Cutler Park Reservation is a state-owned nature preserve and public recreation area that lies between Route 128/I-95 and the Charles River in Needham, Massachusetts. The state park's 772 acres (312 ha) contain the largest remaining freshwater marsh on the middle Charles River. Parts of its major trail run directly through the marsh via boardwalks; over 100 species of birds have been sighted here. The park is part of a plan by the Town of Needham to connect 18 public areas by 35 proposed trails. It is managed by the Massachusetts Department of Conservation and Recreation.