There are actually two distinct water bodies sharing the name "Rio Guaporé." The first is a small stream located in Rio Grande do Sul, in southern Brazil, flowing through a region known for its diverse freshwater fishing. The second — and far more significant — is the major Amazonian river that originates on the Parecis plateau in Mato Grosso at an elevation of approximately 631 meters (2,070 feet) and flows roughly 1,260 kilometers (780 miles) before emptying into the Mamoré River. Of this length, approximately 920 kilometers forms the international border between Brazil and Bolivia. The larger Guaporé is a clearwater right-bank tributary that drains the eastern Bolivian lowlands and the southern Brazilian Shield, carrying a mean annual discharge of approximately 2,100 m³/s. Its waters are notably clear compared to other rivers in the Madeira system, with a pH ranging between 6.3 and 6.8 — slightly acidic, characteristic of clearwater Amazonian systems. The river is part of the broader Madeira River basin, which ultimately drains into the Amazon River, and it crosses the eastern portion of the Beni savanna region. The Guaporé Biological Reserve, encompassing 615,771 hectares (approximately 1.5 million acres), borders the river and is fed by several tributaries including the São Miguel, Branco, São Simão, Massaco, and Colorado rivers.