1006

• UCREFRP Catalog Number: 1006
• Author: Resource Consultants, I.
• Title: Biological Assessment Green Mountain Reservoir Water Marketing Program.
• USFW Year: 1985.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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The cumulative impact of the Green Mountain depletion, plus that of
other recent or planned development (Table 4), would cause significant
reductions {10-20%} in monthly and instantaneous flow in the Black Rocks
area. Average flows in May and June would be reduced 15 and 12 percent,
respectively. These reductions may well al ter temperature patterns, or
other habitat parameters, and conti nue favoring more roundtail chubs in
that area, causing the increased breakdown of reproductive isolating

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Bonyta i 1 Ch ub
The bony tail chub is nearly extinct in the portions of the Colorado
River of concern here and, therefore, the proposed project would have no
effect on this species.
Razorback Sucker
The razorback sucker is a candidate species and may be listed in
the near future.
The depl etions from the Colorado River discussed above would not by
themsel ves cause negative impacts to razorbacks for the reasons
discussed for Colorado squawfish.
The cumulative effect of the Green Mountain Water Sale depletion
pl us other potential depl etion as shown in Tabl e 4 could be a probl em
for razorbacks. The cumul ative depl etions that would affect the area
above Grand Junction are shown in Table 4, and vary from about 187.2 cfs
in September to 957 cfs in June. This amount of cumulative depletion is
rather large and, therefore, may affect razorback sucker reproductive
success in the area near De Buque.
It is difficult to say at thi s time if the razorback popul ation
above Grand Junction is already doomed to extinction because the river
has been depleted sufficiently so that reproductive success is no

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