The river Trešnjica springs on the southwest side of Povlen at a height of 1185 m, and flows into the Drina near Gornja Trešnjica at a height of 180 m.
The distinctly gorge-like valley of Trešnjica is partly canyon-like in appearance. In the middle course, it flows through a picturesque canyon close to 6 km long, which is cut in an 800-1000 m high area.
In the Trešnjica canyon, it receives the largest right tributaries - Sušica and Tribuća.
Tribuća is the richest tributary of Trešnjica, it is 7 km long and springs below Tornička Bobija.
With its lower course, it separates the Boškovac plateau from the Gornja Košljanska surface, building an almost impassable gorge attractive for mountaineers. The Trešnjica canyon is a natural asset of exceptional importance
which has been placed under protection in order to preserve the habitat of the population of the natural rarity of the griffon vulture, geomorphological forms with the river and valuable heritage. One of the most beautiful is the habitat for 17 pairs of eagles
a griffon vulture that is still the only one living in the Uvac canyon. They represent an endangered species that is threatened with extinction and environmentalists are doing everything to save them from extinction.
Rich in natural beauties and rarities, the settlement of Gornja Trešnjica is also the founder of education in this area with a primary school from 1836.
A trout pond and a number of mills were also built. The environment is rich in medicinal herbs and fruits, so this ecologically clean zone should be used for healthy recovery and rest.
Specific for the Trešnjica canyon is that every spring, young fish, the "queen" of the Drina, emerge from the Drina to the natural spawning ground.
A full-system California trout pond was built on the Trešnjica River. Application of modern technology based on the injection of liquid oxygen into water
it is unique in Serbia, which has tripled its annual production.