What European country would create a polder?

A polder is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The most notable example of polder construction is the system developed adjacent to the IJsselmeer (Zuiderzee) in the Netherlands. The Netherlands has a large area of polders: as much as 20% of the land area has at some point in the past been reclaimed from the sea, thus contributing to the development of the country. Therefore, the European country that would create a polder is most likely the Netherlands. However, other countries such as Belgium, Germany, and France also have some polders.