Beneath the surface of Alsace, in the abandoned galleries of the former Stocamine potash mine, 42,000 tons of industrial waste—containing toxic substances like arsenic, mercury, and cyanide—have been stored since the 1990s. This waste lies under the Rhine groundwater aquifer, a critical source of drinking water for millions of people in the region. In 2002, a fire and the subsequent collapse of parts of the mine led to a court decision in Strasbourg that approved the permanent containment of the site. This decision rejected appeals from environmental groups and the European Collectivity of Alsace, even as some lawmakers have pushed for the removal of the most hazardous materials. The Stocamine site was originally intended as a temporary storage facility for highly toxic industrial waste, using the stability of the old potash mine to hold the waste until safer disposal methods could be developed. However, the 2002 fire exposed the vulnerability of the site, causing parts of the mine to collapse and making the waste inaccessible. Over time, the planned retrieval of the waste became increasingly difficult due to technical and financial challenges, turning what was meant to be a 30-year temporary solution into a permanent storage problem. The galleries where the waste is stored are gradually closing in due to the pressure of the surrounding rock—a natural process common in potash mines. A prior hydrogeological study had warned that long-term storage posed a risk to the quality of the Rhine groundwater, which is the largest freshwater reserve in Europe and spans parts of Alsace and Germany. Concerns remain that if water were to seep into the collapsed galleries, it could become contaminated with the toxic waste, leading to pollution that would be nearly impossible to stop once it started. In 2017, a government decree allowed for the indefinite storage of the waste, but this was later overturned by an administrative court in Nancy, which criticized the legal basis for the decision. The government then secured the site through a financial guarantee provided to the company managing the site, effectively halting any further discussion about retrieving the waste. In late 2024, a bipartisan amendment proposed allocating 31 million euros to remove the most dangerous waste, while another amendment from the LFI party called for continued efforts to address the toxic legacy. However, the Strasbourg court ultimately upheld the decision to keep the waste permanently sealed. Although the government technically retains the right to suspend the confinement, this has not reassured local officials, who continue to demand a re-evaluation of retrieval options based on the precautionary principle. The situation highlights a deep societal and political divide, with the waste remaining buried under the rock and the aquifer, largely out of public view and discussion.