river in Outaouais region, southwestern Quebec province, Canada. The river rises in a chain of lakes north of Baskatong Reservoir and flows generally southward for 240 miles (390 km) to join the Ottawa River at Hull. It was named for Nicolas Gatineau, a fur trader who is reputed to have drowned there about 1683. Having once served for centuries as a major artery for the lumber trade, the Gatineau became an important source of hydroelectric power in the 20th century.