Study: How do we know if river restoration is working?
Streams and rivers around the world are in trouble -- more than a third of U.S. rivers are officially polluted or impaired. In hopes of reversing the damage, more than a billion dollars are now spent annually on river and stream restoration in the United States. And the number of restoration projects has increased by six-fold in the last decade.
But according to a major study to be published in the April 29 issue of Science, while river restoration has become a booming and profitable business, the United States does not have an adequate accounting system for the projects.
"Information as basic as what projects are being done where, who is doing them, and what the outcomes are is not available," said Margaret Palmer, the University of Maryland biology professor who co-authored the study.
"River restoration will play an increasingly prominent role in environmental management and policy decision," said Palmer, who has studied a number of stream and river projects in the Chesapeake Bay watershed. "Advancing the field requires rigorous analysis of restoration projects, and that requires basic information on the goals and outcomes"
To examine what is known about the results of river restoration efforts, Palmer and her postdoctoral associate, Emily Bernhardt, led an interdisciplinary team of scientists in compiling the first-ever comprehensive database of more than 37,000 U.S. stream and river restoration projects.
Their research endeavor, called the National River Restoration Science Synthesis, includes restoration projects from all 50 states, with special focus on seven geographic regions, including the Chesapeake Bay, the Pacific Northwest and the Sacramento-San Joaquin Valley.
They found that only 10 percent of all project records in their database included any kind of assessment. In the Chesapeake Bay region, which has more restoration per mile than any other area in the U.S. and is second only to the Pacific Northwest region in terms of total number, only six percent of the project records reported assessments.
"It's currently impossible to determine if the desired environmental benefits of river restoration are being achieved," said Bernhardt. It's time to start monitoring, the paper concludes.
"Monitoring isn't just about determining if a project is a success or failure," said Palmer. "It's about understanding what could be improved, so future projects can be better. River restoration has been an art, but it needs to be a science. To be a science means we must learn from what we do"
The most common reasons for river and stream restoration are to improve water quality, in-stream habitat, fish passage and bank stabilization. Larger, more expensive projects are more often aimed at reconnecting flood plains, modifying flows, recreation or aesthetic improvement and reconfiguring channels.
"It's time to agree on what constitutes successful river and stream restoration. The best projects help nature do the work by minimizing human intervention," Palmer said. "A project can have negative effects if not carefully designed."
In an April 18 paper in the British Journal of Applied Ecology, Palmer and the study group proposed standards for calling a restoration project successful. The proposal has been endorsed by an international group of scientists and a group of practitioners in the river restoration industry.
The five criteria for successful river and stream restoration offered by the Palmer-Bernhardt group are:
- Define a "guiding image" of the healthy river that could exist at a given site, so everyone understands what the desired goals are;
- Show measurable changes toward that image - such as larger fish populations or clearer water;
- Create ecological conditions that allow a river to be a more resilient, self-sustaining system -- this means that continuing efforts to fix the system are not necessary;
- Do no lasting harm -- the efforts to restore the system should not do more damage than good;
- Make the results of the project accessible to others.
"Standards are needed. Progress in the science and practice of river restoration has been hampered by the lack of agreed-upon criteria for judging ecological success," said Palmer. "It is critical that the broad restoration community, including funding agencies, practitioners and citizen groups, adopt criteria for defining and assessing ecological success in restoration."
For general information on the project and access to the newly released papers:
This article originally appeared in the 04/01/2005 issue of Environmental Protection.