Big Sioux River at Sioux City
Future / Actual / Minor
OWP 2.0 WWA Modal Title
01/11/2021, 10:04 PM UTC through 01/11/2021, 10:04 PM UTC
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Observed (OBS) 06/26/2025 8:30 PM CDTRecord: 44.9 ftCATEGORY STAGE 
Major Flooding 41 ft Moderate Flooding 38 ft Minor Flooding 32 ft Action 29 ft Reliability of the Forecast:
NOTE: Forecasts are issued as needed during times of high water, but are not routinely available.
River forecasts for this location take into account past and future precipitation. The stages/flows that will occur may be different if future rainfall is different than forecast.
National Water Model Hydrograph
Official NWS streamflow forecasts are produced by NWS hydrologic forecasters for river gauge locations using hydrologic models which are calibrated to that location. This process considers additional guidance and information, including local expertise and experience, to produce the best forecast possible. The NWM output provides supplemental guidance to NWS forecasters and should not be considered an official NWS river forecast.
Flood Impacts
- 48 - The levees on the South Dakota side are overtopped.
- 45.5 - More significant levee overtopping occurs in the Iowa Riverside Community.
- 43 - The lower levees in the Iowa Riverside community are in danger of being overtopped if not sandbagged.
- 38 - Most of the storm drains are submerged.
- 37 - Several structures south of River Dr on the SD will flood if a levee failure occurs.
Gauge Location
Recent Crests
| 1. | 44.90 ft | on 06-23-2024 |
| 2. | 18.57 ft | on 04-15-2023 |
| 3. | 14.94 ft | on 06-02-2022 |
| 4. | 12.37 ft | on 09-01-2021 |
| 5. | 21.89 ft | on 04-02-2020 |
Recent Crests
| 1. | 44.90 ft | on 06-23-2024 |
| 2. | 18.57 ft | on 04-15-2023 |
| 3. | 14.94 ft | on 06-02-2022 |
| 4. | 12.37 ft | on 09-01-2021 |
| 5. | 21.89 ft | on 04-02-2020 |
| 6. | 37.46 ft | on 03-17-2019 |
| 7. | 31.57 ft | on 06-25-2018 |
| 8. | 17.73 ft | on 05-26-2017 |
| 9. | 19.04 ft | on 05-04-2016 |
| 10. | 15.09 ft | on 07-10-2015 |
| 11. | 37.70 ft | on 06-20-2014 |
Historic Crests
| 1. | 44.90 ft | on 06-23-2024 |
| 2. | 37.70 ft | on 06-20-2014 |
| 3. | 37.46 ft | on 03-17-2019 |
| 4. | 31.57 ft | on 06-25-2018 |
| 5. | 21.89 ft | on 04-02-2020 |
Historic Crests
| 1. | 44.90 ft | on 06-23-2024 |
| 2. | 37.70 ft | on 06-20-2014 |
| 3. | 37.46 ft | on 03-17-2019 |
| 4. | 31.57 ft | on 06-25-2018 |
| 5. | 21.89 ft | on 04-02-2020 |
| 6. | 19.04 ft | on 05-04-2016 |
| 7. | 18.57 ft | on 04-15-2023 |
| 8. | 17.73 ft | on 05-26-2017 |
| 9. | 15.09 ft | on 07-10-2015 |
| 10. | 14.94 ft | on 06-02-2022 |
| 11. | 12.37 ft | on 09-01-2021 |
Vertical Datum Table
| type | NAVD88 |
|---|---|
| major Flooding | 1101.00 ft |
| moderate Flooding | 1098.00 ft |
| minor Flooding | 1092.00 ft |
| action | 1089.00 ft |
| Latest Value | 1070.86 ft |
| Gauge Zero | 1060.00 ft |
Collaborative Agencies
The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here.
Resources
Hydrologic Resource Links
- River Forecast Centers
- NWS Sioux Falls Flooding Resource Page
- NOHRSC Snow Information
- USACE Missouri River Water Management
- USGS National Water Dashboard
- FEMA Flood Insurance Information
- South Dakota Flood Information System
- Iowa Flood Information System
- Missouri River Flood Information System
- Minnesota DNR
- Nebraska Real-Time Flood Forecasting
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