What Hurricane Ida did to Bergen County: the rain, the rivers and the record
On the evening of September 1, 2021, the remnants of Hurricane Ida brought some of the most intense rainfall ever measured in northern New Jersey. In Bergen County the damage came less from the rivers than from rain that fell faster than streets, drains and basements could take it.
The remnants of Ida crossed New Jersey on September 1 and 2, 2021. Gauges in Bergen County recorded between about seven and nine inches of rain, and at Lyndhurst the three-hour total was rated by the state climate office as a once-in-1,000-years event. Rivers rose, but the Saddle River at Lodi and Pascack Brook at Westwood each recorded their fourth-highest crest or peak rather than a record. FEMA declared a major disaster on September 5, 2021, and Bergen County was designated for individual assistance. This guide sets out what the National Weather Service, the US Geological Survey, FEMA, the Office of the New Jersey State Climatologist and the county hazard plan record, and where they are silent.
The short version
- The highest two-day rainfall recorded in Bergen County during Ida was 9.02 inches at North Arlington.
- Lyndhurst recorded 5.85 inches over three hours, rated by the state climate office as a 1,000-year event.
- The Saddle River at Lodi crested at 12.57 feet on September 2, 2021, its fourth-highest crest; Pascack Brook at Westwood recorded its fourth-highest peak flow.
- The county hazard plan describes widespread flash flooding, road closures and water rescues, and lists basement flooding and sewer infiltration among Ida's effects.
- FEMA declared a major disaster, DR-4614, on September 5, 2021, and designated Bergen County for individual assistance.
- About 30 people died in New Jersey as a result of Ida flash flooding; the sources do not give a Bergen County figure.
How much rain fell, and how fast
The Office of the New Jersey State Climatologist at Rutgers published the most detailed account of the rainfall. Its highest two-day total in Bergen County was 9.02 inches at North Arlington, and it placed Bergen among eight counties with at least one station above eight inches. The striking figures are the short-duration ones. At Lyndhurst, 3.58 inches fell over one hour ending at 9.30 pm, 4.88 inches over two hours and 5.85 inches over three hours ending at 9.55 pm. The climate office rated the one-hour and two-hour totals as 500-year events and the three-hour total as a 1,000-year event, which means rainfall that intense has roughly a one in 1,000 chance of occurring at that spot in any given year. At Haworth, in the north-east of the county, 3.10 inches fell over one hour and 4.98 inches over three hours, rated as 200-year and 500-year events. Rain was not even across the county: at Ramsey the one-hour figure was 2.26 inches, rated a 25-year event. The Bergen County hazard plan records 7.14 inches at Teterboro Airport and 8.44 inches at Newark Airport, and describes totals of five to more than eight inches across much of the region, much of it falling over a short period during the evening of September 1.
A flash flood more than a river flood
Most of the harm in Bergen County came from that intensity. The county hazard plan describes widespread flash flooding, numerous road closures and water rescues, in addition to extensive river flooding. Elsewhere it lists Ida among the storms that have caused widespread basement flooding, roadway washouts, damage to building foundations and infiltration of sewer systems, and it names Hackensack, Ridgewood, Lodi, Little Ferry, Moonachie and Fair Lawn as urban centres that often experience flash flooding because of ageing or undersized stormwater systems and a high share of paved surface. That pattern matters for anyone who assumes their risk depends only on distance from a river. When rain falls at three or more inches an hour, the limit is how much water storm drains, sewers and the ground around a foundation can carry away, and that limit is reached far from any mapped floodplain.
What the rivers did
The rivers rose sharply but, on the gauges opened for this guide, did not set records. The National Weather Service lists a crest of 12.57 feet on the Saddle River at Lodi on September 2, 2021, more than four and a half feet above the 8.0-foot major flood stage and the fourth-highest crest on its list, behind Floyd in 1999, Irene in 2011 and April 2007. US Geological Survey records for Pascack Brook at Westwood show a peak of 2,980 cubic feet per second and a gauge height of 7.42 feet on September 2, 2021, the fourth-highest annual peak flow since records began in 1934. The record there, in September 1999, is flagged by the USGS as affected by a dam failure. The National Weather Service crest list for the Hackensack River at New Milford, which is regulated by the reservoirs upstream, does not include an Ida crest; its highest is 12.36 feet in April 2007. Its list for the Saddle River at Ridgewood shows only one crest, from 2011. This guide does not read anything into those gaps beyond what they say: the published lists do not record an Ida crest at those sites. Across northern New Jersey as a whole, the USGS reported two days after the storm that eight of its streamgages had recorded peaks higher than any in their records and that six gauges had been damaged by floodwater.
Loss of life
The Office of the New Jersey State Climatologist records that about 30 people died in New Jersey as a result of Ida flash flooding, most of them drowning in or near vehicles or homes, and that this was the second-greatest loss of life from a natural event in the state in at least a century, after Sandy in 2012. The Bergen County hazard plan quotes an event description for the wider north-east New Jersey region that records eight deaths from the flash flooding and one person missing, while the plan's own table records no deaths or injuries in its Bergen County rows for the event. The plan does not reconcile those two entries, and none of the sources opened for this guide gives a count of deaths in Bergen County alone.
The disaster declaration
The federal response is recorded in two declarations. The county hazard plan lists an emergency declaration, EM-3573, on September 2, 2021, followed by a major disaster declaration, DR-4614, on September 5, 2021, both for the remnants of Hurricane Ida. FEMA gives the incident period as September 1 to September 3, 2021, and lists Bergen County among the counties designated for individual assistance, the programme that provides help directly to households. Across New Jersey, FEMA reports 43,792 approved individual assistance applications under DR-4614. FEMA does not break that figure down by county on the declaration page. The hazard plan notes that Ida was one of three federal disaster declarations for Bergen County since its previous plan, alongside COVID-19 and Tropical Storm Isaias.
What was measured afterwards
Much of what is known about how high the water rose comes from fieldwork done after the storm. Under an assignment from FEMA, the US Geological Survey surveyed 139 high-water marks at 50 sites in flood-affected parts of New Jersey between September 8 and September 30, 2021, and published them as a public data release in November 2021. Ridgewood is among the communities in that survey. The data release is the place to look for surveyed water levels at specific sites; this guide does not reproduce individual marks. The county hazard plan, approved in 2026, treats Ida as part of a pattern rather than a one-off. It records that repetitive flooding of the kind seen during Irene in 2011 and Ida in 2021 has raised insurance premiums, added restrictions on building in floodplains and reduced property values in affected areas, and it expects storms of this kind to become more frequent.
What Ida means if you own or rent here
Three lessons stand out from the record. First, a mapped flood zone does not describe flash-flood risk. Ida did much of its damage through basements and streets that filled because rain arrived faster than drains could carry it, which is a risk in every town in the county. Whether a particular address is in a mapped flood zone is a question for the FEMA Flood Map Service Center, but a basement anywhere can take water in a storm like this. Second, the useful preparation is done in advance: nothing valuable stored on a basement floor, a clear plan for where the car goes, and knowing how to switch off the power before water reaches outlets or the panel. Third, flood insurance is a separate policy from homeowners insurance, and FEMA states that a new flood policy normally takes effect 30 days after purchase, so it cannot be arranged once a storm is forecast. Most of the deaths recorded statewide during Ida were of people in or near vehicles. Never walk or drive into floodwater, treat standing water indoors as an electrical hazard until the power is confirmed off, and assume water that has come up through drains or a sewer connection may be contaminated with sewage.
Common questions
How much rain did Ida drop on Bergen County?
The Office of the New Jersey State Climatologist records a two-day total of 9.02 inches at North Arlington, the highest in the county, and the Bergen County hazard plan records 7.14 inches at Teterboro Airport. Totals varied across the county, and the most intense rain fell over a few hours on the evening of September 1, 2021.
Did the rivers in Bergen County set records during Ida?
Not on the gauges opened for this guide. The Saddle River at Lodi crested at 12.57 feet, its fourth-highest crest, and Pascack Brook at Westwood recorded its fourth-highest peak flow since 1934. The published crest lists for the Hackensack River at New Milford and the Saddle River at Ridgewood do not include an Ida crest.
Was Bergen County included in the Ida disaster declaration?
Yes. FEMA lists Bergen County among the counties designated for individual assistance under major disaster declaration DR-4614, declared on September 5, 2021, for an incident period of September 1 to September 3, 2021.
Why did homes far from rivers flood during Ida?
Because the rain fell faster than drainage could carry it. At Lyndhurst 3.58 inches fell over a single hour. The county hazard plan links flash flooding in towns such as Hackensack, Ridgewood, Lodi and Fair Lawn to ageing or undersized stormwater systems and a high share of paved surface, and records basement flooding and sewer infiltration as effects of Ida.
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