Urban growth boundaries are created by governments in an effort to concentrate urban development — buildings, roads and the utilities that support them — within a defined area. These boundaries are intended to decrease negative impacts on people and the environment. However, according to a Penn State researcher, policies that aim to reduce urban sprawl may be increasing water pollution.
“What we were interested in was whether the combination of sprawl— or lack of sprawl — along with simultaneous agriculture development in suburban and rural areas could lead to increased water-quality damages,” said Douglas Wrenn, a co-funded faculty member in the Institutes of Energy and the Environment.
These water quality damages were due to pollution from nitrogen, phosphorus and sediment, three ingredients that in high quantities can cause numerous environmental problems in streams, rivers and bays. As a part of the EPA’s Clean Water Act (CWA), total maximum daily loads (TMDL) govern how much of these pollutants are allowed in a body of water while still meeting water-quality standards.
According to Wrenn, an associate professor in Penn State’s College of Agricultural Sciences, one of the reasons anti-sprawl policies can lead to more water pollution is because higher-density development has more impervious surfaces, such as concrete. These surfaces don’t absorb water but cause runoff. The water then flows into bodies of water, bringing sediment, nitrogen and phosphorus with it.
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Photo Credit: Ryan Hagerty via Wikimedia Commons
