Potential Impacts of Climate Change and Increasing Human Water Demands on 
the Hydrology of Wisconsin Lakes
Timothy R. Asplund*, Wisconsin Department of Natural Resources, WI  

Recent drought conditions in Wisconsin, both in agricultural and forested regions, have 
caused some lakes to reach historic low water levels (Fig. 1 and 2). Water level fluctuations 
are normal for certain types of lakes, depending upon lake morphology, hydrology, climate, 
and geography. Indeed, water level fluctuations can be beneficial to healthy lake 
ecosystems; for example, encouraging emergent plant growth, compacting sediments, and 
deterring invasive species.  However, global climate change and increasing human 
demands for water may be altering these normal cycles, with implications for water quality 
and ecosystem services. Decreased water clarity, spread of native and invasive aquatic 
plants, loss of shoreline and littoral habitat, and increased human use of exposed lake beds 
are some of the potential consequences of extended periods of low lake levels.
Interestingly, Global Climate Models predict more rainfall and warmer temperatures for the 
Upper Midwest, which may produce contradictory effects: some lakes may rise due to 
higher groundwater recharge rates in the winter, while others may fall due to higher 
evapotranspiration rates in the summer. Land use patterns and groundwater pumping also 
interfere with the water cycle, increasing surface runoff and lowering water tables, with 
subsequent impacts to lake levels. Position in the landscape, catchment area, lake size and 
depth, and the relative proportion of groundwater inputs all influence the response of lakes 
to these competing factors. 
Using case studies from lakes in northwestern Wisconsin and the Central Sands, this 
presentation summarizes the many factors that influence lake levels in order to inform 
sound decision-making about water resource management and adaptation to global climate 
change in Wisconsin and the Upper Midwest.
*Presenter
Fig. 1 Anvil Lake (Vilas Co) Stage (1936 – 2006). Source: US Geological Survey









Fig. 2 Measured lake level elevations from 1959 to 2007 for 4 Waushara County lakes. 
Source: Waushara County Zoning Dept.


*Presenter