Lake Sieniawskie is an artificial reservoir, which was established in 1978, when the Wisłok River was separated by a dam at the level ofSieniawa town.
The lake has an area of almost 1.3 km², a capacity of approx. 14.2 million m³ (including approx. 4.4 million m³ flood reserve) and a maximum depth of approx. 29 m. The water is accessed by a concrete dam, 174 m long, 38 m high and 8.5 m wide in the crown. The regional road number 889 from Rymanów to Szczawny passes at the crown of the dam. The dam contains the water intake for the Rymanów and Iwonicz Zdrój spas as well as a small hydropower plant. In addition to supply function, the reservoir also has anti-flood, retention and recreational functions. There are no fish passes in the dam but lake is systematically stocked. You can catch carp, pike, chub, zander, perch and catfish, among others.
Along the lake leads the green trail from Besko to Kanasiówka (823 m a. s. l.).