Karst: Topography Not Suited for a CAFO

Karst topography is a landscape shaped by dissolving layers of bedrock such as the soluble limestone found in southwestern Wisconsin; this area is called the Driftless Region, meaning unglaciated, with high ridges and deep, narrow valleys or coulees. Karst topography is found throughout the Driftless Region and some primary characteristics include sinkholes and caves. Think Swiss cheese! Its nature is cavernous, both large and small, and therefore highly permeable, resulting in reduced opportunities for contaminants to be filtered out.

With the completion of a multiple-year northeastern Wisconsin karst study conducted by scientists from Discovery Farms and a respected hydro geologist from UW Oshkosh, a good understanding emerges of possible environmental threats facing individuals living in karst regions in Wisconsin. This research concludes that even with farm operations following certified manure application plans, a higher risk for ground water contamination exists. Clearly, underlying fractured bedrock common with karst geology was the most significant factor influencing this threat.

Data collected in the field verified a rapid movement of water and nutrients through this karst bedrock layer. Recommendations from Discovery Farm scientists included a system of rating the risk for contamination based on overlays of soil depth and the composition of the underlying karst bedrock. It is likely that without identifying areas of risk and making adequate adjustments to surface stored or applied wastes, ground and surface water contamination is probable. It could be argued that siting of surface waste storage sites (landfills) should also consider this increased risk. Even with present liner technology designed to provide an "impervious barrier" on the landscape surface, an ever changing bedrock layer presents an imminent threat of failure for these system designs. Regional topography represented by steep hills and deep valleys also presents a greater threat to surface waters due to rapid drainage after rain events.

Although the data and conclusions of the northeast study are not directly transferable to southwest Wisconsin, we predict very similar recommendations would be the result of good scientific research. Precautionary measures in land management are vital for protecting our precious ground and surface waters. A separate research study of southwest Wisconsin geological conditions is being considered for the near future. Goals for supporting a regional karst study would be to create scientifically defensible regulations while keeping in mind the need to address varied interests of stakeholders living in the region.

All government representatives, utilities, and businesses seeking to apply or store waste products on the landscape have an enormous responsibility. As stewards of the valuable natural resources entrusted to us, it is important that we hold our neighbors, regulatory agencies, and government representatives accountable for protecting our health and environment.

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