Whitemarsh Run looks a mess, more a construction site than a stream.
With its flow temporarily dammed and diverted, a track hoe is carving out a new, more sinuous channel for the badly degraded waterway running through a built-up patch of northeastern Baltimore County. New banks are being built, armored in places with granite boulders — all part of a $13 million makeover that's intended to help clean up the nearby Bird River and the Chesapeake Bay.
Bits of the 11/2- mile long project that have been completed look like a tranquil country stream, its water sliding across stones placed along and in its channel. But some scientists and environmentalists question whether such feats of ecological engineering, by themselves, can really revive a dead stream, or even reduce pollution much.
"I can build a wiggly stream," said Martin W. Doyle, a professor of river science and policy at Duke University who's studied and worked on restoration projects. "All over Baltimore County, all over North Carolina, there's lots of wiggly streams that don't do jack."
The debate over the merits of stream restoration has taken on significance as such projects have become a favored tool of local governments in the Baltimore area as they work to meet tough federal mandates to reduce sediment and nutrient pollution fouling the bay and its tributaries.
Nearly 3,700 miles of streams across Maryland are targeted for restoration work by 2025, nearly all of them in urban areas, according to a panel of experts who studied the issue. Baltimore County expects to spend about $13 million a year on restoration projects, according to Vincent J. Gardina, the county's director of environmental protection and sustainability.
Much of the money for projects in Baltimore County and other large jurisdictions comes from stormwater remediation fees paid by property owners — fees that have become political fodder and derided by some as the "rain tax." The fees are mandated by the state for Maryland's 10 most populous jurisdictions.
County officials counter critics of such efforts, saying they've been doing it for 25 years and have had some of their 65 projects to date held up as models by state and federal environmental agencies.
"We are nationally recognized leaders in stream restoration," said Robert R. Ryan, the county's watershed restoration manager.
Urban and suburban streams often suffer severe erosion as the land that drains into them becomes covered with pavement and buildings. Rainfall that used to soak into the ground runs to the stream, where even a modest downpour can turn a quiet stream into a raging flood.
Proponents say restoration efforts reduce stream bank erosion, which studies show is the major source of sediment pollution in the bay and its tributaries.
Restoration also curbs nutrient pollution that feeds the bay's algae blooms and its "dead zone," proponents say. Phosphorus, one of the problem nutrients, typically clings to soil particles — so when erosion is curtailed, there's less phosphorus getting into the water.
But some scientists say controlling erosion is only one facet of restoring a waterway. They say its benefits don't last if nothing else is done to reduce runoff from development before it pours into the stream.
"You can't ask a stream to do everything an entire watershed should do," said Margaret A. Palmer, a University of Maryland scientist who's researched restoration ecology. She's published studies finding "no consistent evidence" that restored streams reduce nitrogen, another key pollutant fouling the bay.
And while stabilizing stream channels may reduce erosion at first, she said, the benefit is likely to decrease over time.
"Show me that the water quality is better after restoration than before," agreed Doyle, who's also published research questioning the ecological benefits of restoration. "In the vast majority of cases, the data do not exist."
Baltimore County officials and other restoration proponents point to published research finding significant reductions in sediment, phosphorus and nitrogen from projects that have been monitored for at least a few years after completion.
Gardina said his staff works to reduce runoff where they can in tandem with stream restorations. Steven Stewart, who oversees stream monitoring for the county, said his office lacks the money to track water-quality after all restoration projects, but in selected cases reductions in sediment and nutrients have been measured.
Minebank Run, a restored county stream, is one of those that's been held up as a success.
But it illustrates how complicated the issue is, and how intractable the debate. A stretch flowing through Cromwell Valley Park north of the Beltway shows signs of erosion, with tree roots dangling four feet above the water. A rock weir put in the channel and a rock wall built along its banks, seen in a photograph taken shortly after the $4 million project was completed in 2005, are no longer there.
"When they're first done, they're amazing projects, they're really beautiful" said Richard Klein, an environmental consultant who frequently represents community groups seeking to limit impacts of development. But as the years pass, Klein said, he's seen a number of completed projects that have begun eroding again.
Klein, president of Community & Environmental Defense Services in Owings Mills, said there are some other county streams restored even longer ago that appear to be holding up, such as Spring Branch.
"The $64 million question is why is that surviving so well, and why is this one failing?" he said, referencing Minebank Run. "Until we can answer that question we may be wasting our money."
Critics say more money and effort needs to be put into reducing runoff to complement stream restoration.
Klein says in Baltimore County's case, it could reduce sediment and nutrient pollution by strictly enforcing laws requiring state-of-the-art runoff controls at construction sites and in new developments. He pointed out an 83-acre, partially developed commercial site near Whitemarsh Run where he said a large area of soil has been bare of grass or other vegetation for years, making it more vulnerable to erosion.
Gardina said Minebank Run was a special case. The stream starts out in the Towson area before flowing to the Gunpowder River, he said, so there's not much open land where runoff could be captured. The eroding section is slated for repairs, he said, and likely would get heavier stones. .
"On any stream restoration project you may get some blowouts and things of that nature," said Ryan, the county restoration manager. He attributed the failure there to unusually severe storms, but said Minebank Run is "not a catastrophic failure. It's still functioning properly."
Officials in Baltimore County and other area local governments note that the Environmental Protection Agency accepts stream restoration as a means of reducing sediment and nutrient pollution for cleaning up the bay. They say credits given for restorations are based on monitoring of finished projects and a review of available research by a panel of experts, many of them local officials and private environmental consultants.
"The yardstick that scientists use for determining a project's success is different than what government managers use," said William P. Stack, deputy director of the Center for Watershed Protection, a nonprofit think tank. Stack, who was co-chairman of the panel reviewing restoration projects, worked for decades for Baltimore city's public works department where he oversaw work on Stony Run, a degraded tributary of the Jones Falls.
"We're doing the best we can with a broken watershed," he said. "We might not be successful at restoring trout or other living resources, but one thing we're pretty successful at is stabilizing the stream and preventing erosion."
Stack said that in built-up urban and suburban landscapes, it could take decades to get enough property owners to put in rain gardens, green roofs and other projects.
"That's a long-term effort," he said, "but you have to put out the fire first."
Stack acknowledged many early restoration projects were built without careful enough assessment of what was wrong with the stream, and claims for the benefits of some projects were overstated. But he said government managers and consultants have improved their techniques, and tried to address criticisms from scientists.
"I think restoration science is still at a pretty early stage, and we have an obligation to learn as much as we can from it and recognize we don't have all the answers," said Erik Michelsen, who manages stormwater control efforts for Anne Arundel County. That county projects spending $450 million on stream restoration by 2025.
Michelsen said the pressure is on local governments to do their part to meet the bay "pollution diet" imposed by EPA, which requires an increasing number of pollution reductions over the next 11 years.
That pressure was among factors that prompted the state to mandate that Maryland's most populous jurisdictions impose a stormwater remediation fee — which has become political fodder as a so-called "rain tax" — to pay for the projects.
"Because of the obligations we've got, we have to move ahead in a time frame that doesn't allow us the luxury of having all the answers," he said. "We have to do something now."