[4] The Portage River was first dredged in 1860, and the need for a light to mark the mouth of the waterway was quickly obvious.

In 1913, work began on a new harbor inside the waterway, and in 1917 Congress appropriated $100,000 for a suite of new navigational aids, including this lighthouse to mark the outer end of the entrance way.

[6] The Keweenaw Waterway Lower Entrance Light is located at the offshore end of a breakwater extending southward from shore at the mouth of the Portage River.

[7] It is a well-preserved example of the typical architecture and engineering methods used to construct lighthouses in the Great Lakes in the time period in which it was built.

A rectangular double doorway facing the concrete pier's rooftop deck is in one side of the room.

[7] The light tower on top of the machine room is a white-painted octagonal steel structure approximately 30 feet tall.

Eight 12-inch wide stylized Tuscan order pilasters are located at the corners of the octagon, and an architrave, frieze, and cornice encircle the edge of the lip above.