Big Sioux River near Watertown, SD
River level and flood forecast · Codington County
Normal3.8 ftas of Mon 2 PM
The river is 6.2 ft below flood stage (10 ft).
Flow: 4 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 | 12 ft |
| Moderate flood stage | 11 ft |
| Flood stage | 10 ft |
| Action stage | 9 ft |
| Record crest (April 7, 2001) | 12.33 ft |
What floods at each level
From the National Weather Service, highest first.
- 20 ftThe bridge at the gaging location is overtopped
- 19 ftThe bridge 1 mile south of the gage is overtopped
- 16 ftThe water reaches the bottom of the bridge at the gage and the bridge 1 mile south of the gage
- 13 ftFlooding begins to affect the city of watertown and the sidewalk on the highway 81 bridge is overtopped
- 12.5 ftCounty roads begin to flood
- 11.5 ftSignificant amounts of pasture and crop land are flooded
- 9 ftThe lowest banks are overtopped and minimal areas of pasture land will be flooded
Highest crests on record
- 12.33 ft — April 7, 2001
- 12.09 ft — April 5, 1997
- 11.85 ft — April 13, 2023
- 11.21 ft — March 28, 2019
- 11.07 ft — March 30, 1978
Recent crests: 10.61 ft (August 6, 2025) · 11.85 ft (April 13, 2023) · 10.11 ft (May 31, 2022) · 7.12 ft (April 10, 2021) · 9.08 ft (October 23, 2019)
Up and down the river, and nearby
- UpstreamBig Sioux River near Florence, SD
- DownstreamBig Sioux River at Lake Kampeska, SD
- Mud Creek near Rauville, SD
- Big Sioux River at Watertown Sioux Conifer Road, SD
- South Branch Tributary Mud Creek near Rauville, SD
- Lake Kampeska at Watertown Water Plant, SD
- Big Sioux River at Watertown Broadway Avenue, SD
- Willow Creek near Watertown, SD
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (WTRS2); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.