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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Table 3.3.2-10. Proposed and Alternative 1 up- and downramping rates proposed for
March through October at Oxbow powerhouse. Ramping rates would
be based on the flow present in the Middle Fork American River near
USGS Gage No. 11433300 (Source: PCWA 2011a and 2011b, as
modified by staff).
Gage Flow (cfs)
Upramping Downramping
Maximum Flow
Change (cfs/hour) Gage Flow (cfs)
111
Maximum Flow
Change (cfs/hour)
500–800 400
>400–750 600 >800–1,300 550
>750 750 >1,300 750
PCWA proposes ramping rates in the peaking reach as specified in table 3.3.2-10.
Compliance in years 1 and 2 after license issuance would be based on flow measured in
the Middle Fork American River near Foresthill (USGS gage no. 11433300). In year 3
after license issuance or as soon as the new Oxbow powerhouse penstock gage is
operational, ramping rates would be measured at the new Oxbow powerhouse penstock
gage and the Middle Fork American River near Foresthill (USGS gage no. 11433300).
During the months of November through February, PCWA would make a good faith
effort to regulate Oxbow powerhouse flow releases in the peaking reach. This would
include, to the degree possible, scheduling Oxbow powerhouse generation to moderate
peaking in the Middle Fork American River using available active Ralston afterbay
storage. PCWA also proposes to impose a 900 cfs upper limit on Oxbow powerhouse
releases in the summer of drier water years.
Alternative 1 includes the ramping rates specified in Forest Service condition no.
24. Alternative 1 is similar to PCWA’s proposal for ramping, except for an additional
clause indicating that during the first two events when down ramp of spill flows occur at
Hell Hole and French Meadow reservoirs, PCWA would test its ability to manage spill
flow to provide the specified ramping rates. Deviations from the criteria during these
tests would not be considered violations but would be reported to the Forest Service
California Fish and Game, and the Water Board within 30 days of the occurrence. After
each spill event, a testing report would be submitted to the Forest Service, California Fish
and Game, and the Water Board, with any recommendations for a modified downramping
rate. After agency approval of any modified ramping rate, PCWA would submit the
modified downramping schedule to the Commission.