The Upper Sûre reservoir also known as the Stauséi, has become one of Luxembourg's most popular summer destinations, and the record-breaking summer heat has only intensified the trend.
For ranger Tom Schmit, there is little doubt that 2026 could turn out to be a record year. Whenever temperatures push above 30°C in particular, the Stauséi becomes the number one destination for many in the Greater Region. "And then that leads to chaos, the municipality of Esch-sur-Sûre is aware of that, and the villages are burdened with that too", he said. That, he explained, is why a parking guidance system was rolled out several years ago, allowing visitors to know, as they would in the capital for example, how many parking spaces are still free.
The flood of visitors, however, brings its own set of problems. Cars parked wherever there is space, litter and noise all weigh increasingly on nature and on residents. In the ranger's view, the reservoir is already brushing up against the limits of what the nature reserve can absorb.
In the past, he pointed out, it was mainly locals who knew the loveliest spots. Today those places are shared, tagged and easily tracked down via social media and Google Maps, which has turned previously quieter corners into busy hotspots. "But there are no quiet places around the reservoir anymore", he noted. Locals, he added, tend to steer clear of the lake during the peak season, because they know what awaits them. Most visitors now come from the south of the country or from the wider Greater Region, whether "Germany, from Belgium, from France, from the city, from Capellen and so on".
For Schmit, the most dangerous kind of misconduct is still fire. "If we look online today, there are fires everywhere. And that is absolutely to be avoided around the reservoir", he said. The Stauséi supplies around half of Luxembourg's drinking water, which is why all open flames and barbecues are strictly banned along the shoreline.
Noise from music is another major concern, since sound carries across the entire lake and disturbs both visitors and wildlife. Increasingly, he added, that noise is also becoming mobile. People are taking to the water on stand-up paddleboards and playing music there too. "And that indirectly disturbs the people on the beaches and of course the birds that are breeding everywhere (...) So we clearly have a footprint there that we do not want."
Schmit is a ranger, not a police officer, and cannot hand out sanctions. His main task is to carry conversations and explain why certain rules are in place. He does not always manage to bring people round, but for him what matters are the exchanges that do land. "But if there is a real change in behaviour once in five, ten times, then in my opinion that's already something." Some visitors, he acknowledged, deliberately flout the rules. Others, particularly day-trippers from abroad, genuinely do not know any better.
Many visitors are also unaware that the reservoir is one of the country's most important sources of drinking water, providing "50% of our drinking water", Schmit noted. Once that penny drops, people often start to rethink how they behave. For Schmit, raising awareness is the single most important lever for protecting nature and safeguarding the country's drinking water over the long term.
