River Levels Application Programming Interface (API)

This dataset covers monitoring data that is updated on our systems on a minimum of a daily update cycle. This is increased during times of flooding etc. Measurements of the height (m) of water in a river, lake or coastal site taken using automatic field devices, are given usually every 15 minutes. Information is available for NRW river monitoring sites throughout Wales, as well as some reservoirs and coastal sites.

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What's in it

Data offered docs-verified: river water level (height, m) · lake water level (height, m) · coastal water level (height, m) · reservoir levels (some sites)
Coverage docs-verified: Wales: NRW river monitoring sites, plus some reservoirs and coastal sites
Resolution docs-verified: Temporal: usually every 15 minutes; spatial: individual monitoring sites (point measurements)
Update frequency docs-verified: Minimum daily update cycle, increased during flooding; dataset metadata lists frequency as continual
Formats docs-verified: Download · Web Service
Access docs-verified: Free and open; no access restrictions and no authentication (ENTRY auth is null). Licence: Open Government Licence v3.0 per site footer (metadata licence field reads 'Not set')

Useful for

Use cases llm-inferred: Flood risk assessment: observed river stage at the nearest Welsh NRW gauge as baseline context · Flood event review and hydraulic model calibration or validation against recorded water levels · Coastal or tidal level context for outfall or drainage assessments near NRW coastal sites
Audience llm-inferred: flood consultants · hydrologists · drainage engineers · GIS analysts

Limitations

Constraints llm-inferred: Wales only · Water height (m) only; flow would need a stage-discharge rating, which the docs do not describe · Updates are at least daily and not guaranteed real-time · Reservoir and coastal coverage is partial · API endpoints, parameters and response schema are not documented in the supplied DOCS · Dataset metadata shows Licence as 'Not set' despite the OGL footer

Licence: ["There are no access restrictions on this data. NRW may release, publish or disseminate it freely.", "\u00a9 CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is
Authentication: Unknown — review source docs
GitHub stars: Unknown
Last commit: Unknown
Last successful page check: 16/10/2026
Page health: page reachable
Package: Not recorded
Verification: Not independently verified

Provenance & evidence

Listed in data.gov.uk public catalogue API on 2026-10-16; relevance/value screened (haiku).

Metadata observed 14/10/2026 · research sweep: sweep-2026-10-16 (data.gov.uk)