It’s Arrested Urban Watershed Development

By Annie Zwerneman

They say April showers bring May flowers – but what happens to the rain that doesn’t end up watering plants?

In areas where the natural vegetation has been replaced by buildings, pavement, and other types of human development, a good deal of that rain water doesn’t get absorbed. Instead, it flows across the watershed, picking up pollutants and nutrients as it goes. In large urban areas, the natural systems can quickly become overwhelmed, leading to trouble in the form of impaired water bodies downstream, increased erosion, and damaged ecosystems.

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EPA interns sampling a stream near Providence, RI.

EPA scientists helped address the growing concern for these pollutants by testing the waters in streams throughout the northeastern United States. A team of EPA researchers, led by Nathan Smucker and Anne Kuhn, set out to understand how we can better manage pollution that negatively affects valuable freshwater resources.

Smucker, Kuhn, and their team selected sites to research that were evenly distributed throughout the heavily urbanized Narragansett Bay watershed. Specific sites were picked in order to capture a complete range of low to high development in watersheds that drain to the bay.

The science team focused on how important components of stream food webs and water quality were affected by urbanization. In conjunction with other EPA research in the region, they found that riparian vegetation was integral to reducing negative impacts on algae and macroinvertebrates associated with watershed development. Stream ecosystems and food chains are further impacted when riparian vegetation is destroyed by development or erosion. Their research showed that if vegetation buffers are maintained next to streams, some of the negative effects of watershed development can be reduced.

Results from the research and literature review analysis will provide insight into preventative actions for decision makers that are building or developing on watersheds and aid with managing stream resources in watersheds with existing development. By identifying how past development has affected stream ecosystems, we can predict what might happen as ongoing development occurs, and we can work proactively on strategies to keep ecosystems intact and pollution at bay.

About the Author: Annie Zwerneman is an intern for the EPA’s Office of Research and Development.

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