| 44.1 | This level is estimated to be met or exceeded on average once every 500 years. |
| 42.7 | This is the RECORD FLOOD LEVEL that was reached on August 1 1993. |
| 42.6 | This level is expected to be met or exceeded on average once every 200 years. |
| 40.0 | Railroad tracks from Wood River to Alton begin to flood. |
| 39.8 | This level is estimated to be met or exceeded on average once every 100 years. |
| 39.0 | US Highway 67 floods from Wood River to Alton. |
| 38.6 | Flood waters reach the low steel on RR bridge swing span in Alton. |
| 37.8 | This level is estimated to be met or exceeded on average once every 50 years. |
| 37.6 | Damage begins to Miller Milling Company in Alton |
| 36.6 | Urban flood damage begins in Winfield. |
| 35.3 | This level is estimated to be met or exceeded on average once every 25 years. |
| 35.0 | Burlington Northern RR floods from West Alton, Missouri to Alton, Illinois. |
| 34.3 | This level is estimated to be met or exceeded on average once every 20 years. |
| 34.0 | Major damage level. Commercial damages begin in Alton. |
| 33.5 | Urban flood damage begins in Alton at Riverfront Park. |
| 33.0 | Urban flood damage begins in Elsah, Illinois and Portage des Sioux. |
| 31.5 | Commercial basements in Alton begin to flood. |
| 31.4 | This level is estimated to be met or exceeded on average once every 10 years. |
| 29.9 | Route 100 at Alton closes. Also at this level the north and south Wood River Levee structures are closed. |
| 29.5 | Urban flood damage begins in Peruque. |
| 29.3 | The North Wood River Levee must be closed at this level. |
| 29.0 | Moderate flooding begins. |
| 28.8 | This level is estimated to be met or exceeded on average once every 5 years. |
| 28.5 | The South Wood River Levee must be closed at this level. |
| 26.5 | Highway 94 floods from Portage des Sioux to West Alton. |
| 25.5 | Urban damage begins in Kampsville Illinois. |
| 24.3 | This level is estimated to be met or exceeded on average once every 2 years. |
| 21.0 | Flood Stage. Minor flooding begins to occur at this level. |
| 20.8 | Unprotected farm land begins to flood |
