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Two explosive devices found submerged under Nampa-area bridge


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Divers inspecting one of the two explosive devices. | Courtesy Idaho Department of Transportation

BOISE — Crews performing maintenance on the Idaho Highway 45 bridge over the Snake River recently found two military explosive devices.

Divers inspecting the base of a bridge pier underwater discovered the first device Oct. 31. The contractor notified the Canyon County Sheriff’s Office, which helped contact and dispatch a bomb squad from the Nampa Police Department. Nampa police contained the explosive ordnance. The Mountain Home Air Force Base received the device and safely detonated it off-site, according to a news release from ITD.

In a video posted by ITD to their YouTube channel, divers inspecting one of the devices can be heard describing it as an artillery shell.

“We have found an artillery shell — we don’t know if it’s live or not,” a diver can be heard saying. “It looks like it’s about 28 inches long.”

The following day, a second device was discovered in the same area, roughly 20 feet underwater, ITD said. The contractor immediately halted construction. The base sent an explosive ordnance unit to assess the situation, where the device was determined to be secure where it was and posed no immediate risk to people using the bridge or boaters on the water.

“This is a very, very rare occurrence,” ITD spokesman Jake Melder told “We don’t have any documentation of anything like this happening before in Idaho.”

Melder said it is unknown how the devices ended up there, how long they had been there, or who put them there.

He said ITD will do a thorough search of the area before resuming repair work on the bridge.

Navy divers successfully removed the second unexploded ordnance and the Air Force disposed of it off-site. A sweep of the immediate area did not find additional devices.

“Thank you to the Owyhee and Canyon County Sheriff’s Offices, the Nampa Police Department, the Office of Emergency Management, Mountain Home Air Force Base and the Navy for their partnership in securing the (unexploded ordnance) and ensuring the construction zone is safe to resume operations,” Amy Revis, ITD District 3 Engineer, said in the news release. “Safety is a top priority for ITD, and proper protocol was followed in this rare circumstance to protect our employees, contractors, and the traveling public.”