Dauphin Lake is located in western Manitoba near the city of Dauphin, Manitoba. The lake covers an area of and has a drainage basin of about . The Mossy River drains the lake into Lake Winnipegosis. The basin is drained by seven major streams and has a total relief of . The lake is located within the territory of three rural municipalities; in descending order of area they are the Rural Municipality of Ochre River, the Rural Municipality of Dauphin, and the Rural Municipality of Mossey River.