The Rivière des Mères (French pronunciation: [ʁivjɛʁ de mɛʁ]) is a tributary of the south shore of the Saint Lawrence River.

The water level of the river varies with the seasons and the precipitation; the spring flood occurs in March or April.

The Rivière des Mères rises on the northwest side of the railway, in the 3th rang west, in Saint-Michel-de-Bellechasse.

The name of this watercourse evokes the work of the Augustine sisters of the General Hospital of Quebec, who owned the seigneury of Saint-Vallier.

The toponym Rivière des Mères was formalized on December 5, 1968 at the Commission de toponymie du Québec.