A federal official has identified the substance that spilled into Sandy Hook Bay yesterday as diesel fuel.
The fuel is likely to evaporate Friday, NOAA Emergency Response Coordinator Frank Csulak tells News 12 New Jersey.
A Coast Guard crew confirmed a 2-mile-long, 300-foot-wide light sheen on the water on Thursday afternoon.
A state Department of Environment Protection spokesman tells NJ.com that the Coast Guard crew smelled a slight odor of fuel near a Sandy Hook ferry dock.
A boom was deployed to shield Horse Shoe Cove, which was deemed the only sensitive area that the sheen could impact, according to the US Coast Guard.
State and federal responders were unable to relocate the sheen on Thursday evening.
Officials are concerned that the spill could impact wildlife that inhabit the bay, including seals that migrate to the area each winter.
The incident remains under investigation.
The Associated Press contributed to this report.