The Grand Coulee Dam is perhaps the most magnificent dam on the mighty Columbia River in Washington. This massive structure is listed by the American Society of Civil Engineers as one of seven civil engineering wonders of the world. It took eight years to build the dam and thousands of men and women. A 150 mile long lake was created by the dam and the water in it is used as a water supply for farms and cities and for recreation. The dam is an important source for electricity used in the Pacific Northwest.