Quabbin Reservoir
 is one of the largest
 man-made public 
water supplies in
 the United States.
 Created in the 
1930s by the 
construction of
 two huge
earthen dams, the reservoir is fed by
the three branches
of the Swift River, and seasonally by 
the Ware River.
 Quabbin's water covers 39 square 
miles, is 18 miles
 long and has 181 miles of shoreline.
 When full,
Quabbin holds 412 billion gallons of water.