The road over Sylvan Pass on the east side of Yellowstone National Park was temporarily closed Friday afternoon as crews worked to remove unexploded ordinance left behind as a result of avalanche mitigation work done, presumably during the previous winter.
According to a statement from the park’s public affairs office, the ordinance was found Friday afternoon near the roadway over Sylvan Pass, and the closure was expected to last a few hours while a team from Malmstrom Air Force Base near Great Falls, Mont. responds and destroys the shell.
During the winter, Yellowstone workers use a Howitzer cannon to launch shells into deep snow on the hillside over Sylvan Pass as a method of reducing the risk of avalanches. Not every shell explodes on impact, and one is occasionally found between the road and the base of the hills along the pass.
Additional information was not immediately available.
“Our office does not expect to put out additional information on this closure unless conditions change dramatically,” said the statement from Yellowstone public affairs.