Gauge Catchment Area 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.

Sample rows

12 of 483,211 rows Taken from the start of observations-river-flow-usgs-nwis.csv. These are sample rows, not the dataset.

Sample rows from the Gauge Catchment Area 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`unit`	`period_start`	`period_end`	`period_kind`	`basis`	`confidence`	`source_id`	`source_ref`	`qualifier`	`superseded`	`retrieved`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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31
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	—	2026-08-31

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

Methodology

Read from the USGS station inventory, which publishes the area from its own basin delineation rather than from any measurement Hydrionis makes. Two areas are published and they are not the same quantity: the topographic drainage area is the land that drains to the gauge at the surface, and the contributing drainage area excludes the part that does not deliver water in an ordinary year — closed depressions, karst losing ground, land above a diversion. Where the publisher distinguishes the two, the contributing area is taken, because it is the denominator that makes a runoff depth mean what it says; which of the two a value reports is recorded on it. Square miles are converted to square kilometres and the publisher unit is recorded alongside.

What this dataset cannot tell you

Read before relying on these figures

The area is the publisher’s delineation, not a Hydrionis measurement, and different agencies delineate differently. Areas from different publishers should not be assumed to mean the same thing.
A catchment area is a statement with a date, and this one does not have the publisher’s. USGS states the area without saying when the basin was assessed, so the date on each value records when Hydrionis read it. A catchment is redrawn when a survey improves or a transfer scheme moves water between basins.
A contributing area and a topographic area can differ greatly on the same river. Dividing a discharge by the wrong one produces a runoff depth wrong by the ratio between them, which is why each value states which it is.
One station published an area larger than any United States basin and was refused rather than stored.

Coverage

Subjects	The United States Geological Survey streamgauges Hydrionis holds discharge for — 2,257 held
Period	2026–2026
Units	km²
Update cadence	Irregularly, when the publisher releases
Identifier	`gauge-catchment-areas` 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
`catchment-area`	Catchment area The land area draining to a gauging station, as the publisher of that station assesses it.	km²	river-gauge

Rights and access

Licence position

Open. 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

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.

Suggested citation for Hydrionis

Hydrionis (2026), Gauge Catchment Area Dataset, version 1.0.0, accessed 2026-09-02, hydrionis.com/data/datasets/gauge-catchment-areas/

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: Gauge Catchment Area 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.

None of the contributing licences requires attribution. Crediting the publishers is still good practice and they are listed above.

Changelog

Version 1.0.0 — 2026-08-31

First release: the denominator annual runoff was waiting for.

Additions

Catchment areas for 2,257 stations, each recording whether it is the topographic or the contributing area.

Use this data

Download river-flow observations from USGS (483,211 rows) (CSV)
Machine-readable JSON /api/v1/datasets/gauge-catchment-areas.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	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Mixed across the series — the basis is recorded on every individual value.
Period held	2026–2026
Known gaps	The area is the publisher’s delineation, not a Hydrionis measurement, and different agencies delineate differently. Areas from different publishers should not be assumed to mean the same thing. A catchment area is a statement with a date, and this one does not have the publisher’s. USGS states the area without saying when the basin was assessed, so the date on each value records when Hydrionis read it. A catchment is redrawn when a survey improves or a transfer scheme moves water between basins. A contributing area and a topographic area can differ greatly on the same river. Dividing a discharge by the wrong one produces a runoff depth wrong by the ratio between them, which is why each value states which it is.
Continuity	Version 1.0.0, released 2026-08-31. 1 recorded version; breaking changes and corrections are listed in the changelog above.
Last read from the publisher	2026-08-31 · 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