PROJC01804 ‎(3)‎

• Contract/PO #: C150138
• Contractor Name: Supply Irrigating Ditch Company
• Contract Type: Loan
• Water District: 0
• County: Boulder
• Loan Projects - Doc Type: Approval Letter

Supply Irrigating Ditch Co.
March 24-26, 2003.

Agenda Item 24e
(Updated March 28, 2003)

The Supplv Irriaatina Ditch Company
The SIDC is a mutual ditch company and a non-profit corporation registered in the State of
Colorado. There are 160 shareholders and 400 shares of stock. The SIDC has the power to set
annual assessments to be paid by the shareholders, the power to cut off water deliveries to
shareholders that fail to pay their assessments, and the power to offer stock for sale to pay
back assessments.

Water Riahts
The water rights owned by the SIDC include a direct flow right in amount of 92.2 CFS from St.
Vrain Creek, and a 51 % interest in the Beaver Park Reservoir. The Beaver Park interest
delivers approximately 800 acre-feet per year. Records of the State Engineer's Office (1997-
1999) indicate that the average annual volume diverted by the Supply Ditch has been about
9,500 acre-feet. The Knoth Reservoir has a 218 AF absolute and a 542 AF conditional right.

Proiect Description
During the study of Knoth Reservoir and Dam, the following alternatives were evaluated:

The no action alternative
1) Complete rehabilitation of the two dams to Gage Height 20 feet ($735,800)
2) Complete rehabilitation of the two dams to Gage Height 25 feet ($1,428,480)
3) Complete rehabilitation of the two dams to Gage Height 30 feet ($2,193,000)

Following is a summary of each alternative:

No Action Alternative.
This alternative was rejected because the need is apparent for some storage within the system
to increase the usable yield and to allow for more efficient operation of the ditch

Alternative 1 - Rehabilitate the dam to its current capacity (Gage Height 20 feet)
This alternative involves rehabilitation of the dam to approximately its current height and size,
which will store approximately 220 acre-feet. The total project cost is $735,800. This alternative
would not allow storage of the full conditional decree, and was rejected for that reason.

Alternative 2 - Raise Dam Crest To Gage Height 25 feet.
This alternative is similar to Alternative 1 in all respects except the crest of the dam will be
raised approximately five feet in elevation from gage height 20 feet to gage height 25 feet. This
increases the reservoir storage to approximately 360 acre-feet. The total project cost is
$1,428,480. This alternative would not allow storage of the full conditional decree, and was
rejected for that reason.

Alternative 3 - Raise Dam Crest To Gage Height 30 feet.
This alternative is similar to Alternatives 1 and 2 in all respects except the crest of the dam will
be raised approximately ten feet in elevation from gage height 20 feet to gage height 30 feet.
This increases the reservoir storage to approximately 540 acre-feet. The total project cost is
$2,193,000. This alternative would allow storage of the full conditional decree, and is the
preferred alternative.

Selected Alternative 3 This alternative involves:

1. Reshaping the upstream face of both dams and placement of a compacted clay
liner over the upstream face to inhibit seepage.
2. Excavation of a cutoff trench tied into the clay liner indicated above.

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