24 ‎(3)‎

• Board Meeting Date: 5/21/2008
• Description: ISF Section - Injury with Mitigation - Case No. 5-07CW210; Application of Vail Associates, Inc. and the U.S. Forest Service
• Board Meetings - Doc Type: Memo

Linda J. Bassi April 29, 2008
Page 5
The streamflow would partially recover over the next 14 hours after pumping is
terminated, but there would be some residual impact that would carry over into the next
pumping period. With the proposed 10 hourwell pumping period, the residual impact
would reach 27% of the amount being pumped after 3 days and would continue
throughout the pumping period until pumping is terminated. Aftertermination of pumping,
the streamflow would fully recover to natural conditions within a period 4 days.
100%

90%

80%
~
a~
~ 70%

c
0
~ 60%
a
E
~ 50%
c
'
a
E
~ 40%
a
0
c 30%
m
m
a 20%

10%

0%

0.00 5.00 10.00 15.00 20.00
Days
Figure 3. Daily percentage impact of 10-hour intermittent pumping on streamflow.
The residual impact shown in Figure 3 associated with pumping is primarily dependent
upon the hydraulic conductivity and the distance between the well and the stream. The
residual impact can be reduced by moving the well closer to the stream, but this would
also result in a higher maximum daily impact on streamflow. Under the 10 hours of
pumping per day operational pattern, the impact of the pumping for snowmaking on
streamflows in Two Elk Creek would not exceed 57% of the rate of pumping.
Figure 4 shows the cumulative distribution of estimated flows in Two Elk Creek below
the Tea Cup Bowl Well between November 15th and December 31st based upon the
1964 - 2005 period of record for the Wearyman Creek gage. In dry years (0 to 35%
probability), the average low flow would be about 0.46 cfs in the stream reach
immediately adjacent to the location of the proposed well. In average and wet years, the
average flow during the pumping period would be 0.61 to 0.74 cfs respectively.
AMEC Earth and Environmental, Inc.