Flooding in Woodcliff Lake, New Jersey: the flood zone, the reservoir, and what to do
A borough named after a reservoir invites the question of whether the reservoir floods it. The FEMA record suggests not often: Woodcliff Lake has one of the smaller flood claim counts in the Pascack Valley, even though a fair share of its land is mapped as flood zone.
FEMA counts 30 National Flood Insurance Program claims in Woodcliff Lake and three repetitive-loss properties, none severe. The Bergen County 2026 Hazard Mitigation Plan puts 8.54 per cent of the borough's land in the 1 per cent annual chance flood zone, and much of that low ground lines the reservoir and the brooks that feed it. The water supply reservoir on Pascack Brook is not a flood-control structure. For most homes here, storm drainage and basements matter more than the lake.
The short version
- FEMA records 30 flood insurance claims in Woodcliff Lake and three repetitive-loss properties, none severe.
- The Bergen County 2026 Hazard Mitigation Plan puts 8.54 per cent of the borough's land in the 1 per cent annual chance flood zone, much of it along the reservoir and its brooks.
- The Woodcliff Lake reservoir is run for water supply and is not a flood-control structure.
- The April 2007 nor'easter, not Irene, produced the borough's busiest claim year.
- The borough plans to update its flood mapping and remap storm water outfalls.
A small claims record
FEMA's National Flood Insurance Program data record 30 claims in the Borough of Woodcliff Lake over the life of the programme. The heaviest year was 2007, with 6, then 2011 with 5, 2010 with 4 and 2012 with 3. By named event, FEMA attributes 5 claims to the April 2007 nor'easter, 4 to Hurricane Irene, 3 to the March 2010 nor'easter and 2 to Hurricane Floyd. FEMA's multiple-loss data, as of 2 August 2026, list three repetitive-loss properties and no severe ones. The US Census Bureau counts 2,235 housing units, so by our arithmetic that is about 13 claims per 1,000 homes, against roughly 111 in Hillsdale, the borough immediately downstream on Pascack Brook.
Where the flood zone lies
Table 4.6-1 of the Bergen County 2026 Hazard Mitigation Plan measures 193.95 acres of Woodcliff Lake, 8.54 per cent of its land, in FEMA's Special Flood Hazard Area, rising to 10.36 per cent with the 0.2 per cent annual chance zone. The contrast with the claim count likely reflects where that zone lies. Pascack Brook is dammed to form the Woodcliff Lake reservoir, and FEMA's flood study models the lake for both Woodcliff Lake and Hillsdale. Bear Brook, which drains about 2.36 square miles from the Montvale and Park Ridge side, enters the reservoir, and the study also maps Hillsdale Brook in the borough. The Musquapsink Brook begins here too, before flowing south through Hillsdale.
What the reservoir does in a storm
FEMA's Flood Insurance Study is direct about the reservoir: it is owned and operated for public water supply and is not designed or used for flood control, although its storage has a natural damping effect on most flood peaks downstream. The state lists the Woodcliff Lake Dam as a high hazard potential dam, a classification based on what a failure would affect, under the Borough of Hillsdale, where the dam stands. The study gives the lake a modelled level of 94.0 feet; the highest stage recorded was 97.65 feet on 2 February 1973. Homes on the lake's edge and along its feeder brooks are the ones that should check the map most carefully.
Rain, not rivers
The borough's worst claim year was 2007, not 2011, which says something about how water reaches homes here. During the April 2007 nor'easter the county plan records Bergen County rainfall ranging from 4.60 inches in Woodcliff Lake, the lowest reported total, to 8.04 inches in Lodi. Even the county's lightest rainfall was enough to produce the borough's busiest claim year, which points to local drainage and small streams rather than a large river. Woodcliff Lake's entry in the county plan lists drainage improvements as completed work, and plans to update its flood mapping and remap its storm water outfalls over the next five years. The county also owns a dam at Wood Dale Park in the borough.
What this means if you own or rent here
Check your address on the FEMA Flood Map Service Center, particularly if you are near the reservoir, Bear Brook, Hillsdale Brook or the head of the Musquapsink. The county plan counts 32 active flood policies in the borough as of October 2024. If you are outside the mapped zone, the practical risks are basement water and overwhelmed drainage: keep downspouts discharging away from the house, test the sump pump before storm season, and read your homeowners policy for its sewer backup and seepage wording. The US Census Bureau puts the median year built at 1967, and about 14 per cent of households rent; renters need their own contents cover. FEMA states that a new flood policy normally takes 30 days to take effect. Whether a particular loss is covered is decided by your insurer and your policy wording.
Common questions
Does Woodcliff Lake, NJ flood?
Not often, by the FEMA record: 30 flood insurance claims over the life of the programme. The county plan does put 8.54 per cent of the borough's land in the 1 per cent annual chance flood zone, so homes near the reservoir and its brooks should check the FEMA map.
Does the Woodcliff Lake reservoir prevent flooding?
Not by design. FEMA's flood study says the reservoir is operated for water supply and is not designed or used for flood control, though its storage dampens most flood peaks downstream.
Which brooks flood in Woodcliff Lake?
FEMA's flood study maps Pascack Brook and the reservoir, Bear Brook where it enters the lake, and Hillsdale Brook in the borough. The Musquapsink Brook also begins in Woodcliff Lake.
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