Pumped storage hydroelectricity allows energy from intermittent renewable sources - such as wind and solar - to be saved for use at times when the wind isn't blowing or the sun isn't shining. Pumped storage hydro allows for larger and longer energy storage than batteries, and it's powered by water - in essence, it's nature's battery.

The Gregory County (South Dakota) area has been studied in the past by the U.S. Army Corps of Engineers as a potential location for an energy storage project and is being studied again now by Missouri River Energy Services (MRES) and our partner, MidAmerican Energy.

What is GCPSP?

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 the use of nearly 100% renewable, carbon-free energy.

About the Gregory County Pumped Storage Project

How can GCPSP benefit the region?

What is the proposed timeline of GCPSP?

Preliminary Timeline of GCPSP

Cover Letter to the Federal Energy Regulatory Commission

Cover Letter to the Federal Energy Regulatory Commission

GCPSP Notice of Intent

Gregory County Pumped Storage Project Notice of Intent

What is the PAD and how do I learn more about it?

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 (https://elibrary.ferc.gov/eLibrary/search) and searching for docket number P-14876, or through this link:

PAD Volume 1

Who is studying GCPSP?

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

How do I contact someone about GCPSP?

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

Email GregoryCountyInfo@mrenergy.com 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.

Back to top