9344

• UCREFRP Catalog Number: 9344
• Author: Camp Dresser & McKee Inc.
• Title: Replacement of the Plateau Creek Pipeline.
• USFW Year: 1996.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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between the USFWS flow rates and measured areas. The net change in habitat area due to District
diversions was also calculated for the four study sites and then extrapolated to net change in area
over the entire 1 S-mile reach by dividing the area within the four sites by 0.668. This extrapolation
is based on the USFWS finding that "...66.8 percent of all squawfish radiotelemetry locations in the
15-mile reach occurred within the four study sites..." (USFWS 1995, page 8). It was therefore
assumed in this analysis that squawfish locations were directly proportional to habitat area available;
so the area within the four sites would represent 66.8 percent of total habitat area in the 15-mile
reach.
The most preferred habitat types -eddies, pools, and backwaters -are shaded in Table 3.20. The
results of this evaluation show that expected effects on all habitat types over the 15-mile reach would
have averaged about 0.36 acres in habitat area reductions during the summer season and 0.25 acres
during the winter season out of a total of 84 to 96 acres, respectively. (extrapolating the areas in the
four sites to the full 15-mile reach as discussed above). For preferred habitat types, areas would
actually have been expected to increase by 0.02 to 0.40 acres out of a total for these habitat types of
5.1 to 10.7 acres (extrapolated to the full 15-mile reach).
As noted above, extrapolation of change in habitat area for the four study sites to the entire 15-mile
reach was based on the assumption that the change is most appropriately related to the percentage
offish found in those study sites (i.e., 66.8 percent). USFWS chose the four study sites because they
were known sites that the fish frequented. Implicit in that choice was the acknowledgment that other
reaches within the 15-mile reach probably do not contain the same relative frequency of preferred
habitat. In terms of reach length, the four study sites comprise 14.1 percent of the 15-mile reach
(USFWS 1995, page 8). If it is alternatively assumed that there is a linear relationship between the
study site reaches and the entire 15-mile reach based on reach length rather than fish locations, the
extrapolation of net change in habitat area for the four study sites to the full 15-mile reach would be
accomplished by dividing the areas within the four study sites by 0.141 rather than 0.668. Under this
alternate assumption, the maximum effect on all habitat types over the 15-mile reach would have
averaged 1.2 to 1.7 acres during the summer and winter seasons, respectively. Effects on the
preferred habitat types would have ranged from a 0.07 to 1.9 acre increase in habitat area.
In summary, a range of the expected effects on endangered fish habitat types in the 15-mile reach
that could be anticipated with the District's future water diversions is less than a 0.5 percent decrease
in overall habitat, and a 0.1 to 8.0 percent increase in preferred habitat, as shown in Table 3.21.
3.4 CONCLUSIONS
The hydrologic effects of the District's future diversions under the population and demand
projections presented have been identified in terms of depletions to the entire Colorado River Basin
and effects on the 15-mile reach at Palisade, Colorado. Conclusions drawn from these evaluations
may be summarized as follows:

CDM Camp Dresser & McKee B-21
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