We measure chloride in lake Lauwersmeer
21 November 2025
This week, we measured how freshwater and saltwater move around the Clevering locks. This knowledge helps us to set up a smart monitoring network. The aim is to connect the freshwater in lake Lauwersmeer with the saltwater from the Wadden Sea. Together, we work to create a future-proof and natural lake Lauwersmeer.
Last week, we took measurements by boat at the Clevering locks. We studied the chloride content of the water at various locations and at various depths. We also looked at the flow velocities and flow direction. This gives us a better understanding of how freshwater and saltwater move in lake Lauwersmeer. Based on our findings, we also determine where measuring buoys can provide the best insights.
The measurements were carried out by Rijkswaterstaat Central Information Services, in close collaboration with the operational water managers of the Noorderzijlvest and Wetterskip Fryslân Water Authorities.
Why does it matter?
- More insight
We are studying how the water flows and how a limited amount of saltwater flows into the lake. This is necessary for research into the possibilities for a better transition between freshwater and saltwater. The knowledge we gain from these sailing measurements will help us develop options for a robust freshwater-saltwater connection. The research (the exploration)will continue until 2028.
How do we take the measurements?
- Safe and responsible
We only take measurements when there is enough freshwater to flush away the saltwater. After the measurements were taken, the chloride content was comparable to the initial situation. The locks are only opened when there is a small difference in water level between the Wadden Sea and lake Lauwersmeer and when the tide is going out. This ensures safety for the lock complex and water quality. - All measurements could be monitored by the administrators, allowing us to intervene if necessary.
What are the benefits?
- The measurements already give us data that provide us with a better understanding of how the freshwater-saltwater dynamics between the Wadden Sea and lake Lauwersmeer can work at the Clevering locks.
- We will also use the insights gained from this initial measurement campaign to determine where to place the measuring buoys in lake Lauwersmeer. These will be installed in early 2026.
