Mariaville Lake is a census-designated place (CDP) in Schenectady County, New York.

As of the census[6] of 2000, there were 710 people, 258 households, and 188 families residing in the CDP.

There were 341 housing units at an average density of 60.3 per square mile (23.3/km2).

There were 258 households, of which 38.0% had children under the age of 18 living with them, 58.5% were married couples living together, 9.3% had a female householder with no husband present, and 27.1% were non-families.

22.5% of all households were made up of individuals, and 7.4% had someone living alone who was 65 years of age or older.