Provisional Monthly Streamflow Network - Tabular Data: September 2025
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Long-term monthly flows for period of record (cfs) | ||||||||
| Station | Drainage area (sq. mi.) |
Years of record | Monthly mean flow (cfs) | Mean flow* | Median (50% exceedence) flow | 90% exceedence flow | 10% exceedence flow | USGS Station No. |
| Rock River at Rockton |
6,363 |
85 |
3,901 |
3,349 |
2,802 |
1,166 |
7,026 |
|
| Rock River near Joslin |
9,549 |
85 |
5,117 |
4,891 |
4,077 |
1,784 |
9,387 |
|
| Pecatonica River at Freeport |
1,326 |
110 |
849 |
836 |
679 |
329 |
1,467 |
|
| Green River near Geneseo |
1,003 |
89 |
110 |
372 |
180 |
61 |
1,048 |
|
| Edwards River near New Boston |
445 |
90 |
42 |
140 |
53 |
18 |
369 |
|
| Kankakee River at Momence |
2,294 |
111 |
944 |
1,082 |
830 |
553 |
1,945 |
|
| Iroquois River near Chebanse |
2,091 |
102 |
90 |
586 |
128 |
45 |
1,814 |
|
| Fox River at Dayton |
2,642 |
110 |
876 |
1,116 |
755 |
275 |
2,673 |
|
| Vermilion River at Pontiac |
579 |
82 |
1 |
126 |
18 |
2 |
616 |
|
| Spoon River at Seville |
1,636 |
111 |
84 |
583 |
201 |
59 |
1,380 |
|
| LaMoine River at Ripley |
1,293 |
104 |
28 |
447 |
120 |
26 |
1,172 |
|
| Bear Creek near Marcelline |
349 |
81 |
1 |
146 |
19 |
1 |
449 |
|
| Mackinaw River near Congerville |
767 |
80 |
6 |
222 |
28 |
7 |
646 |
|
| Salt Creek near Greenview |
1,804 |
83 |
146 |
459 |
225 |
122 |
987 |
|
| Sangamon River at Monticello |
550 |
116 |
1 |
118 |
26 |
8 |
337 |
|
| So. Fork Sangamon near Rochester |
867 |
76 |
6 |
176 |
23 |
3 |
456 |
|
| Illinois River at Valley City |
26,743 |
86 |
5,142 |
12,072 |
8,224 |
6,291 |
24,920 |
|
| Macoupin Creek near Kane |
868 |
97 |
25 |
204 |
46 |
8 |
498 |
|
| Vermilion River near Danville |
1,290 |
104 |
57 |
295 |
113 |
47 |
873 |
|
| Kaskaskia River at Vandalia |
1,940 |
55 |
43 |
552 |
320 |
50 |
1,811 |
|
| Shoal Creek near Breese |
735 |
83 |
38 |
178 |
59 |
12 |
434 |
|
| Embarras River at Ste. Marie |
1,516 |
113 |
45 |
349 |
115 |
37 |
1,055 |
|
| Skillet Fork at Wayne City |
464 |
108 |
2 |
85 |
19 |
1 |
229 |
|
| Little Wabash below Clay City |
1,131 |
111 |
18 |
232 |
63 |
8 |
826 |
|
| Big Muddy at Plumfield |
794 |
54 |
76 |
189 |
108 |
49 |
418 |
|
| Cache River at Forman |
244 |
101 |
9 |
55 |
13 |
2 |
183 |
|
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Choose another month Station Numbers are linked to the U.S. Geological Survey, providing more information about each station. Notes: Much below normal flow = 90-100% chance of exceedence. Below normal flow = 70-90% chance of exceedence. Normal flow = 30-70% chance of exceedence. Above normal flow = 10-30% chance of exceedence. Much above normal flow = 0-10% chance of exceedence. * As reported in U.S. Geological Survey (USGS) Water Resources Data, Illinois, Water Year 2023. For best results when printing this page, change your layout to "Landscape". Streamflow Data |