Big Sioux River near Castlewood
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) 06/09/2025 7:45 AM CDTRecord: 13.2 ftCATEGORY STAGE 
Major Flooding 16 ft Moderate Flooding 11 ft Minor Flooding 9 ft Action 8 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 precipitation and the precipitation amounts expected approximately 48 hours into the future from the forecast issuance time.
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
- 18 - 479th Avenue begins to flood south of Castlewood.
- 17 - Highway 22 begins to flood, as does 181st Street, and water reaches the bottom of the bridge on 459th Avenue south of Castlewood.
- 16 - The river will be about 1 mile wide and many farm buildings around Castlewood will be flooded.
Gauge Location
Recent Crests
| 1. | 11.64 ft | on 04-13-2023 |
| 2. | 10.70 ft | on 06-01-2022 |
| 3. | 8.37 ft | on 04-10-2021 |
| 4. | 9.53 ft | on 04-03-2020 |
| 5. | 12.39 ft | on 03-28-2019 |
Recent Crests
| 1. | 11.64 ft | on 04-13-2023 |
| 2. | 10.70 ft | on 06-01-2022 |
| 3. | 8.37 ft | on 04-10-2021 |
| 4. | 9.53 ft | on 04-03-2020 |
| 5. | 12.39 ft | on 03-28-2019 |
| 6. | 10.93 ft | on 04-23-2018 |
| 7. | 8.60 ft | on 02-20-2017 |
| 8. | 6.93 ft | on 08-12-2016 |
| 9. | 8.75 ft | on 03-13-2015 |
| 10. | 6.97 ft | on 06-22-2014 |
| 11. | 9.02 ft | on 06-24-2013 |
| 12. | 7.40 ft | on 03-13-2012 |
| 13. | 12.29 ft | on 03-23-2011 |
| 14. | 11.98 ft | on 03-15-2010 |
| 15. | 11.28 ft | on 03-24-2009 |
| 16. | 8.27 ft | on 06-13-2008 |
| 17. | 10.65 ft | on 03-20-2007 |
| 18. | 8.33 ft | on 03-11-2006 |
| 19. | 7.20 ft | on 06-11-2005 |
| 20. | 6.24 ft | on 07-03-2004 |
| 21. | 9.63 ft | on 03-16-2003 |
| 22. | 9.63 ft | on 08-21-2002 |
| 23. | 12.27 ft | on 04-08-2001 |
| 24. | 5.34 ft | on 06-26-2000 |
| 25. | 7.79 ft | on 06-10-1999 |
| 26. | 9.98 ft | on 04-01-1998 |
| 27. | 13.19 ft | on 04-07-1997 |
| 28. | 11.65 ft | on 03-14-1996 |
| 29. | 11.37 ft | on 03-13-1995 |
| 30. | 11.21 ft | on 03-16-1994 |
| 31. | 11.39 ft | on 03-28-1993 |
| 32. | 9.15 ft | on 06-19-1992 |
| 33. | 10.93 ft | on 06-22-1991 |
| 34. | 6.53 ft | on 06-17-1990 |
| 35. | 9.81 ft | on 03-25-1989 |
| 36. | 7.60 ft | on 03-02-1988 |
| 37. | 7.88 ft | on 03-25-1987 |
| 38. | 11.73 ft | on 03-30-1986 |
| 39. | 11.14 ft | on 03-19-1985 |
| 40. | 10.68 ft | on 06-16-1984 |
| 41. | 7.26 ft | on 04-01-1983 |
| 42. | 8.62 ft | on 03-31-1982 |
| 43. | 7.60 ft | on 07-22-1981 |
| 44. | 8.80 ft | on 06-05-1980 |
| 45. | 11.23 ft | on 04-13-1979 |
| 46. | 11.10 ft | on 03-31-1978 |
| 47. | 10.33 ft | on 06-16-1977 |
Historic Crests
| 1. | 13.19 ft | on 04-07-1997 |
| 2. | 12.39 ft | on 03-28-2019 |
| 3. | 12.29 ft | on 03-23-2011 |
| 4. | 12.27 ft | on 04-08-2001 |
| 5. | 11.98 ft | on 03-15-2010 |
Historic Crests
| 1. | 13.19 ft | on 04-07-1997 |
| 2. | 12.39 ft | on 03-28-2019 |
| 3. | 12.29 ft | on 03-23-2011 |
| 4. | 12.27 ft | on 04-08-2001 |
| 5. | 11.98 ft | on 03-15-2010 |
| 6. | 11.73 ft | on 03-30-1986 |
| 7. | 11.65 ft | on 03-14-1996 |
| 8. | 11.64 ft | on 04-13-2023 |
| 9. | 11.39 ft | on 03-28-1993 |
| 10. | 11.37 ft | on 03-13-1995 |
| 11. | 11.28 ft | on 03-24-2009 |
| 12. | 11.23 ft | on 04-13-1979 |
| 13. | 11.21 ft | on 03-16-1994 |
| 14. | 11.14 ft | on 03-19-1985 |
| 15. | 11.10 ft | on 03-31-1978 |
| 16. | 10.93 ft | on 06-22-1991 |
| 17. | 10.93 ft | on 04-23-2018 |
| 18. | 10.70 ft | on 06-01-2022 |
| 19. | 10.68 ft | on 06-16-1984 |
| 20. | 10.65 ft | on 03-20-2007 |
| 21. | 10.33 ft | on 06-16-1977 |
| 22. | 9.98 ft | on 04-01-1998 |
| 23. | 9.81 ft | on 03-25-1989 |
| 24. | 9.63 ft | on 08-21-2002 |
| 25. | 9.63 ft | on 03-16-2003 |
| 26. | 9.53 ft | on 04-03-2020 |
| 27. | 9.15 ft | on 06-19-1992 |
| 28. | 9.02 ft | on 06-24-2013 |
| 29. | 8.80 ft | on 06-05-1980 |
| 30. | 8.75 ft | on 03-13-2015 |
| 31. | 8.62 ft | on 03-31-1982 |
| 32. | 8.60 ft | on 02-20-2017 |
| 33. | 8.37 ft | on 04-10-2021 |
| 34. | 8.33 ft | on 03-11-2006 |
| 35. | 8.27 ft | on 06-13-2008 |
| 36. | 7.88 ft | on 03-25-1987 |
| 37. | 7.79 ft | on 06-10-1999 |
| 38. | 7.60 ft | on 03-02-1988 |
| 39. | 7.60 ft | on 07-22-1981 |
| 40. | 7.40 ft | on 03-13-2012 |
| 41. | 7.26 ft | on 04-01-1983 |
| 42. | 7.20 ft | on 06-11-2005 |
| 43. | 6.97 ft | on 06-22-2014 |
| 44. | 6.93 ft | on 08-12-2016 |
| 45. | 6.53 ft | on 06-17-1990 |
| 46. | 6.24 ft | on 07-03-2004 |
| 47. | 5.34 ft | on 06-26-2000 |
Vertical Datum Table
| type | NAVD88 |
|---|---|
| major Flooding | 1684.48 ft |
| moderate Flooding | 1679.48 ft |
| minor Flooding | 1677.48 ft |
| action | 1676.48 ft |
| Latest Value | 1673.63 ft |
| Gauge Zero | 1668.48 ft |
Unique Local Info
Effective on Friday, June 1 2012, the Minor Flood Stage has been changed to 9.0 feet, and the Moderate Flood Stage changed to 11.0 feet.
How low could the river
get?
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.