| Station: | Alton, Illinois | Continent: | North America | ||
| River: | Mississippi | Major Basin : | Gulf of Mexico | ||
| Country: | United States | Discharge into : | Atlantic Ocean | ||
| Observation Period: | 1927 - 1984 | Total Months: | 675 | ||
| Latitude (dec deg): | 38.88 N | Area (km2): | 444185 | ||
| Longitude (dec deg): | 90.16 W | Elevation (m): | 0 | ||
| Annual Discharge: (m3/s): | 2891.2 | (km3/yr): | 91.3 | ||
| Annual Runoff: (l/s/km2): | 6.5 | (mm/yr): | 205.6 |
| Mean for Observation Period | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
| m3/sec | 1899.1 | 2310.0 | 3866.0 | 5356.8 | 4801.3 | 3937.4 | 3107.1 | 1922.5 | 1815.7 | 1866.8 | 2014.4 | 1847.7 |
| km3/mo | 5.1 | 5.6 | 10.4 | 13.9 | 12.9 | 10.2 | 8.3 | 5.1 | 4.7 | 5.0 | 5.2 | 4.9 |
| mm/mo | 11.5 | 12.6 | 23.3 | 31.3 | 29.0 | 23.0 | 18.7 | 11.6 | 10.6 | 11.3 | 11.8 | 11.1 |
| l/s/km2 | 4.3 | 5.2 | 8.7 | 12.1 | 10.8 | 8.9 | 7.0 | 4.3 | 4.1 | 4.2 | 4.5 | 4.2 |
