Big River at Byrnesville, MO
River level and flood forecast · Jefferson County
Normal1.6 ftas of Mon 3:45 PM
The river is 14.4 ft below flood stage (16 ft).
Flow: 104 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 | 28 ft |
| Moderate flood stage | 20 ft |
| Flood stage | 16 ft |
| Action stage | 13 ft |
| Record crest (August 21, 1915) | 30.2 ft |
What floods at each level
From the National Weather Service, highest first.
- 30.3 ftThe porch of the upstream left bank residence floods at this level.
- 29.6 ftThe main floor at the Byrnesville mill begins to flood.
- 29.4 ftThe floor of the gage shed begins to flood.
- 28 ftAt this height, several homes along Burgan Grove Road are flooded.
- 26 ftBased on NWC stage-based categorical flood inundation mapping, at this height water will begin flooding the outfields of the 2 easternmost ball fields at the Northwest Jefferson County Sports Complex.
- 22.4 ftAt this level, Twin Rivers Bridge Road must be closed.
- 20.5 ftBurgan Grove Road begins flooding near Cottage Grove Road, cutting off access to Cottage Grove Road. Highway W near Hoene Spring is closed as water crosses the pavement.
- 19.3 ftSouth Byrnesville Road begins flooding near this level.
- 19.1 ftBackyards and one basement along Burgan Grove Road 2 miles west of House Springs begin to flood.
- 19 ftDutch Creek Road south of Byrnesville and Byrnesville Road near John McKeever Road north of Byrnesville begin to flood.
- 18.1 ftState Highway BB southeast of Cedar Hill will be closed near this height.
- 18 ftCedar Hill Road at Cedar Hill and Klondike Road south of Cedar Hill begin to flood near this height.
- 15.5 ftRockford Beach Park at the Highway MM bridge begins flooding.
Highest crests on record
- 30.2 ft — August 21, 1915
- 30.09 ft — May 1, 2017
- 29.37 ft — September 25, 1993
- 27.61 ft — November 16, 1993
- 27.57 ft — April 12, 1994
Recent crests: 22.22 ft (March 7, 2026) · 18.62 ft (April 21, 2025) · 23.93 ft (April 7, 2025) · 27.57 ft (November 6, 2024) · 19.7 ft (August 5, 2023)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (BYRM7); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.