Siltation in Lower Saxony’s inland lake system continues to progress. This is now confirmed by new measurements taken by the Association for the Preservation of Lake Steinhude (VESM): according to these, there are now between 15 and 16 million cubic metres of silt on the lake bed. In the last comparable measurement in 2019, the figure was 14.4 million cubic metres. This means that the volume of silt has increased by around one to 1.5 million cubic metres within seven years.
You can read more about the causes of silting and the association’s efforts here:
This is how the measurements were taken
The measurements were carried out from late March to early July 2026. According to the association, just under 1,000 kilometres of survey route were recorded using echo sounders and GPS, involving approximately 1,000 hours of voluntary work. More than 1,100 additional manual control soundings were carried out to verify the results. More than 90 per cent of the control measurements confirmed the echo sounder data. SPE Dredging Solution GmbH, which had already carried out the last survey in 2019, provided the measuring equipment (the same as on that occasion) and analysed the results in the same way as seven years ago to ensure direct comparability. According to VESM, the result is clear: “The dredging carried out in recent years was clearly insufficient. This has exacerbated the problems with the waterway’s usability.”
At the same time, the relevant authorities have, as part of of the new lake development plan A further depth survey was also carried out. They reached a similar overall conclusion: in large areas, the “thickness of the silt layer” had increased. At the same time, there were also areas where less sediment was found. The structure of the deeper channels, known as ‘deipen’, is said to have remained largely unchanged.
Every year, more sludge is added
The real problem, however, becomes clear when looking at the annual figures. According to the state authorities, an estimated 52,000 to 64,000 cubic metres of new sludge is currently being produced at Steinhuder Meer each year. Since 1980, however, an average of only around 30,000 to 40,000 cubic metres has been removed annually. The increase now observed is therefore not surprising. The new Lake Development Plan II therefore aims to take stronger countermeasures in future. In future, dredging is to be based on the actual rate of new sediment formation and carried out specifically where the sediments particularly impair the use and maintenance of the lake. For the time being, however, this simply means that the annual rate of new sediment formation is to be offset. The existing sludge mound, which amounts to up to 16 million cubic metres, would not be reduced as a result.
Fewer nutrients, less new sludge
However, the state is not relying solely on dredging. According to the calculations in the lake development plan, nutrient inputs are a major part of the problem. Around 2,000 kilograms of phosphorus currently enter the lake every year. The target is to reduce this to around 520 kilograms. To this end, various measures are planned along the tributaries. The reasoning behind this is that, in the long term, fewer nutrients should also slow down the formation of new sludge. The VESM believes this does not go far enough. In light of the new measurement figures, the association is calling for significantly more intensive dredging and additional options for storing the dredged material.
Where should the sludge go?
The dredged sludge must be transported to the sea’s catchment area so that it can be drained back into the sea. However, according to VESM, an extension of the Kolkdobben polder would not be sufficient. Last year, the association therefore proposed an area in the Toten Moor. A large part of the area has already been pre-drained and is currently undergoing peat extraction. According to the association, work could begin with a small area, which would be filled with sludge to a depth of around one metre. After a few years of vegetation growth, bog mosses could be established there. The association is certain that only through significantly greater annual dredging can the sea be saved for future generations.
What does this mean for water sports enthusiasts?
The Steinhuder Meer is unlikely to become unnavigable overnight. The authorities emphasise that the structure of the key dykes has largely been preserved. Nevertheless, this development remains relevant for water sports. The Steinhuder Meer is extremely shallow to begin with. Even relatively minor changes in water depth can therefore determine which areas are still safe for navigation and whether, for example, regattas are possible. Ernst Greten, chairman of the Association for the Preservation of the Steinhuder Meer (VESM): “If things carry on like this, we won’t be able to hold any fair regattas here any more. It’s a disaster for sailing in the region.”
The new lake development plan also explicitly takes water sports into account. The aim is to preserve the Steinhuder Meer both as a valuable natural area and as a usable body of water. It remains to be seen whether the planned combination of dredging and measures to tackle nutrient inputs will be sufficient to achieve this.
Jill Grigoleit
Editor Travel