Karst Lake in Kusięta

The small lake in Kusięta, in the Olsztyn municipality near Częstochowa, looks like an ordinary pond among meadows, but it is a geological rarity. It is the largest of a group of ponds that survive in karst sinkholes thanks to a layer of clay. According to the Silesian Tourist Organisation, these are the only features of their kind on the whole Kraków-Częstochowa Upland.

Water that should have vanished

In limestone karst, water usually drains away quickly into underground fissures and caves. In the Kusięta – Srocko – Małusy Wielkie area, however, the sinkholes filled up with poorly permeable clay deposits that limit seepage and let water stay on the surface. The lake is fed only by rain, so its level and size change noticeably with rainfall. Larger lakes of karst origin occur in Poland only in the southern part of Lublin Polesie.

What to see nearby

• Small sinkholes north-east of the lake – hollows a dozen or so metres across that fill with water only in wet periods. They trace the course of an underground cave system.
• The Koziniec uvala, about 400 m to the north-west – a narrow, elongated hollow about 220 m long with slopes up to 10–12 m high, formed when a cave roof collapsed or a chain of sinkholes merged. During heavy rain or snowmelt, water flows into it and disappears into its floor.
• Zielona Góra Nature Reserve – a limestone hill (342 m above sea level) protected since 1953, with a rock formation known as the Devil's Anvil. The Eagles' Nests Trail runs over the hill.

Tripto tips

• Today the lake is a fishing pond, and part of its shoreline has been altered by people – do not expect a wild, untouched lake.
• The Koziniec uvala is heavily overgrown with trees and shrubs, so it is hard to reach during the growing season. Karst features are easiest to see in early spring, after snowmelt or heavy rain.
• A quarter of an hour is enough for the lake itself. Combine it with a walk in Zielona Góra reserve or with the geological nature trail in Olsztyn (about 5 km, about 3 hours), which starts at the foot of Castle Hill.