Army Corps targets earlier refill for Lake Washington

USACE/Seattle District
Published April 30, 2024
Aerial photo of Lake Washington Ship Canal and Hiram M. Chittenden Locks, showing the small and large locks in Seattle, Washington.

Aerial photo of Lake Washington Ship Canal and Hiram M. Chittenden Locks, owned and operated by the U.S. Army Corps of Engineers, Seattle (Courtesy photo)

U.S. Army Corps of Engineers officials advise private and commercial interests along Lake Washington Ship Canal and in Lakes Washington and Union to expect earlier high water than in previous years.

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

Water managers are responding to the statewide drought declaration, by filling Lake Washington nearly a month early with full refill expected in early May. Snowpack is lower than normal, and the National Weather Service Climate Prediction Center’s seasonal forecasts show a warmer and drier summer ahead.

“Targeting earlier refill makes it much more likely that the lake will reach its normal full elevation target of 22 feet,” said Seattle District’s Western Washington Senior Water Manager Kyle Comanor. “Refilling the lake to this elevation will help meet increased summer water use, providing water necessary for fish passage, navigation and salinity control.”

Water use for the large lock this summer will be higher due to the center gate replacement project - which makes a full refill even more important this year.

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 Seattle District Reservoir Control Center website.

For more information about activities at the Locks, visit our public website, follow us on Facebook and X.


Nicole L. Celestine

Release no. 24-010