The image of the Union River Power House and Dam is taken from along the eastern bank of the Union River in Ellsworth looking west.

Bar Harbor and Union River Power Company owned the power house and dam. The structure was 72 feet in height, 500 feet in length; its construction formed Leonard Lake.

The dam's construction was contracted for on February 10, 1907 and was completed by the Ambursen Hydraulic Construction Co. of Boston, Massachusetts.

Before any concrete could be poured, almost 3,000 yards of solid rock had to be removed. The dam is constructed of steel-reinforced concrete while the power house is composed of concrete blocks, the roof waterproofed with asphalt and shingled with red Italian tiling.

Construction took five months and five days. The Union River Power House and Dam first went into service to produce hydroelectric power on January 8, 1908.

The power house depicted here took extensive damage and was washed away in the flood of April 29 1923. However, repairs were made and the Union River Dam is still in service (2013), owned by the Bangor Hydroelectric Company.