Rhode Island's worst oil spill was the result of criminal negligence that left a barge and tug improperly equipped to navigate stormy winter waters, its owners said in agreeing to pay $7 million in fines.

The spill of 828,000 gallons of home heating oil in January 1996 happened after winter storm warnings were ignored, the companies and the tug captain also acknowledged, U.S. Attorney Sheldon Whitehouse said Thursday.The plea agreement with Eklof Marine Corp. of New York's Staten Island borough, its president and two affiliates must be reviewed by federal and state courts.

Whitehouse said the fines, if approved, would be the largest criminal fines paid in Rhode Island's history and the largest environmental fines ever paid in New England.