Photo: Repair Work At Lock 4

A Corps of Engineers contractor began prepping for winter maintenance on a foggy river morning at Lock and Dam 4, in Alma, Wis., in mid-December. 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. Similar repairs are being made at Locks and Dams 5 and 5A to ensure that critical infrastructure remains serviceable, with work scheduled to end in the spring before the navigation season starts back up. (Corps of Engineers photo by Patrick Loch)