Rock River at Rock Rapids, IA
River level and flood forecast · Lyon County
Normal7.2 ftas of Mon 3:15 PM
The river is 5.8 ft below flood stage (13 ft).
Flow: 90 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 | 19 ft |
| Moderate flood stage | 16 ft |
| Flood stage | 13 ft |
| Action stage | 11 ft |
| Record crest (June 22, 2024) | 28.65 ft |
What floods at each level
From the National Weather Service, highest first.
- 28 ftWater reaches as far as Greene St on the west side of the river and the bridge on Hwy 9 in Rock Rapids is in danger of being overtopped.
- 27 ftSignificant flooding will be ongoing in Rock Rapids and water reaches as far Pearl St on the east side of the river and Tama St on the west side. Hwy 75 south of Rock Rapids may also become impassable.
- 26 ftWater reaches the bottom of the bridge on Hwy 9.
- 22 ftThe race track in Rock Rapids begins to flood as does N Boone St if water backs up Moon Creek
- 19 ftThe highest banks on the right side of the river will be overtopped with water beginning to encroach into the edges of Rock Rapids structures nearest the river.
- 16 ftThe higher banks on the left side become overtopped and more significant agriculture flooding begins.
- 15 ftMuch of the campground at Island Park in Rock Rapids is flooded.
- 13 ftThe lower banks become overtopped, including the lower lying areas of the Island Park Campground
Highest crests on record
- 28.65 ft — June 22, 2024
- 26.98 ft — June 17, 2014
- 22.25 ft — September 25, 2010
- 21.54 ft — September 14, 2019
- 20.8 ft — June 22, 2018
Recent crests: 10.61 ft (July 1, 2025) · 28.65 ft (June 22, 2024) · 13.4 ft (April 13, 2023) · 12.11 ft (July 6, 2022) · 9.26 ft (September 4, 2021)
Up and down the river, and nearby
- DownstreamRock River at Rock Valley, IA
- Burr Oak Creek above Perkins, IA
- Split Rock Creek at Corson, SD
- Little Floyd River near Sanborn, IA
- Big Sioux River at Sioux Falls N. Cliff Avenue, SD
- Big Sioux River at Sioux Falls Western Avenue, SD
- Big Sioux River above Hawarden, SD
- Silver Creek at Sioux Falls, SD
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (RAPI4); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.