Frequently Asked Questions

If built, GCPSP would use wind and solar power to pump water from the Missouri River/Lake Francis Case reservoir into a newly constructed upper reservoir. Then, when needed, the water in the upper reservoir is released and used to operate the hydroelectric generation units to produce energy. GCPSP acts as a large “battery” – and when used in conjunction with wind and solar generation, enables a clean and reliable energy solution for our region.

About the Gregory County Pumped Storage Project

A project of this size and scope will take several years to study and will undergo a robust regulatory review and approval process before moving forward. Your involvement in the process is one way to ensure that we can shape the Gregory County Pumped Storage Project to be mutually beneficial for you, your neighbors and your entire region.

Current Map and Timeline

Cover Letter to the Federal Energy Regulatory Commission

Gregory County Pumped Storage Project Notice of Intent

A Pre-Application Document (PAD) is a requirement of the Federal Energy Regulatory Commission (FERC). The purpose of the PAD is to provide detailed information about a project that is in the applicant's possession or that the applicant can obtain with the exercise of due diligence. The Gregory County Pumped Storage Project's PAD includes detailed descriptions of the proposed facilities, operations, license requirements, environmental resources and impacts, project lands, water resources, fish and aquatic resources, terrestrial and wildlife resources, rare, threatened and endangered species, recreation and land use, cultural resources and socioeconomic resources. It also includes a preliminary list of proposed studies to be conducted during the study period.

On June 28, 2022, Missouri River Energy Services, as agent for Western Minnesota Municipal Power Agency (WMMPA) filed its Notice of Intent to File a License Application (NOI) and the Pre-Application Document (PAD) for the Project with FERC. The filing of the NOI and PAD officially initiates FERC’s licensing process.

Western Minnesota Municipal Power Agency (WMMPA) currently holds a Preliminary Permit with FERC to study the feasibility of constructing GCPSP (FERC No. 14876). The proposed project is located along the Missouri River on Lake Francis Case in south-central South Dakota in Gregory County and includes a transmission line running from the project site approximately 22 miles east in Charles Mix County.

In accordance with FERC's regulations, WMMPA is providing notification of this filing to appropriate federal and state agencies, Native American tribes, local governments, non-governmental organizations, and landowners that may have an interest in the Project. A copy of the PAD can be retrieved by visiting FERC’s eLibrary ( and searching for docket number P-14876, or through this link:

PAD Volume 1

Missouri River Energy Services (MRES) and MidAmerican Energy are working together to study the Gregory County Pumped Storage Project.

MRES is a joint action agency that provides electricity and other energy-related services to 61 municipal electric utilities in four states. We serve 18 municipal electric utilities in Iowa, 25 in Minnesota, 6 in North Dakota and 12 in South Dakota. Each of these members owns and operates its own municipal electric distribution system.

MidAmerican Energy, headquartered in Des Moines, is a rate-regulated utility that provides reliable, affordable and environmentally responsible energy to 1.6 million customers in Iowa, Illinois, South Dakota and Nebraska.

Learn more about MRES and MidAmerican Energy

Do you have questions or comments about Gregory County Pumped Storage Project? We're happy to answer them!

Email or call 605-338-4042 and ask for Joni Livingston. Please keep in mind that our office is open Monday - Friday, 8 a.m. to 4:30 p.m.