Goals
For the Noorderzijlvest Water Authority, clean and healthy water, waterproofing the future, and enough water in every season are the most important tasks in the lake Lauwersmeer area.
Clean and healthy water
Under the Water Framework Directive, our water authority has the task to ensure clean and healthy water in lake Lauwersmeer. Under the national PAGW (Programmatic Approach to Large Water Bodies) programme, 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 contribute to a better ecological water quality and a strong natural environment in both bodies of water.
Importance of fish migration
Until 1969, what is now lake Lauwersmeer was still the Lauwers sea. After that it was closed off from the Wadden Sea with dykes and locks and became a freshwater lake for water-safety reasons. 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 freshwater. Such a natural transition is extremely important to fish migration (the movement of fish between the sea and fresh inland waters). A drastic separation of freshwatr and saltwater is not necessary for water safety. It is technically possible to allow more saltwater on the north side of Lauwersmeer for a better transition to the freshwater 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 freshwater and saltwater in Lauwersmeer and the Wadden Sea provides more variety in environments (salt, brackish, and fresh). This increases the biodiversity of fish, aquatic animals, birds, and plants.
- We want to create a connection between the Wadden Sea and lake Lauwersmeer to allow free fish migration. In the short term, this can be achieved by improving the fish passage at the R.J. Clevering locks with fish-friendly discharge. Healthy fish stocks help improve water quality and vice versa.
- We want to combat pollution from pesticides and drug residues and control exotic species that threaten native species.
Waterproofing the future
The water authorities are responsible for ensuring the safety of the Wadden Sea dykes. Lake 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 dykes. Wetterskip Fryslân manages the other dykes. 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 lake 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. Clevering 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 suffice in the long run.
Water safety is a prerequisite
Therefore, we are exploring a freshwater-saltwater transition can lead to nature restoration, and 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 with the saltwater monitoring network in and around the lake also have a role to play. We want to be able to control the inflow or reduction of saltwater as precisely as possible.
Enough water in every season
Freshwater flows naturally from Friesland, Drenthe, and Groningen to lake Lauwersmeer and then to the Wadden Sea. In spring and summer, especially during dry periods, additional freshwater comes from lake IJsselmeer. This helps to maintain the water level and prevent salinisation. Freshwater is important to the area. It supports agriculture in the coastal area and strengthens the transition from freshwater to saltwater between the Wadden Sea and lake Lauwersmeer.
South side of the lake remains fresh
Dozens of farmers grow seed potatoes around lake Lauwersmeer. The land is actually old seabed. The top layer of the fields contains freshwater. Underneath that is saltwater. Because freshwater is lighter than saltwater, the saltwater moves down. Farmers are concerned that if Lauwersmeer becomes saltier, there will be a risk of salinisation. This would result in more salt in the agricultural soil, making it impossible to grow potatoes. Studies show that a limited inflow of saltwater does not necessarily affect agricultural land. So, the plan is to make the northern part of Lauwersmeer brackish for nature restoration, but not the southern part. The southern part—which is important for agriculture—will remain freshwater, 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 freshwater
A sufficient supply of freshwater cannot always be guaranteed in the future. Freshwater flows from Friesland and Groningen to lake Lauwersmeer and the Wadden Sea. During dry periods, freshwater is drawn from lake IJsselmeer to maintain the water level and prevent salinisation.
The water authority cann ot guarantee that sufficient freshwater will always be available. Climate change is causing more frequent droughts, reducing the supply of freshwater and increasing the demand for it. At present, there is still enough water coming from lake IJsselmeer during dry periods. In the future, this will change and, if no measures are taken, we may face water shortages more often.