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Illinois River at LaGrange Lock and Dam

Highest listed crest 34.66 ftFlood stage 23.0 ft41 crests since 1973

The Illinois River at LaGrange Lock and Dam crested at major flood stage 17 times among the 41 crests the National Weather Service lists from 1973 to 2024. The highest, 34.66 ft on July 2, 2015, was major flooding, 11.66 feet above flood stage. 8 other gauges on the Illinois River crested above flood stage within a week of it, 1 at its own highest listed crest.

The gauge

Highest listed crest
34.66 ft
July 2, 2015; 126,400 cubic feet per second
Flood stage
23.0 ft
Major flooding from 29.0 ft
Crests at major
17
13th of 177 gauges in Illinois
Most recent flood crest
February 5, 2024
24.06 ft, minor flooding
Location
Brown County
Illinois

Flood stages

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

Flood categories, Illinois River at LaGrange Lock and Dam
Action stage21.00—The level at which the NWS or its partners begin to take action
Flood stage (minor)23.021Feb 5, 2024Minimal or no property damage, but possibly some public threat
Moderate flood stage27.03Jun 28, 2011Some inundation of structures and roads near the stream
Major flood stage29.017May 27, 2020Extensive inundation of structures and roads

Every listed crest

41 crests from 1973 to 2024. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Illinois River at LaGrange Lock and Dam, 1973 to 2024 2025303540ft Flood stage 23.0 ftMajor 29.0 ft Apr 29, 1973: 32.00 ft, major floodingApr 19, 1979: 32.80 ft, major floodingApr 23, 1993: 30.00 ft, major floodingJul 29, 1993: 32.00 ft, major floodingJun 1, 1995: 34.02 ft, major floodingMar 3, 2001: 26.40 ft, minor floodingJun 2, 2001: 26.10 ft, minor floodingMay 20, 2002: 33.34 ft, major floodingDec 13, 2004: 23.03 ft, minor flooding; 55,355 cubic feet per secondJan 20, 2005: 29.44 ft, major floodingMar 8, 2007: 23.75 ft, minor floodingApr 4, 2007: 25.30 ft, minor floodingJan 19, 2008: 23.60 ft, minor floodingFeb 23, 2008: 25.72 ft, minor floodingJun 16, 2008: 25.22 ft, minor floodingSep 24, 2008: 29.35 ft, major floodingJan 6, 2009: 26.58 ft, minor flooding; 82,900 cubic feet per secondMar 19, 2009: 29.72 ft, major flooding; 101,651 cubic feet per secondMay 22, 2009: 32.00 ft, major flooding; 127,300 cubic feet per secondNov 6, 2009: 27.65 ft, moderate floodingJan 2, 2010: 25.57 ft, minor flooding; 70,500 cubic feet per secondJan 30, 2010: 23.34 ft, minor flooding; 59,000 cubic feet per secondMar 22, 2010: 24.83 ft, minor floodingMay 23, 2010: 25.39 ft, minor floodingJun 29, 2010: 30.42 ft, major floodingMay 4, 2011: 27.47 ft, moderate floodingJun 28, 2011: 27.86 ft, moderate floodingApr 27, 2013: 34.50 ft, major floodingJun 6, 2013: 31.15 ft, major floodingJul 2, 2015: 34.66 ft, major flooding; 126,400 cubic feet per secondApr 14, 2017: 24.78 ft, minor flooding; 57,030 cubic feet per secondMay 8, 2017: 29.75 ft, major flooding; 87,500 cubic feet per secondMar 7, 2018: 26.04 ft, minor flooding; 81,850 cubic feet per secondFeb 17, 2019: 23.93 ft, minor flooding; 68,700 cubic feet per secondFeb 28, 2019: 23.16 ft, minor flooding; 63,570 cubic feet per secondApr 1, 2019: 24.88 ft, minor flooding; 72,064 cubic feet per secondJun 4, 2019: 33.89 ft, major flooding; 118,200 cubic feet per secondJan 24, 2020: 23.62 ft, minor flooding; 60,032 cubic feet per secondMay 27, 2020: 31.35 ft, major flooding; 103,380 cubic feet per secondJul 7, 2021: 24.27 ft, minor flooding; 70,600 cubic feet per secondFeb 5, 2024: 24.06 ft, minor flooding Highest, 34.66 ft, Jul 2, 2015 19801990200020102020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Illinois River at LaGrange Lock and Dam 1970s: 2 1980s: 0 1990s: 3 2000s: 15 2010s: 17 17 2020s: 4 1970s1980s1990s2000s2010s2020s
  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, Illinois River at LaGrange Lock and Dam
1Jul 2, 201534.66+11.66Major126,400
2Apr 27, 201334.50+11.50Major—
3Jun 1, 199534.02+11.02Major—
4Jun 4, 201933.89+10.89Major118,200
5May 20, 200233.34+10.34Major—
6Apr 19, 197932.80+9.80Major—
7Apr 29, 197332.00+9.00Major—
8Jul 29, 199332.00+9.00Major—
9May 22, 200932.00+9.00Major127,300
10May 27, 202031.35+8.35Major103,380
11Jun 6, 201331.15+8.15Major—
12Jun 29, 201030.42+7.42Major—
13Apr 23, 199330.00+7.00Major—
14May 8, 201729.75+6.75Major87,500
15Mar 19, 200929.72+6.72Major101,651
16Jan 20, 200529.44+6.44Major—
17Sep 24, 200829.35+6.35Major—
18Jun 28, 201127.86+4.86Moderate—
19Nov 6, 200927.65+4.65Moderate—
20May 4, 201127.47+4.47Moderate—
21Jan 6, 200926.58+3.58Minor82,900
22Mar 3, 200126.40+3.40Minor—
23Jun 2, 200126.10+3.10Minor—
24Mar 7, 201826.04+3.04Minor81,850
25Feb 23, 200825.72+2.72Minor—
26Jan 2, 201025.57+2.57Minor70,500
27May 23, 201025.39+2.39Minor—
28Apr 4, 200725.30+2.30Minor—
29Jun 16, 200825.22+2.22Minor—
30Apr 1, 201924.88+1.88Minor72,064
31Mar 22, 201024.83+1.83Minor—
32Apr 14, 201724.78+1.78Minor57,030
33Jul 7, 202124.27+1.27Minor70,600
34Feb 5, 202424.06+1.06Minor—
35Feb 17, 201923.93+0.93Minor68,700
36Mar 8, 200723.75+0.75Minor—
37Jan 24, 202023.62+0.62Minor60,032
38Jan 19, 200823.60+0.60Minor—
39Jan 30, 201023.34+0.34Minor59,000
40Feb 28, 201923.16+0.16Minor63,570
41Dec 13, 200423.03+0.03Minor55,355

The worst floods along the Illinois River

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

July 2, 2015: 34.66 ft here, major flooding

  • HardinIL · Jun 30, 2015 · 36.50 ft · Major
  • BeardstownIL · Jul 2, 2015 · 29.75 ft · Major
  • MeredosiaIL · Jul 2, 2015 · 28.86 ft · Major · its highest
  • HavanaIL · Jul 1, 2015 · 27.24 ft · Major
  • Valley CityIL · Jul 2, 2015 · 26.85 ft · Major
  • Peoria Lock and DamIL · Jun 30, 2015 · 454.55 ft · Moderate
  • HenryIL · Jun 30, 2015 · 30.39 ft · Moderate
  • PeoriaIL · Jun 30, 2015 · 27.09 ft · Moderate

April 27, 2013: 34.50 ft here, major flooding

  • Peoria Lock and DamIL · Apr 23, 2013 · 456.57 ft · Major · its highest
  • La SalleIL · Apr 20, 2013 · 34.44 ft · Major · its highest
  • HenryIL · Apr 22, 2013 · 32.94 ft · Major · its highest
  • BeardstownIL · Apr 27, 2013 · 29.81 ft · Major · its highest
  • PeoriaIL · Apr 23, 2013 · 29.35 ft · Major · its highest
  • MeredosiaIL · Apr 27, 2013 · 28.69 ft · Major
  • HavanaIL · Apr 25, 2013 · 27.78 ft · Major · its highest
  • Valley CityIL · Apr 27, 2013 · 26.63 ft · Major

June 1, 1995: 34.02 ft here, major flooding

  • HardinIL · May 29, 1995 · 36.70 ft · Major
  • BeardstownIL · May 30, 1995 · 29.41 ft · Major
  • MeredosiaIL · May 30, 1995 · 28.30 ft · Major
  • Valley CityIL · May 30, 1995 · 26.56 ft · Major
  • HavanaIL · May 31, 1995 · 26.33 ft · Major
  • HenryIL · May 29, 1995 · 28.84 ft · Moderate
  • PeoriaIL · May 30, 1995 · 25.90 ft · Moderate

Gauges on the Illinois River

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

Flood gauges on the Illinois River
BeardstownIL14.029.81 ft, Apr 27, 201310
HardinIL25.042.40 ft, Aug 3, 199320
LaGrange Lock and Dam this gaugeIL23.034.66 ft, Jul 2, 201517
Marseilles Lock (tailwater)IL467.0476.72 ft, Apr 19, 20130
MeredosiaIL17.028.86 ft, Jul 2, 201523
MorrisIL16.024.91 ft, Apr 19, 201312
OttawaIL463.0473.72 ft, Apr 19, 20134
PeoriaIL18.029.35 ft, Apr 23, 20135
Peoria Lock and DamIL447.0456.57 ft, Apr 23, 20135
Starved Rock Lock (tailwater)IL450.0467.81 ft, Apr 19, 20133
Valley CityIL14.027.00 ft, May 26, 194317
HavanaIL14.027.78 ft, Apr 25, 201325
HenryIL23.032.94 ft, Apr 22, 20137
La SalleIL20.034.44 ft, Apr 20, 20139

Brown County: every hazard · River floods across the country · Illinois

NOAA National Water Prediction Service, gauge NLGI2, 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.