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Illinois River at Marseilles Lock (tailwater)

Highest listed crest 476.72 ftFlood stage 467.0 ft15 crests since 1936

The Illinois River at Marseilles Lock (tailwater) crested above flood stage 15 times among the 15 crests the National Weather Service lists from 1936 to 2020. The highest, 476.72 ft on April 19, 2013, was minor flooding, 9.72 feet above flood stage. 8 other gauges on the Illinois River crested above flood stage within a week of it, 8 at their own highest listed crest.

The gauge

Highest listed crest
476.72 ft
April 19, 2013
Flood stage
467.0 ft
No major stage set
Crests at major
0
15 above flood stage
Most recent flood crest
May 19, 2020
475.84 ft, minor flooding
Location
LaSalle County
Near Ottawa (4.0 mi), Streator (14.6 mi)
Identifiers
NWS MMOI2
No USGS station

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 Marseilles Lock (tailwater)
Action stage466.50—The level at which the NWS or its partners begin to take action
Flood stage (minor)467.015May 19, 2020Minimal or no property damage, but possibly some public threat

Every listed crest

15 crests from 1936 to 2020. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Illinois River at Marseilles Lock (tailwater), 1936 to 2020 466468470472474476478ft Flood stage 467.0 ft Feb 25, 1936: 473.20 ft, minor floodingDec 5, 1982: 473.86 ft, minor floodingApr 9, 1983: 474.70 ft, minor floodingJul 19, 1996: 472.71 ft, minor floodingFeb 22, 1997: 474.83 ft, minor floodingAug 25, 2007: 472.76 ft, minor floodingSep 16, 2008: 475.89 ft, minor floodingDec 29, 2008: 472.33 ft, minor floodingApr 19, 2013: 476.72 ft, minor floodingJun 14, 2015: 470.38 ft, minor floodingDec 30, 2015: 471.12 ft, minor floodingMay 2, 2017: 469.00 ft, minor floodingFeb 22, 2018: 474.26 ft, minor floodingMay 2, 2019: 474.18 ft, minor floodingMay 19, 2020: 475.84 ft, minor flooding Highest, 476.72 ft, Apr 19, 2013 19401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Illinois River at Marseilles Lock (tailwater) 1930s: 1 1940s: 0 1950s: 0 1960s: 0 1970s: 0 1980s: 2 1990s: 2 2000s: 3 2010s: 6 6 2020s: 1 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, Illinois River at Marseilles Lock (tailwater)
1Apr 19, 2013476.72+9.72Minor—
2Sep 16, 2008475.89+8.89Minor—
3May 19, 2020475.84+8.84Minor—
4Feb 22, 1997474.83+7.83Minor—
5Apr 9, 1983474.70+7.70Minor—
6Feb 22, 2018474.26+7.26Minor—
7May 2, 2019474.18+7.18Minor—
8Dec 5, 1982473.86+6.86Minor—
9Feb 25, 1936473.20+6.20Minor—
10Aug 25, 2007472.76+5.76Minor—
11Jul 19, 1996472.71+5.71Minor—
12Dec 29, 2008472.33+5.33Minor—
13Dec 30, 2015471.12+4.12Minor—
14Jun 14, 2015470.38+3.38Minor—
15May 2, 2017469.00+2.00Minor—

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.

April 19, 2013: 476.72 ft here, minor flooding

  • OttawaIL · Apr 19, 2013 · 473.72 ft · Major · its highest
  • Starved Rock Lock (tailwater)IL · Apr 19, 2013 · 467.81 ft · Major · its highest
  • 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
  • PeoriaIL · Apr 23, 2013 · 29.35 ft · Major · its highest
  • HavanaIL · Apr 25, 2013 · 27.78 ft · Major · its highest
  • MorrisIL · Apr 19, 2013 · 24.91 ft · Major · its highest

September 16, 2008: 475.89 ft here, minor flooding

  • OttawaIL · Sep 16, 2008 · 472.21 ft · Major
  • Starved Rock Lock (tailwater)IL · Sep 16, 2008 · 467.31 ft · Major
  • La SalleIL · Sep 16, 2008 · 33.79 ft · Major
  • MorrisIL · Sep 16, 2008 · 24.84 ft · Major
  • HavanaIL · Sep 23, 2008 · 23.54 ft · Major
  • Peoria Lock and DamIL · Sep 19, 2008 · 454.30 ft · Moderate
  • HardinIL · Sep 19, 2008 · 31.68 ft · Moderate
  • HenryIL · Sep 19, 2008 · 30.98 ft · Moderate
  • PeoriaIL · Sep 20, 2008 · 27.06 ft · Moderate

May 19, 2020: 475.84 ft here, minor flooding

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 DamIL23.034.66 ft, Jul 2, 201517
Marseilles Lock (tailwater) this gaugeIL467.0476.72 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

Other gauges in LaSalle County

Flood gauges in LaSalle County
Dayton12.036.47 ft, Jan 25, 19605
Ottawa463.0473.72 ft, Apr 19, 20134
Starved Rock Lock (tailwater)450.0467.81 ft, Apr 19, 20133
La Salle20.034.44 ft, Apr 20, 20139
Leonore16.030.25 ft, Apr 18, 20132

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

NOAA National Water Prediction Service, gauge MMOI2, 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.