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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of high flow, and (3) in other months of the growing season, shortages of some
magnitude occur in all years, The monthly shortages cited in item (3) cause
cumulative shortages over all the months of the growing season of 25,000 acre-feet
in typical low-flow years, 10,000 acre-feet in typical normal-flow years, and 6,000
acre-feet in typical high-flow years, Further, peak shortages occur in the month of
July, when the monthly shortage amounts to about half of the cumulative shortages
for all the growing season,

Section 6: Water Available for Development

Water available for development is water not presently being diverted for use. It is
potentially available to close the gaps between actual diversions and minimum
diversion requirements. Estimates of the quantities of water available for develop-
ment were made for the Tongue Creek basin and for the neighboring basins of
Leroux Creek and Overland Ditch, The methods were different in the case of the
Tongue Creek basin and the two neighboring basins,

The basin operation model was used to determine how much water, month-by-
month, leaves the Tongue Creek basin as outflow into the Gunnison River. From
October through March, average monthly outflows amount to 200 acre-feet in
years of low flow, 450 acre-feet in years of normal flow, and 530 acre-feet in years
of high flow, In May and June, monthly outflows into the Gunnison River amount
to 2,100 acre-feet in typical low flow years, 3,300 acre-feet in typical normal flow
years, and 10,300 acre-feet in typical high flow years, For the two months,
combined outflows amount to 4,200 acre-feet, 6,600 acre-feet and 20,600 acre-
feet, in years of low, normal and high flows,

For the Tongue Creek basin, the consultant studied availability of water for
development using a basin operation model for which stream flows, estimated
return flows and diversion requirements were data inputs, The model computed the
quantities of unused water available for development on a month-by-month basis.
Water was considered to be available in a given month (1) once all demands are met
(from streamflows and return flows) and (2) surplus water leaves the basin because

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