Understanding River Level Alerts in QLD

When you open Queensland river data, you’ll usually see a table like the one shown (station name, time, height, trend, flood level, plot links). Here’s what it actually means, how reliable it is, and how to tell if it’s working.

What a river alert is

Each line is a physical monitoring station installed at a bridge, creek crossing, weir, dam or river reach.

It automatically measures water level and sends the data back to the network every few minutes.

What’s in the station

• Water level sensor (radar above water or pressure sensor in water)

• Small computer (data logger)

• Communications (mobile, radio or satellite)

• Power supply (often solar + battery, sometimes mains in towns)

What the table columns mean

• Station Name – Where the gauge physically sits

• Time/Day – When the last reading was received

• Height (m) – Current water level relative to that site’s gauge reference

• Gauge Datum (LGH/AHD) – Reference level used for measurements (technical but normal)

• Tendency – Rising / Falling / Steady

• Crossing (m) – How close the water is to a bridge, road or spillway

• Flood Classification – Below flood level, Minor, Moderate, Major (if defined)

• Plot / Table – Click for the live graph or raw data

How reliable are they?

They’re very reliable most of the time and are one of the best tools we have for flood awareness.

However they measure one location only, not the whole catchment.

Why gauges sometimes fail or go offline

• Solar battery runs down after multiple cloudy / wet days

• Panels get dirty, damaged or shaded

• Mobile or radio communications drop out

• Floodwater damages cables, boxes or mounts

• Sensors get fouled by debris, silt or movement

• Lightning and moisture damage electronics

When this happens, the river can still be rising — the data just isn’t getting through.

Important: Grey does NOT mean broken

Grey icons or “No classification” simply mean that site does not have official flood thresholds assigned.

It can still be reporting data normally.

How to tell if a gauge is actually working

• Check the timestamp

If it’s updating within the last 10–30 minutes → working

• If it’s hours old or missing → likely offline or degraded

• Look for flat-line data during rain

• If radar shows heavy rain but the river level hasn’t moved for hours → suspect an issue

• Compare with nearby stations

If neighbouring gauges respond but one doesn’t → likely a local fault

• There is no public “offline sensor list” — timestamps are the only real indicator.

Who owns the gauges and the data • Many gauges are owned and maintained by local councils and water authorities

• Some are maintained directly by BoM or state agencies

• Data is shared into the BoM system for public display

If a locally owned gauge fails, BoM will also show missing data because the feed has stopped.

Best way to use river alerts Use them alongside:

• Radar and rainfall

• Local observations

• Road closures and council updates

If a gauge goes missing — treat it as unknown, not safe.