It is a left tributary of the Paracauari River, which enters the Atlantic at Soure, Pará.

The mangroves of the left (east) bank of the Saco are protected by the Soure Marine Extractive Reserve.

This covers 27,464 hectares (67,870 acres) of typical mangroves forest and tidal waters.

[1] The riverine Manguezal do Rio do Saco section has an area of about 3,534 hectares (8,730 acres).

This article related to a river in Pará, Brazil is a stub.