Western Area Power Administration (WAPA) and the Sacramento Municipal Utility District (SMUD) are studying the potential to build a new 500-kilovolt transmission line. The proposed Colusa-Sutter Transmission Line (CoSu Line) would provide a new link between the California-Oregon Transmission Project (COTP) and SMUD and WAPA's facilities on the east side of the Sacramento Valley. The proposed project would enhance the reliability of the electrical grid in Northern California and increase SMUD's ability to import power from the Pacific Northwest and export power from the Sacramento area.
January 19, 2018: WAPA and SMUD Eliminate Three of the Five Areas under Consideration
During public scoping, which closed in March 2017, WAPA and SMUD shared five study areas under consideration for potential transmission line routes. With development of the Draft Environmental Impact Statement/Environmental Impact Report (EIS/EIR) underway, the agencies have decided to eliminate three of the five study areas. This decision evolved due to comments received during the scoping period and further evaluations that determined their infeasibility to build and/or maintain. The Southern Corridor Study Area was found to be infeasible due to hazards, public safety, and reliability risks posed by the density of agricultural aircraft travel and agricultural airstrips, and the lack of meaningful options to mitigate that risk. The County Road 16 Corridor Study Area and Segment 2 Alternative were found to be infeasible due to technical restrictions on tower heights of the river crossings in proximity to the Sacramento International Airport.
Eliminated Study Areas
- Southern Corridor Study Area: A 27-mile long area that runs west to east from west of Arbuckle to the O'Banion Substation.
- County Road 16 Corridor Study Area: A 27-mile long area that runs west to east from the COTP near Dufour in Yolo County to the existing Elverta Substation in Sacramento County.
- Segment 2 Alternative Study Area: A 9-mile long line that runs 6 miles northwest of the existing Elverta Substation.
Study Areas Remaining under Consideration
- Northern Corridor Study Area: A 44-mile long area that runs west to east from the COTP near Maxwell in Colusa County to the O'Banion Substation in Sutter County. This study area generally follows an existing 230-kV transmission line corridor.
- Segment 1 Alternative: A 9-mile long area that provides a different north-to-south route of the Northern Corridor Study Area to bypass the Sutter Wildlife Refuge.
WAPA and SMUD will continue to study the areas under consideration as they develop the Draft EIS/EIR, which is anticipated for public release in mid-2019. The Draft EIS/EIR will include an analysis of the impacts on environmental resources in the study areas. It will also include a "No Action" alternative that addresses impacts if the CoSu Line is not built. No decisions will be made about selecting a final project alternative or moving forward with construction of the CoSu Line until the Final EIS/EIR is completed, which is anticipated in 2020.
Click on the map above to view the Northern Corridor Study Area and Segment 1 Alternative, and visit the Frequently Asked Questions page for further information about the Draft EIS/EIR and corridor study areas.