The Penobscot River rises in several tributaries northwest of Moosehead Lake near Maine’s northwestern border with Quebec. These tributaries flow nearly 100 miles southeasterly to the main river in Medway. The main river flows southerly, through Bangor, for 93 miles and empties into Penobscot Bay, between Stockton Springs and Castine. The navigable section of the river is the approximately 30-mile reach between Bangor and Castine. Of this section, Corps’ work covers the channel’s 20 miles between Bangor and Bucksport, which passes through the towns of Brewer, Hampden, Orrington, Winterport, and Frankfort. Because the last 10 miles of the river, between Frankfort and Castine, is naturally deep, dredging was not required by the Corps. This 10-mile section of channel passes through the towns of Verona, Prospect, Orland, Penobscot, and Stockton Springs

Small tankers transporting petroleum and asphalt products to Bangor and other communities make up the river’s principal traffic. Recreational and commercial fishing craft primarily use the Penobscot River’s lower reaches.

Initial work on the Penobscot River was completed in 1879 and involved dredging to a depth of 12 feet and removing obstructions in the 3.5-mile reach below Bangor. The mouth of Kenduskeag Stream in Bangor was also dredged at this time, but in 1947 this stream was declared non-navigable and that part of the project was abandoned.

The most recent work on the Penobscot River, completed in 1913, involved:

• Deepening the natural channels at Lawrence Cove in Bucksport and Frankfurt Flats downstream of Winterport to 22 feet.
• Straightening, widening, and deepening to 15 feet the channel between Crosby Narrows in Hampden and Steams Mill in Brewer.
• Deepening the channel at Bangor to 14 feet. Also, about 2,000 feet of the channel along the Bangor and Brewer waterfronts was widened by an additional 100-300 feet.