There are greater environmental benefits for homeowners who are willing to pay less

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 in the wealthiest areas of their study were less willing and able to pay to restore streams. However, those living in the most densely populated areas with lower incomes were more willing to fund 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 in urban areas, there’s a higher potential for community support to pay stream restoration, but lower ecological potential to reduce nutrient polluting, and vice versa,” said David Newburn (associate professor in the Department of Agricultural and Resource Economics, UMD). The overall trend is that stream restoration projects often result in a trade-off between economic and environmental benefits. It’s difficult to find win-win locations.

While stream restoration projects can be tailored to the specific environment, they all aim at improving the stream’s ability and processing of nutrient pollutants. They also prevent them from flowing downstream. These projects are essential to improving water quality at the Chesapeake Bay, and other watersheds worldwide. However, stream restoration can also change the landscape by removing trees and adding grassy meadows to 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 of most comprehensive data sets about urban stream water quality with a survey of homeowners to determine the homeowner’s willingness to pay various restoration projects.

The researchers used long-term sampling data from Baltimore Ecosystem Study to determine streamflow and nutrient loads (a measure of ecological well-being of a waterway). This study has been monitoring streamflow across fully forested, agricultural, and highly developed watersheds since 1998. They used modern ecosystem modeling techniques to estimate how much nitrogen would be removed by stream restoration designs in different settings.

They focused on small, headwater stream in the Baltimore region. This included neighborhoods that lie outside of city septic systems and are dominated by single-family homes with one to five acres lots. Newburn and his associates created hydrologic models showing stream restoration was most effective in areas with less densely populated populations. Small streams have low flows, so Newburn and colleagues developed hydrologic modeling. Streams with grassy buffers had higher nutrient reductions than streams lined with trees.

Researchers believe that these areas had low water flow, which allowed streams to process nutrients in the water. Grassy buffers allowed more sunlight into the water than tree-covered stream banks. Sunlight is important because sunlight helps stream algae remove nitrogen more effectively.

The most densely populated areas of Baltimore City had the lowest levels of nitrogen pollution reduction. These areas are where urban runoff from impervious surfaces, such as rooftops and parking lots, can lead to flooding during rainstorms. Furthermore, the torrents that swiftly moving water don’t allow streams the time to remove a significant amount of the nutrient contamination.

Next, researchers used homeowner survey data as a way to determine willingness to pay for stream restoration designs. Then they mapped their results throughout their study region.

Newburn stated, “In rural areas, you get this high level of environmental benefit, that has the high potential to remove nitrogen from waterways, especially when you remove trees and have streambanks of grass to open up the streams for sunlight.” “But, this is where you get the lowest willingness and sometimes even resistance to tree-removal from nearby homeowners as compared to restoration done elsewhere.”

Trees are often a valuable amenity because homeowners enjoy their aesthetic benefits. Taking them down means that the neighborhood loses this value. In densely populated urban areas where streams are more likely be surrounded by manmade infrastructure, grassy meadows, or trees, during restoration provide green-space amenities that are often lacking, especially in lower-income urban communities.

Newburn stated that urban green space has many social benefits, beyond water quality improvement. These can be considered in the socio-economic and environmental analysis that decision makers will need to make. 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.

The paper “Spatial Asynchrony and Environmental and Economic Benefits from Stream Restoration” by Ruoyu Zhang (Ruoyu Zhang), David Newburn, Andrew Rosenberg. Jonathan Duncan, Lawrence Band. Environmental Research Letters.