Millstone River at Griggstown, NJ
River level and flood forecast · Somerset County
The river is 0.5 ft below flood stage (10 ft).
The last 7 days and the forecast
NWS forecast issued Sun, Dec 31, 7 PM. Forecasts change as rain falls and as upstream water arrives.
Get flood alerts for this river
An email when the National Weather Service forecasts Millstone River at Griggstown to flood, when it floods, and when it's over.
Flood stages
| Major flood stage | 15 ft |
| Moderate flood stage | 12 ft |
| Flood stage | 10 ft |
| Action stage | 9.5 ft |
| Record crest (August 28, 2011) | 24.21 ft |
What floods at each level
From the National Weather Service, highest first.
- 15 ftRiver Road flooding expands. The road closes between Grist Mill Drive and the Millstone Causway. Canal Road in Franklin Township floods.
- 12 ftRiver Road flooding expands near the Griggstown Causeway and begins south of Dead Tree Run Road.
- 10 ftRiver Road in Montgomery Township begins to flood near the Griggstown Causeway.
- 9.5 ftGriggstown Causeway is closed.
Highest crests on record
- 24.21 ft — August 28, 2011
- 23.36 ft — September 2, 2021
- 23.2 ft — September 16, 1999
- 22.7 ft — August 28, 1971
- 22.16 ft — April 16, 2007
Recent crests: 12.01 ft (July 10, 2026) · 10.98 ft (March 7, 2026) · 15.96 ft (January 10, 2024) · 13.11 ft (December 29, 2023) · 16.49 ft (December 19, 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 (GTNN4); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.