Big Lake is located on the western edge of the city of St. Albert in central Alberta. The city of Edmonton is situated directly to the east. This freshwater lake is a large body of water that supports extensive stands of emergent vegetation. During low water years mudflats are also present along the north shore. The south shore supports large stands of mature aspen, birch and White Spruce.

Big Lake is recognized as an important waterfowl moulting and staging site, and in other studies it has been recognized as one of the 20 most important waterfowl habitat units in Alberta. Estimates of peak numbers of staging waterfowl in the 1970s and 1980s range as high as 26,000, with totals for the entire fall migration period likely being much higher once turnover rates are factored in. Although recent estimates are not available the general consensus is that waterfowl usage remains at about the same level. Although most of the waterfowl consist of dabbling and diving ducks, large numbers of Tundra Swans are also present during the last few weeks of October. Numbers general range in the low thousands (about 1% of the western North American Tundra Swan population), although in some years much larger numbers are recorded (e.g., an estimate of 12,000 in October, 1998).

In addition to its importance for staging waterfowl, Big Lake also supports a large colony of nesting Franklin's Gulls in the west bay of the lake. In the 1980s, this colony was estimated to contain between 500 and 3000 nests (the latter number, when doubled, is greater than 1% of the world's estimated population). Recent estimates of this colony's size have not been obtained due to its inaccessible nature. Nesting colonies of Eared Grebes and Black Terns are also present.

In years when water levels are low, a variety of migrating shorebirds can also be observed at the north end of the lake. Common species include yellowlegs, dowitchers, Pectoral Sandpipers, American Avocets, and a variety of small sandpipers.

Big Lake Conservation Natural Area was designated as a provincial Special Places site in 1999. This natural area, however, covers only 1,106 of the site's 2,140 hectares. The lake has also been recognized by Ducks Unlimited as a "Wetlands for Tomorrow" site. In addition to its importance for wildlife, the lake also functions as a natural reservoir and flood control entity for the city of St. Albert. In the 1980s, water level fluctuations resulted in some drainage efforts to promote commercial beach uses. Industrial and resource development, as well as expanded agricultural use of the area could have large negative impacts on the productivity of the lake.