Flooding in Closter, New Jersey: the flood zone, the record, and what to do
Closter sits where water coming off the highest part of the Palisades meets the Oradell Reservoir. Two brooks cross the borough on the way, and one of them has a USGS stream gauge with a record going back to the 1960s.
The Bergen County 2026 Hazard Mitigation Plan puts 19.65 per cent of Closter in the 1 per cent annual chance flood zone. FEMA's National Flood Insurance Program has recorded 47 flood claims in the borough and lists seven repetitive-loss properties. The Tenakill Brook and the Dwars Kill both cross Closter before reaching the Oradell Reservoir, and the borough itself names flash flooding as its most significant natural hazard.
The short version
- The Bergen County 2026 Hazard Mitigation Plan maps 19.65 per cent of Closter in the 1 per cent annual chance flood zone.
- FEMA records 47 NFIP flood claims in Closter, 11 of them in 2021, and seven repetitive-loss properties.
- The USGS Tenakill Brook gauge at Closter peaked at 1,500 cubic feet per second in April 2007, above FEMA's 2 per cent estimate.
- The Dwars Kill rises in Alpine and crosses Closter to the Oradell Reservoir; the borough has worked on it at Colgate and Ruckman Road.
- Closter names flash flooding as its most significant natural hazard in the county plan.
Nearly a fifth of the borough is mapped
Table 4.6-1 of the Bergen County 2026 Hazard Mitigation Plan counts about 415 acres of Closter in FEMA's Special Flood Hazard Area, 19.65 per cent of its 2,110 acres. Including the 0.2 per cent annual chance zone, the share is 21.84 per cent. Not all of that is land where people live. The US Census Bureau records about 0.14 square miles of water inside the borough, roughly 90 acres, and FEMA's Flood Insurance Study lists Closter among the boroughs bordering the Oradell Reservoir, whose 1 per cent annual chance level it sets at 25.7 feet. By our arithmetic, the reservoir and its fringe could account for a fair part of the mapped area. The rest follows the two brooks.
The record
FEMA's OpenFEMA data show 47 NFIP claims in the Borough of Closter over the life of the programme. The worst year was 2021, with 11 claims, nine of them attributed to Hurricane Ida. Hurricane Floyd in 1999 and Irene in 2011 each produced six claims in their years, and 2007 produced four. FEMA's multiple-loss records, as of 2 August 2026, list seven Closter repetitive-loss properties, one of them in the severe repetitive loss category. The county plan reports 24 active NFIP policies as of October 2024, out of 2,834 housing units counted by the US Census Bureau. Very few households, in other words, are insured against the flooding the map describes, which means the claim count understates how many homes have actually taken water.
The Tenakill Brook gauge
USGS has measured the Tenakill Brook at Closter since the 1960s, at a point where it drains about 8.6 square miles. Its largest annual peaks are 1,500 cubic feet per second on 15 April 2007, at a gauge height of 7.20 feet; 1,350 on 2 September 2021, during Ida; 1,300 on 16 September 1999, during Floyd; and 1,150 on 28 August 2011, during Irene. FEMA's flood study estimates the 2 per cent annual chance flow where the brook enters the reservoir at about 1,420 cubic feet per second and the 1 per cent flow at 1,700. The April 2007 nor'easter therefore exceeded FEMA's fifty-year estimate, and Ida came close. There is no National Weather Service forecast point on the brook, so the USGS readings are a record rather than a warning.
The Dwars Kill and the feeder brooks
The Dwars Kill begins in Alpine, where USGS has a gauging point at Anderson Avenue draining barely a third of a square mile, and crosses Closter and Norwood to the Oradell Reservoir. By the reservoir FEMA puts its drainage area at 3.6 square miles. FEMA's study notes that the Palisades reach their highest point in Bergen County, about 550 feet, at Closter, so water arriving from the east comes down a steep slope fast. The Northern Valley Press reported in February 2026 that the borough has worked on the Dwars Kill at Colgate and Ruckman Road, on Anderson Brook at Meadow Lane and Homans Avenue, and on drainage at Hickory Lane, cleaning brooks and stabilising banks, and that a 2024 ordinance raised required drain sizes for certain construction from 2 to 3 inches.
Flash flooding as the main hazard
In its summary for the county plan, Closter describes flash flooding as having proven the most significant risk to the community, and commits to improving the resilience of its feeder stream systems with the State. That is consistent with the gauge record and the claim pattern: short, intense storms like Ida, falling on a steep eastern slope and a developed valley floor, send water into small brooks faster than their culverts can pass it. The US Census Bureau puts the median year built of Closter homes at 1959, so many basements predate modern drainage and sump requirements. In a flash flood, the water that reaches a basement can come through a window well, a wall joint or a floor drain as easily as across the yard.
What this means if you own or rent here
Check your address on the FEMA Flood Map Service Center. If you live near the Tenakill, the Dwars Kill or Anderson Brook, the April 2007 and Ida peaks are the benchmarks to plan around. Keep culvert mouths and yard drains clear before heavy rain, keep valuables off basement floors, and make sure your sump pump has a backup. Flood insurance is a separate policy from homeowners insurance, and FEMA states that a new policy normally takes 30 days to take effect. About 18 per cent of Closter homes are rented, according to the Census Bureau, and a landlord's policy does not cover a tenant's belongings. Sewer backup and groundwater seepage are treated differently from flood; whether a given loss is covered is decided by your insurer and your policy wording.
Common questions
Does Closter, NJ flood?
Yes, mainly in flash floods along its brooks. FEMA counts 47 flood insurance claims in Closter, with the most in 2021 from Ida, and the county plan maps about a fifth of the borough in the 1 per cent annual chance flood zone, some of it along the Oradell Reservoir.
Which streams flood in Closter?
The Tenakill Brook and the Dwars Kill are the two main streams in FEMA's flood study, with smaller feeders such as Anderson Brook. Both main brooks drain to the Oradell Reservoir. For a specific address, use the FEMA Flood Map Service Center.
Is there a flood gauge for Closter?
USGS operates a gauge on the Tenakill Brook at Closter, which recorded its largest peak in April 2007 and its second largest during Ida. It has no National Weather Service flood forecast, so use local alerts and the weather forecast as your warning.
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