Groundwater-Lake Interaction: Response to Climate Change in Vilas County, Wisconsin

Background/Need: There are numerous lakes and wetlands in Wisconsin and most have some connection with the groundwater system. Groundwater fluxes, while difficult to measure, may be important to the hydrology and chemistry of lakes. Stresses on the groundwater system and changes in groundwater fluxes affect surface water levels, which in turn affect groundwater levels in a dynamic feedback process. Problems in Wisconsin that critically depend on recognition and quantification of this feedback mechanism include predicting the effects of land use and proposed mining operations on groundwater and lake levels, urbanization on groundwater/surface water systems, agricultural drainage systems on wetlands, and potential global climate change on hydrologic systems.

Standard groundwater models assume that surface water levels are known inputs, and therefore do not recognize the true nature of the connection between surface water and groundwater. Recognition of the need for improvement in the way in which groundwater models handle surface water inputs led to development of specialized software packages for MODFLOW (the industry’s standard code for groundwater flow modeling) that address the dynamic exchange of groundwater with rivers and reservoirs. Watersheds containing important lake and stream systems require models that include consideration of the dynamic exchange of waters among groundwater, lakes and streams.

The Trout Lake Basin study site is ideal for addressing issues related to groundwater-surface water interaction inasmuch as long-standing and on-going hydrological research with accompanying data collection and monitoring occurs at this site through the National Science Foundation’s Long Term Ecological Research (LTER) program and the U.S. Geological Survey’s Water, Energy, Biogeochemical Budgets (WEBB) program.

Objectives: (1) to determine effects on water levels of potential climate change in the Trout Lake Basin, Vilas County, Wisconsin and (2) to define the contributing groundwater basins and travel times to lakes within the Trout Lake Basin.