Lake Chelan is a narrow, 50.5 miles (81.3 km) long lake in Chelan County, north-central Washington state, U.S. It is the largest natural lake in the state by any measure. With the completion of Lake Chelan Dam in 1927, the elevation of the lake was raised up to 21 feet (6.4 m). Two communities lie on the southern end of the lake, and a third sits at the far north end, providing a gateway to the North Cascades National Park.