lake oroville

FERC Conduit Exemption and Non-Capacity License Amendment Applications

On January 15, 2014, DWR filed the Final Conduit Exemption Applications and the Non-Capacity License Amendment Application with the Federal Energy Regulatory Commission (FERC) to request FERC’s approval to convert the regulatory authorization for the 17 megawatt (MW) Alamo Powerplant (APP) located in Los Angeles County and the 32.4 MW Mojave Siphon Powerplant (MSPP) located in San Bernardino County, into conduit exemptions. This action will not involve any new construction or changes in the operation of the existing generating facilities. Both APP and MSPP are located on the East Branch of the California State Water Project, and are licensed facilities under the South SWP Hydropower FERC Project No. 2426. The Non-Capacity License Amendment Application will request FERC’s approval to: (1) remove APP, MSPP, and the associated lands (located in Kern, Los Angeles and San Bernardino Counties) from the P-2426 license; (2) modify or eliminate the associated maps and facility design drawing exhibits from the P-2426 license; (3) reduce the authorized installed capacity of P-2426; and (4) regulate APP and MSPP under conduit exemptions. The non-capacity license amendment will conform the P-2426 license to such changes. The draft applications were included in the Draft Initial Consultation Documents (ICD) that were previously released for review on June 7, 2013. The final applications and Draft ICDs are available below.

On September 30, 2014, FERC issued an Order (148 FERC ¶ 62,235) approving DWR’s requested license amendment.
A copy of the Order is provided below.

  • Order Amending  License and Revising Annual Charges

The FERC-licensed South SWP Hydropower facilities, also known as Project No. 2426 or P-2426, are located at the southern end of the California Aqueduct south of the Tehachapi Afterbay.

The West Branch, constructed between 1967 and 1982, carries water from the Oso Pumping Plant into Quail Lake, the beginning of the FERC boundary on the West Branch. Water enters the Peace Valley Pipeline which serves as a penstock for the William E. Warne Powerplant. The powerplant outflow is discharged into Pyramid Lake. Water is diverted through the 7.2 mile Angeles Tunnel and into Castaic Powerplant, owned and operated by the Los Angeles Department of Water and Power (LADWP). Water leaving the plant enters the Elderberry Forebay and flows into Castaic Lake, the terminating reservoir of the West Branch.

The East Branch, constructed between 1967 and 1995, carries water from the Tehachapi Afterbay into Alamo Powerplant. From Alamo, water is conveyed through Pearblossom Pumping Plant (not part of the FERC license for P-2426) where it is lifted 540 feet. It then continues its journey south through an open aqueduct into the Mojave Siphon, which conveys the water into the Mojave Siphon Powerplant for power generation before entering Silverwood Lake. Water is then released from the lake, through the San Bernardino Tunnel and plunges more than 1,400 feet through two penstocks into Devil Canyon Powerplant and Afterbays.


The Department of Water Resources (DWR) submitted the original application for a preliminary permit to the Federal Power Commission (now FERC) on November 14, 1963. The Commission issued a preliminary permit on July 16, 1964 allowing planning to begin.

An important amendment to the application was the addition of LADWP as a joint applicant to the West Branch on July 10, 1967.

Original License: FERC issued an order on January 14, 1972 granting issuance of a 50-year license with conditions. The Final Environmental Impact Statement was then issued in June 1976 to comply with the National Environmental Policy Act.

The original license included 28 standard articles (Form L) and 27 other articles specific to the P-2426 license. In addition to these license articles, the original P-2426 license included 58 separate submissions called exhibits. Exhibits include maps, engineering drawings, environmental mitigation plan, recreational plan, and cultural resources management plan.

West Branch

Eaast Branch



Quail Lake Quail Dam and Lake provides regulatory water storage for power generation at Warne Powerplant during peak demand periods. Constructed in 1967, Quail Lake has an operating storage capacity of 7,580 acre-feet. When water is released, it flows from the lake through the Lower Quail Canal into Peace Valley Pipeline.

Pyramid Lake Peace Valley Pipeline serves as the penstock for Warne Powerplant. The pipeline is 5.5 miles long with a diameter of 12 feet and an overall capacity of 1,564 cfs.

Warne Powerplant, located on the Gorman Creek arm of Pyramid Lake, generates power by taking advantage of the 725-foot drop through the Peace Valley Pipeline to Pyramid Lake. This plant, with a maximum rated capacity of 78 megawatts and 2 generators, can generate up to 358 million kilowatt-hours a year.
Castaic Powerplant Pyramid Dam is located on Piru Creek and was constructed between 1969 and 1973. The dam has a height of 400 feet, with a spillway for passing excess inflow into Piru Creek. The spillway consists of a concrete-lined channel controlled by a 40-foot wide by 31-foot high radial gate and a 365-foot long over pour weir with crest set 1 foot above the maximum operating water surface elevation of 2,578 feet.

Pyramid Lake has a maximum capacity of 171,200 acre-feet and serves as an afterbay for Warne Powerplant and forebay for Castaic Powerplant.

Angeles Tunnel Water from Pyramid Lake flows through the 30-foot diameter and 7.2 mile long Angeles Tunnel and generates power at Castaic Powerplant.
Pyramid Lake Castaic Powerplant, designed, built, and operated under a cooperative agreement between DWR and LADWP, is located at the northern end of Castaic Lake's west branch. Regulatory storage for Castaic Powerplant is provided by Pyramid Lake and Elderberry Forebay. Castaic Powerplant has 7 generators with a maximum rated capacity of 1,275 megawatts.

Water from Pyramid Lake flows through Castaic Powerplant into Elderberry Forebay, also operated by LADWP, and it can be pumped back through the plant into Pyramid Lake. This type of operation is called pumped storage. Elderberry Forebay has a maximum storage capacity of 32,480 acre-feet and also provides submergence of the pump-generator units when the lake is at its lowest operating levels. Water from Elderberry Forebay is ultimately delivered to Castaic Lake. Castaic Dam and Lake, the terminal reservoir on the West Branch of the SWP, is located downstream of Elderberry Forebay and is therefore not part of the P-2426 FERC license. The lake has a storage capacity of 323,700 acre-feet and is located about 45 miles northwest of Los Angeles.


Alamo PowerplantOn the East Branch, the FERC Project has two separate reaches. The first is about 0.9 miles in length on both sides of Alamo Powerplant, south of the Tehachapi Afterbay. The second reach begins at the intake to the Mojave Siphon and extends about 9.4 miles to Devil Canyon Afterbay. This reach includes Mojave Siphon Powerplant, Silverwood Lake, the San Bernardino Tunnel and Devil Canyon Powerplant and afterbays.

Alamo Powerplant is located approximately 1.5 miles southeast of the bifurcation of the West and East Branches. It was constructed between 1982 and 1985 and has one generator with a capacity of 18 megawatts.
Mojave Siphon Powerplant Mojave Siphon and Mojave Siphon Powerplant The Mojave Siphon includes 3, 12-foot diameter, pipelines conveying water under the Las Flores Valley floor into the 3 generators of Mojave Siphon Powerplant situated near Cedar Springs Dam. The plant, completed in 1995, has a generating capacity of 29.4 megawatts.
Silverwood Lake formed by the 249-foot tall Cedar Springs Dam, is located at an elevation of 3,355 feet and is the highest reservoir in the SWP. The dam spillway is an ungated, 120 feet-wide, rectangular, lined chute located directly over the outlet works tunnel. The lake was constructed to provide regulatory and emergency storage with a maximum operating capacity of 74,970 acre-feet. The lake serves as an afterbay for the Mojave Siphon Powerplant and a forebay to the Devil Canyon Powerplant. From the south end of the lake, water is discharged into the San Bernardino Tunnel intake.
Devil Canyon Powerplant Devil Canyon Powerplant is a power recovery facility that receives water from Silverwood Lake via the 20,064 feet long, 12.75 feet diameter, San Bernardino Tunnel. Water flows from the tunnel into two parallel penstocks, each over one-mile long and is distributed to the powerplant. The 1,400-foot difference in elevation from Silverwood Lake, gives Devil Canyon the highest hydraulic head among the plants in the SWP. Flows in the Devil Canyon Powerplant discharge in the first afterbay, constructed from 1969 to 1974. The afterbay provides a nominal 50 acre-feet maximum amount of storage, so construction of a second 850 acre-feet afterbay began in 1992 and was completed in 1995. The second afterbay is connected to the first afterbay by a 152-foot wide overflow weir that discharges into a 1,100 feet long and 40 feet wide cross channel, increasing the powerplant's operational flexibility and capacity. Though the FERC project boundary ends at the Devil Canyon facilities, the SWP system continues with the Santa Ana Pipeline conveying water to Lake Perris, the final reservoir on the SWP's East Branch, and the East Branch Extension to eastern Riverside County.