7344

• UCREFRP Catalog Number: 7344
• Author: Veenhuis, J. E. and D. E. Hillier.
• Title: Impact of Reservoir-Development Alternatives on Streamflow Quantity in the Yampa River Basin, Colorado and Wyoming.
• USFW Year: 1982.
• USFW - Doc Type: Lakewood, Colorado.
• Copyright Material: NO

The upstream Vidler transmountain diversion could have varying effects (ta-
bles 22 through 26) on the flow at Craig. For the historical condition with 100
percent of transmountain diversions (table 22), the 5-year low flow (80-percent
exceedence probability) could decrease to zero for 3 months. Simulated historical
monthly streamflows at the laO-percent water-use allocation (table 26) could also
be significantly reduced by inclusion of the Vidler transmountain diversion.

Model-simulated historical monthly streamflows for control point 25 (conflu-
ence of Yampa River and Milk Creek) are presented in tables 27 through 31. This
site is located approximately 10 river miles upstream from the damsite of the pro-
posed Juniper Reservoir (fig. 1).

At the confluence of the Yampa River and Milk Creek, the flow statistics are
similar to the upstream Yampa River at Craig, Colo. (control point 15), with only
the addition of flow from Milk Creek and return flow from Craig Reservoir diver-
sions. Reservoir-development options 1 and 2 were similar in effect, with less
mean annual flow for option 2 due to additional reservoir storage upstream. For
reservoir-development option 3, the larger flow statistics reflect the Juniper and
Cross Mountain Reservoir downstream demands~ In reservoir-development option 4,
the downstream demands were nonexistent, and the flow statistics decreased at this
site. There also was a decrease in flow statistics as the allocation percentages
increased (tables 28 through 31), but to a much smaller degree. The absence of a
downstream demand could allow more water to be retained in Craig Reservoir and
other upstream reservoirs and less water to be released.

Table 27.--Summary of simul.ated historical. monthl.y streamfl.ows~
control point 25 (confl.uence of Yampa River and Mil.k Greek)3
for simul.ated historical. conditions and with
100 percent of transmountain diversions

[FLOW VALUES: A=MEAN; B=MEDIAN; and C=80-PERCENT EXCEEDENCE. Underscored values
are less than simulated historical conditions without transmountain diversions]
FLOW MONTHLY FLOWS, IN CUBIC FEET PER SECOND
VALUES OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT
SIMULATED HISTORICAL CONDITIONS
A 150 278 286 223 275 564 2349 5571 5088 794 125 133
B 122 279 289 267 273 565 2373 5696 4996 498 99 133
C 76 218 259 109 261 528 1763 4409 3240 147 43 32
SIMULATED HISTORICAL CONDITIONS WITH 100 PERCENT OF TRANSMOUNTAIN DIVERSIONS
A 71 174 200 144 197 486 1965 5180 4701 539 62 65
B 26 195 211 189 194 487 1982 5305 4605 235 23 18
C 4" 38 170 II 183 450 1451 1f618 2849 11 4 4

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