The monitoring network within this area

Hydrionis holds 2,143 values from 5 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.

5

Gauges

2,143

Values held

1899–2026

Record spans

Gauges within the Middle Clark Fork huc8 subbasin

5 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 Clark Fork at St. Regis MT

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1911–2025.

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	Clark Fork at St. Regis MT (m³/s)
1911	957
1912	1,172
1913	1,798
1914	991
1915	490
1916	1,501
1917	1,674
1918	1,371
1919	830
1920	909
1921	1,184
1922	1,337
1923	937
1929	923
1930	629
1931	450
1932	926
1933	1,416
1934	1,011
1935	776
1936	963
1937	484
1938	1,314
1939	739
1940	487
1941	340
1942	1,014
1943	1,169
1944	453
1945	677
1946	677
1947	1,546
1948	1,951
1949	1,356
1950	1,450
1951	1,181
1952	974
1953	1,297
1954	1,388
1955	1,031
1956	1,756
1957	1,113
1958	1,269
1959	1,218
1960	951
1961	1,121
1962	949
1963	810
1964	1,724
1965	1,144
1966	699
1967	1,382
1968	855
1969	1,036
1970	1,328
1971	1,393
1972	1,809
1973	524
1974	1,787
1975	1,583
1976	1,557
1977	320
1978	1,059
1979	1,093
1980	974
1981	1,359
1982	1,376
1983	1,036
1984	988
1985	799
1986	1,099
1987	651
1988	498
1989	932
1990	787
1991	985
1992	456
1993	869
1994	589
1995	838
1996	1,325
1997	1,951
1998	682
1999	1,127
2000	530
2001	564
2002	1,096
2003	1,254
2004	555
2005	643
2006	1,121
2007	668
2008	1,311
2009	1,209
2010	779
2011	1,572
2012	1,209
2013	937
2014	1,169
2015	490
2016	597
2017	988
2018	1,713
2019	1,218
2020	1,240
2021	912
2022	1,031
2023	980
2024	510
2025	561

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	1911–2025
Completeness	95.7% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1911–2025 holds no value: 1924 to 1928, 5 years with no reading. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1911 and is not continuous from it: 115 years separate the first value from the last, and 96% 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 Clark Fork at St. Regis 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. 1930–2025.

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	Clark Fork at St. Regis MT (mm)
1930	177
1931	108
1932	199
1933	277
1934	267
1935	167
1936	184
1937	117
1938	223
1939	168
1940	135
1941	124
1942	201
1943	323
1944	138
1945	172
1946	214
1947	297
1948	346
1949	245
1950	314
1951	319
1952	240
1953	230
1954	270
1955	241
1956	318
1957	234
1958	243
1959	318
1960	218
1961	206
1962	255
1963	215
1964	279
1965	340
1966	182
1967	273
1968	241
1969	267
1970	250
1971	312
1972	354
1973	130
1974	327
1975	331
1976	339
1977	116
1978	266
1979	206
1980	250
1981	246
1982	319
1983	209
1984	234
1985	188
1986	229
1987	125
1988	134
1989	205
1990	213
1991	210
1992	130
1993	183
1994	140
1995	229
1996	331
1997	377
1998	216
1999	246
2000	166
2001	133
2002	224
2003	210
2004	176
2005	168
2006	221
2007	186
2008	253
2009	242
2010	168
2011	345
2012	250
2013	170
2014	274
2015	183
2016	175
2017	280
2018	346
2019	237
2020	254
2021	198
2022	213
2023	190
2024	139
2025	154

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	1930–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1930 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

The snow standing above this water

2 automated snow stations sit inside this drainage area, weighing the snowpack rather than measuring how deep it is.

2,172

Fullest snowpack recorded at Hoodoo Basin, in 1972 (mm of water)

524

Thinnest, in 1977 (mm of water)

April

Month the pack is usually at its fullest

July

Month the pack has gone by, in half of years

Peak snowpack at Hoodoo Basin

Water years 1967–2026. 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	Hoodoo Basin (mm)
1967	1,419
1968	1,221
1969	1,296
1970	1,342
1971	1,795
1972	2,172
1973	858
1974	1,821
1975	1,355
1976	1,401
1977	524
1978	1,226
1979	1,151
1980	1,069
1981	925
1982	1,545
1983	1,114
1984	919
1985	1,149
1986	1,019
1987	847
1988	948
1989	1,100
1990	1,046
1991	1,365
1992	896
1993	845
1994	756
1995	1,023
1996	1,382
1997	1,886
1998	833
1999	1,587
2000	993
2001	602
2002	1,451
2003	1,023
2004	841
2005	720
2006	1,254
2007	893
2008	1,350
2009	1,020
2010	644
2011	1,464
2012	1,225
2013	986
2014	1,393
2015	696
2016	880
2017	1,120
2018	1,230
2019	979
2020	1,022
2021	899
2022	1,070
2023	971
2024	717
2025	938
2026	1,136

Read against the river

Hoodoo Basin and Clark Fork above Missoula MT both sit in this drainage area, and their records overlap by 57 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 Middle Clark Fork and what each holds
Gauge	Measures	Values	Record
Clark Fork at St. Regis MT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	339	1911–2026
Clark Fork below Missoula MT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	321	1929–2026
Clark Fork above Missoula MT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	320	1929–2026
St. Regis River near St. Regis, MT	catchment area, annual maximum river flow	48	1911–2026
Rattlesnake Creek at Missoula MT	catchment area, annual maximum river flow	11	1899–2026

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 — 17010204. 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
Clark Fork at St. Regis 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
Clark Fork below Missoula 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
Clark Fork above Missoula 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. Regis River near St. Regis, 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
Rattlesnake Creek at Missoula 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	128	yes, 20 or more
Values held	2,143	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-12354500.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), Middle Clark Fork gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-middle-clark-fork/

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 Middle Clark Fork 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 confidence2025-05-12

Source: USGS — National Water Information System, USGS site 12354500, 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.