PROJ00040

• Contract/PO #: C153446
• Contractor Name: Grand Mesa Water Conservancy District
• Contract Type: Grant
• Water District: 0
• County: Delta
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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The second non-structural approach, as indicated at the beginning of this section,
would involve changes in the locations where releases from existing reservoirs are
used. Return flows are a significant proportion of the total supply of water for
meeting crop irrigation requirements. Much of the water which reenters stream
channels as return flow is diverted a second time, but a portion of return flows
come back to the channel too far downstream to be diverted a second time. These
unused return flows are discharged into the Gunnison River and are, in effect,
"lost" insofar as irrigators within the Tongue Creek basin are concerned.

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It is estimated that more effective use of return flows could reduce average annual
water shortages in the basin by approximately 30 percent. The key to achieving a
reduction of this magnitude would be diverting water released from headwaters
reservoirs onto cropland at the farthest upstream locations where the water could
be used. The reasons why this is not currently being done and the difficulties
inherent in implementing such a change are discussed in the following paragraphs.

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The small reservoirs in the headwaters area are privately owned by holders of
storage rights. Holders of these rights apply water released from the reservoirs to
their farms, which are concentrated in the Lower Surface Creek service area
(lower basin). (The lands irrigated by reservoir releases are concentrated in the
lower basin because agriculture in the project area started earlier in the lower
basin than in the upper basin.)

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Under the prevailing arrangements for operation of the reservoirs, a holder of a
storage right does not necessarily receive water released from his reservoir. A
schedule of exchanges is developed annually by the Grand Mesa Water Users'
Association, whose members are holders of storage rights. However, farmers who
receive water released from a reservoir do hold a storage right, and the matter of
which reservoir is the source of the water the farmer receives is of secondary
importance. As a consequence of the concentration in the lower basin of lands
whose owners hold storage rights, approximately 4,300 acre-feet of return flows
from diverted reservoir releases are unused each year, on the average.

The consultant conducted an operation study based on a hypothetical reservoir

operation policy of using releases to meet all water requirements in the upper

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