Frank Lake is located approximately six km east of the town of High River and about 50 km south of Calgary, Alberta. It is a shallow lake bordered by marshes and low-lying meadows, although some of the shoreline is non-vegetated. Much of the surrounding landscape has been cultivated, although some native grassland remains. Water levels within the lake are controlled primarily by treated wastewater from a meat packing plant, by tertiary effluent from High River, and by a portion of Highwood River. The main lake basin is now 1,010 ha while 808 ha of adjacent land are back-flood.
Frank Lake has a history of fluctuating water levels; during the 1930s, 1940s, and mid 1980s it was dry for extended periods of time, while during the 1950s and mid 1970s flooding occurred. On occasions when the lake flooded, the local and provincial governments called for drainage of the lake. Ducks Unlimited (DU) persuaded the government away from this course of action and since then have been managing the area and controlling water flow. After the lake dried up in the 1980s, DU looked for a source of water for the lake.
Frank Lake supports significant numbers of waterfowl and shorebirds during both spring and fall migration. Up to 70 Trumpeter Swans of the Rocky Mountain population stage at Frank Lake in the spring and fall (2.8 % of this population). As well, thousands of Tundra Swans stage here too; in the fall as much as 1.5 % of the North American population of the species are found here. Thousands of staging ducks are found at Frank Lake during migration; in March, 1995, 10,000 Northern Pintails were observed, which is a nationally significant number. Good numbers of shorebirds are seen here during fall migration, such as 600 Bairds Sandpipers and 900 Long-billed Dowitchers, along with 150 Marbled Godwits (1.5% of the national population).
Several threatened species occur here, but some such as Burrowing Owl (endangered), Loggerhead Shrike (threatened) and Piping Plover (endangered - last recorded in 1990) have not been seen in recent years. Others, such as Peregrine Falcon (vulnerable), Ferruginous Hawk (vulnerable), Long-billed Curlew (vulnerable), and Short-eared Owl (vulnerable) are all still seen at Frank Lake. The uncommon Bairds Sparrow also breeds here.
Frank Lake is considered the most important wetland in southwestern Alberta for breeding water birds. The most abundant breeding water bird is perhaps Franklins Gull, because several thousand of this species nest here (in 1971 the colony consisted of over 10,000 individuals). Other common breeders are: Eared Grebe, Black-crowned Night-Heron, California Gull, Ring-billed Gull, and Common Tern. Many other species breed in smaller numbers, including the unexpected Black-necked Stilt. In the fall, the shorebird migration is noteworthy over 20 species have been seen including species that are seen more commonly further west.
BirdLife International (2020) Important Bird Areas factsheet: Frank Lake (south). Downloaded from http://www.birdlife.org on 01/10/2020.