The rehab work was necessary at the locks to extend their lifespan. Construction began on the youngest, Peoria, in 1936 and on the oldest, Marseilles, in 1920. 

https://www.waterwaysjournal.net/2020/10/30/illinois-waterway-locks-reopen-for-business/?fbclid=IwAR3LKKgckyoClJBrlqASRRQ1fkc-I8ZazZhxoNA-RHFk5QR0LULnItxBhDM