PUBLIC ATLAS · Checklist edition 29 September 2026
The right place
Match the station ID, county, locality or reservoir—not just a similar name. A nearby station may be a reference for an area without measuring that exact location.
See the tide-station example →The right measurement
Read the unit and reference level. Feet of river stage and feet of reservoir elevation describe different things. A percentage needs a defined denominator.
Understand gauge readings →The right date
Separate when a value was observed, when it was retrieved and when the explanation was reviewed. A successful download does not make an old reading current.
Check our source status →The issuing source
Follow the agency or operator link and compare the record. Keep its identifier, source time and any provisional or revised status with your notes.
Open the source register →The limits of the answer
A mapped area is not a test of an individual home; a station record is not a property inspection. Read the source-specific limits before using the answer.
See the radon example →
Keep this with your note
Source URL · place/station ID · measure and unit · observed/effective time · retrieved time · method or revision · limitations.
If one of these is missing, describe the uncertainty instead of filling the gap with an assumption.
For the methods used here, see our source and methodology notes. To report an error, see corrections.
Public Atlas Editorial · Published 2026-09-29 · Updated 2026-09-29. Independent human review pending. Next scheduled review: 2026-10-29. AI-assisted resource.
The short answer
Before using a number, check its place, measure, applicable date, issuing source and limitations. Keep those details with your notes so someone else can reproduce the lookup.
Common questions
Which date should I write beside a reading?
Keep its observation date and retrieval time separately. A newer retrieval can contain the same older observation.
What should I send when reporting a mismatch?
Include the page URL, station or place, measurement, both dates, displayed value and official source URL.