Robert Tudor, deputy executive director of the Delaware River Basin Commission, has seen a model of a Category 3 hurricane landing near the mouth of the Delaware Bay at Cape Henlopen. It’s not pretty.
“The model shows a storm surge of 3 to 7 feet that will impact the bay and the lower river—even inundating the Philadelphia Airport,” Tudor says. He points to the inland flooding around the Chesapeake Bay when the remnants of Hurricane Isabel charged through in 2003.
That’s only one of the disaster scenarios that threaten the delicate but vital Delaware Estuary and its wetlands, a scenario intensified by human activity. We have, in ways, helped engineer the vulnerability of those wetlands, and without them, we could find ourselves in a heap of trouble.
So what’s so important about all that mud, anyway? In a word, life. Wetlands are a breadbasket for aquatic organisms. Most of our commercially important fisheries depend on wetlands.
“One thousand pounds of phytoplankton found in wetlands supports 100 pounds of zooplankton, which in turn, supports 10 pounds of forage fish and, ultimately, just one pound of rockfish such as striped bass or weakfish,” says Jim Chaconas, an environmental scientist with DNREC’s Division of Water Resources.
There is another important function of wetlands that directly impacts human life. “Wetlands are nature’s water filters,” Jacobs says. “They filter surface pollutants and nutrients that would otherwise flow into our aquifers and other fresh water sources.”
Yet this mighty food processing-water filtration system is shrinking. At one time, 36 percent of Delaware consisted of wetlands. Between 1780 and 1992, more than 100,000 acres were lost to agriculture and other development. And as Amy Jacobs, a scientist in the Division of Water Resources, points out, “Almost all of what’s left (223,000 acres) is degraded.”
Roger Jones, state director and president of the Delaware chapter of The Nature Conservancy, has seen a model for sea level that could raise the Delaware Bay up to 38 inches during the next century. “That would inundate about 40 percent of our state’s tidal marshes,” he says.
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Dirtier water for us, and nothing for the weakfish to eat—or for about 130 species of finfish, the second-largest collection of migrating shorebirds in the Western Hemisphere, about a half-million waterfowl, and the clams, oysters and crabs they eat. And don’t forget: The estuary is home to the world’s largest population of horseshoe crabs.
Fortunately, several groups are working together to preserve and restore our wetlands. The Delaware Wetlands Conservation Strategy, an effort by DNREC, other state agencies and partners, outlines six goals for protecting wetlands. Chief among them is sharing information and coordinating protection and restoration efforts.
“I know the joke about committees and three-humped camels,” Tudor says. “But in our case, collaboration has worked well.”
Tudor cites a committee formed by the four states that control the Delaware Estuary—New York, Pennsylvania, New Jersey and Delaware—to find ways of mitigating flooding in the estuary north of Trenton. Working from various flood models, it recently coordinated a release of 15 reservoirs to significantly reduce flood potential.
More of that kind of cooperation is needed to maintain the balance. The Partnership for the Delaware Estuary, a regional non-profit based in Wilmington, is responsible for the 52 percent of the Delaware River Basin below Trenton. Danielle Kreeger, science director for the partnership, says satellite imagery shows a large degree of erosion on the seaward edge of wetlands, which has led to conversion of interior areas to open water.
“While current sediment flow may be OK for natural changes, it is not keeping pace with sea-level rise,” Kreeger says. “Out here, we’re seeing a lot of ponding where grassy wetlands use to be. It’s getting quite scary.
“Sea level rise increments outstrip marsh expansion,” she says. “Throw in the current level of degradation to the marsh we have left, and all it takes is one storm to push the marsh past sustainability and toward collapse.”
Kreeger calls for increasing natural breakwaters, such as oyster reefs, to reduce the force of waves slapping the marsh’s shoreline. Though mud—sediment flow from the river—is essential to preserving tidal marshes, another kind of maintenance and expansion plan is needed for non-tidal freshwater inland marshes.
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“In the case of non-tidal marshes, we need to restore the natural floodplain that has been lost due to reclassification of land away from wetland designation,” she says.
Inland wetlands are crucial to maintaining tidal wetlands because they migrate upland to extend what’s lost to erosion on the shoreline. Think of the entire wetland ecosystem as a giant accordion. When one side, the tidal wetlands, is compressed through erosion, the other side, or non-tidal wetlands, expands and the marsh pushes upland.
But keeping land available for upland migration smacks headlong into the pressure to develop open spaces. Development often walls off land that could become part of that natural migration. Buffers—ribbons of land DNREC manages to protect environmentally sensitive areas from pollutants and nutrient runoff—protect existing wetland boundaries, but do not allow for migration.
“The key to restoring non-tidal wetlands is to take back previously developed land, restore the floodplain, and ensure that sufficient forest buffers are situated around the wetlands,” Kreeger says.
Associate professor of oceanography Christopher Sommerfield of the University of Delaware College of Marine and Earth Studies disagrees with part of Kreeger’s assessment, believing the historical picture indicates a system that is still relatively in balance.
“You’re always going to see erosion at the shoreline edge of our marshes,” Sommerfield says. “Marshes are hurt by wave energy that is normally weakened by the presence of mud flats that form in front of the shoreline. A lack of these mudflats increases the rate of erosion.”
All marshes resulted from mud flats that existed long ago. Yet the disappearance of these flats are not the main threat to the wetlands, says Sommerfield. The rate of sediment accretion, he says, is the key. Sommerfield’s lab can measure the rate of accretion, or upward development of marshland needed to sustain marsh development.
“We’ve taken core samples of our marshes, and it appears those marshes are not sediment starved,” Sommerfield says. “Their development matches what our lab results suggest development should be over time.”
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So Sommerfield has turned his attention from the shoreline to the upland side of the marsh. That’s where he and Kreeger find common ground.
“The upland migration of marsh due to the natural forces of erosion is being hampered by commercial development, which has erected a kind of fence preventing the marsh from moving farther inland to restore what is lost to erosion,” Sommerfield says.
Where that fence can be built in a way that balances the need for development and wetlands preservation is the issue.
“About 20 to 40 percent of our total wetlands are not regulated at all,” says Jacobs. “These are areas at the drier end of wetlands, and because they are drier, they’re easier to drain and develop.”
DNREC tried about 10 years ago to gain regulatory control over these upland wetlands, “but lost out to the agriculture lobby,” Jacobs says. “Surrounding states are currently doing a much better job of regulating these areas under their jurisdiction.”
So DNREC, along with private, non-profit organizations, is purchasing tracts of wetlands for protection. Similarly, the Delaware chapter of Ducks Unlimited has acquired almost 13,000 acres of wetland areas since its program began in 1937.
“We’re losing land and gaining people,” says Ducks Unlimited state chairman Howard Wilkins. His group, with various partner organizations, committed $1 million in 2008 for maintenance and rehabilitation efforts, water control and scientific services.
The Nature Conservancy, a national organization that has preserved almost 120 million acres of land worldwide, has spent $70 million since 1991 to purchase land for protection in Delaware. It now holds 30,000 acres of land necessary for wetland preservation. “Our plans are to expand our conservation acreage over the next 15 to 20 years to include an additional 90,000 acres that will include wetland areas,” Jones says.
He believes Delaware needs to strengthen its three major land preservation programs: open space, agricultural land preservation and the state forest land program.
“Funding for those programs comes from the state’s real estate transfer tax,” Jones says. “Until about two years ago, that tax was providing about $10 million for land preservation. In 2008 the transfer tax funding for land preservation fell to $6 million.”
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Reclaiming developed freshwater wetlands and restoring natural floodplains is vital, Jones says, especially in view of potential sea level rise from global warming.
“The smart thing to do is to try and protect and expand as much of our upland wetlands as possible,” Jones says.
He believes cooperating with developers can help overcome anti-regulatory feelings and, perhaps, preclude the need for regulation. “Helping private landowners develop programs that promote conservation goals can help us achieve greater results than by strict enforcement of regulations,” Jones says. “Such a mutually beneficial regulatory framework yields more results because it prevents turning an asset into a liability.”
Jones says onerous regulation tends to place additional costs on landowners, and that the threat of stricter regulation may promote habitat destruction by inciting landowners to, say, clear cut an area of forest in advance of regulations that would prevent such cutting. Clear cutting and destruction of plant life in general affects the natural condition of the upland marsh and changes the dynamics of the water supply.
Jacobs says much can be done to restore wetlands that have been degraded through ditching and channeling.
“Channeling disconnects the stream from the wetland,” she says. “Bypassing the wetland’s natural filtration capability means nutrients and pollutants in the stream that result from runoff from developed areas reaches open water with those pollutants still present.”
Reconnecting stream and wetland improves flood protection, Jacobs says. “Flooding is mostly man-made.”