PROJ00370

• Contract/PO #: FS0031X
• Contractor Name: Yampa Project DNR 1972
• Contract Type: Miscellaneous
• Water District: 0
• County: Moffat
• Loan Projects - Doc Type: Feasibility Study

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III. FEASIBILITY OF ENLARGING THE ELKHEAD CREEK RESERVOIR
1. Hydrology. Based on the stream flow record at the U.S. Geological
Survey's Gaging Stations No. 9-2450 and 9-2455, monthly average inflow
hydrographs at the dam site are derived and plotted on page A-I in
Appendix A. Mass curves of reservoir inflow versus outflows including
the release for four 350 MW units operation are presented on page A-2

to demonstrate that there is sufficient stream flow in the Elkhead

Creek to fill up the reservoir each and every year after the reservoir

is lowered annually for all the requirements.

During the low stream flow period, July 1962 thru May 1965, reservoir
operation studies were made as shown in Tables A-I and A-2 for both

the (2) 350 MW and (4) 350 MW operation conditions. In the case of

(4) 350 MW operation, it is found that with an added dam height of

24 feet, the minimum reservoir level after 90 days withdrawal for

plant operation will not be lower than elevation 6340.5 feet which

is the normal pond level proposed originally by the Colorado Division

of Wildlife.

The standing of water rights which will affect the availability of

stream flow for reservoir storage was investigated and evaluated

with results shown in Appendix B. It concluded that the Elkhead Creek
contains sufficient stream flow to fill the reservoir and maintain

the reservoir level. The present diversion from the creek amounts

to approximately 50 cubic feet per second. However, two potential

problems do exist; two reservoirs have been proposed and both hold

conditional water rights on the Elkhead Creek that are senior to

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