PUB00108

• Year: 1986
• Title: St. Vrain Basin Reconnaissance Study
• CWCB Section: Administration
• Author: Colorado Water Resources and Power Development Authority
• Description: Extensive study for future study and development toward meeting the water-related needs of residents with the St. Vrain Basin
• Publications - Doc Type: Brochure

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Page 7

supply reservoir, together with purchase of C-BT Project shares and implemen-
tation of non-structural measures. Estimated costs of agricultural yield from
structural measures are $360/ac-ft for Plan 3C, $480/ac-ft for Plan 2A,
$590/ac-ft for Plan 3A and $700/ac-ft for Plan 3B.

b. Selection of Preferred Plan

The Study has identified and evaluated a number of plan elements
which have significant potential to serve the water resources management needs
of the Study Area. However, of the six alternative plans evaluated, none
appears to be clearly optimal or suitable in total for detailed feasibility
studies and eventual implementation, since significant uncertainties remain,
particularly in regard to the technical and environmental feasibi lity of stor-
age sites. Engineering and geotechnical investigations, including drilling,
are needed to further evaluate the major dam and reservoi r si tes to reduce
uncertainties, and more thorough analysis is needed of the more promising
non-structural measures.

7. The Coffintop, Geer Canyon, and Boulder Creek Proiects

The reconnaissance-level work performed in this Study indicates
that development of the Coffintop Project would be more costly for municipal
for water supply purposes than alternative storage projects, including reser-
voirs at the Little Thompson, Smithy Mountain, and North Sheep Mountain
sites. Major social concerns also exist concerning development of the Coffin-
top Project. Since feasibi I i ty-Ievel work has previously been performed at
this site by others, it is concluded that no further study should be made of
the Coffintop Project except if further study of projects at the Little
Thompson, Smithy Mountain, and North Sheep Mountain sites should all indicate
their respective project costs are significantly higher than the estimated
costs developed in this Study. The Geer Canyon Project on Left Hand Creek
would be costly and only I imited potential exists on this stream for develop-
ment of new water supplies. In addition, a large number of residences are
located in close proximity downstream of the dam site which would result in a
social concern. The Geer Canyon site was not included in any of the plans
formulated by the Study.

Sites on Boulder Creek were reviewed at a reconnaissance level and
it is concluded that because of potential costs and the over-appropriated
situation of Boulder Creek water rights, that development of a storage project
on Boulder Creek to serve the St. Vrain Basin would not be feasible.

E. Recommendations

Because there does not appear to be one clearly superior plan from
among the six plans formulated and evaluated in the Study, none of the plans
in total are recommended for feasibility studies. More study of certain plan
elements is considered necessary prior to compiling a definite recommended
plan for which full feasibi I ity studies would then be undertaken. Decisions
regarding implementation would be based on results of the feasibility studies.