Lake Washington annual summer refill underway

Published May 22, 2023

U.S. Army Corps of Engineers officials continue the remainder of the annual refill of Lake Washington to elevation 22 ft the week of May 22.

Private and commercial maritime interests along Lake Washington Ship Canal and in Lakes Washington and Union should expect to reach the 22-foot target refill elevation in early June.

Vessel owners should closely monitor lake elevations and adjust mooring lines as necessary.

Water managers began Lake Washington's annual summer refill operations Feb. 15, 2023, and the Lake has been refilled to 21.85 ft as of April 30. Refilling the lake to 22 feet will help meet increased summer water use, providing water necessary for fish passage, navigation, and salinity control.

The official lake level is measured at the Locks. The 22-foot target elevation is referenced to the local project datum, equivalent to 18.75 feet referenced to the North American Vertical Datum of 1988.

Lake Washington and Lake Union levels may vary due to natural gradient between the lake and the Locks, or wind that can push the lake levels up for short durations. Depending on conditions, the lake may remain at the maximum target elevation through June and July.

For current information about activities at the Locks, follow the Locks on Facebook ( and Twitter at @ChittendenLocks) / Twitter


Nicole L. Celestine

Release no. 23-014