The state park was once the site of Thompson's town farm where elderly residents of the village spent their reflective years. Prior to that, it had been a fishing area of the Nipmuck Indians. In 1866 the town of Thompson granted the right to flow what was then Kings Pond to a higher level creating Quaddick Reservoir. The reservoir was heavily used as a source of power as well as water for processing textile materials in the plants in Killingly. In 1951, Quaddick was designated a state park after originally being developed as a Forestry recreation area.