Big Lake, a relatively little known jewel of the capital region, is located at the northwest corner of Edmonton and the southwest corner of St. Albert. Parkland County borders the lake on the south and Sturgeon County on the north. The lake sits on the sands and gravels of the Empress Formation, an aquifer 30 meters below its surface that was laid down by retreating glacial meltwaters.
Centred at 53°36'N, 113°43'W, Big Lake is part of the 260 km long Sturgeon River that begins at Hoople Lake and flows east to the North Saskatchewan River. Atim Creek flows into Big Lake from the west and Carrot Creek from the north.
Big Lake is about 8 km in length and 3 km at its widest point. At the delta, one of only three birdsfoot deltas to be found in Alberta, the lake narrows to 100m. The lake is shallow, with depths varying between 0.3 to 4.1 m. Banks along the southern shore are steep, directing the lake’s flood waters towards the west, north and east to feed surrounding marshlands during high water years.
Old stands of white spruce grow on the northeast shore of the lake and a deciduous forest on the south contain highly diverse vegetation with unusual and rare plant species that include orchids and ferns.
More than 235 bird species have been recorded at Big Lake, some 180 are recorded annually. At risk species that use the lake include Trumpeter Swans, Sprague's Pipits and Peregrine Falcons.
The western bay of the lake provides rare nesting habitat for Franklin's Gulls, a species that builds floating nests anchored to vegetation growing in shallow water. Known to have one of the longest migration routes, Franklin's gulls fly south as far as southern Peru and northern Chile every year. In 1983, Alberta Fish and Wildlife researchers noted two Franklin's gulls colonies in the west bay of Big Lake that together comprised between 2,000 and 3,000 individuals.
In the Fall, the lake is a staging area for Tundra Swans and Pelicans. Fall populations of swans have been as high as 20,000. Cormorants, Loons, Great Blue Herons and Ospreys fish the lake. Lesser Yellowlegs, Dowitchers, American Avocets and Sandpipers reside during low water years. In 2005 a family of Great Egrets nested at Big Lake for the first time and raised four youngsters.
Fish species found in the lake include Northern Pike, Goldeye, White Sucker, Walleye and Sticklebacks.
The lands surrounding Big Lake provide important habitat for Moose, White-Tailed Deer, Beaver, Muskrat, Mink, Skunk, Coyote, Red Fox, Porcupine, Snowshoe Hare and Red Squirrel.