About Debe Dam

The Dębe reservoir on the Bug river in Masovia holds 96 million cubic metres and was completed in 1963 — one of the first large reservoirs built in People's Republic of Poland after the Second World War. The 17-metre concrete and earthfill weir dam at Dębe village north of Warsaw on the Narew river (which carries Bug river water at this confluence) creates a shallow, meandering reservoir that extends some 30 kilometres upstream. The Dębe reservoir forms the upper element of the Zegrzyński reservoir system, which serves as the primary backup drinking water source for the Warsaw metropolitan area. Its main functions are water supply regulation, flood attenuation on the Narew-Bug system, and hydroelectric generation of approximately 5 megawatts. The reservoir — known locally as the Zalew Zegrzyński — is extremely popular for recreation given its proximity to Warsaw: sailing clubs, water skiing, rowing, beach areas, and weekend cottages line the extensive shoreline, and it is estimated to receive over one million visitor days per year. Water quality management is challenging: intensive recreation, agricultural runoff from the Bug catchment, and treated wastewater inputs create eutrophic conditions with frequent algal blooms in summer. Cyanobacterial warnings are issued most summers, temporarily restricting swimming access.