Whitemouth Lake feeds the river year round, along with many wetlands throughout the Sandilands Provincial Forest area.

The river runs north and crosses the Trans-Canada Highway where it enters an area of farmlands.

[4][5] There are twelve navigable whitewater features along the river, most rated Class I or II.

[4] The Whitemouth River has the non-parasitic, native species northern brook lamprey.

[6] Almost the entire Canadian population of the nationally endangered carmine shiner is found within this river.