WISCONSIN RESERVOIR REPORT

Last Updated: March 13, 2026

As of March 12, 2026, notable reservoirs and dams across Wisconsin are experiencing lower than average storage levels. Lake Winnebago, the state’s largest inland lake, recorded gage heights significantly below the average at both Oshkosh (1 ft compared to an average of 2.61 ft) and near Stockbridge (1 ft versus an average of 2.57 ft). Similarly, Lac Vieux Desert near Land O'Lakes, Devils Lake near Baraboo, Lake Mendota at Madison, Lake Monona at Madison, and Lake Waubesa at McFarland also show diminished gage heights, with reductions ranging from over a foot to as much as two feet below seasonal averages. These conditions suggest that the water bodies are experiencing lower water inputs, which could be a result of reduced snowpack levels, below-normal river inflows, or potentially increased water extraction.

The abnormalities in water levels at these important dams and lakes have various implications. For instance, Lake Winnebago serves as a critical resource for local communities, industry, and wildlife; thus, its low levels could affect water supply, recreational activities, and ecosystems. The lower-than-normal heights observed at Lac Vieux Desert could impact cross-state water management with Michigan, as it straddles the border. Meanwhile, the decreased gage heights for the Madison lakes – Mendota, Monona, and Waubesa – may influence urban water management, flood control efforts, and local fisheries. Without corresponding data on snowpack levels or river flows, it's difficult to pinpoint the precise cause; however, these deviations from the norm could potentially be linked to wider climatic patterns influencing precipitation and temperatures in the region. It is crucial for water resource managers and policymakers to monitor these trends closely and consider adaptive strategies to mitigate potential adverse impacts on the environment and water-dependent sectors.

Wisconsin has multiple reservoirs and dams that play a crucial role in providing water for irrigation, hydroelectric power generation, and recreational activities. The major reservoirs and dams in the state include Lake Winnebago, Lake Wisconsin, Castle Rock Lake, and Petenwell Lake. These reservoirs are fed by several rivers and creeks, such as the Wisconsin River, Fox River, Rock River, and Black River. The hydrology in the area is influenced by the snowpack in the northern mountains, particularly during the spring and summer months when snowmelt contributes to the streamflow. In recent years, Wisconsin has experienced both record high and low water levels due to changing climate patterns and extreme weather events. In 2021, drought conditions in the state led to lower than average water levels in some reservoirs and creeks. However, seasonal trends also play a role in water levels, with typically higher levels in the spring and early summer months. Overall, reservoirs and dams remain an important component of the state's water infrastructure, and their management is critical in ensuring sustainable water use and management.

Wisconsin has multiple reservoirs and dams that play a crucial role in providing water for irrigation, hydroelectric power generation, and recreational activities. The major reservoirs and dams in the state include Lake Winnebago, Lake Wisconsin, Castle Rock Lake, and Petenwell Lake. These reservoirs are fed by several rivers and creeks, such as the Wisconsin River, Fox River, Rock River, and Black River. The hydrology in the area is influenced by the snowpack in the northern mountains, particularly during the spring and summer months when snowmelt contributes to the streamflow.

In recent years, Wisconsin has experienced both record high and low water levels due to changing climate patterns and extreme weather events. In 2021, drought conditions in the state led to lower than average water levels in some reservoirs and creeks. However, seasonal trends also play a role in water levels, with typically higher levels in the spring and early summer months. Overall, reservoirs and dams remain an important component of the state's water infrastructure, and their management is critical in ensuring sustainable water use and management.