Tolminka Springs deep in the Triglav National Park in the valley Polog. The river carved it's way towards Soča through a steep valley, a gorge at places, finaly opening up a bit when it reaches the Tolmin basin. From spring to confluence with Soča it runs for 10,2 km. The whole stretch is fishing water with the exception of the Tolmin gorge regional park. You can find all the species of trout and also grayling in the lower part.

Its uppermost part is managed by the Fisheries Research Institute of Slovenia. From Čezsoča to the confluence with Vogeršček, under the dam at Podselo its managed by the Angling club of Tolmin.