Plans to sink the retired aircraft carrier USS "Oriskany" off Florida as an artificial reef have been delayed for one month.
A Navy spokeswoman said the project could be scrapped if an environmental permit is denied.
The 888-foot ship is scheduled to be towed to Pensacola in early September from Corpus Christi, Texas.
Fuel, oil, asbestos and other contaminants are being removed during processing in Texas.
The Oriskany had been expected to arrive in Pensacola by Aug. 10.
The Environmental Protection Agency has been asked for a risk-based disposal permit.
The permit would let the Navy sink the ship about 25 miles southeast of Pensacola Pass -- without removing all materials containing solid polychlorinated biphenyls.
PCB's have been linked to cancer.
The EPA is reviewing a draft human risk assessment.