The Mann Lakes are two close basin lakes in Alberta. Once a single lake named Mann Lake, the construction of Highway 28 in 1961 split the lake in two. The more southerly Upper Mann Lake lies at 54°08′37″N 111°30′57″W, and just north of it, the more northerly Lower Mann Lake at 54°10′N 111°30′W. Since 1980, their water level has been steadily declining.