C153833 Feasibility Study

• Contract/PO #: C153833
• Contractor Name: North Poudre Irrigation Company
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: HB 98-1189
• Loan Projects - Doc Type: Feasibility Study

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THE SELECTED PROJECTS

NPIC #6 OUTLET DITCH

Option number two. installing approximately 1300 linear feet of 54-inch diameter reinforced concrete
pipe with a conventional gravel embankment drain is the chosen option for this project. This option
was chosen because of the lower cost and more conventional construction methods.

NPIC RESERVOIR #5 SPILLWAY

Option number two, improving and enlarging the existing spillway to meet State requirements, raising
the low section at the east end of the dam to the same height as the existing dam crest, and purchasing
the necessary easements at both ends of the dam was chosen for this project. This single spillway
option eliminates the need for flood easements with adjacent landowners, as all discharged water will
be contained on NPIC lands.

NPIC RESERVOIR #4 REHABILITATION

Option number two was chosen for this project. This option would retain the dam at approximately the
existing elevation, move the spillway to near the center of the dam, fill the existing spillway, fill low
areas along the south shore, replace the existing outlet works and Parshall flume, install a new toe
drain. reshape the upstream face of the dam, and riprap areas as required, This option was chosen
because it can be accomplished largely upon NPIC lands and the lower reservoir level will allow
retaining the trees around the lake.

INDIAN CREEK RESERVOIR SPILLWAY

Option number three was chosen for this project. This option constructs a 500-foot long spillway to
handle the immediate sub-basin waters at the existing spillway location. lowers the downstream bank of
the Cheyenne Ditch approximately three feet and constructs an earthen berm at the inlet to Indian
Creek Reservoir to handle the extensive upstream sub-basin waters, replaces the outlet works. flattens
the downstream slope of the dam, and provides for toe-drains to control seepage, This option allows
for the diversion of floodwaters before they enter Indian Creek Reservoir, minimizes damage to homes
downstream, and reduces construction on non-NPIC lands south of the reservoir, Additionally. it
makes provisions for correcting the seepage problems that currently exist at the dam toe,

WATER RIGHTS

Table 10 summarizes the history of the water rights and decrees for the North Poudre Reservoirs
affected by this study, The water rights are listed separately in Table 10 for Reservoirs #5 and #6 until
the decrees were combined in 1906, Reservoir #5 had an initial decree of 1,377 acre-feet at a depth of
12 feet above the bottom of the outlet conduit with a Priority Number of 33 and a Priority Date of
1894. Reservoir #6 had an initial decree of 10.216 acre-feet at a depth of 26 feet above the bottom of
the outlet conduit with a Priority Number of 38 and a Priority Date of 1900. Enlargements were made
to both reservoirs, initial decrees were transferred to Reservoir #16 and Halligan Reservoir, and new

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