Hidden Valley is a private residential community in Dearborn County, Indiana, United States. For statistical purposes it is a census-designated place (CDP), with a population of 5,387 at the 2010 census, up from 4,417 at the 2000 census. Setting The Hidden Valley community is located in southeastern Indiana and is built around Hidden Valley Lake, an impoundment on Doublelick Run, a small stream which flows southeast to the Ohio River. There are of common grounds and recreational areas. The lake occupies , with recreational opportunities that include fishing, boating and water skiing. A marina is located at the southeastern tip of the lake. History The community and lake were built by land developer James Jacob Rupel, who was active in the Greater Dayton area and Indiana for over 50 years and the former owner of Centre City Building and the Carillon House in downtown Dayton. He was the developer of Hidden Valley Lake, several subdivisions near Rocky Fork State Park in Highland County, Ohio, the Valley Woods community in Greendale, Indiana, and the Country Squire Lakes community in North Vernon, Indiana. Geography Hidden Valley is located in eastern Dearborn County at (39.166281, -84.841570), within Miller and Lawrenceburg townships. It is bordered to the south by the city of Greendale and to the east by the Ohio state line. Downtown Cincinnati is to the east. According to the United States Census Bureau, the Hidden Valley CDP has a total area of , of which is land and , or 6.12%, is water. Demographics As of the census of 2000, there were 4,417 people, 1,542 households, and 1,318 families residing in the CDP. The population density was . There were 1,599 housing units at an average density of . The racial makeup of the CDP was 97.83% White, 0.27% African American, 0.18% Native American, 0.50% Asian, 0.07% Pacific Islander, 0.34% from other races, and 0.82% from two or more races. Hispanic or Latino of any race were 0.82% of the population. There were 1,542 households, out of which 40.9% had children under the age of 18 living with them, 78.3% were married couples living together, 4.7% had a female householder with no husband present, and 14.5% were non-families. 10.7% of all households were made up of individuals, and 2.9% had someone living alone who was 65 years of age or older. The average household size was 2.86 and the average family size