Researchers Ask: “How Effective Are Stream Restoration Projects?”

A lengthy Bay Journal article (2016-10-23) examined ongoing efforts to determine exactly how effective stream restoration projects are at improving water quality and impaired waterways. Stream The article stated that the Chesapeake Bay Trust has awarded 9 research grants since last year to examine the effect of stream restoration projects on both water quality and habitat.

“When questions are raised, we can’t ignore them,” said Jana Davis, the Trust’s executive director. “We have to address them.” While every restoration project is at least slightly different, Davis said, “Hopefully there are some trends. Once we find out what that trend is, we can apply it more widely.”

There’s a lot at stake. A total of 300 miles of stream reaches have already undergone restoration across the six-state watershed, according to Bay Program data. Another 440 miles are targeted for overhauls by 2025. With construction costs on urban stream restorations averaging more than $600 per foot, hundreds of millions have been spent to date, and the final tally seems sure to top $1 billion. …

Restoration advocates say re-engineering stream channels can help mimic the functions once provided by expansive flood plains, reducing bank erosion and cutting down on a major source of water-clouding sediment to the Bay. The practices can also curb the flow of phosphorus and nitrogen, the two nutrients that feed the Bay’s algae blooms and its fish-stressing “dead zones,” proponents say.

But some scientists say many stream restoration techniques don’t work equally well everywhere, that some projects have only limited environmental benefits, and that there’s not been enough long-term monitoring to tell if the upgrades hold up over time.

The article noted that many stakeholders support increased monitoring and scientific review of stream restoration techniques:

“I’m glad there’s actually some science” looking at it, said Tom Schueler, executive director of the Chesapeake Stormwater Network, a Maryland-based nonprofit. Schueler co-chaired a panel of experts tasked by the Bay Program with quantifying how much credit to give stream restoration projects for reducing sediment and nutrient pollution to the Bay and its tributaries. …

“If we don’t do the right kind of monitoring, the steam restoration industry is headed for a huge backlash when (people) realize how much money is being spent on it,” said Jim Gracie, president of Brightwater Inc., an environmental consulting firm that’s been doing restoration work for three decades.

Erik Michelsen, head of watershed protection and restoration for Anne Arundel County, said local officials like him need more information as they plan more and more of these projects. Arundel does more than most — it projects spending roughly $175 million over the next four years on stream restoration.

“There’s a lot of money being spent on monitoring,” Michelsen said, “to check the box on various permit requirements. But there’s almost a consensus that a lot of the money being spent on that is not well-spent and not being used to collect data that’s necessarily comparable or (collected) in a scientifically meaningful way.” Now, he said, more people are asking, “Is there a way to spend the same amount of money and get better results?”

The article also described the monitoring projects undertaken by the Smithsonian Environmental Research Center for the Muddy Creek and Church Creek restoration projects in Anne Arundel County. A key challenge with stream restoration techniques is to get a better idea of how much runoff and nutrients they actually reduce – so they can accurately be credited under the Chesapeake Bay and local Total Maximum Daily Load (TMDL) requirements. The article noted the mixed findings of the Smithsonian and other researchers:

Solange Filoso, a biogeochemist with the University of Maryland Center for Environmental Science, is reviewing all of the stream restoration projects she’s studied for the last nine years “to really try to determine once and for all what kind of designs are more effective and at what position in the watershed restoration performs better.”

She’s still pulling all of the data together, she said, but as with the real estate business, location appears to matter in planning a restoration project. Those carried out farther up in a watershed appear to be more successful than those done farther downstream, she said. And conversely, if runoff surges upstream are not tempered somehow, they can dump sediment that smothers restored reaches downstream. …

Michael Williams, a research associate at the Smithsonian Environmental Research Center, said he’s seen cases where completed restoration projects were removing sediment and nutrients, but were undermined by a big storm or a new development that increased runoff from the watershed. …

Filoso said her research has found that nitrogen and even phosphorus removal varies considerably in restored stream reaches. In one project she studied, the nitrogen in the water was chemically transformed from one type to another, but not really removed. And in some cases, she’s also seen evidence that restoration may capture sediment, but actually boost the amount of chemically reactive phosphorus in the stream.

“So this idea of ‘restoring is better than nothing,’ I’m not sure,” she said.

The article concluded by noting that while stream restoration projects can produce positive results, it is important to carefully define what you view as a successful outcome and that a more holistic approach may be needed – with a variety of water quality and habitat restoration techniques utilized in order to fully restore a stream and its ecosystems.

Useful Links

Prior Conduit Street Coverage of Stream Restoration