Blackwater River (Maine)
 The Blackwater River is a 7.1-mile-long (11.4 km) river in Aroostook County Maine. From the confluence of its North Branch and South Branch (46°29′14″N 68°15′07″W) in Squa Pan Township (Township 10 Range 4 WELS) the river runs west to St. Croix Stream in Masardis. Via St. Croix Stream and the Aroostook River the Blackwater River is part of the St. John River watershed.