Big Sioux River at Sioux City
Observed Thu, Sep 24, 3:30 AM CDT
- Flood stage
- 32.00 ft
- Record crest
- 44.90 ft2024
Flood stages and impacts
| Category | Stage |
|---|---|
| Major flood | 41.00 ft |
| Moderate flood | 38.00 ft |
| Minor flood | 32.00 ft |
| Action | 29.00 ft |
- 48.00 ftThe levees on the South Dakota side are overtopped.
- 45.50 ftMore significant levee overtopping occurs in the Iowa Riverside Community with numerous homes and buildings flooded.
- 43.00 ftThe lower levees in the Iowa Riverside community are in danger of being overtopped if not sandbagged. This may result in flooding of several homes on either side of Dacotan Ave.
- 38.00 ftMost of the storm drains are submerged.
- 37.00 ftSeveral structures south of River Dr on the SD will flood if a levee failure occurs.
- 35.00 ftSome lower portions south of River Dr on the SD may be at risk of flooding with a levee failure.
- 32.00 ftAgricultural land north of the leveed area begins to flood.
Flood outlook
Chance of flooding, September to November
| Category | Chance |
|---|---|
| Minor flooding | Under 5% |
| Moderate flooding | Under 5% |
| Major flooding | Under 5% |
The three-month chances are the River Forecast Centers’ long-range flood outlook, issued September 23, 2026.
Crest history
12 crests on NOAA’s list since 2014.
| # | Date | Stage |
|---|---|---|
| 1 | June 23, 2024 | 44.90 ft |
| 2 | June 20, 2014 | 37.70 ft |
| 3 | March 17, 2019 | 37.46 ft |
| 4 | June 25, 2018 | 31.57 ft |
| 5 | April 2, 2020 | 21.89 ft |
| 6 | May 4, 2016 | 19.04 ft |
| 7 | April 15, 2023 | 18.57 ft |
| 8 | May 26, 2017 | 17.73 ft |
| 9 | July 10, 2015 | 15.09 ft |
| 10 | June 2, 2022 | 14.94 ft |
| 11 | July 8, 2025 | 13.27 ft |
| 12 | September 1, 2021 | 12.37 ft |
Most recent crests
- July 8, 2025: 13.27 ft
- June 23, 2024: 44.90 ft
- April 15, 2023: 18.57 ft
- June 2, 2022: 14.94 ft
- September 1, 2021: 12.37 ft
- April 2, 2020: 21.89 ft
- March 17, 2019: 37.46 ft
- June 25, 2018: 31.57 ft
- May 26, 2017: 17.73 ft
- May 4, 2016: 19.04 ft
Nearby
Upstream, downstream and the gauges around this one.
What this means
Forecasts by the Missouri Basin River Forecast Center. Forecasts are issued as needed during times of high water, but are not routinely available. River forecasts for this location take into account past precipitation and the precipitation amounts expected approximately 48 hours into the future from the forecast issuance time. River forecasts for this location take into account past precipitation and the precipitation amounts expected approximately 24 hours into the future from the forecast issuance time. Gauge reading may be affected by ice.
Sources
Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service. Streamflow and the daily record from the U.S. Geological Survey.