The Spray Lakes Reservoir, located 16 km south of Canmore, is in the subalpine ecoregion of Kananaskis Country. Developed in 1951 after the construction of Three Sisters and Canyon Dams, the Reservoir provides water for three power generating stations. The lake reaches its peak elevation (full supply) in late July to early August. Drawdown is approximately 12.5 metres with its lowest level occurring during the winter months. The lake is widely used by fishing, boating and camping enthusiasts.
The Three Sisters Dam at the lake's north end was not originally designed for the probable maximum flood (pmf) risk. This risk combined with known seepage beneath the dam led to a decision in 1987 to permanently lower the full supply level (fsl) of the lake from 1701.7 metres above sea level (masl) to 1697.6 masl so the pmf could be maintained. The dam was also upgraded to control seepage. As a result of the lower lake level, 208 hectares (ha) of shoreline was exposed offering little to no wildlife benefit and limited recreation potential.
In 1991, TransAlta Utilities developed a reclamation plan for 128 ha of shoreline and an earthen spillway adjacent to Canyon Dam. Input from Alberta Forest Service, Trout Unlimited, Kananaskis Country as well as public and interest groups was incorporated into the plan. The objectives of the project were to sustain the integrity of the lake by enhancing the aesthetic value for recreational users, as well as to provide forage and habitat to wildlife by establishing a palatable, self-sustaining vegetative cover. Work would take place from 1992 to 1995.