Hydrionis Data

River Macroinvertebrate Community Dataset

Four community indices from the Environment Agency’s standardised freshwater invertebrate sampling in England, at the 2,611 river sites with a record long enough to show change — at least thirty samples across at least fifteen years, from 1965. WHPT scores the community for organic pollution, LIFE for flow, PSI for fine sediment, and the taxon count for richness. The animals in a riverbed cannot leave, so what persists at a site integrates everything the river did between visits, including the pollution incident nobody sampled and the drought that ended before anyone arrived.

v1.0.0470,453 observations1965–2026

470,453

Observations

10,444

Series

2,611

Subjects

1965–2026

Period covered

What this looks like

One real series from the dataset, and real rows from the head of its published extract. Neither is a mock-up: the rows below are the same rows, unchanged, that are in the file you would download.

WHPT average score per taxon at CRANLEIGH WATERS

The longest single series this dataset holds — 137 daily values, one of 10,444. The dataset is not this chart.

Drawn to show the shape and resolution of what the dataset contains, not to make a point about CRANLEIGH WATERS. Gaps are breaks, never interpolated.

View the data behind this chart

Underlying data
Period	CRANLEIGH WATERS (index)
1990	3.63
1991	3.50
1992	4.57
1994	4.05
1995	4.59
1996	3.52
1997	3.61
1998	4.30
1999	4.17
2000	4.58
2001	4.49
2002	3.94
2003	4.47
2004	4.11
2005	4.37
2006	5.29
2007	5.18
2008	4.53
2009	5.51
2010	3.71
2011	4.23
2012	4.28
2013	5.29
2014	5.93
2015	5.26
2016	5.27
2017	4.83
2018	4.80
2019	3.75
2020	3.86
2021	5.86
2022	5.77
2023	4.82
2024	5.14

Sample rows

12 of 637,594 rows Taken from the start of observations-ecosystem-uk-ea-ecology.csv. These are sample rows, not the dataset.

Sample rows from the River Macroinvertebrate Community Dataset extract
`metric_id`	`subject_id`	`subject_kind`	`value`	`censored`	`censor_operator`	`censor_threshold`	`censor_limit`	`censor_reported`	`unit`	`period_start`	`period_end`	`period_kind`	`basis`	`confidence`	`source_id`	`source_ref`	`qualifier`	`superseded`	`retrieved`
ept-family-richness	eco-ea-1000	geography	8	—	—	—	—	—	count	1991-07-29	1991-07-29	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	9	—	—	—	—	—	count	1995-03-22	1995-03-22	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	6	—	—	—	—	—	count	1995-10-17	1995-10-17	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	7	—	—	—	—	—	count	1996-04-03	1996-04-03	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	10	—	—	—	—	—	count	1996-06-27	1996-06-27	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	8	—	—	—	—	—	count	1996-10-10	1996-10-10	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	3	—	—	—	—	—	count	1997-03-12	1997-03-12	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	8	—	—	—	—	—	count	1997-07-14	1997-07-14	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	11	—	—	—	—	—	count	1997-09-30	1997-09-30	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	7	—	—	—	—	—	count	1998-04-21	1998-04-21	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	8	—	—	—	—	—	count	1998-07-28	1998-07-28	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28
ept-family-richness	eco-ea-1000	geography	11	—	—	—	—	—	count	1998-09-30	1998-09-30	day	calculated	high	uk-ea-ecology	INV_OPEN_DATA_TAXA.csv	—	—	2026-08-28

Download these rows as CSV — the same twelve, with the column header, for testing a loader before committing to the full file.

Methodology

Collected from the Agency’s Ecology and Fish Data Explorer bulk download. Indices are taken as the Agency computes and publishes them rather than recomputed. Sites are published as British National Grid eastings and northings with no latitude or longitude, and are converted by inverting the transverse Mercator projection of the Airy 1830 ellipsoid and then applying a Helmert datum shift to WGS84; omitting the second step would leave every site about a hundred metres out. Where a sample was reanalysed the latest version is held; field replicates sharing a site, date and version are dropped rather than averaged, because their mean is a statistic the Agency never published. Sites whose grid reference falls outside the National Grid are not held rather than placed approximately.

What this dataset cannot tell you

Read before relying on these figures

An index is not a count. It scores which taxa were present against a table of sensitivities, so two samples with identical indices can differ tenfold in the number of animals, and a rising index is a community shifting towards sensitive taxa rather than a population recovering.
Strongly seasonal. The Agency samples in spring and autumn and the communities differ substantially between them, so a year-on-year comparison that mixes seasons will find changes that are the calendar rather than the river. Each observation carries its own sample date so the two can be separated.
Not comparable with biological indices from other countries. WHPT, LIFE and PSI are British indices built on British taxon tables and a British sampling protocol, and a European or American index with a similar range does not mean the same thing.
Sites with short records are excluded, not missing. Of 30,693 sites the median has three samples; the 2,611 held are those with at least thirty samples across at least fifteen years. Any national picture drawn from this describes long-monitored sites, which the Agency chose for reasons — often known pressures — and which are not a random sample of English rivers.
Describes the sampled reach and not the river. Conditions can differ sharply above and below a discharge, a weir or a confluence.
NTAXA is sensitive to analytical effort and to the taxonomic level the analyst worked at, so a change in laboratory practice can move it without the river changing.
The full taxon lists are not held. Anyone needing which species were present, rather than what the community indicates, needs the publisher’s taxon archive.

Coverage

Subjects	Environment Agency river macroinvertebrate monitoring sites in England with a long record — 2,611 held
Period	1965–2026
Units	%, count, index
Update cadence	Irregularly, when the publisher releases
Identifier	`river-macroinvertebrates` v1.0.0

Fields

Data dictionary →

Every metric this dataset carries, with the unit it is stored in and the geography level it is reported at. Full definitions are in the data dictionary.

Identifier	Field	Unit	Reported at
`whpt-aspt`	WHPT average score per taxon Mean pollution-sensitivity score of the scoring macroinvertebrate taxa found in a standardised sample, under the Walley Hawkes Paisley Trigg system.	index	monitoring-station
`whpt-ntaxa`	WHPT number of scoring taxa Count of macroinvertebrate taxa in a standardised sample that carry a WHPT sensitivity score.	count	monitoring-station
`life-family-index`	LIFE flow index (family level) Lotic-invertebrate Index for Flow Evaluation: mean flow-preference score of the macroinvertebrate families found in a standardised sample.	index	monitoring-station
`psi-family-score`	Proportion of sediment-sensitive invertebrates Share of the macroinvertebrate community made up of families sensitive to fine sediment, on a scale of 0 to 100.	%	monitoring-station

Rights and access

Licence position

Open with attribution. Derivative use true; redistribution true; commercial reuse true.

Permitted uses

Public display
Derived analysis
API delivery
Bulk download
Commercial use

Available to: Public, Developer, Research, Professional, Enterprise. These follow from the rights of the contributing publishers, not from a Hydrionis pricing decision — no access tier can widen what a publisher withheld.

Contributing sources

Environment Agency — Ecology and Fish Data Explorer — freshwater macroinvertebrates (Open Government Licence v3.0)

Attribution and citation

Cite and reuse →

Two different obligations, deliberately kept apart. One is a condition of somebody else's licence; the other is a request Hydrionis has no standing to enforce.

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), River Macroinvertebrate Community Dataset, version 1.0.0, accessed 2026-09-02, hydrionis.com/data/datasets/river-macroinvertebrates/

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: River Macroinvertebrate Community Dataset 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.

Changelog

Version 1.0.0 — 2026-08-27

First release.

Additions

WHPT ASPT, WHPT NTAXA, LIFE and PSI at 2,611 long-record English river sites, from 1965.

Use this data

Download ecosystem observations from EA ecology (637,594 rows) (CSV)
Machine-readable JSON /api/v1/datasets/river-macroinvertebrates.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

Every bulk extract ships with a companion metadata file carrying this dataset’s version, its sources, their licences, the attribution you are required to give and the suggested citation — so the terms travel with the file rather than staying on this page.

About this data

The fields a professional user needs to judge whether this is fit for a particular purpose. Deliberately not a score.

About this data

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 — Ecology and Fish Data Explorer — freshwater macroinvertebrates · Open Government Licence v3.0
How the values came to exist	Mixed across the series — the basis is recorded on every individual value.
Period held	1965–2026
Known gaps	An index is not a count. It scores which taxa were present against a table of sensitivities, so two samples with identical indices can differ tenfold in the number of animals, and a rising index is a community shifting towards sensitive taxa rather than a population recovering. Strongly seasonal. The Agency samples in spring and autumn and the communities differ substantially between them, so a year-on-year comparison that mixes seasons will find changes that are the calendar rather than the river. Each observation carries its own sample date so the two can be separated. Not comparable with biological indices from other countries. WHPT, LIFE and PSI are British indices built on British taxon tables and a British sampling protocol, and a European or American index with a similar range does not mean the same thing.
Continuity	Version 1.0.0, released 2026-08-27. 1 recorded version; breaking changes and corrections are listed in the changelog above.
Last read from the publisher	2026-08-27 · publisher updates irregularly, when the publisher releases
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