By Mark Hoffman, Chief Operations Officer at East River Electric
East River Electric, Central Electric’s wholesale power provider, is making transmission improvements and additions across Central’s service area to benefit member-owners. These projects span Davison, Hanson and Miner counties and continue to Lake and McCook counties, served by Sioux Valley Energy and Southeastern Electric. The planned improvements support the new High Plains Processing plant (a multi-seed crush facility under development south of Mitchell), accommodate regional load growth and modernize a vintage transmission system dating back to the 1950s — all aimed at improving reliability.
The upgrades begin at the Western Area Power Administration (WAPA) Mount Vernon substation, where an additional circuit breaker was added. Before the project, East River served five substations across 56 miles of line exposure. A disturbance in any of the five substations or on the 56 miles of transmission line would result in a blink or outage for everyone served by the Mount Vernon, Mitchell, Plano, Farmer and Emery substations. This new breaker enables East River to sectionalize the system, dividing it into manageable sections during outages and maintenance, reducing the impact to members, and balancing the substation and line exposure out of the WAPA Mount Vernon Substation.
From the WAPA Mount Vernon substation, East River rebuilt 13 miles of line heading east to the Letcher tap, which feeds north to the Loomis, Letcher and Woonsocket areas. This line was rebuilt with a double circuit, one line serving the ethanol plant near Loomis and a second line continuing towards Mitchell. These two lines go around Central’s headquarters building west of Mitchell. The section of line going east of this was rebuilt in 2014.
The line continues east to the Mitchell substation, built in 1952. This substation is being rebuilt adjacent to the High Plains Processing Plant. It will be expanded to serve both the new plant and members currently served by the existing 1952 substation, which will then be retired. The section of line from the Mitchell substation east was also rebuilt in 2014.
Further east, East River plans to build the new Hanson County Substation, where 115 kilovolt (kV) transmission lines from the WAPA Letcher substation will step down to 69 kV. As part of this work, East River will rebuild 13.5 miles of line going west from the Hanson County substation, and three additional miles going east, replacing lines dating back to 1952.
Going north, 25 miles of new 115 kV transmission line will be built to connect to the WAPA Letcher substation, where East River will add an additional circuit breaker providing a 115 kV source to the Hanson County substation. From there, the system continues northeast to the new Miner County switching station. This station provides a location where the lines are sectionalized, providing greater reliability to members by reducing the impact of outages. From that station, East River rebuilt five miles west toward Fedora Substation, half a mile east for Roswell Substation and a third line that stretches 41 miles east to the edge of Madison in Lake County.
In addition to these efforts, East River will also modify and upgrade the Fedora, Howard, Howard City and Plano substations. A new substation addition in Lake County will help expand the 115 kV system in the area and tie into the VT Hanlon substation east of Montrose. Breaker work at the VT Hanlon substation will connect WAPA’s 230 kV system between Letcher and VT Hanlon with East River’s system between the two substations.
In total, the projects in Central Electric’s area include 76 miles of rebuilt transmission line, 25 miles of new transmission line, two new transmission substations, three transmission substation circuit breaker additions, a distribution substation rebuild and modifications to four distribution substations. Work began in 2024 and is scheduled for completion by mid-2026. These improvements will enhance power quality and reliability for Central Electric members and the greater East River Electric system.