Building on the steady growth of river navigation in the seventeenth century, ‘dead-water’ canals using pound locks were being built in Ireland in the 1730s.
Exeter had been linked to Topsham by a new cut in 1564-6, certainly the first recorded use of the pound lock, the critical technology for inland navigation.
Origin
Late 18th century: pound from pound3, in the sense 'body of still water, pond'.