Wawaitin Generating Station is located on the Mattagami River System at the outlet of Kenogamissi Lake, approximately 30 km upstream from the City of Timmins.
This station was built in 1912 and acquired by Ontario Hydro/OPG in 1944. The powerhouse has four units with a maximum generating capacity of 11 MW. The dam consists of east and west concrete structures. The east dam is equipped with seven sluices while the west dam is equipped with five.
Smoky Falls Generating Station is located on the Mattagami River system near Kapuskasing. The station originally had two generating units which began operating in 1931. A third unit was added in 2015 increasing the station’s maximum capacity to 267 MW.
Sandy Falls Generating Station is located on the Mattagami River system near the City of Timmins and began operating in 1911. This run-of-river facility is fed from Wawaitin GS and the Peterlong Lake Dam on the Grassy River. The station has one generating unit with a maximum capacity of 6 MW. The dam is a concrete weir which extends across the river.
The Peterlong Lake Control Dam is located on the Mattagami River system near the City of Timmins and began operating in 1916. The dam is situated at the outlet of Peterlong Lake and upgraded to a concrete structure in 1972. The dam has three log sluices and controls Peterlong Lake flow into the Grassy River, which flows into the Mattagami River upstream of Timmins. It also serves to mitigate flooding in Timmins, as it is the second largest reservoir on the Upper Mattagami River system.
The Mesomikenda Control Dam is located on the Mattagami River System at the outflow of Mesomikenda Lake. This dam was originally constructed in 1917 and was rebuilt in 1937 after it was damaged by a fire. Ontario Hydro/OPG acquired the site in 1944. This concrete dam is composed of three sluices and one spillover weir.
The Mattagami Lake Control Dam is located at the outlet of Mattagami Lake and was originally constructed in 1921. Ontario Hydro acquired the site in 1944. This concrete dam has six sluices and controls Mattagami Lake flow into Kenogamissi Lake, which is the forebay for Wawaitin GS. This provides flood control for Timmins as it has the largest storage capacity on the upper Mattagami River system.
Lower Sturgeon Generating Station is located 48 km northeast of Timmins and began operating in 1923. This run-of-river facility has two units and a maximum generating capacity output of 14 MW. The concrete dam has 16 sluices and a log slide.
Little Long Generating Station is located on the Mattagami River system near the Town of Kapuskasing. The station originally had two generating units which began operating in 1963. A third unit was added in 2015 increasing the station’s maximum generating capacity to 208 MW.
Kipling Generating Station is located on the Mattagami River downstream of Harmon GS. Constructed in 1966, it is the last power plant built in the series of cascading power facilities on the lower Mattagami River. It is operated as a peaking facility and has three generating units with a maximum generating capacity of 230 MW. The concrete dam is terminated by earth dams which extend to the natural soil banks at each side of the river.
The Horwood Lake Control Dam is located at the outlet of Horwood Lake. It was constructed in 1956 and acquired by Ontario Hydro/OPG in 1990. This dam controls Horwood Lake flow into the Groundhog Lake and the Groundhog River. The dam is constructed of concrete with earth fill dykes and has seven stoplog sluices.