Annual Runoff Depth 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 Annual Runoff Depth 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`unit`	`period_start`	`period_end`	`period_kind`	`basis`	`confidence`	`source_id`	`source_ref`	`qualifier`	`superseded`	`retrieved`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

Each value is the year’s mean discharge multiplied by the seconds in that year and divided by the area draining to the gauge, giving the depth that volume of water would make over that area. Leap years are counted. The discharge is the publisher’s own annual mean and the area is the publisher’s own delineation — the contributing area where one is distinguished, the topographic area otherwise — and every value records which was used. Produced only where a gauge holds at least five years of annual mean discharge and an area is held for it; a gauge whose publisher states no drainage area produces nothing rather than a figure divided by a guess.

What this dataset cannot tell you

Read before relying on these figures

This is not a water balance. Runoff is what left the catchment past the gauge, and the difference between the rain that fell and the runoff that emerged is not evaporation alone — it includes change in groundwater storage, water abstracted and taken elsewhere, and water imported by a transfer scheme. A catchment yielding more runoff than its rainfall is usually being fed from outside rather than measured wrongly.
Every value rests on the catchment area beneath it, which Hydrionis does not measure. A revised area, or a topographic area used where a contributing one was meant, rescales an entire series by the ratio between them.
A runoff depth is an average over a whole year and over the whole catchment. It says nothing about where within the catchment the water came from, or when within the year.
Comparing runoff with rainfall requires rainfall for the same catchment. A station total from a gauge that happens to be nearby is a point measurement and is not catchment rainfall.

Coverage

Subjects	United States gauging stations for which both an annual mean flow and a catchment area are held — 1,687 held
Period	1874–2025
Units	mm
Update cadence	Irregularly, when the publisher releases
Identifier	`annual-runoff-depth` 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
`runoff-annual`	Annual runoff The depth of precipitation that becomes river flow rather than evaporating or being stored, over a year.	mm	catchment, grid-cell

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), Annual Runoff Depth Dataset, version 1.0.0, accessed 2026-09-02, hydrionis.com/data/datasets/annual-runoff-depth/

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: Annual Runoff Depth 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, made possible by collecting the catchment areas.

Method version: discharge-to-runoff-depth 1.0.0

Additions

Annual runoff depth for every gauge holding both a long enough flow record and a published catchment area.

Use this data

Download river-flow observations from USGS (483,211 rows) (CSV)
Machine-readable JSON /api/v1/datasets/annual-runoff-depth.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	Derived Computed by Hydrionis
Period held	1874–2025
Known gaps	This is not a water balance. Runoff is what left the catchment past the gauge, and the difference between the rain that fell and the runoff that emerged is not evaporation alone — it includes change in groundwater storage, water abstracted and taken elsewhere, and water imported by a transfer scheme. A catchment yielding more runoff than its rainfall is usually being fed from outside rather than measured wrongly. Every value rests on the catchment area beneath it, which Hydrionis does not measure. A revised area, or a topographic area used where a contributing one was meant, rescales an entire series by the ratio between them. A runoff depth is an average over a whole year and over the whole catchment. It says nothing about where within the catchment the water came from, or when within the year.
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	not recorded · 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