Dive Brief:

• The cause of a dip of more than 2 feet in the surface of Interstate 43 on the Leo Frigo Bridge in Green Bay, Wis., is a buckled bridge pier in the Fox River.
• Piling under Pier 22 of the bridge, which climbs to 120 feet over the river, sagged on Sept. 25 and again a bit more on Oct. 3.
• The state Department of Transportation, which is building supports to fix the sag, is still investigating, but says corrosion likely was caused by the composition of the soil and varying water tables beneath of the river bottom.

Dive Insight:

Only one pier let the road droop, but test pits have found lesser degrees of corrosion on adjacent piers. Meanwhile, though, the Federal Highway Administration told the state that it will pick up the tab for emergency repairs done within six months of the event because the state did nothing wrong.