St. Marys River at Great Mills
Maryland — Water Level & Flood Stage
Located in St. Marys County, Maryland on the St. Marys River. Live water level data from USGS gauge 01661500, updated every 15 minutes.
Current Water Level
Gage Height
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Streamflow
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Last Reading
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Flood Stages
Major Flood
10 ft
Moderate Flood
8 ft
Minor Flood
7 ft
Action Stage
5 ft
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
What Floods at Each Level
10 ft
Widespread flooding is occurring in Great Mills with water approaching homes and businesses.
8 ft
Indian Bridge Road begins to flood as flooding becomes more widespread in Great Mills.
7 ft
Flat Iron Road begins to flood with water in some yards in Great Mills.
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 19, 1969 | 13.34 ft | 7,950 cfs |
| Aug 19, 1969 | 13.34 ft | 7,950 cfs |
| Aug 28, 2011 | 12.98 ft | 6,960 cfs |
| Aug 28, 2011 | 12.98 ft | 6,960 cfs |
| Sep 15, 1999 | 12.82 ft | 6,560 cfs |
About This Gauge
USGS Site
NWS LID
GMRM2
River
St. Marys River
County
St. Marys, MD
Coordinates
38.2417°N, 76.5036°W
Get Flood Alerts for St. Marys 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 St. Marys River at Great Mills?
The St. Marys River at Great Mills gauge is maintained by USGS (site 01661500) 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 St. Marys River at Great Mills?
The NWS-defined flood stage for St. Marys River at Great Mills is 7 feet. Action stage begins at 5 feet. Moderate flooding starts at 8 feet, and major flooding at 10 feet.
How do I get alerts when St. Marys River rises?
Download StormCast free on Google Play, go to River Gauges, and add St. Marys River at Great Mills to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category — even when your screen is off.
Where is the St. Marys River at Great Mills gauge located?
The gauge is located in St. Marys County, Maryland at coordinates 38.2417°N, 76.5036°W. USGS site number: 01661500. Data is provided by the U.S. Geological Survey and the National Weather Service.
More Resources
Source & Notes
Data provided by: US Geological Survey, Observations courtesy of U.S. Geological Survey
- Stage may be affected by ice.