Lake Washington Annual Summer Refill Underway

USACE, Seattle District
Published May 17, 2022

U.S. Army Corps of Engineers officials began Lake Washington’s annual summer refill operations Feb. 15, 2022.

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

The Lake has been gradually refilled to 21.85 ft as of May 13. Water managers are targeting a typical annual refill of the lake to elevation 22 feet later this spring. Refilling the lake to 22 feet will help meet increased summer water use, providing water necessary for fish passage, navigation, and salinity control.

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.

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, visit the Locks’ Web site at or follow the Locks on Facebook and Twitter: and





Nicole L. Celestine

Release no. 22-006