Trinational Action Days 2025

Joining forces to manage Himalayan balsam in the Geul catchment

The catchment of the Geul with both action locations

Also in 2025, the Three-Countries Park, in collaboration with partners from the Working Group on Invasive Species, organized two cross-border action days against Himalayan balsam (Impatiens glandulifera):

(1) in Cottessen (NL) along the Geul, in a nature reserve managed by Het Limburgs Landschap and

(2) in Bildchen (DE) along the Tüljebach, under the guidance of the NABU-Naturschutzstation Aachen und Contrat de Rivière Meuse-Aval.

Both locations are situated in the Geul river basin, which extends through numerous political borders in the heart of the Euregio Meuse-Rhine. Since Himalayan balsam spreads especially along riverbanks, cross-border cooperation between upstream and downstream areas along the Geul is of great importance.

Himalayan balsam is listed on the European list of invasive species that are to be controlled. Invasive species pose a threat to biodiversity. Additionally, Himalayan balsam spreads particularly strongly in source areas and along riverbanks. Due to its shallow roots, it cannot anchor the soil sufficiently, which exposes vegetated riverbanks to a high risk of erosion. Given the increasing heavy rainfall, this poses a serious problem for flood protection.

Effective and sustainable management of Himalayan balsam requires systematic control as well as continuous monitoring in the field over several years. Therefore, within the framework of the Working Group on Invasive Species, further trinational action days will also be organized in the coming years.

12/6/2025: Trinational Action Day at Cottessen (NL)

On June 12, 2025, a trinational action day against Himalayan balsam took place in Cottessen (NL) at the Belgian-Dutch border. The field event was organized under the leadership of Het Limburgs Landschap, while the coordination and planning in advance were handled by the Three-Countries Park.

The action focused on a nature reserve managed by Het Limburgs Landschap, located in close proximity to the Geul. Active measures against Himalayan balsam have been underway here since 2024. The control efforts at the downstream section of the Geul on the Dutch side were only made possible after systematic action had been taken in previous years against this invasive plant species at the upstream section on the Belgian side. Since the balsam primarily spreads through its seeds along rivers, effective control along a waterway is only feasible with close coordination between upstream and downstream areas – in this case, even across borders.

On this action day, a total of 12 international "activists" came together: 7 from Germany, 2 from Belgium, and 3 from the Netherlands. Together, they uprooted and removed newly emerging balsam from the area over a period of 4 hours. However, it will still take several years before the area is completely free from this invasive plant species.

7/7/2025: Trinational Action Day at Bildchen (DE)

The action day took place on July 7, 2025, at the German-Belgian border near Bildchen. Around 15 participants from Germany, Belgium, and the Netherlands worked under the guidance of the NABU-Naturschutsstation Aachen and the Contrat de Rivière Meuse-Aval to combat the Himalayan balsam in the Tüljebach's source area.

Active efforts against the balsam have been ongoing at this location for three years. During the Trinational Action Day in 2024, coordinated efforts were already made to tackle this invasive plant species.

The Tüljebach is a strategically important site for cross-border cooperation, as it initially flows from Germany into Belgium, where it joins the Geul at Kelmis. The Geul then flows from Belgium into the Netherlands and eventually empties into the Meuse at Meerssen. Thus, the control of the balsam at Bildchen on the German side also impacts its presence in Belgium and the Netherlands, highlighting the importance of cross-border collaboration.