Big Sioux River above Hawarden, SD
River level and flood forecast · Sioux County
Normal12.1 ftas of Mon 3:30 PM
The river is 8.4 ft below flood stage (20.5 ft).
Flow: 714 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 | 30 ft |
| Moderate flood stage | 24 ft |
| Flood stage | 20.5 ft |
| Action stage | 18.5 ft |
| Record crest (June 22, 2024) | 39.92 ft |
What floods at each level
From the National Weather Service, highest first.
- 39 ftSignificant flooding continues in Hawarden with roughly the western half of the town flooded.
- 35 ftWater overtops 10th St and floods the lower portions of Hawarden south of 10th St and west of Highway 10.
- 34 ftSeveral structures near the river off of 10th St in Haward are flooded or surrounded by water.
- 32 ftWater backs up into the park in Hawarden, and some basements and sewers could begin to have problems.
- 30.5 ftIowa Highway 10 begins to flood.
- 30 ftSouth Dakota Highway 46 begins to flood north of Hawarden.
- 29.5 ftCounty Road 13 begins to flood west of Hawarden. The lowest campsites at the Big Sioux Recreation Area are flooded.
- 27.5 ftRiver Road between 304th St and County Road 13 begins to flood.
- 25.5 ftWater may begin to backup the drainage ditches into the lakes at the Big Sioux Recreation Area in Hawarden.
- 24 ftSome farm houses on the South Dakota side of the river are isolated by high water.
- 20.5 ftAgricultural flooding begins on the South Dakota side of the river.
Highest crests on record
- 39.92 ft — June 22, 2024
- 35.2 ft — March 15, 2019
- 34 ft — June 22, 2018
- 32.42 ft — September 15, 2019
- 23.02 ft — March 30, 2020
Recent crests: 16.39 ft (July 6, 2025) · 39.92 ft (June 22, 2024) · 22.89 ft (April 13, 2023) · 18.88 ft (June 1, 2022) · 17.3 ft (August 30, 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 (HWDI4); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.