Clean water for the Groote Meer
At the heart of Grenspark Kalmthoutse heide is the Groote Meer, one of the Netherlands' largest fens. Due to water inflow from agriculture, the water quality is deteriorating. To turn the tide, a filter of iron sand is being constructed on a large scale for the first time in the world. An innovative project under the European funding programme LIFE and the LIFE HELVEX project.
Update May 2020: A new milestone for the Groote Meer; the new purification work is ready for use! After decades of receiving water full of fertilisers from neighbouring agricultural plots, a purification work has now been installed. This purification work should give special plants such as sedges and bank weeds in the fen a chance again.
In March and April 2020, the crane operators of contractor Harteman from Tiel were busy excavating 18000 m3 of soil for the construction of a water buffer. Here, agricultural water from the Steertse Heide, which is rich in fertilisers, will be stored to then flow through the filter of iron sand. One of those fertilisers is phosphate, which is bound to the iron and thus no longer flows into the Groote Meer.
Natuurmonumenten supervised the preparation and realisation and was able to carry out this purification work together with Grenspark Kalmthoutse Heide, Waterschap Brabantse Delta, Provincie Noord-Brabant and Stad & Groen. The inflowing and outflowing water will be measured at several locations over the next few years. Thanks to these measurements, we will get a better picture of the phosphate loads flowing into the Groote Meer. This will allow us to assess the functioning of the filter and make adjustments if necessary.
In the fen, nutrient-poor water contributes to species diversity, as special plants are no longer overgrown by fast growers. As long as agriculture still has such an impact on water quality, this is a nice bridging solution.
The construction of the purification work is part of LIFE HELVEX, a European project to restore heathland, land dunes and fens and combat invasive exotic species. The province of North Brabant has co-financed the realisation of the purification work.
