SEATTLE -- U.S. Army Corps of Engineers officials anticipate Lake Washington’s level could drop below 20 feet this summer for the first time since October 1987 and are taking proactive steps to conserve water during this year’s unprecedented drought conditions.
Current projections indicate lake levels could fall below 20 feet as early as August due to exceptionally low water inflows and operational restrictions of the small lock operations, with further declines expected into September and/or October. USACE officials are adhering to water conservation measures at the Hiram M. Chittenden Locks, also known locally as the Ballard Locks.
One of the most immediate changes impacts recreational boaters. To maximize lockage efficiency and reduce water loss, the Corps is increasing the number of vessels per lockage cycle. As a result, recreational vessels may experience delays of up to one hour as lock operators wait to group additional boats together or pair them with commercial vessels.
“These actions are necessary to help preserve water for multiple critical uses throughout the system,” said Kyle Comanor, Senior Water Manager for the Seattle District. “This year presents serious challenges, and we are balancing water conservation to minimize impacts to commerce, fish passage, and the public.”
The Corps typically maintains Lake Washington between 20 and 22 feet, measured at the Chittenden Locks. Water levels are lowered to around 20 feet each winter, then refilled each spring to 22 feet by late May or early June to support summer demands, including navigation, fish migration, and salinity control.
Due to early-season drought indicators, Corps water managers accelerated this year’s refill process. The lake reached a peak elevation of 22.00 feet in late May. But historic low snowpack and extremely dry spring conditions along with operational restrictions have caused water levels to drop more rapidly than normal, already approaching mid-summer levels at just below 21 feet.
In addition to lockage changes, the Corps began conserving water this week by limiting flow through the juvenile salmon (smolt) flumes, which were installed in April. One of the two spring-installed flumes remains fully open to support fish passage into Puget Sound. Starting today the other flume will be open only during morning hours with the potential to be fully closed before the end of the month if conditions warrant it.
Floating homeowners, marina users, and vessel owners on Lake Washington, Lake Union, and the Ship Canal are strongly encouraged to prepare for further lake level declines. A recommended preparation level is between 19.5 and 20 feet. The record low lake level is 18.35 feet, set in 1958.
The National Weather Service and state officials have documented several months of record-low streamflow across much of Washington. Governor Ferguson expanded the state's drought emergency to include King County in June.
Corps officials continue to monitor conditions closely and may implement additional measures as necessary. Boaters and waterfront property owners are encouraged to follow updates via the Seattle District website and social media channels.
About the Hiram M. Chittenden Locks
Located in Seattle’s Ballard neighborhood, the Hiram M. Chittenden Locks have been operated by the U.S. Army Corps of Engineers since 1917. The Locks are essential infrastructure connecting Lake Washington’s freshwater system to Puget Sound, supporting navigation, flood risk reduction, fish migration, and water quality for the region.