Five Entergy utilities took a key step toward membership in a regional transmission organization last week via submission of the executed transmission owner agreement to the Midwest Independent Transmission System Operator or MISO.

The utilities – Entergy Mississippi, Inc., Entergy Texas, Inc., Entergy Louisiana, LLC, Entergy Gulf States Louisiana, L.L.C, and Entergy New Orleans, Inc. – follow Entergy Arkansas, Inc., which submitted its executed TOA to MISO Oct. 31.

The TOA is a contract among the MISO transmission owners that governs a transmission owner's membership in the RTO. The agreement is filed with the Federal Energy Regulatory Commission, and executing the agreement is a key requirement for any transmission owner to join the RTO. By executing the TOA, the Entergy operating companies have agreed to become transmission owning members of MISO, subject to the terms of the agreement.

Friday's action is an important step in the Entergy operating companies' efforts to transfer functional control of their transmission facilities to MISO in December 2013, a step that the utilities' retail regulators have ruled is in the public interest, subject to conditions. The Louisiana Public Service Commission made its ruling in May, followed by Arkansas and Texas regulators in October. In mid-November regulators in Mississippi and New Orleans made their rulings that joining MISO is in the public interest.

Joining MISO is expected to result in savings to the customers of the Entergy operating companies of a projected $1.4 billion in the first decade of MISO membership. Independent studies also forecast significant economic value for electric co-operatives, independent power producers, municipalities and other industry participants, resulting from the move to MISO.

MISO is the oldest and one of the largest regional transmission organizations – a firm that manages congestion on the grid and operates sophisticated markets for the purchase and sale of electricity. The savings projected with MISO are largely attributable to its organized power markets, which allow for a more efficient commitment and dispatch of generating plants, to economies of scale offered by an RTO of MISO's size, and to MISO's transmission cost allocation methodology that equitably allocates the costs of transmission projects to those receiving the benefits from those projects.