Welcome To The Mammoth Geothermal Complex Website

The Mammoth Geothermal Complex is located in the Eastern Sierra Nevada mountain range in California. It features three power plants that generate 29 MW, enough electricity for 22,000 homes. Ormat, the world leader in the geothermal market, owns the facility.

The first power plant, G1 (MP1), started operations in 1984 and G2 (MPII) and G-3 (PLES-1) came online in 1990. All the power plants use air-cooled binary technology. The G1 power plant was the first binary power plant in California and the world’s first air-cooled geothermal power plant to incorporate two closed-loop systems. In 2005, the wellfield was expanded into what is known as Basalt Canyon west of the power plants. Two production wells were drilled and connected to the existing power plants. Ormat repowered the G1 power plant in 2014 replacing 30-year old equipment with Ormat-manufactured OECs to improve its efficiency.

Recent Developments

News: BLM approved the Groundwater Monitoring and Response Plan on Jan 13, 2017. read more here

The geothermal industry responds to MCWD’s uninformed opinion here

See an engaging story about the dispute between Ormat and MCWD here

June 2015: The Mono County Superior Court ruled in favor of the project. Here is a summary and full report of the ruling

August 2015: The Internal Board of Land Appeals issued an order rejecting MCWD’s appeal click here

Read Ormat’s letter to MCWD here

Review Ormat’s CD IV Monitoring and Response Plan here

For more information on the dispute click here 

To learn more about the CD IV project visit the project page

Casa Diablo IV Project Highlights

Ormat has worked extensively to ensure our ongoing operations at the Mammoth Pacific are safe to the community and the environment.  Working in concert with regulatory agencies, we meet or exceed all requirements with the existing power plants as well as with our plans for future expansion projects. 
The Casa Diablo IV expansion is a perfect example of our commitment to prudent development.  We have collected 30 years of monitoring data that has been analyzed and studied by many experts.  The proposed area that will provide geothermal fluid to the CD IV expansion was developed in 2006 with two production wells that are already connected to the existing plants. Data has been collected from these two wells for over nine years. These wells have shown no adverse affects. As is the current practice, all geothermal fluids are injected back into the geothermal reservoir, this is critical to the sustainability of the resource.  Injection is  planned for CD IV in the Basalt Canyon field and was analyzed in the EIR/EIS  for both resource and surface impacts. 
On June 26, 2015 the Mono County Superior Court denied the appeal by the Mammoth Community Water District.  In addition, on August 31, 2015, the  Interior Board of Land Appeals also denied an appeal by MCWD. Despite many  false claims made by MCWD, Ormat continues to believe this new project would  not impact the water supply for the Town of Mammoth Lakes. We uphold our commitment to working in concert with the regulatory agencies and the MCWD to ensure there are no adverse affects as we provide clean, renewable, reliable electricity to Mono County and beyond. 
For more information on the dispute click here.