Plastic explosives from a mining operation in Canada have been showing up in Lake Roosevelt with some degree of regularity, the most recent near Crescent Bay.

A tube of the explosives, about a foot long and several inches wide, was detonated at Crescent Bay by the Spokane Bomb Squad on July 31. The Grand Coulee Volunteer Fire Department was on standby during the detonation.

One local resident, who saw the detonation, said it made a pretty big bang.

Lake Roosevelt National Recreation Area Chief Ranger Marty Huseman said that to her knowledge that was the first plastic explosive tube found this far down the Columbia River. She stated that 50 or more of the explosive devices have been found, and are somewhat inert because they have been in the water for some time.

The National Park Service first started seeing the plastic material labeled "Senatel Magnafrac" during the spring drawdown, April 22, near milepost 243 on Highway 395, north of Kettle Falls. A number of the explosive tubes have been found since, and the Spokane Bomb Squad has been called in to handle at least four of the detonations.

Ranger Huseman said a "British Columbia firm that had the explosive materials has a local vendor who has handled many of the devices."

The tube explosives are used by mining companies doing excavations.

Dan Foster, superintendent of the Lake Roosevelt National Recreation Area, said the plastic needs a detonator and charge to be active.

While the explosive tubes are no threat to the general public, anyone finding one should call 911. It is illegal to have the material without a permit or license, officials stated.

National Park Service rangers are working with the sheriffs offices in Stevens and Ferry counties on the explosive materials when they show up.

NPS officials stated that it is assumed that more of the materials will show up in Lake Roosevelt in the future.