A major power cable connecting Long Island to the mainland has failed and is leaking a "minimal amount" of nontoxic fluid into Long Island Sound, officials have confirmed.

The New York Power Authority, which owns the cable and leases it to LIPA, said in a statement to Newsday that it is overseeing repairs of the 345-kilovolt cable, which provides the Island with upward of 600 megawatts of electrical capacity. NYPA said temporary loss of the cable will not affect electric service on Long Island, which the agency said has "sufficient supplies of power from [other] on-island and off-island sources."

The 23-mile cable, installed in 1991, connects the Long Island grid at East Garden City to a Con Edison electric station in Sprain Brook, Westchester County. According to material on the Long Island Power Authority website, the underwater portion of the cable is built of "self-contained dielectric fluid-filled cables that operate under high pressure." The leak has been identified in a portion of the cable three miles from Long Island, according to NYPA.

NYPA said the cable failed on Monday.

The failure comes as Gov. Andrew M. Cuomo is calling for speeding up improvements to the state's bottlenecked electric transmission system.

"We still have a problem getting low-cost, clean, renewable power up from downstate to upstate, which is costing ratepayers $600 million a year," Cuomo said Wednesday in his State of the State address. "It can take up to two years, believe it or not, to get a new transmission project approved."

In its Wednesday night statement in response to Newsday questions, NYPA said it was overseeing the repairs to the underwater cable in coordination with PSEG Long Island, the new grid operator for LIPA, and Con Edison.

NYPA also was working with the state Department of Environmental Conservation because of the spill, as well as the U.S. Coast Guard.

PSEG Long Island spokesman Jeff Weir said the company didn't expect any impact on service as a result of the cable failure, but said it was too early to say whether there would be a financial impact.

NYPA said the leak of nontoxic insulator fluid was less than 5 gallons per hour, an amount it described as "minimal."

NYPA, a public power provider that operates generating plants throughout the state and thousands of miles of transmission lines and cables, said it plans to reroute energy service to Long Island through a second line.

"We plan to reconfigure the system to use a spare cable that is already installed under the Sound so that we can return the transmission line to full operation as early as possible," the agency said.

The problem isn't the first for energy lines onto Long Island. In March 2012, transformers connected to the 660-megawatt Neptune Cable under the Atlantic Ocean malfunctioned, sharply reducing the cable's capacity for more than a year. In 2009, one of three cables between Northport and Norwalk, Conn., also failed, requiring shutdown until 2011.

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