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On Friday 26 June 2026, Luxembourg’s Water Management Administration (AGE) warned that the ongoing heatwave has caused a critical drop in dissolved oxygen levels in the country's rivers, posing a serious threat to aquatic ecosystems and increasing the likelihood of local fish deaths if conditions do not improve.
According to the AGE, the exceptionally high temperatures currently being observed have led to a significant deterioration of conditions in Luxembourg's watercourses, in particular a critical decrease in the level of dissolved oxygen, which is essential for the survival of aquatic wildlife.
River temperatures have increased very rapidly for this time of year. At some measuring stations, values above 25°C have already been recorded, representing a particularly high level of warming for Luxembourg's aquatic ecosystems.
Under these conditions, the decrease in dissolved oxygen levels directly affects aquatic organisms. Fish are particularly vulnerable and local fish mortality is highly likely if the situation persists.
As a result, AGE said it continues to monitor the development of the situation closely and calls on all stakeholders concerned, in particular sanitation syndicates, industries and establishments carrying out direct discharges into watercourses, to take preventive measures adapted to the current fragility of aquatic ecosystems.
Furthermore, water abstraction currently authorised remains possible in compliance with the conditions laid down in the authorisations in force, said AGE adding that it urges all users to use water sources in moderation.
If river levels continue to fall over the coming days, the authorities may introduce a temporary nationwide ban on taking water from rivers, AGE stressed.
The AGE said restoring rivers to a good ecological condition would help them better withstand extreme heat and low oxygen levels. It noted that rivers which have undergone renaturation are more resilient during heatwaves.
The administration also highlighted the government's ongoing efforts to speed up river renaturation projects. Since Environment, Climate and Biodiversity Minister Serge Wilmes launched the first "Renaturéierungsdësch" round table in November 2025, working groups have been developing proposals to improve the quality and resilience of Luxembourg's waterways.
The AGE said it will continue to monitor the situation and keep the public informed. It also encouraged everyone to use water responsibly during the current heatwave.
River water levels can be monitored at www.inondations.lu.
