[2] Reid Lake was formed with the construction of the Duncairn Dam[3] in a glacial meltwater channel along the course of Swift Current Creek in 1942.

[7][8] Duncairn Dam (50°04′27″N 108°02′46″W / 50.0743°N 108.0462°W / 50.0743; -108.0462) was constructed in 1942 by the Prairie Farm Rehabilitation Administration (PFRA) to supply water for the Rush Lake, Waldeck, and Herbert irrigation projects.

The spillway was redesigned and rebuilt "provide a mass concrete chute section and hydraulic jump stilling basin to contain the extreme runoff flows anticipated."

[10] The Duncairn Reservoir Migratory Bird Sanctuary (MBS)[11] encompasses the entirety of Reid Lake and is in the semi-arid region known as Palliser's Triangle.

Reid Lake lacks islands, which restricts the number of colonial-nesting water birds, and its steep sides limit the amount of riparian habitat.

Other species found at the lake include the barn swallow, common nighthawk, western grebe, and northern leopard frog.

Fish species commonly found in Reid Lake include walleye, yellow perch, and northern pike.