Ontario Power Generation

SILVER FALLS STATION

PLANT GROUP: Northwest Plant Group
DRAINAGE BASIN: Lake Superior
RIVER: Kaministiquia
TRIBUTARY: Dog River

NEAREST POPULATION CENTRE: Thunder Bay (48 KM (30 Miles) Southeast)

IN SERVICE DATE: September 1, 1959

BUILT BY: Hydro-Electric Power Commission of Ontario
Asset Transferred to Ontario Power Generation: April 1, 1999

NUMBER OF UNITS: 1
CONTROL: Remote from Thunder Bay

HISTORICAL NOTE:

In 1907, the Commission, in anticipation of industrial growth around Port Arthur, conducted investigations of potential power sites in this area. Three tentative schemes by which the demands for power in the district could be most reasonably met were considered. The first and most significant of these schemes, known then as the Dog Lake development, was to develop the effective head on the Kaministikwia River between Dog and Little Dog Lakes. The distinguishing feature of this development would be the construction of about 1067 m (3,500 ft) of headwater tunnel. It was estimated that this station, if built, would provide 13 675 hp and would require a short transmission line to connect it directly with the city of Port Arthur.

In 1908, a private engineering firm, Smith, Kerry and Chase, submitted a report to the city of Port Arthur in connection with the development of power at Dog Lake. The scheme of the development included the construction of 1646 m (5,400 ft) of tunnel through the height of land between Dog Lake and Little Dog lake. Extensive exploration work along the proposed tunnel line by means of pits and borings, showed fine gravel and sand, but not evidence whatever of rock.

Around the year 1913, it was thought that the topography of the site lent itself to the development of power by means of a scheme using a flume. Consequently, the site was surveyed with a view to comparing its practical and economic advantages with the tunnel schemes. A report on comparative estimates of the two schemes was submitted to the municipality of Port Arthur but neither plan proved feasible.

Previous to 1945, all requests for more power in the district could be economically met by the development of other power sites in the area. However, in 1945, when the Lakehead cities were faced with possible power shortages, it was decided to further investigate the Silver Falls site. Drill rigs were set up and borings made along an assumed tunnel line, but again no rock was encountered. As the request for more power became urgent, the Silver Falls site was shelved temporarily. Activities were then transferred to the Aguasabon site where conditions appeared more favourable and the site was close to industry wanting more power.

Demands for more power continued and in 1956 Hydro resumed investigations of the Silver Falls site. By using the seismic method, a ridge of competent rock through which the hydraulic tunnel could be driven was located and a tunnel line established. This line eventually proved to be satisfactory. Thus the most practical and economic solution to the major problem affecting the development was reached.

Early in 1957, the Provincial Government approved Hydro's request to develop the site. This request included: construction of an intake, a hydraulic tunnel, a single-unit powerhouse and necessary transmission facilities for the 60 000 hp Silver Falls generating station.