Getting in on winter maintenance - Lock and Dam 9 undergoes guidewall repairs during the non-navigation season. The site, near Eastman, Wisconsin, is one of several of the district's critical facilities receiving millions in repairs and upgrades to ensure their serving the nation for years to come.The work includes divers ensuring the forms are properly placed and secured before concrete is pumped 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.