The accident occurred about five miles south of Yellow Bay around 8:30 a.m. The truck blocked one lane. The painstaking work of clearing the accident scene blocked traffic nearly all day on the roadway that hugs Flathead Lake.

As workers moved boxes out of the overturned trailer, they eventually moved one that was covering a spill valve on an acid container. The valve released, which started a leak.

The truck was not carrying hydrochloric acid, as previously reported. Phosphoric acid is commonly used in soda pop but can still be corrosive to skin. Kalispell's hazardous-materials team was called in to neutralize and contain the spill, which was confined to the area where the semi-truck had tipped over.

Montana Highway Patrol Trooper Terrance Rosenbaum said the truck driver was “sightseeing” when the truck veered. He was pulling a regular trailer and a pup trailer.

“The next thing he knew, the vehicle went to the right, toward the hillside and ended up flipping a tractor and the first trailer,” Rosenbaum said.

The highway was completely blocked off around 1 p.m. so tow crews could right the truck. One lane reopened nearly two hours later.

A semi-trailer truck carrying phosphoric acid flipped on its side on Highway 35 along the east shore of Flathead Lake on April 23. About 125 gallons of the acid spilled in the incident.

The accident occurred about five miles south of Yellow Bay around 8:30 a.m. The truck blocked one lane. The painstaking work of clearing the accident scene blocked traffic nearly all day on the roadway that hugs Flathead Lake.

As workers moved boxes out of the overturned trailer, they eventually moved one that was covering a spill valve on an acid container. The valve released, which started a leak.

The truck was not carrying hydrochloric acid, as previously reported. Phosphoric acid is commonly used in soda pop but can still be corrosive to skin. Kalispell's hazardous-materials team was called in to neutralize and contain the spill, which was confined to the area where the semi-truck had tipped over.

Montana Highway Patrol Trooper Terrance Rosenbaum said the truck driver was “sightseeing” when the truck veered. He was pulling a regular trailer and a pup trailer.

“The next thing he knew, the vehicle went to the right, toward the hillside and ended up flipping a tractor and the first trailer,” Rosenbaum said.

The highway was completely blocked off around 1 p.m. so tow crews could right the truck. One lane reopened nearly two hours later.