Mattagami River

Last updated
Mattagami River
Rivière Mattagami(in French)
Smooth Rock Falls mill.JPG
Mattagami River at Smooth Rock Falls
Mattagami River
Etymology Ojibwe language
Location
Country Canada
Province Ontario
Region Northeastern Ontario
Districts
Physical characteristics
SourceMattagami Lake
 • locationGouin Township, Sudbury District
 • coordinates 48°00′46″N81°33′28″W / 48.01278°N 81.55778°W / 48.01278; -81.55778
 • elevation330 m (1,080 ft)
Mouth Moose River
 • location
Gardiner Township, Cochrane District
 • coordinates
 50°43′42″N81°29′14″W / 50.72833°N 81.48722°W / 50.72833; -81.48722
 • elevation
48 m (157 ft)
Length443 km (275 mi)
Basin size37,000 km2 (14,000 sq mi)
Basin features
River system James Bay drainage basin

The Mattagami River is a river in Northern Ontario, Canada.

Contents

The Mattagami flows 443 kilometres (275 mi) from its source at Mattagami Lake in geographic Gouin Township [1] in the Unorganized North Part of Sudbury District, on the Canadian Shield southwest of Timmins, [2] to Portage Island in geographic Gardiner Township [3] in the Unorganized North Part of Cochrane District, in the Hudson Bay Lowlands. [4] 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. [5] The Mattagami River flows through the city of Timmins as well as the town of Smooth Rock Falls [5] and its drainage basin encompasses 37,000 square kilometres (14,000 sq mi). [2] It is close to tourism sites offering activities such as fishing, canoeing and nature-based relaxation.

The Mattagami's name comes from the Ojibwe and means either "the start of water" (maadaagami) or "turbulent water" (madaagami), but the local Ojibwe population claim "Mattagami" is a corrupted form of "confluence" (maadawaagami). According to the Mattagami First Nation, Mattagami means "Meeting of the Waters".

Course

The Mattagami River flows generally north for approximately 443 kilometres (275 miles). Its drainage area covers about 37,000 square kilometres. [6] The river originates at Mattagami Lake in the Sudbury District, southwest of the city of Timmins, and lies on the Canadian Shield. [7] The upper course incorporates Kenogamissi Lake, which is managed for downstream power generation. [8] The Mattagami flows north through the city of Timmins, which relies on the river as a source of drinking water. [9] Further north, it passes the town of Smooth Rock Falls. [10] Much of the middle section of the river has been developed for hydroelectric power, consisting of a chain of long lakes and reservoirs created by stations such as the Kipling, Smoky Falls, and Little Long Generating Stations. [11] The Mattagami continues its northward course, entering the flatter landscape of the Hudson Bay Lowlands. [12] Its course officially ends at the confluence with the Missinaibi River near Portage Island in the Cochrane District. [7] At this point, the two waterways combine to form the Moose River, which then flows northeast for approximately 100 kilometres (60 miles) before discharging into James Bay, an arm of Hudson Bay, near the communities of Moosonee and Moose Factory. [13] Significant tributaries feeding the Mattagami include the Groundhog River, the Kapuskasing River, and the Tatachikapika River. [14]

Mattagami River near Timmins, early 1900s YUL816825-MatagamiRiverTimmins.jpg
Mattagami River near Timmins, early 1900s

Economy

Where the Groundhog and Kapuskasing Rivers flow into the Mattagami, Ontario Power Generation operates the Little Long Generating Station, [15] with a dam just over 5 km in length.

Tributaries

Tributaries include the:

See also

References

  1. ↑ "Gouin" (PDF). Geology Ontario - Historic Claim Maps. Ontario Ministry of Northern Development, Mines and Forestry . Retrieved 2011-09-20.
  2. 1 2 "Rivers Flowing into Hudson Bay, James Bay or Ungava Bay - Moose River". Rivers. Atlas of Canada. Archived from the original on 2013-01-22. Retrieved 2011-09-20. Length to head of Lake Minissinakwa.
  3. ↑ "Gardiner" (PDF). Geology Ontario - Historic Claim Maps. Ontario Ministry of Northern Development, Mines and Forestry. Archived from the original (PDF) on 2012-03-27. Retrieved 2011-09-20.
  4. ↑ "Ecozones". Far North Ontario. Ontario Ministry of Natural Resources. 2011-04-07. Retrieved 2011-09-20.
  5. 1 2 Map 15 (PDF) (Map). 1 : 1,600,000. Official road map of Ontario. Ministry of Transportation of Ontario. 2010-01-01. Retrieved 2011-09-20.
  6. ↑ Boralex Canada Inc. (2025). Environmental and socioeconomic features: Mattagami River watershed. https://www.boralex.com/sites/default/files/2025-02/appf_environmental-and-socioeconomic-features_0.pdf
  7. 1 2 "Mattagami River Hydroelectric Generating Station Extensions Project (OPG-1) | ontario.ca". www.ontario.ca. 2014-03-20. Retrieved 2025-12-11.
  8. ↑ "Mattagami River Archives". OPG - Water. Retrieved 2025-12-11.
  9. ↑ "Drinking Water Source Protection Program". www.timmins.ca. Retrieved 2025-12-11.
  10. ↑ "Approval of the Mattagami River Hydroelectric Generating Station Extensions Project Environmental Assessment | ontario.ca". www.ontario.ca. 2016-09-26. Retrieved 2025-12-11.
  11. ↑ "Lower Mattagami Redevelopment Project". OPG Projects. Retrieved 2025-12-11.
  12. ↑ "Mattagami River Hydroelectric Generating Station Extensions Project (OPG-1) | ontario.ca". www.ontario.ca. 2014-03-20. Retrieved 2025-12-11.
  13. ↑ "Moose River". thecanadianencyclopedia.ca. Retrieved 2025-12-11.
  14. ↑ Mattagami Region Source Protection Committee. (n.d.). Assessment report for the Mattagami Region Source Protection Area. Drinking Water Source Protection. Retrieved December 11, 2025, from https://www.dwsp.ca/annual-reports/assessment-report/
  15. ↑ "Little Long Generating Station". Hydro - Northeast Plant Group. Ontario Power Generation.
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