Big Sioux River near Castlewood
Observed Mon, Sep 28, 7:45 AM CDT
- Flood stage
- 9.00 ft
- Record crest
- 13.19 ft1997
Flood stages and impacts
| Category | Stage |
|---|---|
| Major flood | 16.00 ft |
| Moderate flood | 11.00 ft |
| Minor flood | 9.00 ft |
| Action | 8.00 ft |
- 18.00 ft479th Avenue begins to flood south of Castlewood.
- 17.00 ftHighway 22 begins to flood, as does 181st Street, and water reaches the bottom of the bridge on 459th Avenue south of Castlewood.
- 16.00 ftThe river will be about 1 mile wide and many farm buildings around Castlewood will be flooded.
- 15.00 ftThe water reaches the bottom of the bridges on Highway 22 and 181st Street.
- 13.00 ftMajor agricultural flooding begins south of Castlewood.
- 11.00 ftSignificant amounts of pasture and other agricultural lands will be flooded.
- 10.00 ft184th Street begins to flood.
- 9.00 ftWater overtops the culvert on 184th Street and significant agricultural flooding begins north of Castlewood.
- 8.00 ftMinor flooding of low-lying agricultural lands along the river will begin.
Flood outlook
Chance of flooding, September to November
| Category | Chance |
|---|---|
| Minor flooding | 14% |
| 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
48 crests on NOAA’s list since 1977.
| # | Date | Stage |
|---|---|---|
| 1 | April 7, 1997 | 13.19 ft |
| 2 | March 28, 2019 | 12.39 ft |
| 3 | March 23, 2011 | 12.29 ft |
| 4 | April 8, 2001 | 12.27 ft |
| 5 | March 15, 2010 | 11.98 ft |
| 6 | March 30, 1986 | 11.73 ft |
| 7 | March 14, 1996 | 11.65 ft |
| 8 | April 13, 2023 | 11.64 ft |
| 9 | July 29, 2025 | 11.44 ft |
| 10 | March 28, 1993 | 11.39 ft |
| 11 | March 13, 1995 | 11.37 ft |
| 12 | March 24, 2009 | 11.28 ft |
| 13 | April 13, 1979 | 11.23 ft |
| 14 | March 16, 1994 | 11.21 ft |
| 15 | March 19, 1985 | 11.14 ft |
| 16 | March 31, 1978 | 11.10 ft |
| 17 | April 23, 2018 | 10.93 ft |
| 18 | June 22, 1991 | 10.93 ft |
| 19 | June 1, 2022 | 10.70 ft |
| 20 | June 16, 1984 | 10.68 ft |
| 21 | March 20, 2007 | 10.65 ft |
| 22 | June 16, 1977 | 10.33 ft |
| 23 | April 1, 1998 | 9.98 ft |
| 24 | March 25, 1989 | 9.81 ft |
| 25 | March 16, 2003 | 9.63 ft |
Most recent crests
- July 29, 2025: 11.44 ft
- April 13, 2023: 11.64 ft
- June 1, 2022: 10.70 ft
- April 10, 2021: 8.37 ft
- April 3, 2020: 9.53 ft
- March 28, 2019: 12.39 ft
- April 23, 2018: 10.93 ft
- February 20, 2017: 8.60 ft
- August 12, 2016: 6.93 ft
- March 13, 2015: 8.75 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. 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.