How Do North Jersey's Flood Defenses Work?

Bergen County is trapped between two distinct flooding threats. From inland, heavy rains overwhelm local rivers like the Passaic, Hackensack, and Saddle Rivers, a problem made worse by increasingly paved inland ground that can no longer absorb the runoff. From the coast, a storm's low pressure and onshore winds drive a surge of seawater backward, pushing it up those same rivers. While most storms bring only one of these threats, the most dangerous storms bring both at once.

Engineers call this phenomenon "compound flooding." Compound flooding occurs when a river already swollen with rain collides with a storm surge pushing the other way, leaving the combined water with nowhere to go.

Lessons from Ida and Sandy

Hurricane Ida, in September 2021, was the "riverine" (caused by river overflow) version. During this storm, the Hackensack, Saddle, and Passaic Rivers all crossed their flood stages, the level at which a river spills over its banks, simultaneously. As a result, we saw the worst inland flooding in modern Bergen County history.

Superstorm Sandy, in 2012, was the coastal version of flooding. Sandy damaged more than 300 rail cars and locomotives at NJ Transit's Meadowlands maintenance complex and Hoboken rail yard, costing over $400 million. It also destroyed electrical substations along the Hudson County and North Jersey waterfront, and flooded major hubs like Hoboken Terminal and the Frank R. Lautenberg Station in Secaucus.

Together, these two storms show why North Jersey needs defenses against water coming from both directions, and why a defense built for one threat can easily fail against the other.

What Keeps North Jersey Dry Today

Today's physical defenses are a mix of hard structures and natural storage, much of which is decades old. Raised levees and floodwalls line stretches of the Passaic, Hackensack, and Saddle Rivers to keep rising channels from spilling into developed neighborhoods. The Army Corps of Engineers has built several smaller flood-control projects along the Pompton, Ramapo, and Saddle Rivers, as well as along Molly Ann Brook, a smaller Passaic tributary. A new project for Peckman Brook, a tributary running through Essex and Passaic Counties, is currently being considered. However, none of these projects offer a basin-wide solution. They protect specific, isolated stretches rather than the combined Passaic-Hackensack-Saddle watershed as a whole.

The largest piece of natural flood storage in North Jersey is the Hackensack Meadowlands, a 30-square-mile wetland complex in southeastern Bergen County that acts as a natural sponge, soaking up floodwater before it can reach homes and businesses. Unfortunately, this capacity has been shrinking for decades as rail yards, warehouses, highways, and airports, including Teterboro, have been built on ground that once held water.

Upstream, the Oradell Reservoir holds back the upper Hackensack River to secure Bergen County's drinking water, which creates a direct conflict between water supply and flood control. A reservoir kept full to guarantee drinking water has less empty space to absorb sudden storm runoff, while a reservoir lowered to catch floodwater risks running low during a drought. No regional rule or design standard currently decides which of these competing needs should take priority.

Eyes on the Water

A layer of monitoring sits on top of these physical defenses. The Army Corps' Passaic River Flood Warning System covers the 935-square-mile Passaic Basin, an area home to roughly 2.5 million people across 132 communities spanning nine counties in New Jersey and New York, including Bergen, Passaic, and Essex. Alongside this, the Meadowlands Research and Restoration Institute runs a continuous water-level sensor network on the Hackensack River. This network sends automatic alerts when water reaches specific heights. A height of 4.75 feet triggers a general warning, while 7 feet is the threshold the district treats as a serious flooding event.

The Missing Tunnel

The most direct engineering solution to flooding across the Passaic Basin has existed on paper since the early 1900s, but it has never been built. This proposal is a "diversion tunnel," essentially a massive underground channel designed to carry floodwater around local towns and straight out to Newark Bay. The planned tunnel would be roughly 20 miles long and 40 feet in diameter, starting where the Pequannock, Wanaque, Ramapo, and Pompton Rivers meet the Passaic near Wayne, the most flood-prone point in the basin. A flood warning and forecasting system would signal when to open it.

Although the idea originated with a federally appointed commission active between 1902 and 1936, and took its current form in the mid-1980s, it has never moved past the planning phase. The Army Corps evaluates projects by comparing construction costs against the dollar value of damage prevented, and by that standard, the tunnel at full scale has never shown enough prevented damage to justify its massive price tag. Even a scaled-back version designed to protect only the most frequently flooded areas failed to move forward.

The Corps also cannot proceed without a formal request from New Jersey as the project's non-federal sponsor (the state or local partner required to request a federal project and help fund it); the state has never made that request. Meanwhile, at least 26 lives have been lost to Passaic River flooding since 1900.

The Army Corps' New York District continues to re-evaluate alternatives for the Passaic Basin. Its most recent study, completed in 2019, narrowed the options down to three choices: building the tunnel, constructing a network of levees and floodwalls, or taking a non-structural approach. This third option involves no new construction, focusing instead on buying out flood-prone properties and raising homes above flood level. Only the buyout option has moved forward at any real pace.

New Jersey's Blue Acres program continues to purchase and demolish repetitively flooded properties in the basin rather than funding major infrastructure. The Passaic River Coalition, which has worked on this issue since 1969, argues that no large project will ever be quick or cheap, and that flood damage will keep recurring as long as the basin continues to be studied rather than built.

The Fight Over Coastal Barriers

To address the coastal threat, the Army Corps has been conducting the New York-New Jersey Harbor and Tributaries Study, known as HATS. Alongside New York, New Jersey, and New York City, the Corps has evaluated storm surge barriers and shoreline options across a 2,150-square-mile study area spanning 25 counties across the greater New York City metropolitan region since 2016. In August 2022, the Corps selected a preferred design called Alternative 3B. This $52.7 billion plan proposes twelve storm surge gates across major waterways and more than 41 miles of shoreline seawalls and floodwalls, with a construction timeline of 14 years. One of these proposed gates would sit on the Raritan River.

These movable gates would stay open under normal tidal and shipping conditions, closing only when a storm surge approaches, meaning they would have almost no effect on the Hudson-Raritan Estuary most of the time. Using a standard 50-year projection period that federal agencies use to weigh a project's cost against the damage it prevents, the Corps estimated the plan could reduce coastal storm damages by an average of $6.2 billion a year between 2044 and 2093.

Despite these projections, the plan has faced serious environmental and technical objections. Groups like Riverkeeper warned that closing the gates during a storm could trap rainwater runoff, raw sewage, and heavy pollution behind the barriers, flooding the very neighborhoods they were built to protect. This risk is especially high because three of the affected waterways are active federal Superfund cleanup sites. The Regional Plan Association, an independent urban planning nonprofit that studies the tri-state area, also questioned how often the gates would need to close and which state agency has the authority to order a closure during a dispute.

Separately, the Waterfront Alliance pushed for a phased approach that relies more heavily on natural defenses.

The scope of the HATS plan shifted dramatically in late 2023. New York's Department of Environmental Conservation, acting as the study's non-federal sponsor, sent a letter refusing to accept any plan designed around storm surge alone. The department demanded that the design also account for sea-level rise, rising groundwater tables that push up from below, and heavy rainfall. That demand forced a required re-study under federal water law, leaving the comprehensive $52.7 billion plan unfunded. Instead, the Corps has identified a shorter list of near-term, localized projects called Actionable Elements, aiming for Congressional authorization of a first batch in a Water Resources Development Act expected in 2026, with additional elements potentially following in a 2028 bill.

Working with Nature

Not every flood project in North Jersey relies on heavy gates or concrete tunnels. Off Staten Island's south shore, in Raritan Bay, a completed $111 million project called Living Breakwaters uses partly submerged stone structures to break wave energy and slow shoreline erosion before waves can crash into the coast. Designed by SCAPE Landscape Architecture through the Rebuild by Design competition, these breakwater units are made of an ecologically enhanced concrete developed with the firm ECOncrete. This material is roughly 92 percent carbon-neutral and features an engineered, textured surface designed to help oysters and other marine life colonize the structures. The Billion Oyster Project supplied the habitat-restoration elements.

By using this design, the team reported an 80 percent reduction in environmental mitigation penalties, the regulatory costs assessed when a project damages habitat, compared to traditional concrete armor units.

This "living shoreline" approach uses marshes, reefs, and vegetation to absorb storm energy rather than blocking it outright. Stevens Institute of Technology's Davidson Laboratory has done direct modeling work to support this method: researcher Reza Marsooli has built three-dimensional hydrodynamic models of hybrid systems that combine a physical seawall with planted marsh vegetation. His research quantifies exactly how much coastal wetlands reduce incoming storm tides, giving engineers the data they need to design and size a living shoreline with the same precision they would use for a concrete wall.

Rebuilding the Meadowlands

Several projects addressing chronic flooding in the Meadowlands are already under construction. Funded with $150 million in post-Sandy federal disaster money and engineered by AECOM for the state environmental agency, the New Meadowlands project treats the area as a single connected watershed rather than defending each town individually. Its components include the East Riser Ditch pump station and channel improvements and the Liberty Street pump station and force main, a pressurized pipe that pushes water uphill where gravity alone can't drain it, along with green infrastructure and open-space work spread across Little Ferry, Teterboro, Moonachie, South Hackensack, and Carlstadt, with most elements scheduled for substantial completion by September 2025.

This project addresses a highly documented gap: per Rebuild by Design's own project documentation, the Meadowlands' municipal sewers cannot handle heavy rainwater even outside of major storms, making street flooding in these towns a chronic nuisance rather than an occasional emergency.

New Jersey's Resilient NJ program is funding a broader planning layer behind these individual projects, including an updated Meadowlands Strategic Plan and new flood maps, financed in part by a $72 million NOAA grant under the state's Building a Climate Ready NJ initiative. A new Resilient NJ regional planning grant cycle opened in April 2026 and closes July 7, 2026, meaning Bergen County municipalities are deciding whether to apply right now, as this is published.

However, an independent evaluation by Rutgers University's Edward J. Bloustein School, conducted with an NSF-funded research partnership, concluded that the Meadowlands' current planning efforts remain fragmented. The 2023 studio found that the state's own Meadowlands master plan, Rebuild by Design projects, and county hazard mitigation plans do not yet add up to a cohesive, region-wide resilience framework.

Hardening the Transit Network

In transit, the severe damage from Superstorm Sandy forced agencies to redesign their infrastructure. The storm flooded about 150 subway stations and caused roughly $5 billion in damage. Since then, the MTA has installed about 4,000 physical surge protections, barriers like flood doors and vent covers, including heavy watertight marine doors at the Hugh L. Carey and Queens Midtown tunnels. To prioritize this massive task, a 2025 research project by NYU Tandon's Yuki Miura built a computer model to test hundreds of flood scenarios, helping the agency decide which of its roughly 3,500 system openings to seal first.

The MTA's 2025-2029 Capital Plan dedicates roughly $700 million specifically to subway stormwater flood mitigation, part of more than $1.5 billion in resilience funding against a roughly $6 billion decade-long need. That funding covers raising subway entrances, elevating street-level vents, and upgrading pump rooms, about 11 percent of which were in marginal or poor condition as of 2023.

This transit effort highlights a governance limit that engineering cannot fix. Many of the subway's most vulnerable points sit at street level, which the MTA does not control. On some sidewalks, curbs are as low as 2.5 inches, allowing ordinary rainwater to pour straight into the subway vents, and fixing that is New York City's Department of Transportation's job, not the MTA's. Keeping catch basins clear and sewer capacity available during a storm is NYC DEP's job. Eric Wilson, the MTA's senior vice president for climate and land use strategy, runs an interagency stormwater task force with DOT and DEP that conducts joint site visits to work out which agency is actually responsible for a given fix, and the MTA's 2025 Climate Resilience Roadmap update names ten priority locations across New York City where the agency says the missing action is the city's, not its own.

NJ Transit took a different approach after Sandy, combining system hardening with relocation. While some assets were elevated and protected in place, like the Bay Head substation, other major projects were moved entirely. In 2024, the agency canceled a long-planned, environmentally contested microgrid, a small gas-fired power plant meant to keep trains running if the main grid failed, that had been proposed for the Meadowlands, and redirected more than $500 million toward other projects. These include replacing the Raritan River rail bridge and building a new $497 million flood-protected rail yard and inspection facility outside of the flood zone near New Brunswick, which broke ground in late 2024.

Moving critical equipment out of a floodplain entirely is a rare choice in regional planning, especially given how much of North Jersey's utility and transit infrastructure remains in vulnerable locations by default.

An Environment Changing Faster Than Infrastructure

Two major climate trends are now worsening faster than local infrastructure can adapt. Rising sea levels continuously elevate the baseline for coastal flooding, meaning even minor storm surges cause worse damage over time. At the same time, rainfall is becoming much more intense, and most of North Jersey's drainage infrastructure was sized using historical records that assumed the future would look like the past. That mismatch is what's driving NOAA's ongoing replacement of its rainfall dataset, Atlas 14, with an updated version, Atlas 15, that builds in climate forecasting rather than relying on historical averages alone.

The underlying challenge is the multi-hazard gap that New York's DEC flagged in its 2023 letter: surge barriers designed to block ocean water can trap rain-driven flooding on the landward side of a closed gate, the same issue running through the Passaic tunnel's history and the Meadowlands' sewer backup problems. No single engineered structure spanning the Passaic Basin, the Meadowlands, and the Hudson-Raritan Estuary is designed to handle coastal surge, river flooding, and heavy rainfall as one combined hazard; reservoirs, levees, tunnels, and gates were each built to solve only one piece of the puzzle.

Concrete Versus Nature

That patchwork of single-purpose defenses leaves a persistent tension between hard engineering and natural alternatives. Hard structures like gates, tunnels, and floodwalls protect specific assets directly, but they are expensive, slow to build, and can push floodwaters into neighboring areas. Soft approaches like property buyouts and wetland restoration, including living shorelines like Living Breakwaters, cost less and adapt more naturally to rising seas, but they require accepting that some low-lying stretches of the Meadowlands and the Passaic Basin simply cannot be defended. Ultimately, North Jersey is not held back by missing engineering.

Your Takeaway

Designs for the Passaic tunnel, the HATS surge gates, and living shorelines already exist. What's unresolved is which of these plans will receive the funding and political will to be built, and which will remain on paper while the water continues to rise.