Illinois River at Seneca water level

Name: Illinois River at Seneca water level (U.S. Geological Survey)
Creator: U.S. Geological Survey
License: https://www.usgs.gov/information-policies-and-instructions/copyrights-and-credits

River gauge, Illinois River, Illinois, United States

Directions

Low for mid-October

Water level

20.40ft Down 0.05 ft over the last 24 hours

Measured Oct 17, 2026, 03:45 PM CDT (1 hour ago)

Water temperature: 64 °F

History

7 days 30 days 1 year Years compared

20252026

Water level Normal range (10–90 %)

What this means

The Illinois River at Seneca is running below normal at 20.40 ft.

The median for mid-October is 20.72 ft, based on 13 years of readings, so the river stage is 0.32 ft below typical. On the same day last year the reading was 20.36 ft, a difference of +0.04 ft.

It has dropped 0.05 ft over the past 24 hours. Without real rain upstream, that is unlikely to change quickly. In the last month it has stayed between 20.36 ft and 22.22 ft.

Fall is often low-water season on rivers, and it usually takes a few days of steady rain to change that. The water temperature at the gauge is 64 °F.

Compared with 13 years of daily readings for this time of year. How to read levels

Key numbers

Median for this date: 20.72 ft0.32 ft below the median for this date
Normal for this date: 20.25 ft – 22.89 ft8 years in 10 fall in this range (13 years of records)
Same day last year: 20.36 ft+0.04 ft
Lowest and highest in 30 days: 20.36 ft – 22.22 ft
Lowest and highest in 12 months: 19.70 ft – 25.16 ft
Highest on record: 32.25 ftMay 19, 2020

Floating and fishing near Illinois River at Seneca

Low water exposes gravel bars that make good wading access, but some boat ramps may be left high and dry.

What happens at each level

36.00 ft: Backwater causes Rat Run to threatened Main Street in Seneca.
35.50 ft: A few residences threatened near River Road and IL-170 in Seneca.
35.00 ft: River Road is threatened near IL-170 in Seneca.
33.50 ft: Industrial structures are threatened along the river west of Seneca.
33.00 ft: Backwater causes Rat Run to threaten a few structures near Main Street in Seneca.
32.00 ft: IL-36 (Dupont Road) is threatened along the river near Seneca.
31.50 ft: Old Stage Road is threatened just east of Seneca.
31.00 ft: Backwater causes Rat Run to overtop its banks near Main Street in Seneca.
28.00 ft: Old Stage Road is threatened near the Illinois and Michigan Canal between Seneca and Morris. Agricultural land is inundated north of the river near Seneca.
27.00 ft: Roadways at numerous marinas threatened along the river near Seneca.
25.00 ft: Water overtops low-lying banks in Seneca.
20.40 ft: Right now

Impact statements from the U.S. National Weather Service.

Highest crests on record

Rank	Level	Date
1	32.25 ft	May 19, 2020
2	32.16 ft	May 2, 2019
3	30.78 ft	February 21, 2018
4	27.94 ft	September 29, 2019
5	27.36 ft	May 2, 2017

Weather at the gauge

Rain in the last 3 days: 0.09 in. Rain that falls upstream can take hours or days to show up at a river gauge.

17 Sat 55° 37° – Wind 9 mph

18 Sun 63° 39° – Wind 12 mph

19 Mon 67° 41° – Wind 6 mph

20 Tue 68° 49° – Wind 6 mph

21 Wed 70° 50° – Wind 7 mph

22 Thu 64° 56° 0.01 in Wind 6 mph

23 Fri 73° 52° – Wind 9 mph

Forecast: Open-Meteo

Sunrise 07:09 AM Sunset 06:12 PM Daylight 11 hr, 3 min First quarter 44%

Map

Other gauges on the Illinois River

Gauge	Level	Compared with normal	24 hours	Distance
Illinois River at MorrisRiver gauge, Illinois River	4.85 ft	Low	−0.20 ft	10 mi
Illinois River at MarseillesRiver gauge, Illinois River	11.40 ft	Normal	±0	5.7 mi
Illinois River at HenryRiver gauge, Illinois River	15.28 ft	Normal	±0	41 mi
Illinois River at Kingston MinesRiver gauge, Illinois River	6.21 ft	Normal	+0.37 ft	80 mi
Illinois River at Copperas CreekRiver gauge, Illinois River	5.74 ft	Normal	+0.49 ft	88 mi
Illinois River at MeredosiaRiver gauge, Illinois River	5.00 ft	Normal	−0.08 ft	144 mi
Illinois River at Valley CityRiver gauge, Illinois River	4.07 ft	Normal	−0.03 ft	153 mi

Nearby gauges

Gauge	Level	Compared with normal	24 hours	Distance
Fox River at DaytonRiver gauge, Fox River	7.52 ft	Normal	−0.31 ft	11 mi
Mazon River near Coal CityRiver gauge, Mazon River	1.53 ft	Normal	±0	13 mi
Aux Sable Creek near MorrisRiver gauge, Aux Sable Creek	4.01 ft	Normal	−0.45 ft	16 mi
Vermilion River near LeonoreRiver gauge, Vermilion River	3.68 ft	Normal	−0.08 ft	18 mi
Kankakee River at Inflow of Power Plant near LorenzoRiver gauge, Kankakee River	504.57 ft	Low	−0.05 ft	19 mi
Kankakee River near WilmingtonRiver gauge, Kankakee River	1.53 ft	Normal	−0.06 ft	22 mi
Fox River Tailwater at YorkvilleRiver gauge, Fox River Tailwater	7.62 ft	Normal	−0.13 ft	25 mi
Fox River Bypass at YorkvilleRiver gauge, Fox River Bypass	9.33 ft	Normal	−0.05 ft	25 mi

Questions and answers

Is the Illinois River at Seneca higher than last year?

Yes, it is 0.04 ft higher than on the same day last year, when the reading was 20.36 ft.

What is a normal level for the Illinois River at Seneca in mid-October?

The median for mid-October is 20.72 ft. In 8 years out of 10 the reading falls between 20.25 ft and 22.89 ft, based on 13 years of records.

Is gage height the same as water depth?

No. Gage height is measured from a fixed reference point chosen by the agency, so a reading of 10 ft does not mean the river is 10 ft deep.

What is the water level of Illinois River at Seneca today?

On Oct 17, 2026, 03:45 PM CDT, the water level was 20.40 ft. Down 0.05 ft over the last 24 hours.

Is Illinois River at Seneca rising or falling?

Down 0.05 ft over the last 24 hours. Down 0.17 ft over the last 7 days.

Is the level of Illinois River at Seneca normal?

Low for mid-October. Compared with 13 years of daily readings for this time of year.

What is the highest water level ever recorded at Illinois River at Seneca?

The highest level on record is 32.25 ft on May 19, 2020.

For specialists

Station codes, datum, parameters, data quality and downloads

Operator: U.S. Geological Survey
Station code: usgs:05543010 (Agency page)
Coordinates: 41.29989, -88.61419 (WGS84)
Vertical datum: NAVD88
Update interval: every 15 minutes
Licence: Public domain. Data: U.S. Geological Survey (USGS), provisional data subject to revision

Published series

Parameter	Last value	Time (UTC)	Quality
Water level	20.40 ft	2026-10-17 20:45	Provisional
Water temperature	64 °F	2026-10-17 20:45	Provisional

Download

Embed this gauge

Add a live card for this gauge to your website. It updates on its own and links back here.

<iframe src="https://nivelmap.com/embed/13183?lang=en" width="360" height="230" style="border:0;max-width:100%" loading="lazy" title="Illinois River at Seneca water level"></iframe>

How to cite

U.S. Geological Survey: Illinois River at Seneca (usgs:05543010). Accessed October 17, 2026 via Nivelmap, https://nivelmap.com/en/united-states/illinois/illinois-river-at-seneca

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.

Readings are provisional, can be delayed or wrong and are not a flood warning. Read the disclaimer