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Performance Report

Water Quality Certification Program

Federal Energy Regulatory Commission (FERC) Project No. 2105
Project Name: Upper North Fork Feather River Hydroelectric Project

Prattville Intakes on Lake Almanor Prattville Intakes on Lake Almanor
Photo provided by State Water Board staff

Applicant: Pacific Gas and Electric Company, Inc. (PG&E)
County: Plumas
License Expiration Date: October 31, 2004
Water Quality Certification Status: Underway
Waterbody: North Fork Feather River
FERC Licensing Process: Traditional Licensing Process

Project Description

The Upper North Fork Feather River Hydroelectric Project (UNFFR Project) is located on the North Fork Feather River in Plumas County. It consists of three reservoirs with dams: Lake Almanor, Butt Valley reservoir and Belden forebay; five powerhouses; tunnels and penstocks connecting the reservoirs to the powerhouses; and transmission, operation and maintenance, and access facilities. The five powerhouses include eight hydroelectric generating units with a total
nameplate capacity of 362.3 megawatts (MW).

Lake Almanor is the upstream-most reservoir on the North Fork Feather River within the UNFFR Project boundary and has the largest usable storage capacity (1,134,016 acre-feet). Lake Almanor is impounded by Canyon dam, an earth-filled structure that is 135 feet high by 1,400 feet wide at its base and 1,250 feet wide at its crest. Canyon dam has an outlet tower with multiple outlets that deliver water to a tunnel capable of releasing up to 2,100 cubic feet per second (cfs) to the North Fork Feather River (Seneca reach). Water is also diverted from Lake Almanor through the Prattville intake, which conveys flow through the 10,899-foot-long Prattville tunnel No. 1A and the 5,568-foot-long Butt Valley penstock to the Butt Valley powerhouse.

Butt Valley reservoir is south of Lake Almanor on Butt Creek, a tributary to the North Fork Feather River. In addition to inflow from the Butt Creek, Butt Valley reservoir receives flow from Lake Almanor through the Butt Valley powerhouse or, in some circumstances, via the bypass valve at the downstream portal of the Prattville tunnel, upstream of Butt Valley powerhouse. Butt Valley reservoir is impounded by Butt Valley dam, an earth-filled structure that is 1,350 feet long by 74 feet high, and 850 feet wide at its base. Butt Valley reservoir has a usable storage capacity of 49,897 acre-feet. Water is diverted from Butt Valley reservoir via the Caribou No. 1 and No. 2 intakes. Flow through the 9,776-foot-long Tunnel No. 2 travels to the 2,222-foot-long Caribou No. 1 penstock to the Caribou No. 1 powerhouse. Flow through the 8,710-foot-long Tunnel No. 2A travels to the 2,322-foot-long Caribou No. 2 penstock to the Caribou No. 2 powerhouse.

Belden forebay is located on the North Fork Feather River downstream of Lake Almanor and below Butt Valley reservoir. In addition to flow from the Seneca reach of the river, Belden forebay receives flow from the Caribou Nos. 1 and No. 2 powerhouses. Belden forebay is impounded by Belden forebay dam, a rock-filled structure that is 500 feet long, 152 feet high, and 630 feet wide. Belden forebay has a usable storage capacity of 2,421 acre-feet. Water is released from Belden forebay into the North Fork Feather River via the Oak Flat powerhouse or is diverted to the Belden powerhouse via the Belden intake and the Belden tunnel and penstock.

In addition to power generation, the UNFFR Project provides a range of recreational facilities, including campgrounds, marinas, and day-use areas. Lake Almanor and Butt Valley Reservoirs provide a variety of recreational opportunities, including contact and non-contact water-based recreation.

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