Restoring Streams to Their Natural Glory
- Jessica Snyder Sachs
- Jun 01, 2002
FOR YEARS, Patsy Savage watched helplessly as the turbid Soque River gobbled up her family's north Georgia homestead. The problem began in the 1980s, when river dredging and upstream development triggered a vicious cycle of erosion. Over the next decade, the section of the Soque that passed through the Savage farm became a voracious brown monster that scoured away 60 to 100 tons of bordering pasture each year.
In the early 1990s, an Environmental Protection Agency (EPA) study of tributaries to Georgia's Chattahoochee River revealed that the farm-lined Soque was the biggest source of smothering sediment that was killing off the sensitive aquatic life, filling in vital reservoirs and raising the costs of purifying drinking water for downstream metropolitan Atlanta. In 1998, the EPA teamed with a local conservation group, the Upper Chattahoochee Riverkeeper, to launch an ambitious project to restore the Savages' section of the river to the size, shape and depth that nature originally intended. Four years later, this 1,200-foot channel remains a showcase for the emerging science of natural stream restoration, with erosion at near-undetectable levels.
Pioneered in Montana and Colorado in the early 1980s, natural stream restoration took off in the late 1990s, largely as an effort to undo the legacy of damage left by decades of government-sponsored programs to move, straighten, dredge and otherwise alter waterways to stop flooding, or get them out of the way of farms, roads and other development.
"Obviously we've been messing with streams for ages," says watershed hydrologist Dani Wise-Frederick, director of the recently established Stream Restoration Institute at North Carolina State University. "What's new is our understanding that rivers are self-forming and self-maintaining. If you relocate, straighten or otherwise alter a river, it's going to try to carve its way back to its natural position."
To fight this erosive force, old-style engineering practices relied on heavy reinforcement of collapsing banks with concrete and wooden retaining walls, as well as continual channel dredging to clear the sandbars formed when slowing waters drop their silt load. "But such Band-Aid approaches only displace problems up or downstream," says Wise-Frederick. Only the re-creation of a stable river system closely mimicking what Nature originally carved, she explains, will stop the cycle of erosion, habitat degradation and wildlife loss.
Indeed, while sewage and toxic chemicals remain major threats to America's 3.5 million miles of rivers and streams, the silt from erosion also causes severe ecological problems. "We now realize that very little disturbance to a river system can cause serious impacts," says EPA wetlands scientist Jennifer Derby. "People think we have natural, stable rivers all over the place," adds David Rosgen, a pioneer in stream restoration. "In fact, we've altered most of them in one way or another." Rosgen's Colorado-based firm is among the companies that have spearheaded the efforts to reverse this damage in the West, though often at an admittedly high cost. In many cases, their clients are willing to take whatever steps are needed to restore their ranchland streams to their former natural glory.
A case in point: Two years ago, Bostonian David Wimberly, an avid fly fisherman, bought the ranch of his dreams in Montana's Ruby Valley, crowned by a spring gushing crystal-clear water at a dramatic rate of 30 cubic feet a second. The spring water flowed for nearly a mile through a former pasture before emptying into the adjoining Ruby River.
But what should have been an unparalleled trout stream had been "cattle bombed," says Scott Gillilan, the river hydrologist Wimberly called in to restore the waterway. Nearly 100 years of heavy grazing and trampling had collapsed the waterway's banks, tripled the channel's width, and heavily silted over its once trout-friendly gravel bed.
Before bringing in bulldozers to resculpt a more natural and stable channel, Gillilan consulted with fisheries biologists, aquatic entomologists and plant ecologists to determine how to best "bioengineer" the stream's historically rich ecosystem. "In good condition, western spring-fed creeks are the most productive fisheries around," he explains. "To achieve that, we knew we needed a lot more diversity, with a healthy assemblage of aquatic insects and other macroinvertebrates."
To make the stream inviting to such creatures, the restoration included the construction of aerating riffles, pools and streamside vegetation. Gillilan also created several waterfowl ponds in a nearby hayfield that yielded the kind of boggy soil that would prove ideal for building new stream bank. The cost for restoring a little over three-quarters of a mile of stream was high, says Wimberly with no regrets, adding: "My son was out walking the stream and he counted 18 different places where trout were spawning."
The Wimberlys were not the only people pleased with the results. Scientists with the EPA and Army Corps of Engineers have praised the dramatic reduction in the stream's discharges of sediment and fertilizer into Montana's troubled Ruby River.
Admittedly, says Gillilan, a spring-fed creek flowing across flat ground is among the easiest to restore. "The work becomes much more complex when you have runoff and the stream has to respond to flows from the surrounding watershed," he notes. "Then you really need to nail it, placing every meander and pool in the right place."
Such was the challenge faced by fisheries biologist Don Cardin and long-time conservationist and rancher Ed Cox on Cox's 2,000-acre ranch in the western foothills of Colorado's Rocky Mountains. When Cox bought the land in 1994, he set Cardin to the task of restoring its main waterway: the Gunnison River's fast-moving Lake Fork. Previous owners had straightened and gravel-mined what had once been a winding stream, walling up its banks to keep spring floods out of adjacent fields. Fighting to return to its original course, Lake Fork was tearing away its banks, digging a wide channel while depositing silt in a braid of sandbars and unstable islands.
For five years, Cox and Cardin watched the out-of-control waters chew away at the stream banks and pull down bordering trees. "Spot fixes won't work when a river's this far gone," explains Cardin, who entirely rebuilt a mile of channel following methods pioneered by Rosgen.
Rosgen's techniques entailed carefully classifying the watercourse according to its grade, sediment type, historic flows and natural vegetation. The rest was mathematics, with category-specific formulas to calculate a more natural width-to-depth ratio and the ideal spacing and location of meanders, riffles and pools. The result was a stable river and functional floodplain with a return of water quality and aquatic life.
The Lake Fork's reconstruction, completed in the fall of 1999, has now successfully withstood two spring runoffs. "The river's still where we put it," says Cardin, "and its trout have increased tenfold."
Restoring native trout populations has become a major focus of Ted Turner's stream-restoration efforts on his ranchlands in Montana and New Mexico. Working with state fish and game biologists, the media executive's plans include removing nonnative trout from as much as 80 miles of streams. "We're hoping to make the streams safe havens for native fish that occurred there historically," says biologist Mike Phillips, who oversees Turner's wildlife conservation programs.
The Turner team has also begun a long-term project in New Mexico to restore 1,000 acres of wetlands adjacent to the Rio Grande River. The team is physically removing nonnative stands of saltcedar along the river banks, which will allow cottonwoods and other native plants to recolonize the area. The goal: to provide habitat for native wildlife. "By getting rid of the saltcedar, which soaks up huge amounts of water, we will be directly putting a lot of water back into the river," says Phillips. The project represents a huge commitment on Turner's part. "It will take between 10 and 20 years to complete," adds Phillips, "but we consider such efforts as being part of responsible land ownership."
Endeavors such as these are fueling tremendous enthusiasm for stream restoration projects across North America. "In the last few years, we've seen a rapid shift in policy," says EPA's Derby. "Just as regulations have long required developers to mitigate for wetland destruction, we're now beginning to require restoration and compensation whenever stream impacts occur."
In North Carolina, for example, stream restoration requirements kick in whenever developers disturb more than 150 feet of stream. Specifically, developers must find and restore a minimum of 100 feet of degraded stream for every 100 feet of stream they disturb. In Virginia, a similar program requires developers wanting to alter a stream to pay into a fund that can be tapped for other stream-restoration projects.
While many conservationists hope other states will follow North Carolina and Virginia's lead, stream restoration is not without controversy. "As much as I'd like to believe in restoration, I'0ve never seen a stream returned to a predisturbed condition once it has been degraded," says Charles Gougeon, a biologist with the Maryland Department of Natural Resources. "What I fear is that false promises of stream restoration will open the door to destruction of what few healthy streams we have left."
Part of the problem, says Gougeon, is trying to apply restoration techniques developed in the wide-open spaces of the West to the densely populated and overdeveloped East. "If the overriding problem to stream quality is urban development, as it is here in Maryland and most of the East," he adds, "no one is going to bulldoze miles of homes and roads to reestablish buffer zones of vegetation to filter and slow runoff."
The bottom line, adds Gougeon, is that there's no substitute for preserving those pristine streams that have somehow escaped degradation. "The thing to do," he says, "is take the money that would otherwise be spent on questionable restoration efforts and use it to find the finest streams and target them for protection through land acquisition."
In the end, stream restoration's greatest potential may be in the wide-open West, where the effects of mining, overgrazing and counterproductive flood-control projects often can be reversed with sufficient money and expertise. "I've been involved in a lot of restoration projects," says Cox, reflecting on the successful efforts on his ranch. "But never have I seen such a dramatic recovery of habitat to the state Nature originally intended. The fact that we have this technology is exciting."
NWF's Northeast Natural Resource Center is actively involved in a major stream restoration project on both private and public lands along Vermont's White River and its tributaries, where streambank erosion, runoff pollution and other factors have caused major declines in native trout stocks. The congressionally authorized project is the only one of 56 U.S. Forest Service pilot programs that focuses on river, rather than terrestrial, habitat restoration. To learn more, see our Northern Forest page.