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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
2.2.3 Proposed Project Operation
PCWA proposes several modifications to project operations consistent with its
proposed Instream Flow and Reservoir Minimum Pool measure. The measure would
require:
• higher minimum instream flows in the bypassed reaches and the peaking reach
( downstream of the Oxbow powerhouse);
• spring pulse flows in the bypassed reaches;
• downramping of spill flows from May through July below Hell Hole reservoir
and French Meadows reservoir;
• modified ramping rates at Oxbow powerhouse the peaking reach;
• a cap on flow releases from Oxbow powerhouse (Saturday of Memorial Day
weekend to Labor Day) in dry, critical, and extreme water years;
• consultation with representatives for the two annual trail races to identify and
provide flows suitable for adequate peaking reach trail crossing conditions
(when flows are controllable by the project);
• recreational flow releases in the peaking reach; and
• modified minimum reservoir pool requirements in Hell Hole reservoir and
French Meadows reservoir.
PCWA also proposes to increase the available storage volume in Hell Hole
reservoir by installing a new 6-foot-high Obermeyer spillway gate along the top of the
existing dam crest and increasing the maximum storage elevation of the reservoir.
PCWA states that this increase would allow the reservoir to store additional water during
the spring and summer after the peak of the runoff period which can later be used to
increase annual energy generation. In all but the driest years, PCWA indicates that the
improvement would also allow the project to shift the timing of some generation from the
spring runoff period to the summer peak energy demand period. Although the shift in
timing of the generation would not increase total annual generation, PCWA states that it
would increase the benefit of the project by increasing generation during the peak energy
demand period.
These project modifications are discussed in more detail in the appropriate
resource sections in sections 3 and 4 of this EIS.
2.2.4 Proposed Environmental Measures
PCWA proposes the following mitigation, protection, and enhancement measures.
Geology and Soils
• Implement the Sediment Management Plan.
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