Lauwersoog dyke passage opened: new tidal area in De Marnewaard

Initiators on the realisation of the tidal area 

Leo Wenneger, provincial executive of the Province of Groningen: “Thanks to the tidal culvert , 70 hectares of land inside the dykes in the Marnewaard are once again subject to the influence of the tides. This is unique in its design and scope, as it creates a richer habitat for countless plant and animal species from the Wadden Sea. It clearly demonstrates how we in Groningen are working to create a coastal zone that is in harmony with the dynamics of the Wadden Sea region. The ultimate goal is a broader coastal zone that is ready for the future (water safety) and offers space for unique nature, agriculture, recreation, and quality of life.”

Annette van Velde, board member of Noorderzijlvest Water Authority: “It’s wonderful that we can use the dyke reinforcement necessary for flood protection to also strengthen nature. Together with market players, we are building the most sustainable dyke in the Netherlands, with significantly lower emissions and the smart use and reuse of raw materials. It’s great that we can also incorporate ecological projects into this effort. A tidal culvert may sound like a hole in the dyke, but it is actually a well-thought-out and safe structure designed to allow water to pass through in a controlled manner—without compromising water safety.”

Mieke Langedijk, Director of Rijkswaterstaat Northern Netherlands: “At the boundary between the Wadden Sea and lake Lauwersmeer, we are combining protection against the water with space for nature development. Together with all stakeholders, we have invested in measures that help improve the ecological water quality of the Wadden Sea. The arrival of the tidal culvert is of great importance in this regard. As is the construction of artificial reefs and tidal pools at the foot of the dyke, and the salt marsh expansion near the Westpolder. With these measures, we are making the transition between the mudflats and dyke more natural. This is good for birds, fish, and underwater nature.”

Tidal area in the Marnewaard

The tidal culvert unlocks the new 70-hectare tidal area in De Marnewaard behind the Lauwersmeer dyke. With the opening of the culvert and the subsequent influx of seawater, a tidal area will be created. This will increase biodiversity and improve water quality. New habitats are expected to emerge for species such as samphire, sticklebacks, smelt, avocets, and spoonbills.

The culvert in the sea dyke of approximately 80 metres long and 2 metres wide, allows seawater to flow in and out of the tidal area in a controlled manner and within water level regulation limits.  For water safety, the tidal culvert has two sluice gates that can close the passage. This allows us to determine the water level in the tidal area. The location of the new tidal area is the old salt marsh area of the Marnewaard military training ground. This part of the site is not used for military activities.

Cooperation and financing 

The nature projects are an initiative of the Groningen provincial executive, Noorderzijlvest Water Authority, Rijkswaterstaat, together with the Groninger Landschap Foundation (acting on behalf of the nature organisations Natuurmonumenten (Dutch Society for Nature Conservation), Staatsbosbeheer (Dutch Forestry Commission), and the Groningen Nature and Environment Federation). The total cost of the projects amounts to 32 million euros. This amount is funded by the Programmatic Approach to Large Water Bodies (PAGW) of the Ministries of Infrastructure and Water Management (I&W) and Agriculture, Nature and Food Quality (LVVN), the Wadden Fund, the Province of Groningen, and funds from the NextGenerationEU programme.