Griffy Reservoir, commonly known as Lake Griffy, is a reservoir in the city of Bloomington, Indiana. Created by a dam on Griffy Creek in the 1920s, the reservoir used to serve as the main source of drinking water for Bloomington for several decades, until that role was taken over by the larger Lake Lemon and Lake Monroe in the 1950s.

Bloomington is a city in and the county seat of Monroe County, Indiana, United States. The population was 79,168 at the 2020 census. It is the seventh-most populous city in Indiana and the fourth-most populous outside the Indianapolis metropolitan area. It is the home of Indiana University Bloomington, the flagship campus of the Indiana University system. Established in 1820, IU Bloomington enrolls over 45,000 students.