The LPSC Staff, Entergy Louisiana (ELL) and MISO have each released ‘After-Action Reports’ that take a deep-dive and investigate what caused the May 25, 2025 blackout, and to provide recommendations to avoid a similar type of blackout from happening again.
Below is a high-level summary of the reports.
1. Too many power plants were offline (some planned, some unplanned) and 50% of the generation in our area was unavailable.
ELL’s River Bend nuclear power plant was subject to an unplanned outage on May 21. The outage was a result of a leak in the reactor’s cooling system. The leak was repaired and River Bend returned to service on May 26.
ELL’s Little Gypsy 3 gas power plant also suffered an unplanned outage. The outage began on April 1 and was due to turbine vibration issues.
Washington Parish Energy Center Unit 2 gas power plant experienced an unplanned outage in the early afternoon of May 25. It returned to service and reached full output about fifteen minutes after the May 25 outage and load shed event began. Because of this unit’s location relative to the transmission constraint, its outage did not contribute to the blackout.
Several non-Entergy generators in southeast and south-central Louisiana also were experiencing unplanned outages on May 25.
The map below shows four load pockets (sort of like a traffic jam) in Entergy’s planning area. The two load pockets in green are discussed in the After-Action Reports.
2. A major transmission line was out of service. That line usually moves power from southwest Louisiana to southeast Louisiana.
The Nelson–Richard 500kV transmission line was unable to operate on May 25. This was the result of damage from a tornado in March. This line moves power from southwest Louisiana to southeast Louisiana. The line was fully repaired and returned to service on May 27, 2025.
According to Entergy no other planned or unplanned transmission outages contributed to the blackout.
3. Short timelines to act, limited communication, and a transmission outage designation unique to MISO left operators and utilities with limited time to manage the situation.
MISO is the only transmission operator with a temporary Interconnection Reliability Operating Limit (IROL) designation. A temporary IROL is a specific, urgent reliability designation used by MISO when a transmission line or system condition is temporarily limited, and exceeding that limit could lead to a widespread power outage, system instability, or cascading outages and physical grid damage. The unique temporary IROL designation results in a very limited amount of time to communicate between grid-operators, utilities and regulators.
The below recommendations are a high level summary of the three after-action reports prepared by Entergy Louisiana, MISO, and Public Service Commission staff/advisors (LPSC Staff Report, Entergy Louisiana After-Action Report, MISO After-Action Report).
Keep reading for more specifics on these recommendations.
Imagine you’re driving a car on a busy highway. Sometimes, there are stretches where traffic slows down or even comes to a halt, like when your in or near a city, while other parts of the road are clear and you can speed up, often in more rural areas.
Similarly, in the world of energy, there are areas of the power grid where electricity demand is consistently very high — like in residential neighborhoods during hot summer days when everyone is running their air conditioners, or there’s high industrial electricity demand. If there aren’t enough transmission lines to connect these areas to power generation, aka power plants, that is often located farther away from population centers, it creates an imbalance in supply and demand that threatens access to power when needed. These areas are called load pockets, and they act like the congested parts of the highway.
A load pocket is like a traffic jam on the energy highway with not enough lanes, and its rush hour. It’s a specific area within the power grid where the electricity demand is consistently high and it can be challenging to supply that demand without building more transmission lines or a expensive new power plant.
Many south Louisiana electricity consumers are located within load pockets. Learn more about load pocket’s in our previous blog, Load Pockets and Congestion Costs Impacting Your Pocket.
Improve communications between local utilities, MISO, regulators, and the public during a transmission emergency.
Regulators in Louisiana, Arkansas, Mississippi and Texas and MISO must work together to develop regional plans for a grid that benefits everyone.
Our regulators must push utilities to fix load pockets by working regionally to expand transmission capacity and improve connections within our state and with our neighbors so that power can get from where it’s generated to where it’s needed. Regulators should also work with utilities to deploy programs that reduce energy demand by, for instance, incentivizing using less power at specific times of high demand.
Regulators must fix the Amite South and Downstream of Gypsy (DSG) load pockets by building more transmission and planning in coordination with regional neighbors.
MISO will begin a Load Pocket Risk Assessment in 2026. This assessment will examine the needs and solutions to potentially fix the load pocket issues in southeast Louisiana, where the May 25 blackout happened.
