WASHINGTON RESERVOIR REPORT

Last Updated: December 19, 2025

In Washington, dam and reservoir levels are closely monitored due to their importance in flood control, water supply, and hydroelectric power generation. Recent observations have highlighted a mix of typical and atypical water surface elevations across the state's reservoirs. For example, Wynoochee Lake near Grisdale and Lake Tapps near Sumner are maintaining levels close to their historical averages, suggesting normal conditions. However, Mud Mountain Lake near Buckley and Howard A Hanson Reservoir near Palmer are currently recording water levels significantly above their averages, with Mud Mountain Lake notably 227.36 feet higher than its average. These anomalies could be indicative of recent heavy rainfall events or changes in water management practices.

Further analysis shows that abnormal conditions are present in several reservoirs, potentially linked to changing climatic patterns. For instance, Lake Shannon at Concrete is 19.49 feet above its average, possibly resulting from the region's strongest and more frequent atmospheric rivers, as reported by various sources including Oregon Public Broadcasting (OPB) and AOL.com. These atmospheric events, along with warmer fall temperatures, as stated by the Idaho Capital Sun, can lead to increased snowmelt and river flows, impacting reservoir levels. Franklin Roosevelt Lake at Grand Coulee Dam is also experiencing higher than average levels, which could be a response to strategic water management amidst regional discussions on water supply and climate adaptation, as highlighted by AOL.com and azcentral.com. Conversely, the negative value recorded for Lake Scanewa near Kosmos indicates a potential data error or an issue with the monitoring equipment that requires immediate attention to ensure accurate tracking and management of water resources. Cross-referencing these abnormalities with recent reports on atmospheric conditions and regional water management challenges provides context for understanding the current state of Washington's 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.