Rock Island Dam
| Rock Island Dam | |
|---|---|
Rock Island Dam from Washington SR 28
|
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| Location | Chelan / Douglas counties, Washington |
| Coordinates | 47°20′32″N 120°05′41″W / 47.342155°N 120.094773°WCoordinates: 47°20′32″N 120°05′41″W / 47.342155°N 120.094773°W |
| Construction began | 1930 |
| Opening date | 1933 |
| Dam and spillways | |
| Impounds | Columbia River |
| Reservoir | |
| Creates | Rock Island Pool |
| Total capacity | 131,000 acre·ft (0.162 km3) |
| Power station | |
| Turbines | 19 |
| Installed capacity | 623.7 MW |
| Annual generation | 2,600 GWh |
Rock Island Dam is a hydroelectric dam on the Columbia River in the U.S. state of Washington. Chelan County Public Utility District'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. 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. The dam's reservoir is called Rock Island Pool.
Rock Island Dam is constructed on Columbia River basalt 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, 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).
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 passing the Project. During the spring, 1,570,495 acre feet (1.937177×109 m3) 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.
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