Flooding in Harrington Park, New Jersey: the flood zone, the record, and what to do
By share of area, Harrington Park has one of the largest mapped flood zones in the Northern Valley. By FEMA's claim count it is one of the quieter boroughs. Both are true, and the Oradell Reservoir is most of the reason.
The Bergen County 2026 Hazard Mitigation Plan puts 23.73 per cent of Harrington Park in the 1 per cent annual chance flood zone. FEMA's National Flood Insurance Program has recorded 18 flood claims in the borough over the life of the programme and lists two repetitive-loss properties. The mapped zone covers the borough's share of the Oradell Reservoir and the valley of Dorotockey's Run, a brook that enters the reservoir at Harrington Avenue.
The short version
- The Bergen County 2026 Hazard Mitigation Plan maps 23.73 per cent of Harrington Park in the 1 per cent annual chance flood zone.
- FEMA records only 18 NFIP flood claims in the borough and two repetitive-loss properties, as of August 2026.
- By the Census Bureau's water area, the Oradell Reservoir itself could be close to half of the mapped zone.
- Dorotockey's Run enters the reservoir at Harrington Avenue, and FEMA notes its lower reach floods when the reservoir is high.
A big zone, a short record
Table 4.6-1 of the county plan counts about 313 acres of Harrington Park in FEMA's Special Flood Hazard Area, 23.73 per cent of 1,319 acres, or 25.17 per cent with the 0.2 per cent annual chance zone added. That is one of the larger shares in the county. Against it, FEMA's OpenFEMA data show 18 NFIP claims in total. The busiest year was 2021, with four; 1999 had three, and 2011 and 2012 two each. By named event, Hurricane Ida and Hurricane Floyd are each linked to three claims, Irene and Sandy to two. FEMA's multiple-loss records, as of 2 August 2026, list two repetitive-loss properties and none in the severe category. The county plan reports 19 active NFIP policies as of October 2024, for 1,818 housing units counted by the US Census Bureau.
How much of the zone is water
The Census Bureau records 0.217 square miles of water in Harrington Park, about 139 acres, nearly all of it the Oradell Reservoir. The county plan's total area for the borough matches its land and water combined, so by our arithmetic the reservoir surface could account for close to half of the mapped flood zone. Take the water out and the flood zone covers something nearer one-seventh of the borough's dry land, concentrated along the reservoir shore and the brooks running into it. That goes a long way to explaining why so large a mapped share has produced so few claims. The County Route 502 bridge on Old Hook Road, the only road crossing of the reservoir, links the borough to Closter across that water.
Dorotockey's Run and Tappan Run
FEMA's Flood Insurance Study follows Dorotockey's Run down from Old Tappan into Harrington Park and on to the reservoir. At Harrington Avenue, where it meets the reservoir, the study puts its drainage area at 4.28 square miles and its 1 per cent annual chance flow at about 990 cubic feet per second. Other points the study names on the brook include Swim Club Drive, Blanch Avenue and First Street. Tappan Run, a smaller tributary, is studied separately within the borough and joins Dorotockey's Run. FEMA notes a particular feature of this brook: its lower reach floods when the Oradell Reservoir is high, because the reservoir backs water up the channel. A storm that fills the reservoir and the brook at the same time is therefore the one most likely to spread water widely.
When the reservoir is high
The study gives the Oradell Reservoir a spillway crest of 22.7 feet and a record stage of 26.2 feet on 17 September 1999, after Floyd, against a previous record of 25.0. FEMA's 1 per cent annual chance level for the reservoir, which it lists for Harrington Park among six shoreline boroughs, is 25.7 feet. That 1999 event is reflected in the claim record, with three Harrington Park claims tied to Floyd. Sandy, by contrast, brought less than 2 inches of rain to Bergen County according to the FEMA study; the claim data do not record what caused the two Sandy claims here.
Basements and the borough's plans
The Census Bureau puts the median year built of Harrington Park homes at 1962, and fewer than 8 per cent are rented. For the large majority of households away from the reservoir and Dorotockey's Run, the realistic water risks are groundwater seepage after long rain, a stopped sump pump and failed plumbing, none of which counts as flood. In its summary for the county plan, the borough says it has focused on increasing flood resilience and upgrading essential infrastructure, reporting one completed and eleven ongoing actions.
What this means if you own or rent here
Check your address on the FEMA Flood Map Service Center, paying attention to whether you are near the reservoir shore or the Dorotockey's Run valley, where reservoir backwater and brook flooding can combine. If you are, a flood policy is worth pricing; FEMA states that a new one normally takes 30 days to take effect. If you are elsewhere in the borough, put the effort into the house: a tested sump pump with backup power, downspouts discharging away from the walls, and nothing valuable stored on the basement floor. A tenant's belongings are not covered by the landlord's policy. Seepage and sewer backup are handled differently from flood, and whether a given loss is covered is decided by your insurer and your policy wording.
Common questions
Does Harrington Park, NJ flood?
In limited areas. FEMA counts 18 flood insurance claims in total. The mapped flood zone is large, about a quarter of the borough, but much of it is the Oradell Reservoir itself and the valley of Dorotockey's Run.
Which parts of Harrington Park are most at risk?
Land along the Oradell Reservoir shore and along Dorotockey's Run and Tappan Run. FEMA's study notes that the lower part of Dorotockey's Run floods when the reservoir is high. Check individual addresses on the FEMA Flood Map Service Center.
Does the Oradell Reservoir protect Harrington Park from flooding?
Not reliably. It was built for water supply, not flood control, and FEMA's study notes that when it is high it backs water up Dorotockey's Run, which is one of the ways the borough floods.
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