London and Water · Data sources

Where the readings come from.

The map combines regularly collected Environment Agency data with retained historical water-research collections. Each keeps its own units, dates, methods, source identifiers and qualifications.

Previous service’s operating history remains available as a read-only record. Current collection uses the schedules below.

Regularly collected feeds

Daily collection is scheduled for 10:00 UTC. These are collection schedules, not a guarantee that the publisher has released every recent observation. Outages, retries and long collection passes can delay the next update. Recent overlaps can incorporate newly published or revised results, but do not establish that all historical revisions have been discovered.

The server prepares a shared browsing view from committed imports, normally checking once a minute. The API reference explains how separate requests can see successive completed publications.

Water Quality Explorer attribution: © Environment Agency copyright and/or database right 2025. All rights reserved. Contains public sector information licensed under the Open Government Licence v3.0. Source-specific statements and original metadata remain attached to the records.

The nine observed tide gauges

The input selection is London’s 50 km circle plus these explicitly named stations. Southend and Sheerness are retained outside the circle; their inclusion does not add surrounding stations or widen other feeds.

• Teddington Lock Tail — 3401TH_TAOD
• Richmond — 0009
• Westminster — 0006
• Tower Pier — 0007
• Charlton — 0003
• Silvertown — 0001
• Tilbury — 0020
• Southend — 0019
• Sheerness — E71539

These readings use the source’s mAOD unit and AOD datum. The source identifies Sheerness as a mean series and the other eight as instantaneous series; those distinctions are retained. They are observed levels, not TideCheck or other predicted tides, and must not be silently compared with heights on a different datum.

Retained water-research collections

These are acquired research editions, not continuously refreshed feeds. The map offers their located graphable measurements. Source records also retain missing values, supporting fields and nonpoint context; preserving those records does not create an invented map position or measurement.

UKCEH Thames Initiative

Weekly water-quality data from the River Thames and its major tributaries, 2009–2023. The retained feeds are thames-initiative and thames-location-review; the latter name records a historical location review rather than a different measurement programme.

Bowes, M.J.; Armstrong, L.K.; Nicholls, D.J.E.; Williams, M.; O’Brien, A.; Duenas-Lopez, M.A.; Duke, E.; Juergens, M.D. (2025). Weekly water quality data from the River Thames and its major tributaries, 2009–2023. Contains data supplied by UK Centre for Ecology & Hydrology. © UK Centre for Ecology & Hydrology. OGL v3.0.

Historic UK Harmonised Monitoring Scheme

The London selection comes from the 1974–2013 UK HMS archive (hms). A separate retained group, hms-unplaced-national-reference, has no resolved station dictionary entry. It is not given an invented location or offered as a mapped measurement.

Historic UK Harmonised Monitoring Scheme. Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. All rights reserved © Environment Agency © Scottish Environmental Protection Agency © Northern Ireland Agri-Food and Biosciences Institute. OGL v3.0.

EA GC-MS and LC-MS screening

The ea-gcms and ea-lcms feeds retain a chemical-screening snapshot extracted in August 2024, covering reported results from 2007–2024. This is a semi-quantitative screening collection, not a record of every chemical tested or a complete absence/presence survey. Concentrations, detection limits and analytical scores remain separate supporting fields; a missing score does not invalidate a present concentration.

EA water-quality monitoring: GC-MS and LC-MS semi-quantitative screen. © Environment Agency copyright and/or database right 2015. All rights reserved. OGL v3.0.

River Thames Historical Water Quality Data

The University of Bristol collection covers 1868–2020. The bristol-unlocated feed retains historical chemistry and flow with their recovered station context; its old feed name is not the current geographic status. bristol-catchment-reference retains catchment context, including population and phosphorus-input estimates. Reconstructed temperatures and period averages retain their source descriptions and must not be read as individual instrument samples.

Howden, N.; Burt, T.P.; Worrall, F.; Jarvie, H.P. (2024). River Thames Historical Water Quality Data. University of Bristol. Contains information licensed under the Non-Commercial Government Licence v2.0. These terms restrict commercial reuse.

Caravan-Qual

The retained London subset of Caravan-Qual v1.1 comprises caravan-assessment chemistry and caravan-linked-flow-assessment flow attachments. It is a compiled and processed research dataset; imputation methods, detection limits, flags and linked-gauge identities remain attached. Repeated source flow attachments are not presented as proof of independent flow observations.

Jones, E.; Kratzert, F.; van Vliet, M.T.H. (2026). Caravan-Qual (lite): A global scale integration of water quality observations into a large sample hydrology dataset, v1.1. The compilation is published under CC BY 4.0; its constituent source notices also apply. UK-EA’s component notice specifies OGL v3.0. CAMELS-GB’s component notice specifies OGL v3.0 and credits data supplied by Natural Environment Research Council.

CAMELS-GB: Coxon, G.; Addor, N.; Bloomfield, J.P.; Freer, J.; Fry, M.; Hannaford, J.; Howden, N.J.K.; Lane, R.; Lewis, M.; Robinson, E.L.; Wagener, T.; Woods, R. (2020). Catchment attributes and hydro-meteorological timeseries for 671 catchments across Great Britain. NERC Environmental Information Data Centre.

The distributed Caravan-Qual CSV rows do not identify the original contributing database per row. A UK station location alone does not establish the applicable component licence. Consult the publisher’s source and licence documentation when reusing this compilation; no blanket OGL claim is made for all its rows.

Understanding coverage and source detail

Each collection has its own scope. The same chemical can have separate units, materials, methods, periods or result roles. The picker groups related definitions for navigation without making them scientifically interchangeable. Original missing states and source qualifications remain visible in the record’s Details form.

This register describes the current water map. It is not the old server’s operating-control register or a list of every dataset ever acquired. The existing account area remains separate. Basemap and font credits describe the geographic background independently of these measurements.