Council of State: Expansion of balancing lake Onlanden may proceed
On 2 April 2026, the Council of State issued a ruling in the interim relief proceedings regarding the project decision on the optimisation of balancing lake De Onlanden. During the proceedings, several residents expressed concerns about the potential impact of the balancing lake on their living environment. The Council of State ruled that work on optimising the balancing lake may continue. This expansion will enable the water authority to further strengthen water safety in the region. This aligns with the public interest in keeping the surrounding area flood-free.
Work on balancing lake may continue
The water authority is satisfied, from a hydraulic-engineering perspective, that the construction of the additional balancing lake may proceed. The expansion of balancing-lake capacity is necessary to protect the surrounding area from flooding. In extreme weather conditions, the balancing lake can be used to store up to 12.7 million cubic metres of water. This allows us to minimise flooding in the city of Groningen and surrounding villages as much as possible.
Continued: appeals and enforcement
Although the ruling on the project decision provides clarity regarding the project’s current progress, several appeals are still pending. These will be heard in the coming period. In the meantime, preparations and work on optimising the balancing lake will continue. The water authority will keep the local community informed of the progress and activities in the area.
We realise that this decision may be disappointing to residents in the area. We remain available to answer any questions and will be please to speak with residents whenever the need arises.