About Jeziorsko Dam

The Jeziorsko reservoir on the Warta river in Łódź province holds 193.1 million cubic metres, making it the largest reservoir in central Poland. Completed in 1986, the low 14-metre earth embankment dam near Warta town creates an unusually shallow but extensive water body — the reservoir covers approximately 4,200 hectares with an average depth of only 3.4 metres, giving it a distinctly lake-like character. The primary purpose is flood control on the Warta and Ner rivers protecting the Sieradz and Kalisz regions, combined with water supply augmentation for industry and navigation. The shallow, nutrient-rich water body has become an internationally important wetland for migratory waterbirds: the Jeziorsko reservoir is designated as a Special Protection Area under the EU Birds Directive, with more than 230 recorded bird species. During spring and autumn migration, the extensive mudflats exposed by reservoir drawdown attract spectacular concentrations of waders, including rare species such as broad-billed sandpiper and white-rumped sandpiper. Breeding colonies include great cormorant, grey heron, common tern, and penduline tit. The reservoir is a popular angling destination and hosts national rowing competitions on its sheltered southern bays. Eutrophication management is ongoing due to agricultural nutrient inputs from the intensively farmed Warta catchment.