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Merrimack River at Concord

Highest listed crest 26.20 ftFlood stage 14.0 ft27 crests since 1927

The Merrimack River at Concord crested at major flood stage 3 times among the 27 crests the National Weather Service lists from 1927 to 2006. The highest, 26.20 ft on March 20, 1936, was major flooding, 12.20 feet above flood stage. 5 other gauges on the Merrimack River crested above flood stage within a week of it, 5 at their own highest listed crest.

The gauge

Highest listed crest
26.20 ft
March 20, 1936
Flood stage
14.0 ft
Major flooding from 20.0 ft
Crests at major
3
6th of 34 gauges in New Hampshire
Most recent flood crest
May 15, 2006
15.12 ft, minor flooding
Location
Merrimack County
Near Concord (2.3 mi)

Flood stages

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

Flood categories, Merrimack River at Concord
Action stage12.015Apr 15, 2004The level at which the NWS or its partners begin to take action
Flood stage (minor)14.03May 15, 2006Minimal or no property damage, but possibly some public threat
Moderate flood stage17.00—Some inundation of structures and roads near the stream
Major flood stage20.03Sep 22, 1938Extensive inundation of structures and roads

Every listed crest

27 crests from 1927 to 2006. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Merrimack River at Concord, 1927 to 2006 1015202530ft Flood stage 14.0 ftMajor 20.0 ft Nov 5, 1927: 20.80 ft, major floodingMar 20, 1936: 26.20 ft, major floodingSep 22, 1938: 23.00 ft, major floodingApr 4, 1951: 14.40 ft, minor floodingMar 28, 1953: 13.69 ft, action stageApr 19, 1969: 14.28 ft, minor floodingDec 23, 1973: 13.03 ft, action stageMay 21, 1983: 11.86 ft, below flood stage; 23,830 cubic feet per secondMay 31, 1984: 12.92 ft, action stage; 27,260 cubic feet per secondApr 1, 1986: 11.84 ft, below flood stage; 23,770 cubic feet per secondMar 3, 1987: 13.41 ft, action stage; 29,140 cubic feet per secondMay 1, 1988: 12.41 ft, action stage; 25,700 cubic feet per secondMay 8, 1989: 12.03 ft, action stage; 24,400 cubic feet per secondApr 24, 1991: 11.51 ft, below flood stage; 23,300 cubic feet per secondOct 8, 1991: 11.95 ft, below flood stage; 24,100 cubic feet per secondApr 12, 1993: 12.41 ft, action stage; 25,700 cubic feet per secondApr 15, 1994: 12.55 ft, action stage; 26,150 cubic feet per secondApr 20, 1997: 12.80 ft, action stage; 26,900 cubic feet per secondMar 31, 1998: 13.63 ft, action stage; 29,955 cubic feet per secondSep 18, 1999: 13.28 ft, action stage; 29,000 cubic feet per secondApr 11, 2000: 12.34 ft, action stage; 25,100 cubic feet per secondApr 25, 2001: 12.67 ft, action stage; 26,510 cubic feet per secondApr 16, 2002: 12.37 ft, action stage; 25,965 cubic feet per secondMar 31, 2003: 11.31 ft, below flood stage; 22,540 cubic feet per secondApr 15, 2004: 12.53 ft, action stage; 26,090 cubic feet per secondApr 6, 2005: 11.86 ft, below flood stage; 23,830 cubic feet per secondMay 15, 2006: 15.12 ft, minor flooding; 35,420 cubic feet per second Highest, 26.20 ft, Mar 20, 1936 19301940195019601970198019902000

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Merrimack River at Concord 1920s: 1 1930s: 2 2 1940s: 0 1950s: 1 1960s: 1 1970s: 0 1980s: 0 1990s: 0 2000s: 1 1920s1930s1940s1950s1960s1970s1980s1990s2000s
  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.
  3. 1 crest measured on an earlier gauge datum is left out: 14.65 ft on Apr 6, 1960.

Highest crests

Highest listed crests, Merrimack River at Concord
1Mar 20, 193626.20+12.20Major—
2Sep 22, 193823.00+9.00Major—
3Nov 5, 192720.80+6.80Major—
4May 15, 200615.12+1.12Minor35,420
5Apr 4, 195114.40+0.40Minor—
6Apr 19, 196914.28+0.28Minor—
7Mar 28, 195313.69−0.31Action—
8Mar 31, 199813.63−0.37Action29,955
9Mar 3, 198713.41−0.59Action29,140
10Sep 18, 199913.28−0.72Action29,000
11Dec 23, 197313.03−0.97Action—
12May 31, 198412.92−1.08Action27,260
13Apr 20, 199712.80−1.20Action26,900
14Apr 25, 200112.67−1.33Action26,510
15Apr 15, 199412.55−1.45Action26,150
16Apr 15, 200412.53−1.47Action26,090
17May 1, 198812.41−1.59Action25,700
18Apr 12, 199312.41−1.59Action25,700
19Apr 16, 200212.37−1.63Action25,965
20Apr 11, 200012.34−1.66Action25,100
21May 8, 198912.03−1.97Action24,400
22Oct 8, 199111.95−2.05Below flood stage24,100
23May 21, 198311.86−2.14Below flood stage23,830
24Apr 6, 200511.86−2.14Below flood stage23,830
25Apr 1, 198611.84−2.16Below flood stage23,770
26Apr 24, 199111.51−2.49Below flood stage23,300
27Mar 31, 200311.31−2.69Below flood stage22,540

The worst floods along the Merrimack River

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

March 20, 1936: 26.20 ft here, major flooding

  • LowellMA · Mar 20, 1936 · 68.40 ft · Major · its highest
  • NashuaNH · Mar 20, 1936 · 41.30 ft · Major · its highest
  • Franklin Jct.NH · Mar 19, 1936 · 36.40 ft · Major · its highest
  • Goffs FallsNH · Mar 20, 1936 · 35.19 ft · Major · its highest
  • HaverhillMA · Mar 20, 1936 · 25.75 ft · Major · its highest

September 22, 1938: 23.00 ft here, major flooding

  • LowellMA · Sep 23, 1938 · 60.57 ft · Major
  • Franklin Jct.NH · Sep 22, 1938 · 29.50 ft · Major
  • Goffs FallsNH · Sep 23, 1938 · 25.87 ft · Major
  • NashuaNH · Sep 23, 1938 · 30.50 ft · Moderate

November 5, 1927: 20.80 ft here, major flooding

  • Franklin Jct.NH · Nov 5, 1927 · 30.85 ft · Major
  • LowellMA · Nov 5, 1927 · 56.50 ft · Moderate

Gauges on the Merrimack River

Flood gauges sharing the river's name, linked within 80 miles of one another.

Flood gauges on the Merrimack River
Franklin Jct.NH16.036.40 ft, Mar 19, 19363
Concord this gaugeNH14.026.20 ft, Mar 20, 19363
Goffs FallsNH11.035.19 ft, Mar 20, 19364
NashuaNH18.041.30 ft, Mar 20, 19361
LowellMA52.068.40 ft, Mar 20, 19365
LawrenceMA24.025.37 ft, Dec 20, 20230
HaverhillMA11.025.75 ft, Mar 20, 19363

Other gauges in Merrimack County

Flood gauges in Merrimack County
Henniker12.021.30 ft, Sep 21, 19381
Franklin Jct.16.036.40 ft, Mar 19, 19363
Bristol8.016.09 ft, Mar 19, 19361
North Chichester7.015.97 ft, Apr 17, 20070
Davisville8.012.80 ft, Sep 22, 19382
Tilton7.08.68 ft, May 31, 19842

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

NOAA National Water Prediction Service, gauge CONN3, 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.