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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Facility License Requirement
March 18, 1981, and thereafter:
South Fork
Long Canyon
diversion dam
North Fork
Long Canyon
diversion dam
Middle Fork
interbay
Oxbow
powerhouse
Forecast/Folsom reservoir a
> 1,000,000 acre-feet
< 1,000,000 acre-feet
Forecast/Folsom reservoir a
> 1,000,000 acre-feet
< 1,000,000 acre-feet
76
Release (cfs)
20 May 15–Dec 14
10 Dec 15–May 14
No limitation of total release
Release (cfs)
10 June 1–Oct 14
6 Oct 15–May 31
No limitation of total release
Release (cfs)
Lesser of 5 or natural flow
Lesser of 2.5 or natural
flow
Releases to maintain streamflow of 2 cfs or the natural inflow, whichever
is less, shall be made at all times
Forecast/Folsom reservoir a
> 1,000,000 acre-feet
< 1,000,000 acre-feet
Release (cfs)
Lesser of 23 or natural flow
Lesser of 12 or natural flow
Releases at Oxbow powerhouse shall be 75 cfs at all times as measured
downstream of the confluence with the North Fork of the Middle Fork.
Such releases shall not cause vertical fluctuations (measured in
representative section) greater than 3 feet per hour.
a Forecast/Folsom reservoir = California DWR current year forecast of unimpeded runoff
of the American River to Folsom reservoir.
Controlled flow releases from the Middle Fork interbay dam to the Middle Fork
American River can come from a 20-inch-diameter pipe with a maximum capacity of
23 cfs and a 60-inch-diameter pipe with a maximum capacity of 890 cfs. Controlled flow
releases from the Ralston afterbay dam to the Middle Fork American River can come
from a 30-inch-diameter pipe with a ring-jet valve that has a maximum capacity of 155
cfs at full reservoir volume and a 72-inch-diameter low-level discharge pipe with a
maximum capacity of 1,132 cfs at full reservoir volume. The reach from the base of the
dam to the confluence with the Oxbow powerhouse tailrace is about 0.48-mile long.