It is formed as a stream at the water spring from Tambarón, in the town of Montrondo, which falls within the Municipality of Murias de Paredes) and ends when its waters converge with the Luna River, forming the Órbigo River.

According to tradition, the name of the river comes from the name that the Romans gave to the inhabitants of the region it crosses: homus manium or "godmen", due to their hardness and resistance.

[1] Eutimio Martino [es] however considers that the name of the river comes from Aqua Mania,[2] interpretation consistent with other hydronyms of the northern peninsula.

In 2010 the Duro Hydrographic Confederation invested nearly 120,000 euros to improve the riverbed and alleviate the effects of floods.

[6] In the past there was a project to create a 200,000,000 m3 (7.1×109 cu ft) swamp, but all attempts to carry it out have met with opposition from affected locals and environmental groups.