Mazon River near Coal City, IL
River level and flood forecast · Grundy County
Normal1.5 ftas of Mon 2:45 PM
The river is 10.5 ft below flood stage (12 ft).
Flow: 46 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Sun, Dec 31, 6 PM. Forecasts change as rain falls and as upstream water arrives.
Flood stages
| Major flood stage | 19 ft |
| Moderate flood stage | 16 ft |
| Flood stage | 12 ft |
| Action stage | 10 ft |
| Record crest (August 8, 1924) | 21 ft |
What floods at each level
From the National Weather Service, highest first.
- 24 ftResidential structures may be threatened along Forest Drive and West Avenue west of Coal City.
- 22 ftStructures may be threatened along Spring Road west of Coal City. Whitetie Road may be threatened west of Coal City.
- 20 ftIL-113, Pine Bluff Road, and McArdle Road may be threatened west of Coal City. Reed Road may be threatened southwest of Coal City.
- 18 ftSpring Road may be threatened west of Coal City.
- 16 ftGorman Road and Grand Ridge Road may be threatened southwest of Coal City. Widespread inundation of agricultural land occurs.
- 15 ftWater may begin to overflow into nearby lakes along the river.
- 12 ftLow-lying agricultural land is inundated west of Coal City.
- 10 ftLow-lying agricultural land is inundated northwest of Coal City near the Illinois River.
- 8 ftWater overtops low-lying banks along the river west of Coal City.
Highest crests on record
- 21 ft — August 8, 1924
- 19.7 ft — July 15, 1958
- 19.51 ft — December 4, 1982
- 18.83 ft — November 28, 1990
- 18.54 ft — September 15, 2008
Recent crests: 10.81 ft (June 28, 2021) · 17.88 ft (May 18, 2020) · 13.04 ft (April 30, 2020) · 16.41 ft (May 1, 2019) · 12.87 ft (February 21, 2018)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (COLI2); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.