Lake Monticello is a census-designated place (CDP) in Fluvanna County, Virginia, United States. The population was 6,852 at the 2000 census. The community is centered on a lake of the same name, which is formed by a dam on a short tributary of the nearby Rivanna River. Lake Monticello is part of the Charlottesville Metropolitan Statistical Area.
According to the United States Census Bureau, the CDP has a total area of 9.4 square miles (24.2 km²), of which, 8.8 square miles (22.7 km²) of it is land and 0.6 square miles (1.5 km²) of it (6.10%) is water.
There were 2,754 households out of which 32.1% had children under the age of 18 living with them, 70.8% were married couples living together, 6.7% had a female householder with no husband present, and 20.3% were non-families. 15.8% of all households were made up of individuals and 5.7% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 2.77.
In the CDP the population was spread out with 23.6% under the age of 18, 3.7% from 18 to 24, 31.0% from 25 to 44, 23.4% from 45 to 64, and 18.3% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 92.6 males. For every 100 females age 18 and over, there were 89.3 males.
The median income for a household in the CDP was $55,556, and the median income for a family was $63,641. Males had a median income of $43,319 versus $30,332 for females. The per capita income for the CDP was $25,226. About 1.2% of families and 1.8% of the population were below the poverty line, including 1.1% of those under age 18 and 1.3% of those age 65 or over.