Before the FERC Application for New License for the Annex Creek ...

3.0 SALMON CREEK COMPONENT
Sa 1 mon Creek Reservo; r is located about 3 mi 1 es north of downtown
Juneau. The Sa 1 mon Creek dra; nage bas in has a tota 1 area of approx; ma te 1 y
11.0 square miles above the mouth. Salmon Creek originates about 3.5 air
miles northeast of Juneau and flows generally westward for approximately
5 river miles before emptying into Gastineau Channel, approximately 3 miles
northwest of downtown Juneau. The drainage area intercepted by Salmon Creek
Reservoir is estimated to be approximately 5.2 square miles. The surface area
of the reservoir is approximately 165 acres at maximum pool (E1 1140).
An arbitrary elevation datum was used for the Salmon Creek Dam and
Upper Powerhouse when they were constructed. This arbitrary datum is
26.29 feet below Mean Lower Low Water (MLLW) and fixes the dam spillway crest
at E1 1172. Throughout thi s exhi bi t thi s datum wi 11 be referred to as the
Upper Salmon Creek Datum (USCD).
The Lower Penstock and Lower Powerhouse used an elevation datum
4.79 feet blow MLLW. Thi s arbi trary datum wi 11 be referred to as the Lower
Salmon Creek Datum (LSCD).
The drainage basin varies in elevation from sea level to 4935 feet
at Observation Peak. In contrast to the nearby Gold Creek and Lemon Creek
basins, only a sma.11 portion of Salmon Creek basin is covered by glaciers.
3.1 PROJECT OPERATION - PROCEDURES AND CONSTRAINTS
The Applicant proposes to continue operation of the Salmon Creek
Component at a reduced maximum, providing maximum power generation during the
peak winter load months of December through Apri 1. The Salmon Creek Upper
Powerhouse wi 11 be operated on 1 y as a reserve fac i 1 i ty for the Lower Powerhouse
and as necessary to maintain minimum flows in Salmon Creek. As
described in Exhibit E (2.2.4), streamflow is to be maintained at a level of
1 .4 feet as measured on the staff gage near the fi sh hatchery fac i 1 i ty. The
Salmon Creek Lower Powerhouse is remotely operated. All control alarms and
indications are also te1emetered to the Thane Operations Center. The plant
factor of the Sa 1 mon Creek fac 11 i ty is es ti ma ted to be 54%, based on an
installed capacity of 10,500 kVA and average annual energy generation.
The Sa 1 mon Creek power fac i 1 i ty i s operated wi th in the fo 11 owi ng
constraints:
o Maximum permissible reservoir elevation of 1140 feet (USCD), as
ordered by the Federal Energy Regulatory Commission on September
28, 1984. Paragraph (B)(b) of the license for the Salmon Creek
Project was revised on that date.
o Maximum penstock release flow of 4.64 cfs for water supply as
agreed with the City and Borough of Juneau. Release is made
B-5