Frozen Dam

It was the Seven Sisters Dam which I visited few months earlier. At first look I thought the dam had been shut down due to ice. After few moments I realized it was running in full swing and water was running beneath the ice surface. Seven Sisters Generating Station is Manitoba Hydro's largest producer of electricity on the Winnipeg River in southeastern Manitoba. Located about 90 kilometres (km) east of the City of Winnipeg, The generating station operates at a maximum capacity of 150 megawatts (MW) and can produce. Seven Sisters is a "run-of-river" design, which means that water flowing into the generating station from upstream is used immediately, not stored in the forebay for later use. The spillway at Seven Sisters is flanked to the north and south by non-overflow, concrete wingwalls. In winter, to prevent an ice buildup on the concrete of the spillway and wingwalls, which would create a pressure hazard, an air bubbler system has been installed to stop ice from forming. For the same reason, the spillway gates have been fitted with heaters
http://www.ieee.ca/millennium/seven_sisters/seven_history.html