Mississippi River Pool Lock and Dam 26 at Alton water level

Name: Mississippi River Pool Lock and Dam 26 at Alton 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, Mississippi River Pool Lock and Dam 26, Illinois, United States

Directions

Below flood stage

Water level

18.27ft Up 0.25 ft over the last 24 hours

Measured Oct 20, 2026, 04:30 PM CDT (36 min ago)

Water temperature: 64 °F

History

7 days

Water level Minor flood stage

What this means

The gauge at Mississippi River Pool Lock and Dam 26 at Alton reads 18.27 ft, a normal level.

It is 2.73 ft below the flood stage of 21.00 ft.

The water is rising: up 0.25 ft over the past 24 hours. There is still 2.73 ft of room before flood stage. Over the past 30 days it has moved between 17.80 ft and 19.64 ft.

Fall is often low-water season on rivers, until steadier rain returns. The water temperature at the gauge is 64 °F.

Judged against the official flood stage for this gauge. How to read levels

Key numbers

Highest on record: 39.55 ftAugust 1, 1993

What the stage means on the water

A normal level is usually prime time for floating and wade fishing, as long as the weather holds upstream.

The National Weather Service puts flood stage for this gauge at 21.00 ft, still 2.73 ft away.

What happens at each level

39.00 ft: Near this height, floodwaters will reach the floor of the Lincoln Shields gazebo in West Alton, Missouri.
38.70 ft: Near this height U.S. Highway 67 will be completely closed.
36.70 ft: The railroad between Wood River and Alton begins flooding near this height.
32.00 ft: At this height, the waterpark playground will become inundated.
31.20 ft: Near this height, the southbound lanes of U.S. Highway 67 will begin flooding, forcing the detour of southbound traffic onto the northbound lanes.
30.90 ft: Near this height, water will begin flowing over Riverlands Way between Highway 67 and Mel Price Locks and Dam. This road is a part of the Consolidated North County levee, so this is the point when water begins gradually flowing onto the protected farmland and farm homes behind the levee.
30.80 ft: The intersection of West Broadway (Illinois 100) and U.S. Highway 67 will begin flooding near this height.
29.70 ft: Floodwater begins damaging property in Elsah, Illinois and in Portage des Sioux, Missouri near this height.
29.20 ft: Near this height, floodwater should begin to impact the base of the Ardent Mills grain bins.
28.20 ft: At this height, water will cover the sidewalk near the waterpark playground.
28.00 ft: Near this height, the flood wall around the Argosy Casino will overtop, flooding the casino parking lot.
27.20 ft: At this height, Bloch Marine Service at Harbor Point Yacht Club begins flooding.
18.27 ft: Right now

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

Highest crests on record

Chance of at least minor flooding in October to December: < 5 %.

Rank	Level	Date
1	39.55 ft	August 1, 1993
2	35.30 ft	June 9, 2019
3	31.94 ft	January 1, 2016
4	31.60 ft	May 7, 2019
5	31.43 ft	May 22, 1995
6	31.27 ft	June 4, 2013
7	31.02 ft	May 6, 2017
8	29.78 ft	June 29, 2008
9	29.11 ft	June 30, 2015
10	28.77 ft	April 3, 2019

Weather at the gauge

No rain in the last 3 days.

20 Tue 73° 48° – Wind 5 mph

21 Wed 76° 48° – Wind 5 mph

22 Thu 77° 53° – Wind 6 mph

23 Fri 77° 55° – Wind 8 mph

24 Sat 79° 56° – Wind 9 mph

25 Sun 78° 59° – Wind 10 mph

26 Mon 76° 48° – Wind 14 mph

Forecast: Open-Meteo

Sunrise 07:16 AM Sunset 06:17 PM Daylight 11 hr, 1 min Waxing gibbous 72%

Map

Nearby gauges

Gauge	Level	Compared with normal	24 hours	Distance
Coldwater Creek near Black JackRiver gauge, Coldwater Creek	4.5 cfs	Normal	−0.4 cfs	6.0 mi
Mill Creek near FlorissantRiver gauge, Mill Creek	0.3 cfs	Normal	−1.2 cfs	6.1 mi
Spanish Lake Tributary near Black JackRiver gauge, Spanish Lake Tributary	0.1 cfs	Normal	±0	6 mi
Watkins Creek near Bellefontaine NeighborsRiver gauge, Watkins Creek	0.0 cfs	Normal	±0	8 mi
Indian Creek at WandaRiver gauge, Indian Creek	0.28 ft	Very low	−0.05 ft	9 mi
Maline Creek at Bellefontaine NeighborsRiver gauge, Maline Creek	2.8 cfs	Normal	−0.3 cfs	11 mi
Cahokia Creek at EdwardsvilleRiver gauge, Cahokia Creek	3.21 ft	Low	−0.04 ft	12 mi
Mississippi River at GraftonRiver gauge, Mississippi River	15.25 ft	Below flood stage	+0.14 ft	14 mi

Questions and answers

What is flood stage for the Mississippi River Pool Lock and Dam 26 at Alton?

The official flood stage is 21.00 ft. The level is currently 2.73 ft below it.

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 Mississippi River Pool Lock and Dam 26 at Alton today?

On Oct 20, 2026, 04:30 PM CDT, the water level was 18.27 ft. Up 0.25 ft over the last 24 hours.

Is Mississippi River Pool Lock and Dam 26 at Alton rising or falling?

Up 0.25 ft over the last 24 hours.

Is the level of Mississippi River Pool Lock and Dam 26 at Alton normal?

Below flood stage. Judged against the official flood stage for this gauge.

What is the highest water level ever recorded at Mississippi River Pool Lock and Dam 26 at Alton?

The highest level on record is 39.55 ft on August 1, 1993.

How often is this data updated?

The U.S. Geological Survey publishes a new reading every 15 minutes. This page refreshes within minutes of each update.

For specialists

Station codes, datum, parameters, data quality and downloads

Operator: U.S. Geological Survey
Station code: usgs:05587498 (Agency page)
Coordinates: 38.88731, -90.18400 (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	18.27 ft	2026-10-20 21:30	Provisional
Water temperature	64 °F	2026-10-20 21:00	Provisional

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How to cite

U.S. Geological Survey: Mississippi River Pool Lock and Dam 26 at Alton (usgs:05587498). Accessed October 20, 2026 via Nivelmap, https://nivelmap.com/en/united-states/illinois/mississippi-river-pool-lock-and-dam-26-at-alton

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