The spill occurred Friday at about 11:20 p.m. from the barge Boston No. 30.
The company Boston Marine Transport, Inc. reported the spill. Company crews are working to determine how much fuel was dumped into the water, and is working with an oil spill cleanup organization.
The Coast Guard says both the New York State Department of Environmental Conservation and the New Jersey Department of Environmental Protection are actively involved in the spill response.
The Coast Guard is urging mariners to use caution because of the pollution. All waterways remain open.
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