Bajer is a water catchment below the village Potoki in the valley of Rožni dol. The name Potoki (Potoki = Streams) suggests this is a place of streams and springs. The stream was dammed at Bajer and its water used for steam locomotives. Near Bajer the entrance to the Semič railway tunnel is located, the longest single-track tunnel in Slovenia (1975 m).

The entire area of Bajer is one of the largest wetlands in Semič municipality. A large collection of streams springs and the accumulation of water has created ideal conditions for animal and plant life. Bajer is considered a true paradise for amphibians. The most common is the toad, the Yellow-bellied Toad, the Edible frog, and the salamander. The stone crayfish also has its habitat here, together with various bugs, snails, worms, etc. Years ago, an experiment showed that the water from Bajer flows into the Krupa river through underground waterways and contributes to Krupa.