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Fox River at Algonquin tailwater

Highest listed crest 14.00 ftFlood stage 9.5 ft29 crests since 1938

The Fox River at Algonquin tailwater crested at major flood stage 6 times among the 29 crests the National Weather Service lists from 1938 to 2024. The highest, 14.00 ft on July 5, 1938, was major flooding, 4.50 feet above flood stage. 4 other gauges on the Fox River crested above flood stage within a week of it, 3 at their own highest listed crest.

The gauge

Highest listed crest
14.00 ft
July 5, 1938
Flood stage
9.5 ft
Major flooding from 12.0 ft
Crests at major
6
48th of 177 gauges in Illinois
Most recent flood crest
April 9, 2024
10.42 ft, minor flooding
Location
McHenry County
Near Algonquin (1.4 mi), Lake in the Hills (1.6 mi), Carpentersville (2.7 mi)

Flood stages

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

Flood categories, Fox River at Algonquin tailwater
Action stage9.04Jul 18, 2024The level at which the NWS or its partners begin to take action
Flood stage (minor)9.59Apr 9, 2024Minimal or no property damage, but possibly some public threat
Moderate flood stage10.59May 23, 2020Some inundation of structures and roads near the stream
Major flood stage12.06Jul 23, 2017Extensive inundation of structures and roads

Every listed crest

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

Listed crests at the Fox River at Algonquin tailwater, 1938 to 2024 8101214ft Flood stage 9.5 ftMajor 12.0 ft Jul 5, 1938: 14.00 ft, major floodingMar 24, 1948: 12.50 ft, major floodingApr 6, 1960: 13.70 ft, major floodingMar 31, 1962: 12.40 ft, major floodingMay 13, 2010: 10.01 ft, minor flooding; 4,310 cubic feet per secondApr 29, 2011: 9.36 ft, action stage; 3,650 cubic feet per secondApr 23, 2013: 12.70 ft, major flooding; 7,590 cubic feet per secondJun 26, 2013: 11.01 ft, moderate flooding; 5,430 cubic feet per secondJun 25, 2014: 8.93 ft, below flood stage; 3,310 cubic feet per secondApr 7, 2017: 9.29 ft, action stage; 3,660 cubic feet per secondMay 3, 2017: 9.89 ft, minor flooding; 4,250 cubic feet per secondJul 23, 2017: 13.18 ft, major flooding; 7,900 cubic feet per secondFeb 28, 2018: 9.87 ft, minor flooding; 4,120 cubic feet per secondMay 21, 2018: 9.76 ft, minor floodingJun 26, 2018: 11.85 ft, moderate floodingSep 6, 2018: 9.92 ft, minor flooding; 4,160 cubic feet per secondOct 10, 2018: 10.57 ft, moderate flooding; 4,830 cubic feet per secondMar 20, 2019: 10.58 ft, moderate flooding; 4,830 cubic feet per secondMay 12, 2019: 10.55 ft, moderate flooding; 4,760 cubic feet per secondJun 5, 2019: 10.37 ft, minor flooding; 4,620 cubic feet per secondSep 17, 2019: 11.38 ft, moderate flooding; 5,710 cubic feet per secondOct 11, 2019: 10.78 ft, moderate flooding; 5,050 cubic feet per secondOct 31, 2019: 9.54 ft, minor flooding; 3,810 cubic feet per secondMay 3, 2020: 10.55 ft, moderate flooding; 4,800 cubic feet per secondMay 23, 2020: 11.83 ft, moderate flooding; 6,210 cubic feet per secondMar 3, 2023: 9.11 ft, action stage; 3,470 cubic feet per secondApr 4, 2023: 9.58 ft, minor flooding; 3,880 cubic feet per secondApr 9, 2024: 10.42 ft, minor flooding; 4,670 cubic feet per secondJul 18, 2024: 9.43 ft, action stage; 3,750 cubic feet per second Highest, 14.00 ft, Jul 5, 1938 19401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Fox River at Algonquin tailwater 1930s: 1 1940s: 1 1950s: 0 1960s: 2 1970s: 0 1980s: 0 1990s: 0 2000s: 0 2010s: 16 16 2020s: 4 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, Fox River at Algonquin tailwater
1Jul 5, 193814.00+4.50Major—
2Apr 6, 196013.70+4.20Major—
3Jul 23, 201713.18+3.68Major7,900
4Apr 23, 201312.70+3.20Major7,590
5Mar 24, 194812.50+3.00Major—
6Mar 31, 196212.40+2.90Major—
7Jun 26, 201811.85+2.35Moderate—
8May 23, 202011.83+2.33Moderate6,210
9Sep 17, 201911.38+1.88Moderate5,710
10Jun 26, 201311.01+1.51Moderate5,430
11Oct 11, 201910.78+1.28Moderate5,050
12Mar 20, 201910.58+1.08Moderate4,830
13Oct 10, 201810.57+1.07Moderate4,830
14May 12, 201910.55+1.05Moderate4,760
15May 3, 202010.55+1.05Moderate4,800
16Apr 9, 202410.42+0.92Minor4,670
17Jun 5, 201910.37+0.87Minor4,620
18May 13, 201010.01+0.51Minor4,310
19Sep 6, 20189.92+0.42Minor4,160
20May 3, 20179.89+0.39Minor4,250
21Feb 28, 20189.87+0.37Minor4,120
22May 21, 20189.76+0.26Minor—
23Apr 4, 20239.58+0.08Minor3,880
24Oct 31, 20199.54+0.04Minor3,810
25Jul 18, 20249.43−0.07Action3,750
26Apr 29, 20119.36−0.14Action3,650
27Apr 7, 20179.29−0.21Action3,660
28Mar 3, 20239.11−0.39Action3,470
29Jun 25, 20148.93−0.57Below flood stage3,310

The worst floods along the Fox River

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

July 5, 1938: 14.00 ft here, major flooding

April 6, 1960: 13.70 ft here, major flooding

July 23, 2017: 13.18 ft here, major flooding

Gauges on the Fox River

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

Flood gauges on the Fox River
AlgonquinIL3.04.50 ft, Apr 1, 191612
Algonquin tailwater this gaugeIL9.514.00 ft, Jul 5, 19386
BurlingtonWI11.016.15 ft, Jul 13, 20171
DaytonIL12.036.47 ft, Jan 25, 19605
ElginIL713.0713.11 ft, Jul 24, 20170
Fox LakeIL6.08.12 ft, Apr 5, 19606
Lake VillaIL6.08.90 ft, Jul 4, 19387
McHenry (Stratton Lock and Dam) tailwaterIL4.09.00 ft, Jul 5, 19386
MontgomeryIL13.516.50 ft, Jul 18, 19961
RochesterWI6.06.29 ft, Apr 21, 20260
South Elgin DamIL14.515.04 ft, Apr 18, 20130
WaukeshaWI6.08.85 ft, Jun 9, 20080
Yorkville (Palmer Dam)IL15.521.00 ft, Jul 18, 19961
AntiochIL6.08.34 ft, Apr 5, 19606
JohnsburgIL6.58.90 ft, Jul 4, 19382
New MunsterWI11.017.47 ft, Jul 13, 20175

Other gauges in McHenry County

Flood gauges in McHenry County
Mchenry7.07.48 ft, Jun 26, 20130
Algonquin3.04.50 ft, Apr 1, 191612
McHenry (Stratton Lock and Dam) tailwater4.09.00 ft, Jul 5, 19386
Johnsburg6.58.90 ft, Jul 4, 19382
Marengo12.013.06 ft, Sep 4, 20180
Wonder Lake9.014.30 ft, Jun 11, 19671
Spring Grove11.014.26 ft, Sep 26, 19860

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

NOAA National Water Prediction Service, gauge AFBI2, 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.