Lake Koshkonong

Lake Koshkonong
Lake Koshkonong Show map of Wisconsin Lake Koshkonong Show map of the United States
Location	Jefferson / Rock / Dane counties, Wisconsin, U.S.
Coordinates	42°52′27″N 88°57′29″W / 42.87417°N 88.95806°W / 42.87417; -88.95806
Lake type	Reservoir
Primary inflows	Rock River
Primary outflows	Rock River
Basin countries	United States
Surface area	10,460 acres (42 km2)
Average depth	6 ft (2 m)
Max. depth	7 ft (2 m)
Surface elevation	774 ft (236 m)

Lake Koshkonong is a reservoir in southern Wisconsin, which was transformed from its original marshland by the construction of the Indianford Dam in 1932.^[1] The lake lies along the Rock River, with the river acting as both the primary inflow and the primary outflow for the lake. Lake Koshkonong begins 5.5 mi (8.9 km) downriver from Fort Atkinson, with the large majority of the lake located in southwestern Jefferson County. Small portions of the lake extend into southeastern Dane and northern Rock counties.

After the creation of the Indianford Dam, which was built several miles down the Rock River from Lake Koshkonong, the lake gained a surface area measuring 10,460 acres (42.3 km²). It remains very shallow with an average depth of six feet (1.8 meters) and a maximum depth of seven feet (2.1 meters). The dam itself measures 13 feet (4.0 meters) high and with a length of 500 ft (150 m) at its crest. Maximum capacity of the reservoir is 107,000 acre⋅ft (132,000,000 m³).^[2] Both dam and reservoir are owned and operated by Rock County.^[3]