Lower Granite Dam facts for kids
Quick facts for kids Lower Granite Dam |
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View from the northwest
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Location of Lower Granite Dam in USA#Washington
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| Country | United States |
| Location | Garfield / Whitman counties, Washington |
| Coordinates | 46°39′38″N 117°25′41″W / 46.66056°N 117.42806°W |
| Construction began | July 1965 |
| Opening date | June 1975 |
| Construction cost | $624,098,663 |
| Operator(s) | U.S. Army Corps of Engineers |
| Dam and spillways | |
| Type of dam | Gravity dam |
| Impounds | Snake River |
| Height | 100 ft (30 m) |
| Length | 3,200 ft (980 m) |
| Spillway type | Service, gate-controlled |
| Spillway capacity | 850,000 cu ft/s (24,000 m3/s) |
| Reservoir | |
| Creates | Lower Granite Lake |
| Total capacity | 440,200 acre⋅ft (0.543 km3) |
| Surface area | 8,900 acres (36.0 km2) |
| Normal elevation | 741 ft (226 m) |
| Power station | |
| Type | Run-of-the-river |
| Turbines | 6 × 135-155 MW units |
| Installed capacity | 810 MW |
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The Lower Granite Lock and Dam is a big concrete dam in the northwestern United States. It sits on the lower Snake River in southeastern Washington. This dam connects Whitman and Garfield counties. It opened in 1975. The dam is about 22 miles south of Colfax. It's also about 35 miles north of Pomeroy.
The Lower Granite Dam is part of a larger system of dams. These dams are in the Columbia River Basin. The United States Army Corps of Engineers built and runs them. The power made here goes to homes and businesses. The Bonneville Power Administration helps share this power.
Behind the dam is Lower Granite Lake. This lake stretches about 39 miles east to Lewiston, Idaho. The lake helped Lewiston become a port city. The first barge carrying wheat left Lewiston on August 9, 1975. It traveled 374 miles to Portland.
Lake Bryan is another lake formed by a dam. It was created by the Little Goose Dam. Lake Bryan runs about 37 miles downstream from the Lower Granite Dam.
Building the Dam
Building the Lower Granite Dam started in July 1965. Work stopped less than two years later because there wasn't enough money. Construction began again in 1970. Workers poured the first concrete in 1971.
The main part of the dam and three power generators were finished in 1975. A special opening ceremony happened on June 19, 1975. Three more generators were added by May 1978. This brought the dam's total power to 810 megawatts. It could even make up to 932 megawatts when needed.
The dam has a spillway with eight gates. This spillway is about 512 feet long. A large navigation lock was also built. This lock helps boats pass through the dam. It is 86 feet wide and 674 feet long.
Just below the dam, a place called Boyer Park was built. The Corps of Engineers opened this park in April 1973.
Fish and the Dam
The Lower Granite Dam is the highest dam on the Snake River that has a fish ladder. A fish ladder helps adult salmon and steelhead swim upstream. They use it to reach their spawning grounds.
Some groups want this dam and three others removed. They believe the dams harm fish like chinook and sockeye salmon. These fish are either threatened or endangered. The Corps of Engineers knew in 1971 that the dam would affect wildlife.
In 2008, many Sockeye Salmon returned to the Columbia River. This was a happy surprise. It gave hope for more salmon runs at Lower Granite. Experts weren't sure why more salmon returned.
The Corps of Engineers has added new tools to the dam. These include removable spillway weirs. They hope these tools make the dam safer for young salmon. There is also a special facility that collects young salmon. It gathers them so they can be moved downstream by barge.
Other Dam Ideas
In 1962, Congress approved a fifth dam on the lower Snake River. It was called the Asotin Dam. It was planned to be a few miles south of Lewiston. People worried about its impact on nature and recreation. The project was stopped in 1980.
In 1988, Asotin County tried to restart the project. But Congress quickly blocked it. President Ronald Reagan signed a law on November 17, 1988. This law banned building future dams there.
Other dams were also planned further upstream. These included the High Mountain Sheep Dam and the Nez Perce Dam. But these dams were never built either.
Road Across the Dam
After the September 11 attacks in 2001, the road over the Lower Granite Dam was closed. It stayed closed for more than six years. The road finally reopened for weekend traffic in May 2008.
A sand dune area below the dam was popular. It was a favorite spot for college students. Students from Washington State University and the University of Idaho often visited.
