Provisional Monthly Streamflow Network - Tabular Data: August 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 |
6,320 |
3,365 |
2,941 |
1,280 |
5,670 |
|
| Rock River near Joslin |
9,549 |
85 |
8,515 |
5,100 |
4,361 |
2,057 |
9,318 |
|
| Pecatonica River at Freeport |
1,326 |
110 |
1,248 |
811 |
673 |
334 |
1,516 |
|
| Green River near Geneseo |
1,003 |
89 |
305 |
396 |
260 |
99 |
1,073 |
|
| Edwards River near New Boston |
445 |
90 |
208 |
156 |
85 |
22 |
384 |
|
| Kankakee River at Momence |
2,294 |
111 |
1,585 |
1,151 |
953 |
617 |
1,940 |
|
| Iroquois River near Chebanse |
2,091 |
102 |
436 |
499 |
238 |
64 |
1,325 |
|
| Fox River at Dayton |
2,642 |
110 |
2,012 |
1,064 |
739 |
317 |
2,080 |
|
| Vermilion River at Pontiac |
579 |
82 |
100 |
127 |
34 |
8 |
348 |
|
| Spoon River at Seville |
1,636 |
111 |
503 |
495 |
304 |
80 |
965 |
|
| LaMoine River at Ripley |
1,293 |
104 |
250 |
338 |
194 |
35 |
971 |
|
| Bear Creek near Marcelline |
349 |
81 |
27 |
95 |
51 |
1 |
279 |
|
| Mackinaw River near Congerville |
767 |
80 |
49 |
161 |
62 |
13 |
397 |
|
| Salt Creek near Greenview |
1,804 |
83 |
408 |
614 |
364 |
163 |
1,226 |
|
| Sangamon River at Monticello |
550 |
116 |
13 |
143 |
49 |
12 |
463 |
|
| So. Fork Sangamon near Rochester |
867 |
76 |
44 |
211 |
70 |
6 |
512 |
|
| Illinois River at Valley City |
26,743 |
86 |
13,522 |
13,665 |
11,800 |
7,619 |
22,380 |
|
| Macoupin Creek near Kane |
868 |
97 |
111 |
204 |
73 |
14 |
535 |
|
| Vermilion River near Danville |
1,290 |
104 |
89 |
389 |
175 |
51 |
1,001 |
|
| Kaskaskia River at Vandalia |
1,940 |
55 |
270 |
949 |
841 |
97 |
2,122 |
|
| Shoal Creek near Breese |
735 |
83 |
53 |
216 |
78 |
17 |
664 |
|
| Embarras River at Ste. Marie |
1,516 |
113 |
256 |
416 |
193 |
61 |
924 |
|
| Skillet Fork at Wayne City |
464 |
108 |
25 |
151 |
25 |
1 |
483 |
|
| Little Wabash below Clay City |
1,131 |
111 |
169 |
397 |
118 |
18 |
1,176 |
|
| Big Muddy at Plumfield |
794 |
54 |
214 |
307 |
229 |
56 |
660 |
|
| Cache River at Forman |
244 |
101 |
30 |
71 |
23 |
4 |
196 |
|
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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 |