The Army Corps of Engineers is proposing a storm surge barrier for Great Egg Harbor Inlet in southern New Jersey (Illustration from US Army Corps of Engineers).

Army Corps flood gates would hurt Pinelands river, National Park Service warns

Massive flood gates being considered for the mouth of the Great Egg Harbor Inlet (southern New Jersey) would likely impact the ecosystem of a protected river that runs through the Pinelands, the National Park Service has warned.

In an April letter to the Army Corps of Engineers, the National Park Service knocked the federal agency’s initial study released in March which looked at possible flood mitigation strategies along 3,400 miles of New Jersey’s back bays.

The letter singled out one idea in particular: the construction of a $3.9 billion storm surge barrier at the Great Egg Harbor Inlet, the body of water separating Absecon Island and Ocean City.

Storm surge barriers consist of moveable gates that stretch across the mouths of inlets and close during storms to prevent water from entering the bays and inundating nearby homes.

Similar structures have been built in the Netherlands and London.

But park officials said such a project could disrupt fish migrations, change tidal flows, hurt water quality and affect the ecosystem of the Great Egg Harbor River, a 129-mile waterway mostly located in the Pinelands National Preserve that drains into the Great Egg Harbor Inlet and Atlantic Ocean.

Building gates there would likely affect the waterway by “altering the tidal and flushing regime in the estuary; degrading the water quality in the river and estuary by blocking the draining of the river during a storm event… and by forever altering the scenic viewshed of the lower river and estuary,” the National Park Service wrote.

The Great Egg Harbor River, which starts near Berlin and runs past Corbin City, is part of the National Park Service and was designated part of the National Wild and Scenic River system in 1992.

Fred Akers, Great Egg Harbor Watershed Association administrator, worries that a storm surge barrier at Great Egg Harbor Inlet could restrict the flow of water into tributaries upstream depending on how they are built. There may be secondary impacts on fish that swim from the ocean into the river too, he said.

"These things are going to have to be big," Akers said. "The devil will be in the details."

The river is home to a number of threatened and endangered species, including bald eagles, peregrine falcons and bog turtles, and contains ecologically significant tidal marshland, said the National Park Service, whose concerns echo those of environmental groups and the Army Corps itself.

In its report, the Army Corps said tidal flow, tidal range, water quality and flora and fauna could be significantly affected, but quantifying the extent won't be possible until an "environmental impact statement" is complete. Barriers are also viable at Absecon Inlet, but not Hereford or Brigantine inlets, according to the initial study.

The Army Corps is conducting modeling to learn how a storm surge barrier at each inlet would affect tidal flow, circulation and salinity, said Spokesman Stephen Rochette.

It's difficult to predict impacts, he said, due to the unknown frequency of gate closures.

"We're working with resource agencies to develop a conceptual ecological model of the region that will be used to help evaluate storm surge barrier impacts," Rochette said.

Other groups are wary too.

In New York, the Army Corps has proposed five different proposals for mitigating flooding from the Hudson River, including a storm surge barrier that has sparked backlash from environmentalists. One of the proposals is for a barrier stretching from Sandy Hook, New Jersey to Rockaway, New York.

Jeff Dement, fish tagging program director for the American Littoral Society, worries that recreational anglers could be hurt if such structures are erected in North and South Jersey.

"If we close the flood gates," he said, "then fish can't leave the estuaries... Recreational fishing would be diminished."

He and others are calling on the Army Corps to turn its attention away from building hard, concrete structures and toward restoring natural barriers.

In separate letters, the National Park Service and Fish and Wildlife Service both criticized the Army Corps for not focusing enough on living shorelines and other "non-structural alternatives."

The park service said the Army Corps should look more deeply into relocating people away from the water.

"(The report) focuses heavily on structural alternatives and did not appear to spend an equal amount of analysis on non-structural alternatives," the NPS wrote.

Some non-engineered flood mitigation projects are already underway in South Jersey. In Ocean City, for instance, the Army Corps is placing hundreds of tons of rock around Shooting Island to rebuild the eroding wetland as a buffer against storm surges.

"The Service prefers the selection of Engineered with Nature or Nature-based alternatives," the Fish and Wildlife Service wrote in its letter.

The Army Corps, though, has said that structural options have more of an effect on reducing flooding, according to presentations given to Ventnor residents last September. Rochette said the agency will continue to analyze elevation, relocation and flood-proofing as possibilities.

The Back Bays study, launched in 2016, is the first step in the agency's decade's long look into stemming flooding along the bays, where there has historically been less mitigation investment compared to the oceanfront. None of the ideas outlined in the March report are being pursued or currently funded.

Between 2030 and 2050, Atlantic City alone would see more than $300 million in average annual damages if no flood mitigation projects are pursued, the study estimates. The earliest construction could begin is 2030.

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