Goals
For the Noorderzijlvest Water Authority, clean and healthy water, safe living with water, and sufficient water in every season are the most important tasks in the Lauwersmeer area.
Clean and healthy water
Under the Water Framework Directive, our water board is responsible for ensuring clean and healthy water in Lauwersmeer. Under the national PAGW (Programmatic Approach to Large Water Bodies) program, the task is to improve the ecological water quality of the Wadden Sea. By improving the transition zone between the sea and the lake, we are contributing to better ecological water quality and a strong natural environment in both bodies of water.
Importance of fish migration
Until 1969, what is now Lauwersmeer was still the Lauwerszee. Then, for water safety reasons, it was closed off from the Wadden Sea with dikes and locks and became a freshwater lake. This had negative consequences for vegetation, fish, and birds. Fish, for example, need brackish water to be able to adapt to increasingly salty conditions. And vice versa, to get used to increasingly fresh water. Such a natural transition is therefore very important for fish migration (the movement of fish between the sea and fresh inland waters). A drastic separation of fresh and salt water is not necessary for water safety. It is technically possible to allow more salt water on the north side of Lauwersmeer for a better transition to the fresh water in the southern part of the lake.
Improving water quality
Together with other regional partners, we are exploring ways to improve water quality and gradually restore the original ecosystem.
Goals
- A transitional area between fresh and salt water in Lauwersmeer and the Wadden Sea provides more variety in environments (salt, brackish, and fresh). This increases the biodiversity of fish, underwater animals, birds, and plants.
- We want to create a connection between the Wadden Sea and Lauwersmeer lake to allow free fish migration. In the short term, this can be achieved by improving the fish passability of the R.J. Clevering locks with fish-friendly sluices. Healthy fish stocks help to improve water quality and vice versa.
- We want to combat pollution from pesticides and drug residues and control exotic species that threaten native species.
Living safely with water
The water boards are responsible for maintaining safe Wadden Sea dikes. Lauwersmeer also helps to keep the area safe and prevent flooding in the surrounding area. The Noorderzijlvest water authority manages the water in Lauwersmeer and part of the dikes surrounding it. Wetterskip Fryslân manages the other dikes. In the future, climate change will lead to increased precipitation. This means that more water from Groningen, Drenthe, and Friesland will need to be drained via Lauwersmeer.
Sea level rise
Currently, excess water flows into the Wadden Sea via free fall (water flows from higher to lower areas). The R.J. Cleveringsluizen locks play an important role in this process. These locks ensure that water from the Frisian and Groningen rivers is discharged into the sea. This discharge takes place during low tide, when the water level in the sea is lower than in the lake. The discharge window—the number of hours per day that discharge is possible—is becoming smaller as a result of higher sea levels, while more extreme precipitation means that large amounts of water must be discharged quickly and increasingly often. Free fall will no longer be sufficient in the long term.
Water safety is a prerequisite
We are therefore exploring not only how a freshwater-saltwater transition can lead to nature restoration, but also how we can combine this with a water management system that can adapt to sea level rise and climate change. Water safety is a prerequisite for the solution that we ultimately come up with together. The measurements carried out via the saltwater monitoring network in and around the lake also play a role in this. We want to be able to control the inflow or reduction of salt water as precisely as possible.
Sufficient water in every season
Fresh water flows naturally from Friesland, Drenthe, and Groningen to Lauwersmeer and then to the Wadden Sea. In spring and summer, especially during dry periods, additional fresh water comes from the IJsselmeer. This helps to maintain the water level and prevent salinization. Fresh water is important for the area. It supports agriculture in the coastal area and strengthens the transition from fresh to salt water between the Wadden Sea and Lauwersmeer.
South side of the lake remains fresh
Dozens of farmers grow seed potatoes around Lauwersmeer. The land is actually old seabed. The top layer of the fields contains fresh water. Underneath that is salt water. Because fresh water is lighter than salt water, the salt water moves downwards. Farmers are concerned that if Lauwersmeer becomes saltier, there is a risk of salinization. This would result in more salt in the agricultural soil, making it impossible to grow potatoes there. Research shows that limited inflow of salt water does not necessarily affect agricultural land. That is why the plan is to make only the northern part of Lauwersmeer brackish for nature restoration. The southern part—which is important for agriculture—will remain fresh, partly due to the water supply from the rivers. In this way, both interests, nature restoration and the future of agriculture, can coexist.
Future availability of fresh water
A sufficient supply of fresh water cannot always be guaranteed in the future. Fresh water flows from Friesland and Groningen to Lauwersmeer and the Wadden Sea. During dry periods, fresh water is supplied from the IJsselmeer to maintain the water level and prevent salinization.
The water board cannot guarantee that sufficient fresh water will always be available. Climate change is causing more frequent droughts, reducing the supply of fresh water and increasing demand for it. At present, there is still enough water coming from the IJsselmeer during dry periods. In the future, this will change and, if no measures are taken, we may face water shortages more often.