The source of the Breg is considered geographical source of the Danube and is a listed building
The Breg is with 46 km the longest and richest source of the Danube river and runs through the south-east of the Black Forest and Baar.
It rises 1078 m above sea level. NN height six kilometers north-west of Furtwangen. Your source close to the Martin's Chapel, also called Source of the Danube, is protected as a natural monument. It is located approximately 100 meters southeast of the watershed Rhine / Danube ( the major European watershed ). Beyond that, however, only about 900 meters away, springs the Elz River, opposite in the same longitudinal Talung initially flows north and later flows into the Rhine.
The Bregtal section is called the top, Katzensteig significantly by Ice Age glaciers shaped valley with strikingly low gradient and with a landscape that is characterized by large Black Forest farms. Between the towns of Furtwangen and Vohrenbach the Breg flows in a broader and somewhat more densely populated valley to the east, then, generally directed to the southeast to flow through a lonely forest valley, accompanied by a road and the route of the former Bregtalbahn, which today uses a bike path. Shortly before Hammereisenbach - Bregenbach lead the Linach below their Linachtalsperre and in place then the largest Breg inflow Eisenbach, empties in the Braeunlingen Röthenbach with the Kirnbergsee. There and on about Huefingen to Donaueschingen Breg already flows outside of the Black Forest by a broad, open valley in the high area of Baar.
After 45.9 kilometers, the Breg in Donaueschingen flows from the right with the Brigach the Danube together - mnemonic: Brigach and Breg the Danube feeder path. Since the Breg to be out of her longest river source, is also equipped with a catchment area of 291.2 km ², the most water source of the Danube river, its source hydrographic origin as the Danube (Donau source) is considered.
- Schützenbach (left)
- Rear Breg (right)
- Rohrbach (left)
- Langenbach (left)
- Linach (right)
- Eisenbach (right)
- Forbach (left)
- Kohldobelbächle (left)
- Reichenbächle (right)
- Pond Brook (left)
- Landgraben (right)
- Röthenbach (right)
A more extensive list, which also includes small tributaries, is found in the list of tributaries of the Brigach and Breg.