The 86-year-old had been alone in her home south of Haast, when the river burst, and was quickly evacuated by her family, who rushed to her aid from nearby Hannahs Clearing.
The family had quickly moved all the vehicles on the property up on to Jackson Bay Rd to stop them from washing away.
Mrs Horne said the flooding was a scene that she had never seen.
''The current was so strong.
''I've lived here 40 years but I've never seen something like that.''
Mrs Horne spent much of yesterday with daughter-in-law Lynda Horne, clearing out her garden shed and laundry, both full of silt, while her front garden resembled a swamp.
Lynda Horne, who lived in the house as a child, said she had never seen a flood of that size.
''We've had floods before, but nothing like that.
''It just caused havoc.
''It was really, really scary because the current was so strong.
''It just kept coming up and up.
''It was just a river coming through here.''
She felt for the owners of neighbouring whitebait cribs, one of which was drenched with water and silt after the river flowed through it at the same height as the window sill.
''I think nearly every home in this area of Waiatoto has had water through it.
''There's going to have to be a huge clean-up, and that's just here.''
The crib owners were on their way to assess the damage, some from as far as Auckland.
Lynda Horne said the damage was not restricted to the Waiatoto, and she knew of two families near the Okuru River whose homes had received flood damage.
''They both got about eight inches of water, which is something they've never had before.''
Despite the mess, which she described as looking like a ''bomb site'', she remained positive.
''You've got to dust yourself off. Life goes on.
''Now, it's just heads down, get into it and get it cleaned up the best we can.''
