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Souhegan River at Merrimack

Highest listed crest 16.20 ftFlood stage 9.0 ft47 crests since 1915

The Souhegan River at Merrimack crested at major flood stage 1 time among the 47 crests the National Weather Service lists from 1915 to 2023. The highest, 16.20 ft on March 19, 1936, was major flooding, 7.20 feet above flood stage.

The gauge

Highest listed crest
16.20 ft
March 19, 1936; 16,900 cubic feet per second
Flood stage
9.0 ft
Major flooding from 13.0 ft
Crests at major
1
20th of 34 gauges in New Hampshire
Most recent flood crest
March 31, 2010
9.19 ft, minor flooding
Location
Hillsborough County
Near Nashua (7.5 mi), Manchester (9.3 mi)

Flood stages

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

Flood categories, Souhegan River at Merrimack
Action stage8.020Dec 19, 2023The level at which the NWS or its partners begin to take action
Flood stage (minor)9.016Mar 31, 2010Minimal or no property damage, but possibly some public threat
Moderate flood stage11.03Apr 17, 2007Some inundation of structures and roads near the stream
Major flood stage13.01Mar 19, 1936Extensive inundation of structures and roads

Every listed crest

47 crests from 1915 to 2023. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Souhegan River at Merrimack, 1915 to 2023 681012141618ft Flood stage 9.0 ftMajor 13.0 ft Aug 5, 1915: 9.60 ft, minor flooding; 6,000 cubic feet per secondFeb 27, 1916: 8.68 ft, action stage; 4,740 cubic feet per secondMar 28, 1920: 8.04 ft, action stage; 3,920 cubic feet per secondDec 15, 1920: 9.18 ft, minor flooding; 5,410 cubic feet per secondMay 6, 1922: 8.09 ft, action stage; 3,980 cubic feet per secondApr 8, 1924: 11.82 ft, moderate flooding; 9,260 cubic feet per secondNov 5, 1927: 9.73 ft, minor flooding; 6,180 cubic feet per secondApr 13, 1934: 10.66 ft, minor flooding; 7,500 cubic feet per secondMar 13, 1936: 10.60 ft, minor flooding; 7,340 cubic feet per secondMar 19, 1936: 16.20 ft, major flooding; 16,900 cubic feet per secondNov 14, 1937: 9.92 ft, minor flooding; 6,450 cubic feet per secondNov 29, 1937: 9.01 ft, minor flooding; 5,170 cubic feet per secondSep 21, 1938: 12.78 ft, moderate flooding; 10,800 cubic feet per secondApr 13, 1940: 8.34 ft, action stage; 4,250 cubic feet per secondMar 10, 1942: 8.05 ft, action stage; 3,880 cubic feet per secondJun 25, 1944: 10.88 ft, minor flooding; 7,830 cubic feet per secondMar 23, 1948: 8.10 ft, action stage; 3,990 cubic feet per secondApr 6, 1952: 8.34 ft, action stage; 4,300 cubic feet per secondSep 12, 1954: 8.62 ft, action stage; 4,410 cubic feet per secondOct 16, 1955: 10.30 ft, minor flooding; 6,760 cubic feet per secondJan 10, 1956: 10.00 ft, minor flooding; 6,300 cubic feet per secondApr 3, 1959: 8.36 ft, action stage; 4,180 cubic feet per secondApr 2, 1962: 8.80 ft, action stage; 4,730 cubic feet per secondDec 7, 1962: 7.65 ft, below flood stageDec 7, 1963: 7.65 ft, below flood stageMar 19, 1968: 8.54 ft, action stage; 4,400 cubic feet per secondFeb 11, 1970: 8.48 ft, action stage; 4,400 cubic feet per secondDec 22, 1973: 8.00 ft, action stage; 3,800 cubic feet per secondMar 22, 1983: 8.74 ft, action stage; 4,700 cubic feet per secondApr 6, 1984: 8.50 ft, action stage; 4,420 cubic feet per secondJan 31, 1986: 8.22 ft, action stage; 4,080 cubic feet per secondApr 7, 1987: 10.25 ft, minor flooding; 6,700 cubic feet per secondMar 31, 1993: 7.71 ft, below flood stageDec 25, 1994: 8.16 ft, action stage; 3,980 cubic feet per secondApr 17, 1996: 8.86 ft, action stage; 4,820 cubic feet per secondOct 22, 1996: 9.96 ft, minor flooding; 6,260 cubic feet per secondApr 2, 2004: 9.84 ft, minor flooding; 6,100 cubic feet per secondMay 15, 2006: 9.88 ft, minor flooding; 6,140 cubic feet per secondApr 17, 2007: 12.71 ft, moderate flooding; 10,500 cubic feet per secondMar 15, 2010: 9.85 ft, minor flooding; 6,116 cubic feet per secondMar 31, 2010: 9.19 ft, minor flooding; 5,243 cubic feet per secondApr 7, 2017: 7.06 ft, below flood stage; 2,510 cubic feet per secondOct 31, 2017: 8.14 ft, action stage; 3,680 cubic feet per secondJan 25, 2019: 7.26 ft, below flood stage; 2,720 cubic feet per secondDec 15, 2019: 7.30 ft, below flood stage; 2,780 cubic feet per secondDec 26, 2020: 7.52 ft, below flood stage; 3,000 cubic feet per secondDec 19, 2023: 8.57 ft, action stage; 4,460 cubic feet per second Highest, 16.20 ft, Mar 19, 1936 192019401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Souhegan River at Merrimack 1910s: 1 1920s: 3 1930s: 6 6 1940s: 1 1950s: 2 1960s: 0 1970s: 0 1980s: 1 1990s: 1 2000s: 3 2010s: 2 2020s: 0 1910s1920s1930s1940s1950s1960s1970s1980s1990s2000s2010s2020s
  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, Souhegan River at Merrimack
1Mar 19, 193616.20+7.20Major16,900
2Sep 21, 193812.78+3.78Moderate10,800
3Apr 17, 200712.71+3.71Moderate10,500
4Apr 8, 192411.82+2.82Moderate9,260
5Jun 25, 194410.88+1.88Minor7,830
6Apr 13, 193410.66+1.66Minor7,500
7Mar 13, 193610.60+1.60Minor7,340
8Oct 16, 195510.30+1.30Minor6,760
9Apr 7, 198710.25+1.25Minor6,700
10Jan 10, 195610.00+1.00Minor6,300
11Oct 22, 19969.96+0.96Minor6,260
12Nov 14, 19379.92+0.92Minor6,450
13May 15, 20069.88+0.88Minor6,140
14Mar 15, 20109.85+0.85Minor6,116
15Apr 2, 20049.84+0.84Minor6,100
16Nov 5, 19279.73+0.73Minor6,180
17Aug 5, 19159.60+0.60Minor6,000
18Mar 31, 20109.19+0.19Minor5,243
19Dec 15, 19209.18+0.18Minor5,410
20Nov 29, 19379.01+0.01Minor5,170
21Apr 17, 19968.86−0.14Action4,820
22Apr 2, 19628.80−0.20Action4,730
23Mar 22, 19838.74−0.26Action4,700
24Feb 27, 19168.68−0.32Action4,740
25Sep 12, 19548.62−0.38Action4,410
26Dec 19, 20238.57−0.43Action4,460
27Mar 19, 19688.54−0.46Action4,400
28Apr 6, 19848.50−0.50Action4,420
29Feb 11, 19708.48−0.52Action4,400
30Apr 3, 19598.36−0.64Action4,180
31Apr 13, 19408.34−0.66Action4,250
32Apr 6, 19528.34−0.66Action4,300
33Jan 31, 19868.22−0.78Action4,080
34Dec 25, 19948.16−0.84Action3,980
35Oct 31, 20178.14−0.86Action3,680
36Mar 23, 19488.10−0.90Action3,990
37May 6, 19228.09−0.91Action3,980
38Mar 10, 19428.05−0.95Action3,880
39Mar 28, 19208.04−0.96Action3,920
40Dec 22, 19738.00−1.00Action3,800
41Mar 31, 19937.71−1.29Below flood stage—
42Dec 7, 19627.65−1.35Below flood stage—
43Dec 7, 19637.65−1.35Below flood stage—
44Dec 26, 20207.52−1.48Below flood stage3,000
45Dec 15, 20197.30−1.70Below flood stage2,780
46Jan 25, 20197.26−1.74Below flood stage2,720
47Apr 7, 20177.06−1.94Below flood stage2,510

The worst floods along the Souhegan River

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

April 17, 2007: 12.71 ft here, moderate flooding

  • MilfordNH · Apr 16, 2007 · 12.49 ft · Major · its highest

Gauges on the Souhegan River

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

Flood gauges on the Souhegan River
MilfordNH9.012.49 ft, Apr 16, 20071
Merrimack this gaugeNH9.016.20 ft, Mar 19, 19361

Other gauges in Hillsborough County

Flood gauges in Hillsborough County
Peterborough5.515.00 ft, Sep 21, 19381
Goffs Falls11.035.19 ft, Mar 20, 19364
Nashua18.041.30 ft, Mar 20, 19361
Goffstown9.017.52 ft, Sep 21, 19384
Milford9.012.49 ft, Apr 16, 20071

Hillsborough County: every hazard · River floods across the country · New Hampshire

NOAA National Water Prediction Service, gauge SOHN3, 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.