Between 1901 and 1975, the U.S. military used Culebra and adjacent islands and cays. Initially, it was used as a coaling station and a radio transmitter facility. Eventually the U.S. Navy established areas for naval gun firing and aerial bombing. The U.S. Marines held advanced base defense exercises on the island that included land maneuvers, artillery and small arms firing, and amphibious training. The military stopped firing on Culebra in 1975, but munitions are still on the island and in the water.
On behalf of the Department of Defense, the U.S. Army Corps of Engineers manages the Defense Environmental Restoration Program for Formerly Used Defense Sites (FUDS). All of the island of Culebra, Culebrita, Cayo Luis Peña, Cayo Norte, other nearby cays and surrounding water are within the Formerly Used Defense Site. The Corps divided the site into 14 project areas. One of those is an area where metallic debris may have been dumped. In the other 13 areas, known as Munitions Response Sites (MRS), the Corps is concerned that there may be military munitions present.
The entire Northwest Peninsula of Culebra was used for naval shore and aerial bombardment. The deed that transferred the land, including Flamenco Beach, to the Commonwealth of Puerto Rico makes the Commonwealth responsible for restoration, including removing munitions. That means, Congress has to tell the Corps to work in this area. In response to a congressional request, the Corps studied the part of the Northwest Peninsula the Commonwealth owns to determine the type and amount of munitions remaining. In 2014, under Section 317 of Public Law 113-291, the Corps received authorization from Congress to decontaminate certain public use areas within the Northwest Peninsula. These areas include portions of Carlos Rosario Beach, Flamenco Beach, Tamarindo Beach, the campground, and Carlos Rosario Trail. The remaining acreage not covered by these areas remains the responsibility of the Commonwealth of Puerto Rico to restrict access and/or provide remediation.