Major Flood
15 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Moderate Flood
10 ft
Minor Flood
9 ft
Action Stage
7 ft
What Floods at Each Level
13 ft
Washington Street and several businesses are flooded.
10 ft
The D&R Canal is flooded by the Millstone River.
9 ft
Flood stage reached with flooding now along River Road in Blackwells Mills and S. River Street in Millstone. Base of Route 533 bridge floods. River Road between Yorktown and Amsterdam is subject to closure. Canal Road near Suydam Road floods.
7 ft
Several more causeways are closed due to flooding.
6 ft
The Griggstown Causeway is closed due to flooding.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Aug 28, 2011 | 21.24 ft | 26,800 cfs |
| Sep 17, 1999 | 21.01 ft | 26,200 cfs |
| Sep 2, 2021 | 20.81 ft | 20,031 cfs |
Flood Inundation Map
NOAA has mapped what areas flood at different water levels for this gauge. View the interactive flood inundation map →
About This Gauge
USGS Site
NWS LID
BKWN4
River
Millstone River
County
Somerset, NJ
Coordinates
40.4750°N, 74.5758°W
Get Flood Alerts for Millstone River
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Millstone River at Blackwells Mills?
The Millstone River at Blackwells Mills gauge is maintained by USGS (site 01402000) and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Millstone River at Blackwells Mills?
The NWS-defined flood stage for Millstone River at Blackwells Mills is 9 feet. Action stage begins at 7 feet. Moderate flooding starts at 10 feet, and major flooding at 15 feet.
How do I get alerts when Millstone River rises?
Download StormCast free on Google Play, go to River Gauges, and add Millstone River at Blackwells Mills to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Millstone River at Blackwells Mills gauge located?
The gauge is located in Somerset County, New Jersey at coordinates 40.4750°N, 74.5758°W. USGS site number: 01402000. Data is provided by the U.S. Geological Survey and the National Weather Service.
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Source & Notes
Data provided by: US Geological Survey, Observations courtesy of U.S. Geological Survey