PROJ00147

• Contract/PO #: C153637
• Contractor Name: North Poudre Irrigation Company
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: SB 92-87
• Loan Projects - Doc Type: Feasibility Study

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exchange several thousand acre-feet of water Is not great. Thus, transfer of the
water does not appear to be feasible or desirable at this point In time.

Another drawback Is the fact that no definite decision has been made to upgrade
Halligan Reservoir. Even If It Is enlarged, a likely schedule would not bring
Halligan on line for another 10 to 16 years.

Temporary exchanges or transfers between other water users In the basin are
always possible and are routinely made at this time. These transfers of water
however are short term solutions for users that may be short on water one year
and can not be counted on for long term Income.

B. Water Utilization. Reservoir No. 6 and No. 6 are off-stream reservoirs which
are filled from surface water rights from the Cache La Poudre River. Both are
Irrigation storage reservoirs In the North Poudre System but are not main storage
reservoirs as are Halligan, Park Creek, or Reservoir No. 16. The past and
current use of water stored In No. 6 and No. 6 has been to Irrigate lands that
lie Immediately below the Reservoir. No municipal water use has ever been
provided from these reservoirs. However, the future plans for No. 6 would
Include allocating a significant portion of the water for municipal water supply.
Water Is normally not stored In No. 6 and then diverted to other reservoirs for
use as Is the case with many of the plains reservoirs. This will probably change
after rehabilitation as North poudre would plan to exchange or sell a portion of
the water stored In No. 6 to other water users that are within the Cache La
Poudre system. Transfer of a portion of the water out of the system Is a
possibility depending on the outcome of the current litigation with the City of
Thornton and their plan to divert water out of the basin.

C. Firm Yield. The firm or safe yield of a reservoir Is generally defined as "the
maximum quantity of water which can be guaranteed during a critical dry period".
The safe yield of Reservoir No. 6 was not evaluated by analysis of the available
flow of water In the Cache La Poudre or the North Fork of the Cache La Poudre
Rivers. It was evaluated only by review of the past history or record of filling
of the reservoir. A summary of the water records are shown on Figures IV -I,
IV-2, and IV-3 of the text.

From a review of Figure IV-1 and IV-2 It can be seen that both reservoirs have
been filled to near capacity most years and significantly drawn down during most
of the years. Figure IV-3 shows the monthly reservoir water levels over a two
year period and was plotted to show the a typical use pattern.

The maximum fill level for Reservoir No.6 during the years 1960 to 1991 Is Gage
Height 26.0 feet. The reservoir has been filled to Gage Height 26 feet or above
In 10 of the 40 years of record studied; to Gage Height 18 feet or above 29 of
the 40 years; and, to Gage height 14 feet or above 32 of the 40 years. The
lowest fill level of record for Reservoir No. 6 Is 0.0 feet In 1964, 1966, and
1966, and In 1966 and 1980. The reservoir was drained In 1980 for rehablllta-
t10n and the period from 1964 to 1966 was a very dry period throughout the
region.

PAG! I
Chapter IV - No. 6 !'eulblllty