The environmental impacts of mining, especially regarding water, are a highly topical issue. However, historical studies on environmental vulnerabilities caused by mining industries are lacking. This article seeks to provide a historical highlight on the vulnerability to flooding in the Couchant de Mons coal basin. The Haine valley case is interesting because the effects of mining works on the water regime are old but it is from the 1880s onwards that the problem became crucial for the future of the region. The valley has undergone many floods between the 1880s and the 1940s, which is the period of intensive extraction of coal. Quickly, the collieries are accused of engendering these floods, or, at least, increasing their effects, because of the mining subsidence created by mining underground works. The intensive extraction of coal for six decades is the cause of the vulnerability of the valley to flood risk. These effects are still perceptible now. Yet, collieries were not involved in rivers landscaping projects. The Belgian State accepted even to carry on the burden of rivers landscaping works and the management of collapsed areas without involving the collieries at all. How to explain this “disjunction of responsibility” in the risk management to flooding in the Haine valley ? The purpose of this article is to understand how collieries have managed to convince government that subsidence engendered by their works doesn’t play the main role in the floods hitting the Borinage, mainly by studying the acts and discourses of the Committee of the Haine, a pressure group created by the collieries in 1925 following the disastrous floods of winters 1924-1926.