There are two river basins in Slovenia.
The Adriatic rivers river basin which consists of rivers like the Soča and its tributaries, the Reka (which flows partially underground) and the Rizana. This system is the native range of Salmo Marmoratus. Thymallus Thymallus of the Adriatic lineage are native to the Soča and its tributaries.
The Danube River basin which has major rivers like the Sava, the Drava and the Mura. The Danube system is the native range of Hucho Hucho which is found in the larger rivers and the Salmo Trutta of the Danubian lineage
to find the individual rivers in this system and who manages the rivers go to the:
Adriatic rivers river basin of Slovenia.
Danube river basin of Slovenia.