Why the Pompton River floods: Pompton Lakes, Wayne, Pequannock and Lincoln Park
Three rivers from the Highlands drain into one short, flat valley, and that valley is where the Pompton runs. The gauge at Pompton Plains, the state flood commission and FEMA claims explain why Pompton Lakes and Wayne file so many flood claims.
The Pompton River collects the Pequannock, Wanaque and Ramapo rivers and carries them a short distance south to the Passaic. At the Pompton Plains gauge it drains 355 square miles. The National Weather Service counted 47 floods there between 1903 and 2018, and Hurricane Irene set the record crest of 25.24 feet in August 2011. This guide explains why the valley floods, what the gauge levels mean on the ground, what the Pompton Lake Dam floodgates do and do not do, and what FEMA records show for Pompton Lakes and Wayne.
The short version
- The Pequannock, Wanaque and Ramapo all drain into the Pompton, which runs through a flat valley to the Passaic at Two Bridges.
- At Pompton Plains the NWS sets major flood stage at 19 feet; Irene crested at 25.24 feet on August 29, 2011, the highest on record.
- The NWS counted 47 floods at Pompton Plains from 1903 to 2018, and five separate major floods in 2011 alone.
- The Pompton Lake Dam floodgates, finished in 2007, protect upstream Oakland; the Army Corps found their effect downstream in March 2010 was about a quarter of a foot.
- FEMA records 2,535 flood claims in Pompton Lakes and 6,318 in Wayne, with Irene the single event with the most claims in both.
Three Highland rivers, one flat valley
The New Jersey Office of Emergency Management describes the Pequannock, Wanaque and Ramapo rivers as all flowing into the Pompton River, a key tributary of the upper Passaic. The state Passaic River Flood Advisory Commission, in its 2011 report to the Governor, puts the meeting point just below a pair of old feeder dams: the Ramapo and the Pequannock join about 1,600 feet downstream of them to form the Pompton. From there the river runs south past Pequannock, Wayne and Lincoln Park to the Passaic at Two Bridges, where the US Geological Survey keeps a gauge on the Passaic below the Pompton. The commission explains the shape of the problem. The upper basin is a band of steep Highland ridges cut by narrow valleys that send runoff down fast and in volume. The central basin is a broad, flat valley that reaches north to Pompton Lakes in what the report calls the Pompton Valley. Flood damage is highest there, the commission says, because development sits right along the streams, the land is low and the stream slopes are flat. Water arrives quickly from the hills and leaves slowly across the flats.
The Pompton Plains gauge and what each level means
The main forecast point is the USGS streamgage on the Pompton River at Pompton Plains (01388500), which has a drainage area of 355 square miles. The National Weather Service sets action stage there at 13 feet, minor flood stage at 16, moderate at 18 and major at 19. Its impact statements turn those numbers into streets. At 12 feet the first flooding begins around River Road and Harrison Street. At 16 feet homes on Pequannock Avenue between Madison and Shady streets are surrounded by water and businesses along Route 23 north begin to flood. At 17 feet Pequannock Avenue at Roosevelt Street and the Route 23 exit ramp at Alexander Avenue become impassable. At 18 feet the first evacuations begin and flooding reaches West View Road and the Lower Riverview area of Wayne. At 18.5 feet Route 23 is closed in both directions. At 19 feet the NWS expects widespread flooding in low-lying parts of Wayne, Pequannock and Pompton Lakes, and at 20 feet the village section of Pompton Plains begins to flood. Above 24 feet portions of the railroad tracks are under water.
The flood record
The NWS Middle Atlantic River Forecast Center lists 47 floods at Pompton Plains from 1903 to 2018, measured against the 16-foot flood stage. The highest crests on the current NWS list are 25.24 feet on August 29, 2011 (Irene), 24.47 feet on April 6, 1984, 22.77 feet on March 14, 2010, 22.18 feet on May 30, 1968, 22.11 feet on March 12, 2011 and 21.72 feet on April 16, 2007. Floyd reached 21.0 feet on September 17, 1999, and December 2023 produced 21.21 feet. The October 1903 flood has no recorded height, but the USGS peak-flow record gives it the largest discharge, 28,300 cubic feet per second, against 25,400 in 1984 and 25,000 in Irene. The year 2011 stands out: the forecast center lists five separate floods at the gauge that year, in March, April, August and September, every one of them above major flood stage. The commission notes that in the March 2010 storm the Pompton at Pompton Plains and the Ramapo at Mahwah each saw roughly a 40-year event, more severe than the 20 to 30-year events measured along the main stem of the Passaic.
The Pompton Lake Dam floodgates
The floodgates at Pompton Lake Dam are the most argued-over structure on these rivers, so it helps to be precise about what they are for. According to the Army Corps of Engineers and the state commission, the project replaced a 90-foot section of the dam with two steel floodgates, each 18 feet high and 35 feet long, and widened and deepened the Ramapo upstream of the lake. It was built by the Army Corps with NJDEP, completed in 2007, and NJDEP took over operation on August 1, 2007; the North Jersey District Water Supply Commission runs it day to day. Its purpose is to protect roughly 300 homes upstream in Oakland, where water used to back up behind the dam. A computer reads the lake every 15 minutes; when it is about 1.5 feet above normal the gates open 3 inches, and then further as the lake rises. The gates were designed to give no benefit to downstream towns and to do them no harm. After March 2010 the Army Corps estimated that gate operation added 214 cubic feet per second to the river and about a quarter of a foot to the peak just below the dam, which it judged not significant. NJDEP then commissioned an independent hydraulic model of the downstream effects.
What has been done besides the gates
The commission issued 15 recommendations in February 2011. Those aimed at this valley included faster floodway buyouts with state Blue Acres and FEMA money, better operation of the floodgates, routine de-snagging and shoal removal, and removing the Pompton and Pequannock feeder dams, low structures built in 1928 to replace the old Morris Canal dam, to relieve Pompton Lakes, Wayne and Pequannock. The report also noted that both feeder dams are already submerged in a 10-year flood, which limits what removal can achieve in a large event. Buyouts are the measure with a long record here. The commission listed FEMA Hazard Mitigation Grant acquisitions of 183 homes in Wayne, 31 in Lincoln Park, 10 in Little Falls and 6 in Pompton Lakes. In October 2014 NJDEP announced that 19 Pompton Lakes homeowners had been approved for Blue Acres buyouts, some of whose homes had flooded in Irene and earlier storms. Earlier still, Pequannock, Lincoln Park and Wayne cleared about six miles of the Pompton after the April 1984 flood.
What the FEMA claims show
Flood insurance records show where the damage lands. FEMA NFIP claims data records 2,535 flood claims in Pompton Lakes, a borough of about 11,000 people by the US Census Bureau count. The year with the most was 2011, with 773, and the named event with the most was Hurricane Irene, with 463, followed by the March 2010 nor'easter with 284 and Floyd with 259. FEMA counts 259 repetitive-loss properties in the borough, 111 of them severe repetitive loss. Wayne, a township of about 54,000, has 6,318 NFIP claims on FEMA records, led by Irene with 803, the March 2010 nor'easter with 621 and the April 2007 nor'easter with 553, and 476 repetitive-loss properties, 229 of them severe. Wayne also borders the Passaic, so not every claim there is Pompton water. Either way, the pattern is the same as the gauge record: the same streets flood in storm after storm.
What this means if you own or rent here
Start with the gauge. The NWS page for the Pompton River at Pompton Plains shows the current level, the forecast crest and the impact list above, so a forecast of 18 feet can be read as a likely evacuation on the Lower Riverview side of Wayne rather than as an abstract number. In Pompton Lakes, also watch the Ramapo gauge at Pompton Lakes and the Wanaque gauge at Wanaque, whose impact statements name streets in the borough. Floods here tend to repeat within a season, as 2011 showed, so do not assume the next storm will be smaller because the last one was recent. Keep valuables and records off basement floors, know where the car goes, and never drive through water on Route 23, Pequannock Avenue or any road the gauge says is closed. Flood damage is excluded from standard homeowners and renters policies; it needs a separate flood policy, and whether a particular loss is paid is decided by the insurer under that policy. FEMA notes a new flood policy normally takes 30 days to begin, so it cannot be bought once a storm is forecast. For a specific address, check the FEMA Flood Map Service Center.
Common questions
What is flood stage on the Pompton River at Pompton Plains?
The National Weather Service uses 13 feet as action stage, 16 feet as minor flood stage, 18 feet as moderate and 19 feet as major. The record crest is 25.24 feet, set during Hurricane Irene on August 29, 2011.
Do the Pompton Lake Dam floodgates cause flooding downstream?
The floodgates were built to protect homes upstream in Oakland and were designed to have no effect downstream. The Army Corps of Engineers estimated that during the March 2010 flood their operation raised the peak just below the dam by about 0.25 feet and judged that not significant. Because residents and local officials reported unexpected surges downstream when the gates operated, the state commission asked for an independent hydraulic study, which NJDEP commissioned.
Which towns does the Pompton River flood?
The National Weather Service impact statements for the Pompton Plains gauge name low-lying parts of Wayne, Pequannock and Pompton Lakes, including Pequannock Avenue, Route 23, West View Road and the Lower Riverview area of Wayne. The river also runs past Lincoln Park on its way to the Passaic.
Have homes been bought out along the Pompton?
Yes. The state flood commission listed FEMA-funded acquisitions of 183 homes in Wayne, 31 in Lincoln Park, 10 in Little Falls and 6 in Pompton Lakes, and in 2014 NJDEP approved 19 Pompton Lakes homeowners for Blue Acres buyouts. Buyouts are voluntary.
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