Which river has the Negro River as a tributary?

Recently, the Negro River, a major Amazonian tributary, fell to its lowest level in 122 years. In terms of discharge, it is among the biggest rivers in the world and one of the Amazon River's biggest tributaries. It begins in eastern Colombia and travels through Venezuela, Brazil, and Colombia before joining the Amazon in Manaus. The river is roughly 1,400 kilometres long, of which 850 are in Brazil. The river's black water, which was caused by tannins and decomposing organic waste, earned it the moniker "Negro." It is the biggest blackwater river in the world. It is surrounded by a massive protected area called the Central Amazon Ecological Corridor.