Rock Island Dam is a hydroelectric dam on the Columbia River in the U.S. state of Washington. Chelan County Public Utility District's Rock Island Dam and Hydro Project was the first dam to span the Columbia, having been built from 1929 to 1933. 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) below the Canadian border and 453 miles (729 km) above the mouth of the river at Astoria, Oregon.