Our contractor-partners begin prepping for winter maintenance on a foggy river morning at Lock and Dam 4, in Alma, Wisconsin, Dec. 14. On this morning the crew was in the initial stages of conducting guidewall repairs. Eventually crews will pump concrete into voids within the guidewall structures, which serve as extensions of lock walls to guide vessels into the lock chamber and provide mooring for long tows. The repairs are also being done at Locks and Dams 5 and 5A to ensure our critical infrastructure remains serviceable, with work scheduled to end spring 2019 before the navigation season starts back up.