This postcard depicts Leonard Dam, officially called the Union River Power House and Dam during the flood of 1923. The power house and dam were owned by the Bar Harbor and Union River Power Company. The structure measured seventy-two feet in height, five hundred feet in length, and its construction formed Leonard Lake.

The dam's construction was ordered on February 10th, 1907 and was completed by the Ambursen Hydraulic Construction Co. of Boston, Massachusetts. Before any concrete could be poured, almost three thousand 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, and the roof is waterproofed with asphalt and shingled with red Italian tiling. The total construction period lasted five months and five days. The Union River Power House and Dam first went into service to produce hydroelectric power on January 8th, 1908.

April of 1923 had significantly more rain than is typical of the area. On Saturday, April 28th, 4.6 inches of rain fell in about twenty-four hours along the entire Union River watershed. To protect cottages from flooding, a dam further upriver at the foot of Green Lake, raised its gates. This pushed the Leonard Dam over the breaking point. Water levels surpassed 108 feet, or four feet above the maximum level that the dam was constructed for. The dam failed sweeping away Ellsworth's Union River Bridge along with numerous businesses, boats, and other personal property. The total damage came in at four hundred thousand dollars. Of that, one hundred and twenty-five thousand dollars accounted for the losses suffered by the dam and power house infrastructure alone.

The power house is depicted here taking extensive damage and was ultimately washed away. However, repairs were made and the Leonard Dam, or Union River Power House and Dam, is still in service today (2013), and is owned by the Bangor Hydroelectric Company.