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.
The CoSu Line project features include a new transmission line and two new substations. WAPA and SMUD are currently examining one corridor study area and a segment alternative as part of the environmental review process. The study corridor area and segment alternative study area are described below.
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.
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 and SMUD are examining alternatives for the transmission line routes and substation locations within the Northern Corridor and Segment 1 Alternative Study Areas only, and conducting studies in this area. The Northern Corridor Study Area and Segment 1 Alternative Study Area encompass larger sections of land than will ultimately be needed for the CoSu Line. The transmission line route and substations to be built will occupy a much smaller portion of land. WAPA and SMUD expect the final project right-of-way (ROW) to be approximately 200- to 250-feet wide for the transmission easement and up to 75 acres for the substations.
Elverta Substation Upgrades (update April 4, 2018)
At the initiation of the scoping period for the CoSu Line, SMUD anticipated that the Elverta Substation would require an upgrade of electrical infrastructure and expansion of the facility footprint to support improved electric reliability for the Sacramento region. Further reviews indicate that upgrades to the Elverta Substation will not be needed to support the CoSu Line.
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.