The monitoring network within this area

Hydrionis holds 1,712 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

1,712

Values held

1898–2026

Record spans

Gauges within the Portneuf 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 PORTNEUF RIVER AT POCATELLO ID

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1919–2025.

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	PORTNEUF RIVER AT POCATELLO ID (m³/s)
1919	23.6
1929	16.7
1931	13.3
1932	17.5
1933	14.6
1934	8.50
1938	20.2
1940	13.0
1941	16.5
1942	20.6
1943	25.3
1945	21.9
1946	29.4
1947	15.7
1948	20.8
1949	19.4
1950	25.5
1951	17.8
1952	29.7
1953	17.6
1954	14.4
1955	10.6
1956	18.7
1957	27.5
1958	21.6
1959	14.5
1960	21.5
1961	18.3
1962	84.7
1963	71.1
1964	21.9
1966	20.1
1967	18.1
1968	17.0
1969	32.0
1970	24.4
1971	44.7
1972	35.7
1973	27.8
1974	36.5
1975	43.6
1976	39.4
1978	23.2
1979	16.0
1980	33.7
1982	35.7
1983	56.4
1984	81.3
1985	37.1
1986	41.3
1987	21.8
1988	14.8
1989	24.9
1990	14.3
1991	15.5
1992	15.1
1993	30.6
1994	20.7
1995	17.4
1996	36.2
1997	36.8
2000	15.8
2002	12.5
2004	13.6
2007	23.7
2008	12.9
2009	19.6
2010	14.2
2011	34.3
2012	22.9
2013	13.6
2014	19.0
2015	9.15
2016	17.5
2017	31.4
2018	27.9
2019	27.8
2020	17.6
2021	10.1
2022	10.0
2023	37.1
2024	28.9
2025	17.3

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	1919–2025
Completeness	77.6% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	12 separate periods inside 1919–2025 hold no value. The longest runs from 1920 to 1928 — 9 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1919 and is not continuous from it: 107 years separate the first value from the last, and 78% 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 PORTNEUF RIVER AT POCATELLO ID, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1913–2025.

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	PORTNEUF RIVER AT POCATELLO ID (mm)
1913	75.0
1914	109
1915	59.0
1916	75.0
1918	76.0
1919	69.0
1920	78.0
1921	115
1922	100
1923	88.0
1924	60.0
1925	80.0
1926	58.0
1927	81.0
1928	69.0
1929	70.0
1930	49.0
1931	41.0
1932	62.0
1933	55.0
1934	29.0
1935	43.0
1936	64.0
1937	56.0
1938	69.0
1939	53.0
1940	44.0
1941	57.0
1942	66.0
1943	85.0
1944	65.0
1945	92.0
1946	95.0
1947	62.0
1948	77.0
1949	69.0
1950	110
1951	74.0
1952	86.0
1953	70.0
1954	50.0
1955	47.0
1956	59.0
1957	73.0
1958	71.0
1959	54.0
1960	48.0
1961	44.0
1962	70.0
1963	65.0
1964	75.0
1965	92.0
1966	50.0
1967	69.0
1968	63.0
1969	93.0
1970	77.0
1971	129
1972	134
1973	95.0
1974	110
1975	126
1976	110
1977	48.0
1978	81.0
1979	57.0
1980	101
1981	62.0
1982	117
1983	171
1984	194
1985	107
1986	167
1987	67.0
1988	47.0
1989	59.0
1990	44.0
1991	50.0
1992	29.0
1993	75.0
1994	40.0
1995	64.0
1996	94.0
1997	125
1998	110
1999	94.0
2000	58.0
2001	37.0
2002	42.0
2003	30.0
2004	36.0
2005	56.0
2006	96.0
2007	48.0
2008	44.0
2009	65.0
2010	51.0
2011	99.0
2012	52.0
2013	37.0
2014	40.0
2015	36.0
2016	51.0
2017	109
2018	74.0
2019	85.0
2020	63.0
2021	39.0
2022	40.0
2023	94.0
2024	86.0
2025	58.0

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	Derived Computed by Hydrionis
Period held	1913–2025
Completeness	99.1% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1913–2025 holds no value: 1917. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1913 and is not continuous from it: 113 years separate the first value from the last, and 99% of the years between them are held. The span is not the record.
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

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

687

Fullest snowpack recorded at Wildhorse Divide, in 1982 (mm of water)

162

Thinnest, in 2026 (mm of water)

March

Month the pack is usually at its fullest

June

Month the pack has gone by, in half of years

Peak snowpack at Wildhorse Divide

Water years 1982–2026. 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	Wildhorse Divide (mm)
1982	687
1986	450
1987	241
1988	257
1989	506
1990	282
1991	352
1992	169
1993	488
1994	280
1995	372
1996	526
1997	606
1998	546
1999	466
2000	410
2001	294
2002	435
2003	269
2004	515
2005	308
2006	606
2007	292
2008	433
2009	459
2010	285
2011	515
2012	251
2013	254
2014	272
2015	237
2016	354
2017	448
2018	267
2019	476
2020	337
2021	292
2022	261
2023	653
2024	548
2025	521
2026	162

Read against the river

Wildhorse Divide and PORTNEUF RIVER AT TOPAZ ID both sit in this drainage area, and their records overlap by 43 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 Portneuf and what each holds
Gauge	Measures	Values	Record
PORTNEUF RIVER AT POCATELLO ID	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	347	1898–2026
PORTNEUF RIVER AT TOPAZ ID	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	321	1913–2026
PORTNEUF RIVER NR PEBBLE ID	catchment area, annual maximum river flow	10	1969–2026

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 — 17040208. 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
PORTNEUF RIVER AT POCATELLO ID	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
PORTNEUF RIVER AT TOPAZ ID	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
PORTNEUF RIVER NR PEBBLE ID	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 4 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	129	yes, 20 or more
Values held	1,712	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-13075500.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), Portneuf gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-portneuf/

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 Portneuf 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 confidence2025-04-13

Source: USGS — National Water Information System, USGS site 13075500, 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.