The shape of this lake is very complex, because the banks form many peninsulas, in its periphery of more than 420 kilometres (260 mi).

Several streams feed Lake Manouane, including the rivière des Montagnes Blanches.

This dam development made it possible to create a reservoir to control the water supply of the hydroelectric plants located downstream on the Péribonka River.The mouth of Lake Manouane is located on the southeast shore, at: From the mouth of Manouane Lake, the current flows southward on the Manouane River, on 143.3 kilometres (89.0 mi) southerly the course of the Péribonka River, crosses Lac Saint-Jean East on 29.3 kilometres (18.2 mi), and then on 155 kilometres (96 mi) the course of the Saguenay River east to Tadoussac where it meets with the St. Lawrence River.

The designation is of Montagnais origin, Manauan Shakaika meaning "lake where we collect eggs".

[3] The toponym Lake Manouane was formalized on December 5, 1968 at the Bank of Place Names of the Commission de toponymie du Québec.