Observed and urbanization-adjusted annual maximum peak discharge and associated urban fraction and precipitation values at USGS streamgage:
05536000 NORTH BRANCH CHICAGO RIVER AT NILES, 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 |
| 1951 | 1 | -- | 0 | 0.351 | 1.682 | 952 | 1490 | 0.414 |
| 1952 | 1 | -- | 0 | 0.371 | 0.981 | 870 | 1360 | 0.503 |
| 1953 | 1 | E | 0 | 0.390 | 0.756 | 428 | 790 | 0.898 |
| 1954 | 1 | -- | 0 | 0.410 | 1.521 | 1510 | 2070 | 0.154 |
| 1955 | 1 | -- | 0 | 0.429 | 2.850 | 1700 | 2270 | 0.110 |
| 1956 | 1 | -- | 0 | 0.449 | 1.255 | 1030 | 1460 | 0.436 |
| 1957 | 1 | -- | 0 | 0.468 | 2.133 | 1850 | 2380 | 0.092 |
| 1958 | 1 | -- | 0 | 0.488 | 0.180 | 647 | 957 | 0.798 |
| 1959 | 1 | -- | 0 | 0.507 | 1.144 | 695 | 992 | 0.774 |
| 1960 | 1 | -- | 0 | 0.527 | 0.382 | 1340 | 1690 | 0.285 |
| 1961 | 1 | -- | 0 | 0.538 | 1.405 | 1290 | 1620 | 0.326 |
| 1962 | 1 | -- | 0 | 0.550 | 0.228 | 1010 | 1290 | 0.548 |
| 1963 | 1 | E | 0 | 0.561 | 1.112 | 905 | 1160 | 0.648 |
| 1964 | 1 | -- | 0 | 0.573 | 0.879 | 810 | 1050 | 0.737 |
| 1965 | 1 | -- | 0 | 0.584 | 0.717 | 658 | 872 | 0.850 |
| 1966 | 1 | -- | 0 | 0.596 | 1.323 | 1360 | 1610 | 0.331 |
| 1967 | 1 | -- | 0 | 0.608 | 1.651 | 2210 | 2500 | 0.075 |
| 1968 | 1 | -- | 0 | 0.619 | 1.209 | 858 | 1050 | 0.738 |
| 1969 | 1 | -- | 0 | 0.631 | 1.648 | 1300 | 1500 | 0.407 |
| 1970 | 0 | -- | 961 | 0.642 | 1.525 | 1170 | 1370 | 0.495 |
| 1971 | 0 | D | 961 | 0.648 | 0.378 | 1070 | 1280 | 0.561 |
| 1972 | 0 | -- | 961 | 0.653 | 1.451 | 1440 | 1690 | 0.281 |
| 1973 | 0 | -- | 1561 | 0.659 | 1.213 | 1050 | 1280 | 0.555 |
| 1974 | 2 | -- | 1561 | 0.664 | 1.084 | 1070 | 1320 | 0.528 |
| 1975 | 2 | -- | 1561 | 0.670 | 0.845 | 1160 | 1420 | 0.462 |
| 1976 | 2 | D | 1561 | 0.675 | 1.360 | 1550 | 1840 | 0.216 |
| 1977 | 2 | E | 1561 | 0.681 | 0.811 | 723 | 913 | 0.826 |
| 1978 | 2 | -- | 1561 | 0.686 | 1.028 | 1150 | 1380 | 0.486 |
| 1979 | 0 | -- | 2961 | 0.692 | 0.819 | 1150 | 1380 | 0.488 |
| 1980 | 3 | -- | 2961 | 0.697 | 0.814 | 712 | 889 | 0.840 |
| 1981 | 3 | -- | 2961 | 0.701 | 0.932 | 1160 | 1390 | 0.485 |
| 1982 | 3 | -- | 2961 | 0.704 | 2.568 | 1420 | 1670 | 0.294 |
| 1983 | 3 | -- | 2961 | 0.708 | 1.844 | 1480 | 1720 | 0.263 |
| 1984 | 3 | -- | 2961 | 0.711 | 1.772 | 1210 | 1430 | 0.456 |
| 1985 | 3 | -- | 2961 | 0.714 | 1.119 | 1350 | 1580 | 0.354 |
| 1986 | 3 | -- | 2961 | 0.718 | 1.073 | 1800 | 2060 | 0.156 |
| 1987 | 3 | -- | 2961 | 0.721 | 4.025 | 2590 | 2930 | 0.043 |
| 1988 | 3 | E | 2961 | 0.724 | 0.445 | 831 | 989 | 0.776 |
| 1989 | 3 | -- | 2961 | 0.728 | 2.199 | 1780 | 2020 | 0.166 |
| 1990 | 3 | -- | 3846 | 0.731 | 1.842 | 1600 | 1820 | 0.224 |
| 1991 | 3 | -- | 3846 | 0.734 | 2.258 | 1360 | 1560 | 0.369 |
| 1992 | 0 | CE | 4921 | 0.738 | 2.125 | 893 | 1020 | 0.753 |
| 1993 | 4 | C | 4921 | 0.741 | 1.003 | 1250 | 1380 | 0.488 |
| 1994 | 4 | C | 4921 | 0.745 | 2.012 | 1530 | 1670 | 0.292 |
| 1995 | 4 | CE | 4921 | 0.748 | 1.320 | 1330 | 1460 | 0.437 |
| 1996 | 4 | C | 4921 | 0.752 | 0.805 | 1220 | 1340 | 0.520 |
| 1997 | 4 | C | 4921 | 0.755 | 2.793 | 2260 | 2420 | 0.087 |
| 1998 | 4 | C | 4921 | 0.759 | 1.091 | 993 | 1090 | 0.710 |
| 1999 | 4 | C | 4921 | 0.762 | 1.312 | 1800 | 1920 | 0.191 |
| 2000 | 4 | CE | 4921 | 0.765 | 1.696 | 1290 | 1390 | 0.483 |
| 2001 | 4 | C | 4921 | 0.772 | 0.686 | 1380 | 1470 | 0.427 |
| 2002 | 4 | C | 4921 | 0.779 | 3.132 | 1940 | 2040 | 0.163 |
| 2003 | 4 | C | 4921 | 0.785 | 1.364 | 1130 | 1190 | 0.623 |
| 2004 | 4 | CE | 4921 | 0.792 | 1.197 | 1130 | 1180 | 0.631 |
| 2005 | 4 | CE | 4921 | 0.798 | 0.701 | 1210 | 1260 | 0.575 |
| 2006 | 4 | C | 4921 | 0.805 | 0.753 | 965 | 999 | 0.769 |
| 2007 | 4 | C | 4921 | 0.812 | 1.465 | 1730 | 1760 | 0.245 |
| 2008 | 4 | C | 4921 | 0.818 | 4.229 | 3340 | 3370 | 0.026 |
| 2009 | 4 | C | 4921 | 0.825 | 2.137 | 1980 | 1990 | 0.174 |