The monitoring network within this area

Hydrionis holds 593 values from 2 gauges within it. Discharge is a property of a gauge and its reach, not of this drainage area, so this page reports the network and its records rather than a single figure.

Gauges

593

Values held

1921–2026

Record spans

Gauges within the St. Marys huc8 subbasin

2 monitoring points, positioned as the publisher records them.

Flood peaks, as measured

This gauge's flood record, as measured. Unlike a daily mean it is the discharge at the moment the river was highest, which is the figure flood frequency analysis is built on.

Largest measured flow of each year at ST. MARYS RIVER NEAR MACCLENNY, FL

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1927–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Published by the gauge's own operator from its sub-daily record; Hydrionis stores the figure rather than recomputing it. A year the gauge did not cover produces no value rather than a low one, and the gaps are stated below the chart. A peak is a property of this gauge and its reach: a larger flood upstream or downstream of it is not in this series.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	ST. MARYS RIVER NEAR MACCLENNY, FL (m³/s)
1927	86.9
1928	739
1929	141
1931	58.9
1932	138
1933	149
1934	234
1935	141
1936	43.6
1937	171
1938	224
1940	63.7
1941	43.0
1942	193
1943	41.1
1944	163
1946	177
1947	796
1948	753
1949	233
1950	753
1952	51.3
1953	159
1955	21.6
1956	56.9
1957	238
1958	227
1959	283
1960	220
1961	163
1962	69.7
1963	229
1964	736
1966	148
1967	142
1968	105
1969	78.2
1970	411
1971	177
1972	110
1973	793
1974	157
1975	127
1976	58.9
1977	94.9
1978	130
1979	130
1980	197
1981	60.0
1982	91.2
1983	131
1984	233
1985	140
1986	163
1987	177
1988	262
1989	53.5
1990	53.5
1991	138
1992	76.7
1994	135
1996	55.5
1998	416
2000	40.2
2001	49.3
2002	70.5
2003	314
2004	555
2005	150
2007	109
2008	580
2009	174
2010	61.2
2011	39.6
2012	985
2013	88.9
2014	198
2016	98.5
2017	682
2018	77.0
2020	158
2021	261
2022	121
2023	71.6
2024	419
2025	96.0

About this series

Everything below is a property of the data rather than a rating of it. There is deliberately no single confidence score: how much a gap matters depends on what you are about to do with the series, and only you know that.

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Measured
Period held	1927–2025
Completeness	86.9% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	13 separate periods inside 1927–2025 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1927 and is not continuous from it: 99 years separate the first value from the last, and 87% of the years between them are held. The span is not the record.
Last read from the publisher	2026-10-01
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

How much of the rain came back out

A discharge in cubic metres per second cannot be compared with anything: the larger number may only mean the larger catchment. Divided by the area draining to the gauge it becomes a depth of water over that land, which answers a question a reader already has — of the rain that fell here, how much came back out as river?

Water leaving the catchment above ST. MARYS RIVER NEAR MACCLENNY, FL, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1927–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Computed by Hydrionis from the published annual mean flow and the catchment area the station's own publisher states. It is not a water balance: the difference between rainfall and runoff is not evaporation alone but also change in groundwater storage, water abstracted and taken elsewhere, and water imported by transfer schemes — which is why a catchment can yield more runoff than the rain that fell on it without anything being measured wrongly. A different area figure rescales every value here by the ratio between them.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	ST. MARYS RIVER NEAR MACCLENNY, FL (mm)
1927	187
1928	679
1929	611
1930	464
1931	198
1932	212
1933	336
1934	163
1935	203
1936	134
1937	390
1938	274
1939	235
1940	143
1941	225
1942	413
1943	57.0
1944	502
1945	405
1946	458
1947	905
1948	685
1949	261
1950	447
1951	60.0
1952	110
1953	429
1954	88.0
1955	46.0
1956	95.0
1957	295
1958	306
1959	574
1960	406
1961	229
1962	127
1963	292
1964	887
1965	438
1966	586
1967	218
1968	148
1969	333
1970	561
1971	252
1972	328
1973	596
1974	313
1975	356
1976	186
1977	345
1978	300
1979	340
1980	288
1981	128
1982	260
1983	406
1984	465
1985	251
1986	331
1987	415
1988	341
1989	117
1990	81.0
1991	512
1992	295
1993	214
1994	385
1995	195
1996	298
1997	309
1998	572
1999	61.0
2000	58.0
2001	52.0
2002	112
2003	437
2004	501
2005	431
2006	124
2007	114
2008	362
2009	215
2010	120
2011	40.0
2012	423
2013	231
2014	496
2015	211
2016	103
2017	389
2018	333
2019	157
2020	278
2021	520
2022	282
2023	226
2024	357
2025	116

About this series

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Derived Computed by Hydrionis
Period held	1927–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1927 to 2025 is held.
Inputs last read	2026-10-01 · when the records this was computed from were last read from their publishers
Calculation date	2026-08-24 · when the calculation method was last versioned, not a reading of any publisher
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

Every gauge Hydrionis holds within this area

Gauges within the St. Marys and what each holds
Gauge	Measures	Values	Record
ST. MARYS RIVER NEAR MACCLENNY, FL	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	334	1926–2026
NORTH PRONG ST. MARYS RIVER AT MONIAC, GA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	259	1921–2026

How these gauges were attached to this water

Assigned by the publisher to a numbered basin Every gauge here is assigned to this drainage area by its own publisher, which issues the area an official code — 03070204. A drainage area is not a river: it contains the tributaries as well as the main channel, and a gauge in it may be on any of them.

What each gauge’s link to this water rests on
Gauge	Evidence	Established
ST. MARYS RIVER NEAR MACCLENNY, FL	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
NORTH PRONG ST. MARYS RIVER AT MONIAC, GA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02

What this record holds

Hydrionis decides which waters get a page, and which of those are offered to search, from what is actually held rather than from how the page reads. Five signals are counted; this record has 3 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	2	no
Years spanned	106	yes, 20 or more
Values held	593	no
Distinct measurements	5	yes, 2 or more
Publishers measuring it	2	yes, 2 or more
Official identifiers	1	recorded, not counted

Use this data

Machine-readable JSON /api/v1/observations/by-subject/gauge-usgs-02231000.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

No bulk download is offered here, which is a licence position rather than a product one: at least one contributing publisher does not permit redistribution. The values can be read on the page, cited, and pointed to at source.

Attribution and citation

Suggested citation for Hydrionis

Hydrionis (2026), St. Marys gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-st-marys-03070204/

Cite Hydrionis where you rely on values Hydrionis computed, on the method that produced them, or on the compilation itself. The underlying measurements remain the publishers’ and their attribution requirements apply to you directly.

Recommended, not required. Hydrionis does not claim rights over unmodified public data it relayed, and doing arithmetic on somebody else’s measurements does not make them Hydrionis’s. Cite the version and the access date: the St. Marys gauge records changes as publishers release and as methods are revised, and a citation without both cannot be checked later. Full guidance is on cite and reuse.

None of the contributing licences requires attribution. Crediting the publishers is still good practice and they are listed above.

Where these figures come from

MeasuredHigh confidence2025-03-13

Source: USGS — National Water Information System, USGS site 02231000, annual peak streamflow. Licence: Open.

Method: The instantaneous maximum discharge of each water year as published by USGS, dated to the day it occurred. One value per October-to-September water year; where the publisher lists both a systematic and a historic peak for a year, the larger is the annual maximum. Values the publisher marks as maximum daily averages are not held here, because they are not instantaneous peaks. Values marked as bounded rather than measured are held as censored observations carrying the bound. Cubic feet per second are converted to cubic metres per second and the publisher unit is recorded alongside.

Rating curves are extrapolated at extreme discharges, so the largest values in a peak series carry the largest measurement uncertainty. Data from the U.S. Geological Survey National Water Information System, a work of the United States government and therefore in the public domain.

Retrieved 1 October 2026.