LANSING, Mich. (AP) - Michigan regulators on Wednesday ordered an investigation into lengthy power outages stemming from a pre-Christmas ice storm that knocked out service to 660,000 customers statewide, the vast majority served by large utilities Consumers Energy and DTE Energy.
Noting that utilities can recoup costs from tree trimming and other maintenance, the state Public Service Commission said it wants to know of any evidence that the two companies' failure to keep up their systems contributed to the outages.
Other questions include how the utilities deployed line crews; their preparation for the storm; if changes can be made to prevent future outages of such a magnitude; and whether accurate information was relayed to customers. Regulators also asked for more information on whether downed power lines were addressed in a timely manner.
Scores of tree branches broke and fell from the weight of ice during the storm.
Consumers had 416,000 customers and DTE 210,000 customers without electricity, some for a week or more. That's 13 percent of all power customers in Michigan.
The Lansing Board of Water & Light, a municipal utility not regulated by the PSC, had 40,000 customers without power -- some for up to 10 days.
"We're doing (the probe) because of the magnitude of the number of customers that were out and for that length of time," PSC Chairman John Quackenbush told reporters after the panel voted 3-0 to investigate.
Customers without power at least five days may qualify for a $25 credit.
Quackenbush said the commission typically orders probes into outages after a major storm every four or five years.
In 2009, the panel told Consumers and DTE to make changes after residents were frustrated by long power outages caused by storms in 2008. The companies were directed to better notify customers of the $25 credit and to consult with state and local officials about addressing the problem of trees killed by the emerald ash borer falling onto power lines.
Tree trimming will be looked at this time around, too.
"That's what we want to find out: Was it a factor that contributed?" Quackenbush said.
The utilities are to file reports addressing the commission's questions no later than Feb. 7. The public can comment on the reports until Feb. 21. Commission staff will make recommendations, if needed, in March -- after which the panel could order specific actions by the utilities.
Consumers spokesman Dan Bishop welcomed the review and said the company is proud of its work to restore power to the 23 percent of its customers affected by "this catastrophic event." Customers, emergency operations officials and others are finding Consumers' online outage map useful, he said.
DTE also welcomed the probe into what spokeswoman Erica Donerson called "one of the largest ice storms in nearly a decade." She pledged that the utility will provide regulators with whatever information they need.
In the wake of criticism of the Lansing utility's response to the storm, a local state senator has called for it to be placed under the PSC's oversight.
Quackenbush declined to take a position on the expected legislation, saying the commission is neutral.
"We very much follow the lead of the Legislature on things like that," he said, later saying that he is unaware of a city utility ever being subject to state oversight before.
The Lansing utility, which is governed by a board appointed by the mayor, held a special meeting Tuesday. The utility is conducting an internal review, and on Wednesday Mayor Virg Bernero named a retired Michigan National Guard brigadier general to lead a separate review of the Board of Water & Light's ice-storm response.
He also asked state regulators to conduct an independent review of the final reports from the local investigations.