| Official Name: | Lake Koshkonong, Wisconsin |
| Settlement Type: | Census-designated place |
| Mapsize: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Wisconsin |
| Subdivision Type2: | County |
| Subdivision Name2: | Jefferson |
| Subdivision Type3: | Town |
| Subdivision Name3: | Koshkonong, Sumner |
| Unit Pref: | Imperial |
| Area Total Km2: | 77.4 |
| Area Land Km2: | 37.1 |
| Area Water Km2: | 40.3 |
| Area Total Sq Mi: | 29.9 |
| Area Land Sq Mi: | 14.3 |
| Area Water Sq Mi: | 15.6 |
| Population As Of: | 2020 |
| Population Total: | 1239 |
| Population Density Km2: | auto |
| Population Density Sq Mi: | auto |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation Ft: | 781 |
| Coordinates: | 42.8606°N -88.9403°W |
| Blank Name: | FIPS code |
| Blank Info: | 55-41583[1] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 1852244 |
Lake Koshkonong is a census-designated place (CDP) in the towns of Koshkonong and Sumner, Jefferson County, Wisconsin, United States. The population was 1,239 at the 2020 census.[2] Lake Koshkonong is in the area.
Lake Koshkonong is located at 42.8606°N -88.9403°W (42.860475, -88.940344).[3]
According to the United States Census Bureau, the CDP has a total area of 29.9 square miles (77.4 km2), of which 14.3 square miles (37.1 km2) is land and 15.6 square miles (40.3 km2) (52.11%) is water.
As of the census of 2000, there were 1,219 people, 492 households, and 338 families residing in the CDP. The population density was 85.2 people per square mile (32.9/km2). There were 809 housing units at an average density of 56.6/sq mi (21.8/km2). The racial makeup of the CDP was 98.36% White, 0.25% Native American, 0.16% Asian, 0.16% from other races, and 1.07% from two or more races. Hispanic or Latino of any race were 1.39% of the population.
There were 492 households, out of which 25.4% had children under the age of 18 living with them, 59.8% were married couples living together, 4.7% had a female householder with no husband present, and 31.1% were non-families. 22.6% of all households were made up of individuals, and 9.8% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 2.88.
In the CDP, the population was spread out, with 21.2% under the age of 18, 6.2% from 18 to 24, 26.4% from 25 to 44, 32.1% from 45 to 64, and 14.0% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 108.0 males. For every 100 females age 18 and over, there were 106.9 males.
The median income for a household in the CDP was $54,412, and the median income for a family was $60,761. Males had a median income of $36,181 versus $25,337 for females. The per capita income for the CDP was $23,801. About 2.9% of families and 5.1% of the population were below the poverty line, including 4.7% of those under age 18 and 2.5% of those age 65 or over.