What began with the spotting of a then-unidentified mine has ended with the U.S. Navy pledging to maintain oversight of the ordnance used in its training exercises.

Sheila Murray, deputy public affairs for Navy Region Northwest, reported Aug. 30 the mine, which was discovered and deliberately detonated in the Puget Sound on the evening of Aug. 28, was determined to be from an exercise conducted by Naval Undersea Warfare Command, Keyport in 2005.

“This exercise was an opportunity for academia to demonstrate various unmanned underwater vehicles, and their capability to detect underwater objects and avoid submerged obstacles,” Murray said.

During this exercise, Murray elaborated, inert training mines were placed between Brownsville, Keyport and Bainbridge Island, but only a small number of the training mines were “positively buoyant.”

“Not all the training mines were recovered,” Murray said. “It has been confirmed the device destroyed (Aug. 28) was a positively buoyant, inert training mine used during the 2005 exercise.”

In order to avoid similar incidents in the future, Murray promised the Navy will survey its exercise areas to recover any remaining positively buoyant mines.

‘SAFEST PUBLIC MEASURE’

The initially unidentified mine was first discovered by the Washington State Department of Natural Resources Aug. 28, in the waters near Brownsville Marina.

U.S. Navy Explosive Ordnance Disposal — which Murray noted is responsible for military ordnance — responded jointly with the U.S. Coast Guard and local law enforcement, at the location of the mine, to assess the situation.

Following an initial inspection, Murray reported the moored mine showed signs of “decades of marine growth,” even though it would later be determined to be only 13 years old.

In the interests of public safety, the Navy and Coast Guard then established a safety stand-off distance of 1,500 yards from the center of the Kitsap County waterway, between Keyport, Bainbridge and Brownsville.

According to Murray, the responding Navy Explosive Ordnance personnel determined, “through an abundance of caution,” that the “safest public measure” would be to detonate the mine.

Murray explained that it was unknown at the time if the mine was inert, so it could not safely be towed to shore for further assessment, although she added the mine was towed to a location “determined to be safest to the immediate population” for this operation.

Even as Murray warned the public that evening of “an audible explosion before sunset today,” but predicted no danger to the public, she asked the public to stay away from shorelines in the immediate affected area.

The mine was detonated at 8:04 p.m. Aug. 28, but its detonation did not create a secondary explosion, which indicated to Murray that it was inert.

Murray offered the Navy’s thanks to its partner agencies for their support in the response, including the U.S. Coast Guard, the Suquamish Tribe, the state of Washington, Kitsap County, and the National Oceanographic and Atmospheric Administration.