The Quabbin Reservoir is the largest inland body of water in Massachusetts, United States, and was built between 1930 and 1939. Along with the Wachusett Reservoir, it is the primary water supply for Boston, 65 miles (105 km) to the east, and 40 other cities and towns in Greater Boston. The Quabbin also supplies water to three towns west of the reservoir and acts as backup supply for three others.By 1989, it supplied water for 2.5 million people, about 40% of the state’s population at the time. I