The dam in this movie exists to this day. It is called the Afsluitdijk, a 32.5 kilometer long dam and causeway between the provinces of Noord-Holland and Friesland. Building started in 1927 and was finished by 1932.
The original plan was to drain the Zuiderzee and make a big "polder" despite fierce opposition of the fishing industry. After the floods of 1916 and the famine of 1918 most opposition ceased and Dutch parliament agreed with the plan which was never fully realized.. The resulting IJsselmeer (since 1932) is one of the biggest inland lakes of Europe.