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DOT learns as it goes

A mute swan struggles to gain enough speed to get airborne at Dutchman's Creek Mitigation Site.
Staff Photo By Mel Nathanson

speak_outWetlands and I-540: Discuss concerns about DOT preservation of wetlands and the construction of I-540 in our forum dedicated to the Outer Loop.
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The Canada geese have returned to the old farm pond on Dutchman's Creek. The earthen dam, partially washed out by Hurricane Fran, has been replaced, and by this time next year swamp dogwoods, tag alders and sugarberry trees should stand knee high along the shore.

The pond lies 15 miles south of where the state Department of Transportation is building the Outer Loop. But without the pond, the six-lane highway across northern Wake County would not be possible.

By law, DOT must make up for wetlands it destroys -- by restoring, enhancing or preserving wetlands elsewhere. DOT is remaking wetlands at Dutchman's Creek near Lake Wheeler because it buried wetlands under the Outer Loop.

It's part of the largest wetland mitigation DOT has ever attempted in the Triangle. The department plans to restore or preserve about 200 acres of wetlands throughout Wake County to compensate for 60 acres it will bury under the northern arc of the Outer Loop.

Although beavers have done it for eons, humans still struggle to find the right mix of water, soil and plants that make functioning wetlands. DOT has as much experience restoring wetlands as anyone, but the long-term viability of most of its sites, including Dutchman's Creek, remains uncertain.

"To be truthful, our Department of Transportation has come a long ways in its wetlands mitigation program," said Ron Ferrell, manager of the Wetland Restoration Program at the Department of Environment and Natural Resources. "But there's a lot of things that go into making a wetland system. We don't really know how long it takes to put all that back."

A decade ago, most of DOT's mitigation attempts failed, Ferrell said. The ground would end up too wet or too dry, or the trees and shrubs wouldn't take.

One failure is at the intersection of I-40 and the Outer Loop, where DOT scraped tons of soil from the edge of a pond in hopes of creating a forested wetland to make up for one destroyed by the Outer Loop. Instead, so little soil remained that the trees died and were replaced by marsh grasses, said David Schiller, who supervises DOT biologists who try to limit the environmental impact of highways.

"It is a wetland, but it's not the habitat type that we were aiming for," Schiller said.

No one ruins more wetlands in North Carolina than the DOT. Its highways will destroy an estimated 5,000 acres between 1998 and 2007. For every acre of wetlands the DOT destroys, state and federal laws require it to preserve 10 acres, enhance or restore two to four acres or create two new acres.

DOT has stepped up its efforts as state and federal regulators have clamped down. The department preserved or restored 1,600 wetland acres before 1994; since then, it has completed 11,000 additional acres, with several thousand more in the works.

The department is learning with experience, according to two East Carolina University researchers hired by the DOT. Mark Brinson and Rick Rheinhardt say the majority of DOT restorations they evaluated were ecologically viable.

"They've been in this business for a short period; in fact we've all been in this business a short period of time," Brinson said.

Among DOT's restoration projects are 12 acres of former bottom-land forest along New Light Creek in northern Wake County that were cleared, ditched and drained for farming in the 1950s. The department refilled the ditches, dismantled a makeshift levee along the creek and planted thousands of water-loving trees.

But like the pond on Dutchman's Creek, most DOT wetland restoration sites are too young for scientists to know whether they'll thrive, Schiller said.

"You can't show you are successful until you've reached five years, and we haven't reached that on most of our sites," he said.

DOT has done a good job at Dutchman's Creek so far, says John Argentati, an avid birder and member of the Audubon Society who was so fond of the old farm pond and a nearby beaver pond that he built a house in the Bradford Place subdivision just up the hill.

"If nothing had been done, we would have lost that pond," Argentati said. "It would have just been a field, and that would have little value to wildlife."

The word "wetland" describes a range of environments, including swamps, flood plains and low-lying hardwood forests where the ground may be only intermittently wet. Once considered wasted land, wetlands are now prized for filtering surface water, preventing flooding and providing homes and food for wildlife.

By law, DOT must avoid as much wetlands as possible when it builds a road. The half cloverleaf on the Outer Loop at Falls of the Neuse Road helped the state sidestep three acres of wetlands, for example. But with a 26-mile highway cutting across 800 acres of northern Wake County, avoiding wetlands altogether was impossible.

At an average of $10,000 an acre, DOT has $170 million in wetlands projects in various stages of completion. Buying the Dutchman's Creek property and restoring the pond cost nearly $1.9 million. In addition, the department is paying private companies and DENR $49 million for wetlands work.

Wetlands that were drained or filled often make good candidates for restoration. Last year, the DOT placed ads in newspapers seeking wetlands to buy and restore. The department also hires private companies to find, acquire and restore wetlands on its behalf and is paying DENR to locate wetlands and streams in need of restoration.

Once DENR and the Army Corps of Engineers declare a wetland restoration a success, DOT gives the property to another government agency or private conservation group, under the condition that it never be developed.

The Audubon Society objected to DOT's initial plans for Dutchman's Creek, which called for eliminating the pond in favor of a bottom-land hardwood forest, Argentati said. After negotiations, the DOT agreed to create the five-acre pond.

"Overall, the DOT did pretty well by us," Argentati said.

By next year, Argentati expects the new pond to look like the mature beaver pond just upstream, where he has counted as many as 200 birds on a winter's day. One morning this week, Argentati pointed out some of the birds already visiting the DOT's pond, including a mute swan, a great blue heron and a pair of great egrets.

"Hear that? That's green heron," he said, clutching the National Geographic Society's field guide to birds and searching the sky. "This is such a great place."


Staff writer Richard Stradling can be reached at 829-4739 or rstradli@nando.com



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