to the portion of the winter in which they may occur.
Effects will be different due to current ice conditions, air temperature,
precipitation, and discharge. Reductions below natural baseflow at initial
ice formation should be avoided. At this time actual discharge is already
decreasing because water is being tied up in ice formation. Maintaining
' natural flaws during the initial freeze period in late November or early
December would insure that ice cover forms over the maximum amount of usable
winter habitat. A key flaw consideration during mid winter is maintaining the
natural conditions of steady discharge with little fluctuation. Flaws
normally do not fluctuate more than 140 cfs above or belaW the annual mean
during the period from mid-December through February. It is important to
avoid unnatural discharge fluctuations that could remove natural ice cover.
can be the most critical
which usually occurs in March
The ice-out period
,
,
part of winter. During this time, water surface elevations and effective
depth decrease even though discharge is maintained. Therefore, any reductions
in flow should be avoided until ice is completely out.
t

1

1

1

I ix