The monitoring network within this area

Hydrionis holds 998 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.

Gauges

998

Values held

1903–2026

Record spans

Gauges within the Pemigewasset River 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 PEMIGEWASSET RIVER AT PLYMOUTH, NH

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1904–2024.

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	PEMIGEWASSET RIVER AT PLYMOUTH, NH (m³/s)
1904	425
1905	524
1906	561
1907	450
1909	719
1910	365
1911	493
1912	430
1913	776
1914	892
1915	566
1916	481
1917	544
1919	623
1920	640
1922	697
1923	980
1924	631
1925	773
1926	504
1927	1,699
1929	648
1930	578
1931	411
1932	515
1933	564
1934	640
1935	481
1936	1,852
1937	450
1938	1,441
1940	719
1942	722
1943	357
1945	456
1947	501
1948	663
1950	793
1952	776
1953	1,266
1954	824
1955	411
1956	450
1957	211
1959	425
1961	248
1962	493
1964	609
1966	256
1968	685
1969	708
1971	481
1972	459
1973	1,348
1975	711
1976	810
1977	623
1979	634
1980	623
1981	651
1982	651
1983	447
1984	835
1985	323
1986	425
1987	1,506
1988	793
1989	663
1990	626
1991	490
1993	631
1994	530
1995	269
1996	702
1998	694
1999	793
2000	875
2002	750
2003	671
2005	705
2006	648
2008	572
2009	476
2011	1,164
2012	493
2014	776
2016	558
2017	824
2019	881
2020	827
2021	501
2022	830
2023	1,328
2024	646

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	1904–2024
Completeness	77.7% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	27 separate periods inside 1904–2024 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1904 and is not continuous from it: 121 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 PEMIGEWASSET RIVER AT PLYMOUTH, NH, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1904–2025.

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	PEMIGEWASSET RIVER AT PLYMOUTH, NH (mm)
1904	818
1905	733
1906	667
1907	899
1908	696
1909	752
1910	683
1911	670
1912	774
1913	797
1914	667
1915	782
1916	877
1917	798
1918	739
1919	794
1920	915
1921	624
1922	838
1923	767
1924	793
1925	889
1926	637
1927	779
1928	780
1929	734
1930	672
1931	508
1932	817
1933	606
1934	748
1935	625
1936	999
1937	856
1938	894
1939	660
1940	721
1941	497
1942	678
1943	873
1944	580
1945	981
1946	768
1947	713
1948	640
1949	642
1950	789
1951	900
1952	818
1953	860
1954	1,090
1955	650
1956	777
1957	588
1958	654
1959	828
1960	774
1961	502
1962	680
1963	611
1964	537
1965	479
1966	667
1967	655
1968	709
1969	1,011
1970	695
1971	628
1972	824
1973	1,234
1974	855
1975	799
1976	1,011
1977	851
1978	709
1979	858
1980	513
1981	948
1982	670
1983	890
1984	905
1985	604
1986	772
1987	732
1988	597
1989	855
1990	1,103
1991	635
1992	683
1993	676
1994	666
1995	663
1996	1,188
1997	746
1998	894
1999	795
2000	788
2001	525
2002	614
2003	942
2004	654
2005	1,144
2006	1,012
2007	727
2008	1,134
2009	962
2010	871
2011	1,099
2012	808
2013	734
2014	851
2015	664
2016	624
2017	997
2018	904
2019	1,002
2020	735
2021	613
2022	734
2023	1,064
2024	747
2025	691

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	1904–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1904 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 Pemigewasset River and what each holds
Gauge	Measures	Values	Record
PEMIGEWASSET RIVER AT PLYMOUTH, NH	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	403	1903–2026
SMITH RIVER NEAR BRISTOL, NH	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	322	1918–2026
BAKER RIVER NEAR RUMNEY, NH	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	273	1927–2026

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 — 01070001. 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
PEMIGEWASSET RIVER AT PLYMOUTH, NH	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
SMITH RIVER NEAR BRISTOL, NH	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
BAKER RIVER NEAR RUMNEY, NH	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	3	yes, 3 or more
Years spanned	124	yes, 20 or more
Values held	998	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-01076500.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), Pemigewasset River gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-pemigewasset-river/

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 Pemigewasset River 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 confidence2024-12-12

Source: USGS — National Water Information System, USGS site 01076500, 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.