| Quaddick Reservoir | |
| Location: | Thompson, Connecticut, United States |
| Type: | Reservoir |
| Inflow: | Five Mile River, Robbins Brook, Poor Farm Brook, Blackmore Brook |
| Catchment: | 35sqmi |
| Elevation: | (85 m) |
| Islands: | Green, Gould’s, Brandy Hill, Harris |
| Sections: | Lower, Middle and Upper |
| Pushpin Map: | Connecticut |
| Pushpin Map Caption: | Location in Connecticut |
Quaddick Reservoir is a man-made body of water in the town of Thompson, Connecticut. The reservoir has three sections: Lower (124 acres), Middle (203 acres), and Upper (81 acres). It originated with the completion of a dam on the Five Mile River in 1865. Quaddick State Park sits on the eastern shore of the Middle Reservoir.