The monitoring network within this area

Hydrionis holds 1,250 values from 3 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.

3

Gauges

1,250

Values held

1902–2026

Record spans

Gauges within the St. Marys huc8 subbasin

3 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 Swiftcurrent Creek at Many Glacier MT

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1913–2023.

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	Swiftcurrent Creek at Many Glacier MT (m³/s)
1913	32.6
1914	19.5
1915	17.0
1916	43.9
1917	34.5
1918	36.2
1919	31.1
1920	28.9
1921	31.1
1922	24.6
1923	23.1
1924	21.8
1925	29.4
1926	13.9
1927	31.1
1928	31.7
1929	25.0
1930	25.1
1931	31.4
1932	38.5
1933	38.5
1934	36.2
1935	30.3
1936	29.4
1937	63.7
1938	32.0
1939	30.0
1940	19.7
1941	14.2
1942	29.4
1943	46.2
1944	14.3
1945	23.9
1946	22.6
1947	20.0
1948	35.4
1949	21.5
1950	34.3
1951	28.6
1953	37.4
1954	36.2
1955	27.0
1956	31.1
1957	23.2
1958	23.6
1959	28.6
1960	27.4
1961	28.6
1962	17.1
1963	23.4
1964	190
1965	39.4
1966	23.4
1967	30.6
1968	27.9
1969	23.0
1970	31.7
1971	27.9
1972	32.6
1973	38.8
1974	34.8
1975	93.7
1976	28.6
1977	14.9
1978	26.8
1979	30.3
1980	23.1
1981	26.1
1982	24.4
1983	29.4
1984	33.4
1985	37.9
1986	28.6
1987	23.6
1988	19.4
1989	30.6
1991	42.5
1992	24.1
1993	19.6
1994	20.1
1995	89.2
1996	32.3
1997	41.1
1998	25.4
1999	25.3
2001	21.3
2002	35.4
2003	33.4
2004	21.9
2005	25.3
2006	39.9
2008	32.0
2009	22.5
2010	21.9
2011	34.3
2012	30.3
2013	39.1
2014	32.6
2015	26.5
2016	19.5
2017	25.5
2019	26.0
2020	32.8
2021	27.5
2022	41.6
2023	24.9

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	1913–2023
Completeness	95.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	5 separate periods inside 1913–2023 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1913 and is not continuous from it: 111 years separate the first value from the last, and 95% 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. Mary River near Babb MT, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1951–2024.

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. Mary River near Babb MT (mm)
1951	1,306
1952	817
1953	1,114
1954	1,303
1955	947
1956	1,052
1957	878
1958	844
1959	1,214
1960	795
1961	950
1962	825
1963	897
1964	1,163
1965	1,035
1966	920
1967	1,042
1968	983
1969	888
1970	946
1971	1,138
1972	1,206
1973	706
1974	1,164
1975	1,298
1976	980
1977	562
1978	1,075
1979	786
1980	917
1981	932
1982	889
1983	744
1984	744
1985	958
1986	861
1987	767
1988	688
1989	1,096
1990	1,015
1991	1,184
1992	668
1993	755
1994	740
1995	1,162
1996	1,004
1997	1,119
1998	843
1999	1,035
2000	766
2001	546
2002	1,163
2003	740
2004	862
2005	816
2006	1,043
2007	780
2008	954
2009	778
2010	860
2011	1,230
2012	1,152
2013	963
2014	1,130
2015	778
2016	941
2017	1,017
2018	1,011
2019	827
2020	965
2021	915
2022	1,029
2023	722
2024	760

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	Derived Computed by Hydrionis
Period held	1951–2024
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1951 to 2024 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

The snow standing above this water

1 automated snow station sits inside this drainage area, weighing the snowpack rather than measuring how deep it is.

639

Fullest snowpack recorded at Many Glacier, in 1997 (mm of water)

74

Thinnest, in 2026 (mm of water)

March

Month the pack is usually at its fullest

May

Month the pack has gone by, in half of years

Peak snowpack at Many Glacier

Water years 1977–2026. Each point is the fullest month of that snow season.

A water year runs October to September and is named for the year it ends, so the snow of one winter stays in one point. The value is the fullest month, not the fullest day: a pack that peaked sharply mid-month reads lower here than a single measurement taken at the right moment would.

View the data behind this chart

Underlying data
Period	Many Glacier (mm)
1977	251
1978	493
1979	418
1980	412
1981	303
1982	559
1983	389
1984	282
1985	439
1986	232
1987	299
1988	250
1989	389
1990	444
1991	545
1992	234
1993	293
1994	384
1995	244
1996	320
1997	639
1998	296
1999	461
2000	348
2001	299
2002	488
2003	284
2004	274
2005	78.0
2006	277
2007	234
2008	393
2009	318
2010	208
2011	560
2012	426
2013	264
2014	401
2015	122
2016	147
2017	407
2018	485
2019	263
2020	336
2021	269
2022	353
2023	311
2024	197
2025	200
2026	74.0

Read against the river

Many Glacier and Swiftcurrent Creek at Many Glacier MT both sit in this drainage area, and their records overlap by 47 years. That is the span the two have in common, not a count of years both actually hold — either record may have gaps inside it. The two are shown separately rather than on one axis: millimetres of stored water and cubic metres per second are not commensurable, and a difference between them would mean nothing.

Being in the same drainage area does not put the snowpack upstream of the gauge. A subbasin is an area, and snow on one tributary can join the river below a gauge on another — so a weak relationship here may say more about which tributary was measured than about the snow.

Every gauge Hydrionis holds within this area

Gauges within the St. Marys and what each holds
Gauge	Measures	Values	Record
Swiftcurrent Creek at Many Glacier MT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	284	1913–2026
St. Mary River near Babb MT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	273	1902–2026
Swiftcurrent Creek at Sherburne MT	catchment area, annual maximum river flow	93	1913–2026

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 — 09040001. 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
Swiftcurrent Creek at Many Glacier MT	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
St. Mary River near Babb MT	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
Swiftcurrent Creek at Sherburne MT	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 5 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	3	yes, 3 or more
Years spanned	125	yes, 20 or more
Values held	1,250	yes, 1000 or more
Distinct measurements	6	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-05014500.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/

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 confidence2023-06-10

Source: USGS — National Water Information System, USGS site 05014500, 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.