Hydrology Data Explorer API
Quality-controlled hydrometric measurement for England: daily mean river flow, river and groundwater level, and rainfall, from around 1,100 flow gauges and 3,600 observation boreholes. Several records begin in the nineteenth century — groundwater at Chilgrove House from 1836, flow on the Thames at Kingston from 1883 — making this one of the longest continuous instrumental water records available under an open licence anywhere.
Rights
- Licence
- Open Government Licence v3.0
- Commercial reuse
- Yes
- Redistribution
- Yes
- Derivative use
- Yes
- Attribution required
- YesContains public sector information licensed under the Open Government Licence v3.0.
- Terms last checked
- 24 August 2026
Access and coverage
- Publisher
- Environment Agency
- Geographic coverage
- England — gauging stations and observation boreholes
- Temporal coverage
- 1836 onwards
- Update frequency
- daily
- Formats
- json, csv, api, geojson, rdf
- Bulk download
- Available
- Registration required
- No
- Cost to Hydrionis
- Free
- Domains
- river flow, groundwater, precipitation, drought
Notes
The API serves the daily and sub-daily record; Hydrionis aggregates daily means to monthly and annual means as they are collected, because a monthly figure is the useful unit for the intelligence this platform publishes and holding tens of millions of daily readings statically would not be. The aggregation is recorded on every value: basis is "aggregated", not "measured", and the note states how many daily readings underlie each month. Readings carry the EA quality flag; Hydrionis keeps Good and Estimated readings and records which, and discards those flagged Missing, Suspect or Unchecked.
What Hydrionis holds from this publisher
The publisher’s own coverage is above. This is what Hydrionis has actually taken from it, at the subjects it measures — gauges, boreholes, reservoirs or places.
What is measured
- Groundwater level · m
- Mean monthly river flow · m³/s
- Mean river flow · m³/s
How current it is
- Current
- Read from EA 4 days ago, and the newest monthly value covers 2026-09 — as current as this source gets.
Hydrionis products built from it
Where this publisher’s data reaches a reader. Each has its own page, with its licence and how to cite it.