A half-century of scientific work has predicted or observed that high capacity well pumping in the Wisconsin Central Sands lowers water levels in the aquifer, lakes, and wetlands as well as the flows of streams. Other such work provides a framework for understanding Central Sands geology and surface water / groundwater connections. Just a sampling includes the USGS study of the Little Plover River (Weeks and others 1965), the USGS study of the greater Central Sands by Weeks and Stangland (1971), various works by Kraft and others (2010, 2012, 2014, 2016), a review by Kniffen and others (2014), and a soon to be released WGNHS / USGS re-study and advanced modeling of the Little Plover River (Bradbury and others). The work specific to the Central Sands builds on two centuries (or more) of basic science that explored groundwater, surface water, and pumping connections.
Yet many are unaware of how groundwater and surface water are connected, and believe groundwater pumped from wells magically comes from … well, they’re not sure.
Rather than recapitulate a long scientific history (that has been done elsewhere), let me try here to present a common-sense line of evidence that groundwater pumping is drying Central Wisconsin lakes and streams. The logic train goes like this:
- Water has declined in parts of the central sands where irrigation predominates …
- … but water has remained normal or high in areas with fewer irrigation wells.
- Purported causes other than pumping are unable to explain why levels in heavily irrigated areas are low while levels in less irrigated areas are high.
Irrigation pumping easily explains the observed declines in irrigated areas and normal-to-highs in non-irrigated areas.
1. Water has declined in parts of the central sands where irrigation predominates…
Water conditions of lakes, wetlands, streams, and groundwater have been extraordinarily low in parts of central Wisconsin where large numbers of high capacity irrigation wells dominate the landscape. This “low-ness” is evident from long term records and observational data. For instance, recent flows in the Little Plover were below its 1959-1987 historic low, a period that contained disastrously dry years. The Plover monitoring well, with a record of almost 60 years, has declined beneath lows previously associated only with extreme drought. Lakes associated with large numbers of irrigation wells show declines.
Even where water level or flow data do not exist, observations reveal declining water levels. For instance, beaches are wider than the historic norm and boat landings no longer reach the water, even during years that are wet.
2. … but water has remained normal or high in areas with fewer irrigation wells
Outside heavily pumped areas, water levels dipped during a modest dry period of 2007-2009, (but not below levels of historic drought), and then rebounded because of wet weather and were high in 2016. Contrast the record of the Nelsonville monitoring well (below) with the Plover well (above) or Sunset Lake with Wolf Lake.
3. Purported causes other than pumping are unable to explain why levels in heavily irrigated areas are low while levels in less irrigated areas are high.
Numerous hypotheses as to what might be causing water levels to decline besides irrigation pumping have been advanced and falsified. “Record drought” is the most popular. But precipitation records do not bear out a drought claim: the region was in prolonged moisture stress from 1946-1964, when precipitation was 2.1-2.7 inches per year below normal in central Wisconsin. This is also the period when water levels and streamflows exhibited record lows in areas with few high capacity wells. Precipitation has increased since then, coinciding with a rebound in levels and flows, and since the year 2000 annual precipitation amounts have been 1.4 to 1.9 inches above average.
Some have stated that stressed lakes and streams are the result of climate change. Climate has indeed changed: it’s become wetter! Climate change is completely unable to explain why levels and flows only decline in more heavily irrigated but not less irrigated areas.
Cited by some is a correlation of impacted central sands water levels to the Great Lakes and drought-stricken parts of northern Wisconsin. These correlations are spurious and cannot explain why depleted water conditions occur in areas with many irrigation wells but not those in areas with few irrigation wells.
“Trees are drying lakes and streams!” has been invoked by some, but this cannot explain why lakes and streams are drying in areas with much irrigation and little forest cover, while in places with little irrigation and much forest water levels are “normal” or high.
4. Irrigation pumping easily explains why lower water levels occur in highly irrigated areas while normal to high levels occur in less irrigated areas.
Groundwater flow modeling in the central sands and water level comparisons (Kraft et al. 2012; Bradbury et al. in press) show a good match between drawdowns in highly irrigated areas and well-vetted estimates of consumed irrigation water (evapotranspiration increase and net recharge decrease) on irrigated lands (Weeks and Stangland 1970; Naber 2011). No other purported explanation does.
Cited Literature and Other References
Bradbury, K.R., M. Kniffen, J. Krause, M Fienen, S. Westenbroek, A. Leaf, P. Barlow. In press. A groundwater flow model for the Little Plover River Basin in Wisconsin’s Central Sand Plain. Wisconsin Geological and Natura History Survey and United States Geological Survey.
Clancy, K., G.J. Kraft, and D.J. Mechenich. 2009. Knowledge Development for Groundwater Withdrawal Management around the Little Plover River, Portage County Wisconsin. Center for Watershed Science and Education, University of Wisconsin, Stevens Point, WI.
Kniffen, M., K. Potter, A.J. Bussan, J. Colquhuon, K. Bradbury. 2014. Sustaining central sands water resources. University of Wisconsin – Extension. https://learningstore.uwex.edu/Assets/pdfs/G4058.pdfthttps://learningstore.uwex.edu/Assets/pdfs/G4058.pdfps://learningstore.uwex.edu/Assets/pdfs/G4058.pdf
Kraft, G.J., D.J. Mechenich, K. Clancy, and J. Haucke. 2010. Groundwater Pumping Effects on Groundwater Levels, Lake Levels, and Streamflows in the Wisconsin Central Sands. Center for Watershed Science and Education, University of Wisconsin, Stevens Point, WI.
Kraft, G.J., D.J. Mechenich, and J. Haucke. 2012a. Information Support for Groundwater Management in the Wisconsin Central Sands, 2009 – 2011. Center for Watershed Science and Education, University of Wisconsin, Stevens Point, WI.
Kraft, G.J., K. Clancy, D.J. Mechenich, and J. Haucke. 2012b. Irrigation Effects in the Northern Lake States: Wisconsin Central Sands Revisited. Ground Water Journal. V. 50 (2): 308-318.
Naber, M.R. 2011. One-dimensional soil-plant-atmosphere modeling of the Wisconsin Central Sand Plain to estimate evapotranspiration and groundwater recharge under different vegetation types. M.S. Thesis, University of Wisconsin – Madison.
Weeks, E.P., and H.G. Stangland. 1971. Effects of irrigation on streamflow in the Central Sand Plain of Wisconsin. U.S. Geological Survey Open-File Report. Reston, Virginia: USGS. http://wi.water.usgs.gov/pubs/OFR-sandplain/index.html
Weeks, E.P., D.W. Ericson, and C.L.R. Holt, Jr. 1965. Hydrology of the Little Plover River basin Portage County, Wisconsin, and the effects of water resource development. US Geological Survey Water-Supply Paper 1811. United States Government Printing Office, Washington, DC.