BOARD01744

• Board Meeting Date: 4/18/1958
• Description: Minutes and Resolution
• Board Meetings - Doc Type: Meeting

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939

Alternate Damsites.--In selecting the most feasible
site for a reservoir to accomplish flood control and conservation
storage for the lower reach of the South Platte River, studies
were made of six different damsites on the South Platte River in
Morgan and Weld Counties, Colorado. Designated in downstream
order, these are the Hardin, Goodrich, Weldona, Narrows, Fort
Morgan, and Old Fort Morgan sites--the only sites found in the
vicinity that could conceivably be considered as alternates for
accomplishing the same purposes as the Narrows Dam.

Hardin Site.--The capacity of a reservoir to the physical
limits o~ the Hardin site would be 423,000 acre-feet at maximum
water surface elevation 4570. In order to maintain service to
the Empire Canal, it would be necessary to have a minimum water
surface elevation of 4548. At this water surface elevation, the
dead storage would be 191,000 acre-feet, leaving only 232,000
acre-feet of active storage. Studies of historical floods indi-
cate a capacity of at least 325,000 acre-feet is necessary to
control historical floods on the South Platte River. To achieve
full flood control benefits, it would be necessary to provide
this 325,000 acre-foot capacity on the South Platte River and
also control Bijou Creek floods by a structure on Bijou Creek,
and it is essential that such capacity be held for storage of
floods. As soon as water has been stored in the reservoir to
reduce ,a flood peak, it is necessary that the water be released
as quickly as the channel can again accommodate it so that the
space may be made available for controlling a subsequent flood.
Unless the operation of flood control space is accomplished in
this manner, no flood control benefits can accrue to the project,
and costs cannot be considered as non-reimbursable. If the
capacity of the Hardin site were used to store water for irriga-
tion, with water held over until such time as it could be used
for that purpose, only minor incidental flood control would
result and nearly all costs of construction would have to be
considered as reimbursable. Under such an arrangement the Hardin
site can produce far less benefits than Narrows and it is clear-
ly less feasible than Narrows. It could not be recommended for
construction.

Goodrich Site.--Foundation conditions are unfavorable at
this site, and the volume of embankment necessary to develop the
required storage would be excessive. Outlets for both the
Jackson Lake Inlet and the Weldona Canal would be required in
the north abutment of the dam. Sediment would enter the
reservoir from Kiowa Creek near the damsite and endanger the em-
bankment. The factors of high cost and the potential danger to
the embankment eliminate this site when it is compared with the
downstream sites of Weldona, Narrows, and Fort Morgan.