Observed and urbanization-adjusted annual maximum peak discharge and associated urban fraction and precipitation values at USGS streamgage:
05536215 THORN CREEK AT GLENWOOD, 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 |
| 1950 | 1 | -- | 376 | 0.397 | 1.530 | 780 | 1090 | 0.480 |
| 1951 | 1 | -- | 376 | 0.411 | 2.601 | 831 | 1140 | 0.442 |
| 1952 | 1 | -- | 376 | 0.425 | 1.237 | 780 | 1060 | 0.506 |
| 1953 | 1 | -- | 376 | 0.439 | 2.412 | 848 | 1130 | 0.451 |
| 1954 | 1 | -- | 376 | 0.453 | 1.328 | 729 | 971 | 0.589 |
| 1955 | 1 | -- | 376 | 0.467 | 4.648 | 1180 | 1470 | 0.219 |
| 1956 | 1 | -- | 376 | 0.482 | 1.231 | 830 | 1060 | 0.508 |
| 1957 | 1 | -- | 376 | 0.496 | 2.391 | 2460 | 2880 | 0.022 |
| 1958 | 1 | -- | 376 | 0.510 | 1.707 | 950 | 1170 | 0.421 |
| 1959 | 1 | D | 376 | 0.524 | 1.571 | 1060 | 1270 | 0.340 |
| 1960 | 1 | -- | 376 | 0.538 | 1.049 | 661 | 813 | 0.732 |
| 1961 | 1 | -- | 376 | 0.544 | 2.385 | 1220 | 1420 | 0.245 |
| 1962 | 1 | -- | 376 | 0.550 | 0.705 | 610 | 746 | 0.786 |
| 1963 | 1 | -- | 376 | 0.556 | 1.913 | 528 | 651 | 0.856 |
| 1964 | 1 | -- | 376 | 0.562 | 1.215 | 464 | 577 | 0.904 |
| 1965 | 1 | -- | 376 | 0.568 | 1.233 | 756 | 888 | 0.665 |
| 1966 | 1 | -- | 376 | 0.574 | 2.722 | 1690 | 1890 | 0.098 |
| 1967 | 1 | -- | 376 | 0.580 | 1.402 | 920 | 1050 | 0.515 |
| 1968 | 1 | -- | 376 | 0.586 | 3.148 | 2600 | 2840 | 0.023 |
| 1969 | 1 | -- | 376 | 0.592 | 1.146 | 636 | 736 | 0.793 |
| 1970 | 1 | -- | 376 | 0.598 | 1.419 | 1080 | 1210 | 0.393 |
| 1971 | 1 | -- | 376 | 0.601 | 1.282 | 1010 | 1130 | 0.454 |
| 1972 | 1 | -- | 376 | 0.603 | 2.233 | 905 | 1010 | 0.551 |
| 1973 | 1 | 2 | 376 | 0.606 | 1.179 | 1570 | 1710 | 0.143 |
| 1974 | 1 | -- | 376 | 0.608 | 2.643 | 2300 | 2480 | 0.038 |
| 1975 | 1 | -- | 376 | 0.611 | 1.141 | 715 | 803 | 0.741 |
| 1976 | 1 | D | 376 | 0.613 | 1.599 | 1200 | 1310 | 0.309 |
| 1977 | 1 | -- | 376 | 0.616 | 1.544 | 1180 | 1290 | 0.327 |
| 1978 | 1 | -- | 376 | 0.618 | 1.336 | 1190 | 1290 | 0.322 |
| 1979 | 1 | -- | 376 | 0.621 | 0.464 | 1420 | 1530 | 0.196 |
| 1980 | 1 | -- | 376 | 0.623 | 1.247 | 1180 | 1280 | 0.335 |
| 1981 | 1 | -- | 376 | 0.624 | 2.515 | 2310 | 2460 | 0.040 |
| 1982 | 1 | -- | 376 | 0.624 | 3.967 | 2120 | 2260 | 0.051 |
| 1983 | 1 | -- | 376 | 0.625 | 2.993 | 2210 | 2360 | 0.045 |
| 1984 | 1 | -- | 376 | 0.625 | 1.420 | 1530 | 1640 | 0.164 |
| 1985 | 1 | -- | 376 | 0.626 | 1.160 | 957 | 1040 | 0.526 |
| 1986 | 1 | E | 376 | 0.626 | 1.675 | 1250 | 1350 | 0.286 |
| 1987 | 1 | -- | 376 | 0.627 | 1.461 | 1090 | 1180 | 0.412 |
| 1988 | 1 | E | 376 | 0.627 | 1.071 | 517 | 580 | 0.903 |
| 1989 | 1 | -- | 376 | 0.628 | 2.425 | 1710 | 1830 | 0.114 |
| 1990 | 1 | E | 376 | 0.628 | 1.568 | 1130 | 1220 | 0.381 |
| 1991 | 1 | -- | 376 | 0.629 | 2.032 | 2120 | 2250 | 0.052 |
| 1992 | 1 | CE | 376 | 0.629 | 1.865 | 908 | 986 | 0.574 |
| 1993 | 1 | C | 376 | 0.630 | 0.898 | 1470 | 1570 | 0.184 |
| 1994 | 1 | C | 376 | 0.630 | 2.352 | 1210 | 1300 | 0.317 |
| 1995 | 1 | CE | 376 | 0.631 | 1.339 | 763 | 833 | 0.716 |
| 1996 | 1 | 2C | 376 | 0.631 | 4.574 | 2700 | 2850 | 0.023 |
| 1997 | 1 | CE | 376 | 0.632 | 2.163 | 1370 | 1460 | 0.224 |
| 1998 | 1 | C | 376 | 0.632 | 1.675 | 1180 | 1270 | 0.343 |
| 1999 | 1 | C | 376 | 0.633 | 1.328 | 1100 | 1180 | 0.410 |
| 2000 | 1 | C | 376 | 0.633 | 1.732 | 1050 | 1130 | 0.451 |
| 2001 | 1 | CE | 376 | 0.640 | 1.195 | 692 | 751 | 0.782 |
| 2002 | 1 | CE | 376 | 0.647 | 2.201 | 1290 | 1360 | 0.277 |
| 2003 | 1 | CE | 376 | 0.653 | 2.246 | 1580 | 1650 | 0.161 |
| 2004 | 1 | C | 376 | 0.660 | 1.849 | 867 | 910 | 0.644 |
| 2005 | 1 | C | 376 | 0.667 | 1.184 | 1270 | 1310 | 0.306 |
| 2006 | 1 | C | 376 | 0.674 | 2.386 | 2540 | 2600 | 0.033 |
| 2007 | 1 | C | 376 | 0.681 | 1.219 | 1080 | 1100 | 0.474 |
| 2008 | 1 | C | 376 | 0.687 | 3.675 | 2240 | 2270 | 0.050 |
| 2009 | 1 | C | 376 | 0.694 | 0.646 | 817 | 824 | 0.723 |