Pinawa Generating Station

First all-season hydroelctric plant in Manitoba

Pinawa Generating Station was the first all-season hydroelectric plant built in Manitoba and the first on the Winnipeg River system. It was also the first in the world to be developed in such a cold climate. Procurement, construction, and commissioning had a lot of local involvement. A railway and a town were built for the construction. Design engineering was provided by engineer Fred Stark Pearson from New York.

Location

The location of the dam is technically not on the Winnipeg River but on a much smaller branch called the Lee River. Under normal water conditions, the Lee River is a small tributary to the Winnipeg River; however, due to the topology of the area, water flows over a ridge and into the headwaters of the Lee River when the Winnipeg River is experiencing floods. This natural arrangement made it ideal for building a generating station in the dry while avoiding the powerful Winnipeg River flows. Pinawa is derived from the Cree word pinnowok, meaning “quiet water”, referring to the quiet and sheltered nature of water flow here.

Winnipeg Electric Railway Company

The construction of Pinawa demonstrated the willingness by its owner, the Winnipeg Electric Railway Company, to embrace new technology at a remote site with relatively basic equipment. The project was undertaken with no conclusive evidence that the river was an appropriate site for hydroelectric development or that the plant would be a reliable source of power during the winter months. Critics insisted that the estimated production of 18.6 megawatts was far beyond the needs of Winnipeg. Others questioned if electricity could be transmitted over such a great distance. All of this became moot when, ten years following the station’s completion, Winnipeg’s population had quadrupled and the demand for power soared.

Logistics

Transportation to the site was a major challenge. There were no roads or railways to the construction site and no bridges to cross the Winnipeg River. When existing ‘lumberjack trails’ became impassable, spruce logs were laid across them to create corduroy roads. In total, 26 kilometres of corduroy roads were built for the project. The river itself also provided a route for the transport of heavy equipment through Lac du Bonnet, by means of a scow in summer and by sled in winter. Between 50 and 75 teams of horses were used to haul material around the construction sites. Scores of handlers and, blacksmiths, and food for the horses were also a major logistical consideration. Although steam-driven derricks, shovels, and drills were used whenever possible, most of the labour was manual. Rock drillers were paid 15 cents an hour for their demanding work.

Channel Improvements

To allow more water to flow through the Lee River, the headwater channel was widened and deepened. Much of the area was composed of granite outcrops of the Canadian Shield that required a significant amount of drilling and blasting. The excavated material was piled alongside the new channel and is still recognizable today. Three weirs were placed within the main waterway of the Winnipeg River to divert water into the new channel, with a control structure at the channel entrance to regulate water flow to the Pinawa station. The structure was of such importance that employees lived on-site year-round and had a telephone connection to the station. Today, the upstream portion of the river is called the Pinawa Channel and the downstream portion is the Lee River.

Construction Schedule

Construction of the Pinawa Generating Station began in 1902 and was completed on 9 June 1906 at a cost of $3-million, or as much as $2-billion in today’s dollars. During its initial year of operation, six generating units produced 8 megawatts of electricity. Three more units were added the following year, bringing the total output to 14 megawatts.

Power Enhancements

In the years after its completion, demand for power grew to such an extent that additional capacity was needed. In 1912, modifications increased the elevation of the forebay by placing sluiceways and stoplogs along the top of the spillway weir and increased the height of the surrounding dikes. The result was an increase in water elevation (head) to 14 metres and an increase in station capacity to 22 megawatts.

Decommissioning

Through the 1940s and ʼ50s, the demand for electricity grew steadily, resulting in the expansion of the Seven Sisters Generating Station located downstream of the Pinawa Channel entrance. Three units were added to Seven Sisters between 1948 and 1952, which brought its capacity to 150 megawatts. To maximize the generating potential of the Winnipeg River system, it was decided to return the water diverted to the Pinawa plant back to the river. So, before the final unit at Seven Sisters was commissioned, the small and inefficient Pinawa Generating Station was shut down in October 1951, after 45 years of successful operation. Any one of the six generators at Seven Sisters produced greater power than Pinawa’s entire output.

The station’s equipment was removed, and its buildings were dismantled. The main earthen works and concrete superstructure were abandoned.

Provincial Heritage Park

Today, the old plant and its surrounding area have been turned into the Pinawa Dam Provincial Heritage Park with pathways and placards highlighting the history of the site. Commemorative plaques recognizing the importance of the Pinawa Generating Station as a milestone in Canadian engineering were dedicated in 1987 (APEM) and 2008 (IEEE).