The New Orleans City Council voted on Thursday to open an investigation into rolling blackouts instituted by Entergy New Orleans during a cold weather streak last week. The company shut off power to 26,000 customers for just under two hours on Feb. 16, but at a council committee meeting on Tuesday, Entergy officials revealed that the company may have disconnected three times as much power as it had to.

“Unfortunately we’re having to initiate yet another forensic investigation into Entergy New Orleans, really dealing with what I consider irresponsible behavior by the company yet again,” Councilwoman Helena Moreno said on Thursday. “And based on this investigation, we will determine what potential additional action may be taken by the council.”

Moreno noted that even before the revelation that Entergy shut off more power than it had to, the City Council and public already had questions about how the rolling blackouts were implemented. Those questions include why the company shut power to an important Sewerage and Water Board facility and why the company chose certain neighborhoods for blackouts over others. Moreno also said that Entergy New Orleans failed to communicate adequately with the public during the event.

“The public didn’t learn the blackouts were occurring from Entergy New Orleans until two hours after they already started,” Moreno said on Thursday. “Entergy also accidentally cut off power to one of our water intake power sources at the Sewerage and Water Board. And then we were not getting information as to why certain neighborhoods were chosen over others. And to this day we still don’t have those answers. So all of the things I mentioned will be part of this particular investigation.”

The investigation will be conducted by the city’s utility consultants, and Moreno said she expected a report to the council and public in the next 45 days.

The blackouts that occurred last week weren’t typical. Normally, blackouts in New Orleans are the result of equipment failures in the local distribution system, such as downed power lines or utility poles. That’s not what happened last week. Last week’s blackouts were intentionally implemented to avoid a potentially larger, catastrophic collapse.

The cold weather last week caused issues for energy systems across the South, most notably in Texas. The plunging temperatures drove up energy demand as people tried to heat their homes. At the same time, the cold took some generation offline that couldn’t operate in the cold weather. The situation was much more severe in Texas, but Louisiana faced this problem as well. 

In general, when customers try to pull more power from an energy grid than is available, the consequences can be severe, expensive and long lasting. So before that happens, energy systems will attempt to lower energy demand. First, they may ask customers to voluntarily use less power, as Entergy New Orleans did last week. Some energy systems also have “demand response” programs in place that incentivize businesses and residents to shut off power at one of these peak demand times.

But if those voluntary measures fail, utilities like Entergy New Orleans are forced to intentionally cut off power supply to some customers to avoid a larger system failure. That’s what happened on Fat Tuesday when Entergy shut off power to roughly 26,000 customers for just under two hours. 

The decision to disconnect customers wasn’t made by Entergy New Orleans. The company is part of the Midcontinent Independent System Operator, or MISO, which manages a regional energy grid that goes from Louisiana, up through the midwestern US to Manitoba, Canada. Entergy New Orleans is part of MISO South, which includes most of Louisiana, Mississippi and Arkansas as well as a portion of eastern Texas. Much of that area was affected by below average freezing temperatures last week.

MISO made the decision to start disconnecting customers, or “shed load,” on Tuesday. Not only did MISO direct utilities to disconnect customers, it told the utilities exactly how much power they needed to cut. For Entergy New Orleans, that directive was to cut 26 megawatts. But instead, the company disconnected an estimated 81 megawatts of power, more than three times the amount they were mandated to cut. 

“We were very surprised, shocked and really appalled to find out on Tuesday that actually 81 megawatts of power was shut off here in the city of New Orleans, which means that people who should not have been shut off, were,” Moreno said on Thursday. “People were left out in the cold. Businesses lost money. Vulnerable populations did not have power and they didn’t need to be left in the cold.”

Entergy officials said on Tuesday that the cause was likely a problem with an automated program it uses to disconnect power in situations like this, but that the company was still looking into the issue. 

There was only one public comment for the resolution from Justin Schmidt, who suggested the investigation should look into whether Entergy profited by cutting more power than they needed to. The council didn’t respond to the comment. The resolution was passed unanimously.