ALBANY — New York conservation officials plan to list Long Island’s Great South Bay among the state’s “impaired waters,” a move to reduce pollution following a second deadly brown tide in two years.

The 45-mile natural harbor, which lies between Long Island and Fire Island and is an arm of the Atlantic Ocean, was once the source of nearly half the clams eaten in the United States.

Separately, Gov. Paterson and Sen. Charles Schumer have asked the Commerce Department to designate Great South Bay a commercial-fisheries disaster, making it eligible for federal aid.