BOARD00054

• Board Meeting Date: 1/12/1998
• Description: ISF Section - Acceptance of Injury with Mitigation
• Board Meetings - Doc Type: Memo

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development of Bear Creek and development 9f Bridal Veil.
Expansion of the existing Mill and Cornet Creek treatment plants
was not preferred due to limited physical water availability during
the late summer and winter period. Also, these alternatives would
cause additional direct depletion to the San Miguel River.
Similarly, the alternative of using high-capacity wells in the San
Miguel River alluvium would also directly deplete area streamflows.
In addition, the development of high-capacity wells, including the
use of the existing Town wells, was not favored due to water
quality concerns associated with historic mining activity. As
previously discussed, Bear Creek was found to be less attractive
due to high costs and impacts on the instream flows in Bear Creek
and in the San Miguel River below its confluence with Bear Creek.
In the end, development of Bridal Veil surfaced as the alternative
which provides the most protection to the instream flows.

Expansion of the Mill Creek treatment plant was carefully
evaluated because the treatment plant was specifically designed to
allow expansion of an additional O.S MGD (0.75 cfs) of treatment
capacity. However; the study recommended that the Mill Creek Plant
not be developed due to limited physical waeer supplies and water
quality constraints. During dry years Mill Creek stream flows at
the plant were projected to vary from 1.3 cfs to 1.5 cfs over the
period of December through March. This flow rate equals or is
slightly less than the plant's existing 1 MGD treatment capacity.
Consequently, the study concluded, the Mill Creek expansion would
not provide necessary water supplies during dry periods.

The study also conl:luded that the Mill Creek water supply
is limited due to water quality constraints. Treatment capacity is
frequently reduced during spring runoff and during summer
thunderstorms by high turbidity. During these periods the
treatment plant capacity is frequently reduced by as much as 2St to
50%. Finally, expansion of the Mill Creek plant would increase the
Town's reliance on direct stream diversions. Additional diversions
would be under the Town's senior municipal rights and therefore,
the expansion of the Mill Creek plant would have a direct impact on
the instream flow rights downstream of Mill Creek. '

The Town's representatives discussed these studies_wi~h
SMVC representatives at the January 9 meeting.

The Town has carefully evaluated all feasible
alternatives to meet its future water supply needs and has found no
reasonable alternative that would be more protective of the
instream flows. The ability to use storage releases instead of
direct flow dive:;:-sions during periods of critically low flow
clearly ma~es the development of Bridal Veil the best alternative
for protection of the instream flows of the San Miguel River and
its tributaries.

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