| Lake Koshkonong | |
|---|---|
  Lake Koshkonong  Lake Koshkonong | |
| Location | Jefferson / Rock / Dane counties, Wisconsin, U.S. |
| Coordinates | 42°52′27″N 88°57′29″W / 42.87417°N 88.95806°W |
| 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]
- ^ "When Lake Koshkonong was a Marsh". Wisconsin 101: University of Wisconsin -- Madison. February 13, 2024. Archived from the original on January 25, 2024. Retrieved May 8, 2023.
- ^ Environmental Assessment [1] Wisconsin DNR, March 18, 2005
- ^ Indianford Dam model scenarios [2], Rock Koshkonong Lake District Mongomery board presentation, June 13, 2019