Grand Coulee is the largest electric power producing facility
and the largest concrete structure in the United States, and
is the fifth largest producer of hydroelectricity in the world.

The Grand Coulee Dam is almost a mile long at 5223 feet (1586 m).
The spillway is 1,650 feet(503 m) wide and is 550 feet (168 m)tall.

Average release: 110,000 ft³/s (3,100 m³/s)
4 power plants, 33 generators
Installed generating capacity: 6809 MW

from: Wikipedia