The Alberta government and TransAlta – an electricity power generator and wholesale marketing company headquartered in Calgary – reached an agreement June 4 to use the Ghost Reservoir to help control flooding in the area.
The plan is to hold the Ghost Reservoir, located west of Cochrane, at an elevation of 3,902 feet – about eight feet lower that normal range – until July 31, approximately six weeks longer than the current operating pattern. This provides greater capacity to hold water during flood conditions, according to both parties.
“The agreement with TransAlta on modified operations at Ghost Reservoir provides another important layer of flood protection,” said Minister of Environment and Sustainable Resource Development Robin Campbell.
“The Government of Alberta and TransAlta have been working hard to reach this agreement for the benefit of the residents along the Bow River.”
The precautions are being taken in response to historic flood levels of both the Bow and Elbow River that caused widespread devastation in Bragg Creek, Calgary, Canmore, High River and Morley in June 2013.
At full supply level, Ghost Reservoir can hold about 3,910 ft of water. The lower level of the reservoir will see the flow of water reduced.
According to Campbell, it is estimated the modified operations at Ghost Reservoir would reduce peak flows along the Bow River by an additional 100 cubic metres per second. This is on top of the peak flow reduction of around 400 cubic metres per second that was provided by the upstream TransAlta reservoirs during the 2013 floods.
“In 2013, our teams responded quickly and responsibly to hold back a significant amount of water,” said president and chief executive officer of TransAlta Dawn Farrell.
“Since then, we’ve been working with communities to strengthen our communications and better prepare. Today’s agreement is just one more step in that process.”
The location of the Ghost Reservoir makes it an effective tool for flood mitigation, according to Farrell. Located upstream of Calgary, but not too close to the headwaters, Ghost Reservoir would have more warning time in advance of a flood event compared to most TransAlta facilities.
The agreement with TransAlta on Ghost Reservoir falls in line with the $104 million program for priority upgrades to water management infrastructure in Southern Alberta. The Ghost Reservoir agreement is for this year only, but an evaluation by both parties after July 31 may lead to a longer-term arrangement.
