NEW YORK (Reuters) - As U.S. Northeast power outages in the wake of Hurricane Sandy and the recent Nor'easter storm dwindled to fewer than 167,000 customers in three states on Sunday, New York City's power company, Consolidated Edison Inc, said its costs alone could reach $450 million.

The U.S. Department of Energy said there were 166,499 customers without power in New York, New Jersey and West Virginia on Sunday following both storms.

The number was down from Saturday's tally of 289,239 in the three states and more than 8.5 million in 21 states along the East Coast after the hurricane came ashore on the New Jersey coast on October 29.

As the number of outages dwindled, the first utility cost estimates from the storms showed New York's Con Edison placing response and restoration costs at an estimated $350 million to $450 million, the company said in a statement.

Con Edison said it used its experience with Hurricane Irene in August 2011 - previously the largest storm in the company's history - as a basis for the estimates, but said Sandy caused five times as many outages as Irene.

A record storm surge across the Northeast, including in New York City, caused flooding and widespread damage to much of Con Edison's underground electrical equipment. In areas with overhead power lines, workers had to contend with more than 100,000 downed wires, blocked roads and flooding.

WHERE THE OUTAGES REMAIN

The majority of the remaining power outages were in New York, with more than 132,000 customers without, most of those served by the state's Long Island Power Authority (LIPA), the DOE report said.

LIPA has come under growing criticism from residents and New York Governor Andrew Cuomo as outages stretched into a third week.

LIPA on Saturday said 55,000 customers on Long Island and in the Rockaways, in the New York City borough of Queens, could be powered, but damage to homes was too severe and repairs or an inspection needed to be completed before the houses could reconnect to the grid.

The bulk of outages on Long Island remained in Island Park, Oceanside and the East Rockaway area, with smaller pockets in other south shore communities.

In New York City, Con Edison said it was on track to restore power by the end of the weekend to virtually all customers who can accept service.

The company's crews and thousands of utility workers from around the country were working to restore power to its more than 1 million customers affected by the storms.

In shoreline communities in Brooklyn, Queens and Staten Island, the company had identified about 30,000 customers who needed electrical equipment repaired and certified as safe before service could be restored.

Approximately 8,000 of those customers now had service, but others would not able to get service until their own internal equipment was repaired, tested and certified by an electrician as ready.

About 28,000 customers in New Jersey and about 5,700 in West Virginia were still without power on Sunday, the DOE report said.

FirstEnergy's Jersey Central Power & Light on Sunday said it restored service to 99 percent of its customers affected by the storms, with the remaining 19,000 customers that can receive service expected to have it by Sunday evening.

About 30,000 customers on the barrier islands and in shoreline communities in New Jersey - some of the most devastated after Sandy came ashore near Atlantic City - cannot be restored to service at this time due to massive infrastructure damage in that area, the company said.

(Reporting by Eileen Houlihan; Editing by Leslie Adler and Maureen Bavdek)