Corps of Engineers begins Lake Washington annual summer refill

Published Feb. 11, 2019

SEATTLE – U.S. Army Corps of Engineers officials will begin Lake Washington’s annual summer refill operations February 15, 2019.

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

Water managers are targeting a typical annual refill of the lake to elevation 22 feet this spring. Fill rates and target elevations vary through May based on conditions. 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 a gradual rise from the winter level of 20 feet until the 22-foot target refill elevation is reached around June 1.

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.

More information on Lake Washington’s status is available on the Corps’ Seattle District Reservoir Control Center website at

For more information about activities at the Locks, visit the Locks’ Web site at Also follow the Locks on Facebook and Twitter,

Bill Dowel

Release no. 19-005