[2] The river flows in a generally southeast direction and empties into the Gulf of St. Lawrence near the Gros Mécatina Archipelago, west of the Baie des Moutons and the village of Mutton Bay.

[3] The Gros Mécatina Archipelago is in the Gulf to the southeast of the point at the river's mouth.

[1] The river basin includes parts of the unorganized territory Petit-Mécatina and the municipalities of Côte-Nord-du-Golfe-du-Saint-Laurent and Gros-Mécatina.

[7] The qualifiers Petit and Gros (Small and Big) were used to distinguish two nearby trading posts in the 18th century.

[7] The proposed Harrington Harbor Biodiversity Reserve would lie in the river's watershed.

[11] The river exceeded its target for salmon management in 2018, and in July 2018 the Ministry of Forests, Wildlife and Parks announced that in August anglers could keep their catch of one large salmon 63 centimetres (25 in) or longer in the Gros Mécatina, Napetipi, Saint-Paul, Vieux Fort and Matapedia rivers.