Rock Island Dam is a hydroelectric dam on the Columbia River, in the U.S. state of Washington. Built from 1929 to 1933, it was the first dam to span the Columbia. It is located near the geographical center of Washington, about 12 miles (19 km) downstream from the city of Wenatchee. By river, the dam is 235 miles (378 km) south of the Canada–U.S. border and 453 miles (729 km) above the mouth of the river at Astoria, Oregon. The dam's reservoir is called Rock Island Pool.