Liberty Reservoir, also known as Liberty Lake, is located in the Patapsco region of the Chesapeake Bay watershed within Maryland’s Baltimore suburbs. The watershed covers portions of both Baltimore and Carroll Counties. This area was the former site of the Melville Woolen Mills. The land was purchased from the Melville family by the city of Baltimore in 1954 for use as a public water supply. At the time it was the largest land purchase in state history. When the city constructed the dam, the entire mill town, including factories, was left intact and flooded to create the reservoir. Today Liberty Lake collects water from a 163 square mile drainage area that includes eastern Carroll County and southwestern Baltimore County. Water from the reservoir flows by gravity through a 12.7-mile long, 10-foot diameter tunnel to the Ashburton Water Filtration Plant for treatment before reaching suburban Baltimore.