According to a new study, stream restoration can filter pollutants out of local waterways, and improve the health of the Chesapeake Bay. However, Baltimore area residents where it would be most beneficial for water quality are less willing to pay for such projects. This is according to a University of Maryland environmental economist as well as an inter-disciplinary team of colleagues.
The team discovered that homeowners living in the wealthiest and densest areas of the study area were less willing pay to restore streams. In contrast, those living in densely populated areas were more likely to pay for restoration projects.
The study was published in the journal. Environmental Research LettersThis information should be used to inform water quality decision-makers, who often have to balance community support with environmental impacts.
“We see a strong urban to rural gradient where there’s a greater economic potential as far community support goes to stream restoration, but less ecological possibility to reduce nutrient contamination, and vice versa,” said David Newburn who is an associate professor in UMD’s Department of Agricultural and Resource Economics and co-author of this study. “The general trend is that stream restoration projects often involve a trade-off between the economic and environmental benefits. It’s not easy to find the win-win location.
While stream restoration projects can be tailored to the specific environment, they all aim at improving the ability of streams to absorb and process nutrients and preventing them from flowing downstream. These projects are crucial to improving water quality in the Chesapeake Bay as well as other watersheds around world. Stream restoration can alter the local landscape by removing trees or adding grassy meadows alongside streambanks.
Newburn and his colleagues sought to understand the complex relationship between stream restoration’s environmental benefits and homeowners’ perceptions of their value. Many homeowners pay for stream restoration through taxes and fees. The team combined the analysis of one the most extensive data sets on urban streamwater quality in the world with a homeowner survey, to estimate homeowners’ willingness to pay various restoration projects.
The researchers used long-term data from the Baltimore Ecosystem Study that has been collecting streamflow and nutrients since 1998. This data is a measure of ecological health in a waterway. It covers fully forested, highly developed, and agricultural watersheds. They used modern ecosystem modeling techniques and estimated how much nitrogen would have been removed by different stream restoration plans in a variety settings.
They concentrated on small, headwater streams in the Baltimore region that span urban, suburban, and exurban neighborhoods. This means neighborhoods outside of city sewer systems that are dominated primarily by single-family homes on one to five acres. Newburn and his collaborators developed hydrologic models that showed stream rehabilitation had the greatest nitrogen reduction in less densely populated areas. These areas are home to small streams with low flows. Streams with buffers made of grass had the highest nutrient levels, compared to streams that were lined with trees.
According to the researchers, these streams were able to process nutrients better because of the low water flow. Additionally, grassy buffers allowed for more sunlight to reach the water than trees covered stream banks. Sunlight is important because it helps algae in streams remove nitrogen from the water.
The areas with the highest nitrogen pollution reductions were those in Baltimore’s most densely populated urban areas. These neighborhoods are prone to flooding from rainstorms. The torrents of swift-moving waters and urban runoff from impervious surfaces such as parking lots and rooftops don’t allow streams to remove large amounts of the nutrient polluting material.
Next, researchers used homeowner survey data as a way to determine willingness to pay for stream restoration designs. Then they mapped their results across the study region.
Newburn stated that rural areas have a high environmental benefit. This is especially true if trees are removed and streambanks are mowed to allow sunlight to enter the streams. “But in rural areas, you get the lowest willingness or even resistance to tree removal from neighbors as compared with restoration elsewhere.
Trees are often a valuable amenity because homeowners enjoy their aesthetic benefits. Taking them down means that the neighborhood loses this value. However, in densely populated urban areas where streams are more likely be surrounded by man-made infrastructure, grassy meadows/trees can be added during restoration to provide green-space amenities that are often lacking, especially in lower-income urban communities.
Newburn pointed out that green space in urban areas can have social benefits that go beyond improving water quality. This could be considered when analyzing the socio-economic and environmental factors for decision makers. Newburn suggested that future research on the additional benefits of restoration projects, such as reducing urban heat island, restoring habitats and quality-of-life benefits, may uncover a greater balance that favors certain projects more than others.
*Andrew Rosenberg earned his Ph.D. in Agricultural Resource Economics at UMD and is now a Research Agricultural Economist at the USDA.
This research was supported by the National Science Foundation Coastal Science, Engineering and Education for Sustainability Program (Grant No. 1426819, and the National Science Foundation Long Term Ecological Research Program (Grant No. DEB-1027188), for the Baltimore Ecosystem Study, as well as the U.S. Department of Agriculture Economic Research Service. These organizations’ views may not be represented in this story.
