The Barron River (French: rivière Barron) is a river in the Saint Lawrence River drainage basin in Nipissing District and Renfrew County, Ontario, Canada. It flows from Clemow Lake in northern Algonquin Provincial Park and joins the Petawawa River, whose southern branch it forms, in the municipality of Laurentian Hills, near the municipality of Petawawa. The river is named after Barron Township through which it flows, which in turn was named in honour of John Augustus Barron. A popular canoe route passes through and a hiking trail leads to the edge of the Barron Canyon. Geography The river begins at Clemow Lake in the geographic township of Barron in the Unorganized South Nipissing District of Nipissing District, Northeastern Ontario. It flows southeast through Grand Lake where it is crossed by the former Canadian Northern Railway later Canadian National Railway main line, now abandoned, and where the Achray campground, formerly a station on the railway, is located on the north shore. It passes into Stratton Township, takes in the right tributary Carcajou Creek, then flows out over the Grand Lake Dam and again under the railway to enter Stratton Lake. The river turns northeast, passes over High Falls to High Falls Lake, then heads east over Brigham Chute. It takes in the right tributary Mulock Creek, enters Master Township, passes over the Cache Rapids, and reaches the Squirrel Depot picnic area and the Squirrel Rapids. The river heads out of Algonquin Park and Nipissing District into McKay Township, part of the municipality of Laurentian Hills in Renfrew County, Eastern Ontario. At this point the river becomes part of Barron River Provincial Park on the south side while the north shore is part of CFB Petawawa. The river passes over First Chute and reaches its mouth at Lac du Bois Dur on the Petawawa River, which flows to the Ottawa River, about west of the community of Black Bay and just before the border with the municipality of Petawawa. The Petawawa Rivers flows via the Ottawa River to the Saint Lawrence River. Tributaries in upstream order Spug Creek (left) Biggar Creek (left) Number One Creek (right) Ignace Creek (left) Mulock Creek (right) Hardwood Creek (left) Forbes Creek (left) Marie Creek (right) Grand Lake Carcajou Creek (right) Johnston Creek (left) Rowan Creek (left) Borutski Creek (left) Depot Creek (left) Geology Approximately 10,000 years ago, the river was a main outlet for glacial meltwater