On 15th November, the day at which de Haringvliet sluices exist 47 years, minister Cora van Nieuwenhuizen (infrastructure and Water) put the ‘Kierbesluit’ into operation, together with her administrative partners of Water authority Hollandse Delta and Drinking water company Evides. This does not automatically mean that the sluices will be opened on that day. This only happens when the discharge of the river is high enough. This is prescribed in the ‘Kierbesluit’
The aim of the ‘Kierbesluit’ is to promote the international fish migration and to improve the biodiversity. By opening the door of the Haringvliet sluices regularly, migrating fish like salmon and seatrout can swim inside to spawn.
Another effect is that the western part of the Haringvliet becomes saltier. In the ‘Kierbesluit’ it has been guaranteed that the intake points east of the line Middelharnis-Spui can take water in. At low river discharges the sluices are closed. Rijkswaterstaat closely watches whether the salt intrusion does not exceed the agreed on boundary, with an extended research and monitoring programme. In addition, Water authority Hollandse Delta and drinking water company Evides monitor the intake points of fresh water.
On 15th November 1971 Queen Juliana opened the Haringvliet Sluices. This Delta work contributes largely to the safety concerning flooding and the availability of fresh water in the western part of the Netherlands. The ‘Kierbesluit’ adds a third function: a better passage way for internationally migrating fish. The fresh water supply and safety remain guaranteed.
More information (in Dutch): https://www.kierharingvliet.nl/nieuws/2018/10/15-november-treedt-kierbesluit-in-werking.html