The Grand lac Saint-François (French pronunciation: [ɡʁɑ̃ lak sɛ̃ fʁɑ̃swa]) is a freshwater body covering 51-square-kilometre (20 sq mi), in the administrative region of Chaudière-Appalaches, in southeastern Quebec, in Canada.

This river flows a priori for 10.7 km towards the southwest to join Lake Aylmer at Disraeli, which the current crosses to head south.

It was renamed to avoid confusion with Petit lac Saint-François (Ashberham) which is located 1.5 km northwest of it.

[2] In 1815, the vast territory where the lake is located was not yet surveyed as mentioned by Joseph Bouchette in his book “Description topographique du Bas-Canada”.

formalized by the Commission de toponymie du Québec replacing the designation "Lac Saint-François".