About Dzierzno-Duze Dam

The Dzierżno Duże reservoir on the Kłodnica river in Upper Silesia holds 84.3 million cubic metres and occupies an unusual setting — a man-made reservoir in one of Europe's most heavily industrialised landscapes. Completed in 1963, the 16-metre earth embankment dam near Pyskowice in the Silesian Metropolis GZM impounds the Kłodnica river, which drains the heart of the Upper Silesian Coal Basin. The reservoir was built for industrial water supply to the steelworks and chemical industry of Gliwice and Zabrze, and for flood control on the heavily modified Kłodnica. Its history is intertwined with the industrial transformation of Upper Silesia: during the communist era it supplied massive volumes of process water to heavy industry, and its water quality reflected severe industrial pollution. Since the post-1989 industrial restructuring and closure of many polluting facilities, water quality has improved substantially, though legacy contamination of sediments remains a concern. Today the Dzierżno Duże is primarily a recreational reservoir serving the dense population of the Silesian Metropolis: sailing, angling, and beach activities are popular on the northern shores near Pyskowice, and the adjacent Dzierżno Małe reservoir provides additional recreation space. The water body is an important stop for migratory waterbirds moving through the otherwise heavily built-up Silesian landscape.