The Trois Saumons Est river flows through the municipalities of Saint-Damase-de-L'Islet and Saint-Aubert, in the L'Islet Regional County Municipality, in the administrative region of Chaudière-Appalaches, in Quebec, in Canada.

The Trois Saumons Est river has its source on the eastern slope of the mountain designated "Le Pain de Sucre" which overlooks the eastern part of Trois Saumons lake (length: 5.5 kilometres (3.4 mi); altitude: 434 metres (1,424 ft)), located in the municipality of Saint-Aubert.

[1] From its source, the Trois Saumons Est River flows over 18.2 kilometres (11.3 mi).

This confluence is located 1.7 kilometres (1.1 mi) southeast of the center from the village of Saint-Aubert and 7.1 kilometres (4.4 mi) to the south-east of the center of the village of Saint-Jean-Port-Joli.

[1] The toponym Rivière Trois Saumons Est was formalized on December 5, 1968, at the Commission de toponymie du Québec.