The lake Filsø

Filsø was once one of the largest lakes in Denmark, covering an area of around 3,000ha, but over the centuries man has left his mark on the lake. The first water mill on the stream Henne Mølleå was constructed during the Middle Ages, as early as around 1140. The watermill was then a new way of harnessing the forces of nature, and with the construction of the weir it became possible to regulate the size of the lake.

From the end of the 1700’s the possibility of partially draining the lake to reclaim farmland began to be discussed, then in 1852 the weir controlling the water level of the lake was removed by the new owners of the Henne Mølle watermill. This caused the area covered by the lake to shrink from around 2,100 to 750 ha.. The land reclamation work at Filsø had begun. Nearly one hundred years later work on the drainage of the area began again, and in the years following World War II the drainage of Mellemsø and Søndersø was begun. By 1951 a further 750ha. of the lake had been turned into farmland. By this time only a fraction on the original lake remained , namely Fidde Sø which was the north east corner of the original lake.

In 2010 the Aage V. jensen Fund for Nature purchased Filsø. On the total of 2,300 ha of land bought by the fund, a new lake of 915 ha has been restored. Together with Fidde Sø and Sovigsund the total area of new lake is 1,030ha. . Thus today the remains of the original Filsø lake consists of three separate lakes: Mellesø, Søndersø and Fidde Sø.