MANTOLOKING, N.J. — A century after World War I ended, discarded munitions from that and other wars continue to make their way onto beaches around the country.
Items ranging from tiny fuses to full-scale mines are displaced by beach replenishment projects, sucked from the ocean floor and pumped ashore, or by strong storms that uncover them.
The most recent discovery came earlier this month when seven WWI rifle grenades were found on the beach in Mantoloking, New Jersey, which is undergoing a beach replenishment project to undo damage from Superstorm Sandy more than five years ago.
Many of the items were simply dumped overboard at the end of World Wars I and II; others remain from military drills or target practice. They’ve been discovered in at least 16 states from New Jersey to Hawaii.
“Surprisingly or not, this stuff continues to turn up,” said Niall Slowey, an oceanography professor at Texas A&M University, who has studied the phenomenon extensively. “They disposed of millions of tons of this stuff.”
No one knows how many pieces of munitions remain offshore, partly because the military’s own records as to how much was disposed of aren’t great. A Defense Department report to Congress in 2009 said more than half of sea disposals of munitions was done in the Atlantic Ocean; the Pacific got another 35 percent, and lesser amounts were dumped off Hawaii, Alaska, the Gulf of Mexico and the Caribbean. The material was dumped as near as 5 miles from shore, in water as shallow as 50 feet.
Slowey and a colleague released a 2012 study estimating there are millions of pounds of undersea bombs in the Gulf of Mexico alone.
Disposal of unneeded munitions at sea was commonly accepted practice until 1970.
“They thought it was beyond harm’s reach,” Slowey said. “People could not envision that there would be any interaction with material that deep on the ocean floor. But there is a lot more on the sea floor than anyone could have envisioned.”