Ghost Lake is a man-made reservoir located approximately 45 km west of Calgary, Alberta that is fed by the Bow River. Since 2014 the water levels in the reservoir have been lowered during the spring to prevent downstream flooding in Calgary. The extreme water level fluctuations have wreaked havoc on the lake ecosystem. The lake is approximately 5 km wide (north-south) by 30 km long (east-west). The lake is deepest on the east end near the dam with depths close to 200 m. The lake becomes progressively shallower towards the west end where the Bow River enters the reservoir. The west end of the lake is a very unique ecosystem due to its shallow depth and marshy environment. During the late spring and early summer this area of the lake has become an important stopover and breeding ground for migrating waterfowl. Some of the common species include Canadian Geese, snow geese, ducks of several varieties, loons, and herons. This shallow area of the lake is also an important habitat for fish and for amphibians including frogs and toads.
In 2005 and 2013, Calgary experienced extreme flood events. The worst flood event was in June 2013. The flood was caused by above an average snowpack and a late snow melt in the mountains, and above average rainfall, which may be due in part to global climate changes. The Bow River and Elbow River converge near the city downtown core, and flow through Calgary. Much of the Calgary downtown core was submerged under 1 m of water and the damage was in the hundreds of millions of dollars. Since 2013, the Alberta Government has ordered TransAlta Corporation, the owner and operator of the dam to preemptively lower the Ghost Lake water level from early May to July 7th to allow the reservoir to act as a buffer for extreme runoff events, and to protect the city of Calgary (Kaufmann, 2016). The lake level is lowered by as much as 6 m (Kaufmann, 2016).
Lowering the lake level has had many negative ecological and socio-economic side effects. The west end of the lake, including the important marsh areas dry up and disappear (Appendix A). This author has observed that since 2013 there has been a significant decrease in the number of migratory waterfowl stopping to use this habitat. Amphibians and fish populations are also effected. The amphibians have lost their habitat, and the fish are routinely trapped in small pools. Riverbank erosion is also occurring along the west end of the lake when the water level is lowered in the spring. This is due to the increased flow velocity though a narrower channel.
On the east end of the lake there is a marina, and cottage development. When the water level is lowered by six metres, the docks and boat launches cannot be used (Kaufmann 2016, Appendix A). The economic impact to the marina has been substantial, significantly reducing their profitable season (Schmidt 2015). The nearby cottage owners are also affected, and cannot use the lake until after July 7th when the lake levels begin to return to normal. Some shallow water wells have also gone dry due to the lower water levels. The socio-economic consequences have been loss of income, loss of recreational use of the lake, and lowered property values.
The cause of the 2005 and 2013 flood events were higher than usual snowpacks in the mountains, a later snowmelt, and higher than average spring rainfall events. Some of these factors may be due in part to global climate change. The Government’s decision to lower the lake level by six metres, for two months is of great concern to many people. It is believed by many that the decision was made solely to protect the city of Calgary and does not consider the negative ecological, biological, and socio-economic impacts to Ghost Lake, businesses, and the residents. Development on flood plains, and near river basins has significant unexpected negative ecological and socio-economic consequences on a local, regional, and global scale, especially with climate change.
Ghost Lake, Alberta