Drawdown, Recovery, and Hydrostratigraphy in Wisconsin's Northeast Groundwater Management Area (Brown, Outagamie, and Calumet Counties)Julie C. Maas
There are two cones of depression in Wisconsin's Northeast Groundwater Management Area (GMA). The first major area of drawdown is in central Brown County, and the second is just east of Appleton near the Fox Cities communities of Little Chute, Kaukauna, and Kimberly. Between 2006 and 2007, eight communities in central Brown County stopped pumping groundwater for their municipal supplies and began using surface water instead, reducing daily withdrawals from the regional deep sandstone aquifer by approximately 12.25 million gallons. I studied the recovery of groundwater levels and estimated the volume of water that continues to be withdrawn from the regional aquifer in each pumping center.
In 2005, before any of the eight communities switched to surface water, the potentiometric surface of the deep aquifer was less than 300 feet above sea level in the central Brown County cone of depression. Between that time and mid 2009, groundwater levels recovered by more than 150 feet in some locations near the center of drawdown.
Current deep aquifer withdrawals in central Brown County are estimated to be 4.2 million gallons per day. In contrast, daily withdrawals from the pumping center around the Fox Cities cone have not changed considerably, and water levels in the Fox Cities do not seem to be affected by the reduced pumping in central Brown County.
This study involved developing a refined hydrostratigraphic model for the Northeast GMA. Recovery curves were analyzed in a regional aquifer test to describe spatial distribution of hydraulic conductivities of the deep aquifer and its confining unit. Geophysical logs and other hydrogeologic data obtained in the GMA allowed a better understanding of the properties of aquifer and confining units to be developed.Several policy implications and recommendations were outlined for responsible management of the groundwater resources in the Northeast GMA.