Šalčininkai District Municipality (Lithuanian: Šalčininkų rajonas, Polish: Gmina rejonowa Soleczniki) is one of 60 municipalities in Lithuania. It has one of biggest Polish minority populations in Lithuania, with 31,223 or over 80% (2001 census) of the population claiming Polish ethnicity. Šalčininkai is the largest town in and the administrative center of the district. The south-eastern border of the municipality with Belarus includes a distinctive salient of Lithuanian territory almost completely surrounded by Belarus. Lithuanian Route 104 passes through the district. The Poškonys Reservoir (Poškonių tvenkinys) with an area of 0.3 km2 on the Gauja River is located in the district.