Why the Passaic River floods at Little Falls and Paterson: Woodland Park, Totowa, Clifton and Passaic
Little Falls is where the water of the whole upper Passaic basin leaves the flat central valley. What happens at that gap, and at the Great Falls a few miles on, decides how often Little Falls, Woodland Park, Totowa and Paterson take on water.
At the Little Falls gauge the Passaic River drains 762 square miles of the upper and central basin. The National Weather Service counts 63 floods there since 1903, and the crest of 14.19 feet left by Irene in August 2011 is the highest since the 1903 flood of record. FEMA records 1,902 flood insurance claims in Little Falls Township, 1,337 in Paterson, 661 in Woodland Park and 550 in Totowa. This guide explains the geography, the gauge levels and the flood studies behind those numbers.
The short version
- The Passaic at Little Falls drains 762 square miles; the National Weather Service counts 63 floods there since 1903.
- Major flood stage at Little Falls is 9 feet. Irene crested at 14.19 feet on August 30, 2011, the highest since the 17.5-foot flood of record in 1903.
- FEMA records 1,902 NFIP claims in Little Falls, 1,337 in Paterson, 661 in Woodland Park and 550 in Totowa; Irene is the largest single event in each.
- The Army Corps found levees and floodwalls not economically feasible between Beatties Dam and Deepavaal Brook; buyouts, elevations and floodproofing are the remaining tools there.
- A Peckman River bypass culvert and floodwalls for Little Falls and Woodland Park were authorised in the Water Resources Development Act of 2020.
Where the basin drains out
The state commission that reported to the Governor on Passaic flooding in January 2011 divides the 935 square mile basin into three natural parts. The upper section is Highlands ridge country whose steep valleys send water off quickly. The central section is a crescent-shaped valley 8 to 12 miles wide and about 30 miles long, running from the Great Swamp through Chatham to Pompton Lakes, where, the commission says, natural storage holds back the flashy flows from the hills. The lower section runs from there to Newark Bay, and the commission notes that its slight gradient is broken by three drops: Little Falls, the Great Falls and Dundee Dam. Little Falls is the exit from the central valley. The National Park Service explains that Glacial Lake Passaic was water trapped by the surrounding mountains until, about 14,000 years ago, the retreating glacier let the river find a new route that drained the lake through the chasm of the Great Falls. The old lake bed is the central valley. Everything that falls on it, and on the Pompton, Rockaway and Whippany rivers that feed it, must leave past Little Falls, Woodland Park and Totowa and then over the Great Falls in Paterson.
What the Little Falls gauge records
The weather service flood history for Little Falls runs from 1903, and the site is its main forecast point for this stretch. Action stage is 6.5 feet, minor flood stage 7 feet, moderate 8 feet and major 9 feet. Against the 7-foot flood stage the weather service counts 63 floods between 1903 and its most recent listed event in December 2018. The October 10, 1903 crest of 17.5 feet, recorded on an older datum, remains the flood of record. Since then the highest crests are 14.19 feet on August 30, 2011 (Irene), 12.91 feet on April 7, 1984, 11.88 feet on April 18, 2007, 11.87 feet on March 16, 2010 and 11.81 feet on March 13, 2011. Add 11.05 feet in September 2011, after the remnants of Lee, and 2011 produced three of the six highest modern crests. The commission report adds that the river at Little Falls had seventeen major floods after 1955 and had reached flood stage 32 times over the same period. Major flooding here comes every few years, not once in a lifetime.
What each level means on the ground
The weather service publishes what the Little Falls readings mean street by street. At 5.5 feet the lower end of East Holsman Street in Paterson, closest to the river, begins to flood. At 6.5 feet the lower end of Bergen Street in Paterson follows. At 7 feet minor flooding begins in Lincoln Park, Wayne and Little Falls. At 9 feet portions of River Street, Presidential Boulevard, Bridge Street, Tyler Street, Totowa Avenue and McLean Boulevard in Paterson are flooded. At 9.5 feet homes on William Street and Zeliff Avenue in Little Falls take on water, and the Arch Street and Temple Street bridges in Paterson are subject to closures. At 10 feet water begins to flow over the Temple Street bridge, and at 11.5 feet Tyler, Shady, Arch, Lowe, Wood and Bleeker streets in Paterson are closed. Irene, at 14.19 feet, passed every one of those thresholds. A second forecast point upstream at Singac lists widespread flooding of the Singac section, from the river to Main Street, at 13.5 feet. Singac reached the highest crest on its listed record, 12.44 feet, on December 20, 2023.
Beatties Dam and the narrows
Just above the gauge the river passes over Beatties Dam, which the 2011 commission describes as a masonry dam in the Townships of Little Falls and Wayne with a 267-foot spillway. The commission asked the state to have the Army Corps of Engineers study modifying the dam, over a 3.2-mile reach from Beatties Dam upstream to Two Bridges covering Totowa, Little Falls, Wayne, North Caldwell and Fairfield. In June 2012 the Department of Environmental Protection announced that the Corps reevaluation would include that new alternative. The commission also recorded the Corps finding that along the Passaic between Beatties Dam and the upstream limit of Deepavaal Brook, levees and floodwalls would constrict the water and raise flood stages to the point where they are not economically feasible, and would increase flooding both upstream and downstream. For this reach the only economical measures the Corps found were floodproofing, elevating and removing buildings. In 2014 the Corps and the state narrowed the basin-wide options to three: levees and floodwalls combined with buyouts and elevations, the diversion tunnel to Newark Bay first authorised in 1990, and a purely nonstructural plan.
The Peckman River in Woodland Park and Little Falls
Not all of the flooding in Woodland Park and Little Falls comes from the Passaic itself. The Peckman River joins it there, and the Army Corps notice of 2017 describes flood damage in the Peckman basin from intense thunderstorms and heavy rainfall on extensively developed land. That means short warning and fast water, and the 2011 commission singled out flash-flood planning for Woodland Park and Little Falls. The plan the state asked the Corps to pursue combines a bypass culvert to divert Peckman floodwater, a levee and floodwall system in Little Falls, and floodwalls along Great Notch Brook in Woodland Park, designed against the 1 per cent annual chance flood from the Peckman. The Borough of Woodland Park reported in January 2021 that the Water Resources Development Act of 2020 authorised the Corps to build the project. The sources reviewed here do not show whether construction has begun; check with the borough or the Corps.
Paterson, Clifton and Passaic
Below Little Falls the river runs through Totowa and around Paterson to the Great Falls, which the National Park Service describes as a 77-foot waterfall plunging into a dark basalt chasm. The 1903 storm put 15.5 inches of rain on Paterson, the highest total in the basin, according to the commission. Downstream the next forecast point is Dundee Dam at Clifton, where the weather service says Pulaski Park in Paterson is submerged at 6.5 feet and commercial property near Route 21 in Paterson floods at 9 feet. Below Dundee Dam the river is tidal. The FEMA claims record for Clifton and the city of Passaic looks different: Hurricane Ida in 2021, an intense-rain storm, accounts for 40 of Clifton’s 164 lifetime claims and 34 of the city of Passaic’s 160.
The insurance record, town by town
FEMA’s National Flood Insurance Program claims file shows where this reach floods. Little Falls Township, a town of 14,790 people according to the US Census Bureau, has 1,902 lifetime NFIP claims, with 588 in 2011 alone, and FEMA lists 229 repetitive-loss properties there, 85 of them severe repetitive-loss. Paterson has 1,337 claims, with 454 in 2011, and 196 repetitive-loss properties, 48 of them severe. Woodland Park has 661 claims and 115 repetitive-loss properties, and Totowa 550 claims and 49. Irene is the single largest event in all four: 309 claims in Little Falls, 304 in Paterson, 219 in Totowa and 184 in Woodland Park. In Totowa, Hurricane Floyd in 1999 comes second with 104. These counts include every flood source, not only the Passaic. Tenure matters too: the US Census Bureau puts Paterson’s renter share at 73.1 per cent, so many of the households exposed here are tenants whose belongings are not covered by the building owner’s policy.
What this means if you own or rent here
Watch the Little Falls forecast, not just the rain. Its weather service page shows the predicted crest, and the list above turns it into streets. On this river the crest can come well after the storm: Irene made landfall in New Jersey on August 28, 2011, and the Little Falls gauge did not crest until August 30. Along the Peckman and the small brooks the opposite holds, and water can rise within hours. Move cars and valuables early, never walk or drive into moving water, and treat water indoors as an electrical hazard until power is off. Flood is a separate policy from homeowners or renters insurance, and FEMA states that a new policy normally takes effect 30 days after purchase, so it cannot be arranged once a crest is forecast. Renters can buy flood cover for contents alone. Whether a given loss is paid is decided by the policy and the insurer. For the zone at a particular address use the FEMA Flood Map Service Center, and ask the township about any elevation or buyout programme before planning major work.
Common questions
Why does Little Falls flood so often?
Little Falls sits at the exit of the central Passaic valley, the bed of the former Glacial Lake Passaic, and all of that valley’s water, plus the Pompton, Rockaway and Whippany rivers, leaves past it. The National Weather Service counts 63 floods at the gauge since 1903, and FEMA records 1,902 flood insurance claims in the township.
What is flood stage on the Passaic River at Little Falls?
The National Weather Service uses 6.5 feet as action stage, 7 feet as minor flood stage, 8 feet as moderate and 9 feet as major. The flood of record is 17.5 feet on October 10, 1903, measured on an older datum. The highest modern crest is 14.19 feet on August 30, 2011, during Irene.
Which Paterson streets flood when the Passaic rises?
The weather service list for the Little Falls gauge names the lower ends of East Holsman Street and Bergen Street first, at 5.5 and 6.5 feet, then parts of River Street, Bridge Street, Totowa Avenue and McLean Boulevard at 9 feet, with bridge closures at Arch Street, Temple Street and West Broadway between 9.5 and 11 feet.
Is anything being built to stop the flooding?
Not on the main river at Little Falls. The Army Corps and the state narrowed basin-wide options to three in 2014, and the Corps had already found walls unworkable in the reach above Beatties Dam. The 2011 commission recorded 10 FEMA-funded home acquisitions and 39 elevations in Little Falls. On the Peckman River, a bypass culvert and floodwalls for Little Falls and Woodland Park were authorised by Congress in 2020.
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