The delicate, slow task of restoring 3 Long Island wetlands

The securing of a federal grant in July to restore three coastal wetlands in Suffolk County is the start of a lengthy process to make sure the work doesn't do as much harm as good.

The selection of the sites — Cupsogue Beach Marsh, Scully Marsh and the East Islip Preserve — and the securing of funding represent years of advance work, including collecting data on tidal flooding, risk assessments and a cost-benefit analysis. The cost of restoring Cupsogue, for example, is estimated at $2 million, with losses averted totaling $50.6 million.

Now that the funding is secured, the next step will be surveying and modeling, which will continue until February. Then comes conceptual design of different alternatives starting this fall and continuing until next spring. Finally, environmental review and permitting is expected to last from January to September 2025. The earliest possible date to begin construction is spring 2026.

That’s nearly four years from the germ of the plan to breaking ground.

For many environmental restorations, the preparation takes far longer than the job on the ground. "You don’t want to screw up the wetland in trying to restore it," said Adrienne Esposito, executive director of Citizens Campaign for the Environment in Farmingdale.

What’s so complicated?

These projects generally require years of planning: applying for funding; hiring an environmental engineering firm; conducting site surveys; developing proposals for restoring the site; submitting proposals for public comments; and seeking more funding to carry out the work itself.

Any work conducted in and around streams or wetlands must be reviewed and permitted by the appropriate agency, such as the state Department of Environmental Conservation or the U.S. Army Corps of Engineers, which has jurisdiction over tidal wetlands.

The three Suffolk wetland sites present several specific issues.

Site surveys show the three wetlands suffer from loss of vegetation that in a healthy marsh would help absorb wave energy and stabilize shorelines. Wetlands crisscrossed by mosquito ditches and mired in excess nitrogen can’t channel storm surges and absorb rainfall as effectively as a healthy marsh with thriving native grasses.

The county plans to use FEMA’s Integrated Marsh Management (IMM) method, which involves filling old grid ditches to restore the natural hydrology of the wetland.

Filling these ditches raises marsh elevations, which improve growing conditions for native marsh grasses and improves tidal flow — which in turn allows sediments to accumulate, enhancing further growth. The improved habitat fosters greater biodiversity as well.

The initial $1.29 million grant for the project will come from FEMA's hazard mitigation program; an additional $2.9 million FEMA grant is expected to pay for construction, and the county will contribute the remainder of the total project cost of about $4.3 million.

What can go wrong?

The risks when a project goes awry can be significant.

A decade or so ago, the Town of Southampton tried to reduce erosion at Tiana Beach by building a revetment, a barrier constructed of rocks held in place by wire mesh, then covered with sand. But the beach is "probably one of the most prolific nesting areas on the East End" for horseshoe crabs, according to Kevin McAllister, president of the environmental nonprofit Defend H2O, based in Sag Harbor.

When the sand washed away last winter, McAllister said, the barrier became a "killing field" during the spring egg-laying season. The crabs' legs caught in the exposed mesh as they tried to pull themselves onto the beach to lay their eggs, and volunteers had to work to free them.

The studies, analyses and permitting thus are intended to protect ecologically fragile sites and make sure the proposed cure actually works — and avoids unintended consequences such as mass mortality of a threatened species.

"Living things and living communities are both complex and complicated," John Turner, senior conservation policy advocate at Seatuck Environmental Association, wrote to Newsday. "And it can be easy to go wrong on an ecological restoration project, even with one that has the best of intentions."

Does the work pay off?

One project that is closer to completion is an effort to restore the connection between Bellmore Creek north of the Mill Pond in Wantagh and the bay to the south. It has been in the works since at least 2018, when Seatuck applied for a grant from the DEC to study the best approach.

A dam that impounds the Mill Pond is only a few feet high, but it's imposing enough that fish such as river herring and American eel can't leap past it. Populations of these fish, which are important to marine and riverine food webs, have been declining all along the East Coast because hundreds of small dams block their access to upstream habitat.

The project nevertheless required careful study. "The hydrology is really complicated," said Enrico Nardone, executive director of Seatuck, which is directing the project. "You’ve got to get it right."

Seatuck chose Princeton Hydro, a firm with experience in wetland and stream restoration, to propose options.

"Everything was on the table," Nardone said, including removing the whole dam to restore the original stream. "In no other situation that I’m aware of on Long Island has anyone really considered taking a dam down," Nardone said.

It turned out that removing the Mill Pond dam wasn't an option. The streambed had been lowered to channel it through a culvert that runs under Merrick Road opposite the dam. If the dam were removed, Princeton Hydro determined, the stream banks would erode as the brook attempted to reestablish its original elevation.

In the end, the only viable choice was a metal "technical ladder" that allows fish to scale the dam — the least attractive option, and, some evidence suggests, a less effective one.

That process thus became a reckoning of the ideal versus the possible, Nardone said. "You don’t really know what the project is going to be until you do the analysis and the planning."

Seatuck recently secured a second grant to do the work. Once the contractors get the final go-ahead, the ladder will be built in just two or three days.