Warleggan River — monitoring and records

The monitoring network on this water

Hydrionis holds 926 values from 2 gauges on this water. Discharge is a property of a gauge and its reach, not of this water as a whole, so this page reports the network and its records rather than a single figure.

Gauges

926

Values held

1969–2026

Record spans

Gauges on the Warleggan River

2 monitoring points, positioned as the publisher records them.

The seasonal shape

An annual mean says how much water a river carried. A monthly record says when — and on most rivers the difference between a wet winter and a dry summer is larger than the difference between one year and the next.

Monthly mean flow at Warleggan River at Trengoffe

Each month's mean discharge as the publisher computed it, which shows the seasonal shape an annual mean flattens away. 1969–2026.

Show relevant events (4 events)Shading marks when something was recorded, not what caused the line.

Taken as the publisher computes it rather than recomputed by Hydrionis from daily values: the publisher knows which of its readings passed validation. Months the gauge did not cover are absent rather than interpolated, and the line breaks where they fall.

What the shaded periods are (4 events)

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
The 1976 drought	Drought declaration	1975-05-01 – 1976-08-31	Documented record	Compiled record
Yorkshire drought	Drought declaration	1995-04-01 – 1996-03-31	Documented record	Compiled record
The 2022 drought	Drought declaration	2022-03-01 – 2022-10-31	Documented record	Compiled record
European drought	Drought declaration	2022-05-01 – 2022-10-31	Documented record	Compiled record

Not shown on this chart

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.
Hurricane Katrina water and sanitation collapse — 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	Warleggan River at Trengoffe (m³/s)
1969	0.221
1970	2.24
1971	1.52
1972	1.55
1973	1.40
1974	2.60
1975	1.84
1976	0.749
1977	1.36
1978	1.39
1979	1.22
1980	1.30
1981	1.03
1982	1.37
1983	1.79
1984	1.82
1985	1.34
1986	1.93
1987	1.00
1988	2.20
1989	0.653
1990	1.60
1991	1.79
1992	0.548
1993	1.73
1994	2.49
1995	2.21
1996	2.38
1997	0.467
1998	2.19
1999	2.16
2000	1.46
2001	1.71
2002	1.24
2003	1.39
2004	1.58
2005	1.27
2006	0.811
2007	1.46
2008	1.19
2009	1.41
2010	1.37
2011	1.32
2012	1.47
2013	1.65
2014	2.89
2015	1.80
2016	2.79
2017	0.701
2018	2.04
2019	0.866
2020	1.36
2021	1.96
2022	1.17
2023	2.20
2024	1.62
2025	1.93
2026	2.50

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	Environment Agency — Hydrology Data Explorer API · Open Government Licence v3.0
How the values came to exist	Measured
Period held	1969–2026
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1969 to 2026 is held.
Last read from the publisher	2026-08-24
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 here

Gauges on the Warleggan River and what each holds
Gauge	Measures	Values	Record
Warleggan River at Trengoffe	mean river flow, mean monthly river flow	731	1969–2026
WARLEGGAN RIVER	ept family richness, life flow index (family level), proportion of sediment-sensitive invertebrates, whpt average score per taxon, whpt number of scoring taxa	195	1990–2025

How these gauges were attached to this water

Named by the publisher Each gauge here names this water in the publisher’s own station record. Hydrionis has not inferred the connection from station names.

What each gauge’s link to this water rests on
Gauge	Evidence	Established
Warleggan River at Trengoffe	Stated by the publisher — Environment Agency hydrology station register, riverName field — https://environment.data.gov.uk/hydrology/id/stations	2026-08-26
WARLEGGAN RIVER	Stated by the publisher on the record this gauge’s observations came from.	With the observations

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 3 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	58	yes, 20 or more
Values held	926	no
Distinct measurements	7	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-ea-f87436ec-9077-49de-85c0-bf935ee0e3f8.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

Attribution you are required to give

These are conditions of the licences the underlying data is published under. They are obligations to the publishers, not to Hydrionis, and they apply to you directly whether or not you mention Hydrionis at all.

Contains public sector information licensed under the Open Government Licence v3.0.

Environment Agency — Open Government Licence v3.0 (licence text)

Suggested citation for Hydrionis

Hydrionis (2026), Warleggan River gauge records, accessed 2026-09-02, hydrionis.com/waters/england-warleggan-river/

Cite Hydrionis where you rely on the compilation, the normalisation, the eligibility judgements or a chart. Where you use an unmodified published value, the publisher’s attribution is the one that is required; crediting Hydrionis as well is welcome and is not something Hydrionis can require of you.

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 Warleggan 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.

Where these figures come from

Spatially aggregatedHigh confidence2024

Source: EA — Hydrology Data Explorer API, EA measure f87436ec-9077-49de-85c0-bf935ee0e3f8-flow-m-86400-m3s-qualified. Licence: Open — attribution required (attribution required).

Method: Mean of the twelve monthly means for the year. Computed from months rather than from daily readings directly, so that a year with uneven observation is not weighted toward its best-observed months. Years with any month missing are not published.

Aggregated by Hydrionis from daily mean flow published by the Environment Agency under the Open Government Licence v3.0.

Retrieved 24 August 2026.