The Jeziorsko Reservoir on the Warta River is the largest body of water in the Łódź Voivodeship, created in the 1980s for flood control and water retention purposes. Its surface area exceeds 40 km² when full and its length reaches approximately 17 km. The reservoir is an important bird habitat – it houses an ornithological reserve protecting herons, terns, and cormorants, among others (Jeziorsko Reserve and Nadwarciański Protected Landscape Area). It is also an excellent spot for observing sunsets and natural changes in the Warta Valley.