2023

10-Year
Assessment

Long Range Transmission Plan

The Midcontinent Independent System Operator, in shared responsibility with utilities and states, is leading the Long Range Transmission Planning effort.   

The goal of MISO’s LRTP projects is to ensure reliability while integrating the different operating characteristics of new generation resources and increase the resiliency of the grid in the face of severe weather events.  

The LRTP efforts have been broken into up to four tranches. The first tranche was unanimously approved by the MISO Board of Directors in July 2022. The estimated cost of LRTP Tranche 1 Portfolio is $10.3 billion. 

ATC actively participated in and provided resources and input into the LRTP process and will continue to do so as studies for additional tranches progress. 

LRTP Tranche 1 Portfolio*

There are 18 projects as part of the LRTP Tranche 1 Portfolio; of these 18 projects, ATC has an ownership share in three, including:

MISO Project #Project NameMISO Project DescriptionIn-Service DateTotal Cost Estimate
4Wilmarth - North Rochester - TremvalInstall single circuit 345-kV transmission line between the existing Wilmarth Substation, existing North Rochester Substation and the existing Tremval Substation. June 2028$689,140,000
5Tremval - Eau Claire - Jump RiverInstall single circuit 345-kV transmission line between the existing Tremval Substation, the existing Eau Claire Substation and the existing Jump River Substation. June 2028$504,500,000
6Tremval - Rocky Run - ColumbiaInstall single circuit 345-kV transmission line between the existing Tremval Substation, the existing Rocky Run Substation and the existing Columbia Substation. June 2029$1,049,500,000

The most current information on the Long Range Transmission Plan can be found on MISO’s Long Range Transmission Planning Page.

* Image source: https://cdn.misoenergy.org/20220527%20PAC%20Item%2002a%20MTEP21%20LRTP%20Report%20and%20Feedback%20Review%20Presentation624799.pdf