Lake Washington is a lake in the US state of Washington. It is next to the city of Seattle. Seattle is on the west side of the lake, Lake City, Bothell, and Kenmore to the north, Kirkland and Bellevue to the east, and Renton to the south. Mercer Island is in the south end of the lake. The deepest part of the lake is deep. The lake is above sea level. It is a fresh water lake. On a few days of the year are people allowed to fish for salmon in the lake.