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Millstone River at Blackwells Mills

Highest listed crest 21.24 ftFlood stage 9.0 ft50 crests since 1938

The Millstone River at Blackwells Mills crested at major flood stage 11 times among the 50 crests the National Weather Service lists from 1938 to 2024. The highest, 21.24 ft on August 28, 2011, was major flooding, 12.24 feet above flood stage. 3 other gauges on the Millstone River crested above flood stage within a week of it, 1 at its own highest listed crest.

The gauge

Highest listed crest
21.24 ft
August 28, 2011; 26,800 cubic feet per second
Flood stage
9.0 ft
Major flooding from 15.0 ft
Crests at major
11
10th of 125 gauges in New Jersey
Most recent flood crest
January 10, 2024
13.29 ft, moderate flooding
Location
Somerset County
Near Manville (4.6 mi), Bound Brook (6.7 mi), Somerville (6.8 mi)

Flood stages

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

Flood categories, Millstone River at Blackwells Mills
Action stage7.02May 19, 2002The level at which the NWS or its partners begin to take action
Flood stage (minor)9.010Dec 26, 2020Minimal or no property damage, but possibly some public threat
Moderate flood stage10.027Jan 10, 2024Some inundation of structures and roads near the stream
Major flood stage15.011Sep 2, 2021Extensive inundation of structures and roads

Every listed crest

50 crests from 1938 to 2024. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Millstone River at Blackwells Mills, 1938 to 2024 510152025ft Flood stage 9.0 ftMajor 15.0 ft Sep 21, 1938: 15.29 ft, major flooding; 18,300 cubic feet per secondAug 19, 1955: 12.12 ft, moderate flooding; 6,500 cubic feet per secondAug 28, 1971: 18.68 ft, major flooding; 22,200 cubic feet per secondDec 21, 1973: 13.21 ft, moderate flooding; 9,080 cubic feet per secondJul 15, 1975: 16.84 ft, major flooding; 17,100 cubic feet per secondJul 21, 1975: 14.63 ft, moderate flooding; 12,000 cubic feet per secondSep 25, 1975: 13.47 ft, moderate flooding; 10,000 cubic feet per secondJan 27, 1978: 14.02 ft, moderate flooding; 10,700 cubic feet per secondMay 30, 1984: 12.87 ft, moderate flooding; 8,460 cubic feet per secondApr 5, 1987: 11.02 ft, moderate flooding; 5,460 cubic feet per secondJun 10, 1989: 10.76 ft, moderate flooding; 6,190 cubic feet per secondSep 21, 1989: 14.42 ft, moderate flooding; 11,400 cubic feet per secondDec 12, 1992: 12.97 ft, moderate flooding; 9,160 cubic feet per secondJan 29, 1994: 13.88 ft, moderate flooding; 10,500 cubic feet per secondMar 11, 1994: 12.58 ft, moderate flooding; 8,590 cubic feet per secondJan 20, 1996: 15.09 ft, major flooding; 12,600 cubic feet per secondJan 28, 1996: 9.89 ft, minor flooding; 5,240 cubic feet per secondAug 1, 1996: 8.67 ft, action stage; 4,050 cubic feet per secondOct 20, 1996: 15.53 ft, major flooding; 13,400 cubic feet per secondDec 2, 1996: 10.49 ft, moderate floodingJul 25, 1997: 11.03 ft, moderate flooding; 5,460 cubic feet per secondJan 24, 1998: 9.83 ft, minor flooding; 5,180 cubic feet per secondMay 11, 1998: 9.69 ft, minor flooding; 5,030 cubic feet per secondMar 22, 1999: 10.46 ft, moderate flooding; 5,850 cubic feet per secondSep 17, 1999: 21.01 ft, major flooding; 26,200 cubic feet per secondMay 19, 2002: 7.42 ft, action stage; 3,020 cubic feet per secondJun 5, 2003: 11.02 ft, moderate floodingNov 20, 2003: 9.92 ft, minor floodingDec 12, 2003: 11.87 ft, moderate floodingApr 3, 2005: 11.41 ft, moderate flooding; 6,530 cubic feet per secondApr 16, 2007: 19.24 ft, major flooding; 21,600 cubic feet per secondMar 14, 2010: 16.15 ft, major floodingMar 31, 2010: 11.89 ft, moderate floodingMar 7, 2011: 9.88 ft, minor flooding; 4,308 cubic feet per secondMar 12, 2011: 9.19 ft, minor flooding; 3,632 cubic feet per secondAug 28, 2011: 21.24 ft, major flooding; 26,800 cubic feet per secondSep 9, 2011: 13.77 ft, moderate flooding; 10,061 cubic feet per secondMar 31, 2014: 9.94 ft, minor flooding; 4,655 cubic feet per secondMay 1, 2014: 15.87 ft, major flooding; 11,770 cubic feet per secondJan 19, 2015: 9.68 ft, minor floodingMay 28, 2018: 12.58 ft, moderate flooding; 7,468 cubic feet per secondNov 26, 2018: 12.02 ft, moderate flooding; 6,821 cubic feet per secondDec 1, 2020: 9.44 ft, minor flooding; 4,189 cubic feet per secondDec 26, 2020: 9.50 ft, minor flooding; 4,244 cubic feet per secondAug 23, 2021: 14.30 ft, moderate flooding; 9,618 cubic feet per secondSep 2, 2021: 20.81 ft, major flooding; 20,031 cubic feet per secondApr 8, 2022: 10.84 ft, moderate flooding; 5,546 cubic feet per secondDec 19, 2023: 14.22 ft, moderate flooding; 9,512 cubic feet per secondDec 29, 2023: 10.03 ft, moderate flooding; 4,740 cubic feet per secondJan 10, 2024: 13.29 ft, moderate flooding; 8,326 cubic feet per second Highest, 21.24 ft, Aug 28, 2011 19401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Millstone River at Blackwells Mills 1930s: 1 1940s: 0 1950s: 1 1960s: 0 1970s: 6 1980s: 4 1990s: 12 12 2000s: 5 2010s: 11 2020s: 8 1930s1940s1950s1960s1970s1980s1990s2000s2010s2020s
  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, Millstone River at Blackwells Mills
1Aug 28, 201121.24+12.24Major26,800
2Sep 17, 199921.01+12.01Major26,200
3Sep 2, 202120.81+11.81Major20,031
4Apr 16, 200719.24+10.24Major21,600
5Aug 28, 197118.68+9.68Major22,200
6Jul 15, 197516.84+7.84Major17,100
7Mar 14, 201016.15+7.15Major—
8May 1, 201415.87+6.87Major11,770
9Oct 20, 199615.53+6.53Major13,400
10Sep 21, 193815.29+6.29Major18,300
11Jan 20, 199615.09+6.09Major12,600
12Jul 21, 197514.63+5.63Moderate12,000
13Sep 21, 198914.42+5.42Moderate11,400
14Aug 23, 202114.30+5.30Moderate9,618
15Dec 19, 202314.22+5.22Moderate9,512
16Jan 27, 197814.02+5.02Moderate10,700
17Jan 29, 199413.88+4.88Moderate10,500
18Sep 9, 201113.77+4.77Moderate10,061
19Sep 25, 197513.47+4.47Moderate10,000
20Jan 10, 202413.29+4.29Moderate8,326
21Dec 21, 197313.21+4.21Moderate9,080
22Dec 12, 199212.97+3.97Moderate9,160
23May 30, 198412.87+3.87Moderate8,460
24Mar 11, 199412.58+3.58Moderate8,590
25May 28, 201812.58+3.58Moderate7,468
26Aug 19, 195512.12+3.12Moderate6,500
27Nov 26, 201812.02+3.02Moderate6,821
28Mar 31, 201011.89+2.89Moderate—
29Dec 12, 200311.87+2.87Moderate—
30Apr 3, 200511.41+2.41Moderate6,530
31Jul 25, 199711.03+2.03Moderate5,460
32Apr 5, 198711.02+2.02Moderate5,460
33Jun 5, 200311.02+2.02Moderate—
34Apr 8, 202210.84+1.84Moderate5,546
35Jun 10, 198910.76+1.76Moderate6,190
36Dec 2, 199610.49+1.49Moderate—
37Mar 22, 199910.46+1.46Moderate5,850
38Dec 29, 202310.03+1.03Moderate4,740
39Mar 31, 20149.94+0.94Minor4,655
40Nov 20, 20039.92+0.92Minor—
41Jan 28, 19969.89+0.89Minor5,240
42Mar 7, 20119.88+0.88Minor4,308
43Jan 24, 19989.83+0.83Minor5,180
44May 11, 19989.69+0.69Minor5,030
45Jan 19, 20159.68+0.68Minor—
46Dec 26, 20209.50+0.50Minor4,244
47Dec 1, 20209.44+0.44Minor4,189
48Mar 12, 20119.19+0.19Minor3,632
49Aug 1, 19968.67−0.33Action4,050
50May 19, 20027.42−1.58Action3,020

The worst floods along the Millstone River

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

August 28, 2011: 21.24 ft here, major flooding

  • GriggstownNJ · Aug 28, 2011 · 24.21 ft · Major · its highest
  • WestonNJ · Aug 28, 2011 · 22.90 ft · Major
  • MillstoneNJ · Aug 28, 2011 · 22.30 ft · Major

September 17, 1999: 21.01 ft here, major flooding

  • WestonNJ · Sep 17, 1999 · 23.21 ft · Major
  • GriggstownNJ · Sep 16, 1999 · 23.20 ft · Major
  • MillstoneNJ · Sep 17, 1999 · 22.30 ft · Major

September 2, 2021: 20.81 ft here, major flooding

  • WestonNJ · Sep 2, 2021 · 23.75 ft · Major · its highest
  • GriggstownNJ · Sep 2, 2021 · 23.36 ft · Major
  • MillstoneNJ · Sep 2, 2021 · 22.45 ft · Major · its highest

Gauges on the Millstone River

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

Flood gauges on the Millstone River
GriggstownNJ10.024.21 ft, Aug 28, 201114
Blackwells Mills this gaugeNJ9.021.24 ft, Aug 28, 201111
MillstoneNJ10.022.45 ft, Sep 2, 20216
WestonNJ11.523.75 ft, Sep 2, 20217

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
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
South Branch8.020.26 ft, Sep 2, 202114
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 BKWN4, 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.