A storage reservoir (16 km by 3.5 km) in the lowland valley of the unregulated Warta river, between Skêczniew and Warta towns. Meadows and pastures adjoin the reservoir near Proboszczowice and Dzierz¹¿na villages. Its shoreline is formed by natural valley slopes, side dams (which block the mouths of the Teleszyna and Pichna rivers), and also backwater dams, which limit the flooding area when the water-level is at its highest (maximum area is 4,200 ha). The reservoir bottom was not modified before flooding and, when the water-level is low (minimum area 1,700 ha), a varied terrain with scattered small hollows is exposed. The southern part of the reservoir, which floods only during times of high water, is occupied by a mosaic of meadows and willow Salix scrub with groups of partly dead trees. Highest water-levels are reached in April and May, followed by a slow fall.
A notable site for breeding and migrating waterbirds; breeding numbers vary from year to year, depending on the water-level. Breeding species of global conservation concern that do not meet IBA criteria: Crex crex (one pair, irregularly).
Pressure/threats to key biodiversity
Birds are disturbed by tourism/recreation. Lowering of the water-level too early in the season destroys many nests. The southern part of reservoir is a `silence zone', and is planned as a bird reserve (not yet designated).