Mariposa Energy Project

Docket Number:

09-AFC-03 (Application For Certification)
09-AFC-03C (Compliance Proceeding)

Project Status: Licensed; In Compliance Phase.
Operational: October 2011

The California Energy Commission approved this project's Application For Certification on May 18, 2011. The Commission monitors the power plant's construction, operation and eventual decommissioning through a compliance proceeding.

Key Dates

  • 6/15/2009 - Application for Certification (AFC) filed
  • 8/26/2009 - Commission accepts AFC as "data adequate."
  • 11/8/2010 - Commission staff releases Preliminary Staff Analysis.
  • 12/16/2010 - Commission staff releases Supplemental Staff Assessment.
  • 11/08/2010 - Commission staff releases Staff Analysis.
  • 4/13/2011 - Committee releases Presiding Member's Proposed Decision.
  • 5/18/2011 - Commission approves Application for Certification.
  • 10/2011 - Power plant on line and producing power.


artist depiction of power plant project from the airMariposa Energy, LLC (Mariposa Energy) filed an Application for Certification (AFC) on June 15, 2009 for the Mariposa Energy Project (MEP). This proposed project would have a nominal capacity of 200 megawatts (MW). The facility would be a simple-cycle generating facility consisting of four GE LM6000 PC-Sprint natural gas fired combustion turbine generators, and associated equipment. Linear facilities would include a new 580 feet natural gas pipeline and a new 1.8 mile water connection with the Byron Bethany Irrigation District.

The proposed project site is in northeastern Alameda County, approximately 7 miles northwest of Tracy, 7 miles east of Livermore, 6 miles south of Byron, and approximately 2.5 miles west of the community of Mountain House. The facility would be located southeast of the intersection of Bruns Road and Kelso Road on a 10-acre portion of a 158-acre parcel (known as the Lee Property) immediately south of the Pacific Gas and Electric Company (PG&E) Bethany Compressor Station and 230-kilovolt (kV) Kelso Substation.

Energy Commission Facility Certification Process

The California Energy Commission is the lead agency (for licensing thermal power plants 50 megawatts and larger) under the California Environmental Quality Act (CEQA) and has a certified regulatory program under CEQA. Under its certified program, the Energy Commission is exempt from having to prepare an environmental impact report. Its certified program, however, does require environmental analysis of the project, including an analysis of alternatives and mitigation measures to minimize any significant adverse effect the project may have on the environment.

For Questions About This Siting Case Contact:

Anwar Ali
Project Manager
Siting, Transmission and Environmental Protection (STEP) Division
California Energy Commission
1516 Ninth Street, MS-15
Sacramento, CA 95814
Phone: 916-654-5020

For Questions About Participation In Siting Cases Contact:

Public Adviser
California Energy Commission
1516 Ninth Street, MS-12 Sacramento, CA 95814
Phone: 916-654-4489
Toll-Free in California: 1-800-822-6228

News Media Please Contact:

Media & Public Communications Office
Phone: 916-654-4989

Compliance Proceeding

Original Proceeding



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