WISCONSIN RESERVOIR REPORT

Last Updated: December 21, 2025

In Wisconsin, the latest observations indicate that several dams and reservoirs are experiencing slightly lower than average storage levels. Notably, Lake Winnebago at Oshkosh and near Stockbridge, as well as Lac Vieux Desert near Land O'Lakes, Devils Lake near Baraboo, Lake Mendota at Madison, Lake Monona at Madison, and Lake Waubesa at McFarland, are all reporting gage heights below their respective averages as of December 21, 2025. These measurements suggest that the water bodies are currently experiencing reduced inflows or higher than average outflows. To a layperson, this means that the water levels in these reservoirs are lower than what is typically expected for this time of the year, which could impact water supply and recreational activities.

The deviations from average gage heights range from approximately 0.57 to 1.94 feet below normal. Lake Winnebago, a pivotal water body in the state, shows a current gage height of 2 feet at both Oshkosh and Stockbridge, against an average of around 2.6 feet. Devils Lake is currently at 7 feet, significantly lower than its average of 8.13 feet. Similarly, the Madison chain of lakes including Mendota, Monona, and Waubesa are all showing lower levels than average, which may be a concern for local ecosystems and water management. These abnormal conditions could possibly be attributed to factors such as lower snowpack levels leading to reduced spring runoff, below-average precipitation, or potentially increased water usage. Without additional data on weather patterns, river flows, or human activities, the precise cause of the reduced gage heights remains speculative. However, these conditions warrant monitoring as they can have implications for water availability and the management of these critical water resources.

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.