By ROBERT JABLON
The Associated Press
LOS ANGELES (AP) — Underwater dump sites off the Los Angeles coast contain thousands of barrels of World War II-era munitions including anti-submarine weapons and smoke devices, marine researchers announced Friday.
A vast survey of known offshore sites in April identified the munitions. The survey was a high-tech follow up in a region known to have been the dumping ground for industrial and chemical waste from the 1930s through the 1970s.
Two underwater vehicles, one autonomous and the other remotely controlled, used sonar and high definition video to scan 135 square miles (350 square kilometers) of the sea floor, where mysterious boxes and barrels were strung out between the mainland and Santa Catalina Island, researchers said.
A 2021 survey had uncovered more than 25,000 “barrel-like objects” on the sea floor that possibly contained DDT and other toxic chemicals. High levels of the toxic chemical were previously found in sediments and marine mammals in the region, and DDT has been linked to cancer in sea lions.
However, later research, including from the U.S. Environmental Protection Agency, suggested that much of the contamination may have come from acid waste containing DDT that was stored in above-ground tanks and then dumped into the sea in bulk from barges rather than in barrels.
The April survey concluded that most of the objects lying thousands of feet below the surface were “multiple types of discarded military munitions and pyrotechnics,” according to a statement from the Scripps Institution of Oceanography at the University of California, San Diego. Scripps researchers led the effort.
They included anti-submarine depth charges and smoke floats used to lay down cover for warships.
The US. Navy said the munitions were probably dumped into the sea during the World War II era as ships returned to port, which at that time was considered a safe and government-approved disposal method.
In a statement, the Navy said it is reviewing the findings to determine “the best path forward to ensure that the risk to human health and the environment is managed appropriately.”