From its source (46°16′01″N 69°12′08″W / 46.2670°N 69.2023°W / 46.2670; -69.2023 (East Branch Penobscot River source)) in Maine Township 7, Range 11, WELS, in Piscataquis County, the river runs 17 miles (27 km)[1] southeast through the North Maine Woods to Grand Lake Matagamon reservoir, 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 West Branch Penobscot River in Medway, Penobscot County.

The dam was built at the outlet of First Lake, and flooded vast expanses of low-lying land extending upstream to include Second Lake.

The shallow water habitat created by the dam is more suitable for yellow perch, fallfish, and longnose sucker rather than for trout.

This article related to a river in Maine is a stub.