WASHINGTON RESERVOIR REPORT

Last Updated: December 5, 2025

In Washington, the latest observations of dam storage levels and water surface elevations indicate that several reservoirs are experiencing variances from their historical averages. Notably, Wynoochee Lake near Grisdale is at 768 feet, below its average of 776.35 feet, while Mud Mountain Lake near Buckley is also lower at 907 feet compared to its average of 930.2 feet. In contrast, Lake Shannon at Concrete is above its usual level, at 436 feet, exceeding the average of 420.47 feet. This suggests that particular regions are experiencing abnormal storage conditions that could be linked to recent weather patterns, including potential impacts from atmospheric rivers bringing prolonged rainfall to the West Coast. These conditions are verified by multiple sources reporting on regional weather and water monitoring data.

Among the reported abnormalities, Howard A Hanson Reservoir near Palmer shows a significant decrease in water level, standing at 1079 feet against an average of 1125.14 feet, indicating a potential concern for water supply in that area. Similarly, Baker Lake at Upper Baker Dam near Concrete is below average at 699 feet, with a typical level of 712.44 feet. On the other hand, Frankin Roosevelt Lake at Grand Coulee Dam is above average, measuring at 1284 feet versus the average of 1275.62 feet, which could be a response to regional precipitation events. These fluctuations might be related to changes in snowpack levels and river flows, with the recent drought summaries and weather outlooks hinting toward a shift in drought conditions and an increase in atmospheric river events that could affect water accumulation and distribution across these major dams and reservoirs.

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.