Winnebago pool lakes: Hydrology, water quality, and response to simulated changes in phosphorus loading

Science Center Objects

The Winnebago Pool Lakes are shallow, productive drainage lakes that have accumulated nutrients from its mixed agricultural/forest watershed and from the Fox River. High phosphorus concentrations often result in severe blue-green algae blooms that can produce harmful toxins. The USGS is evaluating the water quality and phosphorus budget of each lake and modeling eutrophication responses.

Aerial photo of Lake Winnebago and Lake Butte des Morts

Aerial photo of Lake Winnebago and Lake Butte des Morts.

The Winnebago Pool Lakes are shallow highly productive drainage lakes in northeastern Wisconsin. The lakes intercept the Fox River, and have accumulated nutrients from its mixed agricultural/forest watershed. As a result of the high nutrient loading and accumulated phosphorus in the sediments of the lakes, phosphorus concentrations in the lakes are high, which result in the lakes often experiencing severe blue-green algae bloom that may produce harmful toxins. Much of the nutrients and algae in Lake Winnebago are transported downstream to the Fox River, Green Bay, and ultimately the Great Lakes. The Fox River is one of the largest contributors of nutrients to the Great Lakes; approximately 50% of the nutrients that reach Green Bay originate from Lake Winnebago. Therefore, it is important to understand where the nutrients that enter the lakes originate, and how the lakes process the nutrients (lake response) in order to develop a TMDL for this system.



The objectives are to:

1.   Document the water quality of each of the Winnebago Pool Lakes;

2.   Determine a detailed phosphorus budgets for each of the Pool Lakes;

3.   Use calibrated eutrophication models to simulate the likely response of each of the Winnebago Pool Lakes to changes in phosphorus loading associated with various lake-management actions that might be implemented to improve water quality,

4.   Develop a better understanding of how management actions may affect the nutrient loading to the Lower Fox River and Green Bay;

5.   Provide information to construct a TMDL for the Winnebago Pool Lake, and information for the Lower Fox and Green Bay TMDL



This study consists of only one year of data collection followed by data analysis and report preparation. Detailed water and phosphorus budgets will be developed for the Pool Lakes by measuring all major inflow and outflow sources and estimating the magnitude of minor sources. Current water quality (trophic state) of each of the four Winnebago Pool Lakes will be obtained from the Wisconsin DNR and evaluated relative to longer-term trends and to measured phosphorus loading through the use eutrophication models in BATHTUB and the Jensen shallow-lake model. The euthrophication models will then be used to simulate the likely response of each of the Pool Lakes to phosphorus loading changes associated with various lake-management actions that might be implemented and specific climate scenarios. Output from the Lake Winnebago to the Lower Fox River will be estimated from data collected by the Wisconsin DNR at Neenah and Menasha. Information from this study will be supplied to those modeling the watershed downstream of Lake Winnebago and to those developing TMDL's for the system.


Publications and Reports

  1. Robertson, D.M. and Diebel, M.W., 2020. Importance of accurately quantifying internal phosphorus loading in developing phosphorus reduction strategies for a chain of shallow lakes. Lake and Reservoir Management.
  2. Robertson, D.M., Siebers, B., Diebel, M., and Somor, A., 2018, Response in the Water Quality of the Winnebago Pool Lakes, Wisconsin, to Changes in Phosphorus Loading, with Special Emphasis on the Effects of Internal Loading in a Chain of Shallow Lakes: U.S. Geological Survey Scientific Investigations Report 2018-5099, 58 p.,
  3. Wisconsin Department of Natural Resources. 2020. Upper Fox and Wolf Rivers TMDL.
  4. Wisconsin Department of Natural Resources, 2004, Water quality in the Lake Winnebago Pool: DNR publication number FH-229-04, 42 pages. Available at: