Reading a river level
What the number means, where it comes from, and why the station matters.
Start with the station
A water-level reading describes the height of the water at one instrument, at one time. Always read the station name and observation time alongside the number. A station does not describe every stretch of its river.
Metres above a local reference
OPW sensor 0001 reports water level in metres. The number is measured relative to a reference level, or datum, at the station. It is not the depth of the water. Two stations can have different reference levels, so their readings cannot be compared directly.
Read the shape, then the gaps
The chart shows published observations over the period you select. Missing intervals are left open rather than filled with invented values. A rising series describes what the instrument recorded; it does not predict what happens next.
Check the time
Times are displayed in Ireland’s local time, including the change between winter and summer time. A reading more than one hour old is marked as an older observation. Publication and collection can introduce delays.
A level is not a safety decision
Water level alone cannot tell you about currents, debris, bank access, pollution or conditions upstream. This atlas does not make swimming or paddling judgements and does not issue flood forecasts. Consult official information and appropriate local advice.