Major Flood
14 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
12 ft
Minor Flood
10 ft
Action Stage
5 ft
What Floods at Each Level
17 ft
Water overflows the overlooks at Great Falls National Park and approaches the lower level of the visitors center. Most of the C&O Canal towpath downstream of Pennyfield is flooded. There is approximately a foot of water in the clubhouse on Sycamore Island.
16 ft
Water reaches the clubhouse on Sycamore Island.
15 ft
Most of the C&O Canal towpath from Pennyfield downstream is flooded.
14 ft
Significant portions of the C&O Canal towpath are flooded. The Blockhouse Point Park is flooded. Water reaches the retaining wall at Overlook 1 at Great Falls National Park but does not overtop it.
12 ft
The C&O Canal overflows at the Great Falls Tavern. Water covers the towpath in many areas.
11.5 ft
Water covers the towpath in multiple spots between the Washington Aqueduct Dam and Pennyfield Lock, mileposts 15 to 19 on the C&O Canal.
11 ft
Water covers the towpath between Swains Lock and Pennyfield Lock, mileposts 17 to 19 on the C&O Canal.
10 ft
Water begins to overflow the banks into low lying areas on the Maryland side of the river near Little Falls. Water begins to enter the canoe shed at Sycamore Island.
9 ft
Several trails on both sides of the river between Great Falls and the Chain Bridge are flooded and will be closed.
7 ft
Upper portions of the River Trail at Great Falls National Park begin to flood and will be closed.
5.5 ft
Water reaches the top of the ferry landing for Sycamore Island. Ferry service to the island will likely be suspended.
5 ft
Portions of the Potomac Heritage Trail begin to flood. Water begins to affect portions of the Billy Goat Trail between Great Falls and Carderock. These trails will be closed.
4.5 ft
The river reaches danger level for boaters, as defined by the State of Maryland. Conditions for boating will be extremely hazardous.
3.5 ft
The river reaches caution level for boaters, as defined by the State of Maryland. Fast moving water and changing currents will be experienced.
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 |
|---|---|---|
| Mar 19, 1936 | 28.1 ft | 484,000 cfs |
| Oct 17, 1942 | 26.88 ft | 447,000 cfs |
| Apr 27, 1937 | 23.3 ft | 347,000 cfs |
About This Gauge
USGS Site
NWS LID
BRKM2
River
Potomac River
County
Montgomery, MD
Coordinates
38.9497°N, 77.1278°W
Get Flood Alerts for Potomac 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 Potomac River near Washington DC (Little Falls)?
The Potomac River near Washington DC (Little Falls) gauge is maintained by USGS (site 01646500) 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 Potomac River near Washington DC (Little Falls)?
The NWS-defined flood stage for Potomac River near Washington DC (Little Falls) is 10 feet. Action stage begins at 5 feet. Moderate flooding starts at 12 feet, and major flooding at 14 feet.
How do I get alerts when Potomac River rises?
Download StormCast free on Google Play, go to River Gauges, and add Potomac River near Washington DC (Little Falls) 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 Potomac River near Washington DC (Little Falls) gauge located?
The gauge is located in Montgomery County, Maryland at coordinates 38.9497°N, 77.1278°W. USGS site number: 01646500. Data is provided by the U.S. Geological Survey and the National Weather Service.
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Source & Notes
Data provided by: Observations courtesy of U.S. Geological Survey
- Stage may be affected by ice.