The Cherven Bryag Municipality is located by the right side of the Iskar River which is a right tributary of the Danube and has a length of 368 km and is the longest river that runs entirely within Bulgaria.
The municipality is located by the right side of the Iskar River, close to the inlet of Zlatna Panega River. The Iskar (Bulgarian: , pronounced [iskr; Latin: Oescus) is a right tributary of the Danube. With a length of 368 km it is the longest river that runs entirely within Bulgaria. 
