Observed and urbanization-adjusted annual maximum peak discharge and associated urban fraction and precipitation values at USGS streamgage:
05542000 MAZON RIVER NEAR COAL CITY, IL
| Water year | Segment | Discharge code | Cumulative reservoir storage (acre-feet) | Urban fraction | Precipitation (inches) | Observed peak discharge (ft3/s) | Adjusted peak discharge (ft3/s) | Exceedance probability |
| 1940 | 1 | -- | 35000 | 0.009 | 1.659 | 1090 | 1120 | 0.989 |
| 1941 | 1 | -- | 35000 | 0.009 | 1.217 | 1820 | 1860 | 0.964 |
| 1942 | 1 | -- | 35000 | 0.010 | 2.415 | 14000 | 14100 | 0.175 |
| 1943 | 1 | -- | 35000 | 0.010 | 1.439 | 13600 | 13700 | 0.187 |
| 1944 | 1 | -- | 35000 | 0.010 | 1.373 | 13700 | 13800 | 0.184 |
| 1945 | 1 | -- | 35000 | 0.010 | 1.391 | 7900 | 8000 | 0.531 |
| 1946 | 1 | -- | 35000 | 0.010 | 2.280 | 11600 | 11700 | 0.277 |
| 1947 | 1 | -- | 35000 | 0.010 | 2.203 | 12500 | 12600 | 0.231 |
| 1948 | 1 | -- | 35000 | 0.010 | 1.175 | 8120 | 8220 | 0.510 |
| 1949 | 1 | -- | 35000 | 0.010 | 0.801 | 7340 | 7430 | 0.587 |
| 1950 | 1 | -- | 35000 | 0.011 | 1.668 | 17300 | 17500 | 0.093 |
| 1951 | 1 | D | 35000 | 0.011 | 0.374 | 11100 | 11200 | 0.304 |
| 1952 | 1 | -- | 35000 | 0.011 | 0.826 | 5880 | 5960 | 0.712 |
| 1953 | 1 | -- | 35000 | 0.011 | 0.548 | 5180 | 5250 | 0.770 |
| 1954 | 1 | -- | 35000 | 0.011 | 1.849 | 10300 | 10400 | 0.350 |
| 1955 | 1 | E | 35000 | 0.011 | 0.759 | 3760 | 3810 | 0.874 |
| 1956 | 1 | E | 35000 | 0.012 | 0.328 | 2070 | 2110 | 0.956 |
| 1957 | 1 | -- | 35000 | 0.012 | 0.392 | 7800 | 7880 | 0.542 |
| 1958 | 1 | -- | 35000 | 0.012 | 1.342 | 17600 | 17700 | 0.089 |
| 1959 | 1 | -- | 35000 | 0.012 | 1.201 | 8200 | 8280 | 0.505 |
| 1960 | 1 | -- | 35000 | 0.012 | 0.963 | 5800 | 5860 | 0.720 |
| 1961 | 1 | E | 35000 | 0.013 | 1.579 | 5500 | 5560 | 0.746 |
| 1962 | 1 | -- | 35000 | 0.013 | 0.318 | 7010 | 7080 | 0.618 |
| 1963 | 1 | E | 35000 | 0.013 | 0.533 | 3680 | 3730 | 0.879 |
| 1964 | 1 | E | 35000 | 0.013 | 1.113 | 1200 | 1220 | 0.986 |
| 1965 | 1 | -- | 35000 | 0.013 | 1.124 | 9390 | 9470 | 0.410 |
| 1966 | 1 | -- | 35000 | 0.013 | 1.477 | 8650 | 8730 | 0.467 |
| 1967 | 1 | -- | 35000 | 0.013 | 1.049 | 7710 | 7780 | 0.552 |
| 1968 | 1 | -- | 35000 | 0.013 | 1.977 | 16800 | 16900 | 0.102 |
| 1969 | 1 | E | 35000 | 0.013 | 1.174 | 4470 | 4520 | 0.825 |
| 1970 | 1 | E | 35000 | 0.014 | 1.705 | 16800 | 16900 | 0.102 |
| 1971 | 1 | -- | 35000 | 0.014 | 0.431 | 4750 | 4800 | 0.804 |
| 1972 | 1 | -- | 35000 | 0.014 | 1.104 | 8000 | 8060 | 0.525 |
| 1973 | 1 | -- | 35000 | 0.014 | 0.738 | 12000 | 12100 | 0.258 |
| 1974 | 1 | -- | 35000 | 0.014 | 1.081 | 9250 | 9320 | 0.421 |
| 1975 | 1 | -- | 35000 | 0.015 | 1.137 | 7080 | 7130 | 0.613 |
| 1976 | 1 | -- | 35000 | 0.015 | 0.926 | 8340 | 8400 | 0.494 |
| 1977 | 1 | -- | 35000 | 0.015 | 1.469 | 4670 | 4710 | 0.810 |
| 1978 | 1 | -- | 35000 | 0.015 | 1.007 | 5560 | 5600 | 0.743 |
| 1979 | 1 | -- | 35000 | 0.015 | 1.376 | 13300 | 13400 | 0.198 |
| 1980 | 1 | -- | 35000 | 0.016 | 1.051 | 12200 | 12300 | 0.249 |
| 1981 | 1 | -- | 35000 | 0.016 | 1.621 | 9970 | 10000 | 0.373 |
| 1982 | 1 | -- | 35000 | 0.016 | 0.342 | 10200 | 10300 | 0.359 |
| 1983 | 1 | -- | 35000 | 0.016 | 2.218 | 22400 | 22500 | 0.046 |
| 1984 | 1 | -- | 35000 | 0.016 | 0.626 | 16800 | 16900 | 0.103 |
| 1985 | 1 | -- | 35000 | 0.016 | 0.778 | 18800 | 18900 | 0.074 |
| 1986 | 1 | -- | 35000 | 0.016 | 1.069 | 16800 | 16900 | 0.103 |
| 1987 | 1 | -- | 35000 | 0.016 | 1.578 | 9310 | 9360 | 0.418 |
| 1988 | 1 | E | 35000 | 0.016 | 0.468 | 4610 | 4640 | 0.816 |
| 1989 | 1 | -- | 35000 | 0.016 | 2.141 | 11400 | 11500 | 0.291 |
| 1990 | 1 | -- | 35000 | 0.017 | 0.572 | 10500 | 10500 | 0.342 |
| 1991 | 1 | -- | 35000 | 0.017 | 1.410 | 20800 | 20900 | 0.057 |
| 1992 | 1 | E | 35000 | 0.017 | 0.731 | 3040 | 3060 | 0.917 |
| 1993 | 1 | -- | 35000 | 0.017 | 1.875 | 10700 | 10700 | 0.331 |
| 1994 | 1 | E | 35000 | 0.017 | 1.809 | 9150 | 9190 | 0.431 |
| 1995 | 1 | -- | 35000 | 0.017 | 1.501 | 8140 | 8170 | 0.515 |
| 1997 | 1 | -- | 35000 | 0.018 | 1.750 | 13500 | 13500 | 0.193 |
| 1998 | 1 | -- | 35000 | 0.018 | 1.444 | 16600 | 16600 | 0.109 |
| 1999 | 1 | -- | 35000 | 0.018 | 1.360 | 10200 | 10200 | 0.361 |
| 2000 | 1 | E | 35000 | 0.018 | 1.213 | 3830 | 3850 | 0.872 |
| 2001 | 1 | -- | 35000 | 0.019 | 0.676 | 12600 | 12600 | 0.231 |
| 2002 | 1 | -- | 35000 | 0.019 | 1.903 | 14100 | 14100 | 0.175 |
| 2003 | 1 | E | 35000 | 0.019 | 1.726 | 8220 | 8240 | 0.509 |
| 2004 | 1 | E | 35000 | 0.019 | 2.121 | 8520 | 8540 | 0.483 |
| 2005 | 1 | -- | 35000 | 0.020 | 1.186 | 14300 | 14300 | 0.170 |
| 2006 | 1 | -- | 35000 | 0.020 | 1.087 | 3170 | 3180 | 0.910 |
| 2007 | 1 | -- | 35000 | 0.020 | 2.045 | 12300 | 12300 | 0.247 |
| 2008 | 1 | -- | 35000 | 0.021 | 2.517 | 18800 | 18800 | 0.074 |
| 2009 | 1 | -- | 35000 | 0.021 | 1.917 | 14000 | 14000 | 0.179 |