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North Branch Raritan River at South Branch

Highest listed crest 20.26 ftFlood stage 8.0 ft27 crests since 1896

The North Branch Raritan River at South Branch crested at major flood stage 14 times among the 27 crests the National Weather Service lists from 1896 to 2026. The highest, 20.26 ft on September 2, 2021, was major flooding, 12.26 feet above flood stage. 3 other gauges on the North Branch Raritan River crested above flood stage within a week of it, 1 at its own highest listed crest.

The gauge

Highest listed crest
20.26 ft
September 2, 2021
Flood stage
8.0 ft
Major flooding from 11.0 ft
Crests at major
14
4th of 125 gauges in New Jersey
Most recent flood crest
March 6, 2026
8.27 ft, minor flooding
Location
Somerset County
Near Somerville (4.3 mi), Manville (5.3 mi), Bound Brook (7.9 mi)

Flood stages

The thresholds the National Weather Service uses for this gauge today, and how many listed crests reached each.

Flood categories, North Branch Raritan River at South Branch
Action stage7.01Dec 17, 2000The level at which the NWS or its partners begin to take action
Flood stage (minor)8.04Mar 6, 2026Minimal or no property damage, but possibly some public threat
Moderate flood stage9.08Dec 11, 2023Some inundation of structures and roads near the stream
Major flood stage11.014Jan 10, 2024Extensive inundation of structures and roads

Every listed crest

27 crests from 1896 to 2026. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the North Branch Raritan River at South Branch, 1896 to 2026 510152025ft Flood stage 8.0 ftMajor 11.0 ft Feb 6, 1896: 18.00 ft, major floodingAug 19, 1955: 16.45 ft, major floodingJan 19, 1996: 13.91 ft, major floodingOct 19, 1996: 15.60 ft, major floodingSep 16, 1999: 18.98 ft, major floodingDec 17, 2000: 7.86 ft, action stageJun 4, 2003: 8.54 ft, minor floodingSep 29, 2004: 11.08 ft, major floodingApr 3, 2005: 11.31 ft, major floodingApr 16, 2007: 14.31 ft, major floodingAug 28, 2011: 17.69 ft, major floodingMar 30, 2014: 8.80 ft, minor floodingMay 1, 2014: 13.52 ft, major floodingNov 25, 2018: 10.80 ft, moderate floodingAug 5, 2020: 8.11 ft, minor floodingDec 1, 2020: 9.58 ft, moderate floodingDec 25, 2020: 10.10 ft, moderate floodingJul 18, 2021: 10.64 ft, moderate floodingAug 23, 2021: 10.58 ft, moderate floodingSep 2, 2021: 20.26 ft, major floodingApr 8, 2022: 10.44 ft, moderate floodingJul 10, 2023: 9.36 ft, moderate floodingDec 11, 2023: 9.24 ft, moderate floodingDec 18, 2023: 13.78 ft, major floodingDec 28, 2023: 11.57 ft, major floodingJan 10, 2024: 14.28 ft, major floodingMar 6, 2026: 8.27 ft, minor flooding Highest, 20.26 ft, Sep 2, 2021 1900192019401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, North Branch Raritan River at South Branch 1890s: 1 1900s: 0 1910s: 0 1920s: 0 1930s: 0 1940s: 0 1950s: 1 1960s: 0 1970s: 0 1980s: 0 1990s: 3 2000s: 4 2010s: 4 2020s: 13 13 1890s1900s1910s1920s1930s1940s1950s1960s1970s1980s1990s2000s2010s2020s
  1. These are the crests the local National Weather Service office lists for the gauge: the highest on record and recent crests. Lesser floods between them may be missing, so counts by decade are a floor.
  2. Categories use today's flood stages. Levees, dams and channel changes since a crest can make old and new stages not directly comparable.

Highest crests

Highest listed crests, North Branch Raritan River at South Branch
1Sep 2, 202120.26+12.26Major—
2Sep 16, 199918.98+10.98Major—
3Feb 6, 189618.00+10.00Major—
4Aug 28, 201117.69+9.69Major—
5Aug 19, 195516.45+8.45Major—
6Oct 19, 199615.60+7.60Major—
7Apr 16, 200714.31+6.31Major—
8Jan 10, 202414.28+6.28Major—
9Jan 19, 199613.91+5.91Major—
10Dec 18, 202313.78+5.78Major—
11May 1, 201413.52+5.52Major—
12Dec 28, 202311.57+3.57Major—
13Apr 3, 200511.31+3.31Major—
14Sep 29, 200411.08+3.08Major—
15Nov 25, 201810.80+2.80Moderate—
16Jul 18, 202110.64+2.64Moderate—
17Aug 23, 202110.58+2.58Moderate—
18Apr 8, 202210.44+2.44Moderate—
19Dec 25, 202010.10+2.10Moderate—
20Dec 1, 20209.58+1.58Moderate—
21Jul 10, 20239.36+1.36Moderate—
22Dec 11, 20239.24+1.24Moderate—
23Mar 30, 20148.80+0.80Minor—
24Jun 4, 20038.54+0.54Minor—
25Mar 6, 20268.27+0.27Minor—
26Aug 5, 20208.11+0.11Minor—
27Dec 17, 20007.86−0.14Action—

The worst floods along the North Branch Raritan River

For this gauge's highest crests, the other gauges on the North Branch Raritan River that crested above flood stage within a week.

September 2, 2021: 20.26 ft here, major flooding

September 16, 1999: 18.98 ft here, major flooding

August 28, 2011: 17.69 ft here, major flooding

Gauges on the North Branch Raritan River

In USGS station-number order, which runs downstream within a river basin.

Flood gauges on the North Branch Raritan River
Far HillsNJ6.07.60 ft, Jul 23, 19190
North Branch VillageNJ12.321.53 ft, Sep 16, 19990
RaritanNJ10.019.52 ft, Sep 2, 20216
South Branch this gaugeNJ8.020.26 ft, Sep 2, 202114

Other gauges in Somerset County

Flood gauges in Somerset County
Seeley Mills5.59.05 ft, Sep 2, 20210
Burnt Mills11.016.79 ft, Sep 2, 20214
Bound Brook11.020.66 ft, Sep 2, 20210
Burnt Mills9.512.76 ft, Sep 2, 20211
Blackwells Mills9.021.24 ft, Aug 28, 201111
Griggstown10.024.21 ft, Aug 28, 201114
Millstone10.022.45 ft, Sep 2, 20216
Weston11.523.75 ft, Sep 2, 20217
North Branch Village12.321.53 ft, Sep 16, 19990
Far Hills6.07.60 ft, Jul 23, 19190
Raritan10.019.52 ft, Sep 2, 20216
Millington8.010.26 ft, Aug 29, 20112
Bound Brook28.042.13 ft, Sep 17, 199913
Manville14.027.66 ft, Sep 2, 202110
North Plainfield7.010.65 ft, Aug 2, 19730
Watchung14.024.50 ft, Aug 2, 19730
Martinsville6.011.47 ft, Sep 2, 20210

Somerset County: every hazard · River floods across the country · New Jersey

NOAA National Water Prediction Service, gauge SBRN4, retrieved October 30, 2026. Stages in feet on the gauge's own datum, not elevation. Crests are as the National Weather Service lists them; preliminary values may be revised.