The Madawaska River is the largest tributary of the Ottawa River in the St. Lawrence River drainage basin in Ontario, Canada. The river is long and drains an area of . Its name comes from an Algonquian band of the region known as "Matouweskarini", meaning "people of the shallows".
The Madawaska River rises at Source Lake in geographic Canisbay Township in the Unorganized South Part of Nipissing District, in the highlands of southern Algonquin Park. It flows east, dropping before emptying into the Ottawa River at Arnprior.
The lower portion of the Madawaska River supports several large lakes, including:
Bark Lake and Kamaniskeg Lake devide the Madawaska river into three secions known as the Upper, Middle, and Lower Madawaska.
In the late 19th century, the river was used to transport logs from the forested areas surrounding the river. Beginning in the 1960s, the river was used to generate hydroelectric power. Undammed sections of the river are also used for canoeing, kayaking and recreational fishing.
Around 1916, artist Tom Thomson followed the log drive down the river and painted The Drive (1916-17).
The most common species of game fish found in this river include walleye (yellow pickerel), northern pike, muskellunge, smallmouth bass, and largemouth bass.
Ontario Power Generation (OPG) has 5 stations on the Madawaska.
In June 2002 sluice gates at the Barrett Chute Generating Station were accidentally opened, killing two people, and injuring seven. OPG and two employees were charged with criminal negligence. Procedures at the plant were reviewed, and fencing added or repaired.
The Calabogie station is being upgraded in 2022 to double capacity from 5 MW to 10 MW. The original station was badly damaged by a tornado in September 2018. Clean up was completed in 2020. The project is expected to cost 100 million dollars.
Two sections of the river are designated and protected as provincial waterway parks:
Both parks are administered by Ontario Parks but are non-operating, meaning there are no visitor facilities or services available. Both are ideal for whitewater canoeing.