About the Project
WAPA, an agency within the U.S. Department of Energy, markets hydroelectric power to customers, including SMUD. SMUD requested transmission service on WAPA's facilities between the COTP and SMUD's facilities. WAPA's existing transmission facilities do not have enough capacity to meet SMUD's need for increased service, so the CoSu Line is being proposed as a solution to meet this need.
The CoSu Line would connect the COTP transmission system in Colusa County, California, to the Central Valley Project (CVP) transmission system south of Yuba City in Sutter County, California, creating a new transmission path and needed capacity. This new connection would:
- improve local and regional energy reliability;
- help the region meet required reductions in greenhouse gas emissions;
- help the region meet required renewable energy content goals;
- ensure the continued safe and reliable operation of the regional transmission system to deliver clean power to homes and businesses in the region;
- assist SMUD in planning for anticipated growth and energy demand; and
- improve the transmission infrastructure network and the Sacramento area's import/export capabilities.
WAPA and SMUD are examining three different study corridors and two segment alternatives as part of the environmental review process. The project features would include new transmission lines and two new substations. WAPA and SMUD initially considered two study corridors and a segment alternative for the CoSu Line in Colusa and Sutter counties. Based on comments received during the public scoping period held from December 2015 to April 2016, the two agencies determined that an additional study area and segment alternative further south of the O'Banion Substation in Sutter County should be considered. The new and originally-proposed study corridor areas are described below.
Proposed Corridor Study Areas
County Road 16 Corridor Study Area (New)
The County Road 16 Corridor Study Area is approximately 27 miles long and would connect to the existing COTP transmission line approximately eight miles west of the community of Dufour in Yolo County, and proceed east towards the existing Elverta Substation in Sacramento County. Two new substations would be built: one adjacent to the existing COTP transmission line northwest of Dufour, and another adjacent to the Elverta Substation.
Segment 2 Alternative Study Area (New)
The Segment 2 Alternative Study Area is approximately nine miles long and six miles northwest of the existing Elverta Substation in Sacramento County and would provide an alternate west-to-east route for the County Road 16 Corridor Study Area. It would extend north in a loop-like fashion, at a location approximately 2.5 miles north of the Sacramento International Airport, and then rejoin the County Road 16 Corridor Study Area as it continues due east to connect to the Elverta Substation. The new segment would be located further away from Sacramento International Airport to provide a greater buffer between the transmission structures and airplane flight paths.
Northern Corridor Study Area
The Northern Corridor Study Area is approximately 44 miles long and would be constructed adjacent to WAPA's existing 230-kV Olinda-O'Banion and Keswick-O'Banion double circuit transmission lines. This new line would connect the existing COTP transmission line near the existing COTP's Maxwell Series Compensation Substation in Maxwell to WAPA's CVP transmission system near the existing WAPA O'Banion Substation in Sutter County. Two new substations would be built - one near the Maxwell Series Compensation Substation and another adjacent to the O'Banion Substation.
Southern Corridor Study Area
The Southern Corridor Study Area is approximately 27 miles long. The new transmission line would connect to the existing COTP transmission line system approximately eight miles northwest of Arbuckle in Colusa County and continue east towards WAPA's existing O'Banion Substation in Sutter County. Two new substations would be built - one adjacent to the existing COTP transmission line northwest of Arbuckle and another adjacent to the O'Banion Substation.
Segment 1 Alternative Study Area
The Segment 1 Alternative Study Area is approximately nine miles long and would provide an alternate north-to-south route for the Northern Corridor Study Area. It would be located immediately west of the existing O'Banion Substation. Instead of following WAPA's existing 230-kV Olinda-O'Banion and Keswick-O'Banion double circuit transmission lines to the O'Banion Substation, this segment would extend south, at a location approximately 30 miles from the Maxwell Series Compensation Substation, and then continue east to connect to the O'Banion Substation. The new segment would be located further away from the Sutter National Wildlife Refuge.
WAPA annually markets and transmits more than 25,000 gigawatt-hours of clean, renewable power from 56 hydroelectric powerplants owned and operated by the Bureau of Reclamation and U.S. Army Corps of Engineers in 15 central and western states, including California. WAPA also owns, operates and maintains a more than 17,000 circuit-mile, high-voltage transmission system in its service territory. It is part of the Department of Energy.
SMUD is the primary distributor of electric power within an area of approximately 900 square miles in Sacramento County and a portion of Placer County, and serves over 624,000 electric customers. SMUD owns and operates an integrated electric system that includes transmission, distribution and generation facilities. SMUD is a member of the Transmission Agency of Northern California, which holds significant entitlements to obtain energy through the COTP. To date, SMUD has used long-term transmission service agreements with WAPA. The CoSu Line project would give SMUD 700 MW of bi-directional transmission capacity with direct access to the COTP for 40 years. It would also allow higher demand levels to be reliably served at lower internal generation requirements, reducing carbon emissions from SMUD's natural gas generation facilities.