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Effects of climate change in Wisconsin: Flooding in the south, drought in the north

Real Audio logoLISTEN (RealAudio file) as Madeline Gotkowitz of WGNHS and Tim Asplund of the DNR talk about the effect of droughts, floods, and lake levels on Wisconsin waters with Larry Meiller.

Recent weather patterns in Wisconsin have radically altered the landscape, although the type of change you see depends on where you are in the state. In northern or central Wisconsin, some lakes are drying up due to an extended drought. By contrast, heavy rains in southern Wisconsin have left people struggling to cope with floods, wet basements, and high lake levels.

Lake extremes are related to levels of both surface water and groundwater. Understanding the connections between weather patterns, hydrologic systems, and climate change is key to helping us anticipate and respond effectively. It’s also important to helping communities make informed decisions about remediation efforts.

Flooding in southern Wisconsin

groundwater flooding near Spring Green, farmhouse surrounded by water

Following intense rainfall in June 2008, much of southern Wisconsin was under water. In some areas, notably around Spring Green, floodwaters remained for months. Why so long? The water couldn’t drain because the underground water table was already at land surface. Before floodwaters could dissipate, the entire aquifer (the underground layer of rock that holds water) had to lower.
Groundwater flooding has become relatively common in southern Wisconsin over the past 2 years. The amount of rise in the water table depends on many factors, including the amount of precipitation, soil type, plant type, temperature, and porosity of the underlying aquifer. When the rising water table reaches the land surface, groundwater flooding occurs.

Groundwater flooding lasts much longer than flooding of streams or rivers. The water table may slowly decline as groundwater flows towards and discharges to nearby rivers and streams. Following the summer’s heavy rains, water levels in some wells in southern Wisconsin were nearly 10 feet above their historic highs.

Seepage lakes (lakes that have no streams flowing into or out of them) are also susceptible to groundwater flooding. When water table levels rise, so do lake levels, submerging beaches and flooding shoreline developments.

Read about groundwater flooding in Spring Green, Wisconsin: http://www.uwex.edu/wgnhs/news.htm

Community response to groundwater flooding

As the climate changes, groundwater flooding is likely to become more common than in the past. Builders and developers need to consider how high the water table may get when designing and locating buildings and highways. Subsurface structures (basements, septic systems, etc) need to be sited above the highest expected water table elevation. This might be many feet above the “average” water table. Hydrogeologic and hydrologic data provide information about how high the water table may rise.

Drought in northern Wisconsin

lake drying up in northern Wisconsin

Where southern Wisconsin has been hit by too much rain and snow, northern and central Wisconsin has been suffering from an extended drought. That part of the state has received significantly less precipitation than normal over the last 4 years, resulting in falling water levels. Some lakes are at their lowest level in 70 years.

Prolonged drought hurts boat access and compromises water quality. Lakes may also suffer fish kills.

For more details about the impact of falling water levels on northern lakes, read the Journal Sentinel’s May 23, 2009 article by Lee Bergquist: www.jsonline.com/news/wisconsin/45924602.html

More information

Wisconsin Department of Natural Resources lakes FAQ (dnr.wi.gov/lakes/commonquestions)
Questions and answers about Wisconsin lakes (low water levels, water quality, human health, and lake health)

University of Wisconsin–Extension Lakes Program (www.uwsp.edu/cnr/uwexlakes/)
Packed with information about lake ecology, lake organizations, programs, laws & grants, and more
PDF about low lake levels—www.uwsp.edu/cnr/uwexlakes/ecology/LowWater-Factsheet-color_small.pdf

Great Lakes Environmental Research Laboratory (www.glerl.noaa.gov/pubs/brochures/lakelevels/lakelevels.pdf)
2-page PDF explaining water level fluctuation on the Great Lakes; includes long-term lake level data

Sea Grant Institute—Climate change in the Great Lakes region (www.seagrant.wisc.edu/ClimateChange)
Includes a lengthy list of resources (readings, videos, web sites) with information about climate change in the Great Lakes Region

U.S. Drought Monitor (http://www.drought.unl.edu/dm/monitor.html)
A handy overview of drought "hot spots" throughout the country

USGS WaterWatch (waterwatch.usgs.gov/?m=real&w=gmap&regions=wi)
Current water resources conditions

USGS Wisconsin groundwater conditions (wi.water.usgs.gov/data/groundwater.html)
Includes current groundwater level data and links to conditions across the United States

Wisconsin Association of Lakes (wisconsinlakes.org)
Lake policy, publications, upcoming events, and information

Wisconsin Initiative on Climate Change Impact (wicci.wisc.edu/workinggroups/stormwater)
Addresses the problems communities face from increased rainfall and rising groundwater levels

Wisconsin State Climatology Office (www.aos.wisc.edu/~sco)


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