The Back River is a 16 miles (25.7 km) waterway in coastal Maine

Maine

Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...

, in the combined estuary

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 of the Sheepscot

Sheepscot River

The Sheepscot River is a river in the U.S. state of Maine. Its lower portion is a complex island estuary with connections to the Kennebec River downstream of Merrymeeting Bay.-Route:...

 and the Kennebec

Kennebec River

The Kennebec River is a river that is entirely within the U.S. state of Maine. It rises in Moosehead Lake in west-central Maine. The East and West Outlets join at Indian Pond and the river then flows southward...

 rivers. The Back River runs from Wiscasset on the Sheepscot to Georgetown

Georgetown, Maine

Georgetown is a town in Sagadahoc County, Maine, United States. The population was 1,020 at the 2000 census. Home to Reid State Park, the town is part of the Portland–South Portland–Biddeford, Maine Metropolitan Statistical Area...

 on the Kennebec, intersecting another channel, the Sasanoa River

Sasanoa River

The Sasanoa River is an tidal channel in the Midcoast region of Maine, connecting the Kennebec River with the Sheepscot River.The Sasanoa River has two distinct sections. The western section begins at the Kennebec River opposite the city of Bath and runs east, forming the boundary between the...

, at Hockomock Bay.

Maine State Route 144 bridges the northern section of the Back River from Wiscasset to Westport Island

Westport Island, Maine

Westport Island, formerly Westport, is a town in Lincoln County, Maine, United States. In the 19th Century the island was known as Jeremysquam, a nickname islanders still use for it. The population was 745 at the 2000 census.-Geography:...

. Maine 127 bridges the narrow southern part at Arrowsic

Arrowsic, Maine

Arrowsic is a town in Sagadahoc County, Maine, United States. The population was 477 at the 2000 census. It is part of the Portland–South Portland–Biddeford, Maine metropolitan statistical area. During the French and Indian Wars, Arrowsic was site of a succession of important and...

, from Arrowsic Island to Georgetown Island.

The site of the decommissioned Maine Yankee Nuclear Power Plant is on the northern section.