The monitoring network within this area

Hydrionis holds 941 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

941

Values held

1919–2026

Record spans

Gauges within the Outlet Connecticut 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 HOCKANUM RIVER NEAR EAST HARTFORD, CT

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1920–2025.

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	HOCKANUM RIVER NEAR EAST HARTFORD, CT (m³/s)
1920	52.7
1929	33.7
1930	11.0
1931	11.5
1932	12.3
1933	14.5
1934	54.4
1935	22.9
1936	51.3
1938	146
1939	37.9
1940	39.9
1941	47.9
1942	18.0
1944	28.9
1945	27.2
1947	10.4
1948	24.9
1950	19.8
1951	28.3
1952	26.6
1953	32.6
1954	32.6
1955	77.6
1957	12.9
1958	15.9
1959	36.0
1960	35.1
1961	25.8
1962	40.2
1963	28.3
1964	17.8
1965	20.0
1966	14.2
1967	23.0
1968	20.8
1969	24.9
1970	57.2
1971	12.6
1972	32.6
1973	51.0
1975	49.0
1976	54.1
1977	35.1
1978	65.7
1979	96.3
1980	49.3
1981	20.5
1982	75.9
1983	56.4
1984	58.6
1985	21.7
1986	23.7
1987	36.0
1988	13.7
1989	27.5
1991	43.0
1992	23.4
1993	23.2
1994	32.3
1995	18.4
1996	57.5
1998	39.6
1999	36.5
2000	39.4
2001	33.4
2002	18.0
2004	36.8
2005	27.6
2007	45.9
2008	44.7
2010	50.4
2011	63.7
2013	45.6
2014	41.1
2016	34.8
2017	34.0
2019	52.1
2021	90.3
2022	29.7
2023	47.6
2025	27.3

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	1920–2025
Completeness	77.4% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	17 separate periods inside 1920–2025 hold no value. The longest runs from 1921 to 1928 — 8 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1920 and is not continuous from it: 106 years separate the first value from the last, and 77% 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 CONNECTICUT RIVER AT THOMPSONVILLE, CT, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1929–2025.

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	CONNECTICUT RIVER AT THOMPSONVILLE, CT (mm)
1929	568
1930	437
1931	467
1932	545
1933	588
1934	585
1935	546
1936	715
1937	712
1938	756
1939	550
1940	578
1941	346
1942	525
1943	644
1944	475
1945	752
1946	522
1947	602
1948	524
1949	459
1950	539
1951	684
1952	661
1953	661
1954	746
1955	707
1956	598
1957	449
1958	605
1959	618
1960	667
1961	508
1962	510
1963	438
1964	425
1965	315
1966	422
1967	524
1968	529
1969	708
1970	552
1971	476
1972	708
1973	823
1974	657
1975	695
1976	809
1977	713
1978	556
1979	771
1980	455
1981	595
1982	561
1983	784
1984	748
1985	450
1986	666
1987	638
1988	511
1989	677
1990	855
1991	622
1992	545
1993	614
1994	642
1995	516
1996	929
1997	613
1998	673
1999	557
2000	700
2001	495
2002	537
2003	748
2004	562
2005	828
2006	841
2007	631
2008	914
2009	747
2010	689
2011	963
2012	499
2013	640
2014	696
2015	540
2016	473
2017	663
2018	783
2019	742
2020	555
2021	633
2022	533
2023	880
2024	658
2025	543

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	1929–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1929 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 Outlet Connecticut River and what each holds
Gauge	Measures	Values	Record
SALMON RIVER NEAR EAST HAMPTON, CT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	328	1928–2026
CONNECTICUT RIVER AT THOMPSONVILLE, CT	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	327	1928–2026
HOCKANUM RIVER NEAR EAST HARTFORD, CT	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	286	1919–2026

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 — 01080205. 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
SALMON RIVER NEAR EAST HAMPTON, CT	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
CONNECTICUT RIVER AT THOMPSONVILLE, CT	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
HOCKANUM RIVER NEAR EAST HARTFORD, CT	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	108	yes, 20 or more
Values held	941	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-01193500.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), Outlet Connecticut River gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-outlet-connecticut-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 Outlet Connecticut 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 confidence2025-05-09

Source: USGS — National Water Information System, USGS site 01193500, 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.