The northern part of the river flows in a southwest direction, forming the border between the Lékoumou and Pool departments.

[1] In 1883 the Belgian Captain Edmond Hanssens established the post of Philippeville at the limit of the territories granted to Pierre Savorgnan de Brazza.

[2] The post was founded at the confluence of the Bouenza and Niari rivers on behalf of Belgian interests under the cover of the Haut Congo Study Committee.

[3] The operation was in response to a concern by king Leopold II of Belgium that the Portuguese might prevail in their claim to control the mouth of the Congo River.

In May 2007 President Denis Sassou Nguesso visited Moukoukoulou, where all four turbine generators had been rehabilitated at a cost of US$12 million, although work on transformers was still not complete.