The Effect of Water Diversions and Drought in the Drying-up of Beaverhills Lake, a 140 km2Ramsar Wetland in Central Alberta

Abstract

Beaverhills Lake, a shallow wetland of roughly 10 km × 18 km, shrank in size until it completely dried up in 2006. The primary cause was a ten-year cycle of drought beginning in 1995 when annual precipitation fell below the 30-year mean of 450 mm. Superimposed on the drought, inflowing creeks were dammed for the purpose of restoring or creating upstream duck breeding habitat and to flood hay meadows for local farmers. Since 1973, 17 impoundments and weirs have diverted 1.5 million cubic meters of water per annum. The proportional cost to the lake grew as it became smaller and shallower, and the evaporation rate increased. In 1987, under the North American Waterfowl Conservation Plan, Beaverhills Lake was designated as a Wetland for Tomorrow and an International Ramsar site. In 1996, the lake became a Western Hemisphere Regional Shorebird Reserve. None of these accolades, intended to safeguard the wetland from mismanagement, appears to have helped in halting or reversing the lake's decline. Long-range precipitation and temperature records available from Environment Canada do not support the hypothesis that climate change was a factor in the drying-up of Beaverhills Lake.