The Coast Guard said Friday experts are trying to figure out the best plan to recover unexploded ammunition found last weekend in the waters underneath New York City's Verrazano-Narrows Bridge.
The material has been there for some time, based on the corrosion, spokesman Charles Rowe said, anywhere from "a few years to a few decades."
Rowe declined to pinpoint the location, but said it's not in a shipping channel or common fishing area. He said the agencies involved - which also include the police, Navy and Army Corps of Engineers - are assessing what needs to be done to retrieve the material and how best to go about it.
It wasn't clear what the source of the ammunition was. The commercial diver who discovered the cache last weekend believes it comes from a 1954 barge accident, but Rowe couldn't confirm that.
The bridge, which connects Brooklyn to Staten Island, opened in 1964.
After seeing the munitions under water, diver Gene Ritter got in touch with Ken Hayes, president of Aqua Survey. The Flemington, N.J., company conducted a sonar survey of the area on Sunday.
Hayes said a sonar survey of the area was a safer way to go than diving near the ammunition, which mostly likely would not go off but was still dangerous.
"You've got to be real careful," he said.
The scan found the big debris pile that Ritter saw, Hayes said, along with three smaller debris piles. He sent the information from the scan to the Army Corps of Engineers.