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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Creek diversion dam can come from a 12-inch diameter pipe with a maximum capacity of
2 cfs and a 36-inch-diameter pipe with a maximum capacity of 100 cfs. Controlled
releases from the South Fork Long Canyon Creek diversion dam can come from a 12inch
diameter pipe with a maximum capacity of about 5 cfs and a 36-inch-diameter pipe
with a maximum capacity of 140 cfs. During the winter and spring period, accretion
occurs along the Long Canyon Creek (downstream of North and South Fork diversions)
and in the Duncan Creek bypassed reaches and creates relatively natural shaped
hydrographs in the lower portions of the reaches. The diversions are not operated during
the late summer and fall season (typically August through November) due to low inflow
and minimum instream flow requirements (table 3.3.2-4). Therefore, all inflows to the
diversion pools are passed downstream into the bypassed reaches.
Table 3.3.2-4. Minimum stream maintenance flow requirements (Source: PCWA,
2007b, table Supporting Document B-9, as modified by staff).
Facility License Requirement
Duncan
Creek
diversion dam
French
Meadows
dam
Hell Hole
dam
Forecast/Folsom reservoir a
> 1,000,000 acre-feet
< 1,000,000 acre-feet
Beginning of operations to March 17, 1981:
Forecast/Folsom reservoir a
> 1,000,000 acre-feet
< 1,000,000 acre-feet
75
Release (cfs)
Lesser of 8 or natural flow
Lesser of 4 or natural flow
Release (cfs)
8 at all times
except that total releases shall not
exceed 5,800 acre-feet
4 at all times
except that total releases shall not
exceed 2,900 acre-feet
March 18, 1981, and thereafter: no limitation of total release
Beginning of operations to March 17, 1981:
Forecast/Folsom reservoir a
Release (cfs)
> 1,000,000 acre-feet
20 June 1–July 25
15 July 26–August 5
10 August 6–Oct 31
14 Nov 1–Jan 31
20 Feb 1–May 31
except that total releases shall not
exceed 11,000 acre-feet
< 1,000,000 acre-feet
8 June 1–Dec 1
6 Jan 1–March 25
8 March 26–May 31
except that total releases shall not
exceed 5,500 acre-feet