The chief operating officer of a utility company heavily criticized for its response to Superstorm Sandy is stepping down.

The Long Island Power Authority announced Tuesday that Michael Hervey had tendered his resignation, effective at the end of the year. Hervey has been with LIPA for 12 years.

LIPA has come under withering criticism since Sandy knocked out power to more than a million of its customers on Oct. 29, both for how long it was taking to get power restored and for poor communication with customers.

There are about 10,000 outages in Nassau and Suffolk counties, just east of New York City, and LIPA officials have said they hope to have most of them resolved by Wednesday.

The company said Tuesday that 99 percent of those customers that can safely get power have it restored. But 35,000 customers that suffered significant flood damage need repairs on their properties before power can come back.

The majority of those customers are in the hard-hit Rockaways section of Queens, served by LIPA. The Consolidated Edison utility also had about 4,000 customers in that position, in Brooklyn and Staten Island.

A state report criticized LIPA in June for poor customer communications after last year's Hurricane Irene. The Department of Public Service noted LIPA's major problems in telling customers estimated power restoration times, faulting its computer system, which a consultant had found deficient in 2006.

LIPA acknowledged that customers weren't getting the information they needed, partly because of the system, which it is updating. Hervey said Monday that LIPA "accelerated that process" after Irene but it's still an 18-month to two-year procedure.

"We would have liked to have had it up and running for now," he said, "but it's just such a large magnitude computer system that it takes that long."

Hervey said the company would work with customers over the next several weeks as they get their homes repaired.

Gov. Andrew Cuomo on Tuesday announced an investigation into how utility companies prepared for Sandy, which killed more than 100 people in 10 states but hit New York and New Jersey the hardest, and how they handled the aftermath.

"From Hurricane Irene, Tropical Storm Lee, to Hurricane Sandy, over the past two years New York has experienced some of the worst natural disasters in our state's history," Cuomo said. "As we adjust to the reality of more frequent major weather incidents, we must study and learn from these past experiences to prepare for the future."