WAPA » Regions » SN » Environmental review--NEPA

Colusa-Sutter (CoSu) Transmission Line Project, DOE/EIS-0514

​About the Project:

The Colusa-Sutter Transmission Line, or CoSu Line Project, is a proposed 500-kilovolt (kV) transmission line project currently being studied by the Western Area Power Administration (WAPA) and Sacramento Municipal Utility District (SMUD). The CoSu Line Project 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.

This new link between the COTP and the Sacramento Valley 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

Project Features:

WAPA and SMUD will examine 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 updated proposed corridor study area maps can be viewed within the PROJECT DOCUMENTS section below.

Current Status:

WAPA and SMUD are beginning to develop the Draft Environmental Impact Statement/Environmental Impact Report (Draft EIS/EIR) for the CoSu Line. Part of this effort includes requesting temporary right-of-entry to perform studies. Starting in September 2017, WAPA will contact landowners to explain this process and to request temporary right-of-entry for properties in the Northern Corridor and Segment 1 Alternative Study Areas. Visit the Frequently Asked Questions​   page for further information related to right-of-entry.

Earlier this year, WAPA and SMUD held a 60-day scoping period, from January 6 through March 7, 2017, to take comments on the scope of environmental issues to be considered in the proposed CoSu Line environmental documents.  An additional two weeks was scoping comment period extension was given through March 21, 2017, due to extreme weather conditions in the Project area.  The agencies currently reviewed all comments received during this scoping period and have prepared a final Scoping Report​    that includes copies of the public comments from the 2015-2016 scoping period and the 2017 scoping period, and describes the activities conducted during the public scoping period. The Scoping Report will inform the analysis of the Draft Environmental Impact Statement/Environmental Impact Report (EIS/EIR)​. 

​Contact Information and How to Comment:

The scoping period is now closed. However, if you need any additional information regarding the proposed CoSu Line Project, you can contact us though the following methods:

  • Email:

  • Mail:
    Mr. Andrew M. Montaño
    National Environmental Policy Act (NEPA) Document Manager
    Western Area Power Administration, Headquarters
    P.O. Box 281213
    Lakewood, Colorado 80228-8213​

Project Documents:


Project Update
News Release: ​​​WAPA, SMUD release Scoping Report for Proposed Colusa-Sutter Transmission Line Project​
Public Scoping Report    
Public Scoping Meeting Photos​
News Release:  ​​CoSu Public Meetings Help Scope Environmental Review​
News Release:  WAPA, SMUD ​accepting comments on CoSu through March 21​
News Release:  WAPA, SMUD extend Scoping Period of California Transmission Project​
Updated proposed corridor study areas map
Updated Scoping notice newsletter
WAPA's Notice of Additional Public Scoping Meetings​​
News Release:  ​​Colusa, Sutter County communities share insights and concerns on transmission line​
Scoping period extension postcard​
News Release:  Scoping period extended for CoSu Line Environmental Impact Statement​​​​
WAPA's Notice of Scoping Extension
Scoping meetings informational display boards​
CoSu Line Project fact sheet
Scoping comment card
Proposed study areas aerial overview map
Scoping meetings postcard
Scoping notice newsletter
News Release: WAPA, SMUD begin environmental review of California transmission project
WAPA’s Notice of Intent


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Page Last Updated: 12/8/2017 7:56 AM