According to a new study by a University of Maryland environmental economist and an interdisciplinary team of colleagues, despite the fact that stream restoration filters pollutants out of local waterways and improves the health of the Chesapeake Bay, Baltimore area neighborhoods where it would have the greatest impact on water quality are far less willing to pay for such projects.
The researchers discovered that householders in the least densely inhabited and generally wealthier sections of their study region were less ready to pay for stream restoration projects, whereas those in the most densely populated areas, which tended to have lower-incomes, were more eager.
The findings of the study, which were published in the journal Environmental Research Letters, should aid decision-makers tasked with improving water quality, who must frequently balance community support with environmental consequences.
“We see this strong urban-to-rural gradient where in urban areas there’s a higher economic potential as far as community support to pay for stream restoration, but less ecological potential to reduce nutrient pollution, and vice versa,” said David Newburn, an associate professor in the Department of Agricultural and Resource Economics at UMD and co-author of the study. “The overall trend is that there’s often a trade-off for environmental and economic benefits from stream restoration projects, and it’s hard to find the win-win locations.”
Stream restoration projects vary significantly depending on the local environment, but they all aim to restore a stream’s ability to absorb and filter nutritional contaminants, preventing them from migrating downstream.
Water quality in the Chesapeake Bay and other watersheds throughout the world depends on programs like this. However, stream restoration can alter the surrounding landscape by removing trees and replacing them with grassy meadows along streambanks.
In rural areas you get this high environmental benefit, that has high potential to remove nitrogen pollution from waterways, particularly when you remove trees and have grassy streambanks to open up the streams to sunlight. But that’s where you get the lowest willingness to pay and sometimes even resistance to tree removal from nearby homeowners compared to doing restoration somewhere else.
David Newburn
Newburn and his colleagues sought to know more about the complicated relationship between stream restoration’s environmental advantages and the perceived value of homeowners who pay for it through taxes and fees.
To evaluate willingness to pay for various sorts of restoration projects, the team combined their analysis of one of the most complete data sets on urban stream water quality in the world with a homeowner survey.
The researchers used data from the Baltimore Ecosystem Study, which has been evaluating stream-flow and nutrient load (a measure of a waterway’s ecological health) across entirely forested, agricultural, and heavily developed watersheds since 1998. They calculated how much nitrogen will be eliminated by various stream restoration plans in various environments using modern ecosystem modeling tools.
They concentrated on small, headwater streams in Baltimore’s urban, suburban, and exurban communities, which are dominated by single-family homes on one to five-acre lots and are not served by city sewage systems.
Newburn and his colleagues used hydrologic models to show that stream restoration reduced nitrogen levels the most in less densely inhabited exurban areas, where little streams have modest flows. In comparison to tree-lined streams, streams with grassy buffers showed the greatest nutrient reduction.
Low water flow allowed the streams to digest nutrients in the water, while grassland buffers allowed more sunshine to reach the water than tree-covered stream banks, according to the researchers.
Sunlight is crucial because it aids algae in streams in more effectively removing nitrogen from the water. The improvements that reduced nitrogen pollution the least were in Baltimore’s most densely populated metropolitan districts.
During rainstorms, urban runoff from impermeable surfaces such as rooftops and parking lots causes local floods, and the torrents of fast-moving water do not allow streams to remove a significant percentage of the nutrient pollution.
The researchers next analyzed homeowner survey data to determine willingness to pay for various stream restoration plans and mapped their findings across the study area.
“In rural areas you get this high environmental benefit, that has high potential to remove nitrogen pollution from waterways, particularly when you remove trees and have grassy streambanks to open up the streams to sunlight,” Newburn said.
“But that’s where you get the lowest willingness to pay and sometimes even resistance to tree removal from nearby homeowners compared to doing restoration somewhere else.”
Trees are frequently seen as a valuable resource because homeowners appreciate their aesthetic benefits, and removing them devalues the neighborhood.
However, in densely populated metropolitan regions, where streams are more likely to be surrounded by man-made infrastructure, the restoration of grassy meadows or trees provides green-space amenities that are often lacking, particularly in lower-income urban communities.
Newburn pointed out that, in addition to improving water quality, more green space in cities provides social benefits that can be considered into decision-makers environmental and socio-economic analyses.
He also stated that future studies on additional restoration advantages such as reducing urban heat islands, restoring habitats, and improving quality of life may reveal a stronger balance favoring some projects over others.
Andrew Rosenberg earned his Ph.D. in Agricultural Resource Economics from the University of Maryland and now works for the USDA as a Research Agricultural Economist.
The Baltimore Ecosystem Study was funded by the National Science Foundation’s Coastal Science, Engineering, and Education for Sustainability Program (Grant No. 1426819), as well as the National Science Foundation’s Long-Term Ecological Research (LTER) Program (Grant No. DEB-1027188) and the U.S. Department of Agriculture’s Economic Research Service.
