[10] The Branco flows nearly south, and finds its way into the Negro through several channels and a chain of lagoons similar to those of the latter river.

[5] As suggested by its name, the Branco (literally "white" in Portuguese) has whitish water that may appear almost milky due to the inorganic sediments it carries.

Alexander von Humboldt attributed the color to the presence of silicates in the water, principally mica and talc.

The Rio Negro is a blackwater river with dark tea-colored acidic water (pH 3.5–4.5) that contains high levels of dissolved organic carbon.

[15] Until approximately 20,000 years ago the headwaters of the Branco River flowed not into the Amazon, but via the Takutu Graben in the Rupununi area of Guyana towards the Caribbean.