| East Branch Penobscot River | |
|---|---|
| Origin | Maine |
| Mouth | Penobscot River |
| Basin countries | United States |
| Length | 75 miles (121 km) |
| Source elevation | 1,000 feet (300 m) |
| Mouth elevation | 240 feet (70 m) |
| Left tributaries | Seboeis River |
The East Branch Penobscot River is a 75.3-mile-long (121.2 km)[1] tributary of Maine's Penobscot River. From its source () in Maine Township 7, Range 11, WELS, in Piscataquis County, the river runs 17 miles (27 km)[1] southeast to Grand Lake Matagamon in the northeast corner of Baxter State Park. From Grand Lake Dam, the river runs 48 miles (77 km)[1] south to its confluence with the Penobscot's West Branch in Medway, Penobscot County.