Photo by Linda HeronPhoto Credit

Smoky Falls Generating Station, Mattagami River

The Lower Mattagami Project is a hydroelectric project that includes the construction of a three-unit facility at Smoky Falls Generating Station site.

Existing Facility

Smoky Falls has been in-service since 1926. Minor concrete repair was made to the existing concrete dam during the construction of the new generating facility. The generating units at the existing facility will be decommissioned once construction of the adjacent new facility is complete. All civil structures, including the spillway and earth-filed dykes shall be retained. The powerhouse and gravity dam will remain as a water retaining structure.


The new construction includes three vertical propeller turbine-generator set, penstocks and draft tubes, and three new three-phase transformers. These new generating units have an installed capacity of approximately 267.9 MW at a head of 34.8 metres.

A new remotely controlled sluicegate is installed to replace the existing #3 sluicegate.

Water from the Mattagami River is conveyed from the intake structure to the powerhouse via penstocks, where each penstock supplies one generating unit.

Water from the Smoky Falls GS is returned to the Mattagami River via a 400 metres long tailrace canal that converges with the diversion spillway and the tailrace for the old original Smoky Falls generating station.

The new Smoky Falls GS dam, spanning 200 metres in length, is made of concrete. The concrete structure includes headworks and the powerhouse section in the river channel, from which gravity sections extend to the earth dam on the west bank, then on to the old original Smoky Falls generating station gravity dam, and then to a 381 metres long spillway structure on the east bank.

Located 85 km north of Kapuskasing, Ontario, and just east of the old original Smoky Falls generating station, the facility is operated remotely from OPG’s Northeast Control Centre located at the Porcupine Transformer Station in Timmins, Ontario. The new generating units will be connected to Hydro One’s 230kV L20D and H22D circuit.

Location: Harmon Township, Ontario
River System: Mattagami River
Nameplate Capacity: 267.9 MW
OPA Contracted Capacity: 267.9 MW
Operator: Ontario Power Generation
Technology: Hydroelectric
Turbines: Three vertical propeller turbines
Originally Built: 1926
Coordinate: 50° 00’ 17” N, 82° 09’ 55” W

Project Progress (December 31, 2013)

  • Concrete pouring continued in service bay, intake and powerhouse areas
  • Unit 1 stator winding and rotor assembly completed
  • Unit 2 stator core loop test completed and the stator frame placed in generator pit
  • Steel superstructure erection over unit 3 completed and powerhouse fully enclosed with pre-cast panels
  • Erection of retaining walls to protect east and west tailrace walls from erosion continued

Ontario Power Generation Inc.