Sirens sounded at 05:12 on Friday across 11 communities along the Danube in Upper Austria, sending 2,140 residents to higher ground after a newly merged regional warning system mistook a 2013 river crest for a live flood. The river was low; no homes were damaged and no one was injured.
The alert prompted people in Grein, Mauthausen and nine nearby communities to leave riverside streets for schools and sports halls on higher ground. Pauliina Vanhoja, the Grein district coordinator, said staff opened the assembly points within minutes. “People came calmly, helped neighbours and followed the routes we had practised,” she said.
A false reading goes live
The error came during the first shift of the new Danube Basin Warning Office, created when two regional flood-monitoring rooms were combined under a €38 million (about $44 million) government programme. The office’s AI-assisted software had been set up to match gauge records from the old systems. It linked an archived 6.72-metre crest reading to a live sensor near Grein.
At the new control room, the reading crossed the evacuation threshold and an operator approved the warning. Sirens and mobile alerts followed. Bartek P. Zając, the office’s operations director, said staff spotted the mismatch within eight minutes and cancelled the alert, but not before 18,600 phones had received it.
The sirens were wrong, but the people were ready before we could finish the second call.
Pauliina Vanhoja, Grein district coordinator
No one was hurt, and officials credited regular local drills with keeping roads clear and assembly points orderly. “The system failed its first public test; the people passed theirs,” Zając said. He confirmed the AI tool did not send the alert on its own: a staff member accepted its suggested sensor match before the system issued the warning.
Merger faces a hard test
The merger was approved in June to replace separate monitoring rooms with one service covering the Danube corridor. The government said consolidation would improve overnight staffing and bring older gauges onto a common platform. Friday’s failure has put the rollout under scrutiny just as the new office was due to take responsibility for all regional alerts.
Vanessa Vuković, a member of the Upper Austria assembly’s public-administration committee, said the service should not restart automated alerts until the gauge links had been checked by people and tested against archived data. The provincial government has paused the system’s automatic warning function and ordered a technical review, with findings due by 9 October.
In Grein, residents began returning home after officials confirmed the river posed no immediate threat. Maggie Demers, who runs a bakery near the old town, said she went to the assembly hall with her sister and neighbours. “It was frightening to wake to the siren, but seeing so many people help each other made the morning feel less like a failure,” she said.
The warning office will keep its experienced operators on manual duty while the review proceeds. Officials say the merged service can still meet its central aim—one staffed control room throughout the night—but only after every sensor match is checked and a fresh public test is completed.
