The Ellsworth Power House and Dam is a hydroelectric power generation facility on the Union River in Ellsworth, Maine.[2] The dam, located just north of downtown Ellsworth, is also known as the Union River Dam,[3] and impounds the river to create Leonard Lake,[4] named for project's engineer, James Leonard.[citation needed] The powerhouse is a Renaissance Revival building located at the western end of the dam.[citation needed] The power plant, built in 1907,[3] was one of the first peaking power plants built in the state, and the hollow concrete dam is one of the highest hollow (or Ambursen-type) buttress dams ever built, having been described as "the highest power dam in New England" in 1928.[2][5] The facility was nominated for the National Register of Historic Places in 1985,[2] where it is currently listed.[3]
Description
The Ellsworth Dam is located between two bluffs which flank Maine's Union River, and rise to a height of more than 100 feet (30 m).[2] The dam consists of a series of buttresses, each set on a schist bedrock ledge, three feet thick, and spaced about 15 feet (4.6 m) apart, which provide support for two large slabs of steel-reinforced concrete that span the river between the bluffs.[2][5] The dam is 71 feet (22 m) in height, with a spillway 60 feet (18 m) long.[2] The schist ledge ensures the longevity of the dam.[clarification needed][5]
The power station is located at the base of the dam on the west bank of the river.[2] It is a 1+1⁄2-story structure built out of concrete blocks, with a red tile gabled roof.[2] The Renaissance Revival[citation needed][clarification needed] structure has round-arch windows which are connected by a stone belt course, and there are Palladian windows in the gable ends.[2] An addition on the building's rear was built with similar styling.[2]
The Ellsworth Dam produces 29,907 megawatt-hours per year as of 2012,[4] and is licensed to supply about 30,000 megawatt-hours per year, which is 1% of Maine's hydropower.[3] It is one of the 118 power-generating dams in Maine as of 2016.[3] The flow of water at the Ellsworth Dam is controlled by the Graham Lake Dam, which created Graham Lake.[4]
History
The power station was built in 1907 by the Bar Harbor and Union River Power Company, to designs by its engineer, James Leonard.[2] The company was merged in 1925 into the Bangor Hydro-Electric Company,[2] now part of Emera.[citation needed] Later, the plant was sold to Penobscot Hydro[clarification needed], and then to PPL in 1999[clarification needed].[4] The plant was acquired by Black Bear Hydro in 2009 from PPL,[4] and sold to Brookfield Partners in 2014.[citation needed]
The dam was in the process of being relicensed as of 2012; its most recent permit, issued by the Federal Energy Regulatory Commission in 1987, was due to expire in 2017.[4] However, public concern about fish passage and water quality, caused the Federal Energy Regulatory Commission to delay issuing a new permit.[citation needed] The new expiration date is April 2020.[citation needed]
(The dam is no longer hollow. During the 1990s. the FERC required installation of post-tensioned anchors deep into ledge and the filling of the hollow dam with concrete, in order to increase dam safety.)[citation needed]