WASHINGTON RESERVOIR REPORT

Last Updated: December 22, 2025

Washington's dams and reservoirs are essential to the state's water management, but recent observations indicate varying conditions across these critical water bodies. As of December 22, 2025, Mud Mountain Lake near Buckley is notably higher than average, with a current elevation of 1148 feet, significantly above its average of 930.76 feet. This anomaly is in stark contrast to Baker Lake at Upper Baker Dam near Concrete, which shows a lower than average elevation (705 feet compared to the average of 712.42 feet). These disparities in reservoir levels may be related to regional climate phenomena, including snowpack and river flows, which have been influenced by broader meteorological events.

In-depth analysis reveals that while Lake Tapps near Sumner and Diablo Reservoir near Newhalem are relatively stable at 539 and 1201 feet respectively, very close to their average levels, Lake Shannon at Concrete is experiencing higher than average water surface elevation (437 feet against an average of 420.52 feet). Franklin Roosevelt Lake at Grand Coulee Dam is also slightly above its typical level, at 1284 feet. This follows a trend where some areas are seeing elevated water levels, possibly as a result of heavy rainfall and an atmospheric river event that brought significant precipitation to the Pacific Northwest. Conversely, the data for Lake Scenewa near Kosmos is currently unavailable, marked by an erroneous value, thus complicating the assessment for that reservoir. Cross-referencing with sources indicating an increased occurrence of extreme weather events, such as flash flooding and variations in snowpack levels, suggests that anomalies in dam and reservoir conditions could be attributed to such climatic disruptions, impacting water storage and flow patterns. It is critical for stakeholders to monitor these conditions continuously, as they have direct implications on water availability, flood management, and ecosystem health in Washington state.

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.