May begins Calgary’s flood season, so let’s talk about river dams. Dams control water flow and can also supply drinking water, irrigation and electricity.

Peace Bridge, June 2013. ID 31769546 © Wayne Stadler |

The first hydroelectric station in Calgary was built in 1893 – a weir at Prince’s Island. Ten years later, demand was outstripping supply.

Horseshoe Falls dam and power plant, Alberta., 1913, (CU1175105) by Unknown. Courtesy of Glenbow Library and Archives Collection, Libraries and Cultural Resources Digital Collections, University of Calgary.

Calgary Power Company (today’s TransAlta) began construction to meet demand from a tenfold increase in population (from 4,398 Calgarians in 1901 to 43,706 in 1911). Horseshoe Dam, Alberta’s first large-scale hydro dam, began operations in 1911. It’s one of seven plants on the Bow River today, making it the province’s most managed river.

Hydro dams work best with consistent water flow. Lake Minnewanka Dam was constructed in 1912 to partially regulate the Bow’s seasonal flows. With ample power, more investment poured into Calgary, including the Canadian Pacific Railway’s engine repair shop in Ogden.

Construction of Ghost River dam across Bow River, west of Cochrane, Alberta. [ca. 1928-1930], (CU1213751) by Unknown. Courtesy of Glenbow Library and Archives Collection, Libraries and Cultural Resources Digital Collections, University of Calgary.

Plans for additional dams were met with opposition to further development in Rocky Mountain (later Banff) National Park. In 1929, Ghost River Dam and Reservoir was constructed on land leased from Stoney Nakoda First Nations.

Despite regulation, flooding remained a risk. Bearspaw Dam was constructed in 1954 to prevent winter flooding and ice packing. The dam is named after Chief Jacob Bearspaw, who signed Treaty 7 at Blackfoot Crossing. It is one of the city’s two drinking water reservoirs.

The Rockyview General Hospital with kayaks and canoes anchored at the Calgary Canoe Club on Glenmore Reservoir, 2021. ID 231175313 © Ramon Cliff |

The other reservoir is Glenmore (Gaelic for “big valley”). The area was settled by Sam Livingston, who was born in County Wicklow, Ireland and brought the first mechanised farm equipment to Calgary. The reservoir was completed in 1932, with Sam’s house moved to Heritage Park.

In 2005, the highest waters in two centuries overflowed Glenmore Dam, with 2,000 residents evacuated. In June 2013, heavy rainfall and snowmelt caused both the Bow and Elbow Rivers to flood. 100,000 people were under evacuation orders, with the flood causing $6 billion in damage. It was the worst flooding in Alberta’s history and the provincial government is currently evaluating the construction of another dam.

From over a century of development, the Bow River’s dams are “one of the great industrial projects of Canada’s history”.1

– Anthony Imbrogno is a volunteer with The Calgary Heritage Initiative Society/Heritage Inspires YYC

– All copyright images cannot be shared without prior permission

1 “Protecting the health of Alberta’s Bow River”, The Globe and Mail, 11 October 2015,