A manmade biotope
Tne priority of the ecological measures of the Master Plan Ems 2050 is recreating lost habitats along the river. These biotopes are special because they are influenced by the ebb and flow, meaning they are dry at times and submerged at others. Ideally, shallow water zones, brackish and freshwater reeds, sand and silt flats, and tidal riparian forest would form.
One of the attempts at creating such a biotope should be realised in the municipality of Westoverledingen, close to the former bend in the Ems near Coldemüntje. The area located behind the Ems dyke consists of the remains of a former Ems loop that was cut off in the first half of the 20th century. The Grotegaste oxbow that formed here was filled with dredged materials from maintenance of the fairway and was later completely separated from the Ems by the construction of the new main dyke line. A silted lake and few biodiverse biotopes are now located here.
Tidal inlet structures will be created in the tidal polder during construction, and a freshwater pond will be formed at the higher altitude of the planned area. Because it is expected that no water will be able to flow out of the Ems for a number of days during the summer because of greater sediment loads, additional irrigation via the Coldemüntje sluice will be considered. Along with the tidal polder that is expected to form tidal inlets, a freshwater pond is also expected to be created at the higher altitude of the planned area. A structure installed in the dyke to allow the influx of water should ensure that the uppermost layers of the water column around the flood waters can flow into the polder from the body of water. This will ensure that only the surface water of the Ems that it less heavily contaminated with sediment will enter the polder. The dyke line remains untouched. Furthermore, a settling basin should prevent excessively rapid silt buildup. The structures will be designed in such a way that fish can also pass through them.
Based on the NLWKN feasibility study submitted late last year, the Steering Committee for the Master Plan Ems 2050 decided in January to commence permit proceedings in the Leer district to realise the Coldemüntje tidal polder. Around 340,000 cubic metres of dredged materials must be removed to construct the polder. Plans are currently being discussed to determine how to disturb the residents as little as possible – including by leaving more material in the planned area. The municipality of Westoverledingen will constantly be kept up to date. The state will bear the expenses of around seven million euros.
Under the current circumstances, it is assumed that the measure is feasible and can be realised according to schedule (2020).