Rock Island Dam is a

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

on the

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

, in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

Chelan County Public Utility District The Chelan County Public Utility District, or Chelan County PUD, provides electric, water, wastewater public utility and telecommunications services in Chelan County, in north-central Washington, USA. It is organized under state statute as a non ...

's ''Rock Island Dam and Hydro Project'' was the first dam to span the Columbia, having been built from 1929 to 1933. It is located near the geographical center of Washington, about 12 miles (19 km) downstream from the city of

Wenatchee Wenatchee ( ) is the county seat and largest city of Chelan County, Washington, United States. The population within the city limits in 2010 was 31,925, and was estimated to have increased to 34,360 as of 2019. Located in the north-central part ...

. By river, the dam is 235 miles (378 km) south of the Canada–US border and 453 miles (729 km) above the mouth of the river at

Astoria, Oregon Astoria is a port city and the seat of Clatsop County, Oregon, United States. Founded in 1811, Astoria is the oldest city in the state and was the first permanent American settlement west of the Rocky Mountains. The county is the northwest corne ...

. The dam's reservoir is called

Rock Island Pool Rock Island Pool is a reservoir on the Columbia River in the U.S. state of Washington. It was created in 1933 with the construction of Rock Island Dam. The reservoir stretches from there upstream to the Rocky Reach Dam. See also * List of dams in ...

.http://pubs.usgs.gov/wdr/2005/wdr-wa-05-1/pdf/wa00103ADR2005_Figure56.pdf

Overview

Rock Island Dam is constructed on

Columbia River basalt The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental large igneous province, flood basalt province on Earth, covering over mainly eastern Oregon and Washington (state), Washington, western Idaho, a ...

similar to that which is exposed on the cliffs near the dam. These columnar basalts were formed from lava flows during the mid- to late-

Miocene Epoch The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

, some 14 to 16 million years ago. The rock is strong and durable and provides a very stable foundation for the structure. Columbia River stream flows at the Project averaged 73,700 cubic feet per second (2090 m³/s), a decrease of 37% from 2000 and 63% of the 20 year average of 116,700 cubic feet per second (3305 m³/s).

Electricity generation

The Rock Island Hydro Project generated 1,900 gigawatt-hours of electricity in 2001 — 70% of its 2000 output. Over the past 10 years the Project has averaged 2,600 gigawatt-hours per year. During 2001, Rock Island’s Second Powerhouse produced 1,800 gigawatt-hours of power, representing 95% of the Project’s total generation for the year. The 10 year average generation for the Project is 383 gigawatt-hours. Under the terms of the Rock Island Settlement Agreement, the District provides spill to improve the survival rate of juvenile

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

passing the Project. During the spring, of water was spilled during a 59-day period between April 20 and June 17. This resulted in 73,427 megawatt-hours of foregone generation valued at $13.4 million. In 1927, the Rock Island site came to the attention of the

Stone and Webster Stone & Webster was an American engineering services company based in Stoughton, Massachusetts. It was founded as an electrical testing lab and consulting firm by electrical engineers Charles A. Stone and Edwin S. Webster in 1889. In the early ...

Engineering Corporation, a Boston-based holding company that managed Puget Sound Power & Light Company. The site was recognized for its potential to provide power for the growing electrical load in the state. On December 13, 1928 an application was filed with the

Federal Power Commission The Federal Power Commission (FPC) was an independent commission of the United States government, originally organized on June 23, 1930, with five members nominated by the president and confirmed by the Senate. The FPC was originally created in 1 ...

for a preliminary permit to investigate the site. This was followed by an application for license submitted in June 1929 by the Washington Electric Company, a subsidiary construction corporation of Puget Sound Power & Light (now part of

Puget Sound Energy Puget Sound Energy (PSE) is an energy utility company based in the U.S. state of Washington that provides electrical power and natural gas to the Puget Sound region. The utility serves electricity to more than 1.1 million customers in Island, Ki ...

). The license was authorized on October 16, 1929, and on January 14, 1930, at the beginning of the

Great Depression The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagio ...

, construction started on the first dam to span the Columbia River. ROCK ISLAND DAM IS THE OLDEST DAM ON THE COLUMBIA RIVER - NARA - 548012

The development of Rock Island Dam occurred over a period of some 50 years. There were three main construction periods, each taking place about 20 years apart as the need for low-cost hydroelectric power was paramount in the region. Development began in January 1930, and the dam, powerhouse, and first four operating units were turned over to Puget Sound Power & Light Company by Stone and Webster Engineering Corporation on February 1, 1933. Work on completion of the dam, powerhouse expansion and installation of six additional units by Chelan County PUD began in July 1951 and was completed on April 30, 1953. Construction of the Second Powerhouse, with its eight turbine generators located on the west bank of the river, began on August 4, 1974. The Second Powerhouse was placed in commercial operation on August 31, 1979. Pacific Northwest River System

References

{{Authority control Buildings and structures in Chelan County, Washington Dams on the Columbia River Dams in Washington (state) Buildings and structures in Douglas County, Washington Hydroelectric power plants in Washington (state) United States local public utility dams Dams completed in 1933 Energy infrastructure completed in 1933 Gravity dams 1933 establishments in Washington (state)