Somenos Lake is a small shallow water body located in the Municipality of North Cowichan on Southeast Vancouver Island.

The lake is drained near its southern extremity by Somenos Creek which flows southeast approximately 4 kilometres (2.5 mi) to the Cowichan River.

The Lake also contains populations of native Brown Bullhead (Ameiurus nebulosus), Three-Spined Stickleback (Gasterosteus aculeatus), and Peamouth Chub (Mylocheilus caurinus).

Of particular interest to conservation is the large number of Trumpeter Swans (Cygnus buccinator) that arrive at Somenos Lake in October and remain until early April.

The decay of the highly productive cyanobacteria also generates anoxic conditions in the water column which severely limits habitat for trout and salmon.