The city of Edam Netherlands was founded around a dam crossing the river E or IJe close by the Zuiderzee now known as the IJsselmeer. Around 1230 the channel was dammed. At the dam goods had to be loaded onto other vessels and the inhabitants of Edam could levy a toll. This enabled Edam to grow as a trade town. Shipbuilding and fishing brought Edam more wealth.

I spent time In The Netherlands back in the late 50's when the body of water was called Zuiderzee or South Sea. It was at that time a salt water sea. When I lived there in the early 90's it was now called the Ijsselmeer. The word meer is lake, now fresh water. This was an accomplishment turning part of the Sea into a fresh water lake.