The Eklutna Dam, also referred to as the New Eklutna Dam or Upper Eklutna Dam, is an

embankment dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface ...

on the Eklutna River about northeast of

Anchorage Anchorage, officially the Municipality of Anchorage, is the most populous city in the U.S. state of Alaska. With a population of 291,247 at the 2020 census, it contains nearly 40 percent of the state's population. The Anchorage metropolita ...

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. The primary purpose of the dam is

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

power generation and it supports a 47 MW power plant. It was first completed in 1929 but was rehabilitated or rebuilt on several occasions over its history. Ownership of the dam and power plant is shared by Chugach Electric and Matanuska Electric.

Background

The original dams and power plant was the idea of businessman Frank Reed. It was constructed by the Anchorage Light and Power Company between 1927 and 1929 atop a natural

landslide dam A landslide dam or barrier lake is the natural damming of a river by some kind of landslide, such as a debris flow, rock avalanche or volcanic eruption. If the damming landslide is caused by an earthquake, it may also be called a quake lake. Some ...

in the Eklutna Valley. It regulated the river to the Lower Eklutna Dam which diverted water into the Old Eklutna Power Plant. The lake dam was rebuilt and improved in 1941 after the previous structure failed. During this same year, the population in Anchorage increased greatly with the onset of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. To cope with increasing power demand, the

United States Bureau of Reclamation The Bureau of Reclamation, formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and operatio ...

proposed the Eklutna Project. It included raising the dam and installing a new power plant opposite Goat Mountain to the north, along the

Knik River The Knik River ( Dena'ina: ''Skitnu''; Ahtna: ''Scitna’'') is a river in the U.S. state of Alaska. Its source is at Knik Glacier, from which it flows northwest and west and empties into the head of Cook Inlet's Knik Arm, near the mouth o ...

. The

United States Congress The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, ...

authorized the project on 31 July 1950. Construction began in 1951 and raising the dam commenced the following year. The first generator was commissioned on 8 January 1955, the second and last on 1 April 1955. On 1 July 1955 the entire project was complete. The Great Alaska earthquake in March 1964 caused significant damage to the dam, particularly the water intake for the power plant. The intake shifted towards the lake and frozen

alluvium Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

beneath and near the dam's

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

densified, creating voids. Later, in July of the same year, as the ground thawed, two cracks formed near the spillway and portions of the dam filled the void. The dam was deemed unsafe and a taller embankment dam was constructed just downstream. Construction and rehabilitation was carried out until 1966. In 1997 the Alaska Power Authority sold the dam and power plant to Anchorage Municipal Light and Power, Chugach Electric Association and Matanuska Electric Association for US$6 million. Chugach Electric acquired Anchorage Municipal Light and Power in 2020.

Design

The dam is tall and long. It is filled with sand, gravel and earth and its crest is above sea level. The reservoir created by the dam, Eklutna Lake, covers and is long. At an elevation of , the reservoir holds of water. To connect the reservoir and power plant, there is a diameter, long

penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is of Scots origin, and was inherited from the earlier technology of mill pond ...

which starts at the intake, located on the northwest corner of the lake. From the intake, water rushes down the penstock where it reaches two 23.5 MW

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The pro ...

-generators. Water used by the power plant is then discharged into the Knik River.

References

{{Commons category, Eklutna Power Plant Dams in Alaska Embankment dams Dams completed in 1955 1955 establishments in Alaska Energy infrastructure completed in 1955 Hydroelectric power plants in Alaska Buildings and structures in Anchorage, Alaska United States local public utility dams