Central Maine Power, which had a record 470,000 customers lose power throughout the October windstorm, says its restoration costs will top $15 million, according to an initial cost estimate it filed Tuesday with state regulators.

The company still is invoicing for restoration costs, and said it would provide detailed cost information in a report to be submitted by Jan. 18.

“CMP’s service territory was hit with a devastating wind and rain storm event resulting in the greatest number of customer outages in CMP’s history, impacting nearly two-thirds of CMP’s customers,” Eric Stinneford, CMP’s vice president, treasurer, controller and clerk wrote in a notice to Harry Lanphear, administrative director for the Maine Public Utilities Commission.

Lanphear was not immediately available for comment.

CMP spokeswoman Gail Rice would not comment on how much of the costs ratepayers might see in their electric bills.

CMP has a $10 million reserve fund established in 2014, with $6 million set aside to cover costs resulting from larger storms and $4 million for smaller storms, the PUC’s Lanphear said last November.

That money was raised by increasing customer electric rates. CMP holds the reserve fund, but it carries some stipulations.

Lanphear in November gave an example of how the money would be used for a major storm like the October one. If the cost exceeds $12 million, CMP would pay $2 million from the reserve fund, its cap for any single storm. The remainder of the cost would be paid through a customer rate hike that the PUC would automatically approve if it found CMP’s storm outage repair costs legitimate, he said.

“The impact per every $5 million of storm costs would be about 35 cents per month for a typical bill,” he said at the time. That’s assuming CMP could recover the costs over a one-year period.

Emera Maine, which had 87,000 customers without power over the course of the storm, plans to inform the PUC of its outage costs by the middle of January, according to spokesperson Judy Long.

Both companies also must respond to a separate PUC investigation order issued in mid-December to file a report on how they handled the outage and restoration. That is due in mid-January.

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Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...