A federal appeals court on Friday cleared the way for the creation of a new disposal site in eastern Long Island Sound for potentially hazardous materials dredged primarily from Connecticut harbors to maintain them for shipping and other maritime commerce.

The victory is another milestone in a decades-long disagreement between Connecticut and New York, principally over disposal of dredge spoils from New London Harbor and the Thames River, which require periodic channel clearing to accommodate the submarines berthed at the U.S. Naval Submarine Base in Groton.

Connecticut is also spending hundreds of millions of dollars to make New London Harbor the supply depot for an offshore wind energy industry. New Haven and Bridgeport also have harbors, prone to silting, with commercially valuable maritime industries.

New York, with maritime interests on Long Island that consist primarily of recreation and commercial fishing, has long contended that dredged spoils from New London, which the court said can now be disposed of offshore in the east end of the Sound, contain potentially toxic elements hazardous to marine life.

Connecticut and the U.S. Environmental Protection Agency, both on the winning side of the decision, contend that plans for the eastern disposal site meet environmental standards.

“This is a full and complete victory for Connecticut’s maritime economy,” state Attorney General William Tong said Friday.

“Thousands of jobs and billions of dollars in revenue depend on the ability to dredge and safely deposit materials,” he said. “The Eastern Long Island Sound site was selected after exhaustive review and public input, and any disposal of dredged materials will require full environmental review and compliance with Connecticut water quality standards. We hope that we can now bring this period of litigation to a close and finally begin this vital work.”

New York, after initial opposition, agreed previously on the establishment of dredge spoil disposal sites in the western and central Sound. There had been two eastern Sound disposal sites, one off New London and one near Cornfield Shoals, but they were intended to be temporary.

The federal appellate decision released Friday afternoon upholds the EPA’s approval of a new site that would comprise the western half of the existing New London site and two new adjacent areas to its west.

Tong called dredging in New London “crucial to Connecticut’s maritime economy.”

Supporting establishment of an eastern Sound site were the Electric Boat Division of General Dynamics, which builds submarines for the Navy in New London Harbor; the Connecticut Port Authority, the Connecticut Harbor Management Association and Cross Sound Ferry, which runs points to Orient Point on Long Island and to Block Island. The U.S. Army Corps of Engineers, which oversees dredging projects, has said that without dredging, the ability to launch and build submarines in Groton “would be eliminated.”

Tong said any disposal of dredged materials will require a full review of environmental impacts and must comply with Connecticut’s Water Quality Standards.