Grand Duke Guillaume Visits Kalborn Mill, Pearl Mussel Breeding Station in Our Valley

On Monday 2 June 2026, Grand Duke Guillaume paid an official visit to the Kalborn Mill and the Our Valley, at the invitation of the Hëllef fir d'Natur Foundation within the context of preserving biodiversity and protecting natural environments in Luxembourg.

Grand Duke Guillaume was welcomed by Patrick Losch, President of the Hëllef fir d'Natur Foundation, and Frankie Thielen, Director of the Foundation, as well as by Georges Keipes, Mayor of Clervaux.

The Kalborn Mill: An exceptional site in the heart of the Natura 2000 area

Located in the upper Our valley, within the Our Nature Park and the Natura 2000 site "Our Valley," the Kalborn Mill, owned by the Hëllef fir d’Natur Foundation, is one of the Grand Duchy's natural gems. This site, at the confluence of the Luxembourg, Belgian and German borders, is home to some of the rarest and most endangered aquatic species in Europe.

Acquired in 1997 thanks to the Foundation's donors, the 3.3-hectare site was initially the subject of numerous development projects, all of which were ultimately abandoned due to a lack of funding. In 1999, an initial rehabilitation project with educational, scientific and ecological missions took shape, before the buildings were listed as national monuments in 2001.

In 2005, the Life-Nature project “Restoration of Freshwater Pearl Mussel Populations in the Ardennes,” co-financed by the European Union, finally gave concrete form to the mill. This culminated in the official inauguration of the freshwater pearl mussel breeding station on 26 September 2008.

The Freshwater Pearl Mussel Breeding Station

At the heart of the visit, the freshwater pearl mussel (Margaritifera margaritifera) breeding station held the full attention of the Grand Duke. An emblematic and endangered species, with more than 90% of the European population having disappeared during the 20th century, the freshwater pearl mussel now survives in Luxembourg only in the Our River.

Stefan Fernandes, Michel Frisch and Clemens Reuter presented the breeding techniques implemented since 2005, based on a refined Czech method, aimed at massively rejuvenating the mussel population before their reintroduction into the Our River in Belgium and Germany.

The Water Discovery Centre (WEZ): Discovering Aquatic Environments

The Water Discovery Centre (WEZ – Waasser Erliefnes Zenter), located in the old mill, is a leading educational resource for school groups, students and university researchers. The Grand Duke was able to appreciate the programmes implemented to raise awareness among young and old about the importance of water quality and aquatic biodiversity in the Our Valley.

The first research station in northern Luxembourg, the WEZ hosts university and scientific teams from across Europe to conduct research on this unique ecosystem.

Hike in the Our Valley: The Foundation's Land

The visit continued with a hike along the Our Valley, allowing the Grand Duke to discover the land acquired and managed by the Foundation in this area. Three stops punctuated the route:

- The old Moulin dam, with explanations on the concept of "free-flowing rivers" and the importance of ecological continuity in waterways;

- The Jansschlederbaach stream, focusing on the fish population and the rich ichthyological diversity of these waterways;

- The Foundation's land in the Our Valley, presented by Claude Schiltz, Head of Acquisitions for the Hëllef fir d’Natur Foundation, illustrating the land conservation policy implemented for decades.

A Shared Commitment to Luxembourg's Nature

The visit concluded at the Schelsbaach stream with words of thanks from Patrick Losch, followed by an address from Serge Wilms, Minister of the Environment, Climate and Biodiversity. The Foundation presented His Royal Highness with a symbolic basket, before the Municipality of Clervaux invited the participants to a friendly reception.

According to Hëllef fir d'Natur, this visit demonstrates the Grand Ducal House's commitment to supporting those involved in nature conservation and continues the interest shown by Grand Duke Henri in the Kalborn Mill site, which he visited in 2018. It sends a strong message to the Hëllef fir d'Natur Foundation and its 33 employees, who are dedicated to protecting the Grand Duchy's natural heritage.