WSP06609

• File Number: 8141
• Description: Fryingpan-Arkansas Project
• State: CO
• Basin: Arkansas
• Date: 1/1/1981
• Author: Wright Water Enginee
• Title: Operational Study of Ruedi Reservoir Releases For The Municipal Water Study of Battlement Mesa
• Water Supply Pro - Doc Type: Report/Study

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Return flows from Battlement Mesa would have an effect on downstream TDS.
Table 6 shows this effect on the Colorado River at Cameo. To develop the
TDS values for Cameo in Column 7, it was assumed that Battlement Mesa return
flows from the sewage treatment plant would increase TDS by 200 mg/liter.
lrri gat i on return flows wou 1 d be 5 times as concentrated as the Co lorado
River water. The changes in TDS are shown for every month in Table 6 be-
cause the effect would occur whether or not water is purchased from Ruedi
Reservoir.

Table 7 shows the effect of Battlement Mesa water sales from Ruedi Reservoir
on reservoir water surface elevations. Column 5 indicates the change in
elevation that would have occurred if sales had been made in water years
1976-1978 assuming no change in reservoir operation to reduce the impact of
these sales. The small drawdown shown in Table 7 can be avoided by prudent
operational procedures in conjunction with the proposed sale which would
result in no appreci able effect on the reservoir during period of peak rec-
reational use. The changes in elevation shown in Column 5 cannot be added
to obtain total drawdown of the reservoir because of refilling that occurs
during the year.

Summer water temperatures in the Fryingpan River below Ruedi Reserivor are
an average of 120F cooler as the result of reservoir releases according to
the 1975 Final Environmental Impact Statement on the Fryingpan-Arkansas pro-
ject. It is anticipated that the relatively small releases required by the
proposed sale would not further alter summer water temperatures.

Comparison of the frequency of reservoir releases for Battlement Mesa during
the month of October with the frequency of releases for Colony Shale Oil
Project during the same month shows a substantial reduction in frequency for
the Battlement Mesa release. This reduction in required releases for Oct-
ober is a result of sufficient return flow credits to offset or replace the
October diversions for Battlement Mesa.

It is recommended that the repl acement water agreement on Ruedi Reservoir be
for the amount of up to 1200 acre feet per year. A safety factor is not
recommended because in times of drought it is planned that reasonable water
conservation practices would be initiated and, if necessary, lawn irrigation
would be curtailed.

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