Draft EIS_072312.pdf - Middle Fork American River Project ...

20120723-4002 FERC PDF (Unofficial) 07/23/2012
of the project during a period when trout fry would have emerged from the gravel and
become relatively mobile. PCWA’s proposed minimum flows would be less than our
recommended minimum flows during planned outages and, during unplanned outages,
would be constant for up to 48 hours regardless of the timing of the outage. Such
releases would not account for changes in flow releases during unplanned outages that
may occur during the summer and could result in redd dewatering during June, when fry
may still be in the gravel. If unplanned outages should occur outside the specified time
frames, the peaking reach minimum flows specified in table 5-2 would apply. The costs
of implementing our recommended minimum flow measure are included in the costs
presented for minimum flows in the previous section, and the increased protection of
aquatic biota in the peaking reach that our recommended flows during powerhouse
outages would provide justify the associated costs.
Implement the Alternative 1 Pulse Flows
Alternative 1 and our recommended pulse flow measure specify a schedule of
pulse flows for each bypassed reach based on water year type (table 5-4), downramping
rates of pulse flows, compliance points, text periods, and reporting requirements. Our
recommended measure is consistent with Forest Service condition no. 23.
Table 5-4. Staff-recommended pulse flow schedule for wet and above normal water
years (Source: Forest Service, 2011a, as modified by staff).
Water Year
Above
Location Wet Normal
Action
May 15 May 7
Release a minimum of 150 cfs or inflow,
whichever is less
Duncan Creek
below Duncan
diversion dam
Middle Fork
American River
below French
Meadows
May 16 May 8 Close diversion completely
May 25 May 10
May 27 May 12
May 30 May 15
June 2 May 18
Release a minimum of 190 cfs or inflow,
whichever is less (can reopen diversion)
Reduce the flow to a minimum of 130 cfs or
inflow, whichever is less
Reduce the flow to a minimum of 90 cfs or
inflow, whichever is less
Reduce the flow to a minimum of 45 cfs or
inflow, whichever is less
June 6 May 22 Release the minimum instream flow requirement
May 15 May 7
Increase flows from the minimum instream flow
release to a minimum of 200 cfs
May 16 May 8 Increase flows to a minimum of 400 cfs
May 24 May 10 Reduce the flow to a minimum of 275 cfs
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