At first we all thought they were rust, or brick dust, because of the bright color, but we could see on closer examination that they had legs and were moving, and actively. Their bodies were elongated and perhaps 1/8" or a little longer, with waving appendages.
They remained for about 5 days or so at the bottom of that pool and then dwindled rapidly over the course of a couple of days, finally to disappear.
What are they???
If they hadn't been somewhat sausage-like, I might have thought they were water mites, and if they had been a little more elongated I might think them to be midge larvae, which can both be orange, small, and present in the spring water runoff. But now, we do not know.
They are pretty cool, though, and I'm sorry I did not scoop some up into a jar and take a look under a microscope. I did mean to. Ah, well ...
Yours in curiosity,
Ted and Emma
Photo Credit: Grace Mougalian