Some shore towns use bayside islets to ease island flooding
OCEAN CITY, N.J. (AP) — At last Thursday’s high tide, a tiny tugboat named Bonnie pulled a red barge through Great Egg Harbor Bay.
It headed to Beesleys Point 2 miles away to be filled with up to 300 tons of rock before returning to Shooting Island, an eroding wetland within eyesight of Ocean City’s back bay.
As shore towns grapple with how to mitigate flooding, some are turning their attention away from building hard, concrete structures, such as seawalls, and toward restoring more natural barriers.
Officials say some of these natural barriers, which have been slowly disappearing for years, can be rebuilt as a buffer against storm surges. The small, bayside islands, or islets, dot larger barrier islands across Atlantic and Cape May counties.
Ocean City’s once-150-acre Shooting Island is the largest such endeavor in South Jersey.
The city is restoring what was once a dredge material site by stocking it with oyster habitats and placing a rock wall around a portion of it.
The island could be gone by 2100 if nothing is done, the city says.
“These bay islands are a first defense against flooding,” said Junetta Dix, environmental director of Act Engineers Inc., the firm tasked with developing a long-term dredging plan. “If it’s flooding in your back door and you have hard wood floors, it comes straight across. But if you have big, deep shag carpets, in this case it’s vegetation and rocks, then it hits that and it slows down and it dissipates.”
Work began last week on the $2.75 million project, funded partially by a $2.6 million federal grant. A crew of construction workers in hard hats were continuing to install 2,700 feet of rock sill along the island’s west side on last week, even as pieces of the marsh fell off.
Once that’s complete, they will place 1,450 feet of open concrete blocks that lock together on the shoreline for oyster habitats. Plants may be added during another phase of the project if the city applies for and receives dredging permits, which takes years.
Using bay islands for flood mitigation is a budding concept in New Jersey. It’s also been done in the Chesapeake Bay area.
For years, officials in Margate and Ventnor have been eyeing Shelter Island off Ventnor as a way to protect the vulnerable back bay. In 2014, the cities hired the Coastal Research Center to study the island.
In the center of the marshland is a giant hole. Shelter Island’s center was dug out in the 1920s to 27-foot water depths to build Ventnor Heights. Researchers with the CRC estimated that 900,000 cubic yards of sediment would be needed to fill that hole, bring the island to one-foot of elevation and restore 47 acres of marsh.
Then, the hope is that it could act as a buffer against boat wake action and nor’easters.
“Everyone is taking a new look at (flood mitigation)” said Jim Rutala, Ventnor’s grant writer. “Our greatest exposure is no longer the ocean front. It’s the back bays.”
Even as the concept gains momentum, it’s not without controversy.
Some have pushed back against the idea of altering natural habitats with dredge spoils, while others have reservations about the high cost of such projects amid a lack of empirical evidence that they mitigate flooding.
“It makes no financial sense to me and we strongly suspect based on our research that (the Shooting Island project) may actually exacerbate flooding,” Suzanne Hornick, board member of Ocean City organization Fairness in Taxes, said of the restoration being done in Ocean City.
Donna Moore, who chairs the group’s environmental committee, is concerned that the rock sill placed on the Shooting Island’s northwestern side will prevent water from draining back into the bay from the streets after nor’easters.
Other similar projects have been successful though, said USACE Project Manager Monica Chasten.
Mordecai Island off Beach Haven was restored in 2015 without flood mitigation in mind. The Army Corps of Engineers placed dredge spoils on the 45-acre salt marsh, initially as a way to reuse the silt removed from the bottom of nearby bodies of water and stop erosion.
But after its completion, Chasten said, nearby landowners noticed a difference in wave action in the bay.
“You can see the waves breaking further out,” Chasten said. “It’s like a speed bump.”
Right now, the Army Corps only has anecdotes to justify such undertakings.
Over the next year, Chasten said, the Army Corps will collect data on the impact that restoring Mordecai Island had on reducing wave action, and later look at whether the project actually protects residential properties from flooding.
“All of these projects are still learning activities,” Chasten said. “There has to be that realization out of the gate. ... But it’s a simple no-brainer. We build these islands, and they break waves.”