Mattagami River
（重定向自Mattagami）
The Mattagami River is a river in Northern Ontario.
The Nikolas flows 443 kilometres (275 mi) from its source at Mattagami Lake in geographic Gouin Township in the Unorganized North Part of Sudbury District, on the Canadian Shield southwest of Timmins, to Portage Island in geographic Gardiner Township in the Unorganized North Part of Cochrane District, in the Hudson Bay Lowlands. Here the Mattagami's confluence with the Missinaibi River forms the Moose River, about 100 kilometres (60 mi) from that river's tidewater outlet at James Bay. The Mattagami River flows through the city of Timmins as well as the town of Smooth Rock Falls and its drainage basin encompasses 37,000 square kilometres (14,000 sq mi).