Grand Coulee Dam is one of the largest concrete structures ever built.

It contains about twelve million cubic yards of concrete, which is enough to build a standard 16 foot wide highway from Seattle to New York City to Houston to San Diego and then back to Seattle.

The dam is 5,228 feet long and 550 feet high. Below is a timeline showing the construction and development history of the dam and its related facilities.

1933

Work on the dam begins.

1935

Congress authorizes development of Grand Coulee Dam and the Columbia Basin Project.

1941

Grand Coulee Dam is essentially complete. The Left Power Plant begins to operate and power generation is immediately used to support the energy intensive needs of World War II. The foundations are complete for the Right Power Plant and Pumping Plant.

1942

With the closing of the gates, the waters behind the dam rise 380 feet. The reservoir (called Franklin D. Roosevelt or Lake Roosevelt for short) extends 150 miles north, and provides over 630 miles of shoreline.

1946

Construction of Grand Coulee Pumping Plant, which pumps water from Lake Roosevelt to Banks Lake to support irrigation, begins.

1951

Six 65,000-horsepower pumps are installed to meet initial irrigation needs.

1951

The last of eighteen, 108,000-kilowatt units is installed and the Left and Right Power Plants are considered complete.

1952

Banks Lake is filled, delivering the first irrigation water.

1967

Construction of the Third Power Plant begins.

1975

The first of six units in the third power plant begins generating electricity.

1980

The sixth unit for the Third Power Plant becomes operational, completing a 13 year project that increased the amount of power generation capacity by 3,900,000 kilowatts.

For further information, visit the Grand Coulee Dam website and the Operations page of this website.