Wikipedia
Jääsjärvi
Jääsjärvi is a medium-sized lake of Finland. It is located in Hartola and Joutsa municipalities, in the regions Central Finland and Päijänne Tavastia. The water quality in the lake is excellent. The river Tainionvirta has its source in Jääsjärvi. Jääsjärvi flows through it and with several smaller lakes to Päijänne. Water in Jääsjärvi is bright. Lake is part of Sysmä catchment area and Kymijoki main catchment area.
There is dozens of islands in the lake. Biggest lakes are Vehkasalo, Hirtesalo, Kotisalo, Ohrasaari, Urrionsaari and Nautsalo. Vehkasalo, Hirtesalo and Ohrasaari are islands with road connection.
In winter time, lake typically gets frozen.