Army Corps of Engineers mulls massive plan to protect NYC from storm surges

It’s being presented as vital to protect New York Harbor from the expected increasing intensity of storms in an age of worsening climate change. But according to local environmentalists, the Army Corps of Engineers’ plan to build a system of off-shore barriers and land-based dykes might spell doom for the Hudson River.

To protect New York City and the towns and cities on New York Harbor and up the Hudson River from storm surges, the Army Corps of Engineers is thinking about building massive off-shore barriers and land-based dykes and floodwalls in and around New York Harbor.

The Corps’ New York-New Jersey Harbor and Tributaries (NYNJHAT) Coastal Storm Risk Management Feasibility Study, which arose from its comprehensive study of the North Atlantic Coast following Hurricane Sandy, consists of six alternative plans. The study is co-sponsored by the state Department of Environmental Conservation (DEC), the New Jersey Department of Environmental Protection (NJDEP) and New York City.


On July 11, the Corps held a public meeting at the Hudson Valley Community Center in Poughkeepsie. The meeting, which was attended by more than 100 people, was the last of three public meetings held by the Corps (the other two were in New York City) as part of the study’s scoping process required by the National Environmental Policy Act (NEPA). Bryce Wisemiller, the Corps’ project manager, and other staff presented brief overviews of each of the plans, which are also posted on the Corps’ website. The Corps is accepting public comments until Aug. 20 and by late fall will narrow down the alternative plans to two.

Riverkeeper is raising the alarm about the potential construction of in-water barriers, which would be fitted with gates that would be closed during a storm. “All of the alternatives the Corps has put together for consideration, except for one, includes big barriers built in the water in the inner and/or outer harbor which are designed to completely block storm surges from flooding the city and low-lying areas along the tidal waters,” said Riverkeeper patrol boat captain John Lipscomb, who attended all three meetings.

NY/NJ Outer Harbor Barrier (Alternative 2), Sandy Hook to Rockaway. See the other alternatives here.

The plan with the most expensive price tag — $30 to $50 billion — would install barriers from Sandy Hook to the Rockaway peninsula, under the Throgs Neck Bridge as well as on the Hackensack River, Raritan River, Passaic River and Jamaica Bay. This plan, says Lipscomb, would devastate the Hudson. “It would completely close off the harbor,” he said, resulting in numerous negative impacts, including inhibiting the migration of fish; increasing the concentration of pollutants in the river and harbor; causing sediment build-up and possibly a change in salinity; and restricting rainstorm flood waters up-river, as occurred during Hurricane Irene. Such an impediment of the Hudson’s natural tidal flow would result in the “slow death” of the river, according to Riverkeeper’s statement.

In his presentation, Wisemiller emphasized the economic risks caused by storm surges. He noted that the study area is the largest and most densely populated on the North Atlantic coast, comprising 2,150-plus miles and 900-plus miles of affected shoreline with a population of approximately 16 million.

“It’s one of the nation’s largest economic drivers, one of the oldest regions in the country and it’s very vulnerable to flooding, as we saw in Sandy,” he said, noting the New York metropolitan area contributed $1.6 trillion to the gross national product in 2016. In evaluating the best plan, which would ultimately be funded by Congress, “we need to show that the benefits outweigh the cost,” he said. “The economy is a big driver.”

According to Wisemiller, the federal government has committed $15.7 billion in post-Sandy recovery and shore-resilience projects for the New York metropolitan area. He projected a map showing current shoreline projects underway in the harbor, such as the construction of floodwalls and dykes.

Maps of the six plans were outlined in poster boards exhibited around the room and in Wisemiller’s PowerPoint presentation. Four of the plans involve constructing massive barriers, which would be fitted with gates that would allow passage of ships and be closed during a storm. They would be positioned either at the entrance to the harbor and/or along the Arthur Kill, Verrazano Narrows and Pelham Bay, and below the Throgs Neck Bridge at the entrance to the East River.

As mentioned, the most expensive plan, Alternative 2, which has an estimated cost of $30 to $50 billion, would entail the installation of a five-mile long barrier stretching from Sandy Hook to Far Rockaway, along with multiple barriers on the rivers feeding into the harbor. What’s being called Alternative 3b would have barriers on the aforementioned bays and kills along with Jamaica Bay, Coney Island and at Jersey City, plus surge barriers would be installed at Newton Creek and other “localized creeks” and at Coney Island and Jersey City. Alternative 4 would entail installing barriers on the Hackensack River, Gowanus Creek, Coney Island, Newton Creek and Pelham Bay, with dykes and floodwalls installed at communities on the Hudson.

Alternative 1 doesn’t contain any changes and simply acts as a baseline for the other plans, showing the coastal management improvement projects currently under construction or planned, Wisemiller explained. “We’re trying to get additional information on these which will be documented in a report released this fall,” he said.

Alternative 5 consists solely of the shoreline-perimeter measures, with no barriers. Levies, dykes and/or floodwalls would be constructed along the shorelines of Jamaica Bay, Gowanus Creek, and other low-lying areas as well as along the Hackensack River and in some Hudson River communities. The plan is the least expensive being proposed, with a price tag of $2 to $4 billion, and it is supported by Riverkeeper.

Wisemiller showed a chart with the various projections for sea level rise. He said the Corps is using the projections as the basis for the design of its plans. “We’re using the one-percent probability storm, which would occur every 100 years statistically. That would cause a surge of 12 feet minimally up to 20 feet. We’re using that plus three feet.”

Maeslant Barrier, near Rotterdam, was shown as an example of what such structures would look like (Army Corps. of Engineers)

No other information on the design of the barriers was provided. Wisemiller showed images of massive surge barriers in New Orleans, on the Thames in London, in St. Petersburg and at Rotterdam, each of which had a different design. “All have opening and closing gates,” he said. “There are no seawalls or permanent closing structures.” He noted that the surge barrier in Rotterdam, which has 1,200-foot-wide entrances, is the “largest moving object in the world”; the gates close off a three-mile-estuary area, which he said “is very similar to this area.” He also showed images of floodwalls in New Jersey, New Orleans and Martha’s Vineyard (“similar to one in construction next year on the south shore of Staten Island), reviewed “nonstructural” measures, such as lifting homes up, and natural and nature-based features, such as a tidal marsh and vegetated dune; these features “can hold a few feet of surge and would be added to other features in the plans.”

Wisemiller said the Corps will release a draft report in late fall, which will narrow down the alternative plans under consideration to two. Sixty days after that, the Corps will decide on a “tentatively selected plan” and conduct an Environmental Impact Study, with more public meetings.  In spring of 2021 the final report will be released, which will be submitted to Congress the following summer for authorization and funding. Construction would begin after that.

Given that the Corps would be narrowing down the alternatives to two by late fall, it wasn’t clear how the environmental analysis for all the alternatives could possibly be done within just a few months, as outlined by Corps biologist and senior planner Daria Mazey, so as ensure the plans with the least damage to the environment would be selected.

While Mazey said the Corps would be looking at all the environmental considerations, such as changes to tidal range, flow velocity, salinity concentrations, sedimentation rates, water quality, and dissolved oxygen — Wisemiller said the final report had to be “environmentally acceptable” as well as “economically justified,” meaning the monetary benefits would outweigh the dollars spent. The environment does not figure in the final cost-benefit analysis, according to Peter Weppler, chief of the Corps’ environmental analysis branch. “In the Corps world, we do not put a dollar value on ecosystems,” he said. “We can talk about it qualitatively, but it’s not attributed within our calibration yet. When we do ecosystem restoration, it’s a non-monetary calculation.”


Another concern brought up in the Q&A session was the need to address the problem of climate change first, rather than focus on its effects. “This study addresses severe risk. We fold in sea-level rise, but how climate change affects the weather is not scientifically established yet,” responded Wisemiller. Mazey said that given that “the amount of carbon already released will be affecting us for at least a decade if not more even if we stop emitting carbon now, we need to do both, stop emissions and deal with and adapt to the new changed environment.”

But Lipscomb said a key problem is that “the Army Corps is studying only mitigation measures for storm surge. They’re not studying how to protect the city and the communities on the tidewater from sea level rise. It’s not rational, to be considering projects of such enormous cost that address one problem and not the other, when options exist that will protect against both. … In the fall they will winnow [the plans] down to one or two. Why is it the Army Corps can select the final one or two alternatives with less environmental review than building a 100-slip marina?”

Matthew Chlebus, a DEC environmental engineer, was briefly introduced at the meeting. Questions subsequently posed to Chlebus in a call by this reporter were answered by email by DEC spokesperson Erika Ringewald. Asked to confirm Wisemiller’s statement that the DEC has the power to end an alternative plan within 30 days, Ringewald sidestepped the question, responding that the DEC “is working collaboratively with the Army Corps and a wide range of stakeholders to develop and scientifically vet options to improve coastal resiliency.” She confirmed that “New York’s approval is necessary before any resulting project proposal can be undertaken within New York.” Suggesting that it is premature to weigh in on any of the proposals, given the paucity of information, she added that “the full range of necessary regulatory approvals is dependent on the specific project proposal, which is not known at this time.”

The tight frame imposed by the Army Corps on narrowing down the options is apparently not a factor in the DEC’s review, she further suggested. “DEC is committed to working with the Army Corps and stakeholders so that all reasonable options are understood, discussed, and assessed prior to limiting the scope of the study,” she wrote.

Lipscomb said existing studies document the detrimental effects of restricting the tidal exchange in harbors and tidal portions of rivers. “Any of these projects which include barriers to block natural flow of water is damaging to the Hudson ecosystem and other river bodies, and we cannot accept that,” he said, adding, “Riverkeeper does not recommend doing nothing. We’re suggesting that we build the shoreline measures now. They’re saying it wouldn’t be until 2032 that anything would be in place. That’s 14 hurricane seasons from now,” which means those dykes, levies and floodwalls would likely significantly reduce the risk of storm-surge damage. Building the shorelines measures would also cost a fraction of construction of the barriers, and the construction would be incremental, so that the “most at-risk areas would be addressed first. Meanwhile we can search for more resources” for building others in outlying areas.”

The flood-prevention measures that are currently being built in the city “aren’t just big concrete walls 20 feet high,” he added. He described one such project along the lower East Side waterfront of Manhattan as “a grassy knoll along the shoreline. It’s a park, which can be used by the public, and it also protects against sea level rise.”

While the Corps representatives said public input was critical to identifying the issues of concern, Riverkeeper and other environmental organizations are raising questions about the transparency of the process. The Corps gave only 15 days’ advance notice of each meeting, and “the broadcast was very limited,” according to Lipscomb.

“Ninety-five percent of the people in the room” at the Poughkeepsie meeting “had heard about it from Riverkeeper. Why is that?” said Lipscomb. “An organization with two communications staff get to do better than the Army Corps in communicating the location and date. Why was there one meeting for the entire 150-mile-long Hudson and all the communities that line it? Why didn’t the DEC post these meetings on their website?”

“We’ll be working with existing data regarding our research,” Wisemiller said. Mazey added that “we’re looking to the local communities as keepers of valuable local knowledge.”

Lipscomb also said information from Corps on their plans was lacking in some aspects. For example, there was nothing on how big the openings of the five-mile-long barrier will be, or the number of openings. “There was no data whatsoever — nothing on how the barriers will affect the fish,” he said.

“Riverkeeper is just beginning our research into massive existing in-river barriers, such as the one of the Thames and at St. Petersburg, Rotterdam and others in Holland,” he said. “We asked the Army Corps for any studies they have of these large massive in-water barriers and they are reviewing them. We asked for the studies and were told we could not have them. … If you’re going to consider such monumental projects that have forever consequences, you have to do better than just rely on whatever happens to be published.”

For more information on the Army Corps of Feasibility Study, and to make a comment, visit and submit a comment through the contact link with subject “Scoping Input.” You can also access Riverkeeper’s July 5 blog post on the study, 

There is one comment

  1. nar ar nar

    “Ninety-five percent of the people in the room” at the Poughkeepsie meeting “had heard about it from Riverkeeper. Why is that?” said Lipscomb. “An organization with two communications staff get to do better than the Army Corps in communicating the location and date. Why was there one meeting for the entire 150-mile-long Hudson and all the communities that line it? Why didn’t the DEC post these meetings on their website?”

    Umm, because you sent out an email to your list of local environmentalists, and they’re the most likely to attend a public meeting on this subject? Do you really think many folks across this region are checking out the DEC or Army Corps. websites for upcoming meetings?

    Also, the announcement of these meetings was covered in local media. But there it competes with all manner of other stories and may not reach the environmentally inclined reader.

    But yeah, one person, armed with an email list for an interest group, is how most people find out about meetings. Welcome to political communications 101!

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