Lake Caniapiscau (the approved Inuit spelling is Kaniapiskau) is a large lake in the centre of the Canadian province of Québec.

The lake was formed about nine thousand years ago as glaciers left Québec after having scoured the Canadian Shield for ninety thousand years. As post-glacial rebound elevated the southern part of the Shield more rapidly than the north, the drainage of the lake became permanently northward into the Caniapiscau River and ultimately Ungava Bay. The prototype of the present lake was an ice dam that drained southwards into the Gulf of Saint Lawrence whilst Nunavik was still glaciated. Presently the lake fills a depression in the highest part of the Canadian Shield, so that few streams flow into it.

The lake shore is vegetated entirely with taiga. It is in the zone of discontinuous permafrost, but is still accessible only by bush plane, even during the summer when it is not frozen.

Lake Caniapiscau has been expanded to about four times its original size by hydroelectric projects that capture water from rivers further south and move them into rivers flowing into James Bay.

See also

• Hydro-Québec
• James Bay Project
• La Grande River
• List of Quebec rivers