On Thursday, September 25, 2025, the dike passage in the Lauwersmeerdijk was ceremonially opened, creating a new 70 ha tidal area in De Marnewaard. This enhances the living environment for plants and animals. Rijkswaterstaat collaborated with the Province of Groningen, Water Board Noorderzijlvest, the Wadden Fund, and various nature organizations.
Water Safety and Nature Development
The Lauwersmeerdijk will be reinforced until 2026 as part of the national High Water Protection Program (HWBP) . This will protect the dike for the next 50 years against rising sea levels and extreme weather. At the same time, we are making the transition from mudflat to dike more natural. We are doing this with three ecological projects. In addition to the tidal culvert and the tidal area Marnewaard, we are also working on:
- The construction of artificial reefs and tidal pools at the foot of the dike
- The natural salt marsh development at the Westpolder
These nature measures are part of the Rijksprogramma Programmatische Aanpak Grote Wateren (PAGW). By softening hard boundaries, a richer living environment is created. With the arrival of the tidal culvert, artificial reefs, tidal pools, and salt marsh expansion, we are making the transition between mudflat and dike more natural, says Mieke Langedijk, director Network Development Rijkswaterstaat North Netherlands. This is good for birds, fish, and underwater nature.
The Tidal Culvert in the Lauwersmeerdijk
The new tidal culvert connects the Wadden Sea with the inland area in De Marnewaard. Through the 80 m long structure, seawater flows in and out in a controlled manner, with a tidal difference of about 20 cm. This creates conditions in which species such as sea asparagus, sticklebacks, smelt, godwits, and spoonbills can thrive.
For water safety, the passage can be closed with sluices, allowing us to control the water level in the area. The new tidal area is located on part of the military training ground Marnewaard. Defense has made this area available; it is currently not used for military activities.
Collaboration in the Wadden Area
The nature projects around the Lauwersmeerdijk are a joint initiative of Rijkswaterstaat, the Province of Groningen, and Water Board Noorderzijlvest. The Groninger Landscape Foundation, Natuurmonumenten, Staatsbosbeheer, and the Nature and Environment Federation Groningen are also involved. The funding comes from the Ministry of Infrastructure and Water Management, the Ministry of Agriculture, Nature and Food Quality, the Wadden Fund, the province, and the European program NextGenerationEU.
