SEATTLE -- U.S. Army Corps of Engineers officials anticipate low inflows to Lake Washington this summer and are taking steps to conserve water to reduce the likelihood of the lake level dropping below 20.0 feet.
Current forecasts indicate a 30% chance that, under normal operations, the lake could drop below an elevation of 20 feet by the end of September with water levels staying low until the rain returns. To reduce the chance of dropping below 20.0 feet, USACE will conserve water releases while meeting summer requirements.
Conditions this spring and early summer have been dry. The Washington Department of Ecology issued a Drought Emergency Declaration for the Cedar watershed on June 5, due to precipitation, snowpack, and soil moisture deficits; early and rapid snowmelt; and warmer than normal temperatures with dryer than normal precipitation. The normal May precipitation in Seattle is 2.16 inches, but only 1.91 inches of rain fell throughout the month. The normal June precipitation in Seattle is 1.57 inches. However, through June 15th, Seattle has received 0.00 inches of rain. Little to no snowpack remains in the basin.
USACE typically maintains the water level between 20 and 22 feet as measured officially at the Chittenden Locks. Corps officials keep winter water levels at 20 feet, and begin the annual summer refill in February, targeting a 22-foot elevation by late May to early June. The higher level helps meet summer water use requirements, providing water necessary for fish passage, navigation, and salinity control. Water is slowly consumed throughout the summer, until it reaches the winter level typically in early December. During dry summers, it is possible for the water level to drop below 20.0 feet before steady rainfall returns.
Lake Washington was refilled earlier this year and reached 22.0 feet on May 18, 2025. The level began dropping due to normal operations on May 25, 2025.
The Corps has been conserving water by maximizing large lockage efficiency during the small-lock closure and construction work. This has included increasing the number of recreational vessels in each locking (which may include additional wait times, especially early in the morning or later evening). When the small lock construction work is completed, USACE officials will continue using both locks efficiently, which may include additional wait times, and prioritize use of the small locks. Operations to manage salinity and fish passage continue, with careful consideration and coordination to manage water usage.
As lake levels change, additional measures to conserve water could be implemented. USACE officials will continue to monitor lake levels and communicate with the public on additional conversation measures and anticipated lake levels.
The record low lake level is 18.35 feet, reached in 1958. The lowest recent recorded water level below 20 feet was 19.91 feet, measured in August 2015.
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