WSP07823

• File Number: 8443.200
• Description: Narrows Unit - Mailing Lists Correspondence
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 9/1/1961
• Author: US DoI BoR
• Title: Site Selection Report
• Water Supply Pro - Doc Type: Report/Study

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This has altered the earlier conclusions. Therefore, after
consultation \dth representatives of the Bureau of Mines, costs
were included in the estimate to build mounds having tops 80 feet
in diameter around 5 wells in order that they can remain in operation.
Costs were also included for relocation of about eight miles each
of 4-inch and 6-inch oil and Gas lines and two miles of 8-inch lines.

Outlet Horks. --Separate outlets ,;ould be provided for the Fort
Morgen Canal and for releases to the river. The canal outlet would
have a capacity of 350 cfs and the river outlet, 4,000 cfs for
downstream requirements. Both are minimum capacities 'lith water
levels at the bottom of the conservation pool.

Spilll-1!w.--The spillway would be located on the left abutment.
The maximum combined discharge of the spillway and outlet works
would be about 23,000 cfs. The in1'1ow design flood has a peale flow
of 301,000 cfs and a 20-da.y volume of 1,321,000 acre-feet.

The attached Drawing #553-730-3 shows location of the proposed
Narrovs Reservoir.

'"

Data and Costs--Ueld County Reservoir

i-.

The Weld County dam site is the same as the alternate site mentioned
in the 1951 report under the name "Hardin Site." The name was
changed in order to avoid confusion with the "Hardin Unit" in
Montana. Tbe Weld County site is located about 23 airline miles
upstream from the Narrows dam site and 12 airline miles downstream
from Kersey, Colorado. The reconnaissance cost estimate for this
potential reservoir is $45,459,000 at February 1961 prices, including
$5,450,000 for rights-of-way. Approximately 3,200 acres of irrigated
crop land and 6,700 acres of meadow land would be purchased.

The dam would be in the shape of a flattened letter "z" located about
5 IIliles dO\lllstream from the small town of Hardin, Colorado. It
would have a crest elevation of 4,611 feet and a length of about 5
IIliles. The height above streambed would be about 121 feet. The
freeboard used here was one foot more than at the Narrows site
because the length and shape of the reservoir has potential for
formation of higher waves. The dam would be of earthfill with riprap
on the upstream face. About 15 million cubic yards of embankment
would be required for the dam. Table 5 shows the space allocations
for the various reservoir functions.

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