GRAND COULEE DAM

a large dam on the Columbia River in the US state of Washington . It was completed in 1942 and made larger in the 1980s. It was built to produce electricity from water power. The dam is 550 feet/168 metres high and 4 173 feet/1 273 metres long. It holds back the waters of Franklin D Roosevelt Lake, one of the largest US reservoirs (= places where water is stored for use).