Río Bayagán is a river in the municipality of Ponce, Puerto Rico.

This river extends from the mountains in Montes Llanos and gathers waters from the streams in the vicinity of 18.08908 North and 66.61629 West, in the area of Hacienda Usera.

Río Bayagán progresses in a southern direction through barrio Machuelo Arriba making its way southward until its mouth.

Roads are listed as the river flows from its origin in the mountains of Montes Llanos, north of the city of Ponce, to its merging with Rio Cerrillos in Barrio Machuelo Arriba to form Rio Bucana (N/A = Data not available): Bayagán is only six kilometers long.

[9] Like several other rivers in southern Puerto Rico, Río Bayagán flows perennially only during the rainy season.