Black Water

The Eau Noire is a source river of the Viroin that springs at Cul-des-Sarts in the far south of the province of Namur at an elevation of 350 meters. Shortly after the source, it forms the border with France for about five kilometers before bending northward. Just past Couvin, the main town along the river, part of the river runs underground through the Grottes de Neptune, also known as the "Grottes de l'Adugeoir." The underground branch merges with the main stream again at Nismes. At the "Roche à Lomme," the Eau Noire merges at an elevation of 150 meters with the Eau Blanche to form the Viroin.
In early 1978, the residents of the region faced plans to build a 70-meter high dam on the river, just before it reached Couvin. This would completely flood the valley of the Eau Noire and two tributaries. Immediately, a protest movement arose against the project, which was both playful but sometimes also violent. For instance, the Ministry of Public Works in Brussels was occupied, some excavators were sabotaged, and the construction site building was destroyed twice. To publicize their actions, an illegal radio station was also set up, broadcasting from the forests around Couvin and moving for each broadcast. Following the destructions, a judicial investigation was launched in which several activists were arrested and interrogated for a long time. However, no trial ever took place. By the end of the year, the project was suspended, pressured by the protests but also because, as the local residents had always claimed, the ground was too unstable for the construction of such a dam. The suspension ultimately turned out to be the definitive end of the plans.

Wikipedia