Bauer, a professor in the Department of Forest Resources, sits at his desk as his computer displays a satellite image of the Twin Cities, with dark splotches showing concentrations of impermeable surfaces like rooftops and pavement. These surfaces repel rain – and there lies the root of aserious environmental problem.
“More impervious surface means more runoff,” says Bauer. “When it rains, that water has to go somewhere. Pretty much all of the effects are going to be on the negative side.” The massive runoff brings a cascade of unintended consequences: water pollution, depletion of groundwater, flooding and harm to wildlife. According to the U.S. Environmental Protection Agency, urban runoff is the third-leading cause of freshwater pollution. This problem has profound implications for Minnesota, a land of 14,000 lakes, 92,000 miles of streams and rivers and one trillion gallons of groundwater.
Several professors from the College of Food, Agricultural and Natural Resource Sciences are grappling with the problem and helping devise solutions. Bruce C. Wilson, a storm water research scientist at the Minnesota Pollution Control Agency, says, “The University of Minnesota is one of the prime storm water research universities in the country.”
Urban development has substantially changed the natural flow of water. Originally, the land was covered in prairie, forests, savannahs and wetlands, and water slowly percolated through this giant filtration system.
In the 19th century, farmers installed drainage ditches and tiles to make fields suitable for planting. Then urban development covered the land with buildings, roads, sidewalks, parking lots and storm water systems – all designed to remove water as quickly as possible and channel it toward lakes and rivers.
More recently, researchers and regulatory agencies have become more sensitive to the consequences of these practices. “Over the past 10 or 15 years, there’s been agreement that the amount of impervious surface area is a good indicator of a lot of things related to environmental quality,” says Bauer.
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