How the Grevelingen area was formed
Years ago, the Grevelingen and other inlets, such as Haringvliet and Oosterschelde, together formed the outlets of the Rhine, Meuse and Waal rivers into the North Sea. The difference between low and high tide was around 2.5 metres. On 1 February 1953, the dikes in the southwest of the Netherlands burst during a heavy storm. Large parts of the Schouwen-Duiveland and the Goeree-Overflakkee area were flooded.
The Delta Plan was developed to prevent a similar disaster from occurring in the future. This plan included building the Grevelingen Dam (completed in 1965) and the Brouwers Dam (in May 1971). The Brouwers Dam effectively closed off Lake Grevelingen from the North Sea.
Closing off Lake Grevelingen meant that there was no more tide. The present-day water level is fixed at 0.20 metres below Normal Amsterdam Water Level (NAP). The shallow areas, which were previously above water only during low tide, permanently became areas of dry land. In the period after 1971, money from the central government was used to develop the area into the beautiful nature reserve and recreation area that it is today. In 1978, Lake Grevelingen was again connected with the North Sea when a lock was built in the Brouwers Dam. This allows the water in the Grevelingen to be continually refreshed with salt water from the North Sea.
Lake Grevelingen was created when the area was closed off by the dam in 1971. The lake has a total surface area of 11,000 hectares of water, with around 4,000 hectares that are less than 1.50 metres deep. The elimination of the tide created an area of approximately 3,000 hectares which permanently became dry ground. Most of this land was turned into a nature reserve. Around 300 hectares of land, mostly along the two dams, was developed as a recreation area.