The Penobscot Bay Watershed
The Penobscot Bay watershed includes the ~8,900 square miles of land that drains into Penobscot Bay, as well as the Bay itself, which encompasses an estimated 1,070 square miles and includes approximately 1,700 islands, rock, and ledges. The Bay is shaped like an elongated triangle and is over 45 miles wide at its mouth and 37 miles long. The West Branch of the Penobscot River rises near Penobscot Lake on the Maine/Quebec border; the East Branch of the Penobscot River begins at East Branch Pond near the headwaters of the Allagash River. The Penobscot Bay drainage includes the Penobscot River, Bagaduce River, Passagassawakeag River, Weskeag River, Goose River, Ducktrap River, and Little River watersheds.
Penobscot Bay is an integral part of daily life for residents and visitors alike in coastal Maine, and the uses of this waterbody, as well as the rivers that feed into it, are wide-ranging. The Bay is critical to the economies of Maine’s coastal towns, as well as the entire state in its entirety due to tourism and commercial fishing. Midcoast Maine’s coast and islands rely on tourism, drawing local people, summer residents, and tourists with recreational opportunities, including paddling, sailing, sport fishing, whale watching, and swimming.
Commercial fisheries have been an indispensable part of Maine’s economy for centuries, and the fisheries of Penobscot Bay include lobster, mussels, finfish, and oysters. There are many places in the Bay that are closed to shellfish harvesting due to either bacteria levels from sewage pollution, or legacy mercury contamination despite the existence of suitable habitat and the presence of fish populations.
The Bay serves as a shipping corridor and is home to marine ports for bulk and dry cargo, as well as chemicals and petroleum products in Searsport, Bangor, and Bucksport. The Bay is also utilized for transportation for both residents of the islands (Vinalhaven, Islesboro, North Haven, etc.) as well as tourism.
The Penobscot River is home to 11 diadromous (migratory) fish species: American shad, Atlantic salmon, alewife, blueback herring, shortnose sturgeon, Atlantic sturgeon, sea lamprey, American eel, striped bass, rainbow smelt, and tomcod. Three of these – Atlantic salmon, shortnose sturgeon, and Atlantic sturgeon – are federally listed endangered species. Most sea-run species except smelt and eels are found in numbers far below historic levels because of non-existent or inadequate fish passage facilities at the many dams along both main-stem rivers and tributaries, past pollution, and loss of habitat due to dam construction. The rivers that feed into Penobscot Bay are utilized for hydroelectric power generation and have been dammed in order to do so. While many dams remain in use today for power generation, there are also many small, historical dams no longer in use or maintained.
The rivers that feed into Penobscot Bay are utilized by municipalities as drinking water sources. The waters are also used for agricultural purposes, with dairy and potato farms concentrated in the Kenduskeag Stream watershed west of Bangor, and industrial-scale aquaculture operations proposed in Belfast and Millinocket. Most of the watershed beyond the coastline is forested, intensively harvested for pulp and saw logs, and sparsely settled. The timber and paper industries have a long history within the watershed; while many of the paper mills in the region have closed in the past decade, there are still operational mills on the main stem of the Penobscot River in Old Town, and former mills in Millinocket, Brewer and Lincoln are being redeveloped for production of biofuels, including wood pellet processing.
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