TRENTON - The electricity company Exelon said Wednesday that it would close the Oyster Creek Nuclear Generating Station in 2019 - 10 years earlier than planned - but would not have to build costly cooling towers for it.

The Chicago-based company said changing markets and upkeep costs for the aging plant in the Forked River section of Lacey Township, Ocean County, had caused its value to decline.

The plant, 60 miles east of Philadelphia, "faces a unique set of economic conditions and changing environmental regulations that make ending operations in 2019 the best option for the company, employees and shareholders," Exelon Corp. president Chris Crane said.

He said low market prices and demand and the plant's need for continuing large capital expenditures had reduced its value.

"Also, potential additional environmental compliance costs based on evolving water cooling regulatory requirements - at both the federal and state government levels - created significant regulatory and economic uncertainty," Crane said.

Oyster Creek's boiling-water reactor is considered obsolete by today's standards. But the plant, which went online in December 1969, generates enough electricity to power 600,000 homes a year and provides 9 percent of New Jersey's electricity.

Because Exelon agreed to speed up the plant's shutdown, Crane said, New Jersey officials backed off their demand that it build one or more cooling towers to replace the current system of sucking water from Barnegat Bay into the plant and discharging it.

The state says that process kills billions of shrimp and tens of thousands of fish, crabs, and clams each year, and environmentalists have long wanted Oyster Creek to switch to cooling towers.

Exelon had balked at the state's insistence on cooling towers, saying it would shutter the plant rather than build them.

The company says the $800 million it would cost to build the towers is more than the plant is worth, and it asked the state to withdraw its demand last January.

Environmentalists say the job could be done for about $200 million.

The U.S. Nuclear Regulatory Commission granted the Oyster Creek station a new 20-year license in April 2009, rejecting concerns by opponents centered on corrosion to a metal enclosure that keeps superheated radioactive steam within a containment building.

Exelon had applied a strong coating material to the liner and removed a sand bed at the base of the reactor that was found to hold moisture that caused the corrosion.

Over the last year, the plant has been cleaning up the remnants of a leak of radioactive tritium from underground pipes that has since made its way to a major underground water source, although no wells or drinking-water supplies have been tainted.

Tritium occurs naturally in the environment at very low levels and may be released as steam from nuclear reactors.

The leaks have prompted the NRC to order its staff to look for better ways to detect and prevent leaks in buried pipes at all U.S. nuclear power plants.

Lacey Township Committeeman Brian Reid, an opponent of the cooling-towers proposal, said it was "a shame" that the plant would be shutting early.

"They would have had to spend a lot of money on those towers, and business is business," Reid said.

On Thursday, the administration of Gov. Christie was to reveal plans to protect the health of Barnegat Bay.

Sierra Club chapter director Jeff Tittel scoffed at the Oyster Creek deal, saying Exelon "gets to operate the plant for 10 years, then walk away with a pile of cash at the expense of the bay."