WASHINGTON RESERVOIR REPORT

Last Updated: December 18, 2025

Amidst a series of powerful storms and the warmest fall on record, Washington's major dams and reservoirs are showing varied responses in storage levels, as per the most recent observations. The Mud Mountain Lake, Howard A Hanson Reservoir, and Franklin Roosevelt Lake at Grand Coulee Dam are experiencing significantly higher water surface elevations compared to historical averages. In contrast, Wynoochee Lake near Grisdale and Moses Lake at Moses Lake are reporting levels below their typical averages. These abnormal conditions can largely be attributed to recent extreme weather patterns that have brought hurricane-force winds, heavy rain, and mountain snow, causing power outages and widespread environmental impacts. The high water levels could be a result of increased precipitation and runoff, while lower levels might reflect insufficient inflows due to variations in snowpack and river flows.

Specifically, the Mud Mountain Lake near Buckley has a current elevation at a notable 1159 feet, dwarfing its average of 930.6 feet. Similarly, the Howard A Hanson Reservoir near Palmer is also above its normal average, currently at 1158 feet compared to an average of 1125.18 feet. Meanwhile, Lake Shannon near Concrete has risen to 440 feet, well above its average of 420.51 feet. On the other end of the spectrum, Wynoochee Lake's level is at 774 feet, modestly below its average of 776.34 feet. Moses Lake's current elevation is at 1041 feet, which is also below the average of 1045.09 feet. These water surface elevations could be indicative of the recent weather turmoil's impact on the state's water storage infrastructure. The data suggests that while some reservoirs are coping with excess water, others are not receiving expected inflows. It is important to cross-reference these figures with multiple data sources to ensure accuracy and to monitor these reservoirs continuously, especially in light of changing weather patterns and potential flood risks.

Washington state has over 700 dams and reservoirs, many of which provide hydroelectric power and irrigation for agriculture. The Columbia River is the largest source of water for the state, with many major reservoirs located along its length. These include Grand Coulee, Banks Lake, and Lake Roosevelt. The Yakima River basin also has several important reservoirs, including Cle Elum Lake, Kachess Lake, and Bumping Lake. Snowpack in the Cascades and Olympics is critical for water supply, particularly for irrigation during the dry summer months. In recent years, drought conditions have affected much of the state, with record low snowpack levels in 2015 leading to restrictions on water use. Seasonal trends generally see peak water levels in the spring as snowmelt increases streamflow, followed by a gradual decline throughout the summer and fall. Overall, the hydrology of Washington is complex, with a mix of natural and human factors affecting the availability and use of water resources.

Washington state has over 700 dams and reservoirs, many of which provide hydroelectric power and irrigation for agriculture. The Columbia River is the largest source of water for the state, with many major reservoirs located along its length. These include Grand Coulee, Banks Lake, and Lake Roosevelt. The Yakima River basin also has several important reservoirs, including Cle Elum Lake, Kachess Lake, and Bumping Lake. Snowpack in the Cascades and Olympics is critical for water supply, particularly for irrigation during the dry summer months. In recent years, drought conditions have affected much of the state, with record low snowpack levels in 2015 leading to restrictions on water use. Seasonal trends generally see peak water levels in the spring as snowmelt increases streamflow, followed by a gradual decline throughout the summer and fall. Overall, the hydrology of Washington is complex, with a mix of natural and human factors affecting the availability and use of water resources.