Lake Wisconsin

Lake Wisconsin
Aerial view of the Prairie du Sac Dam, which impounds Lake Wisconsin, taken during the June 2008 flood.
Location	Columbia / Sauk counties, Wisconsin, United States
Coordinates	43°18′36″N 89°43′29″W / 43.31000°N 89.72472°W / 43.31000; -89.72472Coordinates: 43°18′36″N 89°43′29″W / 43.31000°N 89.72472°W / 43.31000; -89.72472
Lake type	reservoir
Primary inflows	Wisconsin River
Primary outflows	Wisconsin River
Basin countries	United States
Surface area	9,500 acres (3,800 ha)
Max. depth	40 ft (12 m)
Surface elevation	about 774 ft (236 m)

Lake Wisconsin is a reservoir on the Wisconsin River in southern Wisconsin in the United States. It is located in Columbia and Sauk counties, approximately 5 mi (8 km) southeast of Baraboo and 25 mi (40 km) NNW of Madison. Today it is home to the Wisconsin wine appellation of the Lake Wisconsin AVA.

It was formed by the construction of a dam at Prairie du Sac, which was begun in 1911 and completed in 1914. It is part of the Wisconsin River system of reservoirs. The lake has a maximum depth of 40 ft (12 m). It has a shoreline of 57 mi (90 km) and an area of 9500 acres (38 km²).

Its construction effectively ended the Fox-Wisconsin Waterway connection to the Mississippi River, although commercial traffic had ended decades before completion of the dam.

The lake provides flood control and is a popular destination for recreational boating and fishing.

The Merrimac Ferry crosses the lake at Merrimac, Wisconsin.