St Marys River at Great Mills water level

Name: St Marys River at Great Mills water level (U.S. Geological Survey)
Creator: U.S. Geological Survey
License: https://www.usgs.gov/information-policies-and-instructions/copyrights-and-credits

River gauge, St Marys River, Maryland, United States

Directions

Below flood stage

Water level

1.55ft Down 0.07 ft over the last 24 hours

Measured Oct 20, 2026, 10:15 AM EDT (54 min ago)

Flow: 10.5 cfs

History

7 days

Water level Minor flood stage

What this means

Water levels are unremarkable at St Marys River at Great Mills, where the gauge shows 1.55 ft.

It is 5.45 ft below the flood stage of 7.00 ft.

It is still going down, by 0.07 ft over the past 24 hours. The 30-day range is 1.55 ft – 2.24 ft.

Fall is often low-water season on rivers, until steadier rain returns.

Judged against the official flood stage for this gauge. How to read levels

Key numbers

Highest on record: 13.34 ftAugust 20, 1969

Paddling and fishing conditions

Most paddlers and anglers will find the river in good shape at this stage.

For reference, flood stage is 7.00 ft.

What happens at each level

10.00 ft: Widespread flooding is occurring in Great Mills with water approaching homes and businesses.
8.00 ft: Indian Bridge Road begins to flood as flooding becomes more widespread in Great Mills.
7.00 ft: Flat Iron Road begins to flood with water in some yards in Great Mills.
1.55 ft: Right now

Impact statements from the U.S. National Weather Service.

Highest crests on record

Rank	Level	Date
1	13.34 ft	August 20, 1969
2	12.98 ft	August 28, 2011
3	12.82 ft	September 16, 1999
4	12.08 ft	July 30, 1960
5	11.77 ft	August 13, 1955
6	11.57 ft	August 4, 2020
7	11.27 ft	February 5, 1998
8	11.21 ft	March 3, 1994
9	10.97 ft	February 25, 1979
10	10.93 ft	September 27, 1985

Weather at the gauge

Rain in the last 3 days: 0.56 in. Rain that falls upstream can take hours or days to show up at a river gauge.

20 Tue 64° 47° – Wind 14 mph

21 Wed 59° 49° – Wind 14 mph

22 Thu 67° 42° – Wind 10 mph

23 Fri 62° 49° – Wind 11 mph

24 Sat 62° 44° – Wind 6 mph

25 Sun 64° 45° – Wind 6 mph

26 Mon 68° 48° – Wind 6 mph

Forecast: Open-Meteo

Sunrise 07:20 AM Sunset 06:23 PM Daylight 11 hr, 2 min First quarter 69%

Map

Nearby gauges

Gauge	Level	Compared with normal	24 hours	Distance
St Clements Creek near ClementsRiver gauge, St Clements Creek	−0.09 ft	Below flood stage	−0.13 ft	14 mi
Zekiah Swamp Run near NewtownRiver gauge, Zekiah Swamp Run	1.30 ft	Below flood stage	−0.21 ft	29 mi
Piscataway Creek near TappahannockRiver gauge, Piscataway Creek	6.8 cfs	Low	−0.4 cfs	33 mi
Chicamacomico River near SalemRiver gauge, Chicamacomico River	6.7 cfs	Normal	−0.5 cfs	39 mi
Mattawoman Creek near PomonkeyRiver gauge, Mattawoman Creek	2.38 ft	Below flood stage	−0.19 ft	39 mi
Piscataway Creek at PiscatawayRiver gauge, Piscataway Creek	2.42 ft	Below flood stage	−0.05 ft	41 mi
Western Branch at Upper MarlboroRiver gauge, Western Branch	1.84 ft	Below flood stage	−0.08 ft	42 mi
Mattaponi River near BeulahvilleRiver gauge, Mattaponi River	4.82 ft	Below flood stage	−0.06 ft	44 mi

Questions and answers

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

The official flood stage is 7.00 ft. The level is currently 5.45 ft below it.

Is gage height the same as water depth?

No. Gage height is measured from a fixed reference point chosen by the agency, so a reading of 10 ft does not mean the river is 10 ft deep.

What is the water level of St Marys River at Great Mills today?

On Oct 20, 2026, 10:15 AM EDT, the water level was 1.55 ft. Down 0.07 ft over the last 24 hours.

Is St Marys River at Great Mills rising or falling?

Down 0.07 ft over the last 24 hours.

Is the level of St Marys River at Great Mills normal?

Below flood stage. Judged against the official flood stage for this gauge.

What is the highest water level ever recorded at St Marys River at Great Mills?

The highest level on record is 13.34 ft on August 20, 1969.

How often is this data updated?

The U.S. Geological Survey publishes a new reading every 15 minutes. This page refreshes within minutes of each update.

For specialists

Station codes, datum, parameters, data quality and downloads

Operator: U.S. Geological Survey
Station code: usgs:01661500 (Agency page)
Coordinates: 38.24175, -76.50367 (WGS84)
Vertical datum: NAVD88
Update interval: every 15 minutes
Licence: Public domain. Data: U.S. Geological Survey (USGS), provisional data subject to revision

Published series

Parameter	Last value	Time (UTC)	Quality
Water level	1.55 ft	2026-10-20 14:15	Provisional
Flow	10.5 cfs	2026-10-20 14:15	Provisional

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How to cite

U.S. Geological Survey: St Marys River at Great Mills (usgs:01661500). Accessed October 20, 2026 via Nivelmap, https://nivelmap.com/en/united-states/maryland/st-marys-river-at-great-mills

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.

Readings are provisional, can be delayed or wrong and are not a flood warning. Read the disclaimer