PROJ00206

• Contract/PO #: C153574
• Contractor Name: Longmont, City of
• Contract Type: Loan
• Water District: 5
• County: Boulder
• Bill Number: SB 88-30
• Loan Projects - Doc Type: Feasibility Study

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4. Discharge McCall Lake water into the Oligarchy Ditch via the Longmont
Supply Ditch. The lake water in the Oligarchy would be diverted into
Union Reservoir and exchanged up to Buttonrock Reservoir when exchange
potential is available in St. Vrain Creek.

5. An exchange for Burch Lake water. This would involve releasing water
from McCall Lake to the Oligarchy Ditch and booking over an equivalent
volume of water to the City's Burch Lake account from Oligarchy Ditch
users. The exchange water in Burch Lake could be treated directly at
the Wade Gaddis Filter Plant and used within the City's water distri-
bution system.

6. Discharge McCall Lake water into the Oligarchy Ditch via the Longmont
Supply Ditch. The McCall Lake water in the Oligarchy Ditch would be
used by downstream irrigators in exchange for an equivalent volume of
St. Vrain Creek water at the City of Longmont's North and South pipe-
line diversion points only when the Oligarchy Ditch is in priority to
legally divert water and when there is exchange potential available in
St. Vrain Creek between the Oligarchy Ditch headgate and the City's
pipeline diversion points.

For use of McCall Lake water in Options 1 and 3 there has to be adequate

excess capacity in the Longmont Supply Ditch and Oligarchy Ditch to transport

McCall Lake Water to the City's parks. The Longmont Supply Ditch has a capacity

of approximately 55 cfs and the Oligarchy Ditch has a capacity of 150 cfs near

McCall Lake. Monthly diversions for the Longmont Supply and Oligarchy Ditch for

1950 through 1986 are summarized in Tables 5.6 and 5.7, respectively. The maxi-

mum monthly diversion on the Longmont Supply Ditch was 2304 acre-feet in May of

1954 or an average of 37.5 cfs per day. The maximum monthly diversion on the

Oligarchy Ditch was 4180 acre-feet in June, 1953 or an average of 70 cfs per

day. Thus, the excess capacity available during maximum diversion months in the

Longmont Supply and Oligarchy Ditches to transport McCall Lake water was 17.5

cfs and 80 cfs, respectively. These release rates would allow McCall Lake to be
drained in two weeks. Therefore, the excess capacity in the Longmont Supply and
Oligarchy Ditches is available to enable Options 1 and 3 to be exercised.
For use of McCall Lake water in Options 2,4,5 and 6 there has to be 1) water
available in the Longmont Supply and Oligarchy Ditches and 2) water users in the

Longmont Supply and Oligarchy ditches located downstream of McCall Lake. The

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