town, Renfrew county, southeastern Ontario, Canada. It lies along the Chalk River near its mouth on the Ottawa River, 90 miles (145 km) northwest of Ottawa. The town was formed in 2000 by the amalgamation of Chalk River and several other adjacent communities and was renamed Laurentian Hills.

Chalk River was a small frontier settlement until after World War II, when it became the site of Canada's first nuclear (nuclear energy) reactor and of the Chalk River Nuclear Laboratory, one of several research and development centres operated by Atomic Energy of Canada, Limited, concerned with the peaceful uses of atomic energy. The Trans-Canada Highway and the main line of the Canadian Pacific Railway serve the town and Deep River, a residential community for persons working at the laboratory. Inc. 1954. Pop. (2006) 2,789.