Here's a list of canal aqueducts in the UK: https://en.wikipedia.org/wiki/List_of_canal_aqueducts_in_the...
The newest aqueduct I saw listed at https://en.wikipedia.org/wiki/Aqueduct_(bridge) is https://en.wikipedia.org/wiki/Mathur_Aqueduct , which was built in 1966. It's meant for irrigation water .