The lifelong Grantham resident knew plenty about floods.
Family knowledge passed down to her dictated where she should look for the water rising, and when it reached a spot near the dairy shed, head to the high ground of the railway line.
But still she came terribly close to being one of the 17 confirmed victims of the January 10 flood that tore through the Lockyer Valley, west of Brisbane.
Mrs Mahon and her husband were engulfed by churning brown water in their own home.
With two of their daughters and two grandsons they said the Lord's Prayer and goodbye to each other, but were able to scramble on to the roof and were rescued by helicopter.
Mrs Mahon deserves answers as to why the only warning she had was phone calls from two family members that day, and her gut feeling in the weeks before.
The Queensland Floods Commission of Inquiry is considering early warning systems.
It has already heard from consultant hydrologist Dr Phillip Jordan who said that although the Bureau of Meteorology (BoM) didn't have gauges where the intense rain fell, it could have used others to confirm the disaster the radar was hinting.
The BoM had a severe weather warning out on January 10 but it could have given the Lockyer Valley a better heads up about the deadly force building in the creeks, he said.
Following Victoria's 2009 Black Saturday bushfires, Telstra was selected to provide an emergency alert service.
It was used 39 times between November 27, 2010, and January 30, 2011, for warnings related to flooding in Queensland.
It can send up to 500 text messages per second and 1000 voice messages per minute to people based on their billing address.
An example from the Darling Downs town of Dalby on January 9 reads: "Dalby Council anticipates Myall Ck to rise to 3m by 6am 10 Jan. Water in Russel St. Concerned people should evac to family/friends or Dalby Ag Collge (sic)" followed by a phone number.
It's quick and convenient but not without flaws.
If your mobile is switched off, obviously you don't get the text message.
You also don't get it if you don't have reception, a massive problem in rural Queensland.
In the Lockyer Valley, residents reported getting the text message hours after the event.
One suggestion to the inquiry was a system from a company that monitors the weather around the clock and has the power to warn the public as soon as it sees danger coming.
The company, Early Warning Network, is used by Brisbane City Council and others, and proposes expanding to a national service.
Brisbane ratepayers can opt to have the network text, call and email them, if, for example, they live in an area prone to tidal flooding, and want warning of a king tide.
The company's Kerry Plowright says that way, authorities are less likely to be "caught with their pants down".
"The lesson learned here is that a facility needs to be in place that is situationally aware, does not have to 'gear up' and can act immediately under its own authority," he writes.
There's agreement among many of those appearing before the inquiry that any new warning system should use various methods - TV, all radio stations, mobile and fixed phones.
Councils have been at pains to demonstrate they did their best to inform people through traditional media like radio as well as online social media.
But the idea that putting information on websites was adequate inflamed the public gallery at a hearing in Dalby, where someone snapped: "We don't live on bloody computers".
State MP for Lockyer, Ian Rickuss, told reporters that cars should drive around blasting sirens if they must.
He sent out 4000 questionnaires to his flooded constituents so they could more easily give feedback to the commission.
They were asked whether an early warning<
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