BOARD02052

• Board Meeting Date: 8/15/1995
• Description: Notice of Board Meeting
• Board Meetings - Doc Type: Meeting

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.. Water Supply and Storage Company
.. Page 5

cutthroat and brook trout are present in some of the deepest pools in the
stream channel. Fishing in all project-affected waters is insignificant at the
present time. This condition would not be expected to change over the period
of analysis without the project.

Under project conditions, the enlarged Long Draw'Reservoir would have a
surface area of about 340 acres and have a capacity of 11,000 acre-feet when
full. The reservoir would stan fIlling in May and usually reach its high point
about the middle of July. Water would be drawn from the reservoir as
needed until the end of the irrigation season in September or October. The
outlet gates would then be closed and remain closed through the winter months.
The winter inflow to the reservoir is expected to be mirwr; thus, the reservoir
would remain near its low point through the winter months. Without a
minimum pool and with poor access fIshing would continue to be insignificant.
Long Draw Creek downstream of the reservoir would remain much the same
as it is under the present operation. (Italics inserted by writer.)

Dam safety was the overall driving force in the fInal design of the Long Draw Dam. This
was focused on the spillway, outlet works and the embankment as integral and balanced
components taking into consideration the remoteness, inaccessibility and lack of
superintendence for long periods of time during the winter.

For instance, it was concluded that closing the gates during the winter would provide a static
winter condition without having to be concerned about the problem of maiJJtllinine small
flows. These small flows cause gate wear and tear due to high pressure "spurting" orifice
flow which leads to cavitation. Without flowing water and with the dam "buttoned down"
for the winter, there would .be little to worry about.

Closing the gates during the winter would also alleviate concerns about unpredictable ice
buildup against the inlet screens, in the outlet conduit, and in the downstream open channel.
chute and flip-bucket. The chute and flip-bucket would also be subject to dense snowpacK
plugging from wind deposited snow. Because of these hazards, the chute was intentionally
left open to allow for easy'visual inspection of the outlet works conduit by sighting.

The downstream "plunge pool" and parshall flume water measuring stations were designed
and constructed without provisions being made for icing of a winter flow. The parshall
flume, for instance, would be subject to ice damage with winter release, and the ice
formation and snowpack would cause plugging of the flume and water backup with
additional icing tendencies.

The Long Draw Dam has undergone numerous inspections over the last 20 years and was
found to be free of dam safety concerns. This is a result of the careful and thoughtful