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Mazon River near Coal City

Highest listed crest 21.00 ftFlood stage 12.0 ft72 crests since 1924

The Mazon River near Coal City crested at major flood stage 3 times among the 72 crests the National Weather Service lists from 1924 to 2021. The highest, 21.00 ft on August 8, 1924, was major flooding, 9.00 feet above flood stage.

The gauge

Highest listed crest
21.00 ft
August 8, 1924
Flood stage
12.0 ft
Major flooding from 19.0 ft
Crests at major
3
72nd of 177 gauges in Illinois
Most recent flood crest
May 18, 2020
17.88 ft, moderate flooding
Location
Grundy County
Near Morris (7.3 mi), Channahon (10.7 mi), Minooka (12.1 mi)

Flood stages

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

Flood categories, Mazon River near Coal City
Action stage10.019Jun 28, 2021The level at which the NWS or its partners begin to take action
Flood stage (minor)12.030Apr 30, 2020Minimal or no property damage, but possibly some public threat
Moderate flood stage16.016May 18, 2020Some inundation of structures and roads near the stream
Major flood stage19.03Dec 4, 1982Extensive inundation of structures and roads

Every listed crest

72 crests from 1924 to 2021. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Mazon River near Coal City, 1924 to 2021 510152025ft Flood stage 12.0 ftMajor 19.0 ft Aug 8, 1924: 21.00 ft, major floodingFeb 7, 1942: 17.28 ft, moderate flooding; 14,000 cubic feet per secondMay 12, 1943: 16.13 ft, moderate flooding; 13,600 cubic feet per secondApr 23, 1944: 16.22 ft, moderate flooding; 13,700 cubic feet per secondMay 15, 1945: 12.01 ft, minor flooding; 7,900 cubic feet per secondJun 13, 1946: 14.76 ft, minor flooding; 11,600 cubic feet per secondApr 5, 1947: 15.31 ft, minor flooding; 12,500 cubic feet per secondMar 19, 1948: 11.84 ft, action stage; 8,120 cubic feet per secondFeb 13, 1949: 11.20 ft, action stage; 7,340 cubic feet per secondApr 25, 1950: 18.50 ft, moderate flooding; 17,300 cubic feet per secondFeb 19, 1951: 14.11 ft, minor flooding; 11,100 cubic feet per secondNov 14, 1951: 9.97 ft, below flood stage; 5,880 cubic feet per secondMar 13, 1953: 9.37 ft, below flood stage; 5,180 cubic feet per secondMar 25, 1954: 13.48 ft, minor flooding; 10,300 cubic feet per secondJun 19, 1957: 12.64 ft, minor flooding; 7,800 cubic feet per secondJul 15, 1958: 19.70 ft, major flooding; 17,600 cubic feet per secondApr 28, 1959: 13.04 ft, minor flooding; 8,200 cubic feet per secondJun 14, 1960: 10.58 ft, action stage; 5,800 cubic feet per secondSep 26, 1961: 10.33 ft, action stage; 5,500 cubic feet per secondMar 12, 1962: 11.20 ft, action stage; 7,010 cubic feet per secondMay 5, 1965: 13.03 ft, minor flooding; 9,390 cubic feet per secondMay 12, 1966: 12.46 ft, minor flooding; 8,650 cubic feet per secondApr 2, 1967: 11.74 ft, action stage; 7,710 cubic feet per secondJun 26, 1968: 18.11 ft, moderate flooding; 16,800 cubic feet per secondMay 15, 1970: 18.15 ft, moderate flooding; 16,800 cubic feet per secondMar 15, 1971: 9.34 ft, below flood stage; 4,750 cubic feet per secondAug 8, 1972: 11.96 ft, action stage; 8,000 cubic feet per secondDec 31, 1972: 14.88 ft, minor flooding; 12,000 cubic feet per secondJun 23, 1974: 12.92 ft, minor flooding; 9,250 cubic feet per secondJun 16, 1975: 11.36 ft, action stage; 7,080 cubic feet per secondMar 5, 1976: 12.34 ft, minor flooding; 8,340 cubic feet per secondSep 2, 1977: 9.19 ft, below flood stage; 4,670 cubic feet per secondSep 19, 1978: 10.06 ft, action stage; 5,560 cubic feet per secondApr 12, 1979: 16.19 ft, moderate flooding; 13,300 cubic feet per secondJun 2, 1980: 15.37 ft, minor flooding; 12,200 cubic feet per secondJun 14, 1981: 13.64 ft, minor flooding; 9,970 cubic feet per secondMar 12, 1982: 13.79 ft, minor flooding; 10,200 cubic feet per secondDec 4, 1982: 19.51 ft, major flooding; 22,400 cubic feet per secondFeb 13, 1984: 16.82 ft, moderate flooding; 16,800 cubic feet per secondFeb 24, 1985: 17.80 ft, moderate flooding; 18,800 cubic feet per secondNov 19, 1985: 16.75 ft, moderate flooding; 16,800 cubic feet per secondOct 4, 1986: 12.34 ft, minor flooding; 9,310 cubic feet per secondSep 2, 1989: 15.17 ft, minor flooding; 11,400 cubic feet per secondMar 11, 1990: 14.45 ft, minor flooding; 10,500 cubic feet per secondNov 28, 1990: 18.83 ft, moderate flooding; 20,800 cubic feet per secondSep 15, 1993: 12.85 ft, minor flooding; 10,700 cubic feet per secondOct 18, 1993: 11.79 ft, action stage; 9,150 cubic feet per secondJun 14, 1999: 12.56 ft, minor flooding; 10,200 cubic feet per secondMay 13, 2002: 15.02 ft, minor flooding; 14,400 cubic feet per secondJul 19, 2003: 11.11 ft, action stage; 8,220 cubic feet per secondMay 31, 2004: 11.35 ft, action stage; 8,520 cubic feet per secondJan 14, 2005: 15.22 ft, minor flooding; 14,300 cubic feet per secondAug 25, 2007: 13.83 ft, minor flooding; 11,700 cubic feet per secondSep 15, 2008: 18.54 ft, moderate flooding; 18,500 cubic feet per secondMar 9, 2009: 15.80 ft, minor flooding; 14,000 cubic feet per secondOct 31, 2009: 11.95 ft, action stage; 8,320 cubic feet per secondMay 26, 2011: 11.50 ft, action stage; 8,720 cubic feet per secondMay 8, 2012: 15.48 ft, minor flooding; 14,500 cubic feet per secondMar 11, 2013: 10.23 ft, action stage; 6,770 cubic feet per secondApr 18, 2013: 18.00 ft, moderate flooding; 19,000 cubic feet per secondAug 23, 2014: 12.32 ft, minor flooding; 9,540 cubic feet per secondJun 23, 2015: 12.26 ft, minor flooding; 8,760 cubic feet per secondJun 27, 2015: 11.75 ft, action stage; 8,030 cubic feet per secondDec 29, 2015: 16.40 ft, moderate flooding; 15,900 cubic feet per secondJul 19, 2016: 13.78 ft, minor flooding; 11,500 cubic feet per secondAug 29, 2016: 11.57 ft, action stage; 8,340 cubic feet per secondMay 1, 2017: 11.35 ft, action stage; 8,050 cubic feet per secondFeb 21, 2018: 12.87 ft, minor flooding; 10,200 cubic feet per secondMay 1, 2019: 16.41 ft, moderate flooding; 15,900 cubic feet per secondApr 30, 2020: 13.04 ft, minor flooding; 10,400 cubic feet per secondMay 18, 2020: 17.88 ft, moderate flooding; 18,700 cubic feet per secondJun 28, 2021: 10.81 ft, action stage; 7,350 cubic feet per second Highest, 21.00 ft, Aug 8, 1924 19401960198020002020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Mazon River near Coal City 1920s: 1 1930s: 0 1940s: 6 1950s: 6 1960s: 3 1970s: 5 1980s: 9 9 1990s: 4 2000s: 5 2010s: 8 2020s: 2 1920s1930s1940s1950s1960s1970s1980s1990s2000s2010s2020s
  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

The 50 highest of 72 listed crests.

Highest listed crests, Mazon River near Coal City
1Aug 8, 192421.00+9.00Major—
2Jul 15, 195819.70+7.70Major17,600
3Dec 4, 198219.51+7.51Major22,400
4Nov 28, 199018.83+6.83Moderate20,800
5Sep 15, 200818.54+6.54Moderate18,500
6Apr 25, 195018.50+6.50Moderate17,300
7May 15, 197018.15+6.15Moderate16,800
8Jun 26, 196818.11+6.11Moderate16,800
9Apr 18, 201318.00+6.00Moderate19,000
10May 18, 202017.88+5.88Moderate18,700
11Feb 24, 198517.80+5.80Moderate18,800
12Feb 7, 194217.28+5.28Moderate14,000
13Feb 13, 198416.82+4.82Moderate16,800
14Nov 19, 198516.75+4.75Moderate16,800
15May 1, 201916.41+4.41Moderate15,900
16Dec 29, 201516.40+4.40Moderate15,900
17Apr 23, 194416.22+4.22Moderate13,700
18Apr 12, 197916.19+4.19Moderate13,300
19May 12, 194316.13+4.13Moderate13,600
20Mar 9, 200915.80+3.80Minor14,000
21May 8, 201215.48+3.48Minor14,500
22Jun 2, 198015.37+3.37Minor12,200
23Apr 5, 194715.31+3.31Minor12,500
24Jan 14, 200515.22+3.22Minor14,300
25Sep 2, 198915.17+3.17Minor11,400
26May 13, 200215.02+3.02Minor14,400
27Dec 31, 197214.88+2.88Minor12,000
28Jun 13, 194614.76+2.76Minor11,600
29Mar 11, 199014.45+2.45Minor10,500
30Feb 19, 195114.11+2.11Minor11,100
31Aug 25, 200713.83+1.83Minor11,700
32Mar 12, 198213.79+1.79Minor10,200
33Jul 19, 201613.78+1.78Minor11,500
34Jun 14, 198113.64+1.64Minor9,970
35Mar 25, 195413.48+1.48Minor10,300
36Apr 28, 195913.04+1.04Minor8,200
37Apr 30, 202013.04+1.04Minor10,400
38May 5, 196513.03+1.03Minor9,390
39Jun 23, 197412.92+0.92Minor9,250
40Feb 21, 201812.87+0.87Minor10,200
41Sep 15, 199312.85+0.85Minor10,700
42Jun 19, 195712.64+0.64Minor7,800
43Jun 14, 199912.56+0.56Minor10,200
44May 12, 196612.46+0.46Minor8,650
45Mar 5, 197612.34+0.34Minor8,340
46Oct 4, 198612.34+0.34Minor9,310
47Aug 23, 201412.32+0.32Minor9,540
48Jun 23, 201512.26+0.26Minor8,760
49May 15, 194512.01+0.01Minor7,900
50Aug 8, 197211.96−0.04Action8,000

Other gauges in Grundy County

Flood gauges in Grundy County
Morris11.014.52 ft, Aug 24, 20071
Morris16.024.91 ft, Apr 19, 201312
Lorenzo508.0508.54 ft, May 18, 20200

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

NOAA National Water Prediction Service, gauge COLI2, 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.