WSP06225

• File Number: 8059
• Description: Section D General Studies-State Water Plan
• State: CO
• Date: 1/1/3000
• Author: CorpsofEngineers
• Title: State Water Plan Potential Projects-Information on the Potential Plans of Improvement in the Sand and Toll Gate Creeks Basin-An Extraction from the Corps of Engineers Interim Report
• Water Supply Pro - Doc Type: Report/Study

fUnction for the Sand Creek reservoir was constrained by the
limited water yield of the Sand Creek basin and the cost of
acquiring additional recreation lands. The incremental benefits
of providing additional recreational lands would not justify
the costs of acquiring such lands. The water yield of the
basin is so limited that in order to l\IB.intain a permanent pool
for recreation purposes, it would be necessary to import water
into the basin. Although the probability of importing water
is small, it is a real possibility for the future. In light
of the above considerations, the project's recreation fUnction
was formulated without permanent storage in the reservoir. The
recreation plan was developed to use the project lands most
effectively and efficiently. Provisions were made in the
recreational development plan to incorporate a permanent pool
if a source of water is found.

c. In order to provide a ballis for selecting a size for
the Sand Creek reservoir, studies were conducted to determine
the economic optimum scale of development. Several levels of
flood control storage were analyzed, including storage of the
l-percent, standard project, and probsble maximum flOOds. The
costs and flood control benefits attributable to each level were
developed and compared. The results of this analysis indicate
that a reservoir capable of storing the standard project flood
below the spillway crest would maximize net tangible benefits.
In view of such intangible considerations as providing protec-
tion against the potential loss of lives, the protection of the
general health and welfare of the Denver area, the provision of
an adequate degree of flood control for Sand Creek basin resi-
dents, and the prevention of disruptions of community activi-
ties, the maximum feasible level of flood control storage in the
Sand Creek reservoir was adopted. The reservoir, therefore, was
sized to tsle 1'UlI advantage of the site capacity by perching
the spillway 17 feet above the standard project flood.

d. Toll Gate Creek dam and reservoir. To provide for the
laO-year accumulation of sediment, an allowance of 2,000 acre-
feet was made in the Toll Gate Creek reservoir. As in the case
of the Sand Creek reservoir, the water yield from the basin
upstream from the Toll Gate Creek reservoir is insufficient to
support permanent storage for recreation. The recreation plan
for the Toll Gate Creek reservoir, therefore, was formulated to
develop the project lands for park-type facilities but without
a lake for recreation. Care was taken in developing the plan,
however, to insure that a permanent recreation pool could be
added in the future if a source of water is found.

e, Studies of various levels of flood control storage in
the Toll Gate Creek reservoir were conducted in the same manner

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