oxygen-rich Cape Cod Bay water and it became a stagnant freshwater pond. These conditions resulted in midge outbreaks, fish kills, and a proliferation of exotic species. After almost 140 years of impoundment, no native salt marsh vegetation was left in or around Pilgrim Lake. Instead, the floodplain was taken over by a non-native cattail species and some highly invasive plants like purple loosestrife (Lythrum salicaria) and common reed (Phragmites australis). Restoration After an oxygen depletion and fish kill in 2001, the town of Truro and the National Park Service began to explore options to restore the estuary. They focused on a drainage pipe connecting Pilgrim Lake to Cape Cod Bay. This ~, diameter culvert had been fitted with clapper valves to allow freshwater to drain out of Pilgrim Lake, but prevented marine tides from flowing back into the system. To restore partial tidal exchange and to improve water quality, they opened the clapper valves, which have remained open continuously since November 2002. Despite limits on tidal exchange imposed by the pipe's small diameter, and the distance that it travels underground, they have observed a substantial response in the recovery of salinity and estuarine biota. In June 2008, Pilgrim Lake was officially renamed back to its original moniker, East Harbor. The 720-acre East Harbor system, includes Moon Meadow, Salt Meadow and the East Harbor lagoon. References Ports and harbors of Massachusetts Truro, Massachusetts Cape Cod National Seashore Geography of Barnstable County, Massachusetts Transportation in Barnstable County, Massachusetts