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In areas where the natural vegetation has been replaced by buildings, pavement, and other types of human development, a good deal of that rain water doesn’t get absorbed.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.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.

Studying Stream Restoration

By Marguerite Huber

Stream running through a lush, forested landscape

Forested stream

When I was younger, there was a prairie and stream behind my house. I ran and played there all the time with my friends until a house was built in its place. The lot was transformed from a wild, overgrown landscape to a manicured lawn. With the prairie gone and stream no longer enticing our adventures, we stopped playing there.

When homes and roads are built, they affect the habitat, quantity, and quality of water in downstream ecosystems (as well as natural places for kids to play!). Additionally, it causes an increase in nutrients like the fertilizer from that manicured lawn, and sediments, metals, and other pollutants making development a leading factor in stream impairment.

Local communities are increasingly turning to engineered techniques intended to reduce or eliminate the impacts of development on streams and other aquatic ecosystems. But do such efforts work?

Stream running through an urban area

Urban stream

EPA scientists Naomi Detenbeck and Nathan Smucker set out to evaluate how well “out-of-stream” restoration actions (those actions that take place in the watershed as opposed to within streams) work and to identify any general trends found in the scientific literature. They examined the response of water quality, habitat and hydrology, and ecological structure and function to development and restoration.

The scientists used statistical analysis to identify more than 40-years’ worth of published scientific literature on effective ways to protect streams from the unintended impacts of activities that harm streams. Starting with more than 1,400 papers, they pared it down to thirty-eight that covered forty-four restoration projects.

Smucker and Detenbeck found that the projects covered a number of stream restoration actions such as riparian buffers, human-made wetlands, and stormwater ponds. The projects looked at the bigger picture of managing streams by focusing on their watersheds. These “out-of-stream” approaches are important because efforts that have focused solely on habitat restoration within streams have had limited success.

Pooling together data from all the papers, the researchers found that biodiversity was reduced by more than half in unrestored urban streams and measures of things such as reducing erosion, nitrogen fixation, and other ecosystems services were significantly greater in restored streams than unrestored.

Even if it is impossible to fully restore streams, preventative actions can still be taken to protect downstream ecosystems in watersheds that are facing future development. In addition, tracking restoration projects (like the ones used in the studies) and ongoing monitoring would benefit future efforts to protect, restore, and manage streams.

Knowing what works and what doesn’t can help government agencies, policymakers, and citizens recognize and evaluate potential environmental outcomes resulting from their actions and decisions. It can also aid in setting restoration goals, prioritizing sites to monitor, and guiding future decisions and development as populations continue to grow.

About the Author: Marguerite Huber is a student contractor with EPA’s Science Communications Team.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.