| South Branch Blackwater River | |
|---|---|
| Origin | Maine |
| Mouth | Blackwater River |
| Basin countries | United States |
| Length | about 9 miles (14 km) |
| Mouth elevation | 590 feet (180 m) |
The South Branch Blackwater River is an 8.9-mile-long (14.3 km)[1] river in Aroostook County, Maine. From its source () in Maine Township 9, Range 3, WELS, the stream runs northwest to its confluence with the North Branch to form the Blackwater River in Squa Pan Township (T. 10, R. 4, WELS). Via the Blackwater River, St. Croix Stream, and the Aroostook River, the South Branch is part of the St. John River watershed.