Hydrionis Gauge–Water Linkage Dataset

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.

Mean river flow at Muroleenkoski

The longest single series this dataset holds — 59,808 daily values, one of 2,086. Drawn from 600 of them, evenly spaced across the record. The dataset is not this chart.

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

View the data behind this chart

Underlying data
Period	Muroleenkoski (m³/s)
1863	25.0
1864	56.0
1865	15.5
1866	29.0
1867	35.0
1868	14.0
1869	16.9
1870	46.0
1871	17.1
1872	23.0
1873	61.0
1874	20.0
1875	48.0
1876	3.90
1877	13.1
1878	93.0
1879	61.0
1880	11.0
1881	12.0
1882	37.0
1883	12.0
1884	74.0
1885	8.30
1886	17.1
1887	27.0
1888	19.8
1889	12.9
1890	37.0
1891	25.0
1892	11.5
1893	29.0
1894	31.0
1895	16.9
1896	26.0
1897	21.0
1898	46.0
1899	65.0
1900	33.0
1901	26.0
1902	21.0
1903	30.0
1904	70.0
1905	29.0
1906	34.0
1907	24.0
1908	27.0
1909	1.95
1910	47.0
1911	22.0
1912	32.0
1913	72.0
1914	22.0
1915	17.1
1916	35.0
1917	40.0
1918	40.0
1919	59.0
1920	24.0
1921	22.0
1922	27.0
1923	39.0
1924	35.0
1925	60.0
1926	16.9
1927	18.0
1928	40.0
1929	40.0
1930	57.0
1931	48.0
1932	43.0
1933	33.0
1934	14.0
1935	58.0
1936	39.0
1937	39.0
1938	28.0
1939	24.0
1940	19.0
1941	20.0
1942	5.00
1943	42.0
1944	57.0
1945	76.0
1946	24.0
1947	33.0
1948	11.0
1949	41.0
1950	15.0
1951	59.0
1952	34.0
1953	19.8
1954	47.0
1955	66.0
1956	39.0
1957	40.0
1958	53.0
1959	26.0
1960	26.0
1961	43.0
1962	40.0
1963	53.0
1964	34.0
1965	41.0
1966	34.0
1967	46.0
1968	38.0
1969	38.0
1970	24.0
1971	40.0
1972	33.0
1973	40.0
1974	45.0
1975	135
1976	24.0
1977	30.0
1978	47.0
1979	28.0
1980	83.0
1981	46.0
1982	45.0
1983	88.0
1984	45.0
1985	32.0
1986	49.0
1987	60.0
1988	48.0
1989	46.0
1990	48.0
1991	26.0
1992	76.0
1993	66.0
1994	25.0
1995	49.0
1996	21.0
1997	53.0
1998	40.0
1999	41.0
2000	47.0
2001	88.0
2002	47.0
2003	11.5
2004	39.0
2005	66.0
2006	26.0
2007	94.0
2008	82.0
2009	44.0
2010	18.5
2011	24.0
2012	57.0
2013	53.0
2014	50.0
2015	71.0
2016	59.0
2017	31.0
2018	44.6
2019	13.3
2020	118
2021	63.7
2022	33.0
2023	46.9
2024	65.0
2025	62.9
2026	33.0

Sample rows

12 of 646,106 rows Taken from the start of observations-river-flow-usgs-nwis.csv. These are sample rows, not the dataset.

Sample rows from the Hydrionis Gauge–Water Linkage 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`
catchment-area	gauge-usgs-01010500	geography	6980.017957	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01010500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01011000	geography	3180.505399	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01011000, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01013500	geography	2253.289656	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01013500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01014000	geography	14700.772514	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01014000, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01018500	geography	1061.895125	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01018500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01019000	geography	580.157337	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01019000, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01020000	geography	3405.834365	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01020000, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01021500	geography	1186.214555	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01021500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01023000	geography	383.31824	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01023000, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01029500	geography	2812.727088	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01029500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01031500	geography	766.636481	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01031500, contributing drainage area	contributing area	—	2026-10-01
catchment-area	gauge-usgs-01033000	geography	841.746136	—	—	—	—	—	km²	2026-08-31	—	instant	reported	high	usgs-nwis	USGS site 01033000, contributing drainage area	contributing area	—	2026-10-01

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

Methodology

A governed derivation, worked out once and stored rather than recalculated when a page is shown, so river pages render without contacting the publishers. Four station registers are read: the Environment Agency’s riverName, SEPA’s river_name and catchment_name, Hub’Eau’s libelle_cours_eau with the Sandre watercourse code, and the USGS site service’s huc_cd, named from the Watershed Boundary Dataset. All four are Tier A — the publisher’s own statement about its own station. Two further jurisdictions state the water body on the record Hydrionis already reads, and those relationships arrive with the observations rather than through this derivation; the registry records which route each took and ranks neither above the other. There is deliberately no name-matching tier.

What this dataset cannot tell you

Read before relying on these figures

A United States linkage attaches a gauge to an eight-digit hydrologic subbasin, which is a drainage area and not a river. Many subbasins take the name of the largest river within them, and a gauge in one may sit on any watercourse inside it.
Nine hundred and nine river gauges remain unresolved, and are reported as unresolved rather than inferred. Most are Irish and Dutch: the Office of Public Works publishes the relationship behind a click-through agreement granting no reuse licence, and Rijkswaterstaat publishes no water body at all.
Boreholes, raingauges and water quality sampling points are not linked to water bodies and are not counted as unresolved. A borehole measures an aquifer and a raingauge measures the sky.
A publisher renaming a river changes this dataset. Because it is stored and versioned rather than recalculated each time, such a change appears as a reviewable difference rather than as a page that quietly says something new.
No spatial tier exists. One was prototyped against an authoritative open river-water-body layer and not shipped, because the coordinate handling could not be validated to a standard that would justify publishing a river name.

Coverage

Subjects	River gauges in jurisdictions whose publisher states the water body — 2,086 held
Period	1880–2010
Units	m³/s
Update cadence	Irregularly, when the publisher releases
Identifier	`gauge-water-linkage` 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
`river-flow-mean`	Mean river flow Average volumetric discharge past a gauging station over a stated period.	m³/s	river-gauge
`river-level`	River level Height of the water surface at a gauging station, measured against that station’s own zero point.	m	river-gauge

Rights and access

Licence position

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

Applies to material authored by US federal agencies. Third-party material carried within a federal product may be separately protected.

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 — Hydrology Data Explorer API (Open Government Licence v3.0)
United States Geological Survey — National Water Information System (US Government work — public domain)

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), Hydrionis Gauge–Water Linkage Dataset, version 1.0.0, accessed 2026-10-05, hydrionis.com/data/datasets/gauge-water-linkage/

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: Hydrionis Gauge–Water Linkage 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 — 2026-08-26

First release. Unresolved river gauges fall from 4,166 to 909 without a single name match.

Additions

Tier A linkage for England, Scotland, France and the United States, from four publisher station registers.
Method, method version, evidence source and derivation date recorded on every relationship.
Canonical water-body types derived from evidence, keeping a United States hydrologic unit distinct from a river.

Use this data

Download river-flow observations from USGS (646,106 rows) (CSV)
Download river-flow observations from EA (261,070 rows) (CSV)
Machine-readable JSON /api/v1/datasets/gauge-water-linkage.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 — Hydrology Data Explorer API · Open Government Licence v3.0 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	1880–2010
Known gaps	A United States linkage attaches a gauge to an eight-digit hydrologic subbasin, which is a drainage area and not a river. Many subbasins take the name of the largest river within them, and a gauge in one may sit on any watercourse inside it. Nine hundred and nine river gauges remain unresolved, and are reported as unresolved rather than inferred. Most are Irish and Dutch: the Office of Public Works publishes the relationship behind a click-through agreement granting no reuse licence, and Rijkswaterstaat publishes no water body at all. Boreholes, raingauges and water quality sampling points are not linked to water bodies and are not counted as unresolved. A borehole measures an aquifer and a raingauge measures the sky.
Continuity	Version 1.0.0, released 2026-08-26. 1 recorded version; breaking changes and corrections are listed in the changelog above.
Inputs last read	2026-10-01 · when the records this was computed from were last read from their publishers · 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