Big Sioux River near Brookings, SD
River level and flood forecast · Moody County
Normal2.4 ftas of Mon 3:45 PM
The river is 6.6 ft below flood stage (9 ft).
Flow: 115 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Sun, Dec 31, 6 PM. Forecasts change as rain falls and as upstream water arrives.
Flood stages
| Major flood stage | 15 ft |
| Moderate flood stage | 10.5 ft |
| Flood stage | 9 ft |
| Action stage | 8 ft |
| Record crest (April 9, 1969) | 14.77 ft |
What floods at each level
From the National Weather Service, highest first.
- 16 ftThe bridges on 473rd Avenue and 475th Avenue are overtopped.
- 14 ftThe water reaches the bottom of the bridges on 473rd Avenue and 475th Avenue.
- 13 ft223rd St west of the bridge begins to flood. The bridge 1 mile south of Medary on 471st Avenue is overtopped.
- 12 ft475th Avenue and 222nd Street begin to flood.
- 11.5 ft473rd Avenue at 221st Street begins to flood.
- 11 ftSome farm outbuildings begin to flood.
- 10.5 ft473rd Avenue north of the gauge begins to flood.
- 10 ftFlooding begins to affect agricultural lands along the right bank of the river.
- 9 ftSignificant amounts of pasture and farm lands begin flooding on the left bank of the river. The road south of the Brookings water treatment plant is flooded, as is 217th Street between 468th and 469th Avenues.
- 8 ftThere is some minor overflow of the lowest banks along this stretch of the river.
Highest crests on record
- 14.77 ft — April 9, 1969
- 14.34 ft — September 13, 2019
- 13.7 ft — June 22, 1984
- 13.66 ft — September 25, 2010
- 13.5 ft — July 4, 1993
Recent crests: 10.41 ft (July 3, 2025) · 11.06 ft (June 27, 2024) · 11.16 ft (April 14, 2023) · 7.09 ft (May 14, 2022) · 6.37 ft (April 11, 2021)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (BRKS2); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.