Observed and urbanization-adjusted annual maximum peak discharge and associated urban fraction and precipitation values at USGS streamgage:
05447000 GREEN RIVER AT AMBOY, 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 | -- | 0 | 0.005 | 0.532 | 2030 | 2040 | 0.685 |
| 1941 | 1 | -- | 0 | 0.005 | 0.577 | 2490 | 2510 | 0.563 |
| 1942 | 1 | -- | 0 | 0.005 | 1.608 | 2230 | 2240 | 0.634 |
| 1943 | 1 | -- | 0 | 0.005 | 0.678 | 2680 | 2700 | 0.507 |
| 1944 | 1 | -- | 0 | 0.005 | 1.379 | 2820 | 2840 | 0.471 |
| 1945 | 1 | -- | 0 | 0.005 | 1.017 | 2100 | 2110 | 0.666 |
| 1946 | 1 | -- | 0 | 0.005 | 0.634 | 3960 | 3980 | 0.254 |
| 1947 | 1 | -- | 0 | 0.005 | 0.966 | 2020 | 2030 | 0.688 |
| 1948 | 1 | -- | 0 | 0.005 | 1.829 | 3030 | 3050 | 0.421 |
| 1949 | 1 | -- | 0 | 0.005 | 0.170 | 2890 | 2910 | 0.454 |
| 1950 | 1 | -- | 0 | 0.005 | 1.388 | 2890 | 2910 | 0.454 |
| 1951 | 1 | -- | 0 | 0.005 | 0.350 | 2770 | 2790 | 0.483 |
| 1952 | 1 | -- | 0 | 0.005 | 0.487 | 2560 | 2570 | 0.542 |
| 1953 | 1 | -- | 0 | 0.006 | 0.890 | 615 | 621 | 0.962 |
| 1954 | 1 | -- | 0 | 0.006 | 1.577 | 1350 | 1360 | 0.848 |
| 1955 | 1 | -- | 0 | 0.006 | 3.197 | 6120 | 6150 | 0.074 |
| 1956 | 1 | -- | 0 | 0.006 | 0.478 | 1790 | 1800 | 0.750 |
| 1957 | 1 | -- | 0 | 0.006 | 0.417 | 593 | 598 | 0.965 |
| 1958 | 1 | -- | 0 | 0.006 | 1.312 | 1910 | 1920 | 0.717 |
| 1959 | 1 | -- | 0 | 0.006 | 1.715 | 3740 | 3760 | 0.289 |
| 1960 | 1 | -- | 62 | 0.006 | 0.526 | 4240 | 4260 | 0.213 |
| 1961 | 1 | -- | 62 | 0.006 | 2.410 | 480 | 485 | 0.979 |
| 1962 | 1 | -- | 62 | 0.006 | 0.344 | 3280 | 3300 | 0.370 |
| 1963 | 1 | -- | 62 | 0.006 | 0.398 | 2220 | 2230 | 0.636 |
| 1964 | 1 | -- | 62 | 0.006 | 1.121 | 1030 | 1040 | 0.909 |
| 1965 | 1 | -- | 62 | 0.006 | 0.900 | 3290 | 3310 | 0.368 |
| 1966 | 1 | -- | 62 | 0.006 | 1.846 | 4600 | 4620 | 0.176 |
| 1967 | 1 | -- | 62 | 0.006 | 1.351 | 2530 | 2540 | 0.551 |
| 1968 | 1 | 4B | 62 | 0.006 | 0.004 | 502 | 507 | 0.976 |
| 1969 | 1 | -- | 62 | 0.006 | 0.184 | 4110 | 4130 | 0.232 |
| 1970 | 1 | -- | 62 | 0.006 | 1.673 | 4130 | 4150 | 0.229 |
| 1971 | 1 | -- | 62 | 0.006 | 0.374 | 3600 | 3620 | 0.312 |
| 1972 | 1 | -- | 62 | 0.006 | 1.450 | 4260 | 4280 | 0.210 |
| 1973 | 1 | -- | 62 | 0.006 | 1.400 | 4460 | 4480 | 0.188 |
| 1974 | 1 | -- | 62 | 0.007 | 1.874 | 5010 | 5030 | 0.141 |
| 1975 | 1 | -- | 62 | 0.007 | 0.004 | 2740 | 2750 | 0.492 |
| 1976 | 1 | -- | 62 | 0.007 | 1.275 | 2410 | 2420 | 0.589 |
| 1978 | 1 | -- | 62 | 0.007 | 1.995 | 4740 | 4750 | 0.164 |
| 1979 | 1 | -- | 62 | 0.007 | 0.323 | 5750 | 5770 | 0.091 |
| 1980 | 1 | 2 | 62 | 0.008 | 0.321 | 950 | 955 | 0.923 |
| 1981 | 1 | -- | 62 | 0.008 | 1.905 | 7600 | 7620 | 0.042 |
| 1982 | 1 | -- | 62 | 0.008 | 1.585 | 3530 | 3540 | 0.326 |