The Zegrze Reservoir (or Zegrze Lake, in Polish officially Jezioro Zegrzyńskie, unofficially Zalew Zegrzyński) is a man-made reservoir in Poland, located just north of Warsaw, on the lower course of the Narew river. It is formed by a dam constructed in 1963 with a hydroelectric complex producing 20 megawatts of power. The surface area of the reservoir is about 33 km². The name originates from the nearby Zegrze village, featuring the historic Radziwiłł Palace (Pałac Zegrzyński) built in 1847 by the noble Krasiński family.