Monitoring and Predictive Modeling of Subdivision Impacts on Groundwater in Wisconsin

Population growth and urban expansion near many Wisconsin cities has resulted in residential development on agricultural land in rural areas. While developments closer to urban centers typically use city water and sewer services, rural developments usually rely on private wells and septic systems. Septic tank and leach field treatment of wastewater can release contaminants including a nitrate, bacteria, viruses, and household chemicals to the subsurface; at the same a time, rural residents depend upon groundwater for a clean, reliable drinking water source. In some areas, zoning ordinances discouraging unsewered residential development — or prohibiting them altogether — have been passed by a local officials concerned about groundwater quality. However, there is currently little information available about the long-term impact of unsewered residential use on groundwater quality and quantity.

Objectives: The goals of this project were to collect groundwater quality and water-level data at a developing subdivision near Madison, WI, and use the data to draw preliminary conclusions and construct predictive groundwater flow models to assess subdivision impacts.

Methods: This project required collecting water samples, analyzing water-level fluctuations and rainfall/runoff relationships, and developing computer models in order to identify the effects of subdivision development on groundwater quantity and quality and predict future impacts under different development scenarios.