I've dealt first hand with how intense run-off flows can be. It was due to a huge oversight in a grading plan of a 36hole Jack Nickaluas designed gold course/resort development; one that included no sandbags around miles of perimeter, and, the removal of an entire hill that separated our community from a drainage area, 250+acres, that would have never been able to get to us. That drainage, ran north to south naturally (but was changed to flow east towards us). But, they removed a hill, and turned that whole other canyon drainage onto us at 100% without a single sandbag in place. I've got pictures of what appeared to be a large western river flowing east into our community, and dumping mud, and clogging hillside drainage systems. And not a single sand bag to be seen.
I'd go so far as to suggest collusion between the county grading supervisor (who was set to retire in minimal time; a month?), and the golf course developer.
Why would a soon to retire golf enthusiast, grading inspector, have interest in backing a 36hole Jack Nicklaus desgined gold course?
Nope, he insisted that they'd done nothing wroing, despite not having a single sandbag in place months after that hard set deadline (literally miles of sandbags two courses high would have been required, just around the perimeter).
This was storm one of the '97/'98 EL Nino cycle (massive!), and, we had giant storms stacked up to Japan. I personally bought several thousand dollars worth of sandbags, and built a military grade bunker encampment at the edge of a giant cribwall, whose drain had been destroyed; and I built an 85' long drain channel down a 2:1 cut slope that I lived at the edge of, and was endanger of coming off of. A long, long, story of months of intensity followed. I was out in every drop, checking miles of drainage and cleaning out filters that I built.
Everyone, at least the experts, told me my efforts would fail, including our own civil engineer, the grading development, and the county engineer. They insisted theirs was right, and mine would fail.
Me: Real background working at a ski resort, and, being part of the crew that was tasked with keeping slope runoff out of a creek with endangered cutthroat trout.
There "injuneered" effort failed with the first heavy mist.
Mine, with my sandbags and chicken wire and stakes, and a 100' piece of 6" pipe, got us through nearly 40" of rain, without a hiccup.
I'm hesitant to ask, but, obviously, you're near some form of flow area?
Or, was that just one of those cruel twists of fate, delivered?
Beautiful place! wow.
I feel for your mom. I built a goldfish pond that I maintained for at least 15 years, before the fish started passing of old age, and the waterfall filter return flow needed fixing (we sold the house, and I disassembled the pond)..
Those things are pets, and that sucks.