WASHINGTON RESERVOIR REPORT

Last Updated: February 17, 2026

Washington's network of dams and reservoirs is experiencing a range of conditions as the latest observations indicate some deviations from average storage levels. These changes are likely influenced by prevailing weather patterns including a mix of drought and atypical winter warmth. Notably, the Mud Mountain Lake near Buckley is recording a water surface elevation of 904 feet, significantly lower than its average of 931.42 feet, while Franklin Roosevelt Lake at Grand Coulee Dam is higher at 1284 feet compared to its 1275.62 feet average. These phenomena could be related to the varying impacts of climate conditions such as the snow drought in the Pacific Northwest, which may contribute to alterations in river flows and snowpack levels affecting reservoir storage.

Among the major dams, Wynoochee Lake near Grisdale and Lake Shannon at Concrete are showing lower than their average elevations, which might be attributed to the region's dry conditions. In contrast, South Fork Tolt Reservoir near Carnation is slightly above its average, indicating a possible accumulation of runoff or regulated discharge management. Reports such as 'From December floods to February sunshine: Washington’s winter whiplash' and discussions of 'unprecedented snow drought' in parts of the Pacific Northwest suggest that water storage levels in Washington state are being affected by unusual weather patterns, which could have implications for water supply and management. On the other hand, notable data outliers like Lake Scanewa and Castle Lake near Mount St Helens report unreliable measurements, indicating potential issues with data collection or transmission. Understanding these variations and their potential causes is essential for managing water resources effectively, especially in light of the broader weather-related challenges highlighted by numerous sources, including potential flooding events and concerns about wildfires and water shortages.

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.