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St. Marys River at Great Mills — water level right now

St. Marys County, Maryland · NWS gauge GMRM2
Loading the latest reading…
–
current stage (ft)
 
7
minor flood stage
 
13.34
record crest
set 1969-08-20
–
flood status
official NWS category
Official NOAA forecast → USGS data → Full US flood map →

Flood stages at this gauge

Where the water stands right now against the four official thresholds:

action · 5
minor · 7
moderate · 8
major · 10
Flood stageLevel (ft)What it means
Major flood stage10extensive inundation and significant evacuations — a serious event
Moderate flood stage8some buildings and roads inundated; evacuations possible
Minor flood stage7low-lying roads and fields near the river start to flood
Action stage5water is approaching flood level — time to pay attention

Highest floods on record here

#Crest (ft)Datevs. minor flood stage
113.341969-08-20+6.34 above
212.982011-08-28+5.98 above
312.821999-09-16+5.82 above
412.081960-07-30+5.08 above
511.771955-08-13+4.77 above
611.572020-08-04+4.57 above
711.271998-02-05+4.27 above
811.211994-03-03+4.21 above
910.971979-02-25+3.97 above
1010.931985-09-27+3.93 above
1110.871958-08-25+3.87 above
1210.782010-09-30+3.78 above

Historic crests recorded at this gauge by the National Weather Service — the 12 highest on file.

Where this gauge is

The marker is this gauge; nearby gauges load live and are clickable.

Nearby river gauges

Patuxent River at Solomons Island (IN MLLW) 6 mi away · loading… St. George Creek at Straits Point (IN MLLW) 7 mi away · loading… St. Clement Creek near Clements 14 mi away · loading… Chesapeake Bay at Bishops Head (IN MLLW) 25 mi away · loading… Zekiah Swamp Run near Newtown 29 mi away · loading… Chesapeake Bay at Cambridge (IN MLLW) 33 mi away · loading…

Gauge details

NWS gauge IDGMRM2
USGS site01661500
CountySt. Marys
StateMaryland
NWS forecast officeSterling
River forecast centerMiddle Atlantic River Forecast Center
Coordinates38.242, -76.504
Time zoneEST5EDT
Turn Around, Don't Drown. Six inches of moving water can knock you off your feet and twelve inches can float a car. Never drive around barricades or into water of unknown depth — most flood deaths happen in vehicles.

Questions about St. Marys River at Great Mills

Is St. Marys River at Great Mills flooding right now?

The live reading at the top of this page answers that: the gauge is compared against its official NWS flood stages every 15 minutes. Minor flooding at this gauge begins at 7 ft. Blue means normal, yellow is action stage, orange minor, red moderate and dark red major flooding.

What is flood stage for St. Marys River at Great Mills?

major flood stage 10 ft, moderate flood stage 8 ft, minor flood stage 7 ft, action stage 5 ft. These are official National Weather Service thresholds set specifically for this gauge, not generic values.

What is the record flood at St. Marys River at Great Mills?

The highest crest on file at this gauge is 13.34 ft, reached on 1969-08-20 — that is 6.34 ft above minor flood stage. The full list of the highest crests is in the table on this page.

Where does this data come from?

From the NOAA National Water Prediction Service, the official U.S. river gauge network — a U.S. government work in the public domain. Live stage is refreshed every 15 minutes; flood thresholds and historic crests are refreshed monthly. For life-safety decisions follow NWS Sterling and local emergency management.