The Federal Energy Regulatory Commission on Wednesday approved the construction of a natural gas pipeline underneath Long Island Sound.

State officials and environmental groups oppose the construction of a 22.6 mile Islander East pipeline, citing concerns that it could damage the sound’s ecosystem.

The project still needs approval from the federal Environmental Protection Agency and the Army Corps of Engineers.

The $182 million pipeline should be in full operation by winter 2004, but there isn’t a specific timeline set for construction, said John Sheridan, spokesman for Duke Energy, which co-owns the Islander East line with KeySpan Corp.

The pipeline proposal was approved despite a state moratorium on utility projects in the sound. Lawmakers who passed the moratorium this year want to study how best to handle numerous requests to place pipelines and power cables under the sound.

While the state has the authority to site power lines, FERC approves gas lines. As part of its moratorium, the state asked FERC to not approve any gas lines for one year. FERC Chairman Pat Wood III turned down that request in July.

“We find our approval of this proposal will benefit the public interest because it will increase the flexibility and the reliability of the interstate pipeline grid by offering greater access to gas supply sources,” FERC said in its decision.

FERC also is reviewing plans from Iroquois Gas Transmission System to build a gas pipeline across the sound. In August, the agency said the Iroquois plan “is environmentally preferable,” because it would cut the Sound crossing by 5 1/2 miles and affect fewer shellfish leases than the Islander East plan.

The Islander East pipeline would run through parts of North Haven, North Branford, East Haven and Branford to Brookhaven, N.Y.

The pipeline would supply local distribution companies and power plants in Connecticut and Long Island, as well as proposed electric plants with enough gas to heat as many as 600,000 homes, its owners said. Critics argue it would benefit only Long Island.

–Associated Press